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HomeMy WebLinkAboutCOM2010-00077 Stormwater Site Plan - COM Engineering / Geo-Tech Reports - 8/30/2010 JWM&A Jerome W.Morrissette&Associates Inc.,P.S. 1700 Cooper Point Road SW,#13-2,Olympia,WA 98502-1110 (360)352-9456 FAX(360)352-9990 March 29, 2013 Attn. Rebecca Hersha, Planner Mason County DCD P.O. Box 186 Shelton, WA 98584 RE: Blue Heron Condominium Stormwater Final Inspection Report Dear Rebecca: In accordance with the project permit conditions (COM2010-00077), we performed site inspections of the properly during and subsequent to construction. We hereby verify that the storm water improvements and temporary erosion and sediment control measures were installed in general compliance with the approved Storm Water Plan dated August 2010, and that the final work has been completed according to the approved design. Please feel free to contact us with any questions. Very truly yours, JEROME W. MORRISSETTE &ASSOCIATES INC., P.S. 04 60Lui Dan Osier, P.E. Project Engineer Z:\2010 Projects\10117 Blue Heron\040413 blue heron final inspection.docx Civil • Municipal - Geolechnical • Land Surveying 1of1 1 BLUE HERON RESORT & CONDOMINIUM COMMUNITY BUILDING RECONSTRUCTION Stormwater Site Plan Construction Stormwater Pollution Prevention Plan Owner: Blue Heron Condominium 6520 East State Highway 106 Union, WA 98592 Proponent: Mr. Robert J. Macht, CMCA, AMS Property Management Division Bradley Scott Comm. Real Estate 400 Warren Avenue, Ste 450 Bremerton, WA 98337 Prepared By: Daniel J. Osier, P.E. Jerome W. Morrissette & Associates Inc., P.S. 1700 Cooper Point Road SW, #132 Olympia, WA 98502 (360) 352-9456 Submitted: August, 2010 BLUE HERON RESORT & CONDOMINIUM COMMUNITY BUILDING RECONSTRUCTION Stormwater Site Plan Construction Stormwater Pollution Prevention Plan Owner: Blue Heron Condominium 6520 East State Highway 106 Union, WA 98592 Proponent: Mr. Robert J. Macht, CMCA, AMS Property Management Division Bradley Scott Comm. Real Estate 400 Warren Avenue, Ste 450 Bremerton, WA 98337 Prepared By: Daniel J. Osier, P.E. Jerome W. Morrissette & Associates Inc., P.S. 1700 Cooper Point Road SW, #132 Olympia, WA 98502 (360) 352-9456 Ji 53 Submitted: August, 2010 Revised September, 2010 0 39390 ss oNAL q-2�f TABLE OF CONTENTS I. STORMWATER SITE PLAN Section 1 — Project Overview 3 Section 2 — Existing Conditions Summary 3 Section 3 — Offsite Analysis Report 4 Section 4 — Permanent Stormwater Control Plan 4 Section 5 — Construction Stormwater Pollution Prevention Plan 5 Il. APPENDICES 1. Soil Resource Report 2. Geotechnical Report 3. Vicinity Map 4. Conveyance System Analysis / WWHM3 Output 5. Storm Basin Plan 6. Stormwater & Erosion Control Plans Ill. CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN (See separate table of contents included in this section) Blue Heron Resort & Condominium 2 Stormwater Site Plan JWM&A#10117 PART I. STORMWATER SITE PLAN This report has been prepared in accordance with the 2005 Stormwater Management Manual for Western Washington. Section 1 —Project Overview: The owners of the Blue Heron Resort and Condominium propose to reconstruct the Community Building that was destroyed by fire in September 2009. The proposed building is approximately the same size as the previous structure, with a footprint of 2,850 SF. Included is the construction of replacement concrete walkways and patio area adjacent to the existing pool deck. The proposed project is located at 6520 East State Highway 106, Union, Washington, in Mason County, Washington. The subject property includes the following assessor's tax parcel numbers: 1) 322325010401 2) 322335242006 3) 322335289004 Section 2 - Existing Conditions Summary: The subject site is located approximately 0.4 miles north of the intersection of E Dalby Road. The 7.4 acre property was developed in the 1970's and includes three condominium buildings with 22 total units, a combined office/shop, manager's residence, and several outbuildings. The property is bordered by undeveloped forested property to the west, by single family residences to the north and south, and Highway 106 to the east with Hood Canal approximately 150 feet beyond. Site topography slopes toward the east at an average slope of 5%. A 130-foot long by 12-foot wide grass bio-infiltration swale is located immediately east of the tennis courts on the westernmost portion of the property. There are no sensitive or critical areas on site. The USDA Natural Resources Conservation Service Soil Survey of Mason County designates the onsite soils as Cloquallum silty clay loam, 5 to 15% slopes. The Cloquallum series is described as silty lacustrine deposits, with deep and moderately well drained soils. According the report prepared by Bradley- Noble Geotechnical Services, the soils encountered onsite are not consistent with the Soil Survey description, and exhibit the characteristics silty fine sands with low permeability. For further information, refer to the Appendices for the Soil Resource Report and geotechnical report. Stormwater runoff from the site is conveyed through a network of pipes that crosses under Highway 106 and discharges into Hood Canal in two places. Blue Heron Resort& Condominium Stormwater Site Plan JWM&A#10117 Section 3 — Off-site Analysis Report: This project does not meet the threshold requirements given in Volume 1 of the SWMM, Section 3.1.3 for a detailed offsite analysis. Field investigation of the adjacent areas indicates that stormwater runoff from the upslope property to the west is intercepted by the roadside swale of East Orre Nobles Road. From there it is conveyed across the southern portion of the Blue Heron Condominium parcel in a series of ditches and 12"-diameter pipes to the east. Runoff from the southern portion of the subject parcel, including the new Recreation Center roof drains, ultimately joins this offsite flow at the southeasterly corner of the property, travels to the south along a roadside ditch on the west side of Highway 106, then, at the intersection of E Mason Avenue, is conveyed beneath Highway 106 to Hood Canal in a 12"-diameter concrete pipe. The existing outfall, which has likely been functioning for at least 40 years is in fair condition only, but includes adequate energy dissipation. The negligible increase in discharge will not result in an adverse impact to the receiving waters. Refer to the Basin Plan and Conveyance System Analysis in the Appendices for further information. Section 4— Permanent Stormwater Control Plan: The project adds 3,052 SF of pollution-generating impervious surface to the site. Per SWMM Minimum Requirement #6, the threshold for stormwater treatment facilities is 5,000 SF, thus runoff treatment is not required. This new impervious surface is comprised primarily of a new fire access road which will experience minimal vehicular traffic. The project also replaces 4,265 SF of non-pollution-generating impervious surface (2,850 SF roof and 1,415 SF sidewalk), as well as 4,100 SF of pollution- generating pervious surface (landscaping) per the definitions in the SWMM. Per Volume 1 of the SWMM, Section 2.4.2, the project shall comply with Minimum Requirements #1 through #5. F AREA TABULATION REPLACED REPLACED PROPOSED REPLACED NON-PGIS NON-PGIS PGIS DRIVEWAY PGPS TOTAL AREA ROOF SIDEWALK FIRE ACCESS LANDSCAPING 2,850 SF 1,415 SF 3,052 SF 4,100 SF 11,417 SF 0.065 AC 0.032 AC 0.070 AC 0.094 AC 0.262 AC The proposed building will be roofed with a vinyl (PVC) waterproofing membrane, which is considered a non-pollution-generating surface. This project falls below the threshold requirements for treatment and flow-control facilities. This project discharges to Hood Canal via existing drainage systems (per Minimum Requirement #4) and is exempt from flow-control requirements. Refer to the Appendices for the Conveyance System Analysis and Stormwater Plans Blue Heron Resort& Condominium 4 Stormwater Site Plan JWM&A#10117 The SWMM encourages BMP's that infiltrate stormwater runoff onsite. However, as noted in the geotechnical report (Appendix 2), onsite "soils are of low permeability and porosity which cause the saturation to the surface observed." Thus, stormwater infiltration is not a practical option due to the silty soils, high groundwater table, and moderate slopes at the site. The completed project creates minimal potential for pollutant sources. As noted above, the threshold for stormwater treatment is not exceeded. The project Owner will implement the applicable BMP's for landscaping and lawn/vegetation management as described in Volume IV of the SWMM. Other operational and structural source control BMP's in the manual do not apply to this project. Section 5 — Construction Stormwater Pollution Prevention Plan: The Construction SWPPP is included as a standalone section of this report. Blue Heron Resort & Condominium Stormwater Site Plan JWM&A#10117 APPENDIX 1 Soil Resource Report Blue Heron Resort& Condominium Stormwater Site Plan JWM&A#10117 _USDA United States A product of the National Custom Soil Resource �— Department of Cooperative Soil Survey, Agriculture a joint effort of the United Report for O NRCS States Department of Agriculture and other Mason County, Federal agencies, State Natural agencies including the Resources Agricultural Experiment Washington Conservation Stations, and local Service participants Blue Heron Condominium ti f V s 0 16 Mason ` iWAW r , j poi l 40 Aw f lw� or ItA `os it ^tom August 4, 2010 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect,or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions.The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning,onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments(http://soils.usda.gov/sqi/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center(http://offices.sc.egov.usda.gov/locator/app? agency=nres) or your NRCS State Soil Scientist(http://soils.usda.gov/contact/ state offices/). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Soil Data Mart Web site or the NRCS Web Soil Survey. The Soil Data Mart is the data storage site for the official soil survey information. The U.S. Department of Agriculture(USDA)prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means 2 for communication of program information (Braille, large print, audiotape, etc.)should contact USDA's TARGET Center at(202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or(202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 SoilMap..................................................................................................................7 SoilMap................................................................................................................8 Legend..................................................................................................................9 MapUnit Legend................................................................................................10 MapUnit Descriptions........................................................................................10 Mason County, Washington............................................................................12 Ac—Alderwood gravelly sandy loam, 15 to 30 percent slopes...................12 Cf—Cloquallum silty clay loam, 5 to 15 percent slopes..............................12 References............................................................................................................14 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area.They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock.They observed and described many soil profiles.A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform,a soil scientist develops a concept,or model,of how they were formed.Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil scientists classified and named the soils in the survey area, they compared the 5 Custom Soil Resource Report individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil- landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and identified each as a specific map unit.Aerial photographs show trees, buildings,fields, roads, and rivers, all of which help in locating boundaries accurately. 6 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 7 Custom Soil Resource Report Soil Map 4 494040 494110 494180 494250 494320 494390 494460 454530 Z 47°21'11" now it lip low Q N a Q 1 47 20 57 493970 494040 494110 494180 494250 494320 494390 494460 4P4530 Map Scale:1:3,230 K pnnted on A size(8.5"x 11")sheet. v N Meters 0 40 80 160 240 Feet 0 150 300 600 900 Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest(AOI) Very Stony Spot Map Scale: 1:3,230 if printed on A size(8.5"x 11")sheet. "-1 Area of Interest(AOI) Wet Spot The soil surveys that comprise yourA01 were mapped at 1:31,680. Soils Other J Soil Map Units Please rely on the bar scale on each ma sheet for accurate ma Special Line Features Y P P Special Point Features Gully measurements. V Blowout Short Steep Slope Source of Map: Natural Resources Conservation Service ® Borrow Pit Web Soil Survey URL: htt //websoilsurve nres.usda. ov i.. Other Y P� Y• 9 X. Clay Spot Coordinate System: UTM Zone 1 ON NAD83 Political Features Closed Depression Cities O This product is generated from the USDA-NRCS certified data as of X Gravel Pit Water Features the version date(s)listed below. Gravelly Spot Ll Oceans Soil Survey Area: Mason County,Washington ® Landfill Streams and Canals Survey Area Data: Version 6,Sep 22,2009 A, Lava Flow Transportation y& Marsh or swamp Rails Date(s)aerial images were photographed: 7/24/2006 5t Mine or Quarry .v Interstate Highways The orthophoto or other base map on which the soil lines were ,,�. US Routes compiled and digitized probably differs from the background ® Miscellaneous water imagery displayed on these maps.As a result,some minor shifting ® Perennial Water Major Roads of map unit boundaries may be evident. Rock Outcrop Local Roads + Saline Spot . . Sandy Spot $ Severely Eroded Spot C Sinkhole Slide or Slip X Sodic Spot Spoil Area Stony Spot Custom Soil Resource Report Map Unit Legend Mason County,Washington(WA645) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI Ac Alderwood gravelly sandy loam, 15 to 30 11.9 25.7% percent slopes Cf Cloquallum silty clay loam,5 to 15 percent 34.4 74.3% slopes Totals for Area of Interest 46.3 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils.On the landscape, however,the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management.These are called contrasting,or dissimilar,components.They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that itwas impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If 10 Custom Soil Resource Report intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps.The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha- Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 11 Custom Soil Resource Report Mason County, Washington Ac—Alderwood gravelly sandy loam, 15 to 30 percent slopes Map Unit Setting Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature:48 to 52 degrees F Frost-free period. 180 to 220 days Map Unit Composition Alderwood and similar soils: 100 percent Description of Alderwood Setting Landform: Drainageways Parent material: Basal till with a component of volcanic ash Properties and qualities Slope: 15 to 30 percent Depth to restrictive feature: 24 to 32 inches to dense material Drainage class: Moderately well drained Capacity of the most limiting layer to transmit water(Ksat):Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table:About 18 to 36 inches Frequency of flooding. None Frequency of ponding: None Available water capacity.Very low(about 2.5 inches) Interpretive groups Land capability(nonirrigated):4e Typical profile 0 to 10 inches: Gravelly sandy loam 10 to 28 inches:Very gravelly sandy loam 28 to 60 inches: Gravelly sandy loam Cf—Cloquallum silty clay loam, 5 to 15 percent slopes Map Unit Setting Mean annual precipitation: 50 to 75 inches Mean annual air temperature: 50 degrees F Map Unit Composition Cloquallum and similar soils: 100 percent Description of Cloquallum Setting Parent material: Silty lacustrine deposits with volcanic ash 12 Custom Soil Resource Report Properties and qualities Slope: 5 to 15 percent Depth to restrictive feature: More than 80 inches Drainage class: Moderately well drained Capacity of the most limiting layer to transmit water(Ksat): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:About 24 to 36 inches Frequency of flooding: None Frequency of ponding: None Available watercapacity. High (about 11.3 inches) Interpretive groups Land capability(nonirrigated): 3e Typical profile 0 to 9 inches: Silty clay loam 9 to 32 inches: Silty clay loam 32 to 60 inches: Silty clay loam 13 References American Association of State Highway and Transportation Officials(AASHTO).2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W.,and L.M.Vasilas,editors.Version 6.0,2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://soils.usda.gov/ Soil Survey Staff. 1999. Soil taxonomy:A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http://soils.usda.gov/ Soil Survey Staff. 2006. Keys to soil taxonomy. 10th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http://soils.usda.gov/ Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://soils.usda.gov/ United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.glti.nres.usda.gov/ United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://soils.usda.gov/ United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://soils.usda.gov/ 14 Custom Soil Resource Report United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. 15 APPENDIX 2 Geotechnical Report Blue Heron Resort& Condominium 6 Stormwater Site Plan JWM&A#10117 Bradley-Noble Geotechnical Services A Division of The Bradley Group, Inc. PO Box 12267, Olympia WA 98508-2267 Phone 360-357-7883 9 FAX 360-867-9307 6 April 2010 Bradley Scott, Inc. Attention: Bob Macht 400 Warren Avenue, Suite 450 Bremerton, Washington 98377-1408 Subject: Geotechnical considerations for the reconstruction of the Community Building at the Blue Heron Resort & Condominium Property located at East 6520 State Highway 106 in Union, Washington. Dear Mr. Macht: met with you, your structural engineer, Mr.James Ashley-Cole, and your Site Manager, Mr. David Brandt on 30 March 2010 to observe site soil conditions exposed after the demolition of the of the former Community Building. The purpose of our site visit was to observe site soil conditions exposed after demolition in the footprint of the former building. From our field discussion, two major geotechnical concerns need to be addressed in the reconstruction. One is providing foundation soil support as the exposed soils are saturated and loose. The other is collection and control of surface and subsurface flows of ground water. We understand that flooding of the former structure had occurred in the past. We understand that the new Community Building will be constructed in the same building footprint of the former structure. At the time of our site visit, we found the upper 1.5 to 2.0 feet of the soils to be very loose and saturated when we probed. Below the loose soils, the probe was stopped by gravels. We also understand from your site manager that the excavator that was used for the demolition became mired in the soft soils when it moved off the slab during its demolition work. We have provided extensive geotechnical work in the Union and Alderbrook areas of Mason County. The site soil profile is not typical of this area. The usual soil profile in undisturbed areas is a thin, poorly developed topsoil over colluvium. The colluvium varies from a few feet to as much as twenty to thirty feet at the toe of slope adjacent to Hood Canal. The colluvium is a mixture of downslope transported material of silty 10040101 Page I of 4 10040101 Page 2 of 4 sands, gravelly sands, and silty sandy gravels. The density of these soils, based on N- values varies from the mid-range of firm to dense. The colluvium is deposited onto either Vashon advance outwash soils of dense to very dense sands and gravels or onto the very dense and highly overconsolidated Skokomish Gravels which crop out in vertical cut faces of the highway west of this property. The loose soils that were exposed in the demolition work as gravelly silty to very silty fine sands and blue-gray silts with gravels. Our interpretation of the history of these soils is that they either represent natural deposition of fine grained soils in shallow depression or they may be fill placed during the development of the project to level the site. We expect that at relatively shallow depth suitable firm bearing soils will be exposed. We also expect that these bearing soils are of low permeability and porosity which cause the saturation to the surface observed. The site soils exposed are unsuitable for use in support of the new Community Building. These soils are loose fine grained and compressible with actual bearing capacity and settlement potential varying point to point across the site. These soils are moisture sensitive and prone to rapid saturation during rain events. To control site development costs, we recommend that site excavation and construction of a structural fill section be delayed to the dry season, typically mid-June through September when weather conditions will allow for the control of moisture contents of the soils. The on-site soils could be reworked and conditioned to moisture contents that would allow for reuse in construction of structural fill sections, but we expect that this cost would exceed the cost of removal and replacement with imported structural fill soils. Site work should consist of the excavation and removal of the existing soils until firm granular soils are exposed. The surface of the exposed firm soils is to be proof-rolled to develop a firm and non-yielding surface. Placement and compaction of a structural fill section that will provide support for footings and slabs on grade is to be constructed in conformance to the enclosed Recommended Grading Specification. The thickness of the structural fill will be controlled by the depth to suitable bearing soils and plan finish grades. To ensure lateral support for foundations, the fill section must extend outside of building lines equal to the depth of the structural fill section. The structural fill section will provide support for standard spread footing with crawl space type of construction or support of standard footings with a concrete slab on grade for the floor system. For preliminary design of the foundation and supported by a structural fill section constructed in conformance with the Recommended Grading Specification, we 10040101 Page 3 of 4 recommend a bearing value of 2000 p.s.f. This value may be increased after review of the material used to constructed the structural fill section and compaction records. A one-third increase in this value will be permissible for short-term wind or seismic loading. Based on our understanding of the geologic section under this area, use of a Site Class C as defined in Table 1613.5.2 of the 2006 International Building Code (IBC) is permissible. Figure 1613.5(2) Maximum Considered Earthquake Ground Motion of 1.0 Second Spectral Response Acceleration (5% of Critical Damping), Site Class B of 0.5G. The site coefficient and adjusted maximum considered earthquake spectral response acceleration parameters are adjusted for the site class effects using Equation 16-37 and 16-38 in the 2006 IBC. Control of surface and ground water flowing to the structural fill pad and building must be addressed in the project's civil engineering. At a minimum, we recommend the construction of a french drain upslope of project perpendicular to the axis of the slope. The location of the french drain will be determined by the project's civil engineer. The depth of the excavation for the french drain will need to be field determined to ensure that it extends to soils of low permeability. A footing drain placed at the base of the foundation is also recommended to be included in the design. We recommend that the footing drain be constructed using rigid plastic pipe. Rigid pipe is more resistant to crushing and deflection than the flexible ADS type of pipe. We also recommend cleanouts be included in the design to allow for future maintenance of the drains if required. Collection of storm water from impervious surfaces must also be addressed in the design. We recommend that all roof rain leaders, yard drains, and catch basins be collected into a tightline collection system. We recommend the use of rigid plastic pipe with glued watertight joints. This storm water collection system must be isolated from the footing drain system. We understand that the project does have a storm water collection system and the storm water collected from this project may be connected to the existing system. Connection of the footing drain into the project system must be at an elevation such that back-up into the footing zone cannot occur. Placement of foundation backfill and site grading to ensure positive flow away from the foundation must conform to the requirements of the IBC Section 1803.2 Placement of Backfill and Section 1803.3 Site Grading. If a crawl space is incorporated in the design, we do recommend that a minimum vertical separation from top of landscape surface to bottom of crawl space of at least three inches. This will prevent the crawl space vents from becoming a conduit for water entry into the crawl space. Good compaction control of the backfill under sidewalks is required to prevent future settlement and deflection. 10040101 Page 4 of 4 If you have any additional geotechnical questions on this report, or if we may be of additional service to you and your design team on this project, please contact us at our Olympia office. Cordially, BRADLEY-NOBLE GEOTECHNICAL SERVICES got W�ah� David C. rong, L.E.G. �� e � o Enclosure: Recommended Grading Specifications ��,17 Bradley-Noble Geotechnical Services A Division of The Bradley Group, Inc. PO Box 12267, Olympia WA 98508-2267 Phone 360-357-7883 • FAX 360-867-9307 RECOMMENDED GRADING SPECIFICATIONS In areas under structures, paving sections, and sidewalks, strip all topsoil and organic material. For structural fill in areas under footings and slab on-grade, we recommend that all soils be compacted to a minimum density of 95% of ASTM D-1557. If the material contains more than 30% by weight retained on the 3/4-inch screen, then the use of the development of a firm and non-yielding surface may be used for compaction control. This includes proof-rolling native soils exposed in the bottom of the excavation prior to placement of fill. Materials under the paving section should also be compacted to the minimum density of 95% of ASTM D 698 by proof-rolling prior to placement of the paving section. This includes proof-rolling in-place soils, soils that have been disturbed during construction, and all structural fill materials. For imported structural fill we recommend that a clean, six-inch minus, well graded gravel or gravelly sand (classifying as GW or SW as determined by ANSI/ASTM test method D-2487) be used. On-site material proposed for use to construct structural fill sections will require the approval by the soils engineer or engineering geologist prior to placement. We also recommend that no more than seven percent by weight pass the #200 screen as tested by ANSI/ASTM D-1 140 test procedure. Other material may be substituted with prior written approval for use by the soils engineer or engineering geologist. Backfll for walls restraining earth should conform to WSDOT 9-03.12 (2) gravel backfill for walls to ensure drainage. All fill should be placed in uniform horizontal lifts of six to eight inches loose thickness, conditioned to the optimum moisture content, and compacted to the specified minimum density before placing the next lift. The lift thickness will be adjusted in the field depending on the gradation of the material, maximum particle size, and compaction equipment being employed by the contractor. It is the owner's testing agency of record who is responsibility to ensure that sufficient density tests or field verification of the fill have been performed to ensure that the required minimum density has been uniformly achieved prior to placement of additional structural fill material. We further recommend that all utility trench backfill be compacted as specified above. Earthwork should be performed by an approved testing laboratory to ensure compliance with the compaction requirements. The testing agency is to be employed by the owner. A final report certifying that specified compaction has been uniformly achieved must be submitted by the testing agency at the completion of site development work. Recommended Grading Specifications Page I of 2 Recommended Grading Specifications Page 2 of 2 Placement of fill sections on slopes greater than 5:1 (horizontal to vertical) will be benched as directed into native soils. Height and width of the bench will be determined in the field by the soils engineer or engineering geologist Unrestricted slopes shall not exceed 2:1 (horizontal to vertical) for fill embankments and cuts that expose native soils without written approval by Bradley-Noble Geotechnical Services. All fill slopes will be rolled. The project's civil engineer is responsible for the protection of the constructed fill slopes from uncollected runoff. All fill slopes will be compacted by track rolling or other approved methods to densify the surface of the fill slope. We recommend that all cut-and-fill slopes be seeded as soon as possible after construction to allow the establishment of vegetation to protect the slope from sheet washing. Placement of fill will be suspended during periods of unfavorable weather. No fill is to be placed while the fill is frozen or thawing . When work is stopped by rain, the placement of fill will not resume until the soils engineer or engineering geologist determines that the moisture content is suitable for compactive effort and that the previously placed fill had not been loosened. The contractor will take appropriate measures during unfavorable weather to protect the fill already in place. Measures that may be required include the limiting of wheeled traffic and grading to provide temporary drainage of the fill. At the direction of the soils engineer or engineering geologist, the contactor will be responsible for the removal or reworking of fill that has softened to less than the required compaction. APPENDIX 3 Vicinity Map Blue Heron Resort& Condominium Stormwater Site Plan JWM&A#10117 HOOD CANAL NF LATCH NOp� S Rp, HOOD CANAL PROJEC 06 LOCATION uI E. D Y RD SR o� m A E. MANZANITA DR. SKOKOMISH L E INDIAN RESERVATIO 2- tea. VICINITY MAP N.T.S. APPENDIX 4 Conveyance System Analysis / WWHM3 Output Blue Heron Resort & Condominium 8 Stormwater Site Plan JWM&A#10117 Blue Heron Resort Version 1.0:5th August 2010:12:00 P.M. Conveyance Calculations: Manning's Equation:V=(k/n)(A/P)213(S)0.5 Theoretical Wetted Corresponding Tributary Velocity 2-Year Flow 10-Year 25-Year Full Flow Full Flow Ratio k=1.49: For Unit Manning Perimeter Reach ID Basins Area (ac) (ft/s) (cfs) Flow (cfs) Flow (cfs) (cfs) (25-yr) Size(ft) Conversion Coefficient(n) Area (ft') (ft) Slope (ft/ft) Ex. Culvert-1 61 1.280 5.644 0.139 0.269 0.373 4.431 0.08 1.000 1.49 0.022 0.785 3.140 0.0441 Ex.Culvert-2 Al 1.100 13.018 0.139 0.269 0.373 10.219 0.04 1.000 1.49 0.012 0.785 3.140 0.0698 Pro. CB-1 A2 0.049 3.725 0.018 0.029 0.036 0.731 0.05 0.500 1.49 0.010 0.196 1.570 0.0100 Pro. CB-2 A2 0.105 3.725 0.056 0.092 0.113 0.731 0.15 0.500 1.49 0.010 0.196 1.570 0.0100 Ex.CB-1 Al 1.323 3.762 0.313 0.546 0.693 1.314 0.53 0.667 1.49 0.012 0.349 2.094 0.0100 Pro.CB-3 A2 0.188 4.514 0.444 0.757 0.951 1.576 0.60 0.667 1.49 0.010 0.349 2.094 0.0100 Pro. CB-4 A2 0.249 3.725 0.121 0.178 0.211 0.731 0.29 0.500 1.49 0.010 0.196 1.570 0.0100 Pro.CB-5 A2 N.A. 5.528 1 0.565 0.935 1.162 1 1.931 0.60 0.667 1.49 0.010 0.349 2.094 0.0150 Pro. CB-6 A2 N.A. 5.851 0.686 1.113 1.373 2.043 0.67 0.667 1.49 0.010 0.349 2.094 0.0168 Ex.CB-2 Al &A2 N.A. 10.370 0.653 1.181 1.522 3.622 0.42 0.667 1.49 0.012 0.349 2.094 0.0760 Ex.CB-3 Al,A2, 131, B2&C N.A. 7.634 1.669 2.862 3.544 5.992 0.59 1.000 1.49 0.012 1 0.785 3.140 0.0240 Ex. CB-4 Al, A2, B1, B2&C N.A. 14.741 1.669 2.862 3.544 11.572 0.31 1.000 1.49 0.012 0.785 3.140 0.0895 Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/5/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name Al & A2 Basin: Bypass: No GroundWater: No Pervious Land Use Acres A B, Forest, Mod 1.984 A B, Lawn, Mod .288 Impervious Land Use Acres ROOF TOPS FLAT 0.065 RIDEWALKS FLAT 0.136 'ARKING FLAT 0.438 element Flows To: Surface Interflow Groundwater Name Basin: ypass: No GroundWater: No ervious Land Use Acres A B, Forest, Mod 1.984 A B, Lawn, Mod .288 mpervious Land Use Acres ROOF TOPS FLAT 0.065 SIDEWALKS FLAT 0.136 ARKING FLAT 0.438 lement Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Low Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0. 653136 5 year 0. 94855 10 year 1.181476 25 year 1.522211 50 year 1.812395 100 year 2.136046 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0. 653103 5 year 0. 948482 10 year 1. 181376 25 year 1.522059 50 year 1.812196 100 year 2. 13579 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 2.981 2.981 1958 0.547 0.547 1959 1.119 1.119 1960 0.806 0.806 1961 0.477 0.477 1962 0.945 0.945 1963 0.523 0.523 1964 0.676 0.676 1965 0.473 0.473 1966 0.409 0.409 1967 1.708 1.708 1968 0.775 0.774 1969 0. 699 0.699 1970 0.549 0.549 1971 0.582 0.582 1972 1.039 1.039 1973 0.926 0. 926 1974 0.671 0. 671 1975 0.933 0.933 1976 0.800 0.800 1977 0.998 0.998 1978 0.397 0.397 1979 0.527 0.527 1980 0.437 0.437 1981 0.929 0.929 1982 0.567 0.567 1983 0.564 0.564 1984 0.799 0.799 1985 0.339 0.339 1986 0.500 0.500 1987 0.578 0.578 1988 0.818 0.818 1989 0.495 0.495 1990 0.414 0.414 1991 0.436 0.436 1992 0.874 0.874 1993 0.549 0.549 1994 0.435 0.435 1995 0.852 0.852 1996 0.728 0.728 1997 0.737 0.737 1998 0.519 0.519 1999 0.737 0.737 2000 1.222 1.222 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 2.9808 2.9805 2 1.7082 1.7081 3 1.2222 1.2221 4 1.1189 1.1188 i 5 1.0395 1.0394 6 0.9982 0.9981 7 0. 9451 0. 9451 8 0.9333 0.9333 9 0.9293 0.9292 10 0.9264 0.9263 11 0.8740 0.8739 12 0.8520 0.8520 13 0.8180 0.8179 14 0.8058 0.8058 15 0.8002 0.8001 16 0.7993 0.7992 17 0.7745 0.7745 18 0.7370 0.7369 19 0.7368 0.7367 20 0.7279 0.7279 21 0.6988 0.6987 22 0.6762 0.6761 23 0.6709 0. 6708 24 0.5816 0.5815 25 0.5777 0.5777 26 0.5666 0.5666 27 0.5638 0.5638 28 0.5491 0.5491 29 0.5490 0.5490 30 0.5471 0.5471 31 0.5268 0.5268 32 0.5234 0.5234 33 0.5186 0.5186 34 0.5002 0.5002 35 0.4953 0.4953 36 0.4769 0.4769 37 0.4728 0.4727 38 0.4366 0.4366 39 0.4357 0.4357 40 0.4352 0.4352 41 0.4137 0.4137 42 0.4089 0.4089 43 0.3973 0.3973 44 0.3390 0.3390 POC #1 The Facility PASSED The Facility PASSED. Flow(CFS) Predev Dev Percentage Pass/Fail 0.3266 645 645 100 Pass 0.3416 566 566 100 Pass 0.3566 498 498 100 Pass 0.3716 450 450 100 Pass 0.3866 409 409 100 Pass 0.4016 352 352 100 Pass 0.4166 302 302 100 Pass 0.4316 263 263 100 Pass 0.4466 235 235 100 Pass 0.4616 211 211 100 Pass 0.4767 189 189 100 Pass 0.4917 159 159 100 Pass 0.5067 141 141 100 Pass 0.5217 132 132 100 Pass 0.5367 126 126 100 Pass 0.5517 114 114 100 Pass 0.5667 101 101 100 Pass 0.5817 90 90 100 Pass 0.5967 80 80 100 Pass 0. 6117 75 75 100 Pass 0. 6267 67 67 100 Pass 0. 6417 66 66 100 Pass 0. 6568 60 60 100 Pass 0. 6718 56 56 100 Pass 0. 6868 52 52 100 Pass 0.7018 46 46 100 Pass 0.7168 42 42 100 Pass 0.7318 36 36 100 Pass 0.7468 31 31 100 Pass 0.7618 27 27 100 Pass 0.7768 26 26 100 Pass 0.7918 24 24 100 Pass 0.8068 20 20 100 Pass 0.8218 19 19 100 Pass 0.8369 19 19 100 Pass 0.8519 18 18 100 Pass 0.8669 16 16 100 Pass 0.8819 15 15 100 Pass 0.8969 15 15 100 Pass 0. 9119 15 15 100 Pass 0. 9269 15 15 100 Pass 0. 9419 11 11 100 Pass 0. 9569 9 9 100 Pass 0. 9719 9 9 100 Pass 0. 9869 9 9 100 Pass 1. 0019 7 7 100 Pass 1.0170 7 7 100 Pass 1.0320 7 7 100 Pass 1.0470 6 6 100 Pass 1.0620 6 6 100 Pass 1.0770 6 6 100 Pass 1.0920 5 5 100 Pass 1. 1070 4 4 100 Pass 1.1220 3 3 100 Pass 1.1370 3 3 100 Pass 1.1520 3 3 100 Pass 1.1670 3 3 100 Pass 1.1820 3 3 100 Pass 1.1971 3 3 100 Pass 1.2121 3 3 100 Pass 1.2271 2 2 100 Pass 1.2421 2 2 100 Pass 1.2571 2 2 100 Pass 1.2721 2 2 100 Pass 1.2871 2 2 100 Pass 1.3021 2 2 100 Pass 1.3171 2 2 100 Pass 1.3321 2 2 100 Pass 1.3471 2 2 100 Pass 1.3621 2 2 100 Pass 1.3772 2 2 100 Pass 1.3922 2 2 100 Pass 1.4072 2 2 100 Pass 1.4222 2 2 100 Pass 1.4372 2 2 100 Pass 1.4522 2 2 100 Pass L.4672 2 2 100 Pass L. 4822 2 2 100 Pass 1.4972 2 2 100 Pass 1.5122 2 2 100 Pass _.5272 2 2 100 Pass _.5422 2 2 100 Pass 1.5573 2 2 100 Pass 1.5723 2 2 100 Pass _.5873 2 2 100 Pass _.6023 2 2 100 Pass 1. 6173 2 2 100 Pass '.. 6323 2 2 100 Pass .. 6473 2 2 100 Pass ..6623 2 2 100 Pass 1. 6773 2 2 100 Pass '..6923 2 2 100 Pass ..7073 2 2 100 Pass _.7223 1 1 100 Pass 1 1'2'7n 1 1 1 .,.. ... 1.7524 1 1 100 Pass 1.7674 1 1 100 Pass 1.7824 1 1 100 Pass 1.7974 1 1 100 Pass 1.8124 1 1 100 Pass Water Quality BMP Flow and Volume for POC 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/5/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name B1 Basin: Bypass: No Groundwater: No Pervious Land Use Acres A B, Forest, Mod 1.28 Impervious Land Use Acres Element Flows To: Surface Interflow Groundwater Name B1 Basin: Bypass: No GroundWater: No Pervious Land Use Acres A B, Forest, Mod 1.28 Impervious Land Use Acres Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.138843 5 year 0.268941 10 year 0.327666 25 year 0.372755 50 year 0.392006 100 year 0.403759 Flow Frequency Return Periods for Mitigated. POC #1 L96T'O L96T'0 ZT OL6T'0 OL6T'O TT 9STZ'0 99TZ'O OT 86£Z'0 86£Z'0 6 ZSPZ'0 ZSbZ'0 8 ZS9Z'0 ZS9Z'0 L TSLZ'0 TSLZ'0 9 OS6Z'O O96Z'0 S ZbT£'0 ZbT£'0 6 bbT£'0 PVT£'0 £ T£SS'0 T£SS'0 Z bb80'T b�80'T T pa.4-ebz-4TN padoTanapaad xuEg T# 00d 'pagsbigTN put padoTaeapaad a09 sxzad ATasaA paxuag PT£'0 6T£'0 OOOZ 69T'0 69T'0 666T Z90'0 Z90'0 866T ££T '0 ££T'O L66T 6LT'0 bLT'0 966T SLT '0 SLT'O S66T 6b0'0 6b0'0 P661 £80 0 £80'0 £66T L6T '0 L6T'0 Z66T OTO'O OTO'0 T66T SSO'0 99O'0 066T SSO'0 SSO'0 686T L61'0 L6T'0 886T 960'0 960'0 L86T T00 '0 T00'0 986T 800'0 800'0 S86T 69T '0 69T'0 P86T ££0'0 ££0'0 £86T 60T'0 60T'O Z86T OPZ'0 ObZ'0 T86T £SO'0 £SO'0 086T ZSO'0 ZSO'0 6L6T Zb0'O Zb0'0 8L6T S6Z'0 96Z'0 LL6T 8ST '0 8ST'0 9L6T 9TZ'0 9TZ'0 SL6T 6bT'0 6PT'0 PL6T SPZ'0 SbZ'0 £L6T SLZ'O SLZ'0 ZL6T 860'0 860'0 TL6T OLO'O OLO'O OL6T £ST'0 £ST'0 696T 08T '0 08T'0 896T £SS'0 £SS'0 L96T £9O'0 £SO'0 996T LLO'0 LLO'0 996T S£T 'O S£T'0 b96T 8£0'0 8£0'0 £96T S9Z'0 99Z'0 Z96T 890'0 890'0 T96T LLT'0 LLT'0 096T PT£'0 6T£'0 696T 060'0 060'0 8S6T b80'T b80'T LS6T pale 74TW pa oTanapaad asaA T# 00d put padoTanapaad aoff sxsad ATav9X 6SL£Ob'0 a-eel, OOT 900Z6£'0 aleaA OS SSLZL£'0 aegA SZ 999LZ£'0 aegA OT Tb689Z'0 a-eaA S £b88£T'0 a-eaA z (S3o)MoT3 poiaed uan-4ag ssed OOT T£ T£ ZL9T'0 ssed OOT ££ ££ 6£9T'C seed OOT S£ S£ L09T'C ssed OOT 9£ 9£ VLST'0 Ss2d OOT 8£ 8£ TVST'O ss2d OOT £V £V 60ST'C ss2d OOT VV VV 9LVT'C seed OOT Lb Lb VVVT'0 ss2d OOT 6V 6V TTVT'O ss2d OOT SS SS 8L£T'C ss2d OOT 09 09 9V£T'C ssed OOT Z9 Z9 £T£T'0 ss2d OOT V9 V9 T8ZT'C ss2d OOT 89 89 8VZT'C Ssed OOT 69 69 9TZT'C Ssed OOT ZL ZL £8TT'0 ss2d OOT VL VL OSTT'C ssed OOT LL LL 8TTT'C ss2d OOT Z8 Z8 980T'0 ssed OOT 06 06 £SOT'0 ss2d OOT S6 96 OZOT'C Ss2d OOT ZOT NT L860'0 ss2d OOT OTT OTT 9960'0 SSed OOT STT STT ZZ60'0 ss2d OOT 0£T 0£T 0680'C ssed OOT TVT TVT L980'C ss2d OOT LST LST 9Z80'0 ssed OOT 99T 99T Z6L0'0 ssed OOT £8T £8T 6SLO'C ssed OOT Z6T Z6T LZLO'C ssed OOT ZTZ ZTZ V690'0 TT'ea/SSEd aba-4ua0Zrad naa napa=d (S3O)MoT3 'adSSVd A-4TTtoB,g auy aaSSVd 1"4TTTc)Eg atU T# OOd 9000'0 9000'0 VV 6L00'0 6L00'0 £V 6600'0 6600'0 ZV 0££0'0 0££0'0 TV £8£0'0 £8£0'0 OP OZVO'0 OZVO'0 6£ T6V0'0 T6V0'0 8£ LTSO'0 LTSO'0 L£ LZSO'0 LZSO'0 9£ 9£SO'0 9£SO'0 S£ LVSO'0 LVSO'O V£ £SSO'0 £99O'0 ££ ZZ90'0 ZZ90'0 Z£ T890'0 T890'0 T£ ZOLO'O ZOLO'0 0£ L9L0'0 L9L0'0 6Z 8Z80'0 8Z80'0 8Z L680'0 L680'O LZ L960'0 L960'0 9Z 6L60'0 6L60'0 SZ Z60T 'O Z60T 'O VZ 63£T'0 6Z£T'0 £Z VS£T '0 VS£T'0 ZZ 98VT'0 98VT'0 TZ T£ST'0 T£ST'0 OZ V89T'0 V89T'0 6T 989T'0 989T'0 8T Z69T'0 Z69T'0 LT 9VLT'0 SVLT'0 9T SVLT '0 SVLT'0 ST 99LT'0 99LT'0 VT 66LT'0 66LT'0 £T 0.1704 27 27 100 Pass 0.1737 27 27 100 Pass 0.1769 24 24 100 Pass 0.1802 21 21 100 Pass 0.1835 21 21 100 Pass 0.1867 21 21 100 Pass 0. 1900 21 21 100 Pass 0.1932 20 20 100 Pass 0.1965 20 20 100 Pass 0. 1998 17 17 100 Pass 0.2030 17 17 100 Pass 0.2063 16 16 100 Pass 0.2095 15 15 100 Pass 0.2128 15 15 100 Pass 0.2161 14 14 100 Pass 0.2193 14 14 100 Pass 0.2226 14 14 100 Pass 0.2258 14 14 100 Pass 0.2291 14 14 100 Pass 0.2323 13 13 100 Pass 0.2356 12 12 100 Pass 0.2389 12 12 100 Pass 0.2421 11 11 100 Pass 0.2454 11 11 100 Pass 0.2486 10 10 100 Pass 0.2519 10 10 100 Pass 0.2552 10 10 100 Pass 0.2584 8 8 100 Pass 0.2617 8 8 100 Pass 0.2649 8 8 100 Pass 0.2682 7 7 100 Pass 0.2714 7 7 100 Pass 0.2747 7 7 100 Pass 0.2780 6 6 100 Pass 0.2812 5 5 100 Pass 0.2845 5 5 100 Pass 0.2877 5 5 100 Pass 0.2910 5 5 100 Pass 0.2943 5 5 100 Pass 0.2975 4 4 100 Pass 0.3008 4 4 100 Pass 0.3040 4 4 100 Pass 0.3073 4 4 100 Pass 0.3105 4 4 100 Pass 0.3138 4 4 100 Pass 0.3171 2 2 100 Pass 0.3203 2 2 100 Pass 0.3236 2 2 100 Pass 0.3268 2 2 100 Pass 0.3301 2 2 100 Pass 0.3334 2 2 100 Pass 0.3366 2 2 100 Pass 0.3399 2 2 100 Pass 0.3431 2 2 100 Pass 0.3464 2 2 100 Pass 0.3496 2 2 100 Pass 0.3529 2 2 100 Pass 0.3562 2 2 100 Pass 0.3594 2 2 100 Pass 0.3627 2 2 100 Pass 0.3659 2 2 100 Pass 0.3692 2 2 100 Pass 0.3725 2 2 100 Pass 0.3757 2 2 100 Pass 0.3790 2 2 100 Pass 0.3822 2 2 100 Pass 0.3855 2 2 100 Pass 0.3887 2 2 100 Pass 0.3920 2 2 100 Pass Water Quality BMP Floe► and volume for POC 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even. if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. 99L£LL•0 3eaA SZ 89b6b9'0 aeaA OT ££08SS•0 3eeA S L6TT£b•0 aeaA Z (sgo)moT3 pozaed uangag T# OOd 'padoTanapazd aoj spoiaed uangag Aouenbaaa MOTd ssansax srsatVNV asn arrant caivoisiw aageMpunoaO MOTgaaqui aosgans :oy SmOTa 4uameTg 6 L T'0 IvIia Sdom aoold L9Z'0 aoAI sCHOU saaov asn pueZ snoznaa uri 8Sb• PON 'UMLq 'g y saaov asn pueZ snoznaed ON :aageMpunoaO ON :ssedAg Z g aureN aa�eMpunoa� M0T9a94ul eovgans :oy smOTd 4uauraTa 6LT•0 IvIla Sdol aoold L9Z•0 aow SaKOU saaov asn pueZ snotnaa uij 896• Pow 'umvq 'g K saaov asn pueZ snoTAsad ON :aageMpunoaO ON :ssedAg :UTSPS Zg aureN asn arrant asdoasnsaaEd :uoisaan ENHW4 bb•T :aTeoS dioaad O£/60/666T Pua egea TO/OT/996T 4ae4S e4ea auaOTTnO abeO OTOZ/S/8 : agea gaodag uOzup A4TO 90T APMubzg G4e4S 4SPH OZ99 :sseappv 94TS OTnPJGP :aumN 40aEOad sxodaa soamdd T9PON AboToapAg uo'4butt;seM u3:a4saM 50 year 0.872906 100 year 0. 97786 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0. 431197 5 year 0.558033 10 year 0. 649468 25 year 0.773756 50 year 0.872906 100 year 0. 97786 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 1.261 1.261 1958 0.413 0.413 1959 0.615 0. 615 1960 0.485 0.485 1961 0.324 0.324 1962 0.515 0.515 1963 0.438 0.438 1964 0.417 0.417 1965 0.348 0.348 1966 0.285 0.285 1967 0.829 0.829 1968 0.458 0.458 1969 0.419 0.419 1970 0.419 0.419 1971 0.381 0.381 1972 0.563 0.563 1973 0.507 0.507 1974 0.398 0.398 1975 0.550 0.550 1976 0.557 0.557 1977 0.519 0.519 1978 0.281 0.281 1979 0.464 0.464 1980 0.358 0.358 1981 0.509 0.509 1982 0.363 0.363 1983 0.452 0.452 1984 0.578 0.578 1985 0.276 0.276 1986 0.406 0.406 1987 0.379 0.379 1988 0.475 0.475 1989 0.355 0.355 1990 0.283 0.283 1991 0.344 0.344 1992 0.514 0.514 1993 0.372 0.372 1994 0.339 0.339 1995 0.538 0.538 1996 0.421 0.421 1997 0.476 0.476 1998 0.434 0.434 1999 0.427 0.427 2000 0. 675 0. 675 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 1.2610 1.2610 2 0.8294 0.8294 3 0. 6752 0.6752 4 0. 6146 0.6146 5 0.5780 0.5780 6 0.5632 0.5632 7 0.5566 0.5566 8 0.5503 0.5503 9 0.5384 0.5384 10 0.5190 0.5190 11 0.5150 0.5150 12 0.5140 0.5140 13 0.5094 0.5094 14 0.5067 0.5067 15 0.4848 0.4848 16 0.4763 0.4763 17 0.4754 0.4754 18 0.4637 0.4637 19 0.4583 0.4583 20 0.4524 0.4524 21 0.4384 0.4384 22 0.4342 0.4342 23 0.4265 0.4265 24 0.4214 0.4214 25 0.4193 0.4193 26 0.4186 0.4186 27 0.4166 0.4166 28 0.4128 0.4128 29 0.4057 0.4057 30 0.3980 0.3980 31 0.3807 0.3807 32 0.3795 0.3795 33 0.3718 0.3718 34 0.3635 0.3635 35 0.3581 0.3581 36 0.3547 0.3547 37 0.3477 0.3477 38 0.3439 0.3439 39 0.3390 0.3390 40 0.3242 0.3242 41 0.2847 0.2847 42 0.2831 0.2831 43 0.2810 0.2810 44 0.2755 0.2755 POC #1 The Facility PASSED The Facility PASSED. Flow(CFS) Predev Dev Percentage Pass/Fail 0.2156 807 807 100 Pass 0.2222 747 747 100 Pass 0.2289 701 701 100 Pass 0.2355 648 648 100 Pass 0.2422 602 602 100 Pass 0.2488 560 560 100 Pass 0.2554 513 513 100 Pass 0.2621 469 469 100 Pass 0.2687 429 429 100 Pass 0.2754 381 381 100 Pass 0.2820 342 342 100 Pass 0.2886 298 298 100 Pass 0.2953 271 271 100 Pass 0.3019 261 261 100 Pass 0.3086 229 229 100 Pass 0.3152 199 199 100 Pass 0.3218 181 181 100 Pass 0.3285 167 167 100 Pass 0.3351 158 158 100 Pass 0.3417 151 151 100 Pass 0.3484 141 141 100 Pass 0.3550 130 130 100 Pass 0.3617 123 123 100 Pass 0.3683 112 112 100 Pass 0.3749 100 100 100 Pass 0.3816 94 94 100 Pass 0.3882 90 90 100 Pass 0.3949 83 83 100 Pass 0.4015 73 73 100 Pass 0.4081 68 68 100 Pass 0.4148 65 65 100 Pass 0.4214 58 58 100 Pass 0.4281 53 53 100 Pass 0.4347 47 47 100 Pass 0.4413 40 40 100 Pass 0.4480 38 38 100 Pass 0.4546 33 33 100 Pass 0.4613 32 32 100 Pass 0.4679 31 31 100 Pass 0.4745 30 30 100 Pass 0.4812 28 28 100 Pass 0.4878 25 25 100 Pass 0.4945 25 25 100 Pass 0.5011 23 23 100 Pass 0.5077 21 21 100 Pass 0.5144 20 20 100 Pass 0.5210 16 16 100 Pass 0.5277 14 14 100 Pass 0.5343 13 13 100 Pass 0.5409 10 10 100 Pass 0.5476 10 10 100 Pass 0.5542 9 9 100 Pass 0.5609 8 8 100 Pass 0.5675 7 7 100 Pass 0.5741 7 7 100 Pass 0.5808 6 6 100 Pass 0.5874 6 6 100 Pass 0.5940 6 6 100 Pass 0.6007 6 6 100 Pass 0. 6073 6 6 100 Pass 0. 6140 6 6 100 Pass 0.6206 5 5 100 Pass 0.6272 4 4 100 Pass 0. 6339 4 4 100 Pass 0. 6405 4 4 100 Pass 0. 6472 4 4 100 Pass 0. 6538 4 4 100 Pass 0. 6604 4 4 100 Pass 0. 6671 4 4 100 Pass 0. 6737 4 4 100 Pass 0. 6804 2 2 100 Pass 0. 6870 2 2 100 Pass 0. 6936 2 2 100 Pass 0.7003 2 2 100 Pass 0.7069 2 2 100 Pass 0.7136 2 2 100 Pass 0.7202 2 2 100 Pass 0.7268 2 2 100 Pass 0.7335 2 2 100 Pass 0.7401 2 2 100 Pass 0.7468 2 2 100 Pass 0.7534 2 2 100 Pass 0.7600 2 2 100 Pass 0.7667 2 2 100 Pass 0.7733 2 2 100 Pass 0.7800 2 2 100 Pass 0.7866 2 2 100 Pass 0.7932 2 2 100 Pass 0.7999 2 2 100 Pass 0.8065 2 2 100 Pass 0.8132 2 2 100 Pass 0.8198 2 2 100 Pass 0.8264 2 2 100 Pass 0.8331 1 1 100 Pass 0.8397 1 1 100 Pass 0.8463 1 1 100 Pass 0.8530 1 1 100 Pass 0.8596 1 1 100 Pass n atiti� 1 1 1nn ^--- 0.8729 1 1 100 Pass Water Quality BMP Flow and Volume for POC 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/5/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name C Basin: Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .734 Impervious Land Use Acres ROADS MOD 0.317 Element Flows To: Surface Interflow Groundwater Name C Basin: Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .734 Impervious Land Use Acres ROADS MOD 0.317 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0. 44574 5 year 0.594402 10 year 0.704106 25 year 0.856096 50 year 0.979427 100 year 1.111763 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.44574 5 year 0.594402 10 year 0.704106 25 year 0.856096 50 year 0.979427 100 year 1.111763 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 1.405 1.405 1958 0.371 0.371 1959 0.678 0. 678 1960 0.523 0.523 1961 0.331 0.331 1962 0.564 0.564 1963 0.449 0.449 1964 0.438 0.438 1965 0.342 0.342 1966 0.289 0.289 1967 0.923 0.923 1968 0.497 0.497 1969 0.451 0.451 1970 0.431 0.431 1971 0.394 0.394 1972 0.615 0. 615 1973 0.551 0.551 1974 0.422 0.422 1975 0.586 0.586 1976 0.584 0.584 1977 0.571 0.571 1978 0.278 0.278 1979 0.466 0.466 1980 0.343 0.343 1981 0.535 0.535 1982 0.385 0.385 1983 0.463 0.463 1984 0.592 0.592 1985 0.270 0.270 1986 0.374 0.374 1987 0.392 0.392 1988 0.513 0.513 1989 0.355 0.355 1990 0.285 0.285 1991 0.323 0.323 1992 0.548 0.548 1993 0.382 0.382 1994 0.338 0.338 1995 0.574 0.574 1996 0.458 0.458 1997 0.499 0.499 1998 0.434 0.434 1999 0.454 0.454 2000 0.737 0.737 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 1. 4052 1.4052 2 0. 9229 0. 9229 3 0.7366 0.7366 4 0.6783 0.6783 5 0. 6146 0. 6146 6 0.5919 0.5919 7 0.5861 0.5861 8 0.5845 0.5845 9 0.5745 0.5745 10 0.5710 0.5710 11 0.5639 0.5639 12 0.5506 0.5506 13 0.5476 0.5476 14 0.5349 0.5349 15 0.5230 0.5230 16 0.5129 0.5129 17 0.4993 0.4993 18 0.4971 0.4971 19 0.4660 0.4660 20 0.4626 0.4626 21 0.4577 0.4577 22 0.4537 0.4537 23 0.4511 0.4511 24 0.4493 0.4493 25 0.4381 0.4381 26 0.4337 0.4337 27 0.4314 0.4314 28 0.4219 0.4219 29 0.3939 0.3939 30 0.3917 0.3917 31 0.3846 0.3846 32 0.3821 0.3821 33 0.3744 0.3744 34 0.3712 0.3712 35 0.3545 0.3545 36 0.3429 0.3429 37 0.3424 0.3424 38 0.3375 0.3375 39 0.3310 0.3310 40 0.3229 0.3229 41 0.2894 0.2894 42 0.2851 0.2851 43 0.2775 0.2775 44 0.2703 0.2703 POC #1 The Facility PASSED The Facility PASSED. Flow(CFS) Predev Dev Percentage Pass/Fail 0.2229 659 659 100 Pass 0.2305 607 607 100 Pass 0.2382 563 563 100 Pass 0.2458 524 524 100 Pass 0.2534 481 481 100 Pass 0.2611 447 447 100 Pass 0.2687 413 413 100 Pass 0.2764 366 366 100 Pass 0.2840 335 335 100 Pass 0.2916 301 301 100 Pass 0.2993 269 269 100 Pass 0.3069 257 257 100 Pass 0.3146 229 229 100 Pass 0.3222 208 208 100 Pass 0.3299 188 188 100 Pass 0.3375 160 160 100 Pass 0.3451 148 148 100 Pass 0.3528 143 143 100 Pass 0.3604 134 134 100 Pass 0.3681 128 128 100 Pass 0.3757 114 114 100 Pass 0.3834 105 105 100 Pass 0.3910 98 98 100 Pass 0.3986 90 90 100 Pass 0.4063 87 87 100 Pass 0.4139 80 80 100 Pass 0.4216 74 74 100 Pass 0.4292 70 70 100 Pass 0.4368 65 65 100 Pass 0.4445 61 61 100 Pass 0.4521 51 51 100 Pass 0.4598 45 45 100 Pass 0.4674 38 38 100 Pass 0.4751 34 34 100 Pass 0.4827 30 30 100 Pass 0.4903 30 30 100 Pass 0.4980 30 30 100 Pass 0.5056 28 28 100 Pass 0.5133 27 27 100 Pass 0.5209 26 26 100 Pass 0.5285 24 24 100 Pass 0.5362 21 21 100 Pass 0.5438 19 19 100 Pass 0.5515 16 16 100 Pass 0.5591 16 16 100 Pass 0.5668 14 14 100 Pass 0.5744 12 12 100 Pass 0.5820 11 11 100 Pass 0.5897 8 8 100 Pass 0.5973 7 7 100 Pass 0.6050 7 7 100 Pass 0. 6126 7 7 100 Pass 0. 6203 6 6 100 Pass 0. 6279 6 6 100 Pass 0. 6355 6 6 100 Pass 0. 6432 6 6 100 Pass 0.6508 6 6 100 Pass 0. 6585 6 6 100 Pass 0. 6661 6 6 100 Pass 0. 6737 5 5 100 Pass 0. 6814 4 4 100 Pass 0.6890 4 4 100 Pass 0. 6967 4 4 100 Pass 0.7043 4 4 100 Pass 0.7120 4 4 100 Pass 0.7196 4 4 100 Pass 0.7272 4 4 100 Pass 0.7349 3 3 100 Pass 0.7425 2 2 100 Pass 0.7502 2 2 100 Pass 0.7578 2 2 100 Pass 0.7655 2 2 100 Pass 0.7731 2 2 100 Pass 0.7807 2 2 100 Pass 0.7884 2 2 100 Pass 0.7960 2 2 100 Pass 0.8037 2 2 100 Pass 0.8113 2 2 100 Pass 0.8189 2 2 100 Pass 0.8266 2 2 100 Pass 0.8342 2 2 100 Pass 0.8419 2 2 100 Pass 0.8495 2 2 100 Pass 0.8572 2 2 100 Pass 0.8648 2 2 100 Pass 0.8724 2 2 100 Pass 0.8801 2 2 100 Pass 0.8877 2 2 100 Pass 0.8954 2 2 100 Pass 0. 9030 2 2 100 Pass 0. 9106 2 2 100 Pass 0.9183 2 2 100 Pass 0.9259 1 1 100 Pass 0. 9336 1 1 100 Pass 0. 9412 1 1 100 Pass 0. 9489 1 1 100 Pass 0. 9565 1 1 100 Pass 0. 9641 1 1 100 Pass 0. 9718 1 1 100 Pass 0. 9794 1 1 100 Pass Water Quality HMP Flow and Volume for POC 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. J Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/6/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name Proposed Catch Basin #1 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .0458 Impervious Land Use Acres SIDEWALKS FLAT 0.0034 Element Flows To: Surface Interflow Groundwater Name Proposed Catch Basin #1 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .0458 Impervious Land Use Acres SIDEWALKS FLAT 0.0034 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.017561 5 year 0.024365 10 year 0.029332 25 year 0.036152 50 year 0.041638 100 year 0.047481 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.017561 5 year 0.024365 10 year 0.029332 25 year 0.036152 50 year 0.041638 100 year 0.047481 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 0.060 0.060 1958 0.015 0.015 1959 0.028 0.028 1960 0.022 0.022 1961 0.013 0.013 1962 0.023 0.023 1963 0.017 0.017 1964 0.018 0.018 1965 0.013 0.013 1966 0.011 0.011 1967 0.039 0.039 1968 0.021 0.021 1969 0.019 0.019 1970 0.016 0.016 1971 0.015 0.015 1972 0.026 0.026 1973 0.023 0.023 1974 0.017 0.017 1975 0.024 0.024 1976 0.023 0.023 1977 0.024 0.024 1978 0.010 0.010 1979 0.017 0.017 1980 0.012 0.012 1981 0.021 0.021 1982 0.015 0.015 1983 0.018 0.018 1984 0.023 0.023 1985 0.010 0.010 1986 0.012 0.012 1987 0.015 0.015 1988 0.021 0.021 1989 0.013 0.013 1990 0.011 0.011 1991 0.011 0.011 1992 0.023 0.023 1993 0.015 0.015 1994 0.011 0.011 1995 0.024 0.024 1996 0.019 0.019 1997 0.020 0.020 1998 0.016 0.016 1999 0.019 0.019 2000 0.032 0.032 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0596 0.0596 2 0.0388 0.0388 3 0.0317 0.0317 4 0.0279 0.0279 5 0.0264 0.0264 6 0.0239 0.0239 7 0.0237 0.0237 8 0.0236 0.0236 9 0.0232 0.0232 10 0.0231 0.0231 i ro w U) 0 U) U) U) U) U) U) U) U) U) 0 U) U) U) U) w U) U) w U) 0 0 0 U) U) U) U) U) U) U) O 0 l0 r-I r-I m 00 m T O W r- ld C' N ld N w 'T M M r- Ln O O1 W m 00 -cl, ri C- C- N 0D ro U) U) U) M U) U) M M U) M U) U) O U) U) U) U) U) U) U) U) U) U) U) U) U) U) U) U) M M N N ri O O M dl dl 00 i` i` i` r- l0 l0 Ln Ln Ln Ln V' C M N N ri r1 rl rl O O O m a m ro ro ro ro ro ro ro ro ro ro ro ro ro ro m m b ro ro ro ro ro m ro m ro ro ro NNNNNNN .-i r-i ri r-I r-i .-i r-i r-i .-i r-Arl ri rir-A r-i r-i r-i r-i rl .-Ir-i .-i rHi ir-I r10 a a as aaaa as a, aaa a a aaaa a a a, as wa wa O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O U) b1 O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O ro 0 0 0 0 O O O O O O O O O O O O O O O O O O O O O O O O O O N 0 0 0 0 0 0 0 0 0 0 O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O a y --I LnO 0i` -zzrON C- m mk.0 r-1 Ln 0 r- Ln Ln l0 U 1-1 i` G' 0 m Ln N O l0 G' N O m i` Ln C' N N ri 0 0l M m m N 0 r m l0 Ln C' C 31 M M M N N N N N r-I r-1 r-1 ri ri r-1 r-1 r-1 dl m O r- i` C- ld Ln Ln W W U) U) O 0 ld rl r-1 m 00 d> C O co r- lO N l0 N N V (1) M C- Ln (D 0) CO 01 O C ri C- C- N co a' a' O MMNNr-I O Om Ol a) cc) [- [- [- I- l0 l0 Ln Ln Ln Ln d' C M N Nrl rl rl r-i 00001 a a N N N N N N N ri ri 1-1 r-I 1-1 1-1 r-i r-i -i ri r1 r1 ri r1 ri ri ri ri r1 r1 rl rl 1-1 ri '-1 r-i O U r-I Ln O C' 0 r- C' 07 N r- 01 m l0 ri Ln 0 r- Ln Ln l0 00000000000000000000000 CD 0000000000 r- (D co Ln N 00 l0 d' N 000 i` Ln T (N (N r-100) c) m m N 0 r- m 10 4-) 4.) a Ln C d' �T M M M N N N N N ri ri r-i ri ri ri r-1 -4 M M M i` i` i` l0 Ln Ln 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 •rl •rl H r-1 •rl rl Cq ri N N V 0DriC00 r-i cm -1 1, co -Ic CC) r -V 00 -1 00 -1crODriv C` rlv' rr-( 31: 44 00 01 a) 01 O O 0 r-i r-i r-i N N N (M M M G' C G' Ln Ln Ln l0 l0 lO i` i` i` M O O O 0 ri r1 ri r-1 r-i r-i ri ri r-i r-i ri r1 .-i ri ri ri r-i r-i f-i r-i ri r-i r-i ri r-i U N a) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 rlNm ":v Ln ld r- 00 m0rINMC' Ln l0 r- 0D 010 r1N M ;a, Ul 110 i` 0 d10 r-1N (M C' 0 ,0 4 ri r-I ri r-Iriri ri ri r-i r-i N N N N N N N N N N (n M M M M M M ('•) m m J' d' :T a H H G400000000000000000000000000000 0.0184 52 52 100 Pass 0.0187 48 48 100 Pass 0.0191 41 41 100 Pass 0.0194 36 36 100 Pass 0.0197 31 31 100 Pass 0.0201 28 28 100 Pass 0.0204 28 28 100 Pass 0.0207 27 27 100 Pass 0.0211 24 24 100 Pass 0.0214 22 22 100 Pass 0.0217 21 21 100 Pass 0.0221 20 20 100 Pass 0.0224 19 19 100 Pass 0.0227 17 17 100 Pass 0.0231 14 14 100 Pass 0.0234 12 12 100 Pass 0.0237 10 10 100 Pass 0.0240 8 8 100 Pass 0.0244 8 8 100 Pass 0.0247 8 8 100 Pass 0.0250 7 7 100 Pass 0.0254 7 7 100 Pass 0.0257 7 7 100 Pass 0.0260 7 7 100 Pass 0.0264 7 7 100 Pass 0.0267 6 6 100 Pass 0.0270 6 6 100 Pass 0.0274 6 6 100 Pass 0.0277 6 6 100 Pass 0.0280 4 4 100 Pass 0.0284 4 4 100 Pass 0.0287 4 4 100 Pass 0.0290 3 3 100 Pass 0.0294 3 3 100 Pass 0.0297 3 3 100 Pass 0.0300 3 3 100 Pass 0.0304 3 3 100 Pass 0.0307 3 3 100 Pass 0.0310 3 3 100 Pass 0.0313 3 3 100 Pass 0.0317 2 2 100 Pass 0.0320 2 2 100 Pass 0.0323 2 2 100 Pass 0.0327 2 2 100 Pass 0.0330 2 2 100 Pass 0.0333 2 2 100 Pass 0.0337 2 2 100 Pass 0.0340 2 2 100 Pass 0.0343 2 2 100 Pass 0.0347 2 2 100 Pass 0.0350 2 2 100 Pass 0.0353 2 2 100 Pass 0.0357 2 2 100 Pass 0.0360 2 2 100 Pass 0.0363 2 2 100 Pass 0.0367 2 2 100 Pass 0.0370 2 2 100 Pass 0.0373 2 2 100 Pass 0.0377 2 2 100 Pass 0.0380 2 2 100 Pass 0.0383 2 2 100 Pass 0.0387 2 2 100 Pass 0.0390 1 1 100 Pass 0.0393 1 1 100 Pass 0.0396 1 1 100 Pass 0.0400 1 1 100 Pass 0.0403 1 1 100 Pass 0.0406 1 1 100 Pass 0.0410 1 1 100 Pass 0.0413 1 1 100 Pass 0.0416 1 1 100 Pass i Water Quality BMP Flow and Volume for POc 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/6/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name Catch Basin #2 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .0974 Impervious Land Use Acres SIDEWALKS FLAT 0.0076 Element Flows To: Surface Interflow Groundwater Name Catch Basin #2 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .0974 Impervious Land Use Acres SIDEWALKS FLAT 0.0076 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.037573 5 year 0.052085 10 year 0.062674 25 year 0.077204 50 year 0.088886 100 year 0.101323 Mitigated. POC #1 Flow Frequency Return Periods for Miti g Return Period Flow(cfs) 2 year 0.037573 5 year 0.052085 10 year 0.062674 25 year 0.077204 50 year 0.088886 100 year 0.101323 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 0.127 0.127 1958 0.031 0.031 1959 0.060 0.060 1960 0.047 0.047 1961 0.027 0.027 1962 0.049 0.049 1963 0.037 0.037 1964 0.038 0.038 1965 0.028 0.028 1966 0.024 0.024 1967 0.083 0.083 1968 0.045 0.045 1969 0.041 0.041 1970 0.035 0.035 1971 0.033 0.033 1972 0.057 0.057 1973 0.049 0.049 1974 0.037 0.037 1975 0.050 0.050 1976 0.050 0.050 1977 0.051 0.051 1978 0.022 0.022 1979 0.036 0.036 1980 0.025 0.025 1981 0.045 0.045 1982 0.033 0.033 1983 0.038 0.038 1984 0.049 0.049 1985 0.021 0.021 1986 0.025 0.025 1987 0.033 0.033 1988 0.045 0.045 1989 0.028 0.028 1990 0.023 0.023 1991 0.023 0.023 1992 0.048 0.048 1993 0.031 0.031 1994 0.025 0.025 1995 0.051 0.051 1996 0.041 0.041 1997 0.043 0.043 1998 0.034 0.034 1999 0.040 0.040 2000 0.068 0.068 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.1273 0.1273 2 0.0828 0.0828 3 0.0677 0.0677 4 0.0596 0.0596 5 0.0565 0.0565 6 0.0512 0.0512 7 0.0507 0.0507 8 0.0505 0.0505 9 0.0495 0.0495 10 0.0495 0.0495 11 0.0491 0.0491 12 0.0491 0.0491 13 0.0483 0.0483 14 0.0472 0.0472 15 0.0452 0.0452 16 0.0446 0.0446 17 0.0446 0.0446 18 0.0425 0.0425 19 0.0414 0.0414 20 0.0405 0.0405 21 0.0402 0.0402 22 0.0379 0.0379 23 0.0377 0.0377 24 0.0372 0.0372 25 0.0367 0.0367 26 0.0356 0.0356 27 0.0347 0.0347 28 0.0339 0.0339 29 0.0330 0.0330 30 0.0327 0.0327 31 0.0327 0.0327 32 0.0315 0.0315 33 0.0311 0.0311 34 0.0278 0.0278 35 0.0276 0.0276 36 0.0273 0.0273 37 0.0255 0.0255 38 0.0253 0.0253 39 0.0245 0.0245 40 0.0237 0.0237 41 0.0230 0.0230 42 0.0229 0.0229 43 0.0218 0.0218 44 0.0209 0.0209 POC #1 The Facility PASSED The Facility PASSED. Flow(CFS) Predev Dev Percentage Pass/Fail 0.0188 511 511 100 Pass 0.0195 475 475 100 Pass 0.0202 441 441 100 Pass 0.0209 405 405 100 Pass 0.0216 381 381 100 Pass 0.0223 357 357 100 Pass 0.0230 324 324 100 Pass 0.0237 289 289 100 Pass 0.0245 263 263 100 Pass 0.0252 247 247 100 Pass 0.0259 230 230 100 Pass 0.0266 212 212 100 Pass 0.0273 188 188 100 Pass 0.0280 171 171 100 Pass 0.0287 155 155 100 Pass 0.0294 140 140 100 Pass 0.0301 128 128 100 Pass 0.0308 125 125 100 Pass 0.0315 115 115 100 Pass 0.0322 107 107 100 Pass 0.0329 99 99 100 Pass 0.0337 94 94 100 Pass 0.0344 89 89 100 Pass 0.0351 80 80 100 Pass 0.0358 72 72 100 Pass 0.0365 70 70 100 Pass 0.0372 68 68 100 Pass 0.0379 61 61 100 Pass 0.0386 56 56 100 Pass 0.0393 53 53 100 Pass 0.0400 48 48 100 Pass 0.0407 41 41 100 Pass 0. 0414 37 37 100 Pass 0.0422 31 31 100 Pass 0. 0429 28 28 100 Pass 0.0436 28 28 100 Pass 0. 0443 27 27 100 Pass 0.0450 25 25 100 Pass 0.0457 22 22 100 Pass 0.0464 21 21 100 Pass 0.0471 20 20 100 Pass 0.0478 19 19 100 Pass 0.0485 17 17 100 Pass 0.0492 14 14 100 Pass 0.0499 12 12 100 Pass 0. 0506 11 11 100 Pass 0.0514 8 8 100 Pass 0.0521 8 8 100 Pass 0.0528 8 8 100 Pass 0.0535 7 7 100 Pass 0.0542 7 7 100 Pass 0.0549 7 7 100 Pass 0.0556 7 7 100 Pass 0.0563 7 7 100 Pass 0.0570 6 6 100 Pass 0.0577 6 6 100 Pass 0.0584 6 6 100 Pass 0.0591 6 6 100 Pass 0.0599 4 4 100 Pass 0.0606 4 4 100 Pass 0.0613 4 4 100 Pass 0.0620 3 3 100 Pass 0.0627 3 3 100 Pass 0.0634 3 3 100 Pass 0.0641 3 3 100 Pass 0.0648 3 3 100 Pass 0.0655 3 3 100 Pass 0.0662 3 3 100 Pass 0.0669 3 3 100 Pass 0.0676 3 3 100 Pass 0.0684 2 2 100 Pass 0.0691 2 2 100 Pass 0.0698 2 2 100 Pass 0.0705 2 2 100 Pass 0.0712 2 2 100 Pass 0.0719 2 2 100 Pass 0.0726 2 2 100 Pass 0.0733 2 2 100 Pass 0.0740 2 2 100 Pass 0.0747 2 2 100 Pass 0.0754 2 2 100 Pass 0.0761 2 2 100 Pass 0.0768 2 2 100 Pass 0.0776 2 2 100 Pass 0.0783 2 2 100 Pass 0.0790 2 2 100 Pass 0.0797 2 2 100 Pass 0.0804 2 2 100 Pass 0.0811 2 2 100 Pass 0.0818 2 2 100 Pass 0.0825 2 2 100 Pass 0.0832 1 1 100 Pass 0.0839 1 1 100 Pass 0.0846 1 1 100 Pass 0.0853 1 1 100 Pass 0.0861 1 1 100 Pass 0.0868 1 1 100 Pass 0.0875 1 1 100 Pass 0.0882 1 1 100 Pass 0.0889 1 1 100 Pass Water Quality BMP Flow and Volume for POC 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/6/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name Catch Basin #3 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .1441 Impervious Land Use Acres ROOF TOPS FLAT 0.04 SIDEWALKS FLAT 0.0039 Element Flows To: Surface Interflow Groundwater Name Catch Basin #3 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .1441 Impervious Land Use Acres ROOF TOPS FLAT 0.04 SIDEWALKS FLAT 0.0039 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.075166 5 year 0.100769 10 year 0.119359 25 year 0.144783 I 50 year 0.165172 100 year 0.186845 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.075166 5 year 0.100769 10 year 0.119359 25 year 0.144783 50 year 0.165172 100 year 0.186845 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 0.237 0.237 1958 0.063 0.063 1959 0.112 0. 112 1960 0.091 0.091 1961 0.056 0.056 1962 0.093 0.093 1963 0.076 0.076 1964 0.075 0.075 1965 0.056 0.056 1966 0.049 0.049 1967 0.155 0. 155 1968 0.085 0.085 1969 0.078 0.078 1970 0.070 0.070 1971 0.066 0.066 1972 0.107 0.107 1973 0.094 0.094 1974 0.072 0.072 1975 0.098 0.098 1976 0.098 0.098 1977 0.096 0.096 1978 0.046 0.046 1979 0.075 0.075 1980 0.057 0.057 1981 0.088 0.088 1982 0.064 0.064 1983 0.077 0.077 1984 0.100 0.100 1985 0.045 0.045 1986 0.060 0.060 1987 0.066 0.066 1988 0.087 0.087 1989 0.059 0.059 1990 0.048 0.048 1991 0.053 0.053 1992 0.094 0.094 1993 0.064 0.064 1994 0.052 0.052 1995 0.099 0.099 1996 0.079 0.079 1997 0.084 0.084 1998 0.071 0.071 1999 0.078 0.078 2000 0.128 0.128 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.2372 0.2372 2 0.1546 0.1546 3 0.1285 0.1285 4 0.1123 0.1123 5 0.1072 0.1072 6 0.1000 0.1000 7 0.0994 0.0994 8 0.0985 0.0985 000000000000000000000000000 ftl F-3 H ro X' J�` J�` � k" W W W W W W W W W W NNNNNNNNNNF- I-- F- F- -- I- - -- I- �-- -'p F .7 ,3' O W NI O19C0 �161CnX, W NF-' O1000 ­101Cn 't�' WNF- 0 ',DOD -J01Cnaa W NNO 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (D (D C) rnrnrnrnrnrnrnrncncncncncrnCncn (naa�. Jaaaa a� wwS F- lfl m -1 Cn aA W N (D lD m 0) Cn WA W " 0 1,0 J M Cn N F- O m J.-. KJ t1 =k I-' m Cn NCp O1 X, m (n N1061 W O m Cn N IO m W 0 �7IrlN l0 m C) D) 0) N ro n n In P- P. -- N F, P. P. O O O o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 �1 m OD lO l0 F- N N N N N W W W OA Cn Ul a) ct (nOmNOOO N W W ACr) 000NaACnQ0MCP00ND� mN) MCD k OOOo00o0000o000OOOo000o0000000000000 J Ul w N J N 'P w m JA m Al, JP xA aA (n (n (n (n (n (n Cn M M M M M J J _l J J J J J J J m m m m l0 (0 (0 l0 l0 l0 Q. ro ro CT1 M J m N N (n 0) 0') m Cfl N X�- aA OI OI O F� F- ., tl Cn -1 m m lfl 'A CTt m m O W 0A Z� Cnm (D o (n CO 0') Ul Cn m N Ol M l0 J CD W 0 IA lA aA ',D (DO (O --IF� F� W (n dl N F-' J N cn CD (n cn C-J t J �l m m l0 W F� F- F- H Fl N N N N N W W W .P r- .A Cn cn a) CI C7 CJ (-n O CC) NmOHM W W aP M m O N xA Cn W N (n m N m N 0l O (D J Cn W N -_l m m Ol J N w N 1? W m �A m J Q ro (D Ft F-' N F-' F� F� F- F� F- H F-' F✓ F-I F- H F- F- n 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o O o (p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o p (t 0) o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o O o 0 0 0 0 0 0 0 0 0 0 0 0 0 (D o00000000000000000000000000000000000 roro �0 roro oro rO U roro h7h7ro ro ob o h7n7ro �o R7 h7rd ro no aAa�- 0A -A (n (n (ncnCnCn (nMMMMMJvJJJJJJJJmmmml0lfl (O (0 \0Cfl a a a a a a a a a a a a a a a a a a a a a a a a a a a ro (n M --) m N N (n 0) M m W N 4A -A M M 0 H " d P (n -1 m m Q0 a� (n ON m o W C (n m (7 (n to fn Cn (A (J7 (n (n (n [n (n (n (A w m Cn w m w w m w ww w wD) 0 (n m m (n Cn CO N m m lfl J O w CD 'G Jp X, CD m (0 J F- H W F� .A N l0 Cn m N F-' �A �] N fA Ul UI Cn fA (!1 (n (n (n w w N w w (A (A (n (n Cn (n (n (n UT (n (A (n fn N N a F' 0.0724 72 72 100 Pass 0.0737 66 66 100 Pass 0.0750 59 59 100 Pass 0.0762 57 57 100 Pass 0.0775 51 51 100 Pass 0.0788 45 45 100 Pass 0.0801 40 40 100 Pass 0.0814 32 32 100 Pass 0.0827 31 31 100 Pass 0.0840 30 30 100 Pass 0.0853 28 28 100 Pass 0.0866 28 28 100 Pass 0.0878 27 27 100 Pass 0.0891 24 24 100 Pass 0.0904 21 21 100 Pass 0.0917 19 19 100 Pass 0.0930 19 19 100 Pass 0.0943 16 16 100 Pass 0.0956 14 14 100 Pass 0.0969 13 13 100 Pass 0.0982 12 12 100 Pass 0.0994 9 9 100 Pass 0.1007 8 8 100 Pass 0. 1020 7 7 100 Pass 0.1033 7 7 100 Pass 0.1046 7 7 100 Pass 0.1059 7 7 100 Pass 0.1072 7 7 100 Pass 0. 1085 6 6 100 Pass 0.1098 6 6 100 Pass 0.1110 6 6 100 Pass 0.1123 6 6 100 Pass 0.1136 5 5 100 Pass 0.1149 5 5 100 Pass 0.1162 4 4 100 Pass 0. 1175 4 4 100 Pass 0.1188 4 4 100 Pass 0.1201 3 3 100 Pass 0. 1214 3 3 100 Pass 0.1226 3 3 100 Pass 0. 1239 3 3 100 Pass 0.1252 3 3 100 Pass 0.1265 3 3 100 Pass 0. 1278 3 3 100 Pass 0.1291 2 2 100 Pass 0.1304 2 2 100 Pass 0. 1317 2 2 100 Pass 0.1330 2 2 100 Pass 0. 1342 2 2 100 Pass 0. 1355 2 2 100 Pass 0. 1368 2 2 100 Pass 0. 1381 2 2 100 Pass 0. 1394 2 2 100 Pass 0. 1407 2 2 100 Pass 0.1420 2 2 100 Pass 0. 1433 2 2 100 Pass 0. 1446 2 2 100 Pass 0. 1458 2 2 100 Pass 0.1471 2 2 100 Pass 0.1484 2 2 100 Pass 0. 1497 2 2 100 Pass 0.1510 2 2 100 Pass 0.1523 2 2 100 Pass 0.1536 2 2 100 Pass 0. 1549 1 1 100 Pass 0.1562 1 1 100 Pass 0.1574 1 1 100 Pass 0.1587 1 1 100 Pass 0.1600 1 1 100 Pass 0.1613 1 1 100 Pass 0.1626 1 1 100 Pass n 1FZQ 1 1 1nn n_-_ 0.1652 1 1 100 Pass Water Quality BMP Flow and Volume for POC 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. i Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/6/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name Catch Basin #4 Bypass: No Groundwater: No Pervious Land Use Acres A B, Lawn, Mod .1108 Impervious Land Use Acres ROOF TOPS FLAT 0.0249 SIDEWALKS FLAT 0.1129 Element Flows To: Surface Interflow Groundwater Name Catch Basin #4 Bypass: No GroundWater: No Pervious Land Use Acres A B, Lawn, Mod .1108 Impervious Land Use Acres ROOF TOPS FLAT 0.0249 SIDEWALKS FLAT 0.1129 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS ?low Frequency Return Periods for Predeveloped. POC #1 .Return Period Flow(cfs) 2 year 0.120764 i year 0.154375 .0 year 0.178373 25 year 0.210739 50 year 0.236379 100 year 0.263368 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0. 120764 5 year 0. 154375 10 year 0. 178373 25 year 0.210739 50 year 0.236379 100 year 0.263368 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 0.338 0.338 1958 0.121 0.121 1959 0.163 0.163 1960 0.136 0. 136 1961 0.092 0.092 1962 0.137 0. 137 1963 0.124 0. 124 1964 0.117 0.117 1965 0.099 0.099 1966 0.081 0.081 1967 0.221 0.221 1968 0.127 0.127 1969 0.118 0.118 1970 0.115 0.115 1971 0.107 0. 107 1972 0.158 0.158 1973 0.140 0.140 1974 0.111 0.111 1975 0.152 0.152 1976 0.155 0.155 1977 0.140 0.140 1978 0.081 0.081 1979 0.128 0. 128 1980 0.104 0.104 1981 0.140 0. 140 1982 0.100 0. 100 1983 0.127 0. 127 1984 0.164 0.164 1985 0.079 0.079 1986 0.118 0. 118 1987 0.107 0.107 1988 0.131 0.131 1989 0.100 0.100 1990 0.081 0.081 1991 0.100 0.100 1992 0.144 0.144 1993 0.104 0.104 1994 0.092 0.092 1995 0.152 0.152 1996 0.117 0.117 1997 0.133 0.133 1998 0.123 0.123 1999 0.120 0.120 2000 0.189 0.189 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.3382 0.3382 2 0.2211 0.2211 3 0.1891 0.1891 4 0.1640 0.1640 5 0.1632 0.1632 6 0.1577 0.1577 7 0.1547 0.1547 8 0.1518 0.1518 9 0.1516 0.1516 10 0.1442 0.1442 11 0.1401 0.1401 12 0.1399 0.1399 13 0.1395 0.1395 14 0.1373 0.1373 15 0.1359 0.1359 16 0.1332 0.1332 17 0.1308 0.1308 18 0.1280 0.1280 19 0.1271 0.1271 20 0.1269 0.1269 21 0.1241 0.1241 22 0.1226 0.1226 23 0.1212 0.1212 24 0.1203 0.1203 25 0.1178 0.1178 26 0.1177 0.1177 27 0.1173 0.1173 28 0.1173 0.1173 29 0.1152 0.1152 30 0.1113 0.1113 31 0.1071 0.1071 32 0.1069 0. 1069 33 0.1045 0.1045 34 0.1040 0.1040 35 0.1004 0.1004 36 0.1002 0.1002 37 0.0999 0.0999 38 0.0988 0.0988 39 0.0920 0.0920 40 0.0919 0.0919 41 0.0809 0.0809 42 0.0808 0.0808 43 0.0806 0.0806 44 0.0793 0.0793 POC #1 The Facility PASSED The Facility PASSED. Flow(CFS) Predev Dev Percentage Pass/Fail 0.0604 884 884 100 Pass 0.0622 802 802 100 Pass 0.0639 740 740 100 Pass 0.0657 695 695 100 Pass 0.0675 653 653 100 Pass 0.0693 605 605 100 Pass 0.0710 559 559 100 Pass 0.0728 518 518 100 Pass 0.0746 469 469 100 Pass 0.0764 433 433 100 Pass 0.0782 395 395 100 Pass 0.0799 348 348 100 Pass 0.0817 307 307 100 Pass 0.0835 272 272 100 Pass 0.0853 258 258 100 Pass 0.0870 233 233 100 Pass 0.0888 204 204 100 Pass 0.0906 184 184 100 Pass 0.0924 173 173 100 Pass 0.0942 161 161 100 Pass 0.0959 151 151 100 Pass 0.0977 143 143 100 Pass 0.0995 135 135 100 Pass 0.1013 127 127 100 Pass 0.1030 117 117 100 Pass 0.1048 103 103 100 Pass 0. 1066 97 97 100 Pass 0.1084 91 91 100 Pass 0.1102 86 86 100 Pass 0.1119 78 78 100 Pass 0.1137 73 73 100 Pass 0.1155 67 67 100 Pass 0.1173 62 62 100 Pass 0.1190 57 57 100 Pass 0.1208 53 53 100 Pass 0.1226 45 45 100 Pass 0.1244 39 39 100 Pass 0.1262 38 38 100 Pass 0. 1279 33 33 100 Pass 0. 1297 31 31 100 Pass 0.1315 30 30 100 Pass 0. 1333 30 30 100 Pass 0. 1350 28 28 100 Pass 0. 1368 25 25 100 Pass 0. 1386 23 23 100 Pass 0. 1404 19 19 100 Pass 0. 1422 18 18 100 Pass 0.1439 17 17 100 Pass 0.1457 15 15 100 Pass 0.1475 14 14 100 Pass 0.1493 13 13 100 Pass 0. 1510 12 12 100 Pass 0. 1528 9 9 100 Pass 0. 1546 9 9 100 Pass 0. 1564 8 8 100 Pass 0.1582 7 7 100 Pass 0.1599 7 7 100 Pass 0.1617 7 7 100 Pass 0.1635 6 6 100 Pass 0. 1653 5 5 100 Pass 0. 1670 5 5 100 Pass 0.1688 5 5 100 Pass 0.1706 5 5 100 Pass 0. 1724 5 5 100 Pass 0. 1742 4 4 100 Pass 0.1759 4 4 100 Pass 0.1777 4 4 100 Pass 0. 1795 4 4 100 Pass 0. 1813 3 3 100 Pass 0. 1830 3 3 100 Pass 0.1848 3 3 100 Pass 0.1866 3 3 100 Pass 0. 1884 3 3 100 Pass 0. 1902 2 2 100 Pass 0. 1919 2 2 100 Pass 0.1937 2 2 100 Pass 0. 1955 2 2 100 Pass 0. 1973 2 2 100 Pass 0.1990 2 2 100 Pass 0.2008 2 2 100 Pass 0.2026 2 2 100 Pass 0.2044 2 2 100 Pass 0.2062 2 2 100 Pass 0.2079 2 2 100 Pass 0.2097 2 2 100 Pass 0.2115 2 2 100 Pass 0.2133 2 2 100 Pass 0.2150 2 2 100 Pass 0.2168 2 2 100 Pass 0.2186 2 2 100 Pass 0.2204 2 2 100 Pass 0.2222 1 1 100 Pass 0.2239 1 1 100 Pass 0.2257 1 1 100 Pass 0.2275 1 1 100 Pass 0.2293 1 1 100 Pass 0.2310 1 1 100 Pass 0.2328 1 1 100 Pass L n ')ZA G 0.2364 1 1 100 Pass Water Quality BMP Flow and Volume for POC 1. On-line facility volume: 0 acre-feet on-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. Western Washington Hydrology Model PROJECT REPORT Project Name: default Site Address: 6520 East State Highway 106 City Union Report Date 8/6/2010 Gage Quilcene Data Start 1955/10/01 Data End 1999/09/30 Precip Scale: 1.44 WWHM3 Version: PREDEVELOPED LAND USE Name Ex. CB #1 Bypass: No Groundwater: No Pervious Land Use Acres A B, Forest, Mod .9427 Impervious Land Use Acres PARKING FLAT 0.3805 Element Flows To: Surface Interflow Groundwater Name Ex. CB #1 Bypass: No Groundwater: No Pervious Land Use Acres A B, Forest, Mod .9427 Impervious Land Use Acres PARKING FLAT 0.3805 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 teturn Period Flow(cfs) ? year 0.31278 i year 0.444104 10 year 0.545853 '.5 year 0. 692568 i0 year 0.815929 100 year 0.952116 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.31278 5 year 0.444104 10 year 0.545853 25 year 0. 692568 50 year 0.815929 100 year 0.952116 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1957 1.368 1.368 1958 0.313 0.313 1959 0.512 0.512 1960 0.372 0.372 1961 0.230 0.230 1962 0.435 0.435 1963 0.252 0.252 1964 0.318 0.318 1965 0.226 0.226 1966 0.198 0.198 1967 0.781 0.781 1968 0.357 0.357 1969 0.324 0.324 1970 0.263 0.263 1971 0.277 0.277 1972 0.478 0.478 1973 0.427 0.427 1974 0.314 0.314 1975 0.436 0.436 1976 0.377 0.377 1977 0.459 0.459 1978 0.196 0.196 1979 0.260 0.260 1980 0.222 0.222 1981 0.439 0.439 1982 0.266 0.266 1983 0.272 0.272 1984 0.384 0.384 1985 0.169 0.169 1986 0.262 0.262 1987 0.276 0.276 1988 0.379 0.379 1989 0.243 0.243 1990 0.201 0.201 1991 0.225 0.225 1992 0.408 0.408 1993 0.263 0.263 1994 0.215 0.215 1995 0.396 0.396 1996 0.335 0.335 1997 0.348 0.348 1998 0.251 0.251 1999 0.344 0.344 2000 0.562 0.562 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 1.3685 1.3685 2 0.7814 0.7814 3 0.5615 0.5615 4 0.5124 0.5124 5 0.4778 0.4778 6 0.4586 0.4586 7 0.4394 0.4394 8 0.4364 0.4364 9 0.4353 0.4353 10 0.4275 0.4275 11 0. 4079 0.4079 12 0.3964 0.3964 13 0.3840 0.3840 14 0.3790 0.3790 15 0.3772 0.3772 16 0.3723 0.3723 17 0.3570 0.3570 18 0.3478 0.3478 19 0.3442 0.3442 20 0.3352 0.3352 21 0.3235 0.3235 22 0.3183 0.3183 23 0.3143 0.3143 24 0.3128 0.3128 25 0.2772 0.2772 26 0.2758 0.2758 27 0.2719 0.2719 28 0.2660 0.2660 29 0.2635 0.2635 30 0.2632 0.2632 31 0.2625 0.2625 32 0.2596 0.2596 33 0.2518 0.2518 34 0.2514 0.2514 35 0.2428 0.2428 36 0.2295 0.2295 37 0.2260 0.2260 38 0.2250 0.2250 39 0.2225 0.2225 40 0.2145 0.2145 41 0.2012 0.2012 42 0.1975 0.1975 43 0.1961 0.1961 44 0.1693 0.1693 POC #1 The Facility PASSED The Facility PASSED. Flow(CFS) Predev Dev Percentage Pass/Fail 0.1564 770 770 100 Pass 0.1631 697 697 100 Pass 0. 1697 614 614 100 Pass 0.1764 533 533 100 Pass 0.1830 477 477 100 Pass 0.1897 429 429 100 Pass 0. 1964 362 362 100 Pass 0.2030 306 306 100 Pass 0.2097 269 269 100 Pass 0.2163 242 242 100 Pass 0.2230 211 211 100 Pass 0.2297 187 187 100 Pass 0.2363 154 154 100 Pass 0.2430 146 146 100 Pass 0.2497 136 136 100 Pass 0.2563 128 128 100 Pass 0.2630 117 117 100 Pass 0.2696 101 101 100 Pass 0.2763 93 93 100 Pass 0.2830 82 82 100 Pass 0.2896 76 76 100 Pass 0.2963 69 69 100 Pass 0.3030 66 66 100 Pass 0.3096 61 61 100 Pass 0.3163 55 55 100 Pass 0.3229 50 50 100 Pass 0.3296 43 43 100 Pass 0.3363 39 39 100 Pass 0.3429 36 36 100 Pass 0.3496 32 32 100 Pass 0.3563 27 27 100 Pass 0.3629 26 26 100 Pass 0.3696 24 24 100 Pass 0.3762 22 22 100 Pass 0.3829 20 20 100 Pass 0.3896 19 19 100 Pass 0.3962 18 18 100 Pass 0.4029 16 16 100 Pass 0.4095 15 15 100 Pass 0.4162 15 15 100 Pass 0.4229 15 15 100 Pass 0.4295 14 14 100 Pass 0.4362 11 11 100 Pass 0. 4429 9 9 100 Pass 0.4495 9 9 100 Pass 0. 4562 9 9 100 Pass 0.4628 8 8 100 Pass 0. 4695 7 7 100 Pass 0.4762 7 7 100 Pass 0.4828 6 6 100 Pass 0.4895 6 6 100 Pass 0.4962 6 6 100 Pass 0.5028 5 5 100 Pass 0.5095 5 5 100 Pass 0.5161 3 3 100 Pass 0.5228 3 3 100 Pass 0.5295 3 3 100 Pass 0.5361 3 3 100 Pass 0.5428 3 3 100 Pass 0.5494 3 3 100 Pass 0.5561 3 3 100 Pass 0.5628 2 2 100 Pass 0.5694 2 2 100 Pass 0.5761 2 2 100 Pass 0.5828 2 2 100 Pass 0.5894 2 2 100 Pass 0.5961 2 2 100 Pass 0. 6027 2 2 100 Pass 0.6094 2 2 100 Pass 0. 6161 2 2 100 Pass 0. 6227 2 2 100 Pass 0. 6294 2 2 100 Pass 0.6361 2 2 100 Pass 0. 6427 2 2 100 Pass 0. 6494 2 2 100 Pass 0. 6560 2 2 100 Pass 0.6627 2 2 100 Pass 0. 6694 2 2 100 Pass 0.6760 2 2 100 Pass 0. 6827 2 2 100 Pass 0. 6894 2 2 100 Pass 0. 6960 2 2 100 Pass 0.7027 2 2 100 Pass 0.7093 2 2 100 Pass 0.7160 2 2 100 Pass 0.7227 2 2 100 Pass 0.7293 2 2 100 Pass 0.7360 2 2 100 Pass 0.7426 2 2 100 Pass 0.7493 2 2 100 Pass 0.7560 2 2 100 Pass 0.7626 2 2 100 Pass 0.7693 2 2 100 Pass 0.7760 2 2 100 Pass 0.7826 1 1 100 Pass 0.7893 1 1 100 Pass 0.7959 1 1 100 Pass 0.8026 1 1 100 Pass 0.8093 1 1 100 Pass 0.8159 1 1 100 Pass Water Quality BMP Flow and Volume for POc 1. On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. APPENDIX 5 Basin Plan Blue Heron Resort& Condominium 9 Stormwater Site Plan JWM&A#10117 S. 33 T. 22N R. 3W, W.M. - �� •\\� B IN A2 PRO. CB—I O� 1', � BASIN T TAL AREA=0.489 PRO. CB -- \ -� TO qL I ACRES `� � TOTAL AREA= MPER IOUS AREA= 'ruriuirr- rrrrr _.`\ ` TOTAL IMPERVI1 051 ACRES 7% AL PERM S ARC= 201 ACRES TOTAL pERV10 OUS AREA=0 317 ACRES 8 AC �� 0. 8 ACRES _ ,.i \ US AREA=0.734 ACRES `„"„"`p`a�a„p� � , nnm nuunuurrlrr�uuuunnrum1 .............. nennnur �1`�,� da ur - � ,.-�`'' ,A` ���`'`., � •� r-�- ,`,,J��, BASIN I I IU .i—� '�0��- RR©. l;$—K. �, `'�•, `,1j�;1� '\ TOTAL ARE =1.2 i -u-LL]LL„JJ --> . `\ \ C\•'`�� ,t?i\�` p� TOTAL IMP RV 80ACRES i I BASINA EX. CB-I i � "\ �•� `\� 11 \ \ = TOTAL PERVIOUS AREAEA1, A0-006 CRES ES TOTT R ER 2.422 ACR S ! Rg`��j�� i \ TOTAL P P I OUS AREA 4 I \ ERV O S AREA= 984 q ACRES , •� ,I\? 1 ? ACRES !\ f•` i _ EX. CULVERT-I i!\ ,;iifAj CB+2 �-- 'i i�'Ennnnuunnlilrmntnnunummmmunrnnnrurnp f -_ 1 i (( i' ( X. LVERT-2 i►n -Q rrrg4piirurnuuiEano`$� - - - - - - ----- 1 uurunuunuquuuuumu�nunwrnuun unuumnn°O°ur nuuiunul�E g '..__ (;-i• \\, - r BASIN To—� - - - - / a I TOTAL MP RVIOUS ACRES ,��qi I, / TOTAL PERVIOUS AREgEg0.458 nc C >`RES � p II t `` �brrh/rrrrr� SCALE., 1'=60 FEET 0 20 40 80 NO DATE BY APPR REVISIONS Approved By D.O. o7�ae�io Civil-Municipal-Geotechnical•LandSurveying DESIGNED By DAE Blue Heron Resort RECREATION CENTER L.w. 07,I9/10 BASIN PLAN C.A.D.D.By DATE Jerome W. Morrissette & Associates Inc., P.S. "128 D7,28,D LO Mason county CHECKED BY DATE 10117 Blue Fleson\02 Drawings\Ol IWMBA Drawings\ 1700 Cooper Pt.Road S.W.g8-2,Olympia,Wa.98502-1110 Ph 360.352.9456 Fx 360.352.9990 01 Preliminary Drawings\10117 Blue Heron Sl,e Plan.dwg SHEET _L OF-L Blue Heron Resort- Stormwater Pollution Prevention Plan Stormwater Pollution Prevention Plan For Blue Heron Resort& Condominium Community Building Reconstruction Owner Developer Operator/Contractor Blue Heron Condominium Blue Heron Condominium T.B.D. 6520 East State Hwy 106 6520 East State Hwy 106 T.B.D. Union, WA 98592 Union, WA 98592 T.B.D. Project Site Location 6520 East State Highway 106,Union, WA Certified Erosion and Sediment Control Lead T.B.D. T.B.D. SWPPP Prepared By Jerome W. Morrissette&Associates Inc., P.S. 1700 Cooper Point Road SW,#B-2 Olympia, WA 98502 (360) 352-9456 Dan Osier, P.E. SWPPP Preparation Date August 6, 2010 Approximate Project Construction Dates Fall 2010 Summer 2011 i L Blue Heron Resort- Stormwater Pollution Prevention Plan Contents 1.0 Introduction...............................................................................................................................1 2.0 Site Description ........................................................................................................................3 2.1 Existing Conditions...........................................................................................................3 2.2 Proposed Construction Activities......................................................................................3 3.0 Construction Stormwater BMPs...............................................................................................5 3.1 The 12 BMP Elements.......................................................................................................5 3.1.1 Element#1 —Mark Clearing Limits...................................................................5 3.1.2 Element#2 —Establish Construction Access.....................................................5 3.1.3 Element#3 —Control Flow Rates.......................................................................6 3.1.4 Element#4—Install Sediment Controls.............................................................6 3.1.5 Element#5 — Stabilize Soils...............................................................................7 3.1.6 Element#6—Protect Slopes...............................................................................8 3.1.7 Element#7—Protect Drain Inlets.......................................................................9 3.1.8 Element#8 —Stabilize Channels and Outlets.....................................................9 3.1.9 Element#9—Control Pollutants.......................................................................10 3.1.10 Element #10—Control Dewatering.................................................................11 3.1.11 Element#11 —Maintain BMPs .......................................................................11 3.1.12 Element#12—Manage the Project..................................................................12 3.2 Site Specific BMPs..........................................................................................................15 3.3 Additional Advanced BMPs............................................................................................15 4.0 Construction Phasing and BMP Implementation ...................................................................16 5.0 Pollution Prevention Team ......................................................................................................18 5.1 Roles and Responsibilities...............................................................................................18 5.2 Team Members................................................................................................................19 6.0 Site Inspections and Monitoring.............................................................................................20 6.1 Site Inspection.................................................................................................................20 6.1.1 Site Inspection Frequency ................................................................................20 6.1.2 Site Inspection Documentation.........................................................................21 6.2 Stormwater Quality Monitoring......................................................................................21 6.2.1 Turbidity Sampling...........................................................................................21 6.2.2 pH Sampling.....................................................................................................22 7.0 Reporting and Recordkeeping ................................................................................................23 7.1 Recordkeeping.................................................................................................................23 7.1.1 Site Log Book...................................................................................................23 7.1.2 Records Retention.............................................................................................23 7.1.3 Access to Plans and Records............................................................................23 ii Blue Heron Resort- Stormwater Pollution Prevention Plan 7.1.4 Updating the SWPPP........................................................................................23 7.2 Reporting.........................................................................................................................24 7.2.1 Discharge Monitoring Reports .........................................................................24 7.2.2 Notification of Noncompliance........................................................................24 7.2.3 Permit Application and Changes......................................................................25 AppendixA—Site Plans.........................................................................................................26 Appendix B — Construction BMPs.........................................................................................27 Appendix C —Alternative BMPs............................................................................................28 Appendix D— General Permit ................................................................................................29 Appendix E— Site Inspection Forms (and Site Log)..............................................................30 iii Blue Heron Resort- Stormwater Pollution Prevention Plan 1.0 Introduction This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater permit requirements for the Blue Heron Resort& Condominium Community Building Reconstruction project near Union, Washington. The site is located at 6520 East State Highway 106, Union, Mason County. The existing site is 7.4 acres. The proposed development consists of the reconstruction of the Blue Heron Resort& Condominium Community Building, that was destroyed by fire in 2009. Construction activities will include the reconstruction of the destroyed building and other site improvements. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control(TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website on April 14, 2010. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit,Stormwater Management Manual for Western Washington (SWMMWW 2005) and in the Stormwater Management Manual for Eastern Washington (SWMMEW 2004). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in the each of the main sections are: ■ Section 1 —INTRODUCTION. This section provides a summary ar3' description of the project, and the organization of the SWPPP document. ■ Section 2—SITE DESCRIPTION. This section provides a detailed description of the existing site conditions,proposed construction activities, and calculated stormwater flow rates for existing conditions and post— construction conditions. 1 Blue Heron Resort- Stormwater Pollution Prevention Plan ■ Section 3—CONSTRUCTION BMPs. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP (SWMMEW 2004). ■ Section 4—CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This section provides a description of the timing of the BMP implementation in relation to the project schedule. ■ Section 5 —POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non-emergency), monitoring personnel, and the onsite temporary erosion and sedimentation control inspector ■ Section 6—INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements such as the parameters of concern to be monitored, sample locations, sample frequencies,and sampling methods for all stormwater discharge locations from the site. ■ Section 7—RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results,and changes to the implementation of certain BMPs due to site factors experienced during construction. Supporting documentation and standard forms are provided in the following Appendices: Appendix A—Site plans Appendix B—Construction BMPs Appendix C—Alternative Construction BMP list Appendix D—General Permit Appendix E—Site Log and Inspection Forms 2 Blue Heron Resort- Stormwater Pollution Prevention Plan 2.0 Site Description 2.1 Existing Conditions The proposed project is located at 6520 East State Highway 106,Union, Washington, in Mason County, Washington. The involved property includes the following assessor's tax parcel numbers: 322325010401, 322335242006, 322335289004. The subject site is located approximately 0.4 miles north of the intersection of E Dalby Road. The 7.4 acre property was developed in the 1970's and includes three condominium buildings, a combined office and shop,manager's residence, and several outbuildings. The property is bordered by undeveloped forested property to the west,by single family residences to the north and south, and Highway 106 to the east with Hood Canal approximately 150 feet beyond. Site topography slopes toward the east at an average slope of 5%. A 130-foot long by 12-foot wide grass bio-infiltration swale is located immediately east of the tennis courts on the westernmost portion of the property. The vegetation onsite consists of lawn, landscaping and trees. There are no sensitive or critical areas on site. The USDA Natural Resources Conservation Service Soil Survey of Mason County designates the onsite soils as Cloquallum silty clay loam, 5 to 15% slopes. The Cloquallum series is described as silty lacustrine deposits,with deep and moderately well drained soils. According the report prepared by Bradley-Noble Geotechnical Services,the soils encountered onsite are not consistent with the Soil Survey description, and exhibit the characteristics gravelly silty fine sands. Refer to the Appendices for the Soil Resource Report and geotechnical report. Stormwater runoff from the site is conveyed through a network of pipes and swales that crosses under Highway 106 and discharges into Hood Canal in two places. 2.2 Proposed Construction Activities The project consists of the reconstruction of the Blue Heron Resort& Condominium Community Building and related site work as shown on the project drawings. Construction activities include site preparation, TESC installation,building and utilities construction. Stormwater will flow to Hood Canal via proposed and existing pipes and swales. 3 Blue Heron Resort- Stormwater Pollution Prevention Plan The project area will be restored to its pre-construction condition, or better. ' The following summarizes details regarding site areas: ' ■ Total site area: 7.4 acres ■ Percent impervious area before construction: 23 % ■ Percent impervious area after construction: 23 % ' ■ Disturbed area during construction: 0.2 acres ■ Disturbed area that is characterized as impervious (i.e., access roads, staging,parking): 0.1 acres ■ 2-year stormwater runoff peak flow prior to construction (existing): 0.09 cfs ■ 10-year stormwater runoff peak flow prior to construction (existing): 0.13 cfs ■ 2-year stormwater runoff peak flow during construction: 0.09 cfs ■ 10-year stormwater runoff peak flow during construction: 0.13 cfs ■ 2-year stormwater runoff peak flow after construction: 0.09 cfs ■ 10-year stormwater runoff peak flow after construction: 0.13 cfs ' 4 Blue Heron Resort- Stormwater Pollution Prevention Plan 3.0 Construction Stormwater BMPs 3.1 The 12 BMP Elements 3.1.1 Element #1 —Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction,the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers,will be delineated on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: • No BMPs to be implemented Improvements will be staked. Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D),the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element#2—Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized,yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include: • Stabilized Construction Entrance (BMP C105) Alternate construction access BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D),the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the 5 Blue Heron Resort- Stormwater Pollution Prevention Plan alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.3 Element#3—Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The specific BMPs for flow control that shall be used on this project include: • Check Dams(BMP C207) • Straw Wattles(BMP C235) Alternate flow control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s)listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s)of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such,the project must comply with Minimum Requirement 7 (Ecology 2005). In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements(e.g. discharge to combined sewer systems). 3.1.4 Element#4—Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: • Silt Fence (BMP C233) • Straw Wattles(BMP C235) Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the 6 Blue Heron Resort- Stormwater Pollution Prevention Plan NPDES Construction Stormwater permit(as provided in Appendix D),the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed,to minimize tracking of sediments on vehicle tires away from the site and to minimize washoffof sediments from adjacent streets in runoff. Whenever possible, sediment laden water shall be discharged into onsite,relatively level, vegetated areas (BMP C240 paragraph 5,page 4-102). In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs(e.g., infiltration swales,ponds,trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however,those BMPs designed to remove solids by settling(wet ponds or detention ponds)can be used during the construction phase. When permanent stormwater BMPs will be used to control sediment discharge during construction,the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements once the remainder of the site has been stabilized. The following BMPs will be implemented as end-of-pipe sediment controls as required to meet permitted turbidity limits in the site discharge(s). Prior to the implementation of these technologies, sediment sources and erosion control and soil stabilization BMP efforts will be maximized to reduce the need for end-of-pipe sedimentation controls. ■ Temporary Sediment Pond(BMP C241) ■ Construction Stormwater Filtration(BMP C251) ■ Construction Stormwater Chemical Treatment(BMP C 250) (implemented only with prior written approval from Ecology). 3.1.5 Element 45— Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: • Temporary and Permanent Seeding(BMP C120) 7 Blue Heron Resort- Stormwater Pollution Prevention Plan • Mulching (BMP C 121) • Nets and Blankets(BMP C122) • Plastic Covering(BMP C123) • Topsoiling (BMP C 125) All disturbed areas shall be topsoiled, hydroseeded, mulched, or covered with erosion control blankets as soon as practicable. Plastic covering and temporary seeding shall be used for stockpiled soil during construction as needed during all construction phases. Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D),the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such,no soils shall remain exposed and unworked for more than 7 days during the dry season(May 1 to September 30) and 2 days during the wet season(October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets,waterways, and drainage channels. 3.1.6 Element#6—Protect Slopes All cut and fill slopes will be designed, constructed,and protected in a manner than minimizes erosion. The following specific BMPs will be used to protect slopes for this project: • Temporary and Permanent Seeding(BMP C 120) • Channel Lining (BMP C202) • Check Dams(BMP C207) 8 Blue Heron Resort- Stormwater Pollution Prevention Plan I • Straw Wattles (BMP C235) All disturbed areas shall be hydroseeded,mulched, or covered with erosion control blankets as soon as practicable. Straw wattles and check dams shall be implemented as required. Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D),the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 Element#7—Protect Drain Inlets All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate from entering storm drains until treatment can be provided. Storm Drain Inlet Protection(BMP C220)will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. The following inlet protection measures will be applied on this project: ■ Storm Drain Inlet Protection(BMP C220) If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D), or if no BMPs are listed above but deemed necessary during construction,the Certified Erosion and Sediment Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element#8—Stabilize Channels and Outlets Where site runoff is to be conveyed in channels,or discharged to a stream or some other natural drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: • Channel Lining(BMP C202) • Check Dams (BMP C207) 9 Blue Heron Resort- Stormwater Pollution Prevention Plan • Outlet Protection(BMP C209) • Straw Wattles(BMP C235) Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s)of the NPDES Construction Stormwater permit (as provided in Appendix D),the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, all temporary on-site conveyance channels shall be designed, constructed, and stabilized to prevent erosion from the expected peak 10 minute velocity of flow from a Type 1 A, 10-year, 24-hour recurrence interval storm for the developed condition. Alternatively,the 10-year, 1-hour peak flow rate indicated by an approved continuous runoff simulation model, increased by a factor of 1.6, shall be used. Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent streambanks, slopes, and downstream reaches shall be provided at the outlets of all conveyance systems. 3.1.9 Element#9—Control Pollutants All pollutants, including waste materials and demolition debris,that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well organized, and free of debris. If required,BMPs to be implemented to control specific sources of pollutants are discussed below. Vehicles, construction equipment, and/or petroleum product storage/dispensing: ■ All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills,and to identify maintenance needs to prevent leaks or spills. ■ On-site fueling tanks and petroleum product storage containers shall include secondary containment. ■ Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. ■ In order to perform emergency repairs on site,temporary plastic will be placed beneath and, if raining, over the vehicle. 10 Blue Heron Resort- Stormwater Pollution Prevention Plan ■ Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Excavation and tunneling spoils dewatering waste: ■ Dewatering BMPs and BMPs specific to the excavation and tunneling (including handling of contaminated soils) are discussed under Element 10. Demolition: ■ Dust released from demolished sidewalks,buildings, or structures will be controlled using Dust Control measures(BMP C140). ■ Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C 152). Concrete: ■ Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures(BMP C 151). Other: ■ Other BMPs will be administered as necessary to address any additional pollutant sources on site. �I This project does not require a Spill Prevention, Control,and Countermeasure (SPCC)Plan under the Federal regulations of the Clean Water Act(CWA). 3.1.10 Element#10—Control Dewatering All dewatering water from open cut excavation,tunneling, foundation work,trench, or underground vaults shall be discharged into a controlled conveyance system prior to discharge to a sediment trap or sediment pond. Channels will be stabilized,per Element#8. Clean,non- turbid dewatering water will not be routed through stormwater sediment ponds, and will be discharged to systems tributary to the receiving waters of the State in a manner that does not cause erosion, flooding, or a violation of State water quality standards in the receiving water. Highly turbid dewatering water from soils known or suspected to be contaminated, or from use of construction equipment,will require additional monitoring and treatment as required for the 11 Blue Heron Resort- Stormwater Pollution Prevention Plan specific pollutants based on the receiving waters into which the discharge is occurring. Such monitoring is the responsibility of the contractor. However,the dewatering of soils known to be free of contamination will trigger BMPs to trap sediment and reduce turbidity. At a minimum, geotextile fabric socks/bags/cells will be used to filter this material. Other BMPs to be used for sediment trapping and turbidity reduction include the following: ■ Use of a sedimentation bag, with outfall to Swale for small volumes of localized dewatering. ■ Infiltration 3.1.11 Element#11 —Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications(attached). Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive, and is temporarily stabilized,the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element#12—Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: ■ Design the project to fit the existing topography, soils, and drainage patterns. ■ Emphasize erosion control rather than sediment control. ■ Minimize the extent and duration of the area exposed. ■ Keep runoff velocities low. ■ Retain sediment on site. 12 Blue Heron Resort- Stormwater Pollution Prevention Plan ■ Thoroughly monitor site and maintain all ESC measures. ■ Schedule major earthwork during the dry season. In addition,project management will incorporate the key components listed below: As this project site is located west of the Cascade Mountain Crest,the project will be managed according to the following key project components: Phasing of Construction ■ The construction project is being phased to the extent practicable in order to prevent soil erosion, and,to the maximum extent possible,the transport of sediment from the site during construction. ■ Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). Seasonal Work Limitations ■ From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt-laden runoff will be prevented from leaving the site through a combination of the following: ❑ Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and ❑ Limitations on activities and the extent of disturbed areas; and ❑ Proposed erosion and sediment control measures. ■ Based on the information provided and/or local weather conditions,the local permitting authority may expand or restrict the seasonal limitation on site disturbance. ■ The following activities are exempt from the seasonal clearing and grading limitations: ❑ Routine maintenance and necessary repair of erosion and sediment control BMPs; 13 Blue Heron Resort- Stormwater Pollution Prevention Plan ❑ Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and ❑ Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions ■ Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. Inspection and Monitoring ■ All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: ❑ Assess the site conditions and construction activities that could impact the quality of stormwater, and ❑ Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. ■ A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times. ■ Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP ■ This SWPPP shall be retained on-site or within reasonable access to the site. ■ The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. 14 Blue Heron Resort- Stormwater Pollution Prevention Plan ■ The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven(7) days following the inspection. Alternate dewatering control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit(as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.2 Site Specific BMPs Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site specific plan sheets will be updated annually. 3.3 Additional Advanced BMPs • Construction Stormwater Chemical Treatment(BMP C250) • Construction Stormwater Filtration(BMP C251) 15 Blue Heron Resort- Stormwater Pollution Prevention Plan 4.0 Construction Phasing and BMP Implementation The BMP implementation schedule is driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. The BMP implementation schedule listed below is keyed to proposed phases of the construction project, and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such,the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October 1 to April 30. ■ Estimate of Construction start date: XX/XX/2010 ■ Estimate of Construction finish date: XX/XX/2010 ■ Mobilize equipment on site: XX/XX/2010 ■ Mobilize and store all ESC and soil stabilization products (store materials on hand BMP C150): XX/XX/2010 ■ Install ESC measures: ONGOING ■ Install stabilized construction entrance: XX/XX/2010 ■ Begin clearing and grubbing: XX/XX/2010 ■ Soil stabilization on excavated sideslopes (in idle, no work areas as shown on ESC plans) ONGOING ■ Temporary erosion control measures (hydroseeding) XX/XX/2010 ■ Site inspections reduced to monthly: XX/XX/2010 ■ Begin concrete pour and implement BMP C 151: XX/XX/2010 ■ Begin implementing soil stabilization and sediment control BMPs throughout the site in preparation for wet season: 09 / 24/2010 ■ Wet Season starts: 10 /01 /2010 16 Blue Heron Resort- Stormwater Pollution Prevention Plan ■ Site inspections and monitoring conducted weekly and for applicable rain events as detailed in Section 6 of this SWPPP: 10 / 01 / 2010 ■ Implement Element#1213MPs and manage site to minimize soil disturbance during the wet season 10 /01 /2010 ■ No site work such as grading or excavation planned: ■ Dry Season starts: 05/01 /2010 ■ Trenching begins: XX/XX/2010 ■ Excavate and install new utilities: XX/XX/2010 ■ Trenching ends: XX/XX/2010 ■ Final landscaping and planting begins: XX/XX/2010 ■ Permanent erosion control measures(hydroseeding): XX/XX/2010 i �i i i i i i i i i i 17 Blue Heron Resort- Stormwater Pollution Prevention Plan 5.0 Pollution Prevention Team 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: ■ Certified Erosion and Sediment Control Lead(CESCL)—primary contractor contact,responsible for site inspections(BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. ■ Resident Engineer—For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the projects supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative ■ Emergency Ecology Contact—individual to be contacted at Ecology in case of emergency. ■ Emergency Owner Contact—individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. ■ Non-Emergency Ecology Contact—individual that is the site owner or representative of the site owner that can be contacted if required. ■ Monitoring Personnel—personnel responsible for conducting water quality monitoring;for most sites this person is also the Certified Erosion and Sediment Control Lead. 18 Blue Heron Resort- Stormwater Pollution Prevention Plan 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Phone Number Certified Erosion and Sediment Control Lead(CESCL) T.B.D. T.B.D. Resident Engineer J.W.Morrissette&Associates Inc.,P.S. (360)352-9456 Emergency Ecology Contact T.B.D. T.B.D. Emergency Owner Contact T.B.D. T.B.D. Non-Emergency Ecology Contact T.B.D. T.B.D. Monitoring Personnel T.B.D. T.B.D. 19 Blue Heron Resort- Stormwater Pollution Prevention Plan 6.0 Site Inspections and Monitoring Monitoring includes visual inspection,monitoring for water quality parameters of concern, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; ■ Site inspections; and, ■ Stormwater quality monitoring. For convenience,the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated,the site log book but must be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected,maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL per BMP C160. The name and contact information for the CESCL is provided in ) Section 5 of this SWPPP. Site inspection will occur in all areas disturbed by construction activities and at all stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For sites with temporary stabilization measures,the site inspection frequency can be reduced to once every month. 20 1 Blue Heron Resort- Stormwater Pollution Prevention Plan 6.1.2 Site Inspection Documentation The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document,but will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.2 Stormwater Quality Monitoring Refer to permit section S4.G for sampling procedures and guidance. 6.2.1 Turbidity Sampling Monitoring requirements for the proposed project will include either turbidity or water transparency sampling to monitor site discharges for water quality compliance with the 2005 Construction Stormwater General Permit(Appendix D). Sampling will be conducted at all discharge points at least once per calendar week. Turbidity or transparency monitoring will follow the analytical methodologies described in Section S4 of the 2005 Construction Stormwater General Permit(Appendix D). The key benchmark values that require action are 25 NTU for turbidity (equivalent to 32 cm transparency)and 250 NTU for turbidity (equivalent to 6 cm transparency). If the 25 NTU benchmark for turbidity (equivalent to 32 cm transparency) is exceeded,the following steps will be conducted: 1. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document revisions to the SWPPP as necessary. 3. Sample discharge location daily until the analysis results are less than 25 NTU (turbidity) or greater than 32 cm(transparency). If the turbidity is greater than 25 NTU (or transparency is less than 32 cm)but less than 250 NTU (transparency greater than 6 cm) for more than 3 days, additional treatment BMPs will be implemented within 24 hours of the third consecutive sample that exceeded the benchmark value. Additional treatment BMPs to be considered will include, but are not limited to, off-site treatment, infiltration, filtration and chemical treatment. If the 250 NTU benchmark for turbidity (or less than 6 cm transparency) is exceeded at any time, the following steps will be conducted: 21 Blue Heron Resort- Stormwater Pollution Prevention Plan 1. Notify Ecology by phone within 24 hours of analysis(see Section 5.0 of this SWPPP for contact information). 2. Continue daily sampling until the turbidity is less than 25 NTU (or transparency is greater than 32 cm). 3. Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration and chemical treatment within 24 hours of the first 250 NTU exceedance. 4. Implement additional treatment BMPs as soon as possible,but within 7 days of the first 250 NTU exceedance. 5. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Sampling Stormwater runoff will be monitored for pH starting on the first day of any activity that includes more than 40 yards of poured or recycled concrete, or after the application of"Engineered Soils" such as, Portland cement treated base, cement kiln dust, or fly ash. This does not include fertilizers. For concrete work,pH monitoring will start the first day concrete is poured and continue until 3 weeks after the last pour. For engineered soils,the pH monitoring period begins when engineered soils are first exposed to precipitation and continue until the area is fully stabilized. Stormwater samples will be collected daily from all points of discharge from the site and measured for pH using a calibrated pH meter,pH test kit, or wide range pH indicator paper. If the measured pH is 8.5 or greater,the following steps will be conducted: 1. Prevent the high pH water from entering storm drains or surface water. 2. Adjust or neutralize the high pH water if necessary using appropriate technology such as CO2 sparging (liquid or dry ice). 3. Contact Ecology if chemical treatment other than CO2 sparging is planned. 22 Blue Heron Resort- Stormwater Pollution Prevention Plan 7.0 Reporting and Recordkeeping 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; ■ Site inspections; and, ■ Stormwater quality monitoring. For convenience,the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. The site log book is attached to this SWPPP and shall be maintained as a part of this SWPPP. 7.1.2 Records Retention Records of all monitoring information(site log book, inspection reports/checklists, etc.),this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimum of three years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit,Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 7.1.4 Updating the SWPPP P g In accordance with Conditions S3, S4.B, and S9.13.3 of the General Permit,this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in 23 Blue Heron Resort- Stormwater Pollution Prevention Plan stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s)that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. 7.2 Reporting 7.2.1 Discharge Monitoring Reports If cumulative soil disturbance is 5 acres or larger: Discharge Monitoring Reports (DMRs)will be submitted to Ecology monthly. Of there was no discharge during a given monitoring period,the Permittee shall submit the form as required,with the words"No discharge"entered in the place of monitoring results. The DMR due date is 15 days following the end of each month. 7.2.2 Notification of Noncompliance If any of the terms and conditions of the permit are not met, and it causes a threat to human health or the environment,the following steps will be taken in accordance with permit section SS.F: 1. Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five(5)days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted P g p to Ecology within five (5) days, unless requested earlier by Ecology. Any time turbidity sampling indicates turbidity is 250 nephelometric turbidity units (NTU) or greater or water transparency is 6 centimeters or less,the Ecology regional office will be notified by phone within 24 hours of analysis as required by permit condition SS.A(see Section 5.0 of this SWPPP for contact information). In accordance with permit condition S4.F.6.b,the Ecology regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water(see Section 5.0 of this SWPPP for contact information). 24 Blue Heron Resort- Stormwater Pollution Prevention Plan 7.2.3 Permit Application and Changes In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction (if applicable)to be covered by the General Permit. 25 Blue Heron Resort- Stormwater Pollution Prevention Plan Appendix A — Site Plans See Appendix 6 of Drainage Report 26 Blue Heron Resort- Stormwater Pollution Prevention Plan Appendix B — Construction BMPs Stabilized Construction Entrance(BMP C105) Temporary and Permanent Seeding(BMP C120) Mulching (BMP C121) Nets and Blankets (BMP C122) Plastic Covering(BMP C123) Topsoiling (BMP C125) Dust Control (BMP C 140) Concrete Handling (BMP C 151) Sawcutting and Surfacing Pollution Prevention (BMP C 152) Certified Erosion and Sediment Control Lead(BMP C160) Scheduling (BMP C 162) Channel Lining (BMP C202) Check Dams (BMP C207) Outlet Protection(BMP C209) Storm Drain Inlet Protection (BMP C220) Silt Fence (BMP C233) Straw Wattles (BMP C235) 27 BMP C105: Stabilized Construction Entrance Purpose Construction entrances are stabilized to reduce the amount of sediment transported onto paved roads by vehicles or equipment by constructing a stabilized pad of quarry spalls at entrances to construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be leaving a construction site and traveling on paved roads or other paved areas within 1,000 feet of the site. On large commercial,highway, and road projects,the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. Design and • See Figure 4.2 for details.Note: the 100' minimum length of the Installation entrance shall be reduced to the maximum practicable size when the Specifications size or configuration of the site does not allow the full length(100'). • A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the following standards: Grab Tensile Strength (ASTM D4751) 200 psi min. Grab Tensile Elongation (ASTM D4632) 30% max. Mullen Burst Strength (ASTM D3786-80a) 400 psi min. AOS (ASTM D4751) 1 20-45(U.S. standard sieve size) • Consider early installation of the first lift of asphalt in areas that will paved; this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large concrete pours, excess concrete is often available for this purpose. • Hog fuel(wood-based mulch)may be substituted for or combined with quarry spalls in areas that will not be used for permanent roads. Hog fuel is generally less effective at stabilizing construction entrances and should be used only at sites where the amount of traffic is very limited. Hog fuel is not recommended for entrance stabilization in urban areas. The effectiveness of hog fuel is highly variable and it generally requires more maintenance than quarry spalls. The inspector may at any time require the use of quarry spalls if the hog fuel is not preventing sediment from being tracked onto pavement or if the hog fuel is being carried onto pavement. Hog fuel is prohibited in permanent roadbeds because organics in the subgrade soils cause degradation of the subgrade support over time. • Fencing(see BMPs C 103 and C 104) shall be installed as necessary to restrict traffic to the construction entrance. 4-8 Volume 11- Construction Stormwater Pollution Prevention February 2005 • Whenever possible,the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. Maintenance . Quarry spalls(or hog fuel)shall be added if the pad is no longer in Standards accordance with the specifications. • If the entrance is not preventing sediment from being tracked onto pavement,then alternative measures to keep the streets free of sediment shall be used. This may include street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. • Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets,the construction of a small sump shall be considered. The sediment would then be washed into the sump where it can be controlled. • Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. • If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing (see BMPs C103 and C104) shall be installed to control traffic. • Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be ermanently stabilized. Driveway shal meet the requirements of the permitting agency H is recommended that the entrance be crowned so that runoff Poad drains off the pad r i Install driveway culvert If there is a ditch present 4'-B"quarry spalls roadsideGeotextile— 12'min.thickness �5 J Provide full width of ingress egress area Figure 4.2— Stabilized Construction Entrance February 2005 Volume ll— Construction Stormwater Pollution Prevention 4-9 BMP C120: Temporary and Permanent Seeding Purpose Seeding is intended to reduce erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion. Conditions of Use ' Seeding may be used throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. Channels that will be vegetated should be installed before major earthwork and hydroseeded with a Bonded Fiber Matrix. The vegetation should be well established(i.e., 75 percent cover)before water is allowed to flow in the ditch. With channels that will have high flows,erosion control blankets should be installed over the hydroseed. If vegetation cannot be established from seed before water is allowed in the ditch, sod should be installed in the bottom of the ditch over hydromulch and blankets. • Retention/detention ponds should be seeded as required. • Mulch is required at all times because it protects seeds from heat, moisture loss, and transport due to runoff. • All disturbed areas shall be reviewed in late August to early September and all seeding should be completed by the end of September. Otherwise,vegetation will not establish itself enough to provide more than average protection. • At final site stabilization, all disturbed areas not otherwise vegetated or stabilized shall be seeded and mulched. Final stabilization means the completion of all soil disturbing activities at the site and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures(such as pavement, riprap, gabions or geotextiles)which will prevent erosion. Design and • Seeding should be done during those seasons most conducive to Installation growth and will vary with the climate conditions of the region. Specifications Local experience should be used to determine the appropriate seeding periods. The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1. Seeding that occurs between July 1 and August 30 will require irrigation until 75 percent grass cover is established. Seeding that occurs between October 1 and March 30 will require a mulch or plastic cover until 75 percent grass cover is established. To prevent seed from being washed away, confirm that all required surface water control measures have been installed. February 2005 Volume 11- Construction Stormwater Pollution Prevention 4-13 • The seedbed should be firm and rough. All soil should be roughened no matter what the slope. If compaction is required for engineering purposes, slopes must be track walked before seeding. Backblading or smoothing of slopes greater than 4:1 is not allowed if they are to be seeded. • New and more effective restoration-based landscape practices rely on deeper incorporation than that provided by a simple single-pass rototilling treatment. Wherever practical the subgrade should be initially ripped to improve long-term permeability, infiltration,and water inflow qualities. At a minimum,permanent areas shall use soil amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches the rototilling process should be done in multiple lifts, or the prepared soil system shall be prepared properly and then placed to achieve the specified depth. • Organic matter is the most appropriate form of"fertilizer"because it provides nutrients (including nitrogen,phosphorus, and potassium) in the least water-soluble form. A natural system typically releases 2-10 percent of its nutrients annually. Chemical fertilizers have since been formulated to simulate what organic matter does naturally. • In general, 10-4-6 N-P-K(nitrogen-phosphorus-potassium) fertilizer can be used at a rate of 90 pounds per acre. Slow-release fertilizers should always be used because they are more efficient and have fewer environmental impacts. It is recommended that areas being seeded for final landscaping conduct soil tests to determine the exact type and quantity of fertilizer needed. This will prevent the over-application of fertilizer. Fertilizer should not be added to the hydromulch machine and agitated more than 20 minutes before it is to be used. If agitated too much, the slow-release coating is destroyed. • There are numerous products available on the market that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be necessary. Cottonseed meal is a good source of long-term, slow-release, available nitrogen. • Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 percent tackifier. Mulch may be made up of 100 percent: cottonseed meal; fibers made of wood,recycled cellulose, hemp, and kenaf; compost; or blends of these. Tackifier shall be plant- based, such as guar or alpha plantago, or chemical-based such as polyacrylamide or polymers. Any mulch or tackifier product used shall be installed per manufacturer's instructions. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. 4-14 Volume 11— Construction Stormwater Pollution Prevention February 2005 • Mulch is always required for seeding. Mulch can be applied on top of the seed or simultaneously by hydroseeding. • On steep slopes, Bonded Fiber Matrix (BFM)or Mechanically Bonded Fiber Matrix (MBFM)products should be used. BFM/MBFM products are applied at a minimum rate of 3,000 pounds per acre of mulch with approximately 10 percent tackifier. Application is made so that a minimum of 95 percent soil coverage is achieved. Numerous products are available commercially and should be installed per manufacturer's instructions. Most products require 24-36 hours to cure before a rainfall and cannot be installed on wet or saturated soils. Generally,these products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer. BFMs and MBFMs have some advantages over blankets: • No surface preparation required; • Can be installed via helicopter in remote areas; • On slopes steeper than 2.5:1, blanket installers may need to be roped and harnessed for safety; • They are at least$1,000 per acre cheaper installed. In most cases, the shear strength of blankets is not a factor when used on slopes, only when used in channels. BFMs and MBFMs are good alternatives to blankets in most situations where vegetation establishment is the goal. • When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. One way to overcome this is to increase seed quantities by up to 50 percent. • Vegetation establishment can also be enhanced by dividing the hydromulch operation into two phases: 1. Phase 1-Install all seed and fertilizer with 2 5-3 0 percent mulch and tackifier onto soil in the first lift; 2. Phase 2-Install the rest of the mulch and tackifier over the first lift. An alternative is to install the mulch, seed, fertilizer, and tackifier in one lift. Then, spread or blow straw over the top of the hydromulch at a rate of about 800-1000 pounds per acre. Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: 1. Irrigation 2. Reapplication of mulch 3. Repair of failed slope surfaces February2 - Prevention 4-15 005 Volume 11 Construction Stormwater Pollution Prevent o This technique works with standard hydromulch(1,500 pounds per acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum). • Areas to be permanently landscaped shall provide a healthy topsoil that reduces the need for fertilizers, improves overall topsoil quality, provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. This can be accomplished in a number of ways: Recent research has shown that the best method to improve till soils is to amend these soils with compost. The optimum mixture is approximately two parts soil to one part compost. This equates to 4 inches of compost mixed to a depth of 12 inches in till soils. Increasing the concentration of compost beyond this level can have negative effects on vegetal health, while decreasing the concentrations can reduce the benefits of amended soils. Please note: The compost should meet specifications for Grade A quality compost in Ecology Publication 94-038. Other soils, such as gravel or cobble outwash soils,may require different approaches. Organics and fines easily migrate through the loose structure of these soils. Therefore,the importation of at least 6 inches of quality topsoil, underlain by some type of filter fabric to prevent the migration of fines, may be more appropriate for these soils. Areas that already have good topsoil, such as undisturbed areas, do not require soil amendments. • Areas that will be seeded only and not landscaped may need compost or meal-based mulch included in the hydroseed in order to establish vegetation. Native topsoil should be re-installed on the disturbed soil surface before application. • Seed that is installed as a temporary measure may be installed by hand if it will be covered by straw, mulch, or topsoil. Seed that is installed as a permanent measure may be installed by hand on small areas (usually less than 1 acre)that will be covered with mulch,topsoil, or erosion blankets. The seed mixes listed below include recommended mixes for both temporary and permanent seeding. These mixes, with the exception of the wetland mix, shall be applied at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow- release fertilizers are used. Local suppliers or the local conservation district should be consulted for their recommendations because the appropriate mix depends on a variety of factors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used. 4-16 Volume 11— Construction Stormwater Pollution Prevention February 2005 Table 4.1 represents the standard mix for those areas where just a temporary vegetative cover is required. Table 4.1 Temporary Erosion Control Seed Mix %Wei ht % Purity % Germination Chewings or annual blue grass 40 98 90 Festuca rubra var. commutata or Poa anna Perennial rye- 50 98 90 Lolium perenne _ Redtop or colonial bentgrass 5 92 85 Agrostis alba or Agrostis tenuis White dutch clover 5 98 90 Trifolium re ens Table 4.2 provides just one recommended possibility for landscaping seed. Table 4.2 Landscaping Seed Mix %Wei ht %Puri %Germination Perennial rye blend 70 98 90 Lolium perenne Chewings and red fescue blend 30 98 90 Festuca rubra var.commutata or Festuca rubra This turf seed mix in Table 4.3 is for dry situations where there is no need for much water. The advantage is that this mix requires very little maintenance. Table 4.3 Low-Growing Turf Seed Mix % weight % Purity % Germination Dwarf tall fescue(several varieties) 45 98 90 Festuca arundinacea var. Dwarf perennial rye(Barclay) 30 98 90 Lolium perenne var. barclay Red fescue 20 98 90 Festuca rubra Colonial bentgrass 5 98 90 Agrostis tenuis Table 4.4 presents a mix recommended for bioswales and other intermittently wet areas. Table 4.4 Bioswale Seed Mix* %Wei ht %Purity % Germination Tall or meadow fescue 75-80 98 90 Festuca arundinacea or Festuca elatior Seaside/Creeping bentgrass 10-15 92 85 Agrostis palustris Redtop bentgrass 5-10 90 80 Agrostis alba or Agrostis gigantea *Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-17 The seed mix shown in Table 4.5 is a recommended low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands. Other mixes may be appropriate, depending on the soil type and hydrology of the area. Recent research suggests that bentgrass (agrostis sp.) should be emphasized in wet-area seed mixes. Apply this mixture at a rate of 60 pounds per acre. Table 4.5 Wet Area Seed Mix* %Weight % Purit %Germination Tall or meadow fescue 60-70 98 90 Festuca arundinacea or Festuca elatior Seaside/Creeping bentgrass 10-15 98 85 Agrostis palustris Meadow foxtail 10-15 90 80 Ale ocurus pratensis Alsike clover 1-6 98 90 Tri olium h bridum Redtop bentgrass 1-6 92 85 Agrostis alba *Modified Briargreen,Inc. Hydroseeding Guide Wetlands Seed Mix The meadow seed mix in Table 4.6 is recommended for areas that will be maintained infrequently or not at all and where colonization by native plants is desirable. Likely applications include rural road and utility right- of-way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months. The appropriateness of clover in the mix may need to be considered, as this can be a fairly invasive species. If the soil is amended,the addition of clover may not be necessary. Table 4.6 Meadow Seed Mix %Wei ht %Puri % Germination Redtop or Oregon bentgrass 20 92 85 Agrostis alba or Agrostis ore onensis Red fescue 70 98 90 Festuca rurra White dutch clover 10 98 90 Tri olium re ens Maintenance • Any seeded areas that fail to establish at least 80 percent cover(100 Standards percent cover for areas that receive sheet or concentrated flows) shall be reseeded. If reseeding is ineffective, an alternate method, such as sodding,mulching, or nets/blankets, shall be used. If winter weather prevents adequate grass growth,this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. 4-18 Volume 11— Construction Stormwater Pollution Prevention February 2005 • After adequate cover is achieved,any areas that experience erosion shall be reseeded and protected by mulch. If the erosion problem is drainage related,the problem shall be fixed and the eroded area reseeded and protected by mulch. • Seeded areas shall be supplied with adequate moisture, but not watered to the extent that it causes runoff. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-19 BMP C121: Mulching Purpose The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture,holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There is an enormous variety of mulches that can be used. Only the most common types are discussed in this section. Conditions of Use As a temporary cover measure,mulch should be used: • On disturbed areas that require cover measures for less than 30 days. • As a cover for seed during the wet season and during the hot summer months. • During the wet season on slopes steeper than 3H:1 V with more than 10 feet of vertical relief. • Mulch may be applied at any time of the year and must be refreshed periodically. Design and For mulch materials, application rates, and specifications, see Table 4.7. Installation Note: Thicknesses may be increased for disturbed areas in or near Specifications sensitive areas or other areas highly susceptible to erosion. Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities(densities)than straw, wood, or chipped material. Maintenance • The thickness of the cover must be maintained. Standards • Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related,then the problem shall be fixed and the eroded area remulched. I I 4-20 Volume 11— Construction Stormwater Pollution Prevention February 2005 �I Table 4.7 Mulch Standards and Guidelines Mulch Application Material Quality Standards Rates Remarks Straw Air-dried;free from 2"-3"thick;5 Cost-effective protection when applied with adequate undesirable seed and bales per 1000 sf thickness. Hand-application generally requires greater coarse material. or 2-3 tons per thickness than blown straw.The thickness of straw may be acre reduced by half when used in conjunction with seeding. In windy areas straw must be held in place by crimping,using a tackifier,or covering with netting. Blown straw always has to be held in place with a tackifier as even light winds will blow it away.Straw,however,has several deficiencies that should be considered when selecting mulch materials.It often introduces and/or encourages the propagation of weed species and it has no significant long-term benefits. Straw should be used only if mulches with long-term benefits are unavailable locally. It should also not be used within the ordinary high-water elevation of surface waters(due to flotation). Hydromulch No growth Approx.25-30 Shall be applied with hydromulcher. Shall not be used inhibiting factors. lbs per 1000 sf without seed and tackifier unless the application rate is at or 1500 -2000 least doubled. Fibers longer than about%-1 inch clog lbs per acre hydromulch equipment. Fibers should be kept to less than% inch. Composted No visible water or 2"thick min.; More effective control can be obtained by increasing Mulch and dust during approx. 100 tons thickness to 3". Excellent mulch for protecting final grades Compost handling. Must be per acre(approx. until landscaping because it can be directly seeded or tilled purchased from 800 lbs per yard) into soil as an amendment. Composted mulch has a coarser supplier with Solid size gradation than compost.It is more stable and practical Waste Handling to use in wet areas and during rainy weather conditions. Permit(unless exempt). Chipped Site Average size shall 2"minimum This is a cost-effective way to dispose of debris from Vegetation be several inches. thickness clearing and grubbing,and it eliminates the problems Gradations from associated with burning. Generally,it should not be used on fines to 6 inches in slopes above approx. 10%because of its tendency to be length for texture, transported by runoff. It is not recommended within 200 variation,and feet of surface waters. If seeding is expected shortly after interlocking mulch,the decomposition of the chipped vegetation may tie properties. up nutrients important to grass establishment. Wood-based No visible water or 2"thick;approx. This material is often called"hog or hogged fuel." It is Mulch dust during 100 tons per acre usable as a material for Stabilized Construction Entrances handling. Must be (approx.800 lbs. (BMP C105)and as a mulch. The use of mulch ultimately purchased from a per cubic yard) improves the organic matter in the soil. Special caution is supplier with a Solid advised regarding the source and composition of wood- Waste Handling based mulches. Its preparation typically does not provide Permit or one any weed seed control,so evidence of residual vegetation in exempt from solid its composition or known inclusion of weed plants or seeds waste regulations. should be monitored and prevented(or minimized). February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-21 BMP C122: Nets and Blankets Pui pose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets(commonly called matting)are strands of material woven into an open, but high-tensile strength net(for example, coconut fiber matting). Blankets are strands of material that are not tightly woven,but instead form a layer of interlocking fibers,typically held together by a biodegradable or photodegradable netting(for example, excelsior or straw blankets). They generally have lower tensile strength than nets,but cover the ground more completely. Coir(coconut fiber)fabric comes as both nets and blankets. Conditions of Use Erosion control nets and blankets should be used: • To aid permanent vegetated stabilization of slopes 211:1 V or greater and with more than 10 feet of vertical relief. • For drainage ditches and swales(highly recommended). The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open,porous structure. Synthetic nets and blankets can be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. 100 percent synthetic blankets manufactured for use in ditches may be easily reused as temporary ditch liners. Disadvantages of blankets include: • Surface preparation required; • On slopes steeper than 2.5:1, blanket installers may need to be roped and harnessed for safety; • They cost at least$4,000-6,000 per acre installed. Advantages of blankets include: • Can be installed without mobilizing special equipment; • Can be installed by anyone with minimal training; • Can be installed in stages or phases as the project progresses; • Seed and fertilizer can be hand-placed by the installers as they progress down the slope; • Can be installed in any weather; • There are numerous types of blankets that can be designed with various parameters in mind. Those parameters include: fiber blend, mesh strength, longevity,biodegradability, cost, and availability. 4-22 Volume 11— Construction Stormwater Pollution Prevention February 2005 Design and • See Figure 4.4 and Figure 4.5 for typical orientation and installation of Installation blankets used in channels and as slope protection.Note: these are Specifications typical only; all blankets must be installed per manufacturer's installation instructions. • Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. • Installation of Blankets on Slopes: l. Complete final grade and track walk up and down the slope. 2. Install hydromulch with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the blanket into the small trench and staple approximately every 18 inches. NOTE: Staples are metal,"U"-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5. Roll the blanket slowly down the slope as installer walks backwards. NOTE: The blanket rests against the installer's legs. Staples are installed as the blanket is unrolled. It is critical that the proper staple pattern is used for the blanket being installed. The blanket is not to be allowed to roll down the slope on its own as this stretches the blanket making it impossible to maintain soil contact. In addition, no one is allowed to walk on the blanket after it is in place. 6. If the blanket is not long enough to cover the entire slope length, the trailing edge of the upper blanket should overlap the leading edge of the lower blanket and be stapled. On steeper slopes,this overlap should be installed in a small trench, stapled, and covered with soil. • With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engineer consults the manufacturer's information and that a site visit takes place in order to insure that the product specified is appropriate. Information is also available at the following web sites: 1. WSDOT: hM://www.wsdot.wa.gov/eesc/environmental/ 2. Texas Transportation Institute: http://www.dot.state.tx.us/insdtdot/orgchart/cmd/erosion/contents. htm February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-23 • Jute matting must be used in conjunction with mulch(BMP C121). Excelsior,woven straw blankets and coir(coconut fiber)blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. • In general,most nets (e.g.,jute matting)require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. • Extremely steep,unstable,wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks, beaches and other high-energy environments. If synthetic blankets are used,the soil should be hydromulched first. • 100 percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. • Most netting used with blankets is photodegradable,meaning they break down under sunlight(not UV stabilized). However,this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non-degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. Maintenance • Good contact with the ground must be maintained, and erosion must Standards not occur beneath the net or blanket. • Any areas of the net or blanket that are damaged or not in close contact with the ground shall be repaired and stapled. • If erosion occurs due to poorly controlled drainage,the problem shall be fixed and the eroded area protected. 4-24 Volume 11— Construction Stormwater Pollution Prevention February 2005 o 2'/ ' Longitudinal Anchor Trench Terminal Slope and Channel Anchor Trench i Stake at T-5' P (1-1.5m)intervals. P Check slot at 25'(7.6m)intervals �\ Isometric View r 6'(150—) Initial Channel Anchor Trench Intermittent Check Slot NOTES: 1.Check slots to be constructed per manufacturers specifications. 2.Staking or stapling layout per manufacturers specifications. Figure 4.4—Channel Installation Slope surface shall be smooth before placement for proper soil contact. If there is a berm at the Stapling pattern as per top of slope,anchor manufacturer's recommendations. upslope of the berm. _ Min.2" Overlap _ I I tI I Anchor in 6"x6"min.Trench and staple at 12" intervals. III—I' Min.6"overlap. aI—I III Staple overlaps III=1 I= I—i I I I—I I M I I—i1 max.5"spacing. —1l_I I I—lilt—tt—i Bring material down to a level area,turn Do not stretch blankets/mattings tight- the end under 4"and staple at 12"intervals. allow the rolls to mold to any irregularities. For slopes less than 3H:1 V,rolls Lime,fertilize,and seed before installation. may be placed in horizontal strips. Planting of shrubs,trees,etc.Should occur after installation. Figure 4.5— Slope Installation February 2005 Volume II— Construction Stormwater Pollution Prevention 4-25 BMP C123: Plastic Covering Purpose Plastic covering provides immediate,short-term erosion protection to slopes and disturbed areas. Conditions of • Plastic covering may be used on disturbed areas that require cover Use measures for less than 30 days, except as stated below. • Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term(greater than six months) applications. • Clear plastic sheeting can be used over newly-seeded areas to create a greenhouse effect and encourage grass growth if the hydroseed was installed too late in the season to establish 75 percent grass cover, or if the wet season started earlier than normal. Clear plastic should not be used for this purpose during the summer months because the resulting high temperatures can kill the grass. • Due to rapid runoff caused by plastic sheeting,this method shall not be used upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. • While plastic is inexpensive to purchase,the added cost of installation, maintenance,removal, and disposal make this an expensive material, up to $1.50-2.00 per square yard. • Whenever plastic is used to protect slopes,water collection measures must be installed at the base of the slope. These measures include plastic-covered berms, channels, and pipes used to covey clean rainwater away from bare soil and disturbed areas. At no time is clean runoff from a plastic covered slope to be mixed with dirty runoff from a project. • Other uses for plastic include: 1. Temporary ditch liner; 2. Pond liner in temporary sediment pond; 3. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored; 4. Emergency slope protection during heavy rains; and, 5. Temporary drainpipe ele hant trunk used to direct water. p az'Y ("elephant ) 4-26 Volume 11— Construction Stormwater Pollution Prevention February 2005 Design and Plastic slope cover must be installed as follows: Installation 1. Run plastic up and down slope,not across slope; Specifications 2. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet; 3. Minimum of 8-inch overlap at seams; 4. On long or wide slopes, or slopes subject to wind, all seams should be taped; 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath; 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and pound a wooden stake through each to hold them in place; 7. Inspect plastic for rips,tears, and open seams regularly and repair immediately. This prevents high velocity runoff from contacting bare soil which causes extreme erosion; 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. • Plastic sheeting shall have a minimum thickness of 0.06 millimeters. • If erosion at the toe of a slope is likely, a gravel berm,riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance • Torn sheets must be replaced and open seams repaired. Standards • If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and replaced. • When the plastic is no longer needed, it shall be completely removed. • Dispose of old tires appropriately. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-27 BMP C125: Topsoiling Purpose To provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself,topsoiling is an integral component of providing permanent cover in those areas where there is an unsuitable soil surface for plant growth. Native soils and disturbed soils that have been organically amended not only retain much more stormwater, but they also serve as effective biofilters for urban pollutants and, by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. Conditions of Native soils should be left undisturbed to the maximum extent Use practicable. Native soils disturbed during clearing and grading should be restored,to the maximum extent practicable,to a condition where moisture-holding capacity is equal to or better than the original site conditions. This criterion can be met by using on-site native topsoil, incorporating amendments into on-site soil, or importing blended topsoil. • Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH(high acid) levels. • Stripping of existing,properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. If an existing soil system is functioning properly it shall be preserved in its undisturbed and uncompacted condition. • Depending on where the topsoil comes from, or what vegetation was on site before disturbance, invasive plant seeds may be included and could cause problems for establishing native plants, landscaped areas, or grasses. • Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimum conditions for establishing grasses. Commercially available mycorrhiza products should be used when topsoil is brought in from off-site. Design and If topsoiling is to be done, the following items should be considered: Installation • Maximize the depth of the topsoil wherever possible to provide the Specifications maximum possible infiltration capacity and beneficial growth P p ty medium. Topsoil depth shall be at least 8 inches with a minimum organic content of 10 percent weight and H between 6.0 and 8.0 g P �'y g p or matchingthe H of the undisturbed soil. This can be accomplished p p ed either by returning native topsoil to the site and/or incorporating organic amendments. Organic amendments should be incorporated to g g � a minimum 8-inch depth except where tree roots or other natural February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-29 features limit the depth of incorporation. Subsoils below the 12-inch depth should be scarified at least 2 inches to avoid stratified layers, where feasible. The decision to either layer topsoil over a subgrade or incorporate topsoil into the underlying layer may vary depending on the planting specified. • If blended topsoil is imported, then fines should be limited to 25 percent passing through a 200 sieve. • The final composition and construction of the soil system will result in a natural selection or favoring of certain plant species over time. For example, recent practices have shown that incorporation of topsoil may favor grasses,while layering with mildly acidic, high-carbon amendments may favor more woody vegetation. • Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than one pile in proximity to areas where topsoil will be used. • Allow sufficient time in scheduling for topsoil to be spread prior to seeding, sodding, or planting. • Care must be taken not to apply to subsoil if the two soils have contrasting textures. Sandy topsoil over clayey subsoil is a particularly poor combination, as water creeps along the junction between the soil layers and causes the topsoil to slough. • If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method to prevent a lack of bonding is to actually work the topsoil into the layer below for a depth of at least 6 inches. • Ripping or re-structuring the subgrade may also provide additional benefits regarding the overall infiltration and interflow dynamics of the soil system. • Field exploration of the site shall be made to determine if there is surface soil of sufficient quantity and quality to justify stripping. Topsoil shall be friable and loamy (loam, sandy loam, silt loam, sandy clay loam, clay loam). Areas of natural ground water recharge should be avoided. • Stripping shall be confined to the immediate construction area. A 4-to 6- inch stripping depth is common,but depth may vary depending on the particular soil. All surface runoff control structures shall be in place prior to stripping. Stockpiling of topsoil shall occur in the following manner: • Side slopes of the stockpile shall not exceed 2:1. • An interceptor dike with gravel outlet and silt fence shall surround all topsoil stockpiles between October 1 and April 30. Between May 1 4-30 Volume 11— Construction Stormwater Pollution Prevention February 2005 and September 30,an interceptor dike with gravel outlet and silt fence shall be installed if the stockpile will remain in place for a longer period of time than active construction grading. • Erosion control seeding or covering with clear plastic or other mulching materials of stockpiles shall be completed within 2 days (October 1 through April 30) or 7 days(May 1 through September 30) of the formation of the stockpile. Native topsoil stockpiles shall not be covered with plastic. • Topsoil shall not be placed while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. • Previously established grades on the areas to be topsoiled shall be maintained according to the approved plan. • When native topsoil is to be stockpiled and reused the following should apply to ensure that the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: g Y 1. Topsoil is to be re-installed within 4 to 6 weeks; 2. Topsoil is not to become saturated with water; 3. Plastic cover is not allowed. II Maintenance Inspect stockpiles regularly, especially after large storm events. Standards Stabilize any areas that have eroded. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-31 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways,and surface waters. Conditions of Use • In areas (including roadways) subject to surface and air movement of dust where on-site and off-site impacts to roadways, drainage ways, or surface waters are likely. Desi,n and • Vegetate or mulch areas that will not receive vehicle traffic. In areas Installation where planting, mulching, or paving is impractical, apply gravel or Specifications landscaping rock. • Limit dust generation by clearing only those areas where immediate activity will take place, leaving the remaining area(s) in the original condition, if stable. Maintain the original ground cover as long as practical. • Construct natural or artificial windbreaks or windscreens. These may be designed as enclosures for small dust sources. • Sprinkle the site with water until surface is wet. Repeat as needed. To prevent carryout of mud onto street, refer to Stabilized Construction Entrance (BMP C105). • Irrigation water can be used for dust control. Irrigation systems should be installed as a first step on sites where dust control is a concern. • Spray exposed soil areas with a dust palliative, following the manufacturer's instructions and cautions regarding handling and application. Used oil is prohibited from use as a dust suppressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. • PAM(BMP C126) added to water at a rate of 0.5 lbs. per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone. This is due to the increased infiltration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily transported by wind. Adding PAM may actually reduce the quantity of water needed for dust control,especially in eastern Washington. Since the wholesale cost of PAM is about$ 4.00 per pound,this is an extremely cost- effective dust control method. Techniques that can be used for unpaved roads and lots include: • Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. • Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. 4-40 Volume 11— Construction Stormwater Pollution Prevention February 2005 • Add surface gravel to reduce the source of dust emission. Limit the amount of fine particles (those smaller than .075 min)to 10 to 20 percent. • Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstruction. • Encourage the use of alternate,paved routes, if available. • Restrict use by tracked vehicles and heavy trucks to prevent damage to road surface and base. • Apply chemical dust suppressants using the admix method,blending the product with the top few inches of surface material. Suppressants may also be applied as surface treatments. • Pave unpaved permanent roads and other trafficked areas. • Use vacuum street sweepers. • Remove mud and other dirt promptly so it does not dry and then turn into dust. • Limit dust-causing work on windy days. • Contact your local Air Pollution Control Authority for guidance and training on other dust control measures. Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. Maintenance Respray area as necessary to keep dust to a minimum. Standards February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-41 BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. This BMP is intended to minimize and eliminate concrete process water and slurry from entering waters of the state. Conditions of Use Any time concrete is used,these management practices shall be utilized. Concrete construction projects include, but are not limited to,the following: • Curbs • Sidewalks • Roads • Bridges • Foundations Floors • Runways Design and • Concrete truck chutes,pumps, and internals shall be washed out only Installation into formed areas awaiting installation of concrete or asphalt. Specifications • Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling. Hand tools including,but not limited to, screeds, shovels,rakes, floats, and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. • Equipment that cannot be easily moved, such as concrete pavers, shall only be washed in areas that do not directly drain to natural or constructed stormwater conveyances. • Washdown from areas such as concrete aggregate driveways shall not drain directly to natural or constructed stormwater conveyances. • When no formed areas are available, washwater and leftover product shall be contained in a lined container. Contained concrete shall be disposed of in a manner that does not violate groundwater or surface water quality standards. Maintenance Containers shall be checked for holes in the liner daily during concrete Standards pours and repaired the same day. February 2005 Volume 11- Construction Stormwater Pollution Prevention 4-43 BMP C152: Sawcutting and Surfacing Pollution Prevention Purpose Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting),both of which can violate the water quality standards in the receiving water. This BMP is intended to minimize and eliminate process water and slurry from entering waters of the State. Conditions of Use Anytime sawcutting or surfacing operations take place,these management practices shall be utilized. Sawcutting and surfacing operations include,but are not limited to,the following: • Sawing • Coring Grinding • Roughening • Hydro-demolition Bridge and road surfacing Design and • Slurry and cuttings shall be vacuumed during cutting and surfacing Installation operations. Specifications • Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight. • Slurry and cuttings shall not drain to any natural or constructed drainage conveyance. • Collected slurry and cuttings shall be disposed of in a manner that does not violate groundwater or surface water quality standards. • Process water that is generated during hydro-demolition, surface roughening or similar operations shall not drain to any natural or constructed drainage conveyance and shall be disposed of in a manner that does not violate groundwater or surface water quality standards. • Cleaning waste material and demolition debris shall be handled and disposed of in a manner that does not cause contamination of water. If the area is swept with a pick-up sweeper,the material must be hauled out of the area to an appropriate disposal site. Maintenance Continually monitor operations to determine whether slurry, cuttings, or Standards process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as berms,barriers, secondary containment, and vacuum trucks. 4-44 Volume 11— Construction Stormwater Pollution Prevention February 2005 'L BMP C160: Certified Erosion and Sediment Control Lead Purpose The project proponent designates at least one person as the responsible representative in charge of erosion and sediment control (ESC), and water quality protection. The designated person shall be the Certified Erosion and Sediment Control Lead(CESCL)who is responsible for ensuring compliance with all local, state, and federal erosion and sediment control and water quality requirements. Conditions of Use A CESCL shall be made available on projects one acre or larger that discharge stormwater to surface waters of the state • The CESCL shall: • Have a current certificate proving attendance in an erosion and sediment control training course that meets the minimum ESC training and certification requirements established by Ecology (see details below). Ecology will maintain a list of ESC training and certification providers at: www.epy.wa. og_v/programs/wq/stormwater. OR • Be a Certified Professional in Erosion and Sediment Control (CPESC); for additional information go to: www.cpesc.net Specifications . Certification shall remain valid for three years. • The CESCL shall have authority to act on behalf of the contractor or developer and shall be available, on call, 24 hours per day throughout the period of construction. • The Construction SWPPP shall include the name,telephone number, fax number, and address of the designated CESCL. • A CESCL may provide inspection and compliance services for multiple construction projects in the same geographic region. Duties and responsibilities of the CESCL shall include, but are not limited to the following: • Maintaining permit file on site at all times which includes the SWPPP and any associated permits and plans. • Directing BMP installation, inspection, maintenance, modification, and removal. • Updating all project drawings and the Construction SWPPP with changes made. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-47 • Keeping daily logs, and inspection reports. Inspection reports should include: •Inspection date/time. •Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection. •A summary or list of all BMPs implemented, including observations of all erosion/sediment control structures or practices. The following shall be noted: 1) Locations of BMPs inspected, 2)Locations of BMPs that need maintenance, 3)Locations of BMPs that failed to operate as designed or intended,and 4) Locations of where additional or different BMPs are required. •Visual monitoring results, including a description of discharged stormwater. The presence of suspended sediment,turbid water, discoloration, and oil sheen shall be noted, as applicable. •Any water quality monitoring performed during inspection. •General comments and notes, including a brief description of any BMP repairs,maintenance or installations made as a result of the inspection. • Facilitate,participate in,and take corrective actions resulting from inspections performed by outside agencies or the owner. 4-48 Volume 11— Construction Stormwater Pollution Prevention February 2005 Minimum Requirements for ESC Training and Certification Courses General Requirements 1. The course shall teach the construction stormwater pollution prevention guidance provided in the most recent version of: a. The Washington State Dept. of Ecology Stormwater Management Manual for Western Washington, b. Other equivalent stormwater management manuals approved by Ecology. 2. Upon completion of course, each attendee shall receive documentation of certification, including, at a minimum,a wallet-sized card that certifies completion of the course. Certification shall remain valid for three years. Recertification may be obtained by completing the 8-hour refresher course or by taking the initial 16-hour training course again. 3. The initial certification course shall be a minimum of 16 hours (with a reasonable time allowance for lunch,breaks, and travel to and from field) and include a field element and test. a. The field element must familiarize students with the proper installation, maintenance and inspection of common erosion and sediment control BMPs including,but not limited to,blankets, check dams, silt fence, straw mulch, plastic, and seeding. b. The test shall be open book and a passing score is not required for certification. Upon completion of the test, the correct answers shall be provided and discussed. 4. The refresher course shall be a minimum of 8 hours and include a test. a. The refresher course shall include: i. Applicable updates to the Stormwater Management Manual that is used to teach the course, including new or updated BMPs; and ii. Applicable changes to the NPDES General Permit for Construction Activities. b. The refresher course test shall be open book and a passing score is not required for certification. Upon completion of the test,the correct answers shall be provided and discussed. c. The refresher course may be taught using an alternative format(e.g. internet, CD ROM, etc.) if the module is approved by Ecology. Required Course Elements 1. Erosion and Sedimentation Impacts a. Examples/Case studies February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-49 2. Erosion and Sedimentation Processes a. Definitions b. Types of erosion c. Sedimentation i. Basic settling concepts ii. Problems with clays/turbidity 3. Factors Influencing Erosion Potential a. Soil b. Vegetation c. Topography d. Climate 4. Regulatory Requirements a. NPDES - Construction Stormwater General Permit b. Local requirements and permits c. Other regulatory requirements 5. Stormwater Pollution Prevention Plan(SWPPP) a. SWPPP is a living document-should be revised as necessary b. 12 Elements of a SWPPP; discuss suggested BMPs(with examples) 1. Mark Clearing Limits 2. Establish Construction Access 3. Control Flow Rates 4. Install Sediment Controls 5. Stabilize Soils 6. Protect Slopes 7. Protect Drain Inlets 8. Stabilize Channels and Outlets 9. Control Pollutants 10. Control De-watering 11. Maintain BMPs 12. Manage the Project 6. Monitorin ortin ecordkee in �aP � p g a. Site inspections/visual monitoring i. Disturbed areas I ii. BMPs iii. Stormwater discharge points b. Water quality sampling/analysis i. Turbidity ii. pH c. Monitoring frequency i. Set by NPDES permit ii. Inactive sites -reduced frequency I 4-50 Volume 11— Construction Stormwater Pollution Prevention February 2005 it d. Adaptive Management i. When monitoring indicates problem,take appropriate action(e.g. install/maintain BMPs) ii. Document the corrective action(s) in SWPPP e. Reporting i. Inspection reports/checklists ii. Discharge Monitoring Reports (DMR) iii. Non-compliance notification Instructor Qualifications 1. Instructors must be qualified to effectively teach the required course elements. 2. At a minimum, instructors must have: a. Current certification as a Certified Professional in Erosion and Sediment Control (CPESC), or b. Completed a training program for teaching the required course elements, or c. The academic credentials and instructional experience necessary for teaching the required course elements. 3. Instructors must demonstrate competent instructional skills and knowledge of the applicable subject matter. February 2005 Volume II— Construction Stormwater Pollution Prevention 4-51 BMP C162: Scheduling Purpose Sequencing a construction project reduces the amount and duration of soil exposed to erosion by wind, rain,runoff, and vehicle tracking. Conditions of Use The construction sequence schedule is an orderly listing of all major land- disturbing activities together with the necessary erosion and sedimentation control measures planned for the project. This type of schedule guides the contractor on work to be done before other work is started so that serious erosion and sedimentation problems can be avoided. Following a specified work schedule that coordinates the timing of land- disturbing activities and the installation of control measures is perhaps the most cost-effective way of controlling erosion during construction. The removal of surface ground cover leaves a site vulnerable to accelerated erosion. Construction procedures that limit land clearing,provide timely installation of erosion and sedimentation controls, and restore protective cover quickly can significantly reduce the erosion potential of a site. Design • Avoid rainy periods. Considerations . Schedule projects to disturb only small portions of the site at any one time. Complete grading as soon as possible. Immediately stabilize the disturbed portion before grading the next portion. Practice staged seeding in order to revegetate cut and fill slopes as the work progresses. I 4-54 Volume 11— Construction Stormwater Pollution Prevention February 2005 BMP C202: Channel Lining Purpose To protect erodible channels by providing a channel liner using either blankets or riprap. Conditions of Use When natural soils or vegetated stabilized soils in a channel are not adequat( to prevent channel erosion. • When a permanent ditch or pipe system is to be installed and a temporary measure is needed. • In almost all cases, synthetic and organic coconut blankets are more effective than riprap for protecting channels from erosion. Blankets can be used with and without vegetation. Blanketed channels can be designed to handle any expected flow and longevity requirement. Some synthetic blankets have a predicted life span of 50 years or more, even in sunlight. • Other reasons why blankets are better than rock include the availability of blankets over rock. In many areas of the state,rock is not easily obtainable or is very expensive to haul to a site. Blankets can be delivered anywhere. Rock requires the use of dump trucks to haul and heavy equipment to place. Blankets usually only require laborers with hand tools, and sometimes a backhoe. • The Federal Highway Administration recommends not using flexible liners whenever the slope exceeds 10 percent or the shear stress exceeds 8 lbs/ft2. Design and See BMP C122 for information on blankets. Installation Since riprap is used where erosion potential is high, construction must be Specifications sequenced so that the riprap is put in place with the minimum possible delay. • Disturbance of areas where riprap is to be placed should be undertaken only when final preparation and placement of the riprap can follow immediately behind the initial disturbance. Where riprap is used for outlet protection,the riprap should be placed before or in conjunction with the construction of the pipe or channel so that it is in place when the pipe or channel begins to operate. • The designer, after determining the riprap size that will be stable under the flow conditions, shall consider that size to be a minimum size and then,based on riprap gradations actually available in the area, select the size or sizes that equal or exceed the minimum size. The possibility of drainage structure damage by children shall be considered in selecting a riprap size, especially if there is nearby water or a gully in which to toss the stones. • Stone for riprap shall consist of field stone or quarry stone of approximately rectangular shape. The stone shall be hard and angular and of such quality that it will not disintegrate on exposure to water or February 2005 Volume 11- Construction Stormwater Pollution Prevention 4-63 weathering and it shall be suitable in all respects for the purpose intended. • Rubble concrete may be used provided it has a density of at least 150 pounds per cubic foot,and otherwise meets the requirement of this standard and specification. • A lining of engineering filter fabric (geotextile) shall be placed between the riprap and the underlying soil surface to prevent soil movement into or through the riprap. The geotextile should be keyed in at the top of the bank. • Filter fabric shall not be used on slopes greater than 1-1/2:1 as slippage may occur. It should be used in conjunction with a layer of coarse aggregate (granular filter blanket)when the riprap to be placed is 12 inches and larger. 4-64 Volume 11— Construction Stormwater Pollution Prevention February 2005 BMP C207: Check Dams Purpose Construction of small dams across a swale or ditch reduces the velocity of concentrated flow and dissipates energy at the check dam. Conditions of Use Where temporary channels or permanent channels are not yet vegetated, channel lining is infeasible, and velocity checks are required. • Check dams may not be placed in streams unless approved by the State Department of Fish and Wildlife. Check dams may not be placed in wetlands without approval from a permitting agency. • Check dams shall not be placed below the expected backwater from any salmonid bearing water between October 1 and May 31 to ensure that there is no loss of high flow refuge habitat for overwintering juvenile salmonids and emergent salmonid fry. Design and Whatever material is used,the dam should form a triangle when viewed Installation from the side. This prevents undercutting as water flows over the face of Specifications the dam rather than falling directly onto the ditch bottom. Check dams in association with sumps work more effectively at slowing flow and retaining sediment than just a check dam alone. A deep sump should be provided immediately upstream of the check dam. • In some cases, if carefully located and designed, check dams can remain as permanent installations with very minor regrading. They may be left as either spillways, in which case accumulated sediment would be graded and seeded, or as check dams to prevent further sediment from leaving the site. • Check dams can be constructed of either rock or pea-gravel filled bags. Numerous new products are also available for this purpose. They tend to be re-usable, quick and easy to install, effective, and cost efficient. • Check dams should be placed perpendicular to the flow of water. • The maximum spacing between the dams shall be such that the toe of the upstream dam is at the same elevation as the top of the downstream dam. • Keep the maximum height at 2 feet at the center of the dam. • Keep the center of the check dam at least 12 inches lower than the outer edges at natural ground elevation. • Keep the side slopes of the check dam at 2:1 or flatter. • Key the stone into the ditch banks and extend it beyond the abutments a minimum of 18 inches to avoid washouts from overflow around the dam. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-75 • Use filter fabric foundation under a rock or sand bag check dam. If a blanket ditch liner is used,this is not necessary. A piece of organic or synthetic blanket cut to fit will also work for this purpose. • Rock check dams shall be constructed of appropriately sized rock. The rock must be placed by hand or by mechanical means(no dumping of rock to form dam)to achieve complete coverage of the ditch or swale and to ensure that the center of the dam is lower than the edges. The rock used must be large enough to stay in place given the expected design flow through the channel. • In the case of grass-lined ditches and swales, all check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale -unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • Ensure that channel appurtenances, such as culvert entrances below check dams, are not subject to damage or blockage from displaced stones. Figure 4.13 depicts a typical rock check dam. Maintenance Check dams shall be monitored for performance and sediment Standards accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the sump depth. • Anticipate submergence and deposition above the check dam and erosion from high flows around the edges of the dam. • If significant erosion occurs between dams, install a protective riprap liner in that portion of the channel. 4-76 Volume 11- Construction Stormwater Pollution Prevention February 2005 View Looking Upstream A 18" (0.5m) 12" (150mm) -0 -,°°o ;3 o0 i,./ / 24"(0.6m) e o NOTE: moA off; •p.� . Key stone into channel banks and / /\\X extend it beyond the abutments a \ i\ minimum of 18" (0.5m) to prevent A flow around dam. Section A - A FLOW 24" (0.6m) �o°o po ?pro O o o° 8' (2.4m) Spacing Between Check Dams •L'=the distance such that points •A' and •B' are of equal elevation. o, POINT'A' �POINT•B' /\/\\\�%\//%\//%\/\\//\\//j//\// / �a •� moo.., NOT TO SCALE Figure 4.13—Check Dams February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-77 BMP C209: Outlet Protection Purpose Outlet protection prevents scour at conveyance outlets and minimizes the potential for downstream erosion by reducing the velocity of concentrated stormwater flows. Conditions of use Outlet protection is required at the outlets of all ponds, pipes, ditches, or other conveyances, and where runoff is conveyed to a natural or manmade drainage feature such as a stream,wetland, lake, or ditch. Design and The receiving channel at the outlet of a culvert shall be protected from Installation erosion by rock lining a minimum of 6 feet downstream and extending up Specifications the channel sides a minimum of 1—foot above the maximum tailwater elevation or 1-foot above the crown,whichever is higher. For large pipes (more than 18 inches in diameter),the outlet protection lining of the channel is lengthened to four times the diameter of the culvert. • Standard wingwalls, and tapered outlets and paved channels should also be considered when appropriate for permanent culvert outlet protection. (See WSDOT Hydraulic Manual, available through WSDOT Engineering Publications). • Organic or synthetic erosion blankets, with or without vegetation, are usually more effective than rock, cheaper, and easier to install. Materials can be chosen using manufacturer product specifications. ASTM test results are available for most products and the designer can choose the correct material for the expected flow. • With low flows,vegetation(including sod) can be effective. The following guidelines shall be used for riprap outlet protection: 1. If the discharge velocity at the outlet is less than 5 fps(pipe slope less than 1 percent), use 2-inch to 8-inch riprap. Minimum thickness is 1-foot. 2. For 5 to 10 fps discharge velocity at the outlet(pipe slope less than 3 percent), use 24-inch to 4-foot riprap. Minimum thickness is 2 feet. 3. For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), an engineered energy dissipater shall be used. Filter fabric or erosion control blankets should always be used under riprap to prevent scour and channel erosion. New pipe outfalls can provide an opportunity for low-cost fish habitat improvements. For example, an alcove of low-velocity water can be created by constructing the pipe outfall and associated energy dissipater back from the stream edge and digging a channel, over- widened to the upstream side, from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shelter during 4-80 Volume 11— Construction Stormwater Pollution Prevention February 2005 high flows. Bank stabilization, bioengineering, and habitat features may be required for disturbed areas. See Volume V for more information on outfall system design. Maintenance • Inspect and repair as needed. Standards • Add rock as needed to maintain the intended function. • Clean energy dissipater if sediment builds up. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-81 BMP C220: Storm Drain Inlet Protection Purpose To prevent coarse sediment from entering drainage systems prior to permanent stabilization of the disturbed area. Conditions of Use Where storm drain inlets are to be made operational before permanent stabilization of the disturbed drainage area. Protection should be provided for all storm drain inlets downslope and within 500 feet of a disturbed or construction area,unless the runoff that enters the catch basin will be conveyed to a sediment pond or trap. Inlet protection may be used anywhere to protect the drainage system. It is likely that the drainage system will still require cleaning. Table 4.9 lists several options for inlet protection. All of the methods for storm drain inlet protection are prone to plugging and require a high frequency of maintenance. Drainage areas should be limited to 1 acre or less. Emergency overflows may be required where stormwater ponding would cause a hazard. If an emergency overflow is provided, additional end-of-pipe treatment may be required. Table 4.9 Storm Drain Inlet Protetion Applicable for Type of Inlet Emergency Paved/ Earthen Protection Overflow Surfaces Conditions of Use Drop Inlet Protection Excavated drop inlet Yes, Earthen Applicable for heavy flows. Easy protection temporary to maintain. Large area flooding will Requirement: 30'X 307acre occur Block and gravel drop Yes Paved or Earthen Applicable for heavy concentrated inlet protection flows. Will not pond. Gravel and wire drop No Applicable for heavy concentrated inlet protection flows. Will pond. Can withstand traffic. Catch basin filters Yes Paved or Earthen Frequent maintenance required. Curb Inlet Protection Curb inlet protection Small capacity Paved Used for sturdy, more compact with a wooden weir overflow installation. Block and gravel curb Yes Paved Sturdy,but limited filtration. inlet protection Culvert Inlet Protection Culvert inlet sediment 18 month expected life. trap 4-82 Volume 11— Construction Stormwater Pollution Prevention February 2005 Design and Excavated Drop Inlet Protection -An excavated impoundment around the Installation storm drain. Sediment settles out of the stormwater prior to entering the Specifications storm drain. • Depth 1-2 ft as measured from the crest of the inlet structure. • Side Slopes of excavation no steeper than 2:1. • Minimum volume of excavation 35 cubic yards. • Shape basin to fit site with longest dimension oriented toward the longest inflow area. • Install provisions for draining to prevent standing water problems. • Clear the area of all debris. • Grade the approach to the inlet uniformly. • Drill weep holes into the side of the inlet. • Protect weep holes with screen wire and washed aggregate. • Seal weep holes when removing structure and stabilizing area. • It may be necessary to build a temporary dike to the down slope side of the structure to prevent bypass flow. Block and Gravel Filter- A barrier formed around the storm drain inlet with standard concrete blocks and gravel. See Figure 4.14. Height 1 to 2 feet above inlet. • Recess the first row 2 inches into the ground for stability. • Support subsequent courses by placing a 2x4 through the block opening. Do not use mortar. • Lay some blocks in the bottom row on their side for dewatering the pool. • Place hardware cloth or comparable wire mesh with 1/2-inch openings over all block openings. • Place gravel just below the top of blocks on slopes of 2:1 or flatter. An alternative design is a gravel donut. Inlet slope of 3:1. • Outlet slope of 2:1. 1-foot wide level stone area between the structure and the inlet. • Inlet slope stones 3 inches in diameter or larger. • Outlet slope use gravel %z-to 3/a-inch at a minimum thickness of 1-foot. February 2005 Volume 11- Construction Stormwater Pollution Prevention 4-83 Plan View A Drain Grate °'_zF00'oC—.b a ° .moo • o� o 0 o D• ¢O� 0 0.0 OogQ - o 000 � '�oog O�0 a `_oo•10 a:0 b° Concrete �0 0 ° o Block d�Q oo'p� NMI Oo�� Q o � o 0. QO,Q�O oQ4 4 p Gravel 'p o"4�0 °d o Backfill ° ° p0 o oo QOp 4 � cVSy(O�O :O��d�{000 �V oo0 0V.4 A Section A - A Concrete Block Wire Screen or Filter Fabric Gravel Backfill Overflow Water Ponding Height o e Water • po \//\\//\\//\\//\\// Drop Inlet Notes: 1.Drop inlet sediment barriers are to be used for small,nearly level drainage areas.(less than 5%) 2.Excavate a basin of sufficient size adjacent to the drop inlet. 3.The top of the structure(ponding height)must be well below the ground elevation downslope to prevent runoff from bypassing the inlet. A temporary dike may be necessary on the dowslope side of the structure. Figure 4.14— Block and Gravel Filter Gravel and Wire Mesh Filter-A gravel barrier placed over the top of the inlet. This structure does not provide an overflow. • Hardware cloth or comparable wire mesh with r/Z-inch openings. • Coarse aggregate. • Height 1-foot or more, 18 inches wider than inlet on all sides. • Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot beyond each side of the inlet structure. • If more than one strip of mesh is necessary, overlap the strips. • Place coarse aggregate over the wire mesh. • The depth of the gravel should be at least 12 inches over the entire inlet opening and extend at least 18 inches on all sides. 4-84 Volume 11— Construction Stormwater Pollution Prevention February 2005 Catchbasin Filters -Inserts should be designed by the manufacturer for use at construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required,which may be daily for heavy sediment loads. The maintenance requirements can be reduced by combining a catchbasin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of- way. • 5 cubic feet of storage. • Dewatering provisions. • High-flow bypass that will not clog under normal use at a construction site. • The catchbasin filter is inserted in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir—Barrier formed around a curb inlet with a wooden frame and gravel. • Wire mesh with 1/2-inch openings. • Extra strength filter cloth. • Construct a frame. • Attach the wire and filter fabric to the frame. • Pile coarse washed aggregate against wire/fabric. • Place weight on frame anchors. Block and Gravel Curb Inlet Protection—Barrier formed around an inlet with concrete blocks and gravel. See Figure 4.14. • Wire mesh with %2-inch openings. • Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. • Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the inlet and abutting the spacer blocks. • Place wire mesh over the outside vertical face. • Pile coarse aggregate against the wire to the top of the barrier. Curb and Gutter Sediment Barrier—Sandbag or rock berm(riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure 4.16. • Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm sized to sediment trap standards for protecting a culvert inlet. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-85 Maintenance • Catch basin filters should be inspected frequently, especially after Standards storm events. If the insert becomes clogged, it should be cleaned or replaced. • For systems using stone filters: If the stone filter becomes clogged with sediment,the stones must be pulled away from the inlet and cleaned or replaced. Since cleaning of gravel at a construction site may be difficult, an alternative approach would be to use the clogged stone as fill and put fresh stone around the inlet. • Do not wash sediment into storm drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appropriate. 4-86 Volume 11— Construction Stormwater Pollution Prevention February 2005 Plan View CBack of Sidewalk A Catch Basin 2x4 Wood Stud Back of Curb Concrete Block Curb Inlet 0 .4,0 M 02 0 LP R 10 0 Wire Screen r Filter Fabric A- Concrete Block 3/4 Section A - A (2 Drain Gravel 0mm) W Drain Gravel (20mm) Ponding Height Concrete Block Overfi Curb Inlet Wire Screen or Filter Fabric 4 Wood StudCatch Basin (100x50 Timber Stud) NOTES: 1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shall allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. Figure 4.15- Block and Gravel Curb Inlet Protection February 2005 Volume 11- Construction Stormwater Pollution Prevention 4-87 Plan View Back of Sidewalk Burlap Sacks to Catch Basin Overlap onto Curb Curb Inlet Back of Curb RUNOFF RUNOFF SPILLWAY Gravel Filled Sandbags Stacked Tightly NOTES: 1.Place curb type sediment barriers on gently sloping street segments,where water can pond and allow sediment to separate from runoff. 2.Sandbags of either burlap or woven'geotextile'fabric,are filled with gravel,layered and packed tightly. 3.Leave a one sandbag gap in the top row to provide a spillway for overflow. 4.Inspect barriers and remove sediment after each storm event.Sediment and gravel must be removed from the traveled way immediately. Figure 4.16—Curb and Gutter Barrier 4-88 Volume 11— Construction Stormwater Pollution Prevention February 2005 BMP C233: Silt Fence Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. See Figure 4.19 for details on silt fence construction. Conditions of Use Silt fence may be used downslope of all disturbed areas. • Silt fence is not intended to treat concentrated flows,nor is it intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a silt fence,rather than by a sediment pond, is when the area draining to the fence is one acre or less and flow rates are less than 0.5 cfs. • Silt fences should not be constructed in streams or used in V-shaped ditches.They are not an adequate method of silt control for anything deeper than sheet or overland flow. Joints in filter fabric shall be spliced at posts.Use staples,wire rings or 2"x2"by 14 Ga.wire or equivalent to attach fabric to posts equivalent,if standard T strength fabric used Filter fabric —� CV �g/m �I ITS Minimum 4"x4"trench N L Backfill trench with native soil — Post spacing may be increased or 314"-1.5"washed gravel to 8'if wire backing is used 2"x2"wood posts,steel fence posts,or equivalent Figure 4.19 — Silt Fence Design and • Drainage area of 1 acre or less or in combination with sediment basin Installation in a larger site. Specifications • Maximum slope steepness(normal (perpendicular)to fence line) 1:1. Maximum sheet or overland flow path length to the fence of 100 feet. No flows greater than 0.5 cfs. • The geotextile used shall meet the following standards. All geotextile properties listed below are minimum average roll values(i.e.,the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 4.10): 4-94 Volume 11— Construction Stormwater Pollution Prevention February 2005 Table 4.10 Geotextile Standards Polymeric Mesh AOS 0.60 mm maximum for slit film wovens(#30 sieve). 0.30 (ASTM D4751) mm maximum for all other geotextile types(#50 sieve). 0.15 mm minimum for all fabric types(#100 sieve). Water Permittivity 0.02 sec-1 minimum (ASTM D4491) Grab Tensile Strength 180 lbs.Minimum for extra strength fabric. (ASTM D4632) 100 Is minimum for standard strength fabric. Grab Tensile Strength 30%maximum (ASTM D4632) Ultraviolet Resistance 70%minimum (ASTM D4355) • Standard strength fabrics shall be supported with wire mesh, chicken wire,2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the fabric. Silt fence materials are available that have synthetic mesh backing attached. • Filter fabric material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construction life at a temperature range of 0°F. to 120°F. • 100 percent biodegradable silt fence is available that is strong, long lasting, and can be left in place after the project is completed, if permitted by local regulations. • Standard Notes for construction plans and specifications follow. Refer to Figure 4.19 for standard silt fence details. The contractor shall install and maintain temporary silt fences at the locations shown in the Plans. The silt fences shall be constructed in the areas of clearing, grading, or drainage prior to starting those activities. A silt fence shall not be considered temporary if the silt fence must function beyond the life of the contract. The silt fence shall prevent soil carried by runoff water from going beneath,through, or over the top of the silt fence,but shall allow the water to pass through the fence. The minimum height of the top of silt fence shall be 2 feet and the maximum height shall be 2'/2 feet above the original ground surface. The geotextile shall be sewn together at the point of manufacture, or at an approved location as determined by the Engineer,to form geotextile lengths as required. All sewn seams shall be located at a support post. Alternatively,two sections of silt fence can be overlapped, provided the Contractor can demonstrate,to the satisfaction of the Engineer,that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-95 The geotextile shall be attached on the up-slope side of the posts and support system with staples,wire, or in accordance with the manufacturer's recommendations. The geotextile shall be attached to the posts in a manner that reduces the potential for geotextile tearing at the staples, wire, or other connection device. Silt fence back-up support for the geotextile in the form of a wire or plastic mesh is dependent on the properties of the geotextile selected for use. If wire or plastic back-up mesh is used, the mesh shall be fastened securely to the up-slope of the posts with the geotextile being up-slope of the mesh back-up support. The geotextile at the bottom of the fence shall be buried in a trench to a minimum depth of 4 inches below the ground surface. The trench shall be backfilled and the soil tamped in place over the buried portion of the geotextile, such that no flow can pass beneath the fence and scouring can not occur. When wire or polymeric back-up support mesh is used,the wire or polymeric mesh shall extend into the trench a minimum of 3 inches. The fence posts shall be placed or driven a minimum of 18 inches. A minimum depth of 12 inches is allowed if topsoil or other soft subgrade soil is not present and a minimum depth of 18 inches cannot be reached. Fence post depths shall be increased by 6 inches if the fence is located on slopes of 3:1 or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. Silt fences shall be located on contour as much as possible, except at the ends of the fence,where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. If the fence must cross contours, with the exception of the ends of the fence, gravel check dams placed perpendicular to the back of the fence shall be used to minimize concentrated flow and erosion along the back of the fence. The gravel check dams shall be approximately 1- foot deep at the back of the fence. It shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. The gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. The gravel check dams shall be located every 10 feet along the fence where the fence must cross contours. The slope of the fence line where contours must be crossed shall not be steeper than 3:1. Wood, steel or equivalent posts shall be used. Wood posts shall have minimum dimensions of 2 inches by 2 inches by 3 feet minimum length,and shall be free of defects such as knots, splits, or gouges. 4-96 Volume 11— Construction Stormwater Pollution Prevention February 2005 Steel posts shall consist of either size No. 6 rebar or larger,ASTM A 120 steel pipe with a minimum diameter of 1-inch, U, T,L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. or other steel posts having equivalent strength and bending resistance to the post sizes listed. The spacing of the support posts shall be a maximum of 6 feet. Fence back-up support, if used, shall consist of steel wire with a maximum mesh spacing of 2 inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to ultraviolet radiation as the geotextile it supports. • Silt fence installation using the slicing method specification details follow. Refer to Figure 4.20 for slicing method details. The base of both end posts must be at least 2 to 4 inches above the top of the silt fence fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary,to mark base points before installation. Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet apart in standard applications. Install posts 24 inches deep on the downstream side of the silt fence, and as close as possible to the fabric, enabling posts to support the fabric from upstream water pressure. Install posts with the nipples facing away from the silt fence fabric. Attach the fabric to each post with three ties, all spaced within the top 8 inches of the fabric. Attach each tie diagonally 45 degrees through the fabric, with each puncture at least 1 inch vertically apart. In addition, each tie should be positioned to hang on a post nipple when tightening to prevent sagging. Wrap approximately 6 inches of fabric around the end posts and secure with 3 ties. No more than 24 inches of a 36-inch fabric is allowed above ground level. The rope lock system must be used in all ditch check applications. The installation should be checked and corrected for any deviation before compaction. Use a flat-bladed shovel to tuck fabric deeper into the ground if necessary. Compaction is vitally important for effective results. Compact the soil immediately next to the silt fence fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-97 • Any damage shall be repaired immediately. Maintenance . If concentrated flows are evident uphill of the fence,they must be Standards intercepted and conveyed to a sediment pond. • It is important to check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs,replace the fence or remove the trapped sediment. • Sediment deposits shall either be removed when the deposit reaches approximately one-third the height of the silt fence, or a second silt fence shall be installed. • If the filter fabric (geotextile)has deteriorated due to ultraviolet breakdown it shall be replaced. Pond.ng height POST SPACING: max.24- 7'max.on open runs 4'max.on pealing areas If .............. ..•...............Top of Fabric T 777717177 attach fabric to BC'It upstreaw side et pmt 7 8• FLOW.. — 411 Drive over each side M POST DEPTH: sNt tome 2 to 4 times As much below ground with device exerting as tabAc above ground 60 p.s.l.or greater ' 100%cep corn actia(w 100% psctlon ��la uachmord w tlouDlas sreripgn. Li i / ♦ � ,'/\\\/� ATTACHMENT DETAILS: \\\�\ �" C\\�\\\\�\ •Gather fabric at posts,If needed. .Utitf:e thee bee per paR ad wiRhln top a-or fabric. 'Position mn of tie 1 apan any,puncturing holes verticegy nwrrx •Hang each lie on a post nipple and tigMan securety. No more than 24"of a 36"fabde use cable bes(50RY4 or sal wire, is allowed above ground. Roll of sit fence F— Opgration post instated after compaction Fabric O above Slit Fence /ground ��' 'a.dam@ 2 w;����• %. 200 300mm '� y' , v Horizontal chiser P1** Slicing blade (76 mm width) (18 trim width) Compreged kutalation Vibratory plow is not acceptable because of horizontal compaction Figure 4.20 —Silt Fence Installation by Slicing Method 4-98 Volume 11— Construction Stormwater Pollution Prevention February 2005 BMP C235: Straw Wattles Purpose Straw wattles are temporary erosion and sediment control barriers consisting of straw that is wrapped in biodegradable tubular plastic or similar encasing material. They reduce the velocity and can spread the flow of rill and sheet runoff,and can capture and retain sediment. Straw wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. The wattles are placed in shallow trenches and staked along the contour of disturbed or newly constructed slopes. See Figure 4.21 for typical construction details. Conditions of Use • Disturbed areas that require immediate erosion protection. • Exposed soils during the period of short construction delays, or over winter months. • On slopes requiring stabilization until permanent vegetation can be established. • Straw wattles are effective for one to two seasons. • If conditions are appropriate,wattles can be staked to the ground using willow cuttings for added revegetation. • Rilling can occur beneath wattles if not properly entrenched and water can pass between wattles if not tightly abutted together. Design Criteria • It is critical that wattles are installed perpendicular to the flow direction and parallel to the slope contour. • Narrow trenches should be dug across the slope on contour to a depth of 3 to 5 inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall,the trenches should be dug to a depth of 5 to 7 inches, or 1/2 to 2/3 of the thickness of the wattle. • Start building trenches and installing wattles from the base of the slope and work up. Excavated material should be spread evenly along the uphill slope and compacted using hand tamping or other methods. • Construct trenches at contour intervals of 3 to 30 feet apart depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. • Install the wattles snugly into the trenches and abut tightly end to end. Do not overlap the ends. • Install stakes at each end of the wattle, and at 4-foot centers along entire length of wattle. • If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. • At a minimum, wooden stakes should be approximately 3/4 x 3/4 x 24 inches. Willow cuttings or 3/8-inch rebar can also be used for stakes. 4-100 Volume 11— Construction Stormwater Pollution Prevention February 2005 Maintenance . Stakes should be driven through the middle of the wattle, leaving 2 to 3 Standards inches of the stake protruding above the wattle. • Wattles may require maintenance to ensure they are in contact with soil and thoroughly entrenched, especially after significant rainfall on steep sandy soils. • Inspect the slope after significant storms and repair any areas where wattles are not tightly abutted or water has scoured beneath the wattles. 3'-4' (1.2m) Straw Rolls Must Be Placed Along /\\ Slope Contours j\\ Adjacent rolls shall tightly abut i 10'-25'(3-8m) Spacing Dependson \ ll Type d Steepness \ �i/ Sediment,organic matter, Slope \\,\ and native seeds are captured behind the rolls. 3"-5"(75-125mm) 8"-10"DIA. (200-250mm) Live Stake �,\\ _7 1" X 1" Stake not to scale (25 x 25mm) l l� NOTE: 1.Straw roll installation requires the placement and secure staking of the roll in a trench,3"-5"(75-125mm) deep,dug on contour. runoff must not be allowed to run under or around roll. Figure 4.21 —Straw Wattles February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-101 Blue Heron Resort- Storrowater Pollution Prevention Plan Appendix C — Alternative BMPs The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. Element#1 - Mark Clearing Limits Element#2 -Establish Construction Access Element 43 - Control Flow Rates Element#4 - Install Sediment Controls Advanced BMPs: Element 95 - Stabilize Soils Element #6 -Protect Slopes Element 48 - Stabilize Channels and Outlets Element#10- Control Dewatering Additional Advanced BMPs to Control Dewatering: 28 Blue Heron Resort- Stormwater Pollution Prevention Plan Appendix D — General Permit 29 Blue Heron Resort-Stormwater Pollution Prevention Plan Appendix E — Site Inspection Forms (and Site Log) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document, but this is optional. However, it is mandatory that this SWPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. C. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations of BMPs inspected, ii. locations of BMPs that need maintenance, iii. the reason maintenance is needed, iv. locations of BMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s) why e. A description of stormwater discharged from the site. The presence of suspended sediment,turbid water, discoloration, and/or oil sheen shall be noted, as applicable. f. A description of any water quality monitoring performed during inspection, and the results of that monitoring. g. General comments and notes, including a brief description of any BMP r repairs,maintenance or installations made as a result of the inspection. h. A statement that, in the judgment of the person conducting the site inspection,the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance,the inspection report shall include a summary of the 30 Blue Heron Resort-Stonnwater Pollution Prevention Plan remedial actions required to bring the site back into compliance, as well as a schedule of implementation. i. Name,title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete,to the best of my knowledge and belief'. When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s)to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices(BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment,the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.F of the permit. 31 Blue Heron Resort- Stormwater Pollution Prevention Plan Site Inspection Form General Information Project Name: Inspector Name: Title: CESCL# : Date: Time: Inspection Type: ❑ After a rain event ❑ Weekly ❑ Turbidity/transparency benchmark exceedance ❑ Other Weather Precipitation Since last inspection In last 24 hours Description of General Site Conditions: Inspection of BMPs Element]: Mark Clearing Limits BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 2: Establish Construction Access BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP 32 Blue Heron Resort- Stormwater Pollution Prevention Plan Element 3: Control Flow Rates BMP: Inspected Functioning Location Y N —Y —N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP Element 4: Install Sediment Controls BMP: Inspected Functioning Location Y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N Y 7N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 33 Blue Heron Resort- Stormwater Pollution Prevention Plan Element S: Stabilize Soils BMP: Inspected Functioning Location Y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY7N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP Element 6: Protect Slopes BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP BMP: Location Inspected NFunctioning Problem/Corrective Action FTY N] NIP BMP: Inspected Functioning Location Y N Y N NIP Problem/Corrective Action 34 Blue Heron Resort- Stormwater Pollution Prevention Plan Element 7: Protect Drain Inlets BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 8: Stabilize Channels and Outlets BMP: Inspected Functioning Location Y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY7N NIP 35 Blue Heron Resort- Stormwater Pollution Prevention Plan Element 9: Control Pollutants BMP: Inspected Functioning Location Y N Y N NIP Problem/Corrective Action BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP Element 10: Control Dewatering BMP: Location Inspected Functioning Problem/Corrective Action Y N FTY N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N f Y 7N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP 36 Blue Heron Resort- Stormwater Pollution Prevention Plan Stormwater Discharges From the Site Observed? Y Problem/Corrective Action Location Turbidity Discoloration Sheen Location Turbidity Discoloration Sheen 37 Blue Heron Resort- Stormwater Pollution Prevention Plan Water Quality Monitoring Was any water quality monitoring conducted? ❑ Yes ❑ No If water quality monitoring was conducted, record results here: If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6 cm or less, was Ecology notified by phone within 24 hrs? ❑ Yes ❑ No If Ecology was notified, indicate the date, time, contact name and phone number below: Date: Time: Contact Name: Phone #: General Comments and Notes Include BMP repairs, maintenance, or installations made as a result of the inspection. Were Photos Taken? ❑ Yes ❑ No If photos taken, describe photos below: 38 L r Mason County Construction Stormwater Pollution Prevention Plan Checklist Project Name: J UE. pro r, Con-10 rYi r u v� County Project No. C—orri 2.0 i0 - GCYO- "1 Review Date: Construction SWPPP Reviewer: Minimum Requirements of the DOE 2005 Stormwater Manual The Stormwater checklist identifies the minimum requirements of the DOE 2005 Stormwater Manual. The Checklist is intended to identify the locations within the plan that addresses the minimum requirements. Mason County will not perform a technical evaluation of the submittal. Rather, the checklist provides a guide to allow Mason County to review the submittal and determine if the applicant has addressed the minimum features that make up a Stormwater plan. It is incumbent upon the applicant and his/her engineer to fulfill all the applicable requirements of the 2005 Stormwater Plan as it relates to the proposed project. Review by Mason County is intended to determine if the plan has addressed the minimum requirements. Applicant's engineer shall be responsible for the technical accuracy of the submitted Stormwater plan. During construction of the project, the stormwater plan engineer of record or his/her authorized representative shall inspect the site to ensure the stormwater plan is being implemented as designed. Upon completion of the project, the engineer or his authorized representative shall be required to certify that the stormwater plan has been implemented as designed. Failure to meet the minimum requirements could result in delay or rejection of the application until the deficiencies are corrected. Section I - Construction SWPPP Narrative 1. Construction Stormwater Pollution Prevention Elements tea. Describe how each of the Construction Stormwater Pollution Prevention Element has been addressed though the Construction SWPPP. v b. Identify the type and location of BMPs used to satisfy the required element. l lc. Written justification identifying the reason an element is not applicable to the proposal. 12 Required Elements - Construction Stormwater Pollution Prevention Plan ✓1. Mark Clearing Limits, See page/paragraph 5 11 2. Establish Construction Access, See page/paragraph513 ✓ 3. Control Flow Rates, See page/paragraph 611 c/4. Install Sediment Controls, See page/paragraph 5 _/5. Stabilize Soils, See page/paragraph -7 /G Stormwater Checklist DOE 2005 Manual.doc 1 Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist ✓"6. Protect Slopes, See page/paragraph 8 6 _✓7. Protect Drain Inlets, See page/paragraph 713 _✓8. Stabilize Channels and Outlets, See page/para raph _✓9. Control Pollutants, See page/paragraph O _✓10. Control De- Watering, See page/paragraph it _✓ 11. Maintain BMPs, See page/paragraph l 12. Manage the Project, See page/paragraph l 2. Project Description ✓a. Total project area. Acres Sq. Ft. .3ZZ,500 ✓b. Total proposed impervious area. Acres !.l Sq. Ft. '7 4 j a+00 V c. Total proposed are to be disturbed, included off-site borrow and fill areas. Ac.0.L Sq. Ft.�oo d. Total volumes of proposed cut and fill. Cubic Yards .325 C`,Cam, 27o GYF![,L. 3. Existing Site Conditions c/a. Description of the existing topography. See page/paragraph 312 Description of the existing vegetation. See page/paragraph 313 �/'c. Description of the existing drainage. See page/paragraph 315 4. Adjacent Areas I. Description of adjacent areas that may be affected by the site disturbance ✓ a. Streams, See page/paragraph U JA _✓ b. Lakes, See page/paragraph NIA ✓c. Wetlands, See page/paragraph ✓d. Residential Areas, See page/paragraph 307 2 ✓e. Roads, See page/paragraph 2 V f. Other, See page/paragraph f{o 4 Ca� 315 1/ II. Description of the downstream drainage path leading from the site to the receiving body of water. (Minimum distance of 400 yards), See page/paragraph 3 f 8 5. Critical Areas a. Description of critical areas that are on or adjacent to the site. See page/paragraph 00 CRITICAL A*25AS 3[3 b. Description of special requirements for working in or near critical areas. See page/paragraph AJJtA 6. Soils _ Description of on-site soils. 3 y a. Soil name(s) , See page/paragraph b. Soil mapping unit, See page/paragraph Stormwater Checklist DOE 2005 Manuat.doc Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist _✓c. Erodibility, See page/paragraph IDt a,....o.o,A� 1y"ort Apnw.ouc-A,, _✓d. Settleability, See page/paragraph AHAF ✓e. Permeability, See page/paragraph _<AFi E L/f. Depth, See page/paragraph 's L'g. Texture, See page/paragraph SWf V h. Soil Structure, See page/paragraph 64HE 7. Erosion Problem Areas ✓Description of potential erosion problems on site. See page/paragraph 8. Construction Phasing _✓a. Construction sequence, See page/paragraph 1 6 Z. ✓b. Construction phasing (if proposed) , See page/paragraph 161Z 9. Construction Schedule ✓I. Provide a proposed construction schedule, See page/paragraph /6�2 ✓ II. Wet Season Construction Activities _✓ a. Proposed wet season construction activities, See page/paragraph 16 Z _✓b. Proposed wet season construction restraints for environmentally sensitive/critical areas. See page/paragraph 161z 41 10. Engineering Calculations 1. Provide Design Calculations. ✓ a. Sediment Ponds/Traps, See page/paragraph NIA ✓ b. Diversions, See page/paragraph AJ4A V. c. Waterways, See page/paragraph QA v"' d. Runoff/Stormwater Detention Calculations, See page/paragraph r�l' 11. Operations and Maintenance. +�a. An operation and maintenance schedule shall be provided for all proposed stormwater facilities and BMPs, and the party (or parties) responsible for maintenance and operation shall be identified. An operation and maintenance (OEtM) Declaration of Covenant will be required to cover all privately owned and maintained stormwater facilities. OEtM Declaration of Covenant forms are available at the Mason County Permit Assistance Center, 426 W. Cedar Street, Shelton, WA 98584. The proponent shall record a copy of the completed Declaration with the Mason County Auditors' office. A copy of the recorded document must be submitted to the Permit Assistance Center together with this completed Checklist. See page/paragraph AJJA Stormwater Checklist DOE 2005 Manual.doc 3 Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist Section II - Erosion and Sediment Control Plans 1. General a. Vicinity Map, See page/paragraph Aivrm& 3 _ b. Clearing and Grading Approval Block, See page/paragraph W c. Erosion and Sediment Control Notes, See page/paragraph 4g m&y 6 Cl e4 64 And CWPPP 2. Site Plan a. Legal description of subject property _ b. North Arrow c. Indicate boundaries of existing vegetations, e.g. tree lines, pasture areas, etc. _ d. Identify and label areas of potential erosion problems, See page/paragraph N/q e. Identify any on-site or adjacent surface waters, critical areas and associated buffers f. Identify FEMA base flood boundaries and Shoreline Management boundaries (if applicable), See page/paragraph WA g. Show existing and proposed contours h. Indicate drainage basins and direction of flow for individual drainage areas i. Label final grade contours and identify developed condition drainage basins _ j. Delineate areas that are to be cleared and graded k. Show all cut and fill slopes indicating top and bottom of slope catch lines 3. Conveyance Systems a. Designate locations for swales, interceptor trenches, or ditches b. Show all temporary and permanent drainage pipes, ditches, or cut-off trenches Required for erosion and sediment control _ c. Provide minimum slope and cover for all temporary pipes or call out pipe inverts _ d. Show grades, dimensions, and direction of flow in all ditches, swales, culverts, and pipes e. Provide details for bypassing off-site runoff around disturbed areas f. Indicate locations and outlets of any dewatering systems 4. Location of Detention BMPs _ a. Identify location of detention BMPs. 5. Erosion and Sediment Control Facilities a. Show the locations of sediment trap(s), pond(s), and pipe structures. b. Dimension pond berm widths and inside and outside pond slopes. c. Indicate the trap/pond storage required and the depth, length, and width dimensions. _ d. Provide typical section views through pond and outlet structure. e. Provide typical details of gravel cone and standpipe, and/or other filtering devices. f. Detail stabilization techniques for outlet/inlet. g. Detail control/ restrictor device location and details. Stormwater Checklist DOE 2005 Manual.doc 4 Updated May 20, 2009 Mason County Construction Stormwater Pollution Prevention Plan Checklist h. Specify mulch and/or recommended cover of berms and slopes. _ i. Provide rock specifications and detail for rock check dams. j. Specify spacing for rock check dams as required. k. Provide front and side sections of typical rock check dams. 1. Indicate the locations and provide details and specifications for silt fabric. m. Locate the construction entrance and provide a detail. 6. Detailed Drawings a. Any structural practices used that are not referenced in the Ecology Manual should be explained and illustrated with detailed drawings. 7. Other Pollutant BMPs a. Indicate on the site plan the location of BMPs to be used for the control of pollutants other than sediment, e.g. concrete wash water. 8. Monitoring Locations a. Indicate on the site plan the water quality sampling locations to be used for monitoring water quality on the construction site, if applicable. I certify that the stormwater plan submitted for this project fulfills the applicable provisions of the 2005 DOE Stormwater Manual. a �oF wAsy�ticc9IAT 13 Engineer Date ,r �39390 SIONAL ` Applicant Date Place signed stamp here Stormwater Checklist DOE 2005 Manual.doc 5 Updated May 20, 2009