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HomeMy WebLinkAboutGEO2012-00056 - GEO Geological Review - 11/19/2015MASON COUNTY DEPARTMENT OF COMMUNITY DEVELOPMENT Planning Division P O Box 279, Shelton, WA 98584 (360)427-9670 Geotechnical ReportReview Acceptance Letter November 06, 2015 DEAN ELLIOT 2534 GRAYSBY AVE SAN PEFRO CA 90732 Case No.: GEO2012-00056 Parcel No.: 221224300080 Project Description: GEO REPORT COMPLETED AND SUBMITTED FOR FUTURE CONSTRUCTION OF SFR The Geotechnical Report for DEAN ELLIOT has been received and reviewed by the Planning Department. The report was prepared by Michael Staten PE 43045 dated 10/25/2012. Based on the certification provided by the licensed engineer/geologist, the referenced Geotechnical Report was prepared in general accordance with the requirements in the Mason County Resource Ordinance, Landslide Hazard Areas 17.01.100.E.5. Mason County considers the review valid until such time as scope of project, site conditions, and/or regulations change. Should the scope of work, site conditions, and/or regulations change after the original review, then an addendum from the original author of the report may be required to address these changes, The report would only be re -reviewed if a permit for development were submitted after these changes occur. Mason County does not certify the quality of the work done in this Geotechnical Report. Please contact me at (360) 427-9670, ext. 365 if you have questions. Sincerely, Allan Borden Land Use Planner Mason County Planning Department Comments: 11/6/2015 Page 1 of 1 GEO2012-00056 (7) Mason County Department of Community Deveiopmont ckiist For a Geotechnical Report instructions: This checklist must be submitted with a Geotechrrieal Report and completed, signed, and stamped by the licensed professional(s) who prepared the Geotechnical Report for review by Mason County pursuant to the Mason County Resource Ordinance. Wan; item found to be not applicable, the report should explain the basis for the conclusion- Applicant/Owner Dpaike, Site Address X XX I /5/ ► -UI e.t.a (1) Parcel # 221 ZZ -q-3-Q©©ge7 cu( / (mr20-v, ,J, (,'v7A (a) A discussion of general gpolagic conditions in the vicinity of the proposed development, Located on page(s) (b) A discussion of specific slit types Located on page(s) 6 (c) A discussion of ground water conditions Located on page(s) 7 (d) A discussion of the upslope geomorphology Loc aied on page(s) 3 (a) A discussion of the location of upland waterbodies and wetlands Located on page(s) �- ) A discussion of history of landslide activity in the activity in the vicinity, as available in the referenced maps and records Located or, page(s; , 9 (2) A site plan which identifies (he rrrperfant development and geologic features, Located on Map(s) (3) Locations and logs of exploratory holes or probes. Located on Maps) S;+c= Pawn °I /may (�4Pp.9 (4) The area of the proposed development, the boundaries of the hazard, and associated -buffers and setbacks shall be delineated (top-, ipoth sides, and toe) on 1 -geologic map of the site. Located on Map(s)6; Plan (5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which incorporates the details of proposed grade changes. Located on Map(s) So , / (79p . (6) A. description and results of slope stability arfalyses performed forbo : static and seismic nadir conditions. Analysis should examine worst case -failures. The analysis should include the Simplified Bishop's Method of C tes_ The minimum static safety factor is 1.5, the minimum Simplified Bishop'_ seismic safety factor is 1.1_ and the quasi-sta€ic analysis contents should be a value of 0.15. Located on page(s) /0 a G (a) Appropriate restrictions an placement of drainage features Located on page(s) / Ai /9 (b) Appropriate restrictions on placement of septic drain yields Located on page(s) 2O (c) .Appropriate restrictions on placement or compacted fills and footings Located on page(s) /9 . / 6, / 7 Page 1 of 2 Disclaimer: Mason County does not certify Form Effective June 2008 done in this Geotcchnicrl Report. (d) Recommended buffers from the landslide hazard areas shoreline' bluffs and the tops of other slopes on the property. Located on page(s) / 9 (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes on the property. Located on page(s) I (8) ttecommendations for the preparation of a detailed clearing and ing pier; vlF tic eper ir8txaily identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation removal. Located on page(s) / 9 (9) 1. Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific mitigating measures to be implemented during construction to protect the slope from erosion, landslides and harmful construction methods. Located on page(s) An analysis of both on -site and off -site impacts of the proposed development. Located on page(s) 13 Specifications of final development conditions such as, vegetative management, drainage, erosion control, and buffer widths. Located on page(s) /5, 19, 2© - Recommendations for the preparation of structural mitigation or details of other proposed mitigation. Located on page(s) 2-0 A site map drawn to scale showing the property. Dundaries, scale, -north arm", and the location and nature of existing and .proposed development on the site, Lusted on Map(s) ' eon 6-yg, 544, perjury that i am a civil engineer licensed in the State of geotechniicaifgeologimi enginc: , of g or a geologist or en Wag.'aaaa=.z 5=' 7! ` i=y_:3--'s=_ _=-_ :u:l =ge of the Report, dated Oo--/— 2-5, 2a/L, and entitled er,in Eih©f County Resource 0 ce, Landsilde Hazard Section. demonstrates conclusively that the risks posed by the landsii included geoiectinisai design a eeAnaaaaeeaiueiions, aiiieea i,aai to prevent .-3e7_. to property and publichealth ass ,. Page 2 of 2 Disclaimer: Mason Form Effective June 2008 s not cerL 7 trhe quality of the work done In this f3eotechnicaf Report Geotechnical Report for Dean Elliot Single Fa ily esidential Property E Island View oad, Grapeview Parcel No. 22122-43-00080 ason County, ashington October 25, 2012 Project#12101 Prepared For: Dean Elliot 2534 Graysby Avenue San Pedro, California 90732 Prepared By: Envirotech Engineering PO Box 984 Belfair, Washington 98528 Phone: 360-275-9374 Fax: 360-275-4789 TABLE OF CONTENTS 1.0 INTRODUCTION 1 1.1 PROJECT INFORMATION 1 1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK 2 2.0 SURFACE CONDITIONS 3 2.1 GENERAL OBSERVATIONS 3 2.2 TOPOGRAPHY 3 2.2.1 Upslope Geomorphology 3 2.3 SURFACE DRAINAGE 3 2.3.1 Upslope Water Bodies 4 2.4 SLOPE AND EROSION OBSERVATIONS 4 3.0 SUBSURFACE INVESTIGATION 5 3.1 FIELD METHODS, SAMPLING AND FIELD TESTING 5 3.2 GENERAL GEOLOGIC CONDITIONS 5 3.3 SPECIFIC SUBSURFACE CONDITIONS 6 3.3.1 Groundwater 7 4.0 ENGINEERING ANALYSES AND CONCLUSIONS 8 4.1 SLOPE STABILITY 8 4.1.1 Slope Stability Analysis 10 4.1.2 Slope Stability Assessment 11 4.2 EROSION I I 4.2.1 Shoreline Recession 12 4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION 12 4.3.1 Liquefaction 12 4.4 LATERAL EARTH PRESSURES 13 4.5 ON -SITE AND OFF -SITE IMPACTS 13 5.0 ENGINEERING RECOMMENDATIONS 14 5.1 BUILDING FOUNDATION RECOMMENDATIONS 14 5.1.1 Bearing Capacity 14 5.1.2 Settlement 15 5.1.3 Concrete Slabs -on -Grade 15 5.2 EARTHWORK CONSTRUCTION RECOMMENDATIONS 15 5.2.1 Excavation 15 5.2.2 Placement and Compaction of Native Soils and Engineered Fill 16 5.2.3 Retaining Wall Backfill /7 5.2.4 Wet Weather Considerations 17 5.2.5 Building Pads 18 5.3 BUILDING AND FOOTING SETBACKS 18 5.4 SURFACE AND SUBSURFACE DRAINAGE 18 5.4.1 Revetment 19 5.5 VEGETATION BUFFER AND CONSIDERATIONS 19 5.6 TEMPORARY AND PERMANENT EROSION CONTROL 19 5.7 SEPTIC DRAINFIELDS 20 5.8 STRUCTURAL MITIGATION 20 6.0 CLOSURE 21 Appendix A - Site Plan Appendix B - Soil Information (Soil Profile; Soil Logs; Well Reports) Appendix C - Slope Stability Input & Output Appendix D — Erosion Control 1.0 INTRODUCTION Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a single family residential property located along E Island View Road, identified as parcel number 22122- 43-00080, Grapeview, Mason County, Washington. See the vicinity map on the following page for a general depiction of the site location. The geotechnical investigation was conducted at the request of the proponent of the property, Dean Elliot, in support of the proposed development as detailed below. The proposed development, as provided herein, and the surrounding area is identified in this report as the Project. An initial geotechnical evaluation of the Project was conducted by Envirotech on October 19, 2012. It was determined that slopes in excess of 40% with a vertical relief of at least 10 feet were present within 300 feet of the planned development. Based on this site characteristic, the proposed development will require a geotechnical report pursuant to Landslide Hazard Areas of Mason County Resource Ordinance (MCRO) 17.01.100. During the site visit by Envirotech, surface and subsurface conditions were assessed. After completion of the field work and applicable Project research, Envirotech prepared this geotechnical report which, at a minimum, conforms to the applicable MCRO. As presented herein, this report includes information pertaining to the Project in this Introduction Section; observations of the property and surrounding terrain in the Surface Conditions Section; field methods and soil descriptions in the Subsurface Investigation Section; supporting documentation with relation to slope stability, erosion, seismic considerations, and lateral earth pressures in the Engineering Analyses and Conclusions Section; and, recommendations for foundation, settlement, earthwork construction, retaining walls, erosion control, drainage, and vegetation in the Engineering Recommendations Section. 1.1 Project Information Information pertaining to the planned development of the Project was provided by the proponent of the property during the geotechnical investigation. Other Project information was obtained by Envirotech. Existing development consists of a gravel surfaced driveway, drainage facilities, and uninhabitable structures. The immediate planned development consists of a 1 -story dwelling unit, on -site septic system, and other ancillary features typical of this type of development. Future development may consist of a 1- or 2 -story residence. Foundation construction is expected to consist of continuous strip footings with concrete slabs -on -grade or stem walls. Approximate building footprint and other proposed features with relation to existing site conditions are illustrated on the Site Map provided in Appendix A of this report. Envirotech Engineering PO Box 984 Bellair, Washington 98528 Ph. 360-275-9374 Fax: 360-275-4789 page D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-00080 Mason County, Washington October 25. 20 12 1.2 Purpose of Investigation and Scope of Work The purpose of this geotechnical investigation is to assess geological hazards, and evaluate the Project in order to provide geotechnical recommendations that should be implemented during development. The investigation included characterizing the general Project surface and subsurface conditions, and evaluating the suitability of the soils to support the planned site activities. In order to fulfill the purpose of investigation, the geotechnical program completed for the proposed improvements of the Project include: • Review project info' 'nation provided by the Project owner and/ or owner's representative; • Conduct a site visit to document the site conditions that may influence the construction and performance of the proposed improvements of the Project; • Define general subsurface conditions of the site by observing subsoils within test pits and/ or cut banks, review geological maps for the general area, research published references concerning slope stability, and review water well reports from existing wells near the Project; • Collect bulk samples at various depths and locations; • Perform soils testing to determine selected index and/or engineering properties of the site soils; • Complete an engineering analysis supported by the planned site alterations, and the surface and subsurface conditions that were identified by the field investigation, soil testing, and applicable project research; and, • Establish conclusions based on findings, and make recommendations for foundations, drainage, slope stability, erosion control, earthwork construction requirements, and other considerations. E KEYHOLE CT - Z w U KRA©RENHOFT RD Vicinity Map from Mason County Web.site a O cat t ec lecl���ic €l Report F Island ttieo Rood Parcel 22 122-43-00080 r Fox: 3(i0-'75-4789 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the Project was gathered on October 19, 2012 by Michael Staten, geotechnical engineer with Envirotech. During the site visit, the type of geotechnical investigation was assessed, site features were documented that may influence construction, and site features were examined that may be influenced by construction. This Surface Conditions Section provides information on general observations, vegetation, topography, drainage and observed slope/ erosion conditions for the Project and surrounding areas that may impact the Project. 2.1 General Observations The property is accessed from E. Island View Road, an existing paved roadway. The Project is currently partially developed land as previously mentioned. The access road extends along the northern boundary of the parcel, and Pickering Passage borders the property to the south. The property is mostly cleared, and has a natural drainage swale that extends from approximately the northeast corner to the southwest corner of the parcel. Most of the drainage alignment consists of a 24 inch steel drainage pipe with flowing water that has an outlet on the neighboring property into Pickering Passage. Beyond the property, rural residential development exists. Vegetation on and near the Project consists primarily of secondary growth firs, maples, and other trees and shrubbery common to this area of the Pacific Northwest. An aerial photo of the Project and immediate vicinity is provided on the following page. 2.2 Topography The topographic information provided in this section was extrapolated from a public lidar source, and incorporated observations and field measurements. Where necessary, slope verification included measuring slope lengths and inclinations with a cloth tape and inclinometer. See the Site Plan in Appendix A in this report for an illustration of general topography with respect to the planned development. Critical descending slopes, with grades exceeding 40%, are located along the shoreline. The maximum critical slope is nearly vertical with various vertical reliefs along the shoreline, primarily less than 30 feet. Ascending grades are generally located to the northwest of the planned development beyond the natural drainage swale. These slopes are relatively minor within 300 feet of the Project, with apparent slope grades of not much more than 15%. 2.2.1 Upslope Geomorphology The upland area of the property is primarily situated on a hillside of glacial and post glacial origin. 2.3 Surface Drainage Stormwater runoff originating upslope from the anticipated development appears to be channeled onto the property, and is expected to be extreme during high intensity storm events. Runoff Envirotech Engineering PO Box 984 Belfair, Washington 98528 Ph. 360-275-9374 Fax: 360-275-4789 D. Elliot Geotechnical Report E Island Vies- Road Parcel 22122-43-00080 1t�ason County, Washington October 25, 20 12 entering the property is primarily mitigated through a 24 -inch diameter steel pipeline with an outlet at Pickering Passage, as previously mentioned. This drainage pipe appears to collect water from multiple culverts near Island View Road. Clogging of the pipe entrances or insufficient capacity at the pipe inlets can be expected, and overflow will follow the natural drainage swale through the property. Excessive scour was not observed near the location of the planned development. 2.3.1 Upslope Water Bodies There are apparent water bodies or wetlands located upslope from the planned development. Most of the upland watershed appears to bypass the property to the west, and distribute runoff into Pickering Passage. However, the constant surface runoff and minor seepage observed on the lower shoreline bank near the southeast property corner may originate from water bodies. 2.4 Slope and Erosion Observations The slope grades near the Project signal a potential landslide or erosion hazard area. Some indicators that may suggest past slope movements include: • Outwash of sediments near the bottom of the slope, • Fissures, tension cracks, hummocky ground or stepped land masses on the face or top of the slope, and parallel to the slope, • Fine, saturated subsurface soils, • Old landslide debris, • Significant bowing or leaning trees, or, • Slope sloughing or calving. The shoreline bank exhibits slow, continuous erosion such as scarps near the top of bank, exposed soils, vertical banks, and undercutting the slope toe from wave action. Upland areas of the property did not have indications of past landslides, current unstable slopes, deep-seated slope problems, or surficial slope failures at the time of our site visit. See Section 4.1 of this report for a complete slope stability analysis and assessment. Aerial Photo fro ason County Website Euvirotech Engineering Pty Box 984 Bellidir. Washington 985_28 Ph. 360-275-9374 f az: 360-275-4789 page 4 D. Elliot Ocotechnical Report E Island View Road Parcel 2212243-00080 Mason County. Washington t?r T25.2012 3.0 SUBSURFACE INVESTIGATION Information on subsurface conditions pertaining to the Project was primarily gathered on October 19, 2012 by Michael Staten, geotechnical engineer with Envirotech. Specific information on field methods, sampling, field testing, general geologic conditions, specific subsurface conditions, and results from soil testing are presented in this section of the report. Appendix B of this report includes pertinent information on subsurface conditions for the Project, such as subsoil cross- section(s), test pit log(s), and water well report(s). Water well reports were utilized to estimate ground water levels, and if sufficient, were used in identifying subsoil types. Additional well reports than what is provided in this report may be available from Envirotech upon request. Applicable test pit locations are depicted on the Site Plan provided in the appendix of this report. 3.1 Field Methods, Sampling and Field Testing Information on subsurface conditions for the Project was accomplished by examining soils within test pits extending to depths of up to 4 feet below the existing ground surface, and observing cut slopes/ shoreline banks of up to 30 feet within the vicinity of the property. Information on subsurface conditions also included reviewing geological maps representing the general vicinity of the project, and water well reports originating from nearby properties. Soil samples were not obtained from this project. Envirotech measured the relative density of the near -surface in -situ soils by gauging the resistance of hand tools. Within testing locations, field testing results generally indicated loose and soft soils in the upper 30 inches, competent bearing soils at 30 inches and below, and very dense soils varying from 30 inches to over 48 inches that extend to the depth of terminous. 3.2 General Geologic Conditions In general, soils at the project are composed of materials from glacial advances. The geologic conditions as presented in the "Geologic Map of Washington," compiled by J. Eric Schuster, 2002 indicates Quaternary sediments, Q. Quaternary sediments are generally unconsolidated deposits, and dominantly deposited from glacial drift, including alluvium deposits. This project is located within the Puget Lowland. Typically, "lower tertiary sedimentary rocks unconformably overlie the Crescent Formation." as revealed in the Geologic Map. Initial sedimentary rocks were formed from shales, sandstones and coal deposits from rivers. During the Quaternary period, the Puget Lowland was covered by numerous ice sheets, with the most recent being the Fraser glacier with a peak of approximately 14,000 years ago. Upon the glacial retreat, the landscape was formed by glacial erosion glacial drift deposits. The "Geologic Map of the Mason Lake 7.5 -minute Quadrangle, Mason County, Washington" by Robert E. Derkey, et al, July 2009, provides the following caption(s) for the project area: Envirotech Engineering PO Box 934 Bellai', Washington 98523 Ph. 360-275-9374 Fax: 360-275-4789 page 5 D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-00080 Mason County, Washineton October 25, 2012 1'1'e-Vahou 11i�ni-'1:1�litl'_1;11wr'�, ,.;1!lt:l. -Iii.:?fl+l Ilt'l+.ticrik-j'1l,"`,CII'fll 1.=`{': _. vvc11, aiY h<<�1'': ;'1. rIceSi6 witr,h' . f 1.7 C11 tor r aucl 3.3 Specific Subsurface Conditions The following subsurface conditions are estimated descriptions of the Project subgrade utilizing information from the depth of penetration at all testing, sampling, observed and investigated locations. Soils for this project were primarily described utilizing the Unified Soil Classification System (USCS) and the Soil Conservation Service (SCS) descriptions. Soils are extremely variable for this project. Fill soils have been reported to be on the property, and may have been encountered within the test pit excavation. Within test pit locations, soils within the upper 4 feet of natural ground were observed to be either moist, brown silty sand with gravel (SM) or clay with sand and silt (CL). Soils below the upper 4 feet layer in most locations to a depth of over 25 feet below the ground surface were observed to be mostly brown and grey, low moisture, silty sand with gravel (SM) or silty clay (CL -ML), locally known as hardpan. The hardpan may extend to depths greater than 50 feet. This is based on nearby well reports, site geology, and/ or knowledge of the general area. However, an isolated area near the building pad may have hardpan depths of greater than 5 feet below the existing ground surface. The relative densities of the soil within selected test pits are provided above in Section 3.1. Expanded and specific subsurface descriptions, other than what is provided in this section, are provided in the soil logs located in Appendix B of this report. According to the "Soil Survey of Mason County," by the United States Department of Agriculture, Soil Conservation Service, the lowland site soils where initial development will mostly occur are described as Kitsap Silt Loam, Kb, with 5% - 15% slopes. The upland site soils are described as Everett Gravelly Sandy Loam, Eh, with 5% - 15% slopes. The shoreline and immediate soils upland from the bank are delineated as Rough Broken Land. The soil designations are depicted in the aerial photograph below, and descriptions are provided in Appendix B of this report. Envirotech Engineering PO Bx 984 13elthir. Washii08523 Ph. 3(10-275-937,4 Fax: 300-275-4730 :3eotechnical Report E Island View Road Parcel 22122-43-00080 Mason County, Washin,ton October 25. 20 I Soil Survey From USDA Natural Resources Conservation Service 3.3.1 Groundwater From the water well report(s) and knowledge of the general area, permanent groundwater is at least 50 feet directly below the property at the building pad location. Minor groundwater seepage from the lower shoreline bank was observed near the southeast corner of the property. 981 f3elihir. A'ashi98528 Ph, 360-275-9374 Fax: 360-275-478Q prole 7 Parcel 22 12 ?-43-00080 Mason County, \1'a;him_>ton (.)ctoher 25, 21)12 4.0 ENGINEERING ANALYSES AND CONCLUSIONS The following sections present engineering analyses and conclusions with relation to the existing conditions and proposed improvements of the Project. This section includes slope stability, erosion, seismic considerations, lateral earth pressures, and impacts to both on -site and off -site properties. 4.1 Slope Stability Landslides are natural geologic processes, and structures near slopes possess an inherent risk of adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering cannot eliminate these risks for any site with sloping grades because gravity is constantly inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will exacerbate these strains. Wet soils are heavier than dry soils, and reduce both cohesion and the frictional resistance of the soil. Seismic activity also reduces friction, temporarily, and can also move soil particles into a less stable configuration. Geotechnical engineering considers excessive wet weather and `design' earthquakes in order to provide accepted factors of safety for developing on or near sloping terrain with relation to current engineering protocol. These factors of safeties are based on engineering standards such as defining engineering properties of the soil, topography, water conditions, seismic acceleration and surcharges. Surface sloughing or other types of surficial slope movements usually do not affect the deep- seated structural capability of the slope. However, excessive and/or repeated surficial slope movements, if not repaired, may represent a threat to the structural integrity of the slope. If this situation does arise, the slope shall be inspected by a geotechnical engineer. Subsequently, maintenance may be required in order to prevent the possibility of further surficial or deep seated slope movements that may be damaging to life and property. According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and near terrain labeled `Stable' and `Unstable' regarding potential landslide activity. Stable slopes are generally not prone to landslides due to small grades and accommodating geology. Unstable slopes are designated along the shoreline, and are considered unstable because of geology, groundwater, slope and/ or erosional factors. They include areas of landslides and talus too obscure to be individually mapped. A site specific analyses and recommendations concerning the slopes are presented herein. A Stability Map from the Coastal Zone Atlas for the general area of this Project is provided below. F,nvirotech Engineering PO Box 984 I3enir. Washington 98528 Ph. 360-275-9374 Fax: 360-275-4789 D. Elliot Geotechnical Report F Island View Road Parcel 22122-43-00080 Mason County, Washington October 25, 20l2 Map from Washington State Department of Ecology Website According to the Resource Map from the Washington State Department of Natural Resources (DNR), the Project is within terrain labeled `highly unstable' and `highly erodible' relating to soils. This designation is primarily along the shoreline. DNR did not indicate previous landslide activity on the property, but mapped a landslide approximately 200 to 300 feet to the west of the property along the shoreline. A Resource Map from the DNR website for the general area of this Project is provided below: X 84 Belfair. \Vashinuton )5528 Ph. 360 -275 -x)37 -1 Fill: 360-275--47$x) page 9 E Island Viet Road Parcel 22 122-43-00080 Mason County, 'Vasltin eton Resource Map from Washington State Department of Natural Resources Website 4.1.1 Slope Stability Analysis Based on site geology, a non -circular slope stability analysis should be performed. However, the Simplified Bishop Method (circular analysis), as presented herein, was utilized. Although the method of circles does not fit the site conditions, Envirotech certifies that our analysis is more conservative for these project conditions than other conforming slope stability models. For this Project and level of geotechnical investigation, our conclusions or recommendations would not be changed by this variation in analysis. Where applicable, our slope stability analysis utilizes the subsurface angle of repose. The Simplified Bishop Method, utilizing `STABLE' software, was used to analyze the static stability of the site slopes. Seismic conditions were estimated utilizing worst case scenario values from the static analysis, a quasi -static analysis coefficient of at least 0.15, and applying the applicable values to STABLE software. Various radii's and center points of the circle were automatically selected, and produced factor of safeties in a graphical and tabular format. Worst case scenario values were used in the slope stability analysis in regards to topography, surcharges, water content, internal friction and cohesion of the site soils. STABLE software has been repeatedly checked with manual Envirotech En6neerino I'O Box 984 I3elfair, \Vashinoton 985?8 Ph. 360-275-9374 Fax: 360-275-4789 D. Elliot Geotechnleal Report I: . Island View Road Parcel 22 122-43-000S0 Mason County. Washington 20 I calculations, and consistently proved to be a very conservative program. The following soil properties were used in the analysis, and are based on observed conditions, known geology, and/or published parameters: Upper 5 feet soil depth Soil unit weight: Angle of internal friction: Cohesion: Soils below 5 feet in depth Soil unit weight: Angle of internal friction: Cohesion: 128 pcf 15 degrees 100 psf 140 pcf 40 degrees 400 psf Based on the slope stability analysis, a minimum factor of safety was determined to be 0.7 relative to static slope failures, and 0.5 with relation to seismic conditions. These factor of safeties were primarily limited to the face of the slope, and do not reflect conditions where development is expected to occur. For this Project, at the location of the proposed development, minimum factor of safeties for static and dynamic conditions were estimated to be over 1.5 and 1.1, respectively. See the slope stability infonnation in Appendix C for a depiction of input parameters and example of outputs. 4.1.2 Slope Stability Assessment Mapped slope conditions, as delineated by the Departments of Ecology and Natural Resources, were considered in our slope stability assessment. Based on the proximity and severity of mapped delineations with respect to the proposed development, results of the aforesaid slope stability analysis, observed surface conditions, and an evaluation of the shoreline recession rate, it is our opinion that the proposed development should occur in accordance with this geotechnical report. 4.2 Erosion Based on the USCS description of the Project soils, the surface soils are considered moderately to highly erodible. According to the Resource Map from the Washington State DNR, as provided above, the Project is within terrain labeled `highly erodible.' However, this designation is on the property, outside of the area of the planned development. This Project is not within an erosion hazard area as defined by the MCRO. Erosion hazard areas are those with USDA SCS designations of River Wash (Ra), Coastal Beaches (Cg), Alderwood Gravelly Sandy Loam on slopes 15% or greater (Ac and Ad), Cloquallum Silt Loam on slopes 15% or greater (Cd), Harstine Gravelly Sandy Loam on slopes 15% or greater (lib), and Kitsap Silt Loam on slopes 15% or greater (Kc). It is our opinion that minor erosion control recommendations provided in this report is sufficient for the development of this Project, and additional erosion control plans are not required. Temporary and permanent erosion control measures are required for site development. Extents of Envirotech Engineering PO Box 984 Belfair. Washington 98528 Ph. 360-275-9374 Fax: 360-275-4789 page II D. Elliot Geoteclinical Report E Island View Road Parcel 22122-43-00080 Mason County. Washington October 25. 2012 temporary erosion control will mostly depend on the timeliness of construction, moisture content of the soil, and amount of rainfall during construction. Soil erosion typical to the existing site conditions and planned disturbance of the Project include wind-borne silts during dry weather, and sediment transport during prolonged wet weather. Sediment transport could be from stormwater runoff or tracking off -site with construction equipment. The Temporary and Permanent Erosion Control Section (Section 5.6) of this report consist of specific erosion controls to be implemented. Additional erosion control information and specifications may be found in the latest addition of the "Stormwater Management Manual for Western Washington," prepared by the Washington State Depa►tinent of Ecology Water Quality Program. 4.2.1 Shoreline Recession Due to the close proximity of a shoreline, an evaluation of the shoreline recession rate for this Project was completed. This was accomplished by carefully reviewing and comparing aerial photographs of the Project from several sources. Some of these sources include a 1951 aerial for the Soil Survey of Mason County, 2006 aerial from the Washington State Department of Ecology, and various shoreline photographs from the Washington State Department of Natural Resources. In addition, owner reports of the shoreline conditions for over a 20 year span was considered. Based on available information, we conclude that the past shoreline recession for this Project is less than 10 feet in 50 years. 4.3 Seismic Considerations and Liquefaction Soils immediately below the expected foundation depth for this Project are generally Type E, corresponding to the International Building Code (IBC) soil profiles. According to the IBC, the regional seismic zone is 3 for this Project. The estimated peak ground acceleration ranges from 0.50g to 0.60g. This estimation is based on the United States Geological Survey (USGS) National Seismic Hazard Project in which there is an estimated 2% probability of exceedance within the next 50 years. There are no known faults beneath this Project. The nearest Class 'A' or Class `B' fault to this property is the Tacoma Fault Zone, in which is approximately 6.5 miles to the north of this Project. This information is based on the USGS Quaternary Fault and Fold Database for the United States. 4.3.1 Liquefaction The potential for liquefaction is believed to be low for this Project. This is based, in part, on the subsurface conditions such as soil characteristics and the lack of a permanent shallow water table. Subgrade characteristics that particularly contribute to problems caused from liquefaction include submerged, confined, poorly -graded granular soils (i.e. gravel, sand, silt). Although gravel- and silt -sized soil particles could be problematic, fine and medium grained sands are typically subjected to these types of seismic hazards. No significant saturated sand stratifications are anticipated to be within the upper 50 feet of the subsoil for this Project. Envirotech Eno ineering PO Box 984 Belfair. Washington 98528 Ph, 360-275-9374 Fax: 360-275-4789 page 12 D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-00080 Mason Count}, Washington October 25, 2012 4.4 Lateral Earth Pressures Retaining walls may be utilized for this Project. The lateral earth pressures exerted through the backfill of a retaining wall are dependent upon several factors including height of retained soil behind the wall, type of soil that is retained, degree of backfill compaction, slope of backfill, surcharges, hydrostatic pressures, earthquake pressures, and the direction and distance that the top of the wall moves. A structural or geotechnical professional should design retaining walls based on specific conditions. Soil parameters for the structural design of retaining walls may be estimated as 134 pounds per cubic foot (pcf) for engineered fill. Native soils are not recommended for retaining wall backfill for this project. The angle of internal friction may be estimated as 36 degrees for engineered fill. These soil parameters are based on soil type and placement conforming to the Earthwork Construction Recommendations Section in this report. 43 On -Site and Off -Site Impacts From a geotechnical position, it is Envirotech's opinion that the subject property and adjacent properties to the proposed development should not be significantly impacted if all recommendations in this report are followed. This opinion is based on the expected site development, existing topography, existing nearby development, land cover, and adhering to the recommendations presented in this report. Future development or land disturbing activities on neighboring properties or properties beyond adjacent parcels that are upslope and/or downslope from the subject property could cause problems to the subject property. For this reason, future development or land disturbance near the subject property should be evaluated by a geotechnical engineer. Envirotech Engineering PO Box 984 Beltair. Washington 98528 Ph. 360-275-9374 Fa.\: 360-275-4789 D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-0008(1 Mason County. Washington October 25.201 5.0 ENGINEERING RECOMMENDATIONS The following sections present engineering recommendations for the proposed improvements of the Project. These recommendations have been made available based on the planned improvements as outlined in the Introduction Section of this report; general observations including drainage and topography as recapitulated in the Surface Conditions Section; soil/ geologic conditions that were identified from the geotechnical investigation that is summarized in the Subsurface Investigation Section; and, Project research, analyses and conclusions as determined in the Engineering Analysis and Conclusions Section. Recommendations for the Project that is provided herein, includes pertinent information for building foundations, earthwork construction, building and/ or footing setbacks, drainage, vegetation considerations, and erosion control. 5.1 Building Foundation Recommendations Recommendations provided in this section account for the site development of a typical one- or two-story, single family residential structure. The recommended allowable bearing capacities and settlements as presented below, consider the probable type of construction as well as the field investigation results by implementing practical engineering judgment within published engineering standards. Evaluations include classifying site soils based on observed field conditions and soil testing for this Project. After deriving conservative relative densities, unit weights and angles of internal friction of the in -situ soils, the Terzhagi ultimate bearing capacity equation was utilized for determining foundation width and depth. Foundation parameters provided herein account for typical structural pressures due to the planned type of development. A structural analysis is beyond the scope of a geotechnical report, and a structural engineer may be required to design specific foundations and other structural elements based on the soil investigation. Stepped foundations are acceptable, if warranted for this Project. Continuous, isolated, or stepped foundations shall be horizontally level between the bottom of the foundation and the top of the bearing strata. The frost penetration depth is not expected to extend beyond 12 inches below the ground surface for this Project under normal circumstances and anticipated design features. 5.1.1 Bearing Capacity Existing in -situ soils for this Project indicates that the structure can be established on shallow, continuous or isolated footings. Foundations shall be established on relatively undisturbed native soil. Alternatively, foundations may be constructed on selective re - compacted native soil or compacted engineered fill as described in the Earthwork Construction Recommendations Section of this report. For a bearing capacity requirement of no more than 1500 psf, a minimum continuous footing width of 20 inches shall be placed at a minimum of 30 inches below the existing ground surface. For a columnar load of no more than 2 tons, a circular or square isolated foundation diameter or width shall be at least 24 inches. Foundation recommendations are made available based on adherence to the remaining recommendations that are provided in this report. Alterations to the aforementioned foundation recommendations Envirotech Engineering PO Box 984 Bel Fair, Washintlton 98528 Ph. 360-275-9374 Fax: 360-275-4789 4 D. Elliot Geotechnical Report E Island View Road Parcel 2212)-43-00080 Mason County. Washington October 25. 20 12 may be completed upon a site inspection by a geotechnical engineer after the foundation excavation is completed. 5.1.2 Settlement Total and differential settlement that a structure will undergo depends primarily on the subsurface conditions, type of structure, amount and duration of pressure exerted by the structure, reduction of pore water pressure, and in some instances, the infiltration of free moisture. Based on the expected native soil conditions, anticipated development, and construction abides by the recommendations in this report, the assumed foundation system may undergo a maximum of 1.0 inch total settlement, and a maximum differential settlement of 0.75 inch. 5.1.3 Concrete Slabs -on -Grade Interior slabs, if utilized, should be supported on a minimum of 4 inches of compacted coarse, granular material (Passing U.S. Sieve #10 or greater) that is placed over undisturbed, competent native subgrade or engineered fill. Native soils found at the Project site may be suitable for use as material directly beneath concrete slabs if it meets the aforesaid requirements or screened to meet these requirements. The upper organic laden native soil should be removed prior to the placement and compaction of the aforementioned 4 -inch coarse, granular material. The recommendations for interior concrete slabs -on -grade as presented herein are only relevant for the geotechnical application of this Project. Although beyond the scope of geotechnical engineering, concrete slabs should also be designed for structural integrity and environmental reliability. This may include some type of vapor barrier or moisture control for mitigating excessive moisture in the building. 5.2 Earthwork Construction Recommendations Founding material for building foundations shall consist of undisturbed native soils to the specified foundation depths. Compacted engineered fill, or selective re -compacted native soils may be used to the extents provided in this Earthwork Construction Recommendations Section. The following recommendations include excavations, subgrade preparation, type of fill, and placement of fill for building foundations. 5.2.1 Excavation From a geotechnical standpoint, excavation is not restricted for this project, and may encroach the building setbacks as provided in this report. Excavation is recommended to remove any excessive organic content or other deleterious material, if present, beneath foundations and to achieve appropriate foundation depth. Additional sub -excavation will be required for this Project if the soils below the required foundation depth are loose, saturated, not as described in this report, or otherwise incompetent due to inappropriate land disturbing, or excessive water trapped within foundation excavations prior to foundation construction. All soils below the bottom of the excavation shall be competent, and relatively undisturbed or properly compacted fill. If these soils are disturbed or Env irotech Engineering PO Box 984 Beltair, Washineton 98528 Ph. 360-275-9374 Fax: 360-275-4789 page I5 D. Elliot Geotechnical Report E Island View Road Parcel 221 22-43-00080 Mason County, Washington October 25, 2012 deemed incompetent, re -compaction of these soils below the anticipated footing depth is necessary. Excavations shall be completely dewatered, compacted, and suitable before placement of additional native soil, engineered fill or structural concrete. 5.2.2 Placement and Compaction of Native Soils and Engineered Fill For engineered fill or disturbed native soils that will be utilized as fill material directly beneath foundations, observation and/ or geotechnical testing is required prior to foundation construction. The following placement and compaction requirements are necessary. For disturbed native soils or engineered fill beneath foundations, limits of compacted or re -compacted fill shall extend laterally from the bottom edge of the foundation at a rate of one horizontal foot for each foot of compacted or re -compacted fill depth beneath the foundation. See the illustration below. COMPACTED NATIVE SOILS DR ENGINEERED FILL II II UNDISTURBED SUBGRADE --FOOTING ,rl Significant fill (fill depth exceeding 12 inches) should not be placed within the building setbacks. Due to the moisture sensitivity, native soils used as compacted fill may be less economical than importing structural fill. However, with careful conditioning and placement, native soils may be used. Both engineered fill and native soils used as compacted fill should be free of roots and other organics, rocks over 6 inches in size, or any other deleterious matter. Engineered fill shall include having the soils retained on the No. 4 sieve crushed (angular), and should consist of the following gradation: U.S. Standard Sieve 6" 3" No. 4 No. 200 % Finer (by weight) 100 60 — 100 20-60 0-8 Table 1 Partical Size Distribution of Engineered Fill Compaction shall be achieved in compacted lifts not to exceed 6 inches for both native soils and engineered fill, respectively. Each lift should be uniformly compacted to at least 90% of the modified Proctor maximum dry density (ASTM D 1557) and within 3% of optimum moisture content. Each lift surface should be adequately maintained during construction in order to achieve acceptable compaction and inter -lift bonding. If the native clayey soils have a high moisture content when construction is ready to begin, the soils will need to be excavated into rows, and frequently disturbed during dry weather in Envirotech Engineering PO Box 98.4 Belltur. Washiiwton 98528 Ph. 360-275-9374 Fax: 360-275-4789 page 16 D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-00080 Mason County, Washington October 25. 2012 order to achieve optimal moisture content. In order to achieve compliance, sheeps foot or pneumatic rollers work best for compacting these types of soils. Temporary earth cuts and temporary fill slopes exceeding 4 feet in height should be limited to a slope of 2:1 (horizontal:vertical). Utility trenches or other confined excavations exceeding 4 feet should conform to OSHA safety regulations. Permanent cut and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an engineer. 5.2.3 Retaining Wall Backfill Native soils may not be used as retaining wall backfill for this Project. Backfill should consist of engineered fill, as presented in this report, or borrow material approved by a geotechnical engineer. Compaction of these materials shall be achieved in compacted lifts of about 12 inches. Each lift should be uniformly compacted to at least 85%, and no more than 90% of the modified Proctor maximum dry density (ASTM D 1557). In addition, heavy construction equipment should be at a distance of at least %z the wall height. Over - compaction and limiting heavy construction equipment should be prevented to minimize the risk of excess lateral earth pressure on the retaining structure. Envirotech recommends that retaining wall backfill is compacted with light equipment such as a hand-held power tamper. If clean, coarse gravel soils are utilized as engineered fill, and surcharges will not influence the retaining wall, compaction may be achieved by reasonably densifying granular soils with construction equipment. Backfill for the retaining wall should extend vertically from the top of the footing to the proposed ground surface. The backfill should also extend horizontally from the back of the retaining wall to at least 2 feet. Perforated drain pipe for retaining walls should have a minimum diameter of 4 inches and direct water to an appropriate infiltration or outfall as recommended in the Surface and Subsurface Drainage Section of this report. Coarse, clean gravel (1 inch diameter) is recommended to be placed at least 24 inches around the drain pipe in order to provide increased drainage capabilities. Non -woven geotextile filter fabric designed to impede fine particles should be wrapped around the aforementioned coarse gravel for reducing the potential of silt migration and clogging of the drain pipe. See the diagram below: FT HI'; IF ;ECE`•". R4-KFILL t7`,'E'. ,E©TF ?' :LE I', 'ri =''.HE II I. -?.IN PO' #: 4 I"I Uh, -E"FDL=TEL -17r- 5.2.4 Wet Weather Considerations Due to the types of subsurface soils, additional provisions may be required during prolonged wet weather. Every precaution should be made in order to prevent free Envirotech Engineering PO Box 984 Beltair. Washington 98528 Ph. .360-275-9371 Fax: 360-275-4789 page 17 D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-00080 Mason County. Wasllinoton October 25. 2012 moisture from saturating the soils within excavations. If the bottom of excavations used for footing placement changes from a moist and dense/ hard characteristic as presented in this report to muck or soft, saturated conditions, then these soils become unsuitable for foundation bearing material. If this situation occurs, a geotechnical engineer should be notified, and these soils should be completely removed and replaced with compacted engineered fill or suitable native material as presented in this section. The types of native soils for this project are moisture sensitive, and should not be worked during the wet season. Ground improvement, such as ballast or other structural fill, may be warranted for this project at any time of the year. 5.2.5 Building Pads Building pads for this Project, shall be constructed per the fill placement and compaction recommendations as presented above. Both engineered fill and native soils may be used for building pads. See the recommendations above for native soils used as compacted fill. Building pad slopes shall be no steeper than 2:1 for both compacted engineered fill and re -compacted native soils used as fill. Building pad fill shall be "keyed" into the existing subgrade to a depth of at least 2 feet below the existing ground surface. The term "keyed," as used here, implies that the interface between the building pad and subgrade is horizontally level. Stepped fill should be keyed into the subgrade at a minimum width of 10 feet. All footings shall be located at least 5 feet away from the top of the engineered fill slope. 5.3 Building and Footing Setbacks Provided that assumptions relating to construction occur and recommendations are followed as presented in this report, the factor of safety for slope stability is sufficient for a 50 feet footing setback from the face of the nearby descending shoreline slopes exceeding 40%. See the figure below and the Site Plan in Appendix A for an illustration of the setbacks. STRUCTURE FOOTING 5.4 Surface and Subsurface Drainage Positive drainage should be provided in the final design for all planned residential buildings. Drainage shall include sloping the ground surface, driveways and sidewalks away from the Project structures. All constructed surface and subsurface drains should be adequately maintained during the life of the structure. If drainage problems occur during or after construction, additional engineered water mitigation will be required immediately. This may include a combination of swales, berms, drain pipes, infiltration facilities, or outlet protection in order to divert water away Envirotech Engineering PO Box 984 Beltair. Washington 98523 Ph. 360-'75.9374 Fax: 360-275-4789 page 18 U. Elliot (3eotechnical Report E Island View Road Parcel 22122-43-0008( Mason County, Washington Oclober 25, 2012 from the structures to an appropriate protected discharge area. Leakage of water pipes, both drainage and supply lines, shall be prevented at all times. Both footing perimeter drains and roof drains are required for this Project. Subsurface water intercepted in the footing perimeter drains, and stormwater collected from roof drains shall be separately tight -lined to an appropriate infiltration facility located at least 10 feet downslope of the structure, and outside of the building setback. If subsurface infiltration is not utilized, an energy dissipater is required at the outlet. For this project, splash pads at roof downspouts may be utilized for downspouts collecting runoff from no more than 700 sf of roof area. 5.4.1 Revetment Revetment is required for the bypass of possible surface drainage between the proposed fill embankment and the drainage course. It is recommended that revetments are constructed of reinforced concrete walls, rockery of at least 1- to 2 -man rock, or modular blocks of at least 75 pounds. If rock or block is used as revetment, a 12 -inch depth crushed ballast or riprap of 2 to 8 inches in size followed by a filter fabric should be placed directly behind the revetment. The revetment shall extend along the border of the embankment in order to protect the fill. See a general depiction of the existing natural drainage swale and the revetment location in the Site Plan in Appendix A of this report. The top of the wall should exceed the maximum high water elevation, and the embedment depth should be at least 2 feet below the existing grade. For conservative purposes, we estimate that the maximum high water elevation is 6 feet above the bottom of the drainage swale. The revetment should extend for a length necessary in order to meet the elevation requirements. 5.5 Vegetation Buffer and Considerations Vegetation is an excellent measure to minimize surficial slope movements and erosion on slope faces and exposed surfaces. By removing trees, the root strength is decreased over time, thereby lowering the `apparent' cohesion of the soil. Transpiration is decreased, which results in additional groundwater, increased pore water pressure and less cohesion/ friction of the soil particles. Stormwater runoff also increases, and, fewer plants will create less absorption of the force from raindrops, thereby creating the potential for erosion hazards. For this project, we believe that a detailed clearing and grading plan is not warranted, and basic vegetation management practices should be adhered to. Vegetation shall not be removed from the face of the critical slope or within a distance of 10 feet beyond the top of the slope. However, any tree deemed hazardous to life or property shall be removed. If tree removal is necessary, then stumps and roots shall remain in place, and the underbrush and soil shall remain undisturbed as much as possible. Any disturbed soil shall be graded and re -compacted in order to restore the terrain similar to preexisting conditions and drainage patterns. See the Site Plan in Appendix A of this report for a depiction of the vegetation buffer. 5.6 Temporary and Permanent Erosion Control Erosion control measures during construction may include stockpiling cleared vegetation, silt fencing, intercepting swales, benns, straw bales, plastic cover or other standard controls. Envirotech Engineering PO Box 984 Bellair, Washington 98528 Ph. 360-275-9374 lax, 360-275-4789 pace 19 D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-00080 Mason County. Washington October 25. 2012 Although other controls may be used, if adequate, silt fencing is presented in this report as the first choice for temporary erosion control. Any erosion control should be located down -slope and beyond the limits of construction and clearing of vegetation where surface water is expected to flow. If the loss of sediments appears to be greater than expected, or erosion control measures are not functioning as needed, additional measures must be implemented immediately. See Appendix D for sketches and general notes regarding selected erosion control measures. The Site Map in Appendix A depicts the recommended locations for erosion control facilities to be installed. Permanent erosion control may also be necessary if substantial vegetation has not been established within disturbed areas upon completion of the Project. Temporary erosion control should remain in place until permanent erosion control has been established. Permanent erosion control may include promoting the growth of vegetation within the exposed areas by mulching, seeding or an equivalent measure. Selected recommendations for permanent erosion control are provided in Appendix D. Additional erosion control measures that should be performed include routine maintenance and replacement, when necessary, of permanent erosion control, vegetation, drainage structures and/or features. 5.7 Septic Drainfields The approximate location of the proposed septic drainfield is presented on the Site Plan in Appendix A of this report. Based on the septic drainfield location with relation to the existing and proposed topography, the drainfield is not expected to adversely influence critical slopes. This is also based on compliance with all recommendations in this report. 5.8 Structural Mitigation With respect to landslide alleviation or slope improvements, structural mitigation is not necessary for this project. Revetment is recommended for drainage control as presented earlier in this report. This determination is based on the anticipated improvements of the project, engineering conclusions, and compliance with all recommendations provided in this report. Envirotech Engineering, PO Box 984 Beltair, Washington 98528 Ph. 360-275-9374 Fax: 360-275-4789 page 20 D. Elliot Geotechnical Report E Island View Road Parcel 22122-43-00080 Mason County, W.shington October 25. 201' 6.0 CLOSURE Based on the project information provided by the owner, the proposed development, and site conditions as presented in this report, it is Envirotech's opinion that additional geotechnical studies are not required to further evaluate this Project. Due to the inherent natural variations of the soil stratification and the nature of the geotechnical subsurface exploration, there is always a possibility that soil conditions encountered during construction are different than those described in this report. It is not recommended that a qualified engineer performs a site inspection during earthwork construction unless fill soils will influence the impending foundation. However, if native, undisturbed subsurface conditions found on -site are not as presented in this report, then a geotechnical engineer should be consulted. This report presents geotechnical design guidelines, and is intended only for the owner, or owners' representative, and location of project described herein. This report should not be used to dictate construction procedures or relieve the contractor of his responsibility. Any and all content of this geotechnical report is only valid in conjunction with the compliance of all recommendations provided in this report. Semantics throughout this report such as `shall,' `should' and `recommended' imply that the correlating design and/or specifications must be adhered to in order to potentially protect life and/ or property. Semantics such as 'suggested' or 'optional' refer that the associated design or specification may or may not be performed, but is provided for optimal performance. The recommendations provided in this report are valid for the proposed development at the issuance date of this report. Changes to the site other than the expected development, changes to neighboring properties, changes to ordinances or regulatory codes, or broadening of accepted geotechnical standards may affect the long-term conclusions and recommendations of this report. By developing the property and following the recommendations provided in this report, the property owner(s) shall be required to acknowledge in writing the risks inherent in developing in a geologic hazard area, to accept the responsibility of any adverse effects which may occur to the subject property or other properties as a result of the development, and to agree to convey the knowledge of this risk to persons purchasing the site by filing a notice on the property title. The services described in this report were prepared under the responsible charge of Michael Staten, a professional engineer with Envirotech. Michael Staten has appropriate education and experience in the field of geotechnical engineering in order to assess landslide hazards, earthquake hazards, and general soil mechanics. Please contact Michael Staten at 360-275-9374 if you have any questions, comments, or require additional information. Sincerely, Envirotech Engineering Michael Staten, P.E. Geotechnical Engineer PO Box 984 F3el1 iir. I,Vashii .tun 98528 Ph. 3('0 -?75-9374 Fax: 360-275-4789 pace 21 cat dietecl3t►ical Report L Island Vier Road Parcel 22122-43-00080 t C o nt . Washington October 25. 201? APPENDIX A SITE PLAN APPRX AREA FOR FUTURE DWELLING EXISTING BARN STORNVATER PIPE WITHIN BOTTOM OF NATURAL SWALE (APPRX) PROPOSED DWELLING SEPTIC DRAINFIELD AREA A APPRX LI OF FILL x x 50 FT SETBACK FR TOP OF CRITICAL SL APPROXIMATE TOP OF 407+ SLOPES NOTES. 1, EROSION CONTROL MAY BE REQUIRED FOR THIS SITE, GENERAL LOCATIONS ARE DEPICTED, AND ALTERNATIVES MAY BE UTILIZED AS EXPLAINED IN THE GEOTECHNICAL REPORT. 2. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR. CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIBAR SOURCE, AND INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL REPORT. 3. BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR, LOCATIONS OF SITE FEATURES THAT ARE SHOWN HERE, SUCH AS TOP OF SLOPES, TOE OF SLOOPES, WATER FEATURES, ETC.., WITH RELATION TO THE PROPERTY LINES MUST BE VERIFIED BY THE OWNER. RECOMMENDATIONS IN THE GEOTECHNICAL REPORT PROVIDE SETBACKS, BUFFERS, DEPTHS, ETC.. WITH RELATION TO GEOLOGIC FEATURES, NOT PROPERTY LINES. THESE GEOLOGIC FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING PROPERTIES. LEGEND TEMPORARY 'EROSION CONTROL SLOPE INDICATOR 80 EXISTING CONTOUR TP1 TEST PIT SCALE, 1 INCH = 100 FEET EXISTING DRIVEWAY EGETATION FROM TOP OF CAL SLOPE PICKERING PASSAGE PROJECT/ OWNER/ LOCATION, SINGLE FAMILY RESIDENCE GEOTECHNICAL REPORT D ELLIOT E ISLAND VIEW ROAD PARCEL 22122-43-00080 MASON COUNTY. WASHINGTON ENGINEER, ENVIROTECH ENGINEERING PO BOX 984 BELFAIR, WASHINGTON 98528 360-275-9374 SITE PLAN APPENDIX B SOIL INFORMATION TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: D Elliot Geotechnical Report PROJECT NO: 12101 CLIENT: Dean Elliot LOCATION: Parcel 22122-43-00080 Mason County, Washington INITIAL DEPTH OF WATER: N/A DEPTH -0 =8 0 12 -14 16 18 - 20 SOIL STRATA, SAMPLERS AND TEST DATA I No Groundwater Encountered This information pertains only to this boring and should not be interpreted as being indicitive of the entire site. USCS DESCRIPTION DATE OF LOG: 10/19/2012 LOGGED BY: MCS EXCAVATOR: N/A DRILL RIG: None ELEVATION: N/A FINAL DEPTH OF WATER: N/A STANDARD PENETRATION TEST LL PI CURVE DEPTH N 10 30 50 SM Light brown, moist SILTY SAND with gravel, medium dense. Gravel is well -graded and subrounded. Sand is mostly medium. Low plasticity. Very dense, brown and gray, hardpan Moderate to strong cementation Pockets of poorly graded gravel Bank observation to approximately 20.0 feet ENVIROTECH ENGINEERING Geotechnical Engineering uy TEST PIT LOG TEST PIT NUMBER TP-2 PROJECT: D Elliot Geotechnical Report PROJECT NO: 12101 CLIENT: Dean Elliot LOCATION: Parcel 22122-43-00080 Mason County, Washington INITIAL DEPTH OF WATER: N/A SOIL STRATA, DEPTH SAMPLERS USCS AND TEST DATA 8 10 =12 =14 =16 18 20 No Groundwater Encountered DESCRIPTION DATE OF LOG: 10/19/2012 LOGGED BY: MCS EXCAVATOR: N/A DRILL RIG: None ELEVATION: N/A FINAL DEPTH OF WATER: N/A STANDARD PENETRATION TEST LL PI _ CURVE DEPTH N 10 30 50 Brown, very moist, soft CLAY with silt, sand and trace of gravel. Sand is fine. Medium plasticity. Stiff. Some orange and gray. Denser with depth. Bank observation to approximately 4.0 feet This information pertains only to this boring and should not be interpreted as being indicitive of the entire site. ENVIROTECH ENGINEERING Geotechnical Engineering Map Unit Description: Everett gravelly sandy loam, 5 to 15 percent slopes — Mason County, Washington Mason County, Washington Eh —Everett gravelly sandy loam, 5 to 15 percent slopes Map Unit Setting Elevation: 50 to 500 feet Mean annual precipitation: 55 to 90 inches Mean annual air temperature: 48 to 50 degrees F Frost -free period: 160 to 180 days Map Unit Composition Everett and similar soils: 100 percent Description of Everett Setting Landform: Terraces Parent material: Glacial outwash Properties and qualities Slope: 5 to 15 percent Depth to restrictive feature: 20 to 40 inches to strongly contrasting textural stratification Drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of panding: None Available water capacity: Very low (about 1.2 inches) Interpretive groups Land capability (nonirrigated): 4s Typical profile 0 to 7 inches: Gravelly ashy sandy loam 7 to 21 inches: Extremely gravelly sand 21 to 60 inches: Very gravelly sand Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 7, Jun 29, 2012 Natural Resources Web Soil Survey Conservation Service National Cooperative Soil Survey 10/18/2012 Page 1 of 1 Map Unit Description: Kitsap silt loam, 5 to 15 percent slopes —Mason County, Washington Mason County, Washington Kb—Kitsap silt loam, 5 to 15 percent slopes Map Unit Setting Mean annual precipitation: 37 inches Mean annual air temperature: 50 degrees F Frost -free period: 160 to 200 days Map Unit Composition Kitsap and similar soils: 100 percent Description of Kitsap Setting Landform: Escarpments, terraces 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 11 to 30 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Very high (about 17.3 inches) Interpretive groups Land capability (nonirrigated): 3e Typical profile 0 to 7 inches: Silt loam 7 to 38 inches: Silt loam, silty clay loam 38 to 60 inches: Stratified silt to silty clay loam Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 7, Jun 29, 2012 Natural Resources Web Soil Survey Conservation Service National Cooperative Soil Survey 10/18/2012 Page 1 of 1 Map Unit Description: Rough broken land —Mason County, Washington Mason County, Washington Rb—Rough broken land Map Unit Setting Mean annual precipitation: 50 inches Mean annual air temperature: 50 degrees F Frost -free period: 180 days Map Unit Composition Rough broken land and similar soils: 100 percent Description of Rough Broken Land Properties and qualities Slope: 45 to 90 percent Depth to restrictive feature: 20 to 72 inches to densic material Drainage class: Well drained Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Low (about 4.3 inches) Interpretive groups Land capability (nonirrigated): 7e Typical profile 0 to 4 inches: Gravelly loam 4 to 43 inches: Very gravelly loam 43 to 60 inches: Very gravelly sandy loam Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 7, Jun 29, 2012 Natural Resources Conservation Service Web Soil Survey 10/18/2012 National Cooperative Soil Survey Page 1 of 1 nformation on this File Original and Fest Copy wllh Department of Ecology Second Copy — Owner's Copy Third Copy -- Driller's Copy (1) OWNER: Name Terry Asbjornsen (2) LOCATION OF WELL: County WATER ELL REPORT Start Card No. W 055904 UNIQUE WELL f.D. i ABC 060 STATE OF WASHINGTON Water Right *mill No. Island View Rd. Grapeview, WA 98546 Mason . SE ,, SE t/4s« 22 T. 21N N„R 2W (78) STREET ADDRESS OF WELL (or nearest address) Ts)Abd View Rd. (3) PROPOSED USE: (4) TYPE OF WORK: IN Domestic U Irrigation ❑ DeWater Owner's number of well (It more than one) Abandoned El Now well f$ Deepened U Reconditioned Cl Industrial ❑ Municipal ❑ Teat Well ❑ Other ❑ Method: Dug ❑ Cable Ih1 Rotary 0 (5) DIMENSIONS: Diameter of well 6 Drilled 74 feet. Depth of completed well 74 Bored ❑ Driven (71 Jetted CJ (6) CONSTRUCTION DETAILS: Casing Installed. 6. " Diem. Iron 0 kw 69 Welded Dc " Diem. from R. I" Liner Installed ❑ Threaded 0 — Diarn. from ft to Perforations: Yes Li No Type of perforator used SIZE of perforations perforations from perforations from perforations from Screens: Yes ® No O Manufacturer's Name Cook Type finless wire wrap Diam. 5 Slot size 40 tram Diam. Slot size hem In. by ft to ft. to ft. to Model No. 69 5.10 74 h. to Gravel packed: Yes ❑ No ® Size of gravel Gravel placed from h. to Surface seal: Yea fg No ❑ To what depth? Material used in seal Bentonite Did any strata contain unusable water? Yes ❑ Type of water? Method of sealing strata If (7) PUMP: Manufacturer's Name Type; SUD. (8) WATER LEVELS: Static level Artesian pressure Artesian water is controlled by Berry Land -surface elevation above mean sea level 48 18 No gg Depth of strata It below top of well Date lbs. per square inch Date Grapeview, WA 98546 (10) WELL LOG or ABANDONMENT PROCEDURE DESCRIPTION Formation: Describe by color, character, size of material and structure, and show thickness 01 aquders and the kind and nature at the material in each stratum penetrated, with at least one entry for each change of Information. Brown clay inches. Brown hardpan ft. MATERIAL Cemented gravel Tight gravel w/ water ft. ft. In. It. fL ft. H.P. 1/2 (Cap, valve, etc.) WELL TESTS: Drawdown is amount water level is lowered below static level Was a pump lest made? Yes ❑ No DI If yes, by whom? Yield: gat/min. with ft. drewdown after 11 ft. ft. Recovery date (tuna taken as zero when pump turned off) (water level measured from wee lop to water level) Time Water Level Time Water Level Time Water Level Date of test Sailer test 8 _ gal./min. with 20 ft, drawdown alter Airiest eel./ min. with stem set at ft. for Artesian Row g.p.m. Date Temperature of water Was a chemical analysis made? Yes ❑ No IN hrs. hrs. - 7 -- Work Started ‘J/.1.b/94 .18. Completed WELL CONSTRUCTOR CERTIFICATION: O 0 T12 12 45 45 60 60 74 4 .19 I constructed and/or accept responsibility for construction at this well, and its compliance with all Washington well construction standards. Materials used and the information reported above are true to my best knowledge and belief. NAME Address (Signed) Davis Drilling (PERSON, FIRM, OR r7PORATlOrr) (TYPE OR PANT) Belfar, WA 98528 lMx.n4 bC( (Mal OR R License No. _., 1706 Contractor's floeo!istWISDI1100A Date Sept 1994 (USE ADDITIONAL SHEETS IF NECESSARY) ,18 ECL 050-1-20 (2193) " f 4.; 0 a O C Rf E L a a..r lFi R R CI l/1 O m 0 (8) WATER LEVELS: Static level 50 meeker, pressure Artesian water Is controlled by File Original and First Copy with Department of Ecology Second Copy — Owner's Copy Third Copy — Drlller's Copy (1) OWNER: Name Terry Asbiornsen start card No.W 055903 WATER WELL REPORT uNlauEwELLI.D_! ARC 067 STATE OF WASHINGTON Water Right Panel No. Atea10pIsland View Rd. Grapeview, WA 98546 (2) LOCATION OF WELL: Canny Mason _ SE 1/4 SE t/4sec 22 T. 21N N., R 23/V/WM. (2a) STREET ADDRESS OF WELL tor nearest address) Island View Grapeview, WA 98546 (3) PROPOSED USE: f' Domestic industrial ❑ Municipal ❑ (10) WELL LOG or ABANDONMENT PROCEDURE DESCRIPTION 0 Irrigation Teat WOther ❑ Form„ion: Describe by color, character, Sze of matenal and structure, and show Ihiceese of aquifers fJ {3e Water ea ❑ end the hind and nature of the material in each stratum penetrated. with at least one entry toe each change of information. (4) TYPE OF WORK: Owner's number of well (N more than one) Abandoned ] New well g Method: Dug ❑ Bored ❑ Deepened 0 Cable Pf3 Driven Reconditioned ❑ Rotary El Jetted 0 DIMENSIONS: Diameter of well Drilled 82 feet. Depth of completed wall 6 2 inches. h. CONSTRUCTION DETAILS: Casing Installed: 6 mew - from 0 kw 77 ft. Welded EN ' Dlam. from R M if Liner installed ❑ Threaded ❑ ' Diem. from ft. to ft. Perforations: Yes ❑ No El Type of perforator used SIZE of perforations in. by fn. perforations from ff. to ft. perforations from ft to ft. perforations from ft. to - ft. Screens: Yes ® No ❑ Manufacturer's Name Cook Type S }a1 nl PSs wire wrap Model No. Diarn. 5 _ Slot size 40 from 77 tL to 83 fL Diem. Slot size from ft. to ft. Gravel packed: Yes ❑ No a size of gravel Gravel placed from ft. to Surface seal: Yes ❑C No ❑ To what depth? Material used In seal ____ ,,� Did arty strata contain unusable water? Yes ❑ No +L+ I Type of water? Depth of strata Method of seating strata off PUMP: Manufecnyers Name Gri Type: SLID. Land -surface elevation above mean sea level It. below top of well Date lbs. per square inch Date H.P. (Cap, valve, etc.) WELL TESTS: Drawdown Is amount water level is lowered below static level Was a pump teat made? Yes ❑ No ® If yes. by whom? Yield: gal./min. with ft. drawdown after TV hrs. Recovery data (time taken as zero when pump turned off) (water level measured from wen lop to water level) Time Water Level Time Water Level Time Water Level Date oftest !test Baiter test 10 gal./min. with 22 ft. drawdown alter Airtest gal./min. with stern set at ft. for Artesian flow ,g.p.m. Dale Temperature of water Was a chemical analysts made? Yes ❑ No hrs. hrs. MATERIAL Brown clay Brown hardpan Cemented sand & gravel Brown hardpan w/water FROM TO 0 14 14 27 27 60 60 82 work started ')/"3/..V4 .19. Completed y/ 13%94 19 WELL CONSTRUCTOR CERTIFICATION: I constructed and/or accept responsibility for construction of this well, and its compliance with all Washington well construction standards. Materials used and the information reported above are true to my best knowledge and belief. NAME Davis 1 i11imp fF •.-.•... .Ffi.ORCORPORATIONI (PIPEORPRrNT) Address Be] fair, WA 98528 (Signed) i3 f n �t t rcense No. 1706 A Date Sept. 1994 .19 (USE ADDITIONAL SHEETS IF NECESSARY) ECL 050-1.20 (2/931'' 1 APPENDIX C SLOPE STABILITY STABLE Slope Stability Analysis System New User Project : Elliot Datafile : dynamic STABLE Version 9.03.00u Bishop TITLE dynamic ********************************************************** UNITS (Metric/Imperial) = I **************************-.i**is**********k**3-************** GEOMETRY DEFINITION POINTS NO. X Y 1 0.000 0.000 2 50.000 2.000 3 50.000 -5.000 4 80.000 -30.000 5 130.000 -34.000 6 0.000 -7.000 7 13.000 0.520 8 18.470 0.740 9 23.950 0.960 10 29.420 1.180 11 34.890 1.400 12 40.370 1.610 13 45.840 1.830 14 51.320 -6.100 15 56.790 -10.660 16 62.260 -15.220 17 67.740 -19.780 18 73.210 -24.340 19 78.680 -28.900 20 84.160 -30.330 21 89.630 -30.770 22 95.110 -31.210 23 100.580 -31.650 24 106.050 -32.080 25 111.530 -32.520 26 117.000 -32.960 LINES Lo X Hi X SOIL 1 2 1 2 3 1 6 3 3 4 2 4 5 2 ***********+*************************+*a***********k****** : Bishop SOILS SOIL NAME LINETYPE-PEN COHESION FRICTION UNIT WT. 1 overburden CONTINUOUS -BLACK 100.00 15.0 128.000 STABLE Slope Stability Analysis System New User Project : Elliot Datafile : dynamic 2 vashon sediment 0.00 400.0 40.000 *****************k************'***********+**************** PORE PRESSURE SPECIFICATION SOIL PIEZO RU EXCESS Y/N/P Value Value 1 N 0.000 0.000 2 N 0.000 0.000 PIEZOMETRIC SURFACE POINT POINT PORE PRESSURES POINT PRESSURE ********************************************************** SLIP DIRECTION (+/- ******************k*************************************** SLIP -CIRCLES AUTOMATIC Circle Centre Grid Extremities 106.000 13.000 *************** * * * 117.000 * *************** 2.000 X spacing -- no. of cols (max 10)= 10 Y spacing -- no. of rows (max 20)= 20 Grid 1 Circles through point 7 Grid 2 Circles through point 8 Grid 3 Circles through point 9 Grid 4 Circles through point 10 Grid 5 Circles through point 11 Grid 6 Circles through point 12 Grid 7 Circles through point 13 Grid 8 Circles through point 14 Grid 9 Circles through point 15 Grid 10 Circles through point 16 Grid 11 Circles through point 17 Grid 12 Circles through point 18 Grid 13 Circles through point 19 : Bishop GEOTEXTILE FABRIC WRAP AROUND TRENCH TO AT LEAST ENTIRE BOTTOM OF TRENCH BEFORE PLACING GRAVEL 12' DEEP, 8' WIDE TRENCH FILLED WITH 3/4' TO 1 1/2' WASHED GRAVEL DIRECTION OF WATER FLOW 2.5 FT 2'x2'x5' WOOD POST OR EQUIVALENT OR BETTER EXISTING GROUND SURFACE SILT FENCE - CRESS SECTION N.T.S. 3ENERAL NOTES, 2'x2' WOOD POST (TYP) OR EQUIVALENT OR BETTER 2 6 FT MAX. O.C. EXISTING GROUND SURFACE 12' DEEP, 8' WIDE TRENCH FILLED WITH 3/4' TO 1 1/2' WASHED GRAVEL BOTTOM EXTENTS OF GEOTEXTILE FABRIC I. SHOULD THE TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES SHOWN ON THESE PLANS PROVE TO BE INADEQUATE DURING CONSTRUCTION, THE CONTRACTOR SHALL INSTALL ADDITIONAL EROSION AND SEDIMENT CONTROL FACILITIES, I. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE INSPECTED DAILY AND IMMEDIATELY MAINTAINED, IF NECESSARY. 3. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT LACE UNTIL THE UPSLOPE AREAS HAVE BEEN PERMANENTLY STABILIZED, TEMPORARY EROSION CONTROL NOTES' IN -0R ALL AREAS WHICH HAVE BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAND )ISTURBING ACTIVITIES, AND WHERE NO FURTHER WORK IS ANTICIPATED FOR A 'ERIOD EXCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE MMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING OR OTHER APPROVED :ROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR. GRASS SEEDING LONE WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH iEPTEMBER. HOWEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST OF THE OWNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING, NETTING JR OTHER APPROVED TREATMENT, )RY SEASON (MAY 1 THRU SEPTEMBER 30) -- THE CLEARING OF LAND, INCLU➢ING THE IEMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LIMITED TO )NLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE )THERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR OTHERWISE DISTURBED , 3Y NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR. UNLESS IMMEDIATE ITABILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL AREAS CLEARED OR OTHERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED THROUGH THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, -REE DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED 'LAN OF ACTION. UNLESS OTHERWISE APPROVED BY THE COUNTY, SEEDING, -ERTILIZING AND MULCHING OF CLEARED OR OTHERWISE DISTURBED AREAS SHALL BE 'ERFORMED DURING THE FOLLOWING PERIODS, MARCH 1 TO MAY 15, AND AUGUST 15 TO ICTOBER 1. SEEDING AFTER OCTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION IF THE PROJECT IS IMMINENT AND THE ENVIROMENTAL CONDITIONS ARE CONDUCIVE 10 SATISFACTORY GROWTH. IN THE EVENT THAT PERANENT STABILIZATION IS NOT 'OSSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHING, NETTING, 'LASTIC SHEETING, EROSION BLANKETS, ETC., MUST BE INSTALLED BY NO LATER THAN SEPTEMBER 30. :N THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT ACTIVITIES ARE DISCONTINUED FOR AT LEAST 4 CONSECUTIVE DAYS, THE ]WNER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION AND SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT EAST ONCE EVERY WEEK. THE OWNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR [HE MAINTENANCE AND REPAIR OF ALL EROSION AN SEDIMENT CONTROL FACILITIES. dET SEASON (OCTOBER 1 THRU APRIL 30) -- ON SITES WHERE UNINTERUPTED 'ONSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE IEMOVAL OF EXISTING VEGETATION AND OTHER GROUND COVER, SHALL BE LIMITED TO AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HOURS IN THE EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SEDIMENT TRANSPORT OFF -SITE IS OBSERVED. ILL CLEARED OR DISTURBED AREAS SHALL RECEIVE APPROPRIATE PROTECTIVE :OVER OR BE OTHERWISE STABILIZED, SUCH AS MULCHING, NETTING, PLASTIC IHEETING, EROSION BLANKETS, FREE DRAINING MATERIAL, ETC., WITHIN 5 DAYS AFTER SAVING BEEN CLEARED OR OTHERWISE DISTURBED IF NOT BEING ACTIVELY WORKED. TILT FENCING, SEDIMENT TRAPS, SEDIMENT PONDS, ETC., WILL NOT BE VIEWED AS ADEQUATE COVER IN AND OF THEMSELVES. IN THE EVENT THAT ANY LAND AREA NOT 3EING ACTIVELY WORKED REMAINS UNPROTECTED OR HAS NOT BEEN APPROPRIATELY iTABILIZED 5 DAYS AFTER HAVING BEEN CLEARED, ALL CONSTRUCTION ACTIVITY ON THE SITE, EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY, SHALL :MMEDIATELY CEASE UNTIL SUCH A TIME AS AFOREMENTIONED LAND AREA HAS BEEN APPROPRIATELY PROTECTED OR STABILIZED. SILT FENCE SILT FENCE - DETAIL N.T.S. HAY OR STRAW MATTING GEOTEXTILE FABRIC AND WIRE MESH 6 FT 5 FT I. STRAW SHALL BE AIR DRIE➢, AND FREE FROM WEED SEEDS AND COARSE MATERIAL. 2. APPLY AT APPROXIMATELY 75 TO 100 POUNDS PER 1000 SQUARE FEET OF GROUND. 3, MINIMUM THICKNESS SHALL BE 2 INCHES. 4. HAY OR STRAW IS SUBJECT TO BLOWING. KEEP MOIST OR TIED DOWN. PERMANENT EROSION CONTROL NOTES' SEEDING FOR RAW SLOPES FT 1. BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES, SWALES, LEVEL SPREADERS AND SEDIMENT BASINS. 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE, FOLLOWING SURFACE ROUGHENING. PERFORM ALL OPERATIONS ACCROS5 OR PERPENDICULAR TO THE SLOPE, 3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE APPLIED AT THE RATE OF 120 POUNDS PER ACRE. 4, SEED BEDS PLANTED BETWEEN MAY 1 AND OCTOBER 31 WILL REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO FOSTER AND PROTECT THE ROOT STRUCTURE. 5, SEED BEDS PLANTED BETWEEN NOVEMBER 1 AND APRIL 30, ARMORING OF THE SEED BED WILL BE NECESSARY, (e.g., GEOTEXTILES, JUTE MAT, CLEAR PLASTIC COVERING). 6. FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS' RECOMMENDATIONS, AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY ADJACENT TO WATER BODIES AND WETLANDS. USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE. NAME PROPORTIONS PURITY GERMINATION BY WEIGHT(%) (X) (''..) REDTOP (AGROSTIS ALBA) 10 ANNUAL RYE (LOLIUM MULTIFLORUM) 40 CHEWING FESUE 40 (FESTUCA RUBRA COMMUTATA) (JAMESTOWN, BANNER, SHADOW. KOKET) WHITE DUTCH CLOVER 10 (TRIFOLIUM REPENS) MULCHING 92 90 98 90 97 80 96 90 1. MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 1000 POUNDS PER ACRE, 2. MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES GREATER THAN 24 (HORIZONTALVERTICAL). 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON. ALL AREAS REQUIRING MULCH SHALL BE COVERED BY NOVEMBER 1. 1. GEOTEXTILE FILTER FABRIC TYPE SHALL BE PER SPECIFIED IN THE 'STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN,' OR APPLICABLE COUNTY STANDARDS 2. GEOTEXTILE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF EACH BARRIER TO AVOID USE OF JOINTS. IF JOINTS ARE NECESSARY, FILTER FABRIC SHALL BE SPLICED TOGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6 -INCH OVERLAP AND SECURELY FASTENED AT BOTH ENDS TO THE POST, 3. STANDARD FILTER FABRIC SHALL BE FASTENED USING 1' STAPLES OR TIE WIRES (HOG RINGS) B 4 IN SPACING. 4. POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED IN THE DETAILS ON THIS SHEET, AND DRIVEN SECURELY INTO THE GROUND, 5, WIRE MESH SHALL BE 2'X2'X14 GAUGE OR EQUIVILENT. THE WIRE MESH MAY BE ELIMINATED IF -XTRA-STRENGTH FILTER FABRIC (MONOFILAMENT), AND CLOSER POST SPACING IS USED. 5. A TRENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS ON THIS SHEET ALONG THE LINE OF THE POSTS AND UPSLOPE FROM THE SILT FENCE. 7. SILT FENCES SHALL BE LOCATED DOWNSLOPE FROM THE CLEARING LIMITS OF THE PROJECT. PROJECT/ OWNER/ LOCATION' SINGLE FAMILY RESIDENCE GE❑TECHNICAL REP❑RT D ELLIOT PARCEL 22122 43 00080 MASON COUNTY, WASHINGTON ENGINEER, ENVIROTECH ENGINEERING PO BOX 984 BELFAIR, WASHINGTON 98528 360-275-9374 ER❑SI❑N C❑NTR❑L