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Home My WebLink AboutGEO2016-00006 BLD2016-00083 - BLD Engineering / Geo-tech Reports - 2/29/2016 MASON COUNTY DEPARTMENT OF COMMUNITY DEVELOPMENT Planning Division P O Box 279, Shelton, WA 98584 910 (360)427-9670 Geotechnical ReportReview Acceptance Letter February 29, 2016 JEANNE SIMS PO BOX 302 ALLYN WA 98524 Case No.: GE02016-00006 Parcel No.: 122203490364 Project Description: Geotech report for nre residence. The Geotechnical Report for JEANNE SIM has been received and reviewed by the Planning Department. The report was prepared by Michael Staten PE 434045 dated 2/5/2016. 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, &h.--- Allan Borden Land Use Planner Mason County Planning Department Comments: 2/29/2016 Page 1 of 1 GE02016-00006 Mason County Review Checklist For a Geotechnical Report Instructions: This checklist is intended to assist Staff in the review of a Geotechnical Report_ The Geotechnical Report is reviewed for completeness with respect to the Resource Ordinance. If an item is found to be not applicable, the Report should explain the basis for the conclusion. The Report is also reviewed for clarity and consistency. If the drawings, discussion, or recommendations are not understandable, they should be clarified. If they do not appear internally consistent or consistent with the application or observations on site, this needs to be corrected or explained. If resolution is not achieved with the author, staff should refer the case to the Planning Manager or Director. S Applicant's Name: 9'4 S Permit# r VV W 16 ` 00666 Parcel# 1724 D 7-0 i G • 60M727 Date(s) of theDocument(s)reviewed: 2,10�24 1 6 (1) (a)A discu ion of general geologic conditions in the vicinity of the proposed development, OK? Comment: (b) A discussion of specific soil types OK? V Comment: (c) A discy�sion of ground water conditions OK? ✓ Comment: (d) A discussion of the upslope geomorphology OK? ✓ Comment: (e) A disc ssion of the location of upland waterbodies and wetlands OK? t� Comment: (f) A discussion of history of landslide activity in the activity in the vicinity, as available in the referen d maps and records OK?_{Comment: wGi (2) A site plan which identifies theVirh 0=- ent and geologic features. OK? Comment: (3) Locations d logs of explorato h les or p best OK?Comment: 'ZG (4) The area of the proposed devel pment, the boundaries of the hazard, and associated buffers and setbacks shall be delineated (top, both sides, and toe)on a geologic map of the site. OK? V" Comment: (5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which in the details of pro osed gr a changes. OK. V Comment: 'VtJ07 � (6) A description and results of slope tabilit analy s performed for both static and seismic loading conditions.Analysis should examine worst case failures. The analysis should include the Simplified Bishop's Method of Circles.The minimum static safety factor is 1.5, the minimum seismic sa ty factor is 1.1. and the quasi-static analysis coeffients should be a value of 0.15. OK? Comment: (7) (a)Approprjate restrictions oh Olacement of drainage features OK? Comment: (b) Appro late restrictions on placement of septic drain fields OK? ✓ Comment: (c) Appropriate restrictions on placement of compacted fills and footings OK? ✓ Comment: (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes on the property. Page 1 of 2 Form Effective June 2008 PLANNING 6azab ' RcCEIVED FEB - 82016 615 W. Alder Street Geotechnical Report for Single Family Residence ZZ a Sherwood Creek Road Parcel No. 12220-34-90364 Mason County, Washington February 5, 2016 Project#1604 Oreoared For: �:q h M2 sI 1v1S PO Box 302 �P�� WA�F s�9> Allyn, Washington 98524 Prepared By: 2/5✓16 Envirotech Engineering F�ISTV, `mow PO Box 984 SS��NALti�G Belfair, Washington 98528 Phone: 360-275-9374 � S Mason County Department of Community Development Submittal Checklist For a Geotechnical Report Instructions: This checklist must be submitted with a Geotechnical 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_ If an item found to be not applicable, the report should explain the basis for the conclusion. Applicant/Owner 7�z ►l StrhS., Parcel# i Z 220-3q---9030- Site Address Z S/e►'u/a (1) (a)A discussion of general geologic conditions in the vicinity of the proposed development, Located on page(s) � (b) A discussion of speck soil types Located on page(s) 7 (c) A discussion of ground water conditions Located on page(s) -7 (d) A discussion of the upslope geomorphology Located on page(s) 3 (e) A discussion of the location of upland waterbodies and wetlands Located on page(s) 3 (f) A discussion of history of landslide activity in the activity in the vicinity, as available in the referenced maps and records Located on page(s) 0 (2) A site plan which identifies the important development and geologic features_ Located on Map(s) S.�e_P/cw (3) Locations and logs of explqrato7 holes or probes. Located on Map(s) (4) The area of the proposed development,the boundaries of the hazard,and associated buffers and setbacks shall be delineated top, both sides, and toe)on a geologic map of the site. Located on Map(s) lam, - P/a-i (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) -Iq>, / A-,. ,ZP_ (6) A description and results of slope stability analyses performed for both static and seismic loading conditions.Analysis should examine worst case failures. The analysis should include the 8implified'l[shop's Method of Circles. The minimum static safety factor is 1.5,the minimum seismic safety.factor is 1.1. and the quasi-static analysis coeffients should be a value of 0.15. Located on page) /0 (7) (amppropriate,re actions on placement of drainage features Located an pages / (b) Appropriate rstrictions on placement of septic drain fields Located on pa (s) 19 (c) Appropriate restrictions on placement of compacted fills and footings Located on page(s) / /$- Page 1 of 2 Form Effective June 2008 Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report. r (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes on the property_ . Located on page(s) �S (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes on the property Located on page(s) / (8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation removal. Located on page(s) 19 (9) 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) /f (10) An analysis of both on-site and off-site impacts of the proposed development. Located on page(s) z (11) Specifications of final development conditions such as,vegetative management, drainage, erosion control, and buffer widths. Located on page(s) /7 — %9 (12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. Located on page(s) / (13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of existing and pro osed development on the site_ Located on Map(s) �, Arn I, 144iJ+c•e 1 1544jerl hereby certify under penalty of perjury that I am a civil engineer licensed in the State of Washington with specialized knowledge of geotechnical/geological engineering or a geologist or engineering geologist licensed in the State of Washington with special knowledge of the local conditions. I also certify that the Geotechnical Report, dated re L S 2.�1IE , and entitled A r;"' ;, meets all the requirements of the Mason County Resource Ordinance, Landslide Hazard Section, is complete and true,that the assessment demonstrates conclusively that the risks posed by the landslide hazard can be mitigated through the included geotechnical design recommendations,and that all hazards are mitigated in such a manner as to prevent harm to property and public health and safety. (Signature and Stamp) C LYpF �NASy�� ' 7�s116 �0" Fss GIST Page 2 of 2 Form Effective June 2008 Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report. � S Table of Contents 1.0INTRODUCTION ...... ..»....»»......... ..»»» 1 1.1 PROJECT INFORMATION.....................................................................................................................l 1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK.........................................................................1 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.................................................................................................................3 2A 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 CONDrnoNS..................................................................................................7 3.3.1 Groundwater...............................................................................................................................7 4.0 ENGINEERING ANALYSES AND CONCLUSIONS.......................................................................8 4.1 SLOPE STABILITY................................................................................................................................8 41.1 Slope StabilityAnalysis.............................................................................................................10 4.2 EROSION............................................................................................................................................11 4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION.............................................................................12 4.31 Liquefaction..............................................................................................................................12 4.4 LANDSLIDE,EROSION AND SEISMIC HAZARDS CONCLUSIONS.......................................................12 4.5 LATERAL EARTH PRESSURES...........................................................................................................13 4.6 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 Settlentent................................................ .................................................................................15 5.1.3 Concrete Slabs-on-Grade-.........................................................................................................15 5.2 EARTHWORK CONSTRUCTION RECOMMENDATIONS......................................................................15 5.2.1 Excavation.................................................................................................................................15 S.2.2 Placement and Conrpac&n of Native Soils and Engineered Fill...........................................15 5.2.3 Retaining Wall Backfill............................................................................................................16 5.2.4 Wet Weather Consideradons....................................................................................................17 5.3 BUILDING AND FOOTING SETBACKS.................................................................................................17 5.4 SURFACE AND SUBSURFACE DRAINAGE...........................................................................................17 5.5 VEGETATION BUFFER AND CONSIDERATIONS.................................................................................18 5.6 TEMPORARY AND PERMANENT EROSION CONTROL.......................................................................Is 5.7 SEPTIC DRAINFIELDs............... ._ .__............................................................ 5.8 STRUCTURAL MITIGATION...............................................................................................................19 6.0 CLOSURE............................................................................................................................................20 Appendix A-Site Plan Appendix B-Soil Information Appendix C-Slope Stability Appendix D—Erosion Control � S 1.0 INTRODUCTION Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a planned single family residence located at Sherwood Creek Road, identified as parcel number 12220-34-90364,Allyn,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 in support of the proposed development as detailed below. The proposed development, as provided herein,and the surrounding area that may influence the development, is identified throughout this report as the Project. An initial geotechnical evaluation of the Project was conducted by Envirotech on January 6, 2015.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. The land is currently undeveloped with partial clearing. The planned development consists of a 1-or 2-story single family residence and other ancillary features typical of this type of development. 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. 1.2 Purge 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: Envirotech Engineering 22 E.Sherwood Creek Road PO Box 994 page I Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 • Review project information 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. t ESTERLNG OR ! O QOS JI W W Project E E MERLON CREEK RD OQ 'opm,OEs, W P f Coo 1s HERO ? c JJJ FFF Et P� S2On EURE'A.,DR b O W U � W � d w EW TOR RDGE RD W w ti �9a Vicinity Map from Mason County Website Envirotech Engineering LO Sherwood Creek Road PO Box 984 page 2 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the Project was gathered on January 6, 2015 by a representative 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 Sherwood Creek Road, an existing paved roadway. The Project is currently undeveloped land as previously mentioned. The access road extends near the north property line, and Sherwood Creek Road borders the property to the south. Beyond the property, rural residential development exists. Vegetation on and near the Project consists primarily of secondary growth firs, cedars, alders, 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%,approximately 35 feet to the south of the planned development.The maximum critical slope is approximately 78%with a vertical relief of approximately 20 feet. Ascending grades are generally located to the southeast of the planned development.These slopes are relatively minor within 300 feet of the Project,with no apparent slope grades of at least 15%. 2.2.1 Upslope Geomorphology The upland area of the property and beyond is generally situated on a crest of glacial origin. 23 Surface Drainage Runoff originating upslope of the development is mostly diverted away from the property by accommodating topography. Excessive scour, erosion or other indications of past drainage problems were not observed within the immediate vicinity of the planned development. 23.1 Upslope Water Bodies There are no apparent water bodies or wetlands located upslope from the planned Envirotech Engineering 22 1=Sherwood Creek Road PO Box 984 page 3 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 development that would significantly influence the Project. 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. These slope instability indicators or other significant mass wasting on the property or within the general vicinity of the Project were not observed or discovered during research. Indications of past landslides, current unstable slopes, deep-seated slope problems, or surFcial slope failures were not observed during the site visit. Project ,K ,r Aerial Photo from Mason County Website Envirotech Engineering 2 E Sherwood Creek Road PO Box 984 page 4 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 3.0 SUBSURFACE INVESTIGATION Information on subsurface conditions pertaining to the Project was primarily gathered on January 6, 2015 by a representative 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 applicable water well report(s). Water well reports were utilized to estimate ground water levels,and if sufficient,were used in identifying subsoil types. 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 3 feet below the existing ground surface, and observing cut slopes/ shoreline banks of up to 12 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 to medium dense soils in the upper 36 inches, and very dense soils from 36 inches 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, Qg. 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 Belfair 7.5-minute Quadrangle, Mason, Kitsap, and Pierce Counties, Washington' by Michael Polenz, Nicholas J. Hehemann, Lsaabelle Y. Srikhan, and Robert L. Logan,July 2009,provides the following caption(s)for the project area: Envirotech Engineering 22.E Sherwood Creek Road PO Box 984 page 5 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 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. The Project is currently composed of native soils without indications of borrowed fill.Within test pit locations, soils within the upper 3 feet of natural ground were observed to be moist, brown silty sand with gravel(SM). Soils below the upper 3 feet layer to a depth of at least 10 feet below the ground surface were observed to be mostly grey, low moisture, silty sand with gravel (SM), 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. 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 site soils are described as Alderwood Gravelly Sandy Loam,k, with 15%-30% slopes, and Everett Gravelly Sandy Loam, 0%to 5% Slopes Ed.The soil designations are depicted in the aerial photograph below, and descriptions are provided in Appendix B of this report. Soil Survey From USDA Natural Resources Conservation Service 3.3.1 Groundwater From the water well reports)and knowledge of the general area,permanent groundwater is at least 50 feet directly below the property at the building pad location. Surface seepage or perched groundwater at shallow depths was not observed on-site,nor indicated on the well reports. However, some groundwater is expected to flow directly above the hardpan on occasion. Envirotech Engineering 22 ESherwood Creek Road PO Box 984 page 7 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 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. Geotechnical engineering considers excessive wet weather and `design' earthquakes in order to provide an acceptable factor 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 defming 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' regarding potential landslide activity. Stable slopes are generally not prone to landslides due to small grades and accommodating geology. However, this site is considered inherently hazardous due the existing geology and/ or topography, and additional 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: Envirotech Engineering 22 Sherwood Creek Road PO Box 984 page 8 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 a a Project f.r�aaaue 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 not within terrain labeled `highly unstable' relating to soils. DNR labeled portions of this project as medium and high slope instability with relation to slopes. This delineation is primarily dependent upon slopes and convergence. Secondly, lithology and precipitation are modeled within this delineation. th summary, this designation is based on mapping without field observations or knowledge of the specific site geology or soils. A Resource Map from the DNR Forest Practices Application Review System is provided below: Envirotech Engineering 2?£Sherwood Creek Road PO Box 984 page 9 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 " "" E,7, Project ■ - .. T% Resource Map from Washington State Department of Natural Resources Website SOILS—o,Resmrce.Mn on H)*ic Soils High Unstable IU D- ffigb4,Erodible rmHighly[.,nstable& ifirhev Fiodibk M4w " ;No Data or Gravel Pits SLOPE—osi Resouu ma o■lv 71 me&=Slope lnstabiiv �High Slope , 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 Envirotech Engineering 22 t: Sherwood Creek Road PO Box 984 page 10 Parcel 12220-34-90364 Belfair, Washington 98528 Mason County, Washington Ph. 360-275-9374 February 5,2016 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 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: 135 pcf Angle of internal friction: 32 degrees Cohesion: 0 psf Soils below 5 feet in depth Soil unit weight: 140 pcf Angle of internal friction: 40 degrees Cohesion: 400 psf Based on the slope stability analysis, minimum factors of safety were determined to be less than 1.5 relative to static slope failures, and less than 1.1 with relation to seismic conditions.These factors of safety 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 2.2 and 1.8, respectively. See the slope stability information in Appendix C for a depiction of input parameters and example of outputs. 4.2 Erosion Based on the USCS description of the Project soils, the surface soils are considered moderately erodible. According to the Resource Map from the Washington State DNR, as provided above, the Project is not within terrain labeled `highly erodible.' This Project is 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(11b),and Kitsap Silt Loam on slopes 15%or greater(Kc). Envirotech Engineering 22 C Sherwood Creek Road PO Box 984 page 11 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 It is our opinion that minor erosion control recommendations provided in this report is sufficient for the development of this Project, and additional engineered erosion control plans are not required. Temporary and permanent erosion control measures are required for site development. Extents of 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 Department of Ecology Water Quality Program. 4.3 Seismic Considerations and Liquefaction 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 4 miles to the south of this Project. This information is based on the USGS Quaternary Fault and Fold Database for the United States. Potential landslides due to seismic hazards have been considered, and are addressed in the Slope Stability Analysis Section provided earlier in this report. Soils immediately below the expected foundation depth for this Project are generally Type D, 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. 431 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. 4.4 Landslide,Erosion and Seismic Hazards Conclusions DNR did not indicate historic landslide activity near the Project. Mapped slope conditions, as delineated by the Departments of Ecology and/ or 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 Envirotech Engineering 2 2 C- Sherwood Creek Road PO Box 984 page 12 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 surface conditions, and other pertinent information, it is our opinion that the proposed development may occur in accordance with the recommendations in this geotechnical report. 4.5 Lateral Earth Pressures 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. Significant retaining structures are not anticipated for this Project. If retaining walls are later planned for this Project, prescriptive requirements from the County should be adhered to. For retaining structures with a height exceeding County prescriptive requirements, additional design parameters must be accounted for in the retaining wall analysis, and recommendations should only be provided by a qualified engineer after the type of backfill is acquired, inclination of backfill slope is estimated, and the final wall height is determined. 4.6 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 E Sherwood Creek Road PO Box 984 page 13 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 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 12 inches(15 inches for 2 stories) shall be placed at a minimum of 24 inches below the existing ground surface. For a columnar load of no more than 3 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 may be completed upon a site inspection by a geotechnical engineer after the foundation excavation is completed. Envirotech Engineering 'Z2 E Sherwood Creek Road PO Box 984 page 14 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 5.1.2 Settlement Total and differential settlement that a stricture 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 (Retained on U.S. Sieve #10 or greater) that is placed over undisturbed, competent native subgrade or engineered fill per the Earthwork Recommendations Section below. 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 this report, concrete slabs should also be designed for structural integrity and environmental reliability. This includes vapor barriers 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 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 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 Envirotech Engineering 22>`Sherwood Creek Road PO Box 984 page 15 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 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. F❑❑TING COMPACTED NATIVE SOILS OR ENGINEERED 1 FILL I UNIIISTURBED SUBGRADE 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. Because of moisture sensitivity, importing and compacting engineered fill may be more economical than compacting disturbed native soils. 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 %Finer(by weight) 6" 100 3" 60— 100 No.4 20—60 No.200 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. 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 As previously mentioned, significant retaining structures are not anticipated for this Project. However, if used, native soils may be used as retaining wall backfill for this Project. Backfill may also consist of engineered fill or borrow materials approved by a Envirotech Engineering 2 2 6 Sherwood Creek Road PO Box 984 page 16 Parcel 12220-34-90364 Belfair, Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 1 1 geotechnical engineer. Placement, compaction and extents of retaining wall backfill should also be specified by a geotechnical engineer or qualified professional. 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 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. 53 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 25 feet footing setback from the face of the nearby descending slopes exceeding 400/6. See the figure below and the Site Plan in Appendix A for an illustration of the setbacks. STRUCTURE TOP OF SLOPE SLOPE FACE - E� I 1—I I 1 —i- �-- SETBACK — — FOOTING From the illustration above, structures may be located closer to the top of slope by extending the foundation deep enough to maintain the recommended setback. In addition, the required setback may be reduced by mitigation,and subsequently would require additional geotechnical studies. 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 from the structures to an appropriate protected discharge area. Leakage of water pipes, both drainage and supply lines,shall be prevented at all times. If impervious thresholds are exceeded per Mason County code, then engineered stormwater management plans are required for this project. The drainage engineer must coordinate with a geotechnical engineer for input with relation to slope stability prior to submitting drainage plans. Envirotech Engineering 2 2 E Sherwood Creek Road PO Box 984 page 17 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 If stonmwater management plans are not required for this project, then the following recommendations should be followed. Both footing perimeter drains and roof drains are required for this Project. Subsurface water intercepted in the footing perimeter drains, and stonmwater collected from roof drains shall be separately tight-lined to the recommended outlet. Roof and foundation drains may share a tightline if an above ground drainage outlet is allowable and a backflow preventer is installed within the pipe system in order to prevent roof water from entering the foundation area. For this project, we recommend that roof infiltration is located outside of the construction setbacks provided in this report,conforming to the Mason County Small Parcel Stormwater Plan. 5.5 Vegetation Buffer and Considerations For this project, we believe that a detailed clearing and grading plan is not warranted unless Mason County thresholds are exceeded, and basic vegetation management practices should be adhered to. 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. Vegetation Buffer—Vegetation shall not be removed from the face of the critical slope or within a distance of 15 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 during construction should include minimizing the removal of vegetation to the least extent possible. Erosion control measures during construction may include stockpiling cleared vegetation, sift fencing, intercepting swales, berms, straw bales, plastic cover or other standard controls. Although other controls may be used,.if adequate, sift 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,if necessary. 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 Envirotech Engineering Z2 6 Sherwood Creek Road PO Box 984 page 18 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 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.The following Surface and Subsurface Drainage Section may have additional recommendations with relation to permanent erosion for surface drainage features. 5.7 Septic Drainfields There is no septic drainfield associated with this site. The proposed structure will connect to a standard sewer system located in the paved driveway to the north of the property. 5.8 Structural Mitigation With respect to landslide alleviation or slope improvements, structural mitigation is not necessary for this project. This determination is based on the anticipated improvements of the project, engineering conclusions,and compliance with all recommendations provided in this report. Envirotech Engineering E Sherwood Creek Road PO Box 984 page 19 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 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. 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 Robert McNearny,E.I.T. Michael Staten,P.E. Staff Engineer Geotechnical Engineer Envirotech Engineering ;aI L Sherwood Creek Road PO Box 984 page 20 Parcel 12220-34-90364 Belfair,Washington 98528 Mason County,Washington Ph. 360-275-9374 February 5,2016 APPENDIX A SITE PLAN el 9 EXISTING PAVED DRIVEWAY SCALE, 1'=60' PROPOSED GRAVEL DRIVEWAY 0 15 30 60 25' C❑NSTRUCTI❑N PROPOSED STRUCTURE SETBACK 80 116t 214t ��. ��' 40t 15' VEGETATION BUFFER * TP1 ACD ti 60 SILT FENCE TOP OF SLOPE 3a6� ' ✓, ,�� PROPERTY LINE TOE OF SLOPE A PROJECT/ OWNER/ LOCATION, NOTES, 1. EROSION CONTROL MAY BE REQUIRED FOR THIS SITE. GENERAL LOCATIONS SINGLE FAMILY RESIDENCE ARE DEPICTED, AND ALTERNATIVES MAY BE UTILIZED AS EXPLAINED IN THE GEOTECHNICAL REPORT GEOTECHNICAL REPORT. 2. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR. ARIENS CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND — XXX SHERWOOD CREEK ROAD INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL LEGEND PARCEL 12220-34-90364 REPORT. MASON COUNTY WA H N TON 3. BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR, LOCATIONS TEMPORARY ENGINEER, OF SITE FEATURES THAT ARE SHOWN HERE, SUCH AS TOP OF SLOPES, TOE EROSION CONTROL ENVIROTECH ENGINEERING OF SLOPES, WATER FEATURES, ETC— WITH RELATION TO THE PROPERTY PO BOX 984 LINES MUST BE VERIFIED BY THE OWNER. RECOMMENDATIONS IN THE SLOPE INDICATOR BELFAIR, WASHINGTON 98528 GEOTECHNICAL REPORT PROVIDE SETBACKS, BUFFERS, DEPTHS, ETC„ WITH 360-275-9374 RELATION TO GEOLOGIC FEATURES, NOT PROPERTY LINES. THESE GEOLOGIC —80— EXISTING CONTOUR FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING I&TP TEST PIT SITE PLAN PROPERTIES. APPENDIX B SOIL INFORMATION VERTICAL AND HORIZONTAL SCALE, SCALE: 1"=20' PROPOSED STURCTURE 0 rJ 10 20 EXISTING GRADE p p p p p p p p MEDIUM DENSE SILTY SAND WITH GRAVEL p po po p� po pap pa o ... VERY DENSE SHERWOOD CREEK ROAD Q,GLACIAL TILL 0 Q 0 0 0 p p p p p p oa po po po pap po pa po po po o�'� SECTION A-A PROJECT/ OWNER/ LOCATION, SINGLE FAMILY RESIDENCE GEOTECHNICAL REPORT ARIENS XXX SHERWOOD CREEK ROAD PARCEL 12220-3-90364 MASON COUNTY, WASHINGTON NOTES ENGINEER 1) MINOR GRADE CHANGES REQUIRED IN ORDER TO ACHIEVE ENVIROTECH ENGINEERING POSITIVE DRAINAGE PO BOX 984 2) THE SOIL PROFILE IS ACCURATE FOR THE DEPTH OF BELFAIR, WASHINGTON 98528 THE OBSERVED TEST PITS AT THE SPECIFIED LOCATIONS. 360-275-9374 LOWER DEPTHS ARE BASED ON SITE GEOLOGY, WELL LOG(S), AND/OR EXPERIENCE IN THE GENERAL AREA, SOIL PROFILE TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: Ariens Geotechnical Report DATE OF LOG: 1/6/2015 PROJECT NO: 1604 LOGGED BY: RJM CLIENT: Johannas Areins EXCAVATOR.- N/A LOCATION: Parcel 12220-34-9364 DRILL RIG: None Mason County, Washington ELEVATION: N/A INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A SOIL STRATA, STANDARD PENETRATION TEST DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE AND TEST DATA DEPTH N 10 30 50 0 SM Brown, moist, loose to medium dense SILTY SAND with GRAVEL. Gravel is primarily well-graded and subangular. 1 Sand is mostly medium. Low plasticity. 2 Hardpan 3 Excavation terminated at approximately 3.0 feet 4 5 6 7 8 9 i 10 No Groundwater Encountered ENVIROTECH ENGINEERING This information pertains only to this boring and should not be Geotechnical Engineering interpreted as being indicitive of the entire site. Map Unit Description:Alderwood gravelly sandy loam,15 to 30 percent slopes—Mason County, Washington Mason County, Washington Ac—Alderwood gravelly sandy loam, 15 to 30 percent slopes Map Unit Setting National map unit symbol: 2t627 Elevation. 0 to 1,000 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 46 to 52 degrees F Frost-free period: 160 to 240 days Farmland classification: Farmland of statewide importance Map Unit Composition Alderwood and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Alderwood Setting Landfonn: Hills, ridges Landform position(two-dimensional): Backslope Landform position (three-dimensional): Nose slope, side slope,talf Down-slope shape: Convex, linear Across-slope shape: Convex Parent material: Glacial drift and/or glacial outwash over dense glaciomarine deposits Typical profile A -0 to 7 inches: gravelly sandy loam Bw1 - 7 to 21 inches: very gravelly sandy loam Bw2-21 to 30 inches: very gravelly sandy loam Bg-30 to 35 inches: very gravelly sandy loam 2Cd1 -35 to 43 inches. very gravelly sandy loam 2Cd2-43 to 59 inches: very gravelly sandy loam Properties and qualities Slope: 15 to 30 percent Depth to restrictive feature: 20 to 39 inches to densic material Natural 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 37 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low(about 2.7 inches) Interpretive groups Land capability classification(irrigated): None specified Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B USDA Natural Resources Web Soil Survey 1/31/2016 5illillilll Conservation Service National Cooperative Soil Survey Page 1 of 2 Map Unit Description:Alderwood gravelly sandy loam,15 to 30 percent slopes--Mason County, Washington Other vegetative classification: Limited Depth Soils (G002XS301 WA),Limited Depth Soils(G002XF303WA),Limited Depth Soils(G002XN302WA) Minor Components Indianola Percent of map unit: 5 percent Landform: Eskers, kames, terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape. Linear Everett Percent of map unit: 5 percent Landform. Moraines, eskers, kames Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down-slope shape: Convex Across-slope shape: Convex Shalcar Percent of map unit. 3 percent Landform: Depressions Landform position(three-dimensional): Dip Down-slope shape: Concave Across-slope shape: Concave Norma Percent of map unit: 2 percent Landform: Depressions, drainageways Landform position(three-dimensional): Dip Down-slope shape: Concave, linear Across-slope shape: Concave Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 11, Sep 15, 2015 usDA Natural Resources Web Soil Survey 1/31/2016 Conservation Service National Cooperative Soil Survey Page 2 of 2 Map Unit Description:Everett gravelly loamy sand,0 to 5 percent slopes—Mason County, Washington Mason County, Washington Ed—Everett gravelly loamy sand, 0 to 5 percent slopes Map Unit Setting National map unit symbol. 2hk6 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 Farmland classification: Prime farmland if irrigated Map Unit Composition Everett and similar soils: 100 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Everett Setting Landform: Terraces Parent material: Glacial outwash Typical profile H1 -0 to 7 inches: gravelly ashy loamy sand H2- 7 to 21 inches. extremely gravelly sand H3-21 to 60 inches. very gravelly sand Properties and qualities Slope: 0 to 5 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water(Ksat). High to very high (5.95 to 19.98 in/hr) Depth to water table. More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low(about 2.5 inches) Interpretive groups Land capability classification(irrigated): None specified Land capability classification(nonirrigated). 4s Hydrologic Soil Group. A Other vegetative classification: Droughty Soils(G002XN402WA) Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 11, Sep 15, 2015 USDA Natural Resources Web Soil Survey 1/31/2016 2i Conservation Service National Cooperative Soil Survey Page 1 of 1 File Original and First Copy with Department of Ecology WATER WELL REPORT Application No. ._.__...._...._.......... -_, Second Copy-Owner's Copy Third C2Y-Driller's Copy STATE OF WASIIINGTON Permit No. .... .................—...... _ (1) OWNER: +.;(2) LOCATION OF WELL: M a-s-o n s W 1� s 8 20 22 1 W L • County_.......-----•--•..................-_.-_v.�__._............................._...._-..._.._. .........;i Seo._...._...__T... _-N..R..........._w.7V1_ Q Searing and distance from section or subdivision corner Q (3) PROPOSED USE: Domestic)a Industrial ❑ Municipal❑ (10) WELL LOG: Irrigation ❑ Test Well [] Other ❑ Formation:Describe by color,character,size of material and structure,and show thickness of aquifers and the kind and nature of the material in each (4) TYPE OF WORK? Owner's number of well at stratum penetrated,with at Ieast one entry for each change of formation. (if more than one).... ............................,.........- MATERIAL FROM TO H New well X1 Method:Dug [] Bored ❑ Deepened ❑ Cable (R Driven p T O Soil Reconditioned❑ Rotary❑ Jetted ❑ Q 0(5) DIMENSIONS: Diameter of well ._._6_...__........_inches. ! C Drilied.-._�_..___.-_..-ft. Depth of completed well........... --- 0 (6) CONSTRUCTION DETAILS: E Casing installed:---6__1•Dlant.from ft.to ..........5 Q it. Brown cong' L Threaded❑ _._T-" Diam.from.__.___..ft.to__ ._.._ft. Welded Q9 ___ _"Dlam.from_.___ ._ft.to___it. C d Perforations: Yes❑ No IR Water t Type of perforator used............................................... __._._- SIZE of perforations ___ _.__..... in. by -_._ __ in. _._..___...__perforations from._ ft.to perforations from ft. to _ft. C - -perforations from._ .-. ft. to _.W- ft. Screens: Yes[3 Nog] Manufacturer's Name-----.-_-_�.---� Model No __ Diam.__ .___Slat size from__._...... it.to ft. S Dlam.-__ _..Slot size ...._.___ from -.-__.. ft,to ._-_.__ft Gravel packed: Yes❑ No fk size of gravel:...—_.—__.—._- = Gravel placed from__.__............_....__.it.to---_..._......_.__.._._..It. RSurface seal: Yes ij No[3 To what depth? IL Material used In seal-.___......_..8 Q it t O fl 1 t e................ Did any strata contain unusable water? Yes❑ No)} [- Type of Depth of strata.--•---...------- Q Method of sealing strata off._..-................._.__.-_................__........ _. H (7) PUMP: Manufacturer's Name.----_--------8erkaIa X.....,..._..�._.-.___. 41 Type: ...............__.- .._ _ H.P_.1.............. (8) WATER LEVELS: above ur aces levation... N V -.._..._ ... 9�tatic Ievel .__.___-.9---------_...___fit. below top of well Date.__..4/4-7/7 \ C Artesian pressure-..-_...__ __lbs.per square inch Date...--_--_.....-..- OArtesian water Is controlled by.....-... ..-_.._.__..._.....-.._-------------- V (Cap,valve,etc.) LU(9) WELL TESTS: Drawdown Is amount water level Is 1F lowered below static level Work started-5_/1,5._..._.._.,Ig-7 5. Completed._—a/_W..__.,,19 7.5 O Was a pump test made? Yes❑ No)E] If yea.by whom?._-__,.................. C Yield: gal./min.with ft. drawdown after hrs. WELL DRILLER'S STATEMENT: ` This well was drilled under my jurisdiction and this report is " •• true to the best of my knowledge and belief. �] L Recovery data (time taken as zero when pump turned off) (water level R= measured from well top to water level) J(' iZ Time water Level Time Water Level Time Water Level Ne�12E----•-T-�I Q---• L~1l___D.r_1l.Zi1.f� QO.......I.1c-.............."' \ d (Person, Arm, or corporation) (Type or print) Q._ _ _ _- _. ._.-.... ..... .. . . .................................... _......----------_,------------------------ ............... Address....P_r.Q t...e o x 3 A jjy a...Wa s h -- . .._.... ...�.._. . - ------------------------i- ......_.__........_.........-.. ~ Data of test._ :.._._.._.._...._...._......... [Signed]..-- {.__..s..................... .................. Railer tesL_3Q-.._gal./min, drawdown (wen Driller) Artesian flow_— .._-•--••----..-g.p m. Date.......--.-.-_.-..._.... ``�� Temperature of water_........__..Was a chemical analysis made?Yes❑ No❑ License No.....O.J.2-Lt...............Date......5/1.7.._............. I9__7$ (USE ADDITIONAL SHEETS IF NECESSARY) S.F.No.7356--OS-(Rev.4 71). _Z3j,3 APPENDIX C SLOPE STABILITY STABLE Slope Stability Analysis System New User Project Ariens Datatile: DYNAMIC Bishop 1 SM CONTINUOUS-BLACK 0.00 32.0 135.000 2 HARDPAN CONTINUOUS-BLUE 400.00 40.0 140.000 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 (+/- X) = + +*#***###*+#**+*#*#****##*###**#***#***#**##****++#*##**#* SLIP-CIRCLES AUTOMATIC Circle Centre Grid Extremities 121.600 # 15.200 * * 136.800 * * *##*##**#***##* 0.000 X spacing -- no. of cols (max 10)= 10 Y spacing -- no. of rows (max 20)= 20 Grid 1 Circles through point 9 Grid 2 Circles through point 10 Grid 3 Circles through point 11 Grid 4 Circles through point 12 Grid 5 Circles through point 13 Grid 6 Circles through point 14 Grid 7 Circles through point 15 Grid 8 Circles through point 16 Grid 9 Circles through point 17 Grid 10 Circles through point 1s Grid 11 Circles through point 19 Grid 12 Circles through point 20 Grid 13 Circles through point 21 Grid 14 Circles through point 22 STABLE®2002 W Associates Ltd Printed on: 02JO2/16 @ 09:35:54 Page: 2 STABLE Slope Stability Analysis System New User Project Ariens Datatile: DYNAMIC Bishop 1 SM CONTINUOUS-BLACK 0.00 32.0 135.000 2 HARDPAN CONTINUOUS-BLUE 400.00 40.0 140.000 xz*xzx*xxx**xxzxxx*xx+zzxxtxxxx*xzf+xzxxxzzzxzzxzzzzx+**+x 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 ++++++*++xx+****#xxx*x+x****x#xx*xx**+z+****x**x**#+****++ SLIP DIRECTION (+/- X) _ + SLIP-CIRCLES AUTOMATIC Circle Centre Grid Extremities 121.600 15.200 * * 136.800 *x******+++#+x+ 0.000 X spacing -- no. of cols (max 10)= 10 Y spacing -- no. of rows (max 20)= 20 Grid 1 Circles through point 9 Grid 2 Circles through point 10 Grid 3 Circles through point 11 Grid 4 Circles through point 12 Grid 5 Circles through point 13 Grid 6 Circles through point 14 Grid 7 Circles through point 15 Grid 8 Circles through point 16 Grid 9 Circles through point 17 Grid 10 Circles through point 18 Grid 11 Circles through point 19 Grid 12 Circles through point 20 Grid 13 Circles through point 21 Grid 14 Circles through point 22 STABLES2002 MZAssociates Ltd Printed on: 02/02/16 @ 09:35:54 Page: 2 O O O O O O O O O O O N m 1 0 w l` O m O . . . . . . . . . ri ri r I ri r I ri ri r I r I H N I r) N OD O N U Q H 0 �I Q U) u a •• n u U 0 i 0 •li 0 n 0 44 >1 •n �S r1 i 0 +J N a Q � � 1 . 00 i . O 1 . 2 1 . 30 1 . 40 1 . 50 1 . 60 1 . 70 1 . so 1 _ 90 2 00 O 675 P r o j e c t A r i e n s D a t a f i 1 e D Y N A M I C Analysis Bishop 9TASLE.-2002 MZ As.o a lat.. Ltd APPENDIX D EROSION CONTROL GEOTEXTILE FABRIC GEOTEXTILE FABRIC WRAP AROUND TRENCH 2'x2' WOOD POST BETYP) AND WIRE MESH TO AT LEAST ENTIRE OR EQUIVALENT OR BETTER BOTTOM OF TRENCH e 6 FT MAX O.C. OS FT BEFORE PLACING GRAVEL 2'x2'x5' WOOD POST OR 6 FT 12' DEEP, 8' WIDE TRENCH EQUIVALENT OR BETTER EXISTING FILLED WITH 3/4' TO 1 1/2' GROUND SURFACE WASHED GRAVEL or VEGETAT N 2 T DIRECTION OF — 2.5 FT 12' DEEP, 8' WIDE WATER FLOW GROUND SURFACE ISTING TRENCH FILLED WITH 1 T 12' 3/4' TO 1 1/2' ME U qm mmw 2.5 FT T 25 FT WASHED GRAVEL OR VEGETATION g� BOTTOM EXTENTS OF GEOTEXTILE FABRIC SIL7 FENCE - DETAIL $jLT FENCE - CROSS SECTION N.T.S. N.T.S. HAY OR STRAW MATTING ENERAL NOTES+ 1. STRAW SHALL BE AIR DRIED, AND FREE FROM WEED SEEDS AND COARSE MATERIAL. SHOULD THE TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES SHOWN ON 2, APPLY AT APPROXIMATELY 75 TO 100 POUNDS PER 1000 SQUARE HESE PLANS PROVE TO BE INADEQUATE DURING CONSTRUCTION, THE CONTRACTOR FEET OF GROUND. HALL INSTALL ADDITIONAL EROSION AND SEDIMENT CONTROL FACILITIES. 3. MINIMUM THICKNESS SHALL BE 2 INCHES. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE 4. HAY OR STRAW IS SUBJECT TO BLOWING. KEEP TWIST OR TIED NSPECTED DAILY AND IMMEDIATELY MAINTAINED, IF NECESSARY. DOWN. 1. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT IN LACE UNTIL THE CONTROAREAS HAVE BEEN PERMANENTLY STABILIZED, PERMANENT EROSION CONTROL NOTES, OR ALL AREAS WHICH HAVE BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAND SEEDING FOR RAW SLOPES ISTURBING ACTIVITIES, AND WHERE NO FURTHER WORK IS ANTICIPATED FOR A 1. BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL ERIOD EXCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES, MMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING OR OTHER APPROVED STALES, LEVEL SPREADERS AND SEDIMENT BASINS. ROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR. GRASS SEEDING 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE, LONE WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH FOLLOWING SURFACE ROUGHENING. PERFORM ALL OPERATIONS ACCROSS EPTEMBER. HOWEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST 13F IN PERPENDICULAR TO THE SLOPE. HE OWNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING, NETTING 3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE R OTHER APPROVED TREATMENT. APPLIED AT THE RATE OF 120 POUNDS PER ACRE. RY SEASON (MAY 1 THRU SEPTEMBER 30) -- THE CLEARING OF LAND, INCLUDING THE 4. SEED BEDS PLANTED BETWEEN MAY 1 AND OCTOBER 31 WILL EMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LIMITED TO REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO FOSTER AND PROTECT THE ROOT STRUCTURE. NLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE THERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR OTHERWISE DISTURBED , 5. SEED BEDS PLANTED BETWEEN N BE NE ER 1 AND APRIL 30, NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR. UNLESS IMMEDIATE GEOTEARMORING OF THE SEED BED WILL BE NECESSARY, (e.g., TABILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL 6. FER FERTILIZERS JUTE MAT, CLEAR PLASTIC COVERING). AS CLEARED OR OTHERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED 6. FERTILIZERS ARE TO BE USED ACCORDING IZ SUPPLIERS' THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, RECOMMENDATIONS. AMOUNTS SHOULD T MINIMIZED, ESPECIALLY DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED ADJACENT TO WATER BODIES AND WETLANDS. AN OF ACTION. UNLESS OTHERWISE APPROVED BY THE COUNTY, SEEDING, USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION ERTILIZING AND MULCHING OF CLEARED OR OTHERWISE DISTURBED AREAS SHALL BE CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE. ERFORMED DURING THE FOLLOWING PERIODS: MARCH I TO MAY 15, AND AUGUST 15 TO TOBER 1. SEEDING AFTER OCTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION PROPORTIONS PURITY GERMINATION THE PROJECT IS IMMINENT AND THE ENVIROMENTAL CONDITIONS ARE CONDUCIVE NAME BY WEIGHT<%) (%) (%) 0 SATISFACTORY GROWTH. IN THE EVENT THAT PERANENT STABILIZATION IS NOT OSSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHING, NETTING, REDTOP (AGROSTIS ALBA) 10 92 90 LASTIC SHEETING, EROSION BLANKETS, ETC., MUST BE INSTALLED BY NO LATER THAN ANNUAL RYE (LOLIUM MULTIFLORUM) 40 98 90 EPTEMBER 30. CHEWING FESUE 40 97 80 (FESTUCAN THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT (JAMESTO N, BRUB A COR, S ADO CTIVITIES ARE DISCONTINUED FOR AT LEAST 4 CONSECUTIVE DAYS, THE WHITE BANNER, SHADOW, KOKET) WNER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION WHITE DUTCH CLOVER 10 96 90 (TRIFOLIUM REPENS) ND SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT EAST ONCE EVERY WEEK. THE OWNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR MULCHING HE MAINTENANCE AND REPAIR OF ALL EROSION AN SEDIMENT CONTROL FACILITIES. ET SEASON (OCTOBER 1 THRU APRIL 30) -- ON SITES WHERE UNINTERUPTED 1. MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD ONSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 1000 MOVAL OF EXISTING VEGETATION AND OTHER GROUND COVER, SHALL BE LIMITED POUNDS PER ACRE. AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HOURS IN 2. MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES 11111RANsPaRT E EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SEDIMENT GREATER THAN SHOULD <HORIZONTAIMMED ICAL). OFF-SITE IS OBSERVED. 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON. ALL LL CLEARED OR DISTURBED AREAS SHALL RECEIVE APPROPRIATE PROTECTIVE AREAS REQUIRING MULCH SHALL BE COVERED BY NOVEMBER 1. OVER OR BE OTHERWISE STABILIZED, SUCH AS MULCHING, NETTING, PLASTIC HEETING, EROSION BLANKETS, FREE DRAINING MATERIAL, ETC., WITHIN 5 DAYS AFTER AVING BEEN CLEARED OR OTHERWISE DISTURBED IF NOT BEING ACTIVELY WORKED. ILT FENCING, SEDIMENT TRAPS, SEDIMENT PONDS, ETC., WILL NOT BE VIEWED AS DEQUATE COVER IN AND OF THEMSELVES. IN THE EVENT THAT ANY LAND AREA NOT EING ACTIVELY WORKED REMAINS UNPROTECTED OR HAS NOT BEEN APPROPRIATELY TABILIZED 5 DAYS AFTER HAVING BEEN CLEARED, ALL CONSTRUCTION ACTIVITY ON HE SITE, EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY, SHALL MMEDIATELY CEASE UNTIL SUCH A TIME AS AFOREMENTIONED LAND AREA HAS BEEN PPROPRIATELY PROTECTED OR STABILIZED. ILT FENCE PROJECT/ OWNER/ LOCATION, GEOTEXTILE FILTER FABRIC TYPE SHALL BE PER SPECIFIED IN THE 'STORMVATER MANAGEMENT MANUAL SINGLE FAMILY RESIDENCE OR THE PUGET SOUND BASIN,' OR APPLICABLE COUNTY STANDARDS . GEOTEXTILE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF GEOTECHNICAL REPORT ACH BARRIER TO AVOID USE OF JOINTS. IF JOINTS ARE NECESSARY, FILTER FABRIC SHALL BE SPLICED ARIENS TOGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT PARCEL 12220-34-90364 TH ENDS TO THE POST. MASON COUNTY, WASHINGTON STANDARD FILTER FABRIC SHALL BE FASTENED USING V STAPLES OR TIE WIRES (HOG RINGS) E 4 IN PACING. POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED IN THE DETAILS ON THIS SHEET, AND ENGINEER: DRIVEN SECURELY INTO THE GROUND. ENVIROTECH ENGINEERING . WIRE MESH SHALL BE 2'X2'X14 GAUGE OR EQUIVILENT. THE WIRE MESH MAY BE ELIMINATED IF PO BOX 984 XTRA-STRENGTH FILTER FABRIC CMONOFILAMENT), AND CLOSER POST SPACING IS USED. BELFAIR, WASHINGTON 98529 . A TRENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS ON THIS SHEET ALONG THE LINE OF THE 360-275-9374 OSTS AND UPSLOPE FROM THE SILT FENCE. . SILT FENCES SHALL BE LOCATED DOWNSLOPE FROM THE CLEARING LIMITS OF THE PROJECT. EROSION CONTROL Comment: Cv (e) Reecm`mended setba—carom the landslide hazard areas shoreline bluffs and the tops of other slop s on the prope / OK?�omment: l (8) Recommendations for the pr p ation of a detailed clearing and grading plan which specifically identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of egetation removal. OK? Comment: (9) 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 fromXosion, landslides and harmful construction methods. OK? V Comment: (10) An analysis both on-site and off-site impacts of the proposed development. OK? Comment: (11) Specifications of final development conditions such as, vegetative management, drainage, erosion control, and buffer widths. OK? f/ Comment: & r? - (12) Recommendations for the pr paration of structural mitigation or details of other proposed mitigation OK? tt// Comment: (13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of existing and propo ed evelo ment on the site. OK?_Comment: r Are the Documents signed and stamped? . Type and #of License: Pr T�O�� If not approved,what is the next action/recommendation for further action? at ao), Reviewed by on Time spent in review: SECOND REVIEW/ UPDATE: Reviewed by on Time spent in second review: THIRD REVIEW/UPDATE: Reviewed by on Time spent in third review: Disclaimer: Mason County does not certify the quality of the work done in this Geological Assessment Page 2 of 2 Form Effective June 2008