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HomeMy WebLinkAboutGEO2016-00044 BLD2016-00592 Addendum - BLD Engineering / Geo-tech Reports - 6/23/2016 Ev 'brotec.k Ev�,P'�wee►-i,wg PLANNING c,eotechv�caL, EvuvIrovl.vvev,-taL o Araivwge o izoadwaU June 23,2016 R E I VZ.D John Upchurch JUL 0 7 20 Janette Bennett 10871 North Shore Road 615 W. Alder Street Belfair,Washington 98528 Reference: Geotechnical Report Addendum#1 for Residential Property Located at 18920 State Route 106,Belfair,Washington Dear Mr.Upchurch and Mrs.Bennett, We are pleased to provide this geotechnical report addendum for the referenced project. This letter includes conclusions and recommendations for the project with regards to the recent earthwork/ land clearing,and revised septic drainfield area.Michael Staten with Envirotech conducted a recent site visit in June 2016 in order to identify changes of the property with relation to our original geotechnical investigation in December of 2013. We reviewed the septic drainfield location and design by OCS, and conclude that the drainfield will have no impact on slope stability. This is provided that only vegetation removal that is necessary for the drainfield installation is completed. Envirotech also reviewed the location of the planned residence, past clearing location and earthwork extents. We conclude that the land modification is acceptable, and has an adequate factor of safety regarding landslides.The residence must remain outside of fill limits,or foundations must extend through the fill,or bear atop structural fill per the original geotechnical report. Please call me at 360-275-9374 if you have any questions,or require additional information. Sincerely Envirotech Engineering CLY0 S NY,AS�IJi, 14 �+ 4304. ., �SSIr�'`ALt`�o, 6/23/16 Michael Staten,P.E. Project Director PO BOX 984 Belfair,Washington 98528 Off: 360-275-9374 Cell: 36o-689-6045 Fax: 360-275-4789 envirotech@geotechnicalinfo.com �v ';�o 1,L - OX-44 Y�L 61 A 2,� Geotechnical Report for Single Family Residential Property 18920 E State Route 106 Belfair, WA 98528 Parcel No. 12206-31-00070 Mason County, Washington December 10, 2013 Project 913115 Prepared For: John Upchurch P 1 CLYDE ST Jannett Bennett 910 Kieser Road Philadelphia, Tennessee 37846 12,110113 Prepared By: 0 �cts�Rti SSfDNAL��G Envirotech Engineering PO Box 984 Belfair, Washington 98528 Phone: 360-275-9374 Fax: 360-275-4789 1® Mayo. County Deportment of Community Deveiootmen L 0 7 2%' Su..-nitr�;v;;eckiis€For a Geoiechnical Repo d 615 W. Mer Street instructions: This checklist rnust be submitted with a Geotechnical Rewn and completed,signed, and s amued b"y the licensed professional(s)who prepared the Geoiechnical kepoit for review by Mason County pur-suant io .1y:4•iris 3 i.v_:rIy ��Sis[�ei a:v_c�€i�3saC_ _- -i 3EGii ec3esTi's e{}13e eif3F a 3r{�FEc,�'3iC,is`ia i$p€i4 i Siir3is T.E� 18ii1 tf to basis for the c o i hislon- - ApplicanVOtivner lAh Joc,hurc'�/" cnn-: CAV[e*arcei# r 1'206 -31 - 00070 Cl-ii2nii icy ( ��G`✓ I`�Ut�� 10 0) (a)A discussion of gene pi geologic conditions in the vicinity of the proposed development, Located on page(s) b diSCi4SSiCa F VI SiiECii7C SC[3i ty T.reS Located on pageisi 7 (c) A discussion of ground water conditions Located on--age(s) / (d) A discussion of the upslope geGmorphology Located on pages) ,el A discussion of:.-:e lecatior of upland v ater iodies and wetlands Located on page(s) j r i SCtiSSi:r:31 i5 c"Ii j/Of landslide actway in the activity in the Acinity,as available in the referenced maps and records ocatCd on pages, (2) A site plan which identirfes the i rtani development and geologic features. Located Oil Map(s) 9� (3) Locations and logs of explorat ry holes or probes_ (4) The area of the proposed development, the boundaries of the hazard, and associated buffers and setbacks shall be delineate (top, both sides,and toe)on a'geologic map of the site. rcAn (b) A aiini-m-urn of one Grass section at a scale which adequately depicts the subsurface profile,and Mnich incorporates the details-of pr---sad grade changes. .....LGwii C)f F F7f.Gl.Jk I ' ,12 - ((j) is-r"--fon and re n ::CS--mr s"Ope eabifit?e analyses perlbr led bir hh ua.je"".a tic apd conditions_Analysis should examine worst camfalwes_The anaWhs should'nclude the = V �. ,.,, iS r.sp's f athad of Cl as_Them unc static safety factor is 3_05,i'the m un selsFm sa b-i-k 3aCtor is t_I.and the sZ 53-jL G analysi-s-coelffierds should bee a valuee faf o-153. 1-o C€ad or,pagB(S) C, (!) (a)Appropriate estrictions on plac-ement of drainage features LOC:a ed on page(S) W (y A-c-o- a e.-wstr icuons erg placement�?f se,, I c if gelds Located on page(s) 21 :C -',uYi v rialE i ES riCzis�P1S�Jrt[r9i2Cerdlent at compacted fills and footings Located on page(s) 17, 19 Page I of 2 Form Effective June 2008 Jiscialmser_ Mason County does not Cerf+iy the quality of the e; is �- work don n � (d) Recommended buffers from t:e landslide hazard areas shoreline-bluffs and the tops of other slopas on the property_ Located on page(s) _to (a) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes on the property. Located on page(s) Z� - {$`) Fern r,tmeridations for the preparation of a derailed clearing and grading plan W-i-11 h.sped"Gee y idea it ies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation removal_ Located on page(s) 20 (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 Siope Fiore erosion, iands ides and ha riefui construction methods. Located on page(s) f 3 (410) An analysis of both on-site and off-site impacts of the proposed developmem. Located on page(s) 19 (i i) Specifications of;inai development conditions such as, vegetative management, arainage, erosion control, and buffer widths. Located on page(s) 2-0 'Z (Z 2) Recommendations for the preparation of structural mitigation,or details of other proposed mitigation. �( Located on pages) - (13) A s=.e map drawn t-scale showing the prDperty.bounoariM scale,north th art aw, and the location and nature of eAsting and proposed dev m elopent on fe sew. i, /"I i[ G���e �2 ev) hereby cerff y under renalt of peijury allot i am a civii i6riginear licensed_e the fli Washingtoa"i tPo'➢m speciaihmd knom ledge of gevt$%�3i�icr Ef�evii7gai�Qi ang"ter` arcing or a geologist or engirrGcaadng gec4ggist licarise d M fine St ete of Lv:: y`a_t=:a e S 3 - _ 'i.--v__ __ __ ______ _— ?j i':��� `_ i -==Luis 6c7 F 1`f.�Gii3= '-� _':aztscs.fLrGS _ Report. dated Oe'C' (��7-013 ,and entitled 5 1e. Fu,r J. L.,Lc P Tv'7 w2o e t; P' ,a4e f o U Pne -+S aH i<!3e MqS remaeins of the 8"Viason ODunty Reno'. Ord-hanw.Laiq'isllde Hazard,Sermon,is campWe and fie,the She assessiment demonsbmtss cor:clusive3ly that t-he risks posed by the tandsllde hazard can be sly tl a ed tumuugh the ini.iudeu gao-tai—AirrdGw aeSign aaao cs"Biceraw==lea.a"d thai ZA s am'11itigaied in such a maniner as n. ��>:32? h and s n':. (S.Wgibbra a?d S'&--=r:r Zvir Page 2 of 2 Form Effectdve June 2008 D vl fh..-r: Mas^ r J , f:does not Ce fs_ Nha^,J�li:1 o€t78N�=..L%-done In t1:S Ga vir..L_eS.t si-=Cc Rep-- !. TABLE OF CONTENTS 1.0 INTRODUCTION..................................................................................................................................I 1.1 PROJECT INFORMATION.....................................................................................................................I 1.2 P[TRPOSF.OF INVESTIGATION AND SCOPF,OF WORK.........................................................................1 2.0 SURFACE CONDITIONS....................................................................................................................4 2.1 GENERAL OBSERVATIONS..................................................................................................................4 2.2 TOPOGRAPHY......................................................................................................................................4 2.2.1 Upslope Geomorphology.............................................................................................................4 2.3 SURFACE DRAINAGE...........................................................................................................................4 2.3.1 Upslope Water Bodies.................................................................................................................4 2.4 SLOPE AND EROSION OBSERVATIONS................................................................................................5 3.0 SUBSURFACE INVESTIGATION......................................................................................................6 3.1 FIELD METHODS,SAMPLING AND FIELD TESTING............................................................................6 3.2 GENERAL GEOLOGIC CONDITIONS....................................................................................................6 3.3 SPECIFIC SUBSURFACE CONDITIONS..................................................................................................7 3.3.1 Groundwater...............................................................................................................................9 4.0 ENGINEERING ANALYSES AND CONCLUSIONS.....................................................................10 4.1 SLOPE STABILITY..............................................................................................................................10 4.1.1 Slope Stability Analysis.............................................................................................................13 4.2 EROSION..............................................•.............................................................................................13 4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION.............................................................................14 4.3.1 Liquefaction..............................................................................................................................15 4.4 LANDSLIDE,EROSION AND SEISMIC HAzARDS CONCLUSIONS.......................................................16 4.5 RETAINING WALLS AND LATERAL EARTH PRESSURES...................................................................16 4.6 ON-SITE AND OFF-SITE IMPACTS.....................................................................................................16 5.0 ENGINEERING RECOMMENDATIONS.......................................................................................17 5.1 BUILDING FOUNDATION RECOMMENDATIONS................................................................................17 5.1.1 Bearing Capacity.......................................................................................................................17 5.1.2 Settlement..................................................................................................................................18 5.1.3 Concrete Slabs-on-Grade..........................................................................................................18 5.2 EARTHWORK CONSTRUCTION RECOMMENDATIONS......................................................................18 5.2.1 Excavation.................................................................................................................................18 5.2.2 Placement and Compaction of Native Soils and Engineered Fill...........................................19 5.2.3 Wet Weather Considerations....................................................................................................20 5.3 BUILDING AND FOOTING SETBACKS.................................................................................................20 5.4 SURFACE AND SUBSURFACE DRAINAGE...........................................................................................20 5.5 VEGETATION BUFFER AND CONSIDERATIONS.................................................................................20 5.6 TEMPORARY AND PERMANENT EROSION CONTROL.......................................................................21 5.7 SEPTIC DRAINFIELDS........................................................................................................................21 5.8 STRUCTURAL MITIGATION...............................................................................................................21 5.9 DRIVEWAY CONSIDERATIONS................................................................................................21 6.0 CLOSURE............................................................................................................................................23 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 planned single family residence located at 18920 E State Route 106, identified as parcel number 12206- 31-00070, Belfair, Mason County, Washington, Section 6, Township 22 North, Range 1 West, Willamette Meridian. 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, John Upchurch, in support of the proposed development as detailed below. An initial geotechnical evaluation of the Project was conducted by Envirotech on November 26 h, 2013.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 property consists of a cleared area, wooded area, driveway and pad. The proposed development is expected to consist of a new single family residence, septic system and improved driveway. 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 Purpose of Investigation and Scope of Rork 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 Donald Porter Geotechnical Report PO Box 984 page 1 18920 E State Route 106 Belfair,Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax:360-275-4789 December 10,2013 • 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. Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 2 18920 E State Route 106 Belfair,Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County, Washington Fax: 360-275-4789 December 10,2013 NE BECK R � r i Z i - Project > i O G u E OAKSF E SLAKE RD T22N W HOOD CA �40 E ALT, Q. E CEpAR ST_ _ Z ESTA /► R� � E MAX LN p Devereaux sS E TOLL P�IE HILL RD — 4 3? E! E 0 3405(t i Vicinity Map from Mason County Website Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 3 18920 E State Route 106 Belfair,Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair, Mason County,Washington Fax: 360-275-4789 December 10.2013 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the Project was gathered on November 26", 2013 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 East State Route 106. The Project currently consists of a partially cleared land and the remaining portion of the lot is mainly wooded area and native vegetation. Beyond the property, residential development exists. Hood Canal is located over 50 feet to the north of the property line. Vegetation on and near the property consists primarily of furs, 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% are located on the property. The maximum critical slope is about 45%with a total critical vertical relief of approximately 25 feet. 2.2.1 Upslope Geomorphology The upland area of the property is appears to be situated on a hillside of glacial origin. The mapped geology indicates landslide deposits,but may not be accurate. 2.3 Surface Drainage Stormwater runoff originating upslope from the anticipated development appears to primarily sheet flow to the stream that runs near the east property line. Excessive scour, erosion or other indications of past drainage problems outside of the stream conveyance were not observed near the planned development. 23.1 Upslope Water Bodies There are no apparent water bodies or wetlands located upslope from the planned development that would significantly influence the Project,so long as the ordinary stream buffers are adhered to. Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 4 18920 E State Route 106 Beifair,Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax:360-2754789 December 10,2013 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. Stream incision, sloughing of highway cuts and other earth movements are known to exist near the property. t Project C E 2l.. 7, Aerial Photo from Mason County Website Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 5 18920 E State Route 106 Belfair, Washington 98528 Parcel 1 2206-3 1-00070 Ph. 360-275-9374 Belfair, Mason County, Washington Fax: 360-275-4789 December 10,2013 3.0 SUBSURFACE INVESTIGATION Information on subsurface conditions pertaining to the Project was primarily gathered on November 26 b, 2013 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 onsite. Information on subsurface conditions also included reviewing geological maps representing the general vicinity of the project, and water well reports originating from nearby properties. Envirotech measured the relative density of the near-surface in-situ soils by gauging the resistance of hand tools. 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 uncomfortably 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, Katelin Alldritt, Nicholas J. Hehemann, Isablle Y. Sarikhan, and Robert L.Logan,July 2009, provides the following caption(s)for the project area: Qls Landslide deposits--Gravel, sand, silt, clay, and boulders in slide body and toe; due to map scale, includes exposure of underlying units in scarp areas; angular to rounded clasts and grains; unsorted; generally loose,jumbled, and unstratified,but may locally retain primary bedding; commonly includes liquefaction features. Absence of a mapped slide does not imply absence of sliding or hazard as some slides are too small to show at map scale. Although the large Alderwood landslide southwest of Belfair may have been triggered by seismicity about 1.1 ka (see Structure),review of aerial photographs also suggests historic movement for this slide. The unit post-dates Vashon ice and is predominantly Holocene but locally may include some late Pleistocene deposits. Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 6 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-275-4789 December 10,2013 ' eeeKKKd+ Om aw am ,. outis t °°, Gm Project �' r On t Az Ox QP CVI } a OYd QF - ..���' . owl Oor CIO QV- r Geological Map Department of Natural Resources Washington State 33 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 Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 7 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair, Mason County,Washington Fax: 360-275-4789 December 10,2013 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, and indications of native-type fill. Within test pit locations, soils within the upper 4 feet of natural ground were observed to be moist, brown moderately dense silty sand with gravel(SM)and some clay. 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 are described as Alderwood Gravelly Sandy Loam,Ab, with 5% - 15% slopes and Alderwood Gravelly Sandy Loam, A,, with 15% - 30% slopes. The soil designations are depicted in the aerial photograph below, and descriptions are provided in Appendix B of this report. Project 790E Soil Survey From USDA Natural Resources Conservation Service Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 8 18920 E State Route 106 Belfair, Washington 98528 Parcel 1 2206-3 1-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-2754789 December 10,2013 7r'w"t' Ma ,Washington (WA6.45) 4 Map Map Unit Name Acres Percent Unit in of AOI Symbol AOI Ab Alderwood gravelly sandy 32.2 65.10/6 loam, 5 to 15 percent slopes Ac Alderwood gravelly sandy 15.3 30.9% loam, 15 to 30 percent slopes Subtotals for Soil Survey Area 47.5 96.0% Totals for Area of Interest 49.5 100.0% Soil Map Unit Legend 3.3.1 Groundwater From the water well report(s)and knowledge of the general area, permanent groundwater is at least 60 feet directly below the property at the building pad location. Perched groundwater at shallow depths was not observed on-site. Isolated areas of seepage has been reported, and some groundwater is expected to flow directly above the underlying denser soils in some locations. Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 9 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax:360-2754789 December 10,2013 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 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 `Unstable' regarding potential landslide activity. Unstable slopes are generally prone to landslides due to steep grades and non-accommodating geology. Historically, unstable terrains have known old landslides. 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 Donald Porter Geotechnical Report PO Box 984 page 10 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-2754789 December 10,2013 Mk S Urs 7A f Urs Scale 1:24,W0 fr 0 9NI 1000 IW "letrn w .. Z , f F 5 f 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 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. In 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 Donald Porter Geotechnical Report PO Box 984 page 11 18920 E State Route 106 Belfair,Washington 98528 Parcel 1 2206-3 1-00070 Ph. 360-275-9374 Belfair, Mason County, Washington Fax: 360-275-4789 December 10,2013 Project P Ih -LAY Y T .:12 416 Resource Map from Washington State Department of Natural Resources Website SOILS—On Resource Ma osh Hy dric Sois Highb,Unstable Highty Erodible MgWy Unstable& FRehh-Erodible No Data or Gravel Pits SLOPE—On Resource.Ma only Medium Slope InstabIkv _ High Slope Instabk, Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 12 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County, Washington Fax:360-275-4789 December 10,2013 4.1.1 Slope Stability Analysis 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: 130 pcf Angle of internal friction: 24 degrees Cohesion: 200 psf Soils below 5 feet in depth Soil unit weight: 138 pcf Angle of internal friction: 38 degrees Cohesion: 200 psf Based on the slope stability analysis, minimum factors of safety were determined to be 1.7 relative to static slope failures, and 1.2 with relation to seismic conditions. 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 of highly erodible. According to the Resource Map from the Washington State DNR, as provided above, the Project is not within a 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 (Hb), and Kitsap Silt Loam on slopes 15%or greater(Kc). 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, Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 13 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax:360-275-4789 December 10,2013 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 contain specific erosion control options recommended for this Project. Additional erosion control measures than what is initially established may need to be employed if excessive erosion occurs during construction, or required by the prevailing agency. Complete 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 0.46g to 0.59g.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. Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 14 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-275-4789 December 10,2013 PGA, 2% PE in 50y. 1150m/s. Site Class B. Project 500 � f 48' _ - z 46' 44" Kk 42° - 4 40' _ S WC f 36° 1.00 0.77 0.59 34' 0.46 0.35 - 0.27 P z = Q.21 32' 0.16 AZ Al 0.12 0.10km 30' 0.06 9 n Ion 9nn 43.1 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 Engineering Donald Porter Geotechnical Report PO Box 984 page 15 18920 E State Route 106 Belfair, Washington 98528 Parcel 1 2206-3 1-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-275-4789 December 10,2013 4.4 Landslide,Erosion and Seismic Hazards Conclusions DNR did indicate previous 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, and observed surface conditions, it is our opinion that the proposed development should occur in accordance with this geotechnical report. 4.5 Retaining Walls and 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 Donald Porter Geotechnical Report PO Box 984 page 16 18920 E State Route 106 Parcel 12206-31-00070 Belfair,Washington 98528 Belfair,Mason County,Washington Ph. 360-275-9374 F December 10,2013 Fax: 360-275-4789 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, driveways, 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 Terraghi 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 Building foundations should not be established in fill soils. Existing fill soils are located within the vicinity of the proposed building pad. For building on the existing fill, foundations should extend at least 12 inches below the bottom of the fill. Alternatively, the fill may be removed and replaced as engineered fill per 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 15 inches shall be placed at a minimum of 18 inches below the native 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 Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 17 18920 E State Route 106 Belfair,Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-275-4789 December 10,2013 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 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, Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 18 18920 E State Route 106 Belfair, Washington 98528 Parcel 1 2206-3 1-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax:360-275-4789 December 10,2013 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. FDOTING COMPACTED NATIVE SOILS OR ENGINEERED I FILL 1 I � UNIIISTURBED SUBGRADF<I 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 Particle 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 out Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 19 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax:360-2754789 December 10,2013 and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an engineer. 5.23 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. 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 30 feet footing setback from the top of critical descending slopes exceeding 40%. 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. 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 location at least 10 feet beyond the house, and the outside the 30 feet building setback. Roof and foundation drains may share a tightline if a backflow preventer is installed within the pipe system in order to prevent roof water from entering the foundation area. If subsurface infiltration is not utilized, an energy dissipater is required at the outlet. 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. Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 20 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-2754789 December 10,2013 For this project, we believe that a detailed clearing and grading plan is not warranted unless required by the MCRO. From a geotechnical standpoint, basic vegetation management practices should be adhered to. Vegetation is not restricted from slopes, but permanent erosion control should be employed per the following section of this report. 5.6 Temporary and Permanent Erosion Control Erosion control during construction should include minimizing the removal of vegetation to the least extent possible, and may include stockpiling cleared vegetation, silt fencing, intercepting swales, berms, straw bales, plastic cover or other standard controls. 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 is 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 Based on the septic drainfield location with relation to the existing and proposed topography, the drainfields are 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. This determination is based on the anticipated improvements of the project, engineering conclusions, and compliance with all recommendations provided in this report. 5.9 Driveway Considerations Considerations for the planned single family residence ingress/ egress include access from the existing roadway located a few hundred feet from the residence. It is understood that the driveway will be surfaced with gravel. It is recommended to keep the driveway grade at 14% or less, if at all possible for emergency vehicle access. Steeper grades, insufficient width, or other factors may require sprinklers in the home. Grades of 20% or less are common, but may be more difficult to traverse. Roadway Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 21 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County, Washington Fax: 360-2754789 December 10,2013 embankments and cuts should be limited to grades of no more than 2:1 (horizontal:vertical), especially if pavement is considered. However steeper side slopes of no steeper than 115:1 may be achieved for gravel roads, and will require more frequent maintenance than flatter side slopes. Road cuts or embankments should not exceed a vertical height of 10 feet for this Project. A 6- inch to 12-inch deep channel is recommended on the upslope side of the driveway, where the driveway runs nearly parallel with the slope. Channel stabilization with rip rap or check dams may be necessary for segments of the roadside channel exceeding a grade of 6%. If engineered fill is utilized for the driveway, it should meet the engineered fill materials and compaction requirements as presented earlier in this Report. Native subgrades beneath the engineered fill or the surface course material of the planned roadway shall be prepared to a depth of 8 inches. Subgrade preparation shall include the removal of trees, brush and other organic materials near the surface. The subgrade should be compacted to a depth of 8 inches. It is suggested to use a surface course material of at least 4 inches thick(6" preferred)that is angular (crushed) in shape.Non-crushed gravel or minimum gravel depths require additional maintenance over time.Pavement considerations will require additional engineering. Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 22 18920 E State Route 106 Belfair,Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County,Washington Fax: 360-275-4789 December 10,2013 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, Envirote h En ' eering Michael Staten,P.E. Geotechnical Engineer Envirotech Engineering Donald Porter Geotechnical Report PO Box 984 page 23 18920 E State Route 106 Belfair, Washington 98528 Parcel 12206-31-00070 Ph. 360-275-9374 Belfair,Mason County, Washington Fax:360-2754789 December 10,2013 APPENDIX A SITE PLAN 10 SCALE, 1 INCH = 150 FEET HOOD CANAL / 5 150 k� A T FENCE PER SION CONTROL �C3° TREAM (APPRX) BILIZED SAP STRUCTION ENTRANCE. SEE PSG / / OE OF REPORT CRITICAL IN / / CRITICAL SLOPE DRIVEWAY TO BE / / % OP OF CRITICAL, RECONSTRUCTED. / 40%+ SLOPE SEE REPORT / 0' BUILDING DO NOT // ,po SETBACK CRITICAL FROM TOP O CONSTRUCT FI]UNDAT NS IN 'TPI FILL P REPORT PROP ED GEOTECHNICAL SETBACK FROM H E STREAM. INCREASE SETBACK IF PRX) REQUIRED PER ECOLOGY. 20 VEGETATION REMOVAL IS NOT +`.K tiRo RESTRICTED ON SLOPES. HOWEVER, F DENUDED AREAS MUST BE REPLANTED PER REPORT. ROPERTY LINE SEPTIC LOCATIONS ARE UNKOWN, AND DO NOT POSE A THREAT TO SLOPE is STABILITY IF OUTSIDE OF SETBACKS REVEGETATE ALL DENUDED AREAS PER PERMANENT EROSION CONTROL IN REPORT / ZETBACKS OR / ' BUFFERS NOT REQUIRED FO / ASCENDING / SOILS, MEDIUM DENSE SILTY SAND SLOPES WITH GRAVEL (SM) OVERLYING ^ VERY DENSE GLACIAL TILL < OE OF CRITICAL SLOPE I � 189 FT / OP OF CRITICAL, 40%+ SLOPE PROJECT LOCATION- SINGLE FAMILY RESIDENCE NOTES GEOTECHNICAL REPORT L CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYER CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND 18920 SR 106 INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL REPORT. LEGEND HELFAIR, VASHINGTON 98`i28 2. BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR LOCATIONS PARCEL IM6-31-00070 OF SITE FEATURES THAT ARE SHOWN HERE, SUCH AS TOP OF SLOPES, TOE TEMPORARY ENGINEER, OF SLOOPES, WATER FEATURES, ETC_, WITH RELATION TO THE PROPERTY +f+EROSION CONTROL ENVIROTECH ENGINEERING LINES MUST BE VERIFIED BY THE OWNER, RECOW*ADATIONS IN THE PO BOX 984 GEOTECHNICAL REPORT PROVIDE SETBACKS, BUFFERS, DEPTHS, ETC. WITHSLOPE INDICATOR BELFAIR, WASHINGTON 98528 RELATION TO GEOLOGIC FEATURES, NOT PROPERTY LINES. THESE GEOLOGIC �D- EXISTING CONTOUR 360-275-9374 FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING PROPERTIES. TPI@ TEST PIT SITE PLAN APPENDIX B SOIL INFORMATION VERTICAL AND HURIZ13NTAL SCALE, SCALE- l RICH - 60 FEET PROPOSED HOUSE EXISTING FILL. EXISTING SEE REPORT GRADE MAINTAIN 1.5,1 MAX CUT GRADE UPSLOPE OF DRIVEWAY DRIVEWAY, SEE REPORT MAINTAIN 24 MAX FILL GRADE DOWNSLOPE OF DRIVEWAY SR 106 HOOD CANAL GLACIAL EPOSITS PE GEOTECHNICAL INVESTIGATIONS LANDSLIDE DEPOSITS PER MAPPED GEOLOGY SECTION A-A PROJECT LOCATION, SINGLE FAMILY RESIDENCE GE❑TECHNICAL REPORT 18920 E STATE ROUTE 106 PARCEL 12206-31-00070 MASON COUNTY, WASHINGTON ENGINEER, ENVIROTECH ENGINEERING PO BOX 984 BELFAIR, WASHINGTON 98528 360-275-9374 SOIL PROFILE TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: Upchurch Geotechnical Report DATE OF LOG: 11/24/2013 PROJECT NO: 13115 LOGGED BY: MCS CLIENT: John Upchurch EXCAVATOR: N/A LOCATION: Parcel 12206-31-00070 DRILL RIG: None Mason County, Washington ELEVATION: N/A INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A SOIL STRATA, STANDARD PENETRATIC DEPTH SAMPLERS USCS DESCRIPTION LL PI CUF AND TEST DATA DEPTH N 10 31 0 .. . .... ...... ... ... SM Brown, moist, loose to medium dense SILTY SAND with GRAVEL and some _ clay. Gravel is primarily well-graded and 1 subrounded. Sand is mostly fine and medium. Low plasticity. 2 3 Density increases with depth 4 Excavation terminated at approximately 4.0 feet 5 6 7 8 9 L10 No Groundwater Encountered ENVIROTECH ENGINEEF Tnis iniormation pertains oniy io this boring and shouid 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 Elevation: 50 to 800 feet Mean annual precipitation.25 to 60 inches Mean annual air temperature:48 to 52 degrees F Frost-free period: 180 to 220 days Map Unit Composition Alde;ivood and similar soils: 100 percent Description of Alderwood Setting Landform: Drainageways Parent material. Basal till with a component of volcanic ash Properties and qualities Slope: 15 to 30 percent Depth to restrictive feature: 24 to 32 inches to densic material Drainage class: Moderately well drained Capacity of the most limiting layer to transmit water(Ksat):Very low to moderately low(0.00 to 0.06 in/hr) Depth to water table:About 18 to 36 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Low (about 3.4 inches) Interpretive groups Farmland classification. Farmland of statewide importance Land capability(nonirrigated):4e Hydrologic Soil Group: C Typical profile 0 to 10 inches: Gravelly ashy loam 10 to 28 inches:Very gravelly loam 28 to 60 inches: Gravelly sandy loam Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 7, Jun 29, 2012 LSOK Natural Resources Web Soil Survey Y 3l1711U 13 Conservaborn Service National Cooperative Soil Survey Page 1 of 1 -WELI SCHEDULE CONTINUED LOGS,CASINOS, SCREENS, AQUIFERS (As necessary,insert Lcadlngs sod use[pace below for full record. Complete lop should be 0 recorded oa separate form for that purpose, but humenrary loss may be entered here) L (FEEn (FEET) � a6 /ob o ec�r Z O _ •s4 t., !o 41 - R E L 0 c a� L 0 c R e� 0 MISCELLANEOUS (On face of schedule add asterisks to identify topics amplified,ux same rope hesdmp here.) > C/s ti C i L.A/I �Q 2 C L 3 rC iz Cr Zar: �/.f. S. re c e J <n a� 0 10 a� _O Wa[a1NCT0[sA6D-SO ao-1 Sr]p APPENDIX C SLOPE STABILITY STABLE Slope Stability Analysis System New User Project Bennett Datafile: dynamic Bishop STABLE Version 9.03.00u Bishop xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx TITLE dynamic x xxxxxxxxxxxxxxxxxxxxxx xyrxxxx*xxxxxxxxxxxxxxxxxxxxxxx*xxxx UNITS (Metric/Imperial) = I x xxxxxxxxxxxxxxxxxxxx*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx GEOMETRY DEFINITION POINTS NO. X Y 1 0.000 0.000 2 50.000 -25.000 3 106.000 -50.000 4 150.000 -50.000 5 0.000 -5.000 6 50.000 -35.000 7 106.000 -52.000 8 150.000 -55.000 9 15.000 -7.500 10 21.320 -10.660 11 27.630 -13.820 12 33.950 -16.970 13 40.260 -20.130 14 46.580 -23.290 15 52.890 -26.290 16 59.210 -29.110 17 65.530 -31.930 18 71.840 -34.750 19 78.160 -37.570 20 84.470 -40.390 21 90.790 -43.210 22 97.110 -46.030 23 103.420 -48.850 24 109.740 -50.000 25 116.050 -50.000 26 122.370 -30.000 27 128.680 -50.000 28 135.000 -50.000 LINES Lo X Hi % SOIL 1 2 1 2 3 1 3 4 1 5 6 2 6 7 2 7 8 2 x.-r�r*:xxx*xxxx*x+xxxx*►:xx*xxxxxxxtx,rxxx*xxxxxxxxxxx**xxxxx STABLE Slope Stability Analysis System New User Project Bennett Datafile: dynamic Bishop SOIL NAME LINETYPE-PEN COHESION FRICTION UNIT WT. 1 Soil-1 CONTINUOUS-BLACK 200.00 24.0 130.000 2 Soil-2 CONTINUOUS-BLUE 200.00 38.0 138.000 x+xx++++*++++++++xxxx+x+++++*++++*+++++xxx+++++++xxxxxxxxx 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 x++x+++++x+++xxx+xx+++xx*+++x++++++++x++++++++x++xxxx+x+x+ SLIP DIRECTION (+/- X) = + xxx+xxxxxx++++++xxxx+++xxxxxxxxxxxx+xxx+++++++xxxxxxxxxxxx SLIP-CIRCLES AUTOMATIC Circle Centre Grid Extremities 120.000 15.000 * * 135.000 x x ++xx++*+xx++xxx 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 i5 Grid 8 Circles through point 16 Grid 9 Circles through point 17 1 . 0 0 1 _ 1 0 1 . 20 1 _ 3 0 1 . 40 1 _ 5 0 1 . 60 1 . 70 1 - 80 1 _ 9 0 2 . 00 _N 1� _ 16_ Proj c ct _ Bconrza tt Datafilc-- _ dynamic Analysis _ Bis2Zop 1 . 0 0 1 . 10 1 . 2 0 1 . 3 0 1 . 40 1 _ 5 O 1 . 60 1 _ '7 0 1 . 80 1 _ 90 2 . O 0 � I 1 . 7 4 4 Project _ Bennett Datafile static ,Analysis Bishop aTABL���002 M2 AmnoClat�m Ltd APPENDIX D EROSION CONTROL GEOTEXTILE FABRIC WRAP AROUND TRENCH TO AT LEAST ENTIRE BOTTOM OF TRENCH BEFORE PLACING GRAVEL 2'x2'x5' WOOD POST OR 12' DEEP, 8' WIDE TRENCH EQUIVALENT OR BETTER FILLED WITH 3/4' TO 1 1/2' 1 WASHED GRAVEL OR VEGETAT N 2.5 FT DIRECTION OF EXISTING iet STING WATER FLOW GROUND SURFACE � } I 25 FT SILT FENCE - CROSS SECTION N.T.S. 2'x2' WOOD POST (TYP) GEOTEXTILE FABRIC OR EQUIVALENT OR BETTER AND WIRE MESH @ 6 FT MAX. O.C. 6 FT � � 0.5 FT EXISTING GROUND SURFACE 2 12' DEEP, 8' WIDE TRENCH FILLED WITH 1FT 3/4' TO 1 1/2' 2.5 FT WASHED GRAVEL OR VEGE TIu _T BOTTOM EXTENTS OF GEOTEXTILE FABRIC SILT FENCE - DETAIL N.T.S. PROVIDE FULL WIDTH 3/4 IN TO 1 1/ PF INGRESS/EGRESS CRUSHED GRAVEL 20 FT PLACED AT 6 IN MINIMUM DEPTH WELL-DRAINED S❑ILS -0.02 IN/MIN FULL LENGTH R=25 FT MIN CL PROJECT/ OWNER/ LOCATION- ACCESS ROAD SINGLE FAMILY RESIDENCE STABILIZED CONSTRUCTION ENTRANCE J. UPCH ❑CHECHNICAL REPORT N.T.S. 19920 E STATE ROUTE 106 PARCEL 12206-31-00070 MASON COUNTY, WASHINGTON ENGINEER, ENVIROTECH ENGINEERING PO BOX 984 i BELFAIR, WASHINGTON 98528 360-275-9374 EROSION CONTROL P. 1 PERMANENT EROSION CONTROL NOTES NOTES, SEEDING FOR RAW SLOPES SHOULD THE TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES SHOWN ON [ESE PLANS PROVE TO BE INADEQUATE DURING CONSTRUCTION, THE CONTRACTOR 1. BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL HALL INSTALL ADDITIONAL EROSION AND SEDIMENT CONTROL FACILITIES. MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DD(ES, ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE SWALES, LEVEL SPREADERS AND SEDIMENT BASINS. NSPECTED DAILY AND IMMEDIATELY MAINTAINED, IF NECESSARY. 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE, 3. ALL ERDS113N AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT IN FOLLOWING SURFACE ROUGHENING. PERFORM ALL OPERATIONS ACCROS LACE UNTIL THE UPSLOPE AREAS HAVE BEEN PERMANENTLY STABILIZED. OR PERPENDICULAR TO THE SLOPE. 3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE EMPORARY EROSION CONTROL NOTES- APPLIED AT THE RATE OF 120 POUNDS PER ACRE. 4. SEED BEDS PLANTED BETWEEN MAY 1 AND OCTOBER 31 WILL ALL AREAS WHICH HAVE BEEN STRD'PED OF VEGETATION OR EXPERIENCED LAND REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO ISTURBING ACTIVITIES, AND WHERE NO FURTHER V❑RK IS ANTICIPATED FOR A FASTER AND PROTECT THE ROOT STRUCTURE RIOD EXCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE S SEED BEDS PLANTED BETWEEN NOVEMBER I AND APRIL 30, MMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING OR OTHER APPROVED ARMORING OF THE SEED BED WILL BE NECESSARY, (e g., ❑SION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR IBRASS SEEDING GEOTEXTILES, JUTE MAT, CLEAR PLASTIC COVERING). COW WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH 6. FERTILIZERS ARE M BE USED ACCORDING TO SUPPLIERS, PTEMBER. HOWEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST OF RECOMMENDATIONS. AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY OWNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING, NETTING ADJACENT TO WATER BODIES AND WETLANDS. IR OTHER APPROVED TREATMENT. USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION [HROUGH SEASON (MAY 1 THRU SEPTEMBER 30) — THE CLEARING OF LAND, INCLUDING THE CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE. OVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LIMITED TO Y AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE PROPORTIONS PURITY GERMINAT ERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR OTHERWISE DISTURBED NAME BY WEIGHT(%) (%) (X) NO LATER THAN SEPTEMBER 30 ❑F A GIVEN YEAR. UNLESS IMMEDIATE BILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL REDTOP (AGROSTIS ALBA) 10 92 90 AS CLEARED OR OTHERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED ANNUAL RYE (LOLTUM MULTIFLORUM) 40 98 90 THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, CHEWING FESUE 40 97 80 E DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED (FESTUCA RUBRA COMMUTATA) AN OF ACTION. UNLESS OTHERWISE APPROVED BY THE COUNTY, SEEDING, (JAMESTOWN, BANNER, SHADOW, KOKET) ERTILIZING AND MULCHING OF CLEARED OR ❑THERWISE DISTURRBED AREAS SHALL BE WHITE DUTCH CLOVER 10 % 90 ERFORMED DURING THE FOLLOWING PERIODS- MARCH 1 TO MAY 15, AND AUGUST 15 TO (TRIFOLIUM REPENS) TOBER 1. SEEDING AFTER OCTOBER i VILL BE DONE WHEN PHYSICAL COMPLETION IF THE PROJECT IS IMMINENT AND THE ENVIROMENTAL CONDITIONS ARE CONDUCIVE MULCHING 0 SATISFACTORY GROWTH. IN THE EVENT THAT PERANENT STABILIZATION IS NOT SSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHING, NETTING, 1. MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD ASTIC SHEETING, EROSION BLANKETS, ETC., MUST BE INSTALLED BY NO LATER THAN FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 1000 PTEMBER 30. POUNDS PER ACRE 2. MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES N THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT GREATER THAN 2d (H❑RIZONTAL,VERTICAL). CTIVITIES ARE DISCONTINUED FOR AT LEAST 4 CONSECUTIVE DAYS, THE 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN VNER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON. ALL D SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT AREAS REQUIRING MULCH SHALL BE COVERED BY NOVEMBER 1. AST ONCE EVERY WEEK, THE OWNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR HE MAINTENANCE AND REPAIR O ALL EROSION AN SEDIMENT CONTROL FACILITIES. TOPSOD_ING ET SEASON (OCTOBER 1 THRU APRIL 30) -- ON SITES WHERE UNINTERUPTED L TOPSOIL SHOULD BE USED FOR THIS PROJECT DUE TO HIGHLY 3INSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE DENSE EXPOSED SOILS. VAL OF EXISTING VEGETATION AND OTHER GROUND COVER, SHALL BE LIMITED 2. TOPSOIL SHOULD BE PLACED ON SLOPES NOT EXCEEDING 2-L ❑ AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HORS IN 3. STRIPPING AND STOCKPILING ❑N-SITE SOILS SHALL ONLY BE HE EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SE➢IMENT PERMITTED IF TOPSOIL IS FRIABLE AND LOAMY (LOAM, SANDY LOAM, RANSPORT ❑FF-SITE IS OBSERVED. SILT LOAM, SANDY CLAY LOAM, CLAY LOAM). L CLEARED OR DISTURBED AREAS SHALL RECEIVE APPROPRIATE PROTECTIVE 4. STRIPPING SHALL BE CONFINED TO THE IMMEDIATE CONSTRUCTION VER OR BE OTHERWISE STABILIZED, SUCH AS MULCHING, NETTING, PLASTIC AREAS. A FOUR TO SIX INCH STRIPPING DEPTH IS COMMON, BUT ING, EROSIONBLANKETS, FREE DRAINING MATERIAL, ETC., WITHIN 5 DAYS AFTER DEPTH MAY VARY DEFENDING ON THE PARTICULAR SOIL. ALL VI BEEN CLEARED OR ❑THERWISE DISTUARHED IF NOT BEING ACTIVELY WORKED, SURFACE RUNOFF C❑NTROL STRUCTURES SHALL BE IN PLACE BEFORE ILT FENCING, SEDIMENT TRAPS, SEDIMENT PONDS, ETC., WILL NOT HE VIEWED AS STRIPPING .LT COVER IN AND OF THEMSELVES IN THE EVENT THAT ANY LAND AREA NOT ING ACTIVELY VORKED 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 PROPRIATELY PROTECTED OR STABILIZED. STOCKPILE MANAGEMENT L STOCKPILE SHALL BE STABILIZED (WITH PLASTIC COVERING OR OTHER APPROVED DEVICO DAILY BETWEEN NN)VEMBER 1 AND MARCH 3L 2. IN ANY SEASON, SEDIMENT LEACHM FROM STOCK PILES MUST BE PREVENTED. 3. TOPSOIL SMALL NOT BE PLACED WHILE IN A FROZEN OR MUDDY CONDITION, WHEN THE SUBGRADE IS EXCESSIVELY WET, OR WHEN CONDITIONS EXIST THAT MAY OTHERWISE BE DETRIMENTAL TO PROPER GRADING OR PROPOSED SODDING OR SEEDING. 4. PREVIOUSLY ESTABLISHED GRADES W THE AREAS TO BE TIPS[DLED SHALL BE MAINTAINED ACCORDING TO THE APPROVED PLWRS. STABILIZED CONSTRUCTION ENTRANCE 1. MATERIAL SHALL BE 4 INCH TO 8 INCH QUARRY SPALLS (4 TO 6 INCH FOR RESIDENTIAL SINGLE FAMILY LOTS) AND MAY BE TOP-DRESSED WITH 1 INCH TO 3 INCH ROCK. (STATE STANDARD SPECIFICATIONS, SECTION 8-15.) 2. THE ROCK PAD SHALL BE AT LEAST 12 INCHES THICK AND 50 FEET LONG (20 FEET FOR SITES WITH LESS THAN 1 ACRE OF DISTURBED SOIL). WIDTH SHALL BE FULL WIDTH OF THE VEHICLE INGRESS AND EGRESS AREA. SMALLER PADS MAY BE APPROVED FOR SINGLE-FAMILY RESIDENTIAL AND SMALL COMMERCIAL SITES. 3. ADDITIONAL ROCK SHALL BE ADDED PERIODICALLY TO MAINTAIN PROPER FUNCTION OF THE PAD. 4. IF THE PAD DOES NOT ADEQUATELY REMOVE THE MUD FROM THE VEHICLE WHEELS, THE WHEELS SHALL BE HOSED OFF BEFORE THE VEHICLE ENTERS A PAVED STREET. THE WASHING SHALL BE DONE ON AN AREA COVERED WITH CRUSHED ROCK AND WASH WATER SHALL DRAIN TO A SEDIMENT RETENTION FACILITY OR THROUGH A SILT FENCE. 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 AC BARRIER TO AVOID USE OF JOINTS. IF JOINTS ARE NECESSARY, FILTER FABRIC SHALL BE SPLICED J. UPCHURCH OGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT 18920 E STATE ROUTE 106 TH ENDS TO THE POST. PARCEL 12206-31-WO70 STANDARD FILTER FABRIC SHALL BE FASTENED USING 1' STAPLES OR TIE WIRES (TOG RINGS) E 4 IN MASON COUNTY, WASHINGTON PACING. . POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED IN THE DETAILS ON THIS SHEET, AND ENGINEER RIVEN SECURELY INTO THE GROUND. ENVIROTECH ENGINEERING 15, WIRE MESH SHALL BE 8'X2'X14 GAUGE OR EOUIVILENT. THE WIRE MESH MAY BE ELIMINATED IF PO BOX 964 DffRA-STRENGTH FILTER FABRIC (MONOFILAMENT), AND CLOSER POST SPACING IS USED. BELFAIR, WASHINGTON 98528 A TRENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS O1N THIS SHEET ALONG THE LINE OF THE 360-275-9374 SST AFFEENCES PLRBE CATEDT OWNS O FROM THE CLEARING LIMITS OF THE PROJECT. EROSION CONTROL P. 2 GE0.2ft -000 uL] 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. Applicant's Name: �c-� l� Yl k VX 4 ir'C)-,.-- Permit#: 13M`L & -M)Sg2 ,/Parcel#: 1 Zq_©Le 3 -006 R �1 Date(s) of the Document(s) reviewed: Z�I L 1. (a) A discussi q-of general geologic conditions in the vicinity of the proposed development, OK? Comment: Ct (b) A discuss io of specific soil types OK? V Comment: I (c) A discussion,of ground water conditions OK? V Comment: '1 (d) A discussion the upslope geomorphology OK? Comment: q (e) A discussion the location of upland waterbodies and wetlands OK? Comment: (f) A discussion g# history of landslide activity in the vicinity, as available in the referenced maps and records OK? Comment: 100 1 1 2. A site plan that identifies the important development and geologic features. OK? k/ Comment: 9 3. Locations and logs of exploratory holes or probes. OK? t/- Comment: (,�,f' 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. OK? L/ Comment: W 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. OK? Comment: ? 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 Simplified Bishop'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. OK?VL Comment: 12 , (Le-t, 7. (a) Appropriate restrictions on placement of drainage features OK? L/ Comment: 2,' (b) Appropriate restrictions on placement of septic drain fields OK? V Comment: 11 (c) AppropriateLTstrictions on placement of compacted fills and footings. OK? Comment: 1 '71 1 41 Page 1 of 2 Form Effective June 2008 (d) Recommend buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes. OK? Comment: 2� (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes. OK? i% Comment: E. 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. OK? Comment: Zi 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. OK? Comment: (3 10. An analysis of both on-site and off-site impacts of the proposed development. OK? „� Comment: lT 11. Specifications of final development conditions such as, vegetative management, drainage, erosion control, and buffer widths. OK? ✓ Comment: '�67" A 12. Recommerdations for the preparation of structural mitigation or details of other proposed mitigation. OK? Comment:Comment: 21 13. A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of existing art proposed development on the site. OK? �� Comment: Are the Documents signed and stamped? .V( By whom? kit D 1n License#: �{ ��rj License type: FIRST REVIEW Approved ❑ Need more info. If not approved, what is the next action/recommendation for further action? Reviewed by LTime spent in review: 1 �r SECOND REVIEW/ UPDATE ❑ Approved ❑ Need more info. Reviewed by , on . Time spent in second review: THIRD REVIEW/UPDATE ❑ Approved ❑ Need more info. Reviewed by , on . Time spent in third review: Disclaimer.- Mason County does not certify the quality of the work done in this Geotechnical Report. Page 2 of 2 Form Effective June 2008