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Home My WebLink AboutGEO2014-00033 for BLD2014-00625 - GEO Geological Review - 1/23/2013 =33 4;i-1 td 06 H- 00(aa5 PLANNING JUL, I , 20% 426 W. CEDAR S'e Geotechnical Report for Hankinson Single Family Residence and Detached Garage 220 NE Steelhead Drive S, Belfair Parcel No. 22325-44-92002 Mason County, Washington January 23, 2013 Project#1306 Prepared For: Robert Hankinson ti CLYL) 1504 Bertha Avenue G�.Pti F WAsy, ST9T Bremerton, Washington 98312 � Prepared By: Envirotech Engineering °�� F ST1- PO Box 984 SS�ONALEI� Belfair, Washington 98528 Phone: 360-275-9374 Fax: 360-275-4789 MASON COUNTY DEPARTMENT OF COMMUNITY DEVELOPMENT Planning Division P O Box 279, Shelton, WA 98584 (360)427-9670 Geotechnical ReportReview Acceptance Letter August 22, 2014 ROBERT W HANKINSON JR 1504 BERTHAAVE NW BREMERTON WA 98312 Case No.: GE02014-00033 Parcel No.: 223254492002 Proiect Description: GEO REPORT FOR BLD2014-00625 SFR The Geotechnical Report for ROBERT HANKINSON JR has been received and reviewed by the Planning Department. The report was prepared by M. Staten dated 1/23/2014. Based on the certification provided by the licensed engineer/geologist, the referenced Geotechnical Report was prepared in general accordance with the requirements in the Mason County Resource Ordinance, Landslide Hazard Areas 17.01.100.E.5. Mason County considers the review valid until such time as scope of project, site conditions, and/or regulations change. Should the scope of work, site conditions, and/or regulations change after the original review, then an addendum from the original author of the report may be required to address these changes. The report would only be re-reviewed if a permit for development were submitted after these changes occur. Mason County does not certify the quality of the work done in this Geotechnical Report. Please contact me at (360) 427-9670, ext. 365 if you have questions. Sincerely, Allan Borden Land Use Planner Mason County Planning Department Comments: 8/22/2014 Page 1 of 1 GE02014-00033 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: r r Permit# V�v �t/C �� ,,ii Parcel# q�2�ZS `L 1 Date(s) of the occuBGD ment(s)reviewed- — (1) (a)A discussion of general geologic conditions in the vicinity of the proposed development, OK? Comment: (b) A discussion of specific soil types OK? Comment: ..(c) A discussion of ground water conditions. OK? Comment: (d) A discussion of the upslope geornorp.hology OK? Comment: (e) A discussion of the location of upland waterbodies and wetlands OK? Comment: ; (f) A discussion of historyof landslide activity in the activity in the.vicinity; as available in the referenced maps and records OK?Vsd omment: (2) A sitick identifies the important development and geologic features. OK? omment: (3) Loca logs of exploratory holes or probes. OK? Comment: (4) The area of t proposed development, the boundaries of the hazard, and associated buffers and setbacks all be delineated(top,both sides, and toe)on a geologic map of the site. OK? Comment: (5) A minimum one cross section at a scale which adequately depicts the subsurface profile, and which in ora#es the details of proposed grade changes. OK? Comment: (6) A desc iption 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 Bi op's Method of Circles. The minimum static safety factor is 1.5, the minimum seismic sa)6ty factor is 1.1.and the quasi-static analysis coeffients should be a value of 0.15. OK? V Comment: (7) (a)Appropyiate restrictions on placement of drainage features OK? VV Comment: (b) Appro Hate restrictions on placement of septic drain fields OK? omment: (c) Approp ate 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 ` OK? r/Comment: (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other lopes on the property. OK? Comment: (8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies veg tation to be removed, a schedule for vegetation removal and replanting, and the method of v getation removal. OK? Comment: (9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies th specific mitigating measures to be implemented during construction to protect the slope fro erosion, landslides and harmful construction methods. OK? C mment: (10) An analysis f 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 co ol, and buffer widths. OK? Comment: (12) Recommen/dations for the preparation of structural mitigation or details of other proposed mitigation/ OK? V Comment: (13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of existing and proposed development on the site. Comment: Are the Documents signed and st mp d? . Type and #of License: If.not approved, what is the next action/recommendatiori for furthe�. action?' 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 Mason County Department of Community Deveiopt Ont �iiFf'lS'rr i ri;ecitiist For a Geoiecnnical Repot t instructions: This checklist must be submitted with a Ge-otechnical Report and completed, signed, and stamred b;y the licensed professional(s)who prepared the Geoiechnical Report for review by fAson County pursuant to the f:rason Gounty R'asr,urr,e U_ arrce_ a=;jem Ijbiji5d to be not applicable, the report should explain the basis for the conchision_ L Applicant/Ok,v i �ner 0 �I l &'Vi vt q' r arcel# Z 252 5 ZOv Z site Address `Z Z y ee / �r,V, S, r �5-e �'( (1) (a)A discussion of general_c edlogic conditions in the vicinity of the proposed development. Located on page(s) `J (b) A discussivr,of specific SGie types Located on pages) (c) A discussion of ground water conditions Located on rages) 7 (d) A discussion of the upslope geGMorphology i_u(;aied on page(s) 3 (e) A discussion.of fide!ocatior:of upland v:atefiodies and wetlands Located on page(s) ( A uiscussiori Of iiist-ory or iancstioe activity in the activity in the vicinity,as available in the referenced maps and records Locarlcd or. pagers' �� 9 (2) A site plan,.&,hich identifies the int rant devel�j nt and geologic features. Located on Mao(s) � (�9p (3) Locations and logs of exploratory holes or probes_ (4) The area of the proposed development, the boundaries of the hazard, and associated buffers and setbacks shall be delineated(Op; bb th sides,and toe)on a'geologic map of the site. Located o1 i Maps) S,'� / c (5) A minin'iFum of one cross Sec`�on at a sca!e which adequately depicts the subsurface profile, and which incorporates the details of pr /^sec,grade changes- :-i)1 f Itfiat..i� j �t/ P�� static and s ismic loalnng c*! e 6 A dwMdpt en grid:°wcil'fc ,slope sf3t=itm s,Ral ys yes performed !r be. conditions.Analysis should examine worst case failures-Tire analysis should include the. C ;tFed 13isi iap'S 1vei tad of--- a eas_The n-iulE nw-,i sba is saf aty facia is 1_5,tha minil11ff n seismic sa,eiy,factor is 1_1.and the quasi-static analysis coe`fients should be a va-We of 0-15. Located on page(., ;�� C-#2, C-- (!) (a).4pnropriate r estrictions on placement of drainagefeatures Located on page(s) /.- (b) Appropriato -ast^vtions on placement of sepfic crag:fields Located on page(s) 7 (c) . fpr,priaie restr ictions on lacerneni of compacted fills and footings Located on pages) Z / Page 1 of 2 Form Effective June 2008 Jisclaicmer. fwason Countv does not certiN the-1ality gf the!pork done in tf:is Geot^c 12-i—I F--JIJi. (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes on the properiy- Located on pages) (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other siopes on the property. Located on page(s) / (8) kecoinmendations for the preparation of a detailed clearing and grading pith"i w;,i6'c identi ies vegetation to be removed, a schedule for vegetation removal and repianting, and the method of vegetation removal. Located on page(s) / (9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies the speck mitigating measures to be implemented during construction to protect the slope from erosion, landslides and'harmful construction methods_ Located on page(s) /P (-icy) An analysis of both on-site and off-site impacts of the proposed development. Located on page(s) (�i) Specifications of final development conditions such as, vegetative manage„ieni, drainage, erosion control, and buff widths_ Located on pages) - (92) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. Located on page(s) /V (13) A site map drawn to scale showing the p[operty.boundaries,scale,north arrow,and the!oration and nature of existing and proposed deveJ / opmer i on the site. �Lcct�ee-:oi-I jriap(S) 5;,, i, C `'I C_1_4` hereby cerffi(unuer penalty of perjury 41at i am a cmi erginear licensed in the State of Washington with specialized knowledge of ge;3te ni Jgei3fogi i a-iginwring or a geologist or a-ighearing gcawgist tioarsc d in Vie State of Report, dated O(h 2 20 ,ai:d entified G I C-I,A r c n� - D-e�ix cV1�t ,!aqe, cneeis ah me t via_-neil�s of ittle Mason 001-I Bty Resource O Liman ce, de hazard 8ecgon.is ccmgtete and true,that She assessment demonsirates conclusively that t1he risks posed by the landslide hazard can be rnilgated t,nmugh the inciudea geollac—'namcm Gesige ariu gja:aH hammer s am e"ZiggateG ne s:out a manner as io pr avert:�_ f to proipa 1:and p?.bH_r e2!th and s a,eb:_6C - : 43Gin 045 f #Y v `S'jFJNIALF� Page 2 of 2 Form Effective June 2008 S alr:-: _. Mascri County dees riot certlfV_ the^i1alify of the wog -,erne in this TABLE OF CONTENTS 1.0 INTRODUCTION..................................................................................................................................1 1.1 PROJECT INFORMATION.....................................................................................................................1 1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK.........................................................................2 2.0 SURFACE CONDITIONS....................................................................................................................3 2.1 GENERAL OBSERVATIONS..................................................................................................................3 2.2 TOPOGRAPHY.........................................................................................................•••••........................3 2.2.1 Upslope Geomorphology.............................................................................................................3 2.3 SURFACE DRAINAGE...........................................................................................................................3 2.3.1 Upslope Water Bodies.................................................................................................................4 2.4 SLOPE AND EROSION OBSERVATIONS................................................................................................4 3.0 SUBSURFACE INVESTIGATION......................................................................................................5 3.1 FIELD METHODS,SAMPLING AND FIELD TESTING............................................................................5 3.2 GENERAL GEOLOGIC CONDITIONS....................................................................................................5 3.3 SPECIFIC SUBSURFACE CONDITIONS..................................................................................................6 3 3.1 Groundwater...............................................................................................................................7 4.0 ENGINEERING ANALYSES AND CONCLUSIONS..............................................................»»....8 4.1 SLOPE STABILITY................................................................................................................................8 4.1.1 Slope Stability Analysis...............................................................................................................9 4.1.2 Slope Stability Assessment........................................................................................................10 4.2 EROSION............................................................................................................................................10 4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION.............................................................................11 4 3.1 Liquefaction..............................................................................................................................11 4.4 LATERAL EARTH PRESSURES...........................................................................................................11 4.5 ON-SITE AND OFF-SITE IMPACTS.....................................................................................................11 5.0 ENGINEERING RECOMMENDATIONS..........»..»..............»....»........»»»..»»»......»...»»»»»».».12 5.1 BUILDING FOUNDATION RECOMMENDATIONS................................................................................12 5.1.1 Bearing Capacity.......................................................................................................................12 5.1.2 Settlement..................................................................................................................................13 5.1.3 Concrete Slabs-on-Grade..........................................................................................................13 5.2 EARTHwoRK CONSTRUCTION RECOMMENDATIONS......................................................................13 5.2.1 Excavation.................................................................................................................................13 5.2.2 Placement and Compaction of Native Soils and Engineered Fill...........................................14 5.2.3 Retaining Wall Backfill............................................................................................................1 S 5.Z4 Wet Weather Considerations....................................................................................................15 53 BUILDING AND FOOTING SETBACKS.................................................................................................15 5.4 SURFACE AND SUBSURFACE DRAINAGE...........................................................................................15 5.5 VEGETATION BUFFER AND CONSIDERATIONS.................................................................................16 5.6 TEMPORARY AND PERMANENT EROSION CONTROL.......................................................................16 5.7 SEPTIC DRAINFIELDS........................................................................................................................17 6.0 CLOSURE............................................................................................................................................is Appendix A-Site Plan Appendix B-Soil Information(Soil Profile;Soil Logs;Well Reports) Appendix C-Slope Stability Input&Output Appendix D—Erosion Control i 1.0 INTRODUCTION Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a planned single family residence and detached garage located at 220 Steelhead Drive S, identified as parcel number 22325-44-92002, Belfair, 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, Robert Hankinson, in support of the proposed development as detailed below. The proposed development, as provided herein, and the surrounding area is identified in this report as the Project. An initial geotechnical evaluation of the Project was conducted by Envirotech on January 16, 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. Existing development consists of a driveway and cleared building pads. The planned development is a single family residence, detached garage, septic drainfield, and other ancillary features typical of this type of development. Foundation construction is expected to consist of continuous strip footings with concrete slabs-on-grade or stem walls. Approximate building footprint and other proposed features with relation to existing site conditions are illustrated on the Site Map provided in Appendix A of this report. Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 1 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 1.2 Purpose of Investigation and Scope of Work The purpose of this geotechnical investigation is to assess geological hazards, and evaluate the Project in order to provide geotechnical recommendations that should be implemented during development. The investigation included characterizing the general Project surface and subsurface conditions, and evaluating the suitability of the soils to support the planned site activities. In order to fulfill the purpose of investigation, the geotechnical program completed for the proposed improvements of the Project include: • Review project 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. RecNNooNOR C t,sNO / `.. .�._. 25 FIE UM OR Project T23NRZW M[1/YA LN s 36 p NISMATTIOMOR Vicinity Map from Mason County Website Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 2 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the Project was gathered on January 16,2013 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 Steelhead Drive S, an existing unpaved roadway prior to the driveway. The driveway mostly cuts into the hillside with some sidecast as it meanders up the hillside. The Project is partially developed land as previously mentioned. Beyond the property, rural residential development exists. Vegetation on and near the Project consists primarily of secondary growth firs,cedars, huckleberry,and other trees and shrubbery common to this area of the Pacific Northwest. Mission Creek is located about 50 to 100 feet east of the access road. 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 about 25 feet to the east of the planned development. The maximum critical slope is approximately 50%, but average grades are near 43%with a vertical relief of approximately 100 feet. Ascending grades are generally located to the west of the planned development. These slopes are relatively i t wi in f n 1 °minor within 300 feet of the Protect,with o apparent slope grades of at east 25/o. 2.2.1 Upslope Geomorphology The upland area of the property is situated on a hillside and ridge of glacial origin. 23 Surface Drainage Stormwater runoff originating upslope from the anticipated development appears to primarily sheet flow, and is expected to be minimal to moderate.Runoff originating upslope of the property is mostly diverted away from the property by accommodating topography and soils with very high infiltration rates. Mission Creek periodically floods and erodes the flooding limits, but will not affect the proposed development. Excessive scour, erosion or other indications of past drainage problems were not observed within the immediate vicinity of the planned development. Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 3 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 2.3.1 Upslope Water Bodies There are no apparent water bodies or wetlands located upslope from the planned 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. Other than problems associated with Mission Creek and slight surface movements due to the driveway cuts, 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. a I. s r•••� -•� !rr' _ H � � � r Aerial Photo from Mason County Website Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 4 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 3.0 SUBSURFACE INVESTIGATION Information on subsurface conditions pertaining to the Project was primarily gathered on January 16,2013 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 within test pits extending to depths of up to 6.5 feet below the existing ground surface,and observing cut slopes of up to 4 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 24 inches, and dense soils from 24 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, Katelin Alldritt, Nicholas J. Hehemann, Isablle Y. Sarikhan, and Robert L.Logan,July 2009,provides the following caption(s)for the project area: Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 5 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 Vashon till—Unsorted,tnstratified(but locally banded)nix of clay,silt, sand,and gravel:typically supported by a sandy matrix:mostly gray but locally ranging to tan,light brown.or orange:typically unweathered: lodgment till compact,with well-developed facies resembling concrete. but near the surface commionly lrackly and(or)looser and covered by 1 to 6 ft of loose ablation till:deposited directly by glacial ice and commonly includes clasts or chumps plucked from underlying units.Clasts are commonly striated and faceted,with angular or rounded edges.Boulders are generally sparse within the till but large(erratic)boulders of plutonic or metamorphic rock are common on till surfaces.Some exposures include interbands and lenses of sand and gravel,locally with shears and joints. Till forms a locally patchy and seemingly randomly distributed cover rip to a several tens of feet thick.with a thickness of 5 to 20 ft most contmon.It typically dominates.but is also locally discontinuous on.fluted surfaces, with individual drunilins measuring 0.1 to 0.3 ni wide by 0.8 to 1.3 ri long and the long axis aligned with the direction of ice flow.Till typically is in sharp.unconfortuable contact with underlying units,most commonly advance outwash(unit Qga and subunit). Unit Qgt lies stratigraphically below unit Qgo.It may include unrecognized exposures of older till.A map boundary mismatch between tout Qgt on this map and unit Qgos on the Vauglm quadrangle to the south(Logan and Walsh.2007)may have resulted from a map-production error in the northwest conner of the Vaughn map(Josh Logan.Wash.Divu.of Geology and Earth Resources. oral conmmn..2009). 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 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 6.5 feet of natural ground were observed to be moist, brown poorly graded sand with gravel (SP) and traces of silt. Soils below the observed depth are expected to be similar or transition into a silty sand (SM). Hardpan could be located at depths of 20 to 40 feet below the existing ground surface. The relative densities of the soil within selected test pits are provided above in Section 3.1. Expanded and specific subsurface descriptions, other than what is provided in this section, are provided in the soil logs located in Appendix B of this report. According to the "Soil Survey of Mason County," by the United States Department of Agriculture, Soil Conservation Service, the predominant site soils are described as Everett Gravelly Sandy Loam, Ek,with 15%-30%slopes.The soil designations are depicted in the aerial photograph below,and descriptions are provided in Appendix B of this report. Envirotech Engineering Hankinson Geotechmical Report PO Box 984 page 6 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-275-4789 January 23,2013 i� '� �#'�i ,tee• '��C ; A �M � h a t � f i Y 25 - , Y T23N R2W it ; 38 `: s Soil Survey From USDA Natural Resources Conservation Service 3.3.1 Groundwater From the water well report(s)and knowledge of the general area, permanent groundwater is at least 100 feet directly below the property at the building pad location. 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 during some or all wet seasons. Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 7 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 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 Resource Map from the Washington State Department of Natural Resources (DNR), the Project is within terrain labeled `highly unstable' relating to soils. A Resource Map from the DNR Forest Practices Application Review System is provided below: Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 8 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 2 24 Z L 1708640 17 1708544 F Y N L r�r + 90 26 25 o ITW522 7085 '�jy170E626 Project r� 7 + +70 4 U 1 y� m k a 31 h Resource Map from Washington State Department of Natural Resources Website 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 30 feet soil depth Soil unit weight: 120 pcf Angle of internal friction: 34 degrees Cohesion: 0 psf Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 9 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 Soils below 30 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 1.7 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 1.9 and 1.1, respectively. See the slope stability information in Appendix C for a depiction of input parameters and example of outputs. 4.1.2 Slope Stability Assessment DNR did not indicate previous landslide activity near the Project. Mapped slope conditions,as delineated by the Department of 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. 4.2 Erosion Based on the USCS description of the Project soils, the surface soils are considered low to moderately erodible. According to the Resource Map from the Washington State DNR, as provided above, the Project is within terrain labeled `highly erodible.' This Project is not within an erosion hazard area as defined by the MCRO.Erosion hazard areas are those with USDA SCS designations of River Wash (Ra), Coastal Beaches (Cg), Alderwood Gravelly Sandy Loam on slopes 15% or greater (Ac and Ad), Cloquallum Silt Loam on slopes 15% or greater (Cd), Harstine Gravelly Sandy Loam on slopes 15% or greater (Hb), and Kitsap Silt Loam on slopes 15%or greater(Kc). It is our opinion that minor erosion control recommendations provided in this report is sufficient for the development of this Project, and additional 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. Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 10 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 4.3 Seismic Considerations and Liquefaction 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. 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 5 miles to the south of this Project. This information is based on the USGS Quaternary Fault and Fold Database for the United States. 4.3.1 Liquefaction The potential for liquefaction is believed to be low for this Project. This is based, in part, on the subsurface conditions such as soil characteristics and the lack of a permanent shallow water table. Subgrade characteristics that particularly contribute to problems caused from liquefaction include submerged, confined, poorly-graded granular soils (i.e. gravel, sand, silt).Although gravel-and silt-sized soil particles could be problematic,fine and medium grained sands are typically subjected to these types of seismic hazards. No significant saturated sand stratifications are anticipated to be within the upper 50 feet of the subsoil for this Project. 4.4 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. 4.5 On-Site and Of 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 Hankinson Geotechnical Report PO Box 984 page 11 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 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 16 inches shall be placed at a minimum of 18 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 Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 12 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 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 Hankinson Geotechnical Report PO Box 984 page 13 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax: 360-2754789 January 23,2013 I I 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. F❑❑TING COMPACTED NATIVE S❑ILS OR ENGINEERED 1 FILL 1 UNDISTURBED SUBGRAIV 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 Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 14 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an engineer. 5.23 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 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. 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 25 feet footing setback from the face of the nearby descending slopes exceeding 40%. See the figure below and the Site Plan in Appendix A for an illustration of the setbacks. STRUCTURE TOP OF SLOPE SLOPE FACE i 25 FT MIN FOOTING The required setbacks may be reduced, if necessary. The setback may be decreased by extending the foundation an additional 2 feet in depth below the ground surface for every 5 feet of setback reduction. Other mitigation techniques may be utilized in order to reduce the required setback, 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 Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 15 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-275-4789 January 23,2013 l 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 beyond the toe of the steep 40%slope or within the area designated on the site plan in Appendix A of this report. Roof and foundation drains may share the same tightline if a backflow preventor is utilized to prevent roof water from entering the foundation area. 5.5 Vegetation Buffer and Considerations Vegetation is an excellent measure to minimize surficial slope movements and erosion on slope faces and exposed surfaces. By removing trees, the root strength is decreased over time, thereby lowering the `apparent' cohesion of the soil. Transpiration is decreased, which results in additional groundwater, increased pore water pressure and less cohesion/ friction of the soil particles. Stormwater runoff also increases, and, fewer plants will create less absorption of the force from raindrops,thereby creating the potential for erosion hazards. For this project, we believe that a detailed clearing and grading plan is not warranted, and basic vegetation management practices should be adhered to.Vegetation shall not be removed from the face of the critical slope or within a distance of 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, silt fencing, intercepting swales, berms, straw bales, plastic cover or other standard controls. Although other controls may be used, if adequate, silt fencing is presented in this report as the first choice for temporary erosion control.Any erosion control should be located down-slope and beyond the limits of construction and clearing of vegetation where surface water is expected to flow. If the loss of sediments appears to be greater than expected, or erosion control measures are not functioning as needed, additional measures must be implemented immediately. See Appendix D for sketches and general notes regarding selected erosion control measures. The Site Map in Appendix A depicts the recommended locations for erosion control facilities to be installed,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 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 Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 16 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-275-4789 January 23,2013 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 The approximate location of the proposed septic drainfield is presented on the Site Plan in Appendix A of this report.Based on the septic drainfield location with relation to the existing and proposed topography, the drainfields are not expected to adversely influence critical slopes. This is also based on compliance with all recommendations in this report. Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 17 220 Steelhead Drive S Belfair,Washington 98528 Parcel 2232544-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 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, Envirotegh Engineering V Michael Staten,P.E. Geotechnical Engineer Envirotech Engineering Hankinson Geotechnical Report PO Box 984 page 18 220 Steelhead Drive S Belfair,Washington 98528 Parcel 22325-44-92002 Ph. 360-275-9374 Mason County,Washington Fax:360-2754789 January 23,2013 APPENDIX A SITE PLAN SCALE- 1 INCH = 100 FEET s 0 25 50 100 fr 70' ' TOPI OF 40X+ RME I 1 SEPTIC 1 ADI�LD AREA P SILT'FENCE 0q \ TP1 1 OTHER APPROPRIATE ' EROSION CONTROL fDC 4� SE SIDEN I5FT VEGETATION W Ci BUFFER FROM TOP AND SIDE OF j 1 CRITICAL SLOPE El X SIDS OF 40X+ SLE PE < RX) H ♦ z 25F CONSTRUCTED SE M \ SIDE OF d SLOPE b ♦ �' G EXISTING \ \ PADS BUILDING \ \ FUTURE \ H GARAGE \ _ SHALL n MAI TAIN TRUCTIOI MID \ VEGETA SETBACKS PER STING AY THE RESIDENCE \ SOILS' MEDIUM DENSE SAND V1TH GRA CSP) OVERL VERY DENSE GLACIA TILL -480' NOTES. PROJECT/ OWNER/ LOCATIONS 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. ROBERT HANKINSON CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND 220 STEELHEAD DRIVE S INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL LEGEND PARCEL 22325-44-92002 REPORT. MASON COUNTY WASHINGTON 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 SLOOPES, 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 -SD-- EXISTING CONTOUR FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING TP1 TEST PIT SITE PLAN PROPERTIES. APPENDIX B SOIL INFORMATION VERTICAL AND HORIZONTAL SCALE- I INCH s 40 FEET 40 PROPOSED HOUSE MEDIUM DENSE TO DENSE POORLY GRADED SAND (SP) 43i EXISTING GRADE AND PROPOSED GRADE DENSE GLACIAL TILL PROJECT/ OWNER/ LOCATION, SINGLE FAMILY RESIDENCE GE❑TECHNICAL REPORT R HANKINSON SECTION A-A PARCEL 22325-44-92002 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, S❑IL PROFILE TEST PIT LOG TEST PIT NUMBER TP-1 PROJECT: Hankinson Geotechnical Report DATE OF LOG: 1/16/2013 PROJECT NO: 1306 LOGGED BY: MCS CLIENT: Robert Hankinson EXCAVATOR: N/A LOCATION: Parcel 22325-44-92002 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 SP Brown, moist, loose to medium dense POORLY GRADED SAND with GRAVEL _ and trace of fines. Gravel is primarily fine 1 and subangular. Sand is mostly medium. Non-plastic. Z ., ., 3 4 Increasing density with depth 5 6 �.L Excavation terminated at approximately 7 6.5 feet 8 9 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:Everett gravelly sandy loam, 15 to 30 percent slopes— Mason County,Washington Mason County, Washington Ek—Everett gravelly sandy loam, 15 to 30 percent slopes Map Unit Setting Elevation: 50 to 500 feet Mean annual precipitation: 55 to 90 inches Mean annual air temperature:48 to 50 degrees F Frost-free period: 160 to 180 days Map Unit Composition Everett and similar soils: 100 percent Description of Everett Setting Landform: Terraces Parent material: Glacial outwash Properties and qualities Slope: 15 to 30 percent Depth to restrictive feature: 20 to 40 inches to strongly contrasting textural stratification Drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water(Ksat): High(1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity:Very low(about 1.2 inches) Interpretive groups Farmland classification: Farmland of statewide importance Land capability(nonirrigated):4e Hydrologic Soil Group:A Typical profile 0 to 7 inches: Gravelly ashy sandy loam 7 to 21 inches: Extremely gravelly sand 21 to 60 inches:Very gravelly sand Data Source Information Soil Survey Area: Mason County, Washington Survey Area Data: Version 7, Jun 29, 2012 Natural Resources Web Soil Survey 1/23/2013 �� Conservation Service National Cooperative Soil Survey Page 1 of 1 tr L 0 in WATER WELL REPORT CL cuRRENT Original&I"copy-Ecology,2nd copy-owner,Yd copy-driller Notice of Intent No. W 249616 e'c'oTti'c`r Unique Ecology Well ID Tag No. d9KT t t tta B 4) Construction/Decommission ("x"in circle) ��.�t v02 z )0 Construction Water Right Permit No. H O Decommission ORIGINAL INSTALLATION Notice Property Owner Name Michael Polo r G of Intent Number -! Well Street Address Steelhead Dr- PROPOSED USE: EkDomestic ❑ Industrial ❑ Municipal 0 ❑ DeWater ❑ Irrigation ❑ Tut Well ❑ Other City Belfair County Mason C Location SEI/4-1/4 SE 1/4 Sec� Twn23 R_2W EwM or circle 0 TYPE OF WORK: Owner's number of well(if more than one) one wwM .6.4 1XNew well ❑ Reconditioned Method ❑ Dug ❑ Bored ❑ Dnven ❑ Deepened IR Cable ❑ Rotary ❑ Jetted Lat/Long(s,t,r Lat Deg Lat Min/See DIMENSIONS: Diameter of well 6 inches,drilled_ 7 ft. Still REQUIRED) Long Deg Long Min/Sec aF, Depth ofcompleted well 57 ft, r CONSTRUCTION DETAILS Tax Parcel NO. Casing I*Welded Diam.from ft.to ft. C Installed: ❑ Liner installed Diam from ft.to ft. CONSTRUCTION OR DECOMMISSION PROCEDURE ❑ Threaded Diam.from ft.to ft- L Perforations: ❑ Yes f1 No Formation: Describe by color,character,size of material and structure,and the kind and nature of the material in each stratum penetrated,with at least one entry for each change of _0 0 Type of perforator used information USE ADDITIONAL SHEETS IF NECESSARY. Q SIZE of perfs in,by________:_in and no.of perfs from_It to fl MATERIAL FROM TO Screens: Yes ❑ No :W K-Pac Location t�cO Manufacturer's Name Johnson Brown- Brown sand & gravel 0 3 Type Model No. l4 Dram Sot stu from _R.to_ ft Diam.—5 Slot size 20---from 52 ft.to — r—ft. BrOWfi till SGravel/Filter packed: ❑ Yes ❑ No ❑ Size ofgravel/sand yJ Materials placed from ft to ft. Browri Sand Surface Seal: jQ Yes ❑ No To what depth? 18 ft. Material used in seal Betc)n;t;Q iDid any strata contain unusable water? ❑ Yes No L Type of water? Depth of strata Method of sealing strata off PUMP: Manufacturer's Name 4 Type H.P. WATER LEVELS: Land-surface elevation above mean sea level ft. Static level 26 . ft.below top of wdl Date OArtesian pressure Ibs per square inch Date Artesian water is controlled by � (cap,valve etc. WELL TESTS: Drawdown is amount water level is lowered below static level 0 Was a pump test made? ❑ Yes JO No If yes,by whom? 0 Yield __gal./min.with ft.dawdown after hrs. V Yield: al./min.with ft.dawdown after hrs. U Yield. gal/min.with fl dawdown afler firs Recovery data(time taken as zero whenpump turned qff)(water level measured from well 0 mp to water level) — -- t Time Water Level Time Water Level Time Water Level - ti L Date of test LBailer test _15al/min.with 1 ft drawdown after_7 hrs W-aghitj11on sf I Airtest gal./min.with stem set at ft.for hrs. Pepavmv= Artesian flow g.p.m. Date _____ Gl Temperature of water Was a chemical analysis made? ❑ Yes JV No Start Date 1 f 1 9.10a_ Completed Date 111 R Ing WELL CONSTRUCTION CERTIFICATION: I constructed and/or accept responsibility for construction of this well,and its compliance with all Washington well construction standards. Materials used and the information reported above are true to my best knowledge and belief. EkDriller ❑Engineer ❑Trainee Nam rint) Drilling Company--L)3V1S Dri I I ing Driller/Engineer(rrainee Signature Address 340 NE Day1S Farm Rr3- Driller or trainee License No. 1706 City,state,Zip Belfair, WA 98528 If TRAINEE, Contractor's Driller's Licensed No. Registration No. DAVISDI1 1 OOA Date Jan Qg Driller's Signature Ecology is an Equal Opportunity Employer 11 ECY 050-1-20(Rev 3/05) The Department of Ecology does NOT warranty the Data and/or Information on this Well Report. APPENDIX C SLOPE STABILITY I STABLE Slope Stability Analysis System New User Project Hankinson Datafile : Dynamic Bishop STABLE Version 9.03.00u Bishop TITLE Dynamic UNITS (Metric/Imperial) = I GEOMETRY DEFINITION POINTS NO. X Y 1 0.000 0.000 2 100.000 -10.000 3 350.000 -110.000 4 400.000 -115.000 5 0.000 -30.000 6 100.000 -40.000 7 350.000 -115.000 8 400.000 -120.000 9 40.000 -4.000 10 56.840 -5.680 it 73.680 -7.370 12 90.530 -9.050 13 107.370 -12.950 14 124.210 -19.680 15 141.050 -26.420 16 157.890 -33.160 17 174.740 -39.890 18 191.580 -46.630 19 208.420 -53.370 20 225.260 -60.110 21 242.110 -66.840 22 258.950 -73.580 23 275.790 -80.320 24 292.630 -87.050 25 309.470 -93.790 26 326.320 -100.530 27 343.160 -107.260 28 360.000 -111.000 LINES Lo X Hi X SOIL 1 2 1 2 3 1 3 4 1 5 6 2 6 7 2 7 8 2 SOILS STABLE Slope Stability Analysis System New User Project Hankinson Datafile: Dynamic Bishop SOIL NAME LINETYPE-PEN COHESION FRICTION UNIT WT. 1 Soil-1 CONTINUOUS-BLACK 0.00 34.0 120.000 2 Soil—2 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 320.000 *************** * * 40.000 * * 360.000 * * *************** 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 rQ r+ o ! I N N a0 0 0 w co j 0 0 0 0 0 0 0 0 0 0 0 1 . 00 1 . 1 0 1 20 1 . 30 1 . 40 / 1 . 50 1 . 60 1 1 . 70 1 . 80 1 . 90 2 . 00 / PrcJect Har- lkirsorn Datafile static Analysis Bishop STABLE.2002 MZ Associates Ltd APPENDIX D EROSION CONTROL GEOTEXTILE FABRIC GEOTEXTILE FABRIC WRAP AROUND TRENCH 2•x2' WOOD POST BET AND WIRE MESH TO AT LEAST ENTIRE OR EQUIVALENT OR BETTER BOTTOM OF TRENCH @ 6 FT MAX. O.C. 0.5 FT BEFORE PLACING GRAVEL 2'x2'x5' WOOD POST OR I� 6 FT —� 12' DEEP, 8- WIDE TRENCH EQUIVALENT OR BETTER EXISTING Fnl FILLED WITH 3/4' TO 1 1/2' GROUND SURFACE WASHED GRAVEL or VEGETAT�N 11 2 T DIRECTION OF 2•5 FT 12• DEEP, 8' WIDE 1 T WATER FLOW 11 EXISTING TRENCH FILLED WITH 12 GROUND SURFACE 3/4' TO 1 1/2' 2.5 FT 2.5 F7 WASHED GRAVEL OR VEGETATION g-� BOTTOM EXTENTS OF GEOTEXTILE FABRIC SILT FENCE - DETAIL SILT 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 THESE 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. 2. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE 4. HAY OR STRAW IS SUBJECT TO BLOWING. KEEP MOIST OR TIED NSPECTED DAILY AND IMMEDIATELY MAINTAINED, IF NECESSARY. DOWN. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT IN LACE UNTIL THE UPSLOPE AREAS HAVE BEEN PERMANENTLY STABILIZED. PERMANENT EROSION CONTROL NOTES, EMPORARY EROSION CONTROL NOTES- SEEDING FOR RAW SLOPES OR ALL AREAS WHICH HAVE BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAND 1. BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL ISTURBING ACTIVITIES, AND WHERE NO FURTHER WORK IS ANTICIPATED FOR A MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES, ERIOD EXCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE SWALES, LEVEL SPREADERS AND SEDIMENT BASINS. MMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING OR OTHER APPROVED 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE, ROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR. GRASS SEEDING FOLLOWING SURFACE ROUGHENING. PERFORM ALL OPERATIONS ACCROS LONE WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH OR PERPENDICULAR TO THE SLOPE. EPTEMBER. HOWEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST OF 3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE HE OWNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING, NETTING APPLIED AT THE RATE OF 120 POUNDS PER ACRE. R OTHER APPROVED TREATMENT. 4. SEED BEDS PLANTED BETWEEN MAY 1 AND ❑CTOBER 31 WILL REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO RY SEASON (MAY 1 THRU SEPTEMBER 30) -- THE CLEARING OF LAND, INCLUDING THE FOSTER AND PROTECT THE ROOT STRUCTURE. EMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LIMITED TO 5. SEED BEDS PLANTED BETWEEN NOVEMBER 1 AND APRIL 30, NLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE ARMORING OF THE SEED BED WILL BE NECESSARY, (e.g., THERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR OTHERWISE DISTURBED , GEOTEXTILES, JUTE MAT, CLEAR PLASTIC COVERING). Y NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR. UNLESS IMMEDIATE 6. FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS' TABILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL RECOMMENDATIONS. AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY REAS CLEARED OR OTHERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED ADJACENT TO WATER BODIES AND WETLANDS. HROUGH THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, REE DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION LAN OF ACTION, UNLESS ❑THERWISE APPROVED BY THE COUNTY, SEEDING, CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE. ERTILIZING AND MULCHING OF CLEARED OR ❑THERWISE DISTURBED AREAS SHALL BE ERFORMED DURING THE FOLLOWING PERIODS- MARCH 1 TO MAY 15, AND AUGUST 15 TO PROPORTIONS PURITY GERMINATIO CTOBER 1. SEEDING AFTER OCTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION NAME BY WEIGHT(%) (7) (7) F THE PROJECT IS IMMINENT AND THE ENVIROMENTAL CONDITIONS ARE CONDUCIVE ❑ SATISFACTORY GROWTH. IN THE EVENT THAT PERANENT STABILIZATION IS NOT RE➢TOP (AGROSTIS ALBA) 10 92 90 ❑SSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHING, NETTING, ANNUAL RYE (LOLIUM MULTIFLORUM) 40 98 90 LASTIC SHEETING, EROSION BLANKETS, ETC., MUST BE INSTALLED BY NO LATER THAN CHEWING FESUE 40 97 80 EPTEMBER 30. (FESTUCA RUBRA COMMUTATA) (JAMESTOWN, BANNER, SHADOW, KOKET) N THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT WHITE DUTCH CLOVER 10 96 90 CTIVITIES ARE DISCONTINUED FOR AT LEAST 4 CONSECUTIVE DAYS, THE (TRIFOLIUM REPENS) WNER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION ND SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT MULCHING EAST ONCE EVERY WEEK. THE OWNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR HE MAINTENANCE AND REPAIR OF ALL EROSION AN SEDIMENT CONTROL FACILITIES. 1. MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 1000 ET SEASON (OCTOBER 1 THRU APRIL 30) -- ON SITES WHERE UNINTERUPTED POUNDS PER ACRE. ❑NSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE 2. MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES REMOVAL OF EXISTING VEGETATION AND OTHER GROUND COVER, SHALL BE LIMITED GREATER THAN 2-1 (HORIZONTAL-VERTICAL). TO AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HOURS IN 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN HE EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SEDIMENT AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON. ALL TRANSPORT OFF-SITE IS OBSERVED. AREAS REQUIRING MULCH SHALL BE COVERED BY NOVEMBER 1. LL CLEARED OR DISTURBED AREAS SHALL RECEIVE APPROPRIATE PROTECTIVE OVER OR BE ❑THERWISE STABILIZED, SUCH AS MULCHING, NETTING, PLASTIC MEETING, 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. SILT FENCE PROJECT/ OWNER/ LOCATIONt 1. GEOTEXTILE FILTER FABRIC TYPE SHALL BE PER SPECIFIED IN THE 'STORMWATER 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 GE❑TECHNICAL REPORT EACH BARRIER TO AVOID USE OF JOINTS. IF JOINTS ARE NECESSARY, FILTER FABRIC SHALL BE SPLICED R. HANKINSON TOGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT PARCEL 22325-44-92002 BOTH ENDS TO THE POST. MASON COUNTY, WASHINGTON 3. STANDARD FILTER FABRIC SHALL BE FASTENED USING 1' STAPLES OR TIE WIRES (HOG RINGS) @ 4 IN SPACING. 4. POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED IN THE DETAILS ON THIS SHEET, AND ENGINEER, DRIVEN SECURELY INTO THE GROUND. ENVIROTECH ENGINEERING 5. WIRE MESH SHALL BE 2'X2'X14 GAUGE OR EQUIVILENT. THE WIRE MESH MAY BE ELIMINATED IF PO BOX 984 EXTRA-STRENGTH FILTER FABRIC (MONOFILAMENT), AND CLOSER POST SPACING IS USED. BELFAIR, WASHINGTON 98528 6. A TRENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS ON THIS SHEET ALONG THE LINE OF THE 360-275-9374 POSTS AND UPSLOPE FROM THE SILT FENCE. 7, SILT FENCES SHALL BE LOCATED DOWNSL❑PE FROM THE CLEARING LIMITS OF THE PROJECT, ER❑SI❑N CONTROL l