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HomeMy WebLinkAboutGeoTech Report for COM2008-00027 - BLD Engineering / Geo-tech Reports - 5/8/2008 ALKAI CONSULTANTS, LLC. Environmental Engineering • Geotechnical Engineering • Wetland Consulting May 8, 2008 Job# 10149 Mason County Department of Community Development P.O. Box 279 Shelton, WA 98584 Attn: Mr. Wright Geotechnical Report Review Permit#Com 2008-00027 Applicant: South Shore Ent. At your request, we have reviewed a Geotechnical Report for the above referenced permit. The report was prepared by Envirotech Engineering dated November 12, 2007. The report was signed and stamped by Michael Clyde Staten, PE(License#43045). The report contains the information required in the Mason County Code, Landslide Hazardous Areas 8.52.140.E. Further, it is ALKAI's opinion that the report was prepared to at least the typical standard of practice for geotechnical engineering in this area. We therefore recommend that Mason County accept the geotechnical report. Should you have any questions or concerns, or if we may be of additional assistance, please call our office at (360) 613-2407 or contact us by e-mail at Jim@alkai.net. Sincerely, ologist Donald Balmer, L.G. 'C, 1950 Ja es Harding, E.I.T Senior Hydrogeologist Sed ® P0ect Engineer Donald K. Balmer Attachments: Geo Tech Work Order Geotechnical Report: Envirotech Engineering Mason County Requirements Checklist 9465 Provost Road NW, Suite 202 9 Silverdale,Washington 98383 • (360) 613-2407 • Fax: (360) 613-2408 d Project Lp �T� 0e 7 ALKAI CONSULTANTS 5/2/2008 5 tfax--- e:-rT, Mason County Requirements For Geotechnical Reports Mason county code 8.52.140 section 5(E) X❑ 1) A discussion of general geologic conditions,specific soil types,ground water conditions,the upslope geomorphology and location of upland waterbodies and wetlands, and history of landslide activity in the vicinity X❑ 2) A site plan which identifies the important development and geologic features. X❑ 3) Locations and logs of exploratory holes or probes. X❑ 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. XO 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. X❑ 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 coefficients should be a value of 0.15. X❑ 7) Appropriate restrictions on placement of drainage features,septic drain fields and compacted fills and footings, including recommended buffers and setbacks from the landslide hazard areas. X❑ 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. X❑ 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. X❑ 10) An analysis of both on-site and off-site impacts of the proposed development. X❑ 11) Specifications of final development conditions such as, vegetative management, drainage,erosion control, and buffer widths. X❑ 12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. X❑ 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. I � i ALL SE T�3AC'KS .ARE MEASURED FRO^,/1 TIIEFURiHES'f PROJECTION OF THE BUILDING � �•. 120.38 %i 25'REAR SETBACK LINE ;I %' �• I I I I I `• N Io .............................i 3 �I I N V �1 I• 'v- I I li I j bTORMWATER RETENTION be6IGNED FOR EXI$TMG I Warehouse I i WAREHOUSE AND WION OaJARE It 1 I: (EXISTING) I I EXISTING II I I I I EXISTING GRAVEL ROAD I, � I I 1 I I I ; NEW STORMWATER PRIMARY ........................................................................z............+............... .. SEDIMENT POND-SEE CIVIL o i t RETENTION POND 0 1 200.30 EXISTING AND PARIc�M AREAS 25'SIDE SETpAdC LINE _ 1 1 EXISTING PROPERTY LINE SOLID WASTE LOCATION ;•'••••'� , TO DE REMOVED by P MD PARCEL COINATICN Y 'I" 24'-2" I ca O --- — NEW ROAD - 11PROVEMENT6FEW TTED PREVIOUSLY I �+ SEPTIC AND PU°IP TANK AREA I O _ Urtion-Square _. .--___-.-----_ i__ - --- ( O�✓ SEE 6EPtIC DESIGN MY OTHERS 1 I EXISTING RETAIL/OFFICE 1 7 NEW PARKINGAREAS- NEW CPD88WALK I I iv 34 SPACES I I S'-®"¢I i �D 6 ' z II I rU. —L I `----- --- - n ----- ------ ----- ------- I LLLLLLLLLL ------- A DRA"IELD AREA ----- --- - ----- - ----- ------ b 4 -SEE SEPTIC DESIGN 5Y OTHERS NEW ENTRYtEXIT N 88' 320.71 Ex16tING ROAD EDGE t0 6E MODIFIED 90'FRONT 6ETDACK LINE EXISTING EXIT.�.�— _ �•; 6XISTMfi 61,17R1' 5 4 S-BULT CENTERLINE D Iby Road ._ 112'-4" PARCEL NO.: 32232-50-94015 LEGAL DESCRIPTION: Site Plan UNION HOOD CANAL LAND AND IMP CO ELKS: S4-S& LOTS: 1-3, 28-30 E PTNS OF VAC 50GUE t OAKS ST SEE SURVEY 30/5 Scale: I" ■ 50'-0" SITE ADDRESS: NO" 320 E DALBY ROAD UNION,WASHINGTON MASON LPN R p�ED SITE PLAN REQUIRED TO BE ON SITE I PLANNING By CHAN (S SUBJECT TO MZL)--L js _Date Geotechnical Report for South Shore Enterprises, LLC Commercial Building Parcel Number 32232 50 94015 320 Dalby Road Mason County, Washington November 12, 2007 Project#0754 Prepared For: South Shore Enterprises, LLC PO Box 249 Union, Washington 98592 Prepared By: C^ Envirotech Engineering 74 NE Hurd Road Belfair, Washington 98528 � Phone: 360-275-9374 w L Fax: 360-275-4789 EXPIP�s 1 ?�9 TABLE OF CONTENTS 1.0 INTRODUCTION...........................................................................................................................1 1.1 PROJECT DESCRIPTION................................................................................................................. 1 1.2 PURPOSE OF INVESTIGATION.................. ...............................................'..................................... 1 1.3 SCOPE OF WORK.................................•--------------------..................................................................... 1 2.0 SURFACE CONDITIONS..............................................................................................................3 2.1 GENERAL OBSERVATIONS....................................................................'....................................... 2.2 TOPOGRAPHY............................................................................................................................... 2.2.1 Upslope Geomorpholog ....................................................................................................... 2.3 SURFACEDR-UN:AGE..................................................................................................................... 3 2.4 SLOPE.AND EROSION OBSERVATIONS........................•---------......................................................... 11 3.0 SUBSURFACE INVESTIGATION.................................................................................................4 3.1 FIELD METHODS_.---.............................................................•---.......................... 4 3.2 FIELD S LAIPLING AND FIELD TESTING.......................................................................... 4 3.3 GENERA:GEOLOGIC CONDITIONS..... ..........................................................................._...... 4 3.4 SPECIFIC SUBSURFACE CONDITIONS............................................. ........................ 4 3.11 Groundrvater.................................••--------............••••-----------................................................... 5 3.5 SOILSTESTING............................................................................................................................. Is 3.5.1 Visual Classification.................................................................................--........................ 5 4.0 ENGINEERING ANALYSIS,CONCLUSIONS AND RECOMMENDATIONS..........................6 4.1 BUILDING FOUNDATION REcommEND ATIOI S..............................................................................6 4.1.1 Bearing Capacitt............................................................................................................... 0 4.1.3 Concrete Slabs-on-Grade................................................--....................... ............_.............._ 4.2 LATERAL EARTH PRESSURES........................................................ ...................................... 7 4.3 EARTMTORK CONSTRICTION RECOAIAIENDATIONS .................................................................... 7 4.3.1 Exeavation...................................................................................... 7 43.2 Plavement and Compaction c f Native Soils and Engineered Rll.......................................... R 43.3 Retaining Wall Backfill......................................................................................................... 9 4.3.4 Wet Weather Considerations............... ................................................................. ........ 9 4.4 SLOPE STABILITY AND EROSION CONTROL........................................................... 9 4.4, 1 Septic Drain fated Impac-s.....................................................................—-.......................... 10 4.4 2 Building and Rioting Setbacks........................................................................................... 10 1-1.3 Temporary and Permanent Erasion Control............................................................................................ 11 4.4.4 Surface and Subsurface Drainage...................................................................................... 11 4.45 Vegetation Considerations................................................................................--.__......... 12 4.4 6 Off-site impacts................................................................................................................... 12 4.5 SEISAIIC CONSIDERATIONS......................................................................................................... 12 4.6 P:AVEAIENTAN_ALYSIS.............................. ................ ................... •-----..............-............._....... 12 5.0 CLOSURE..................................................................................................................................... 14 Appendix A - Site Plan Appendix B-Geologic Map Appendix C - Soil Information Soil Profile Soil Logs Well Reports 1.0 INTRODUCTION Envirotecb Engineering (Envirotech) has completed a geotechnical investigation for a vacant property identified as parcel number 32232 50 94015 located in Mason County. Washington (Project). The physical address is 320 Dalby Road located near Union. As presented herein_ this report includes infonnation pertaining to the Project in this Introduction Section:. observations of the property and surrounding terrain in the Surface Conditions Section: field methods and soils descriptions in the Subsurface Investigation Section: and.. recommendations for foundation, settlement. carthwork, lateral earth pressures. slope stability and erosion control in the Engineering Analysis and Recommendations Section. An initial geotechnical evaluation of the Project was conducted by Envirotech with the property owner, Rick Buechel of South Shore Enterprises. LLC. on November 1, 2007. Although natural slopes are relatively minor on the property, it ,vas determined that the Project will require a geotechnical report due to the significance of the existing fill within and near the proposed building footprint. During the evaluation and 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. 1.1 Project Description Information pertaining to the Project was provided by-the property-owner. The Project is accessed from an existing paved road (Dalbv Road) linking State Highway 106. See the vicinity map on the following page of this report. At a minimum.the new development is expected to consist of a 1-story commercial building, asphalt paved parking lot_ on-site septic system, and other ancillary- features. The planned building will be 5000 square feet_ used for retail/ office. and founded on concrete footings and slab-on-grade. Approximate building footprint with relation to site features are illustrated in the Site Map in Appendix A. 1.2 Purpose of Investigation The purpose of this geotechnical investigation -,vas to evaluate the Project in order to provide geotechnical recommendations relating to the construction of the planned retail/ office building. The investigation included characterizing the general Project surface and subsurface conditions, and evaluating the suitability of the soils to support the planned site activities. 1.3 Scope of Work In order to fulfill the purpose of investigation, the geotechnical program completed for the proposed improvements of the Project include: • Review project information provided b-y the Project owner and owner's representative_ including field density-reports of the compacted fill: • Conduct a site visit to document the site conditions that may influence the construction and performance of the proposed improvements: • Define the general subsurface conditions of the site by observing excavations of up to 2 feet near the planned building footprint, review geological maps for the general area, research slope stability, and review well logs from an existing well near the Project: • Collect bulk samples at various depths and locations: Em irotccla Lnginccring South Shorc Gcotcchnical Investigation Ph. ,60-27�-9374 pagc 1 Pared 32232 50 94015 Fay: 3fi0-275-47R9 Mason ConTitN. 1ashing1011 Nm cmbcr 12. 2007 • Perform soils testing to determine selected index properties of the soils that include 2 v1sual classifications: • Complete an engineering analysis supported by planned site alterations, and the surface and subsurface conditions that were identified by the field investigation and soil testing.- and, • Establish conclusions based on findings. and make recommendations for foundations. slope stability, erosion control. earthwork construction requirements. and other considerations. J E 2MD ST E 4TH--S ( E KUNN AVE — L E STH ST-(' 0� EPINEST21dR9"4'd ESPRAGUEAVE� E UNgN HEATS OR 1 i w - �.' ( #� ----------- A*0 Project `V „ `I E VUECR� � E HYLAND DR i�� ESTOR� LU E MANZANRA DR �--�--3. ! --- TA COMA POWER ACCESS RD ti0 ej i Camon Lake Vicinity Map.from Mason County Wehsite Endiroteclu Engineerinb South Shore Geotcchnical Imestigation Ph. 360-275-9374 page 2 Parcel ',22i2 jo 9401 Faiv 360-275-4789 Mason C01111IN- WU Ishinguon Nm e-mber 12. 2007 2.0 SURFACE CONDITIONS Information pertaining to the existing surface conditions for the Project was gathered on November 1, 2007 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, soil samples were collected from selected locations, and near-surface soils were visually classified. This Surface Conditions Section provides information on general observations, vegetation, topography, drainage and slope/ erosion conditions for the Project and surrounding areas that may impact the Project. 2.1 General Observations The Project is currently vacant land as previously mentioned. Compacted granular fill exists within most of the southern portion of the property. Commercial buildings exist directly to the east of the property, and Dalby Road borders to the south. A small creek runs across the property from west to east, and is located about 250 feet north of the planned building. Beyond the property lines and adjacent commercial buildings, sparse rural development exists. There is virtually no vegetation within the vicinity of the planned improvements. 2.2 Topography The Project is situated within slightly sloping terrain. The building envelope location is on relatively flat engineered fill over approximately 5% to 8% natural sloping terrain. Natural descending grades of approximately 5% to 8% exist on the property, and extend towards the creek to the north. The fill slope is approximately 2:1, and has a maximum height of 7 feet at the northern edge of the fill pad. The topographic information provided in this section was extrapolated from a public lidar source, and incorporated observations and field measurements. See the Site Map in Appendix A and the Geological Map in Appendix B for an illustration of the general topography, with respect to the planned development. 2.2.1 Upslope Geomorphology Ascending grades are located to the south of the planned development. This slope is approximately 5%to 8%. Steeper ascending grades are located over 300 feet to the south of the planned development. There appears to be a small creek beyond Dalby Road flowing from west to east, over 300 feet from the planned development. 2.3 Surface Drainage Stormwater runoff originating upslope and beyond the southern property line is anticipated to be intercepted by the drainage conveyance adjacent to Dalby Road. Surface drainage within the property appears to sheet flow in a northerly direction to existing infiltration ponds or the creek. Excessive scour, erosion or other indications of past drainage problems were not observed at or near the planned development. 2.4 Slope and Erosion Observations Conditions that could be detrimental to the proposed development with relation to slope movement or erosion were not observed at the time of the site visit. Em irotech Engineering South Shore Geotedmical W\esu_,<tlioii Pli. 360-211S`)37-t page Parcel 32232) 50 94015 Fax: ',60-2'S-178y 19ason County. l�'ashington Noy ember 12. 2007 3.0 SUBSURFACE INVESTIGATION Information on subsurface conditions pertaining to the Project was gathered on November 1, 2007 by Michael Staten, geotechnical engineer with Envirotech. Specific information on field methods,sampling,field testing, subsurface conditions,and results from soil testing are presented in this section of the report. Appendix C has pertinent information on subsurface conditions for the Project, including a soil cross-section, one test pit log representative of the native bearing soils of the building,and one water well report. 3.1 Field Methods Information on subsurface conditions for the Project was accomplished by observing soils within an excavated test hole near the planned building footprint of approximately 2 feet below the existing ground surface. Information on subsurface conditions also included reviewing a water well report originating from a nearby property. 3.2 Field Sampling and Field Testing One bulk sample was collected at the Project site at approximately 2 feet below the existing ground surface near the anticipated building location. The soil sample collected was secured and transported for possible laboratory testing. Relative density of the in-situ soils were accomplished by Envirotech by recording the resistance from hand tools.Field testing results generally indicated medium dense to dense soils in the upper 0.5 feet of the existing native soils, dense from 0.5 feet to 1.5 feet, and very dense soils below 1.5 feet in depth. In addition, the fill material was tested with a nuclear densitometer by Geotechnical Testing Laboratory.These test results are provided in the Field Density Test Report provided in Appendix C.These results indicated dense to very dense compacted fill soils. 3.3 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 Lower Tertiary (Oligocene-Paleocene), ITS. Lower tertiary are generally sedimentary rocks,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 shale, 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. 3.4 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 described utilizing the Unified Soil Classification System Fnv irotcch Engineering South Shore Geotcchnical Imcsll�)aliou Pli. 60-27;)7-4 page 4 Parcel ,2212 �0 9401; Fas: 3b0-27>-�7K9 Mason County� ill(-)toll Nov cmhcr 12 2UU7 (USCS). Using the USCS in conjunction with estimated relative densities and other anticipated engineering properties of the soil, susceptibility for potential landslides, erosion and seismic hazards may be assessed. The Project is composed of compacted fill soils overlying native soils. For engineering purposes, these native soils consist of distinguishable layers,as presented below. Soils beneath the planned building consist of compacted engineered fill ranging from 1 foot to 3.5 feet in depth. These soils were observed to be moist, light brown, dense to very dense poorly- graded gravel with silt and sand (GP-GM). Gravels are primarily coarse and subrounded to subangular. Sand content was primarily coarse, and the fines content exhibited no plasticity. Native soils extending to an unknown depth was observed to be medium dense to very dense, moist, brown silty sand with gravel (SM). Soils at approximately 1.5 feet below natural ground are locally known as `hardpan.' Gravel content was primarily subrounded and coarse. Sand content was primarily well-graded, and the fines content exhibited no plasticity. According to the well report, the hardpan may extend to depths of 25 feet to 75 feet below the ground surface. 3.4.1 Groundwater From the water well report and knowledge of the general area,permanent groundwater is expected to be greater than 50 feet directly below the property at the building pad location. Perched groundwater at shallow depths was not indicated on the well reports. 3.5 Soils Testing The soil samples obtained at the Project site during the field investigation were preserved and transported for possible laboratory testing. Visual classification of soils was performed in the field. The following soil tests were performed in accordance with the American Standards for Testing and Materials(ASTM): 2 Visual Classifications(ASTM D2488) 3.5.1 Visual Classification The general results from the visual classification are presented in the aforementioned Subsurface Conditions Section at depths of up to 2 feet below the natural ground surface. Specifically, native soils within the upper 2 feet consisted of approximately 20% gravel, 60%sand-sized soils, and 20%fines. Fill soils consisted of about 55%gravel, 35%sand and 10% silt. Minor variations observed during the visual classification of particle size content (i.e. gravel, sand, fines), or isolated pockets within the soil stratification were insignificant in relation to the overall engineering properties of the soil. Emirotech Engineering South Shore Gcotechnical investigation Ph. 360-27�937l page> Parcel 32232 50 9401 Fav 360-275-.t789 Mason Count_ Washington Nim cmbcr 12. 2007 4.0 ENGINEERING ANALYSIS,CONCLUSIONS AND RECOMMENDATIONS The following sections present engineering analysis and 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; and, soil conditions that were identified from the geotechmcal investigation that is summarized in the Subsurface Investigation Section. Engineering analysis and recommendations for the Project that is provided herein, includes pertinent information for building foundations, earthwork construction, slope stability/erosion control, and seismic considerations. 4.1 Building Foundation Recommendations Recommendations provided in this section account for the site development of a typical one- story, commercial building. Below the upper 12 inches of Project soils, there are apparently two distinguishable layers of soil that will influence the bearing capacity and settlement of the 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, and deriving probable relative densities, unit weights and angles of internal friction of the in-situ soils based on observed field conditions and soil testing for this Project. The imported fill appears to be sufficiently compacted to withstand the structural loads of both the planned building and parking lot. The competence of the compacted fill is based on the accuracy of the field density tests by Geotechnical Testing Laboratory, and the adherence to the recommendations in this report. 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. The fill soils are not frost susceptible, and the native soils have low to moderate frost susceptible characteristics and should be used only to the extents provided in this report. 4.1.1 Bearing Capacity For the existing site conditions, bearing values should increase with depth. Existing in- situ soils at the Project site 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. Footing width and depth recommendations shall be adhered to,and are based on 2000 pounds per square feet(psf) maximum structural bearing pressure. For a bearing capacity requirement of no more than 2000 psf, a minimum footing width of 16 inches shall be placed at a minimum of 12 inches below the final ground surface on undisturbed engineered fill or native subgrade. These recommendations are made available based on adherence to the remaining recommendations that are provided in this report. Emrirotech Engineering South Shot-e Gcoteclhnical Imestigation Ph. 360-27;-9374 page G Parccl >0 9401 Fax: 360-275-4789 Mason County. Washington Noy Clllber 12. 2001 4.1.2 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. 4.1.3 Concrete Slabs-on-Grade Interior slabs, if utilized, should be supported on a minimum of 6 inches of compacted granular material that is placed over undisturbed native subgrade or engineered fill. Existing compacted fill soils found at the Project site is suitable material for supporting concrete slabs. Although not required for the structural integrity of the concrete slab-on- grade, a vapor barrier is usually used for damp-proofing. If vapor barriers are used, it is suggested to utilize a barrier that is sufficiently thick to resist puncturing during construction, or place a 2 inch layer of sand above the barrier prior to placing the concrete slab. 4.2 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. 4.3 Earthwork Construction Recommendations Founding material for building foundations shall consist of undisturbed previously compacted soils or undisturbed native soils. Additional compacted engineered fill, or selective re-compacted native or fill soils may be used as bearing soils to the extents provided in this Earthwork Construction Recommendations Section. The recommendations include excavations, subgrade preparation,type of fill,and placement of fill for building foundations. 4.3.1 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 incompetent due to inappropriate land disturbing, or excessive water trapped within foundation excavations prior to foundation construction. All soils below HiN irolcch Engineering South Shore Geotechnical Imcstigation Ph. 360-175-1374 page 7 Parcel 32232 iO 9401 Fax: 360-27i-4780 Mason Count. Washington Nm eluber 12. 2007 the bottom of the excavation shall be competent, and relatively undisturbed or properly compacted fill. If these soils are disturbed or deemed incompetent, re-compaction of these soils below the anticipated footing depth is necessary. Excavations shall be completely dewatered, compacted, and suitable before placement of additional native soil, engineered fill or structural concrete. It is recommended that foundation excavations are inspected by a geotechnical engineer or qualified professional in order to assess the bearing material prior to placement of structural footings if the soils are disturbed beneath required foundation depths. 4.3.2 Placement and Compaction of Native Soils and Engineered Fill For additional engineered fill or disturbed native soils that may be utilized as fill material directly beneath foundations, observation and/ or geotechnical testing is recommended prior to foundation construction. Additional fill is anticipated in order to extend the northwest portion of the pad. The following placement and compaction requirements are necessary. For disturbed native soils or new 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 foot for each foot of compacted or re-compacted fill beneath the foundation. See the illustration below. F❑❑TING COMPACTED NATIVE SOILS OR ENGINEERED I FILL 1 I F�--' 'T I ' —I 1 ' UNDISTURBED SUBGRADE Engineered fill for the building pad should be maintained with a minimum of 2:1 (horizontal:vertical) side slopes. A 3-foot depth of the existing pad side slopes should be re-compacted where additional fill is required. Both engineered fill and native soils used as compacted fill should be free of roots and other organics, rocks over 6 inches in size, or any other deleterious matter. Engineered fill should consist of 60%to 100%gravel-sized material(particles between 3/16-inch and 3 inches),and less than 10%fines(particles passing#200 standard sieve)by weight. Compaction shall be achieved in compacted lifts not to exceed 8 inches and 12 inches for native soils and engineered fill, respectively. Each lift should be uniformly compacted to at least 95%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. Em irotech Engineering South Shore Geotechnical Imestigation Ph. ,60-275 9 7-4 Page 8 Parcel iO 9401 Fax: ')60_275-4789 Mason count. Washington Not ember 12. 20U7 4.3.3 Retaining Wall Backfill As previously mentioned, significant retaining structures are not anticipated for this Project. However, if used, native soils may be used as retaining wall backfill for this Project. Backfill may also consist of engineered fill or borrow materials approved by a geotechnical engineer. Placement, compaction and extents of retaining wall backfill should also be specified by a geotechnical engineer or qualified professional. 4.3.4 Wet Weather Considerations Although the subsoil characteristics do not pose a great risk in regards to saturation, additional provisions may be required during prolonged wet weather. Every precaution should be made in order to prevent free moisture from saturating and ponding within excavations. If the bottom of excavations used for footing placement changes from a moist and dense characteristic as presented in this report to loose, saturated conditions, then these soils become unsuitable for foundation bearing material. If this situation occurs, a geotechnical engineer should be notified, or these soils should be completely removed and replaced with suitable compacted material as presented in this section. 4.4 Slope Stability and Erosion Control According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and near terrain labeled `Stable' regarding potential landslide activity. Stable slopes are generally not prone to landslides due to small grades and accommodating geology. This site is not considered inherently hazardous due the existing gentle grades. A Stability Map from the Coastal Zone Atlas for the general area of this Project may be found on the following page of this report. A slope stability analysis was not performed for this project since. This is due to the existing natural slopes with grades less than 10%,and controlled fill slopes. The fill slope is significant on the north end of the pad, about 60 feet north of the planned building, with a vertical relief of about 7 feet. Recommendations are provided in this report concerning features near the fill slope. Emirotech Engineering South Shore Geotechnic it hwcsiigalion Ph. 360-27i-);74 page 9 Parcel �21,2 50 9401; Fax: ,60-27i-4789 Mason Cotint�. Washington Nox cinber 12. 2()()7 Scale 1.24,000 n S k '1i11� 0 $00 low 15M hiclrc% Project 5 r 6- _ r r Map from Washington State Department of Ecology Website 4.4.1 Septic Drainfield Impacts 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, soil properties, relatively minor grades,and the anticipated development,the drainfield is not expected to adversely influence the stability of any slopes within and near the Project, negatively impact the planned commercial building,or negatively influence the fill soils. 4.4.2 Building and Footing Setbacks Although the commercial structure is anticipated to be about 60 feet away from the fill slope,the footing setback is restricted to 10 feet from the top of the fill slope on the north end of the engineered fill pad. However, the setback for structural pavement may be reduced to 5 feet. EnN,irotech Engineering South Shore Gcolechnical lm estigation Ph. 360-275-9374 page 10 Parcel 32232 50 9401 i Pax. 360-27S-4789 Mason Comm. Washington NoN cmbcr 12. 2007 T13P STRUCTURE SLUPE SLOPE FACE _ I I-1-, ,.I 10 FT MIN — FOOTING 4.4.3 Temporary and Permanent Erosion Control Based on the USCS description of the Project soils, the fill soils have a low erodibility factor and the native surface soils are considered moderately erodible. Temporary and/or permanent erosion control measures may be required for site development. Existing erosion control present on-site such as silt fencing and sediment ponds appear to be sufficient for this Project. Additional temporary erosion control measures may need to be employed if excessive erosion occurs or required by the County or other prevailing agencies. See Appendix A for locations of existing erosion control facilities. If necessary, excessive sediments in the retention basin should be removed after construction is complete and the site is permanently stabilized. Permanent erosion control may also be necessary if substantial vegetation has not been established within disturbed areas upon completion of the Project. The fill slopes have already been seeded, and appears sufficient for permanent erosion control. Any runoff allowed to be discharged down any fill slope shall have appropriate outlet protection such as a protected channel. This protection may include pavement or riprap. Areas of permanent erosion control should be monitored until completely established. 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. 4.4.4 Surface and Subsurface Drainage Positive drainage should be provided in the final design for all planned 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 water mitigation will be required. This may include a combination of swales, berms, drain pipes, infiltration facilities, or outlet protection in order to divert water away from the structures. From a geotechnical perspective, both perimeter footing drains and roof drains are optional for the office building. If footings are established at depths greater than 2 feet below final grade,then perimeter footing drains are recommended. If utilized, subsurface water intercepted in the perimeter footing drains, and stormwater collected from roof drains shall be tight-lined to an appropriate infiltration area or outlet protection area located downslope and at least 10 feet from any structure. Em-irotech Engineering South Shore Geotedmical hiN cstigation Ph. 360-27�)�7-4 page 1 l Parccl 322,2 50 9401 Fax: 360-275-4789 Mason CountN. Washington November 12. 2()o7 4.4.5 Vegetation Considerations Vegetation is an excellent measure to minimize surficial slope movements and erosion on slope faces and exposed surfaces. Seeding is necessary on the fill slopes, and should be maintained when necessary.For this Project,the removal of vegetation is not restricted. 4.4.6 Off-site impacts From a geotechnical position,it is Envirotech's opinion that the adjacent properties to the proposed development should not be significantly impacted if all recommendations in this report are followed. This is based on the anticipated and recommended erosion control. Drainage features that are required for this Project that have not been accounted for in this report shall include proper mitigation as to not adversely impact properties beyond the Project. 4.5 Seismic Considerations 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 Hood Canal Fault Zone(Class B), in which the distal end is approximately 3 miles to the northwest of this Project. This information is based on the USGS Quaternary Fault and Fold Database for the United States. The potential for liquefaction and other earthquake induced hazards are believed to be very low for this Project. This is based on subsurface conditions such as soil characteristics and the lack of a permanent shallow water table. Subgrade characteristics that particularly contribute to problems caused by seismic events include submerged, poorly-graded granular soils. 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 sand stratifications are anticipated to be within the upper 50 feet of the subsoil for this Project. 4.6 Pavement Analysis The pavement section design analysis was completed using AASHTO's Guide for Design of Pavement Structures. The AASHTO procedure utilizes the CBR value of the subgrade soil, traffic count reliability, serviceability or ability of the pavement to serve the type of traffic the facility will use, and the material properties of the asphalt concrete (AC) and base course (BC). The traffic data was assumed by Envirotech based on number of buildings and anticipated use. Data on reliability, serviceability, and standard deviation values were assumed based on AASHTO's procedures. The soil modulus was calculated based on correlation of soil properties with R-values. A nomograph presented in the AASHTO Guide, was used to calculate the structural number. Emrirotech Engineering South Shore Gcotechuicat Imestigation Ph. 60-275-91, page 12 Nrccl .;22 2 ;O 9401 Fax: ,60-27i 4?S9 Mason Count. NvJ lshington Nov ember 12. 21007 The thickness of AC and BC were then calculated from the equation relating the structural number and the layer coefficients by assuming a standard AC thickness of 2 inches. Based on the result of the analysis, Envirotech recommends that the following pavement elements be utilized for parking areas: Flexible Pavement Rigid Pavement Asphalt concrete : 2.0 inches 6.0 inches Base coarse : 6.0 inches Concrete in rigid pavements should have a 28-day compressive strength of 3000 psi. Appropriate concrete joints at 20 feet apart with transfer mechanisms should be included. As previously recommended, pavement edges shall be at least 5 feet from the top of fill slopes. Base coarse for parking lot construction should meet the requirements of Class B foundation material from the Washington State Department of Transportation Standard Specifications for Road,Bridge and Municipal Construction. EnOrotech Engineering South Shore Gcotcchnical lmcstigation Ph. 3,60-275 9,74 page l 3 Parcel 32232 50 9401� , Fati: 360-27>-4789 Mason Count_ Washington Noy cnibcr 12. 2007 5.0 CLOSURE Based on the project information 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. Therefore,it is recommended that a qualified engineer observes and documents the construction,or Envirotech is promptly notified if project and subsurface conditions found on-site are not as presented in this report so that we can re-evaluate our recommendations. 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 protect life and property. Semantics such as `suggested' or `optional' refer that the associated design or specification may or may not be performed. 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 ordinances or regulatory codes, or broadening of accepted geotechnical standards may affect the conclusions and recommendations of this report. The services described in this report were prepared under the responsible charge of Michael Staten, a professional engineer with Envirotech. Michael Staten has appropriate education and experience in the field of geotechnical engineering in order to assess landslide hazards, earthquake hazards,and general soil mechanics. Please contact Michael Staten at 360-275-9374 if you have any questions, comments, or require additional information. Sincerely, Enviroteqh Engineering A-J44 Michael Staten,P.E. Geotechnical Engineer Emvirotech Enginecring Sotith Shore Geotedmical Investigation Ph. 60-27 -9 374 page 14 Parcel 22 Q2 50 94015 Fax: 300-27`)-47189 Mason Count. Washington v10ve lber 12. 2007 APPENDIX A SITE PLAN A SCALE, I INCH = 80 FEET ETF-NTION POND 40 rPROPERTY LINE TOP OF EXISTING t 11 FILL SLOPE (FILL DEPTH -9 FT) EXISTING SILT FENCE ol PARKING PROPOSED SEPTIC AREA PROPOSED 5,000 SF BUILDING , ,60 ,. BEGINNING OF FILL (FILL DEPTH = 0 FT) PARKING �x ATIVE GROUND A TP1 DALBY ROAD PROJECT/ OWNER/ LOCATIONS RETAIL/ OFFICE BUILDING GE❑TECHNICAL REPORT SOUTH SHORE ENTERPRISES, LLC 320 DALBY ROAD NOTES LEGEND PARCEL 32232 50 94015 1. TEMPORARY EROSION CONTROL CURRENTLY ON-SITE IS MASON COUNTY WASHINGTW SUFFICIENT. PERMANENT EROSION CONTROL MAY BE REQUIRED ENGINEER- FOR THIS SITE PER THE GEOTECHNICAL REPORT. SILT FENCE ENVIROTECH ENGINEERING 2. CONTOURS ARE NOT PRECISE, AND ONLY DEPICT GENERAL SLOPE DIRECTION 74 ME HURD ROAD TOPOGRAPHIC CONDITIONS. CONTOURS WERE EXTRAPOLATED BELFAIR, WASHINGTON 9MO FROM A PUBLIC LIDAR SOURCE, AND INCORPORATED FIELD �. . EXISTING CONTa1R 360-275-9374 MEASUREMENTS, Tple TEST PIT SITE PLAN APPENDIX B GEOLOGIC MAP SCALE, I INCH = 80 FEET 0 4 ETENTION POND NATIVE SOILS, SILTY SAND WITH GRAVEL (SM) FILL SOILSs "40 POORLY GRADED GRAVEL WITH SILT AND SAND (GP—GM) -PROPERTY LINE , TOE OF EXISTING FILL SLOPE A TOP OF EXISTINGt,l FILL SLOPE (FILL DEPTH —8 FT) EXISTING SILT FENCE ol 5 FT NJEMENT 5E7-SACK PARKING Fxam TOP or Ft t t. st oc PROPOSED SEPTIC AREA PROPOSED 5,)00 SF BUILDING —60 BEGINNING OF FILL (FILL DEPTH = 0 FT) PARKING; µ ATIVE GROUND 44 /I A TP1 A DALBY ROAD PROJECT/ OWNER/ LOCATIOW RETAIL/ ❑FFICE BUILDING GE❑TECHNICAL REPORT SOUTH SHORE ENTERPRISES, LLC 320 DALBY ROAD POTE& LEGEND PARCEL 32M 50 94015 1. NATURAL SLOPES ARE LESS THAN IOX FOR THIS SITE. MASON COUNTY WASHINGTOJ THERE ARE NO MINIMUM BUILDING OR VEGETATION BUFFERS ENGINEER, FOR THIS PROJECT. SEE THE GEOTECHNICAL REPORT SD_T FENCE ENVIROTECH ENGINEERING REGARDING IMPORTED FILL. 74 NE HURD ROAD 2. CONTOURS ARE NOT PRECISE, AND ONLY DEPICT GENERAL SLOPE DIRECTION BELFAIR, WASHINGTON 98528 TOPOGRAPHIC CONDITIONS. CONTOURS WERE EXTRAPOLATED eo EXISTING CONTOUR 360-275-9374 FROM A PUBLIC LIDAR SOURCE, AND INCORPORATED FIELD MEASUREMENTS. TP1 TEST PIT GE❑L❑GIC MAP APPENDIX C SOIL INFORMATION z 4 �F- o q K r� J co W W Z wis m r W J y i p .U-�Q c z a W p[ o LL 1 1 �XN w o �W z w a ZQ~ J 0X 'z- .a Z\L) W It WI �� Q \ 0cno W_> U<w V/JU W I.- Kn 7 W L rwp ._.RZ444 N J o (All w Wn�m I 0 ULO IN Z� 94 0^ .. W Z Z d A N J3 W A~Q O W041Co X GI LO H 1 0 44 Fz rr A J q A W N O 0- 0 w a z Q r 01 J J q -WE w WQ� UJF- A W.-.yq Q�CA 0_ C3 O J W X = 0 �f/)U �'�WFTW WtyQf J X aWf(Y ) W U � �"aC3 z0 p3U Vl0Q d i. WZQQ J l7 W l� Ww� aL34►= �n> i x zQI UK02 Al.7�v W(4wz QXJ`� oe W J 0 z p U J Q w.-. E�-J V1 2 w Lw, Har S y O O ,,H—W z +0CU0 TEST RT LOG TEST PIT NUMBER TP-1 PROJECT: Commercial Bull g Report DATE OF LOG: 1111I2W PROJECT NO: 0754 LOGGED BY: MCS CLIENT; South Shore EnWptises,LLC EXCAVATOR: WA LOCATION: Parcel 32232 5094015 DRILL RIG: None Mason County.Washir gion ELEVATION: WA INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: WA srAN MnuPENEMT=TW DEPTH SAMPLERSUSCS DESCRIPTION LL PI DEPTH N CURVE RM TEST DATA 10 30 50 ' SM Brown,nK**.nudlrm dense b dense SILTY SAND wNh GRAVEL Gmvd is coarse and subrounde&Sand Is 1 pdmo*ws"mds&Low plaod*. Very dense 2 E�ocamdon Imink elsdatapp=ftW*2 led 4 5 6 7 8 9 10 No GrourdwaMr Encowdered ENVIROTECH ENGINEERING iarswbnA.rn�p�rw�.axysosirreapnaano�daarb. Geabdirded eAO arrpwda.aswf�s�aw.ara..am.as.. ""`°t -mer' Copy�.� WATER WELL REPORT 1� 4 CoPy-O.vner's APW(cattoa Nv. --__� hra COPY-Drillers Copy STATE OF WASMNG► M > l) OWNER: tv�t__.13�..u.�...__ .. ...�' ,v�a�caer�.►dd>~�..�r.,x_..S_g�_... .-� ..s�t�....---9 p�9 z :) LOCATION QF co �- �'/�(— +.i . Q//F r fir[- Air f�./ �hhrPi 1it�r L fag and dtstanca hom teettoa s s r 0 d•) PROPOSED USE: Dometaic 91 Industrial p Muntelpat p (10) WELL LOG: lY IrrWatlon Q Test weU Q Oaur Q Formation:DearNbe by color.character,awe of matarlet and atruepae 4hld Show thickne s of aolufers and the kind tad+hetan or and t rust tw inch ? ) TYPE OF WORA: Owner's number of wan 8"eum paaetmted, h at toms one entry for gocl,change to fortum n, tit more tthan anal.-_- New wall A LGthod:Dug ❑ ~Hord Q MAC" sso>tf TO H Deepened O Cabe. jq Ddven E)Rocoodidonad 0 aatary a Jetted 0 C i DBA ENSIGNS: Dlamater of wort__ _.inter Drltled.J4Q_7___& Depth at completed c y L Q— C � CONSTRUCTION DETAIMA — 0 Casi09 fosislJled: -�-Dtam,from-0— tt to !A 7 fL E Threaded O "atom.hvm_ IL to,10 >t Welded J Dim.hom _!L to a Perforatioata: Yas p soA dl TAN of pattorater 8tzz of ptriormIkm in. by 0 L perfandam fttnh_- ft to ft. perforeboaa Lrom ft. to & _ —verfteatioaa boat ft.to Screms: Yes X No Q mmufacturaes No Ad &� Q Type_lz: N/F. %5. Yodel No---- Dlam._V_-slot cu yr_from_....-_it.to Sir ft- slam. slot abs _from fL to fL r Gravel packed: Yes❑ If-jK SL-of gravel:._ Gravel placed from ft.to i S1LlftlCC reel: Yas M No D To" depthl- n Mat-W used to taat�lfACit`ep►_��'� __ Did any strata cantata aauaable waters Yes(3 No a WSW of-rb"—Depth at atrats --- O Method of aesnng-rTata off- ,_� �. zPUMP: Ltaeafaeluaars N..... _�_ d �Ypo: Hp IDATMLEVELS- Land-aarface*low level ._tee O tt blow tap Of wall Data_ -1 G ''- Der aquaee Inch Daft___ O wr'te tao wafer to oonauned by V (Cap,val..:aW_) _ LV Vi'�EL.L TESTS:. D^awdawn is Mwant water level to o.erwd below nestle legal Tf yea•by w work wrtad_?-- L- 0 Pump ttlQ made? Yea R '_.o 0btm7_�/.�/,Jf��. _ kZ' gal✓mta_with :2� ft dm----a after >tira. WELL DRILLER'S STATMIJENT., ��— Y This well was drilled under my Jurisdiction and this fs pw is true to UM beat of mp knowledge and belief. Cc tired troQawNtop to wrier:erel)pump turned off) (water Tavel i Q e Wafar�l.h el Level Time Water I.a.l Nw>►�a'i -�5,t lY..FL 11.-,. 13J-_I.L� lam....... rtnte Water ... } • _ G-� =7_.SC_r.6'.:..... �_— ..---......... _ Arm.ter ( a tPanoncorporauen) or rtRt) .................--•-•---... test ---- m�tn.wtt� t.d.awdown afttr_._.....___.h�y [sijptd]:. f��- • in Date.--__ CCCJJJ •retttre of water----Wes a chemkal anAbYats made?Yes(3 No� --•-.._..___._. 19........ Rev.e.n). (USE ADDITIONAL mere Er may) MASON COUNTY Shelton (360) 427-9670 ' DEPARTMENT OF COMMUNITY DEVELOPMENT Belfair (360) 275-4467 Planning Mason County Bldg.1 411 N.5th Elma (360) 482-5269 P.O.Box 279 Shelton,WA 98584 November 26,2003 Mike Wes W Nevada Corp. TO BE KEPT IN THE- Ocean P.O. Box 9748 PARCEL FILE Scottsdale AZ 85252 Dear Mr. Greenwood: This letter is in response to your inquiry about locating a post office in the Union Rural Activity Center,Mason County,Washington. You are asking, as the construction contractor,whether any specific permitting is needed to site the post office in Union on parcel 32232-50-94015. This parcel is within the Rural Activity Center and is zoned Rural Residential 2.5 (RR2.5). Mason County recognizes the community importance served by a post office and considers thai land use as an essential public facility. In accordance with the Mason County Development Regulations,an essential public facility may be located in any land use zone in the county and must be evaluated through a Special Use Permit. This permit involves an application,public notice, and review by the county's hearing examiner prior to being issued a building permit. Certain conditions of approval may be added to the building permit as a result of this Special Use Permit review. If your firm does receive the competitive bid for this post office building,you will need to apply for this Special Use Permit. You should allow two to three months to complete this permit review. In addition,you should schedule a Pre-Submission Conference at the time of the Special Use Permit review. At this meeting,you will meet with staff members of the planning,building,health, and public works departments to discuss how their respective department development standards apply to the review for your project proposal and any needed special reviews. The Mason County Permit Assistance Center can help you to schedule this meeting in the future. If you have any fin ther questions,please contact me at(360)427-9670 extension 365. Sincerely, Allan Borden Long Range Planner J:\FRONT COUNTER(KMR)\word documents\IRQ RESPONSES\2003 irgs\Ocean West Greenwood letter nov 2003.doc