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GeoTechnical Report - GEO General - 7/15/2008
RECEIVED JUL 2 3 Z008 MASON COUNTY GEOTECHNICAL REPORT 6030 GRAPEVIEW LOOP ROAD ALLYN, WASHINGTON PREPARED FOR DAVID G. JORGENSON BY GEOTEC1 LAICAL TESTING LABORATORY, INC. _ OLYMPIA, WASHINGTON DULY 15, 2008 TO BE KEPT IN THE _ PARCEL FILE JI b LD C)� GEOTECHNICAL TESTING LABORATORY 1 CONTACT INFORMATION IPREPARER INFORMATION GTL PROJECT NUMBER: #08-0173 CONTACT: CURTIS D.CUSHMAN ADDRESS: 10011 BLOMBERG STREET SOUTHWEST OLYMPIA,WASHINGTON 98512 TELEPHONE: (360)754-4612 FACSIMILE: (360)754-4848 I EMAIL ADDRESS: GEOTESTLAB@COMCAST.NET CLIENT INFORMATION CLIENT CONTACT: RON PHIPPS CELL PHONE: (360)731-0517 BILLING ADDRESS: P.O.BOX 1238 ALLYN,WASHINGTON 98524 SITE ADDRESS: 6030 GRAPEVIEW LOOP ROAD ALLYN,WASHINGTON 98524 1 PARCEL: #122323100040 GPS LOCATION: N47°21'06.51"W 122°50'04.71" 1 1 #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 2 Phone#: (360)754-4612 Fax#: (360) 754-4848 1 GEOTECHNICAL 7TiNG UnomToRy MIR SCOPE OF UNDERSTANDING DAVID JORGENSON P.O.Box 1238 ALLYN,WASHINGTON 98524 r. RE: GEOTECHNICAL REPORT V 6030 GRAPEVIEw LOOP RD ALLYN,WASHINGTON 98524 O PARCEL#122323100040 N47°21'06.51"W 122°50'04.71 Mr.Jorgensen: As per your request, we have conducted a soils exploration,foundation evaluation, and slope stability analysis for the above-mentioned parcel. The results of this investigation,together with our recommendations, are to be found in the following report. We have provided three copies for your review and distribution. Representative soil sample were submitted for laboratory testing from the project site (H-1). The data have been carefully analyzed to determine soils bearing capacities and footing embedment depths. The results of the exploration and analysis indicate that conventional spread and continuous wall footings appear to be the most suitable type of foundation for the support of the proposed structure. Some variability was encountered in comparing the soil profiles of the site. Net allowable soil pressures, embedment depth, and total expected settlements have been presented for the site later in the report. 1 We are also a full service laboratory that can meet all your building, testing (compaction, asphalt, concrete), and inspection needs. We appreciate this opportunity to be of service to you and we look forward to working with you in the future. If you have any questions concerning the above items, the procedures used, or if we can be of any further assistance please call us at the phone number listed below. �f Was j Respectfully Submitted, GEOTECHNICAL TESTING LABORATORY e, ng ring OeoW&l ` 2439 Curtis D. Cushman, L.G., L.E.G. c+��749 ed Gep�O Senior Engineering Geologist CURTIS DEAN CUSHMAN #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 3 Phone#: (360) 754-4612 Fax#: (360)754-4848 TABLE OF CONTENTS CONTACTINFORMATION.......................................................................................................................................................2 SCOPE OF UNDERSTANDING.................................................................................................................................................3 TABLEOF CONTENTS..............................................................................................................................................................4 INTRODUCTION........................................................................................................................................................................5 SITECONDITIONS....................................................................................................................................................................6 ' Surface Conditions....................................................................................................................................................................6 GEOLOGICALLYHAZARDOUS AREAS.................................................................................................................................8 LandslideHazard Classification................................................................................................................................................8 SeismicHazard Classification...................................................................................................................................................8 ' Erosion Hazard Classification...................................................................................................................................................9................................................... .......................................................Site Geology....................................................... .......... ...9 SiteSoils.................................................................................................................................................................................10 1 Subsurface Explorations............... ...................................................................................................................I l SubsurfaceConditions.............................................................................................................................................................l 1 SoilLogs.................................................................................................................................................................................12 Recommendations for Suitability of Onsite Soils as Fill.........................................................................................................12 ' Theoretical Ultimate Bearing Capacity...................................................................................................................................12 SlopeStability and Analysis....................................................................................................................................................13 Recommendations for Building Setback.................................................................................................................................16 LiquefactionHazard................................................................................................................................................................16 SeismicHazard........................................................................................................................................................................17 Recommendations for Erosion Control...................................................................................................................................17 EARTHWORK........................................................................................................................................................................... 18 Recommendations for Site Preparation...................................................................................................................................18 Recommendations for Structural Fill.......................................................................................................................................18 Recommendations for Cut and Fill Slopes..............................................................................................................................19 ' Recommendations for Foundation Support............................................................ Recommendations for Floor Slab Support..............................................................................................................................19 Recommendations for Retaining Walls...................................................................................................................................20 ' Recommendations for Retaining Wall Alternatives................................................................................................................20 Recommendations for Site Drainage.......................................................................................................................................20 SepticImpact...........................................................................................................................................................................20 CONCLUSIONS AND RECOMMENDATIONS......................................................................................................................21 ' General....................................................................................................................................................................................21 REPORT LIMITATIONS AND GUIDELINES FOR USE........................................................................................................................21 References...............................................................................................................................................................................23 APPENDIX....................................................................................................................................................................................25 LABORATORYRESULTS...............................................................................................................................................................27 SieveAnalysis Hole 1, 10 feet................................................................................................................................................27 SieveAnalysis Hole 1, 15 feet................................................................................................................................................28 ' Sieve Analysis Hole 1,20 feet................................................................................................................................................29 HydrometerHole 1,25 feet....................................................................................................................................................30 ShearResults Hole 1,5 Feet...................................................................................................................................................31 WellLogs........ .......................................................................................................................................................................32 Figure1 Vicinity Map.............................................................................................................................................................33 Figure 2 Site Plan Attached Figure 3 Erosion Control Notes Attached Figure 4 Cross-section Attached #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 4 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1� GEOTEC NICAL TESTING LABORATORY INTRODUCTION ' This report summarizes the results of our geotechnical consulting services for the proposed garage at the subject site. The garage will be constructed on an existing lawn in front of the existing residential building. The 1.67- acre site is approximately 16.5 miles northeast of Shelton, Washington. The site is accessed by Grapeview Loop ' Road off Highway 3 (See aerial Pictures below). The GPS location of the site is shown relative to the surrounding area on the Vicinity Map, Figure 1 (at the end of this report). This report has been commissioned by David Jor ensen. 1 Terraserver USA Aerial Image WA—DOE Coastal Image Our understanding of the project is based on our discussions with the client and our understanding of the requirements of the pertinent ordinances of Mason County. We understand that a garage will be added in the parcel in front of the existing house. In general, grading will consist of the excavation of the foundation and footings for the garage. The approximate layout of the site is shown on the Site Plan, Figure 2. The purpose of our services is to evaluate the surface and subsurface conditions at the site as a basis for providing ' geotechnical recommendations and design criteria for the project and to satisfy the requirements of the Mason County Critical Areas Ordinance. Geotechnical Testing Laboratory, Inc. is therefore providing geologic and hydrogeologic services for the project. Specifically,our scope of services for this project includes the following: 1. A review of the available geologic,hydrogeological and geotechnical data for the site area. 2. A geologic reconnaissance of the site area and surrounding vicinity. ' 3. Investigation and identification of shallow subsurface conditions at the site by characterizing the exposed soil, reviewing published well logs, and on-site drilling. 4. Comparison of site to published geologic maps, previous field investigations, and open file reports. Inspection of aerial photographs to determine the geomorphology of the site. ' 5. Laboratory grain size and shear angle analysis for the soil samples collected from the site. 6. Evaluation of the landslide, erosion, and seismic hazards at the site per the Mason County Critical Areas Ordinance regulations(January 1,2007). ' 7. Building setbacks determined from dynamic slope stability modeling. 8. Geotechnical recommendations for site grading including site preparation, subgrade preparation, fill placement criteria (including hillside grading), temporary and permanent cut and fill slopes, drainage and typical erosion control measures(Figure 3). #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 5 Phone#: (360) 754-4612 Fax#: (360)754-4848 1 GaoTsagNicAL TEsTmG UeoRAToRy The steepest slope measured onsite was approximately 60 percent immediately below the existing residence location, which is an approximately 20 foot above case inlet. The proposed garage site is moderately sloped with slopes ranging from 7 to 18 %. Under the first criterion, Mason County requires that a geotechnical report be prepared in accordance with the Critical Areas Ordinance. 17.01.100E5(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. SITE CONDITIONS SURFACE CONDITIONS The proposed garage site is located in an area of sparse residential development on the hill above the western bank of Case Inlet. The proposed building site is located north of the existing house. The construction area is currently a well maintained lawn. See pictures below: The site was inspected on April 25, 2008 by Vijay Chaudhary under the direction from Curtis D Cushman and the site was drilled on May 19, 2008. The purpose of a site reconnaissance is to physically observe the property and adjacent properties to identify geologic conditions. Photographs and visual observations were documented. Site- specific features were mapped and soil logs were recorded. The surface is covered by grass. Grading has not occurred recently. The sloped areas are well vegetated with species native to northwest Washington. The existing house is located near the bluff. Please see the Site Plan ' (Figure 2) ' #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 6 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1 The north portion of the site will be developed with the proposed garage. The garage site is not vegetated at this time with the exception of lawn grass. The site is essentially flat except at the bluff close to Case Inlet. Site elevations on the entire property range from approximately 0 to 40 feet. The general topography of the site area indicates that drainage flows towards the southeast to the embayment off Case Inlet. The site plan is included as Figure 2. No evidence of active surface erosion was observed. No surface water flow was observed onsite. No ponding of water was observed throughout the site. Slumping and sloughing were not observed throughout the site. No evidence of deep-seated slope instability was observed onsite. No seeps or springs were observed onsite. Onsite trees were observed to be straight and vertical. Review of available geological maps indicated there is no abrupt land mass movement recorded at the site or the vicinity. There are a couple of shallow lakes/wetlands to the northwest of the property. The closest appear to have been largely drained with the remaining water now artificially impounded. There is an apparent wetland extending from here northwest to Catfish Lake. For all of these, drainage would be to the northeast, away fi•om the project site. No hazard is envisioned for the prospect due to these wet areas. The maximum slope is approximately 60 percent along the southeastern slope; the rest of the parcel is of a low slope. The existing septic drainfield has a slope of approximately 7 to 18 percent and is located almost 100 foot away from the bluff. All slope angles were measured using an inclinometer. 17.01.100E5(2) -- A site plan which identifies the important development and geologic features. A site plan is attached as Figure 2 Site Plan at the end of this report. 17.01.100E5(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. A site plan is attached as Figure 2 Site Plan at the end of this report. 17.01.100E5(3) -- Locations and logs of exploratory holes or probes. y A location of the exploratory hole(H -I) has been labeled on Figure 2 Site Plan at the end of this report. 17.01.100E5(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. The area of the proposed development, boundaries of the landslide hazard area, and associated buffers and setbacks are demarcated on Figure 2 Site Plan at the end of this report. Appropriate geology is labeled on Figure 2 Site Plan. 17.01.100E5(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. A cross-section is attached to this report as Figure 4 Cross-section. Minor grading may occur after the publication of this report, is therefore not known at this time, and thus cannot be detailed on the cross-section. #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 7 Phone#: (360) 754-4612 Fax#: (360) 754-4848 r GEO` EC NICAL TUTiNG LABORATORY Ell GEOLOGICALLY HAZARDOUS AREAS LANDSLIDE HAZARD CLASSIFICATION ' I The Mason County Critical Areas Ordinance(17.01.100A1)defines a landslide hazard area as: The following shall be classified as Landslide Hazard Areas: 1 a. Areas with any indications of earth movement such as debris slides, earth flows, slumps and rockfalls (see figure F.100). b.Areas with artificial oversteepened or unengineered slopes, i.e. cuts or fills. ' c. Areas with slopes containing soft or potentially liquefiable soils. d. Areas oversteepened or otherwise unstable as a result of stream incision, stream bank erosion, and undercutting by wave action. ' e. Slopes greater than 15% (8.5 degrees) and having the following: i. Hillsides intersecting geologic contacts with a relatively permeable sediment overlying a relatively impermeable sediment or bedrock(e.g. sand overlying clay);and ' ii. Springs or groundwater seepage. f. Any area with a slope of forty percent or steeper and with a vertical relief of ten or more feet except areas composed of consolidated rock. A slope is delineated by establishing its toe and top and measured by averaging the inclination over at least ten feet of vertical relief. Ik The subject site meets the qualification of a landslide hazard area due to the adjacent slope (to the southeast)that ' is greater than 40 percent and more than 10 feet in vertical height(17.01.1 OOA 1 f). SEISMIC HAZARD CLASSIFICATION ' The Mason County Critical Areas Ordinance(I 7.01.102A)defines a seismic hazard area as: 1.Areas susceptible to ground failure including the following: a. Areas with mapped geologic faults until proven inactive; ' b. Deep road fills and areas of poorly compacted artificial fill; c. Areas with artificially steepened slopes (i.e. old gravel pits); d. Postglacial stream, lake or beach sediments; e. River deltas; f. Areas designated as potential Landslide Hazard Areas; g. Bluff areas; and ' h.Areas underlain by potentially liquefiable soils 2. The following criteria may be used as a guide by the County to indicate areas that have a higher likelihood of meeting the classification criteria above: ' a. Areas identified on the Coastal Zone Atlas of Washington, Volume 9, Mason County as Af. Qal, Qa2, Qvc, Qls, Qos and Qp. b.Areas identified on the Mason County Soil Survey Map as having slopes greater than 15 percent. 1 c. Faults identified on "Map Showing Known or Suspected Faults With Quaternary Displacement in the Pacific Northwest", A.M. Rogers, T.J. Walsh, W.J. Kockelman and G.R. Priest, US Geologic Survey, 1996; or described in "Active Faulting Investigations on the Canyon River Fault, Southern Olympic Range, Washington'; T.J. Walsh and K.G. Neal, U.S. Geologic Survey, 1997. 408-0173 10011 Blomberg Street SW,Olympia, WA 98512 8 Phone#: (360) 754-4612 Fax#: (360)754-4848 d. Areas underlain by potentially liquefiable soils as shown "Liquefaction Susceptibility Map of Mason County, Washington"by Stephen P. Palmer, Sammantha L. Magsino, James L. Poelstra, Eric L. Bilderback, ' Derek S. Folger, and Rebecca A. Niggemann, September 2004 This southern part of the site qualifies as a seismic hazard area because the site is categorized as, "Lf. Areas ' designated as potential Landslide Hazard Areas." EROSION HAZARD CLASSIFICATION ' The purpose of the Erosion Hazard Section (17.01.104A) is to identify areas that present potential dangers to public health and safety, and to prevent the acceleration of natural geological hazards, and to neutralize the risk to ' the property owner from development activities. Areas in Mason County underlain by soils which are subject to severe erosion when disturbed. Such soils include, but are not limited to, those for which potential for erosion ' is identified in the Soil Survey of Mason County, USDA Soil Conservation Service. 1960, or any subsequent revisions or additions to this source. These soils include, but are not limited to, any occurrence of River Wash ("Ra') or Coastal Beaches ("Cg") and the following when they occur on slopes 15%or steeper: ' a.Alderwood gravelly sandy loam ("Ac"and"Ad') b. Cloquallum silt loam ("Cd') c. Harstine gravelly sandy loam ("Hb') d. Kitsap silt loam ("Kc') The soils at the site are mapped as Alderwood gravelly sandy loam (Ab & Ac). This site meets the technical ' criteria of an erosion hazard area SITE GEOLOGY ' The site is generally situated within the g Y _ Puget Sound glacial district. Multiple glacial advances deposited the onsite material. The near surface material was deposited during the most recent Vashon stade (stage) of the Fraser glaciation that occurred between r. about 9,000 and 11,000 years ago. r± r f Weathering and erosion has occurred since. ' The figure (right) is a LiDAR image at a 6- foot resolution. The soils are composed of sandy gravels with varying amounts of sand and minor silt. The individual tests are included in the back ' of the report as well as the drilling log. The description matches that of the Qgt glacial till which is fairly well consolidated. ' The Geologic Map of Washington Northwest Quadrant,Dragovich et al (2002) R has mapped the site geology as glacial till = � 408-0173 10011 Blomberg Street SW,Olympia, WA 98512 9 r Phone#: (360) 754-4612 Fax#: (360) 754-4848 deposits(Qgt)of continental glacial origin. The report reads: ' Till— Unsorted, unstratified, highly compacted mixture of clay, silt, sand, gravel, and boulders deposited by glacial ice; may contain interbedded stratified sand, silt, and gravel. Includes part of the Vashon Drift undivided. ' The Coastal Zone Atlas MA 12 shows the area geology to be the Vashon till(Qvt). See below. Qvt:Non sorted blue gray to gray concrete like mixture of clay, silt and gravel. May contain local layer of sand, gravel and large boulders. L The Geological map of the Vaughn 7.5-Minute Quadrangle, Pierce and Mason Counties by Logan et al (2007)has identified the site geology as a Vashon Till(Qgt)of continental glacial origin. See below: Vashon Till(Qgt): Unstratified to moderately stratified, compact unsorted mixture of clay, silt, sand and gravel, deposited directly by glacial ice, gray to tan; nearly everywhere in sharp contact with underlying units, does not drain well as permeability and porosity are low; sand and finer grains in matrix are very angular, pebble to boulder sized clasts are commonly striated and faceted, having either angular or ' rounded edges,; boulders are generally disseminated and relatively rare„ unit may contain contains interbed of sand and gravel, . The surface of this unit is characterized by streamlined drumlins, striations and flutes that are generally hundreds to thousands offeet long... 1 SITE SOILS 1 The Soil Survey of Mason County, Washington, USDA Soil Conservation Service(1960)has mapped the site soils as an Alderwood gravelly sandy loam, 15 to 30 percent slopes(Ac) in the near coastal area. The report reads: ' This soil varies more in depth, but otherwise it is similar to Alderwood gravelly sandy loams, 5 to 15 percent slopes. It occurs in close association with and adjacent to that soil. It is on moderately steep ridges, along drainage ways, and on elongated irregular slopes. Small areas with slopes of more than 30 percent are mapped with this soil. Surface drainage is more rapid than on the more gentle slopes. Runoff and erosion on the logged and semi cleared areas are controlled by the dense growth of plants. Erosion would damage the soil if it were cleared for crops. The Soil Survey of Mason County, USDA Soil Conservation Service (1960) has mapped the inland site soils as ' Alderwood gravelly sandy loam, 5 to 15 percent slopes(Ab). The survey reads, The Alderwood soils typically formed from mixed gravelly glacial till dominated by acid igneous ' rock. It occupies undulating to rolling moraines. In undisturbed areas a 1-to 2-inch mat of very dark brown, acid organic matter is on the surface. This grade to a thin, dark grayish-brown, highly organic mineral soil. The surface soil consists of a friable, brown, medium acid gravelly ' sandy loam 8 to 13 inches deep. It has a weak granular structure and contains numerous rounded shot. Below the surface soil, to depths ranging from 18 to 24 inches, is a pale-brown gravelly sandy loam that is very friable, is single grained, and contains small to moderate ' amounts of shot. Between this layer and the cemented till is a 3- to 10-inch layer of very pale brown gravelly sandy loam. It contains no shot and is firmer but has the same texture as the layer above. However, it is faintly to distinctly spotted and horizontally streaked with brown and #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 10 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1 GnOTECIR CAL TESTING LABORATORY yellow. The cemented till consists of light-gray, gravelly sandy loam, and it normally occurs at depths ranging from 24 to 32 inches. It is impermeable to roots and very slowly permeable to ' water. The first few inches is usually laminated and streaked with reddish brown and yellow. Below this, to a depth of many feet, the till is uniformly cemented,fairly uniform light gray, and medium to strongly acid. A thin mat of roots often lies over the till. The cemented substratum 1 tends to restrict the rapid downward movement of moisture. Soil removal is only in places needed for construction. All other areas are vegetated with brush, native trees and 1 grasses,etc. SUBSURFACE EXPLORATIONS ' Subsurface conditions at the site were evaluated by observing the exposed building site soil, probing, reviewing available well logs,and drilling. No seeps, seepage,or springs were observed along throughout the site. A 30-foot hole (H-1) was drilled on site and is located in the site plan. Groundwater was encountered at the proposed ' building location and was 22 feet below ground surface. Drinking water will be provided by a well that is existing onsite and has been located on the site plan at the end of this report. ' The soil borings were performed with a conventional tire-mounted Mobil B-40 hollow stem auger drill rig. Representative samples were obtained from the borings at 5-foot soil intervals. The boring log was recorded by Neil Lorenzo on May 19, 2008. The samples obtained by this procedure were classified in the field by the driller, 1 identified according to test boring number and depth, placed in plastic bags to protect against moisture loss, and transported to the laboratory for additional testing. 1 Standard penetration was measured using a two-inch outside diameter, split-spoon sampler driven by a pin-guided, 140-pound weight, and free-falling 30 inches. The blows per six-inch interval were recorded. The first six-inch drive interval is allowed for seating the sampler. The blow counts for two six-inch intervals, when combined, yield the Standard Penetration Resistance (N-Value) of the soils encountered in the sample interval. The SPR is also known as blow counts. The number of blows required to drive the sampler the last 12 inches provides a measure of the relative density of granular soils or the consistency of cohesive soils. When the number of blows exceeds 50 for a six-inch or less advancement of the sampler, refusal is inferred. The results obtained from the Standard Penetration Test, along with other tests and ' geotechnical judgments, were used to develop the recommendations of this report. Samples were collected from five-foot intervals during drilling. They were taken in advance of the bit by the split- spoon sampler. The samples were sealed in Ziploc bags, labeled, and transported to our soils laboratory. Soil gradations were determined by laboratory test method ASTM D-2487 that utilizes the Unified Soil Classification System. The soils laboratory has the following certifications,accreditations,or qualifications: AASHTO American Association of State highway and Transportation Officials AMRL AASHTO Materials Reference Laboratory A2LA American Association for Laboratory Accreditation ' ICC International Code Council SUBSURFACE CONDITIONS The building site is currently covered by grass. In general, dense Alderwood gravelly sandy loam (sandy silty gravel) was observed in the undisturbed areas of the site. Specific soils information is contained in the lab 1 #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 11 Phone#: (360)754-4612 Fax#: (360) 754-4848 1 G " ©TECHNICAL TESTIN(; LAuoRATORY ' analyses and the boring log, in the appendix. Depth to competent soil is approximately 4 to 12 inches throughout the proposed building location. The near surface soils are in dense conditions as refusal was encountered ' throughout drilling. Groundwater was encountered at 22 feet below the surface. Groundwater seepage or springs were not observed along site slopes. However, the well log close to subject site has reported the water table to be 18 foot below ' surface. Refer to the well log at the end of this report. The laboratory results from the drilling indicate we are in a thickness of silty sand with gravel from the surface to the depth drilled. This corresponds closely to the description ' of the till (Qgt). The stiffness of the exposed material indicates it is a glacial till material. SOIL LOGS ' Please see the attached boring log and laboratory analyses later in the appendix. RECOMMENDATIONS FOR SUITABILITY OF ONSITE SOILS AS FILL Drilling samples were tested to determine gradation. Onsite soils may be considered for use as structural fill if industry standards are satisfied. Fill material requirements are found on page 9-29 of the WSDOT Standard Specifications 2008. In general,the native soils(sand, silt,and gravel)encountered on the site must have less than 10 percent fines (material passing the US No. 200 sieve) to be suitable for use as structural fill. Laboratory analysis of the onsite material indicates that the onsite material sampled may not be used as structural fill. (See the laboratory results in the Appendix.) THEORETICAL ULTIMATE BEARING CAPACITY eBased on our laboratory testing conducted on the sample of material collected from subject site, we have calculated the theoretical ultimate bearing capacity. The following Terzaghi formula calculates the ultimate bearing capacity. Using the Figure 6.3, page 173 by Prakash,the bearing capacity factors are determined from the shear angle. Using a factor of safety of three (3), the theoretical maximum bearing capacity is equal to 5195 psf using a shear angle of 34-►. See the following spreadsheet calculation. The IBC (Table 1804.2) lists the allowable foundation pressure as 2,000 psf for silty sand with gravel soil. Terzaghi Equation is given by the following formula: QA = B (cN. +yDrN, + �/2 yBN,) ' c Nc Y Df Nq 0.5 Y B Ny 1 42 125 1 27 0.5 125 2 35 ' Total Bearing Capacity is: 15584 Using a Factor of Safety of 3 5195 c= unit cohesion 1 ' Y= soil density 125 B =footing width 2 D(f)= depth of footing 1 N (c)= bearing capacity factor 42 ' N (q)= bearing capacity factor 27 N (Y )= bearing capacity factor 35 Qd=Total bearing capacity Bearing capacity factors taken from, fig 6.3, Soil Dynamics, Shamsher Prakash, Mc Graw Hill Inc. 1981 #08-0173 10011 Blomberg Street SW,Olympia,WA 98512 1? Phone#: (360) 754-4612 Fax#: (360) 754-4848 i GEOTECHINICAL TESTING Uaommk 1 SLOPE STABILITY AND ANALYSIS 1 In general, the undisturbed native soils of the site consist of O a mixture of variable amounts of sand with some gravel and silt. These soil materials are in a dense and cemented condition , s s. ' except where they have been == disturbed by weathering ' activity. y No evidence of significant k erosion was observed onsite at 1 r the time of our investigation. Instability of this nature is a i typically confined to the upper ' 1 weathered or disturbed zone, which has been disturbed and =_ , has a lower strength. Raveling ; ' and sloughing were not observed on the property. Based ', ` on our experience in this field, ' we conclude that the site is not prone to catastrophic failure in ,' z terms of land mass movement. f,x Our findings were compared '{ u with Coastal Zone Atlas Ma P MA 12 (to the right). The area - e 4: has been described "stable", foundation stability to be "excellent" and seismic stability ' IV. u 1 to be"good". Stale l 34.uW Relative slope stability of the ,% Q Southern Hood Canal Area, uefim ' Washington by Smith and .. Carson, (1977) has mapped the Coastal Zone Atlas MA 12 ' site as a "stable" class 1 area. Class 1 area is described as: Areas believed to be stable. Slopes generally less than 15 percent, but may be greater locally in areas too ' small to be shown at the map scale. Largely comprises rolling uplands underlain by stable material such as young glacial till, mantled in places by this layer of sandy gravel or other permeable material; also includes flood plains, deltas, alluvial fans, and some beach deposits. Class I area immediately adjacent 1 to steep slopes of class 3 areas may be threatened by potential land sliding. Normal,proper engineering practices generally are adequate to insure stability in these areas. 408-0173 10011 Blomberg Street SW,Olympia,WA 98512 13 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY ' It is to be noted that the site and the vicinity has been mapped as Class 1 area and the bold text portion of the description for class 1 area may not be applicable for this site. 1 Weathering, erosion, and the resultant surficial sloughing and landsliding are natural processes that affect slope areas. Significant weathering typically occurs in the upper 2 to 3 feet and is the result of oxidation, root ' penetration, wet/dry cycles and freeze/thaw cycles. Over excavation may be necessary to ensure the removal of deleterious material. These processes can be managed and the risk reduced through proper construction of the residence. Erosion control recommendations in the slope and buffer areas are provided in the "Building Setback" ' and"Erosion Control"sections of this report. Excavation and back filling will occur based on appropriate engineering and earthwork recommendations found in the following"Earthwork" section. Grading in the building portion of the site should be conducted in accordance ' with geotechnical recommendations provided herein. ' Logan and Walsh have mapped minor faults and scarps at approximately one mile to the north-northwest of the site. There is no specific danger associated with these features to the property.No other known faults are mapped in the vicinity of the subject site. ' 17.01.100E5(6) -- A description and results of slope stability analysis performed for both static and seismic loading conditions. Analysis should examine worst-case failures. The analysis should include the Simplified Bishop's Method of Circles. The minimum static safety factor is 1.5; the minimum seismic safety factor is 1.1. And the quasi-static analysis coeffients should be a value of 0.15. Slope stability was modeled using the GeoStudio 2004 program (version 6.20) in both static and dynamic conditions (Ca = 0.15). Factors of safety were determined using Bishop's, Janbu, and the Morgenstern-Price methods. The site was modeled using a layer of sand (see Figure 4 Cross-section). A sample collected upon drilling on site was used to determine shear and cohesion values. The following values were utilized in the slope model: unit weight of 125 pcf, cohesion of 220 psf, and a shear angle (<--) of 34-► (see Appendix for shear test results). The footings will be founded on undisturbed and unyielding native material; hence. the surficial material was not used in the slope model. ' Under static conditions, the slope remained stable to deep-seated and shallow failure. See Figure 4 for the cross- section. The static factor of safety is equal to 2.38 for section "A." Under dynamic loading, the 3328 computations demonstrated that the slope is not susceptible to surficial raveling or large deep-seated failure. The ' following figure illustrates the moment factor of safety for section "A" under the existing conditions. The critical slip surface dynamic factor of safety is equal to 1.69 for section "A." Mason County code requires a static factor of safety of at least 1.50 and a dynamic factor of safety to be at least 1.10 at the proposed building location. ' These are achieved, see below. 1 1 ' 408-0173 10011 Blomberg Street SW,Olympia, WA 98512 14 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1 1GROTECHNICAL TANG LAROMTORY SLOPE MODEL A STATIC MODEL FoS: 2.38 .:�•� y } `'I Alt � -�t ,}it ��y •7� I� �•}' .�• f i 3�. 65 4F- 50 55 rl 50 45 40 0 Description: Silty Sand wl Gravel W-0 20 15 Cohesion: 220 ' 10 Phi: 34 5 0 0 20 40 60 80 100 120 140 180 180 200 220 240 Distance (ft) SLOPE MODEL A DYNAMIC MODEL 1 1 • r 65 eo 55 50 ' 45 C 40 0 35 Silt`Description: Sand wl Gravel .: 30 p Silty > 25 .426 -� 9' 20 Cohesion: 220 W 15 10 Phi: 34 5 ' 0 220 240 0 20 40 60 80 100 120 140 180 1E0 200 Distance (ft) ' #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 15 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TiEsTiNG so ` oR—Y 17.01.100E5(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. The garage will be located on a stable upslope well away from the LHA. The vegetation on the construction site '' is currently a lawn. Native vegetation is abundant on the bluff and should be left intact unless homes or other properties are threatened. The existing drainfield is sited on the map (Figure 2). Available setbacks have been demarcated on the site plan. Maintaining a vegetation buffer between the landslide hazard area and the proposed construction is impractical as the existing house is located right on the bluff itself. We hereby propose the buffer be waived on the rationale that any erosional hazards in this area are addressed by current vegetation of the pre- existing lawn and plantings. The land slide hazard area has been located in the site plan at the end of this report. There are no restrictions envisioned in placing drainage features. See drainage section of the report. 17.01.100E5(11) -- Specifications of final development conditions such as, vegetative management, drainage, erosion control, and buffer widths. RECOMMENDATIONS FOR BUILDING SETBACK ' The building setback may be measured from the bottom of the footing to the face of the steep slope in accordance with the International Building Code 0 805.3.1), see figure to right. Available setback for the proposed construction has been state dint he site plan (Figure 2)at the end ' of this report. As previously discussed, weathering, erosion and scat"ck the resultant surficial sloughing and shallow ' landsliding are natural processes that affect slope areas. Slumping and sloughing were not observed along the slopes. To manage and reduce the potential for these natural processes,we recommend the following: °" No drainage of concentrated surface water or significant sheet flow onto the sloped areas. ' °` No filling within the setback zone. The vegetation in the slope area to remain undisturbed. Native vegetation is encouraged throughout the site where possible. LIQUEFACTION HAZARD The surrounding undisturbed slopes are well vegetated. No springs and seeps along the slope faces were observed. Ground water was encountered at 22 feet. The near-surface soils are generally in a dense condition. Shaking of the already dense soil is not apt to produce a denser configuration and subsequently excess pore water pressures are not likely to be produced. Based on our review of the subsurface conditions, we conclude that the site soils are not susceptible to liquefaction. #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 16 Phone#: (360)754-4612 Fax#: (360)754-4848 1 ' GE®TECHNICAL TEsTiNG nORATORY ' The Liquefaction Susceptibility Map of Mason County, Washington by Palmer, Magsino, Poelstra, Bilderback, Folger, and Niggemann(September 2004)maps the site area as having a very low liquefaction potential. ' The Site Class Map of Mason County, Washington by Palmer, Magsino, Bilderback, Poelstra, Folger, and Niggemann (September 2004) maps the site area as site class B to C. Site class C is a very stiff soil or soft rock. 1 As the site class progresses from A to F,the magnitude of shaking increases in any seismic events. SEISMIC HAZARD tAccording to the Seismic Zone Map of the United States contained in the 2006 International Building Code(IBC), the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g). ' Based on the subsurface conditions observed at the site, we interpret the site conditions to correspond to a seismic Soil Profile Type C, for very dense soil and soft rock, as defined by Table 1613.5.2 (IBC). This is based on drilling results. The shallow soil conditions were assumed to be representative for the site conditions beyond the depths explored. 17.01.100E5(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. RECOMMENDATIONS FOR EROSION CONTROL ' Active surface erosion was not observed on or surrounding the subject site. Evidence of ponding was not observed onsite. It is our opinion that the potential erosion hazard of the site is not a limiting factor for the proposed development. Removal of natural vegetation should be minimized outside of the active construction ' area. Yard landscaping around the garage is permissible, but understory growth on the slopes should be encouraged as much as possible as a deterrent to erosion. ' Temporary and permanent erosion control measures should be implemented and maintained during construction and/or as soon as practical thereafter to limit the additional influx of water to exposed areas and protect potential receiving waters. Erosion control measures should include, but not be limited to, silt fences, berms, and swales with ground cover/protection in exposed areas. Typical erosion control notes and a silt fence detail are included on Figure 2 ' Site Plan. Any re-contouring of the site will create a need for erosion control measures as recommended above. Uses and activities in erosion hazard areas are subjected to erosion hazard area development standards including ' the submittal of a soil and sediment control plan prepared by a professional engineer. 17.01.100E5(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. ' No vegetation is to be removed from the sloped areas. Revegetation of the site with native species is not required. If needed, help from landscape professionals may be sought. ' #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 17 Phone#: (360)754-4612 Fax#: (360) 754-4848 1 GEO` ECHNICAL TESTING LAiOHA'mitt' 17.01.100ES(12) -- Recommendations for the preparation of structural mitigation or details of other proposed mitigation. None envisioned! r EARTHWORK RECOMMENDATIONS FOR SITE PREPARATION ' All areas to be excavated should be cleared of deleterious matter including any existing structures, debris, duff, and vegetation. Based on our observations, we estimate that additional stripping on the order of 4 to 12 inches ' may be necessary to remove the root zone and surficial soils containing organics. Areas with deeper, unsuitable organics may occur in the vicinity of depressions or heavy vegetation. Stripping depths of up to 3 feet may occur in these areas. These materials may be stockpiled and later used for erosion control and landscaping. Surficial material that cannot be used for landscaping or erosion control should be removed from the project site. No foundation elements shall be constructed on"untested"fill material. Where placement of fill material is required, the exposed subgrade areas should be proof-rolled to a firm and unyielding surface prior to placement of any fill. Excavations in any building area should be backfilled with structural fill, and compacted to the density requirements described in the"Structural Fill"section of this report. 1 If structural fill is needed, we recommend that a member of our staff evaluate the exposed subgrade conditions ' after removal of vegetation and topsoil stripping is completed. Any soft, loose or otherwise unsuitable areas delineated during foundation preparation or probing should be compacted, if practical, or over-excavated and replaced with structural fill, based on the recommendations of our report. RECOMMENDATIONS FOR STRUCTURAL FILL ' All fill material should be placed as structural fill. The structural fill should be placed in horizontal lifts of appropriate thickness to allow adequate and uniform compaction of each lift. Fill should be compacted to at least ' 95 percent of MDD(maximum dry density as determined in accordance with ASTM D-1557). The appropriate lift thickness will depend on the fill characteristics and compaction equipment used. We recommend that the appropriate lift thickness be evaluated by our field representative during construction. The suitability of material for use as structural fill will depend on the gradation and moisture content of the soil. ' As the amount of fines (material passing No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult to achieve. During wet weather, we recommend the use of well-graded sand and gravel with less than 9 percent (by weight) passing the No. 200 sieve ' based on that fraction passing the 3/4-inch sieve. If prolonged dry weather prevails during the earthwork and foundation installation phase of construction, a ' somewhat higher(up to 10 percent)fines content will be acceptable. #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 18 Phone#: (360)754-4612 Fax#: (360)754-4848 a 1 GcoTacHNICALTIESTING LABORATIORY 1 Material placed for structural fill should be free of debris, organic matter,trash, and cobbles greater than 6 inches in diameter. The moisture content of the fill material should be adjusted as necessary for proper compaction. RECOMMENDATIONS FOR CUT AND FILL SLOPES * All job site safety issues and precautions are the responsibility of the contractor providing services and/or work. .,, The following cut/fill slope guidelines are provided for planning purposes. ' Temporary cut slopes may be necessary during grading operations. As a general guide,temporary slopes of 1.5 to 1 (horizontal to vertical) or flatter may be used for temporary cuts in the upper 3 to 4 feet of the glacially consolidated soils that are weathered to a loose/medium-dense condition. Temporary slopes of 1 to 1 or flatter ' may be used in the unweathered dense to very dense sands and gravel. These guidelines assume that all surface loads are kept at a minimum distance of at least one half the depth of the cut away from the top of the slope and that significant seepage is not present on the slope face (due to recent rain 1 events). Flatter cut slopes will be necessary where significant raveling or seepage occurs. Surface drainage should be directed away from all slope faces. Straw, hay, or jute matting shall be used to cover ' the exposed soils until permanent vegetation is established. All slopes should be seeded as soon as practical to facilitate the development of a protective vegetative cover or otherwise protected. ' RECOMMENDATIONS FOR FOUNDATION SUPPORT Where foundation elements are located near slopes between 5 and 30 percent, the footings should be located a ' minimum of 2 times the footing width from the slope face (horizontally), and founded in medium dense or denser native soils or properly prepared structural fill. We recommend a minimum width for isolated and continuous wall footings to meet IBC 2006. Footings founded as described above can be designed using an allowable soil bearing capacity of 2,000 psf(pounds per square foot) for combined dead and long-term live loads in areas of medium dense to dense soils. ' The weight of the footing and any overlying backfill may be neglected. The allowable bearing value may be increased by one-third for transient loads such as those induced by seismic events or wind loads. 1 Lateral loads may be resisted by friction on the bases of footings and floor slabs and as passive pressure on the sides of footings. We recommend that an allowable coefficient of friction of 0.25 be used to calculate friction ' between the concrete and the underlying soil. Active pressure may be determined using an allowable equivalent fluid density of 150 pcf(pounds per cubic foot). ' We estimate that settlements of footings designed and constructed as recommended will be less than 1 inch, for the anticipated load conditions, with differential settlements between comparably loaded footings of '/2 inch or less. Most of the settlements should occur essentially as loads are being applied. However, disturbance of the foundation subgrade during construction could result in larger settlements than predicted. RECOMMENDATIONS FOR FLOOR SLAB SUPPORT ' Slabs-on-grade should be supported on medium dense or dense native soils or on structural fill prepared as described in the"Structural Fill"section of this report. We recommend that floor slabs be directly underlain by a ' #08-0173 10011 Blomberg Street SW,Olympia,WA 98512 19 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1 GRO#ECHNICAL TESTING LABORATORY 1 synthetic vapor barrier. Below the synthetic vapor barrier, we recommend a minimum 4-inch thickness of coarse sand and/or gravel containing less than 5 percent fines (by weight). The drainage material should be placed and compacted to an unyielding condition. A synthetic vapor barrier must be used for the control of moisture migration through the slab, particularly where adhesives are used to anchor carpet or tile to the slab. A thin layer of sand may be placed over the vapor barrier and immediately below the slab to protect the liner during steel and/or concrete placement. The lack of a vapor barrier could result in wet spots on the slab, particularly in storage areas. RECOMMENDATIONS FOR RETAINING WALLS ' Retaining walls are not anticipated for this site. RECOMMENDATIONS FOR RETAINING WALL ALTERNATIVES Not applicable. RECOMMENDATIONS FOR SITE DRAINAGE All ground surfaces; pavements and sidewalks should be sloped away from the garage and associated structures. ' Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight-lined into the appropriate drainage facilities. We recommend that conventional roof drains be installed. Footing drains shall be installed for the proposed structure. The roof drain should not be connected to the footing ' drain. For footing drains, the drain invert should be below the bottom of the footing. Typical drainage control measures are included on Figure 3. Onsite irrigation to lawn areas shall be closely monitored. ' We recommend additional testing occur at the proposed infiltration location. Either a double ring infiltrometer or a grain-size calculation will determine the permeability of the onsite material. ' 17.01.100ES(10) An analysis of both on-site and off-site impacts of the proposed development. SEPTIC IMPACT The proposed garage will be located west of the existing septic drain field and to the north of the existing building location. The existing drainfield is located well away from the landslide hazard area and over 17 feet down slope from the proposed garage area. We conclude the slope stability of the site will not be adversely impacted by the existing septic drainfield and the existing septic drainfield will not be adversely impacted by the landslide hazard ' area. We also conclude existing septic drainfield will not adversely impact the proposed structure. No other impacts are envisioned. #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 20 Phone#: (360) 754-4612 Fax#: (360) 7544848 1 1 GEOTECHNICAL TESTING LAHORATORY CONCLUSIONS AND RECOMMENDATIONS ' GENERAL ' Based on the results of our site reconnaissance, subsurface observations, and our experience in the area, it is our opinion that the site is suitable for the proposed project. The proposed garage location is stable relative to deep- seated instability and will not be affected by the proposed structure. The proposed structure will not undermine ' adjacent slopes. Proper drainage control measures will reduce or eliminate the potential for erosion in this area and improve slope stability. ' The hazards of the landslide area can be overcome in such a manner as to prevent harm to property and public health and safety, and the project will cause no significant environmental impact for the life of the project. Onsite soils may not suitable for use as structural fill material; refer to lab analysis attached in the appendix section of this report. Saturated soil conditions may be associated with these soils during or following extended periods of rainfall. However, to reduce grading time and construction costs, we recommend that earthwork be *" undertaken during favorable weather conditions. Conventional construction equipment may be utilized for work at the site. Conventional continuous wall footings ' may be utilized at the site for support of the structure. The choice of footings lies in the purview of the site engineer. We do recommend that roof and footing drains be installed for the structure with the water directed away from the structure. A vapor barrier is recommended for all slab-on-grades. 1 REPORT LIMITATIONS AND GUIDELINES FOR USE ' We have prepared this report for the exclusive use of Mr. David Jorgensen and his authorized agents for the proposed garage in Mason County, Washington. Site inspections, research, and mapping have culminated in this ' report. This report is intended to meet the requirements of the Mason County Critical Areas Ordinance. This report does not specify setbacks for: line-of-sight setbacks, FWHCA setbacks, eagle tree setbacks, wetland setbacks, or property line setbacks. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions,expressed or implied, should be understood. CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS Our geotechnical recommendations are not intended to direct the contractor's procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to onsite personnel and to adjacent properties. READ THESE PROVISIONS CLOSELY Some clients, design professionals,and contractors may not recognize that the geosciences practices(geotechnical engineering or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. Geotechnical Testing Laboratory, Inc. includes these explanatory "limitations" provisions in our reports to help ' #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 21 Phone#: (360)754-4612 Fax#: (360) 754-4848 1 ' reduce such risks. Please confer with Geotechnical Testing Laboratory, Inc. if you are unclear how these "Report Limitations and Guidelines for Use"apply to your project or site. GEOTECHNICAL,GEOLOGIC,AND ENVIRONMENTAL REPORTS SHOULD NOT BE INTERCHANGED ' The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. For that reason, geotechnical engineering or geologic reporting does not usually relate any environmental findings, conclusions or recommendations; e.g., ' about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. 1 1 1 1 ' #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 22 Phone#: (360)754-4612 Fax#: (360)754-4848 1 GEOTECHNICAL TESTING LABORATORY REFERENCES MAPS ' DeLorme 3-D TopoQuads(2002),Source Data USES,Yarmouth,Maine. Logan (2003), Geologic Map of the Shelton 1:100,000 Quadrangle, Washington,(Open file report 2003-15),by published by Washington State Department of Natural Resources. ' Noble and Molenaar(1970), Geologic Map of Southeastern Mason County, Washington, Water Supply Bulletin 29, Plate 1, Published by Washington State Department of Water Resources Palmer, Magsino, Poelstra, Bilderback, Folger, and Niggemann (September 2004), The Liquefaction Susceptibility Map of Mason County, Washington, published by Washington State Department of Natural Resources. ' Palmer, Magsino, Bilderback, Poelstra, Folger, and Niggemann (September 2004), The Site Class Map of Mason County, Washington,published by Washington State Department of Natural Resources. Rogers, A. M., Walsh, T. J., Kockelman, W. J., and Priest, G. R. (1996), Map showing known or suspected faults with quaternary displacement in the Pacific Northwest, published by U.S. Geological Survey OFR 91-441-0, Plate 1, scale 1:2,000,000. ' Smith, Carson(1977), Relative Slope Stability of the Southern Hood Canal Area, Washington, prepared in cooperation with the Washington Department of Natural Resources Division of Geology and Earth Resources: and, Department of the Interior United States Geological Survey. ' Dragovich, Logan, Walsh, and Schasse(2002), Geological Map of Washington—Northwest Quadrant(Geological Map GM- 50),published by Washington State Department of Natural Resources. ' Logan R, Walsh T.J. (2007), Geologic map of the Vaughn 7.5 Minute Quadrangle, Pierce and Mason Counties, Washington (GM-65),published by Department of Natural resources, WA. Washington State Department of Ecology (1979), Coastal Zone Atlas of Washington, Volume 9, published by Washington LW State Department of Ecology. IPUBLICATIONS Ambrose(1981),Simplified Design of Building Foundations,Table 2.5,pages 48-57,published by John Wiley&Sons, Inc. ASTM International(2005),Annual Book of Standards 2005, Section 4, Volume 4.08,published by ASTM International, West Conshohocken,Pennsylvania. International Code Council, Inc.(2004),20031nternational Building Code,published by International Code Council, Inc. International Code Council, Inc.(2006),2006International Building Code,published by International Code Council, Inc. Kollmorgen Instruments Corporation (1994), Munsell Soil Color Charts (1994 Revised Edition), published by Macbeth Division of Kollmorgen Instruments Corporation,New Windsor,New York. Ness,Fowler,Parvin(1960),The Soil Survey of Mason County, Washington, USDA Soil Conservation Sera=ice, in cooperation with the United States Department of Agriculture, and Washington Agricultural Experimental Station, and the Soils Conservation Service. #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 23 Phone#: (360)754-4612 Fax#: (360)754-4848 1 GROTECHNICAL TESTING LABORATORY 1 Parks, Neal, Koloski, Laprade, Molinari, Butler, and Lorentson (November 2006), Guidelines.for Preparing Engineering 1 Geology Reports in Washington, published by Washington State Geologist Licensing Board,Olympia,Washington. Prakash(1981),Soil Dynamics, Figure 6.3,page 173,published by McGraw-Hill,Inc. 1 Washington State Department of Transportation (WSDOT) (2008), Standard Specifications for Road. Bridge, and Municipal Construction 2006 M4140,prepared by WSDOT Engineering Publications,P.O.Box 47408, Olympia, Washington. 1 WEBSITES 1 Mason County Government Information Services (http://www.co.mason.wa.us) Mason County Codes,Ordinances,and Regulations (http://www.co.mason.wa.us/code) Puget Sound Lidar Consortium 1 (http://pugetsoundlidar.ess.washington.edu/lidardata/index.htm]) Slope Stabilization Erosion Control Using Vegetation A Manual of Practice for Coastal Bluff (http://www.ecy.wa.gov/biblio/9330.html) 1 Vegetation Management Guide for Puget Sound Bluff Property Owners (http://www.ecy.wa.gov/biblio/9331.htm I) 1 United States Department of Agriculture Natural Resource Conservation Service (http://soildatamart.nres.usda.gov) 1 Washington Administrative Code (http://apps.leg.wa.gov/wac/) 1 Washington Department of Ecology (http://apps.ecy.wa.gov/welilog) (https:Hfortress.wa.gov/ecy/coastalatias/viewer.htm) 1 1 1 1 1 #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 24 Phone#: (360)754-4612 Fax#: (360) 754-4848 1 1 GE®TF.CHNICAL TEsTiNG LABORATORY 1 ■ APPENDIX 1 1 1 1 1 1 1 1 1 1 1 i 1 1 ' #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 25 Phone#: (360) 754-4612 Fax#: (360)754-4848 1 GEOTECHNICAL TESTING LABORATORY BORING LOG Dvne-. 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Is.1 i atm —IN, 0.150 r.-r% 1?.3% 5 19, 10%Z10 0.act 11 F% In V% 1V C_V91 7*16% 1 s7lt 0.8m I Copyright?Spew,,Engincering&TcchnicM Service-.PS,1386-20" #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 29 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TEsTiNG LABORATORY HYDROMETER HOLE 1,25 FEET xm& in NCINS U.S.Su-MICLU-a ain*Nzwkv-N Hv:&o-w.Am Rz,sa* DO% 4z' Ax -ax K1% ---- -------------------- ----- ... .....------- --------- U4% 9IT0% -----------! ---- ---------—--—---------------------------- 7M ------ ---------- ------ -------------------------- ------------- ------------- ---------- ------------------- 40% ----------- --------------------- --------- ------ ---- --------- -------------------- ------ ------- --------------------- 610% ya -------------f-------- ------ ------ Ly -- ---------------- -------------------- -------------- -- ----------------- ------------------- RIC% ------------ ......... rtom Groin mein Millmetm smaN Cvwzf' Sim, Ccussr Rw rl�'x= U&S-M-7-fi—catil-M 's Gn-,T t6= 1.31 specificatiess %URV6 Nc.Spec$ 54,93% Mmt: AMM-Ton Lig Lt t=C.", ' °5 JI-Irk ED, IUM Flmamnr Nknit-h-s uwv*. PbWtiritV IW>A,-- t.MV 3.t It, YE'S Commit 1.1ses Ar-=L jjw--nr-r'TIri?6 ciwxl�u ore ........... .................. ....... ........................ ............ itz. g j JTT' V�'I, 4.7150 3*&^ aivv 45=1 I an.P.* -41 VALn f 2.25" 313% 0.3m d61. 41-�% r% IMIX% 40 t ISO X.M i9xv M's% 0.150 28,1% am IRA% 4-140 0..If* in a Copyright!Spear,,Engineering&Technic4l Services PS.1336-2004 j 908-0173 10011 Blomberg Street SW,Olympia, WA 98512 30 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1 GEOTECHNICAL TESTING LABORATORY SHEAR RESULTS HOLE 1,5 FEET ' - Peak Shear Stress vs. Normal Stress 1 Shear ' Y 2 TtrR� 1 1 1 1 1 1 ' #08-0173 10011 Blomberg Street SW,Olympia, WA 98512 31 Phone#: (360)754-4612 Fax#: (360) 754-4848 1 WELL LOGS File OnRinal and Flrsl Copy w,th WATER, WELL REPORT Department of Ecology Auphcauon No. Second Copy-Owner's Copy T}iird copy-Drtiler's Copy STATE OF WA UNGTON Permit No i (1) OWNER: Name"_A.1dy Lamar _ _... Address... P.O. . Hox _380I. Allyn, Wa.. 985,24 ' 0 (2) LOCATION OF WELL: Caen,, Mason _ s. .. .. t.sec. 32 T.22 .N. R I wM. CL 4) Be-ing and distance from section or sui.,aw-oo-corner Block 2Q Detroit 2 (a) PROPOSED USE: Domestic R Industrial ❑ Mun,c.,al ❑ (10) WELL LOG: — -_ ' d irrigation ❑ Test Well ❑ dther Q' rarmatton�Detc b�color,character.sae a) mate-1 and stricture,and • shoed thleknese of aqu Jere and tit.kind and watiue of tiff matenat to(deft stratum prnetratad, with at toast one antry fo►eoch change of lortnation. y (4) TYPE OF WORK: wuerts number of well ,� u[,Wore than ones. ...._.. MATERIAL' I irROM TO New well Method: Dug ❑ Bored C _ 'w Deepened ❑ CabTo'-W •Driven❑ T o p g o i Reronditioned❑ Rotary.Q;_ Jetted ❑ ,BrOylll G'O fiq 1011leT at®• �_ 3 r 30 O 30 47_" =O (5) DIMENSIONS: Diameter of well 'Ei:" " 'inches. _ - _ 47 t 50 Drilled6S it Deptn of completed well _�fx5._.;:._tL; S��- ,�r ,i et (�Q• _� -•`_rf,(j 65 cc E (6) CONSTRUCTION DETAILS: L l0 Casing Installed: 5.. Diam from Q n. to . .'.b.�'ri' Threaded❑ " Diam-from. -f(`j -ft Welded C - Diam. from ._, ft. to .:... It- 'I" Perforations: Yes❑ No OType of perforator used.... .. - .'...-..- � ..._�:. � -. - - • 0 SIZE or Perforations .. .---. in by ...... .... in. -•- _. —— '0 ......".. perforations from .... .. ft.to ...perforation from .-•f£.'to .. _ •...-._n perforations from ..... .. IL to.......:_........... 1Y. - =— -- 1 - t4 Screens: Yes❑ No fa Manufacturer&Name - - — •- - V .... -.....".=.....-.:.:.._...._._....:.�....r.... _ t. d Type.............. Dtam. .. Slot stu .. from Diam.. Slot size ....._..from ft.to Gravel packed Yes❑ m.g site atcc gravel:........ .. iGr:.ei placed from - - Surface seal: Ycs�] No❑ To hat Aepth? ' Material used in seat.BBllton.lto . .- ODid any strata contain unusable water? 'tea 0 N o al;. Z Type of water? ..... .._"....... ..... Depth of stra4 Method of sealing strata off. -• H 0 P(7) PUMP: Manufacturer's Noma "•-.._ . .. ._........ _---- `-' - - -- _- - .a Type: _. ...._ ...... ....._... ...'...-.....,H ............. ..... su rface elfvahon _ ($) WATER LEVELS: above mean aea,lif'ret.— ft — __ O static level 19 .n.below top or well. Date6!w.2IIf-_79 VArtesian pressure lba. per square inch Date___ .- - -- — -� ----_---- - _ "- ' (cap.valve..etc) W Artesan water is controlled by i O (9) WELL TESTS Drawdown Is amount:rater level to -i I— - �" lowered below stA11C ievel work atacted..J.0 nAt .I.:S__ iu2.9" CanlpietedJ.Une....211 ... iv. 79 = was a v: mp test maae, 7'es;'] No R if yes,b _y..wbnm? _ Yield. --_rat/mm. with ft. drawdtrwn after hrs. WELL DRILLER'S STATEMENT: 1 ' This weil was drilled under my jurisdiction and this report is i true to the best of my knowledge and belief. CL Recovery data (time taken as zero when pump'411.*d off)�(water level" d measured from well top to water level) Q T+ c Water Level I Tim. Water Leoet Time Water Leoal NAME T..yaa. .61e1Lrm.oillinc�_.Ln..((Type dJ . ...._.. ...............................I....."...."......_.................- ddress.P..Q_...Box n.firm.ore rporsu nl _9Ha o Dnntl .. P o T r _.. i- _ n ` .3Q.,_.A.8 29 .........._.............. *..................... uate or test ..-...- (Signed]hailer test .1 6 ra/min.—th..28 .n.drawdown aner....2._......".has. l ell DrUleri Artesian Bow.__....._ . ..............._..g.p.m. Date.... . . . .. .... ... Temperature of water.._....... Was a chemical analysis made?Yn❑ No El license No. ....Il797 Lute June_ 20 i9. 7.9 .USE ADDITIONAL SHLFra IF NECESSARY, tECr tyo""o •••�,, ' #08-0173 10011 Blomberg Street SW, Olympia, WA 98512 32 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1 FIGURE 1 VICINITY MAP 0 ocks r a _ 1 ■ F u9 r158I1 Ili• j{ ■ q 06.E1 0.`�0 1' 1 y' Y r 1 _ �. 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FLARE END SECTION QUARRY SPALL 1FOOTMIN OR ENERGY DISPERSION DEVICE -0.=> GRASS-LINED SWALE SHOULD BE A MINIMUM ONE FOOT WIDE AT THE BOTTOM AND ONE FOOT DEEP WITH A MAXIMUM SLOPE OF 5 PERCENT. MINIMUM 4 FEET LEVEL SECTION GEOTEXTILE FABRIC Geotechnical Testing Laboratory Geotechnical Services 10011 Blomberg St.SW FIGURE 3 Olympia,WA 98512 QNQC Services phone(380) 4-4 Testing Services Fax:(360)754- DRAINAGE DETAILS 4-4848 Not to scale - 0 LO N z 0 H U W� W v� p fJ U Q N _ ........................ . Gj o�o h� Q Q C O Ln Z Yo UC QU) z �x o �, U)o COO �� -J \O Q O co r CL U0 CD CD LLI Iwo _ 0 < � Q � U) o a LCD n ZLU '-. 0 Oo ca O U CD O M O� CD M LO d' M CD CD ACV CD O z �- o o U C U C� ,6a �Zt 1 t i 1 Mason County Department of Community Develow"�N TY Submittal Checklist For a Geotechnical Report Instructions: This checklist must be submitted with a Geotechnical Report and completed, signed, and stamped by the licensed professional(s)who prepared the Geotechnical Report for review by Mason County pursuant to the Mason County Resource Ordinance. If an item found to be not applicable, the report should explain the basis for the conclusion. Applicant/Owner: David Jorgensen Parcel#: 122323100040 Site Address: 6030 Grapeview Loop Road, Allyn,WA (1) (a) A discussion of general geologic conditions in the vicinity of the proposed development, Located on page(s)�5-&'6 z 7 (b) A discussion of specific soil types Located on page(s) 10 (c) A discussion of ground water conditions Located on page(s) 11 (d) A discussion of the upslope geomorphology Located on page(s) 7 (e) A discussion of the location of upland waterbodies and wetlands Located on page(s) 7 (f) A discussion of history of landslide activity in the activity in the vicinity, as available in the referenced maps and records Located on page(s) 7 & 13 (2) A site plan which identifies the important development and geologic features. Located on Map(s) Figure 2(attached with the report) (3) Locations and logs of exploratory holes or probes. Located on Map(s) Figure 2 (4) The area of the proposed development, the boundaries of the hazard, and associated buffers and setbacks shall be delineated (top, both sides, and toe) on a geologic map of the site. Located on Map(s) Figure 2, Explanation on 16 (5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which incorporates the details of proposed grade changes. Located on Map(s) Figure 4(attached with the report) (6) A description and results of slope stability analyses performed for both static and seismic loading conditions. Analysis should examine worst case failures. The analysis should include the Simplified Bishop's Method of Circles. The minimum static safety factor is 1.5, the minimum seismic safety factor is 1.1. and the quasi-static analysis coeffients should be a value of 0.15. Located on page(s) 14& 15 (7) (a) Appropriate restrictions on placement of drainage features Located on page(s) 16& 20 (b) Appropriate restrictions on placement of septic drain fields Located on page(s) NA as the drain field is existing (c) Appropriate restrictions on placement of compacted fills and footings Located on page(s) 18 & 19 Page 1 of 2 Form Effective June 2008 Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report. (d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes on the property. Located on page(s) 16& Figure 2 (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes on the property. Located on page(s) 16 & Figure 2 (8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation removal. Located on page(s) 17 (9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific mitigating measures to be implemented during construction to protect the slope from erosion, landslides and harmful construction methods. Located on page(s) 17 (10) An analysis of both on-site and off-site impacts of the proposed development. Located on page(s) 20 (11) Specifications of final development conditions such as, vegetative management, drainage, erosion control, and buffer widths. Located on page(s) Covered on points 7 through 11 (12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. Located on page(s) 18 (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. Located on Map(s) Figure 2 I, Curtis D Cushman hereby certify under penalty of perjury that I am a civil engineer licensed in the State of Washington with specialized knowledge of geotechnical/geological engineering or a geologist or engineering geologist licensed in the State of Washington with special knowledge of the local conditions. I also certify that the Geotechnical Report, dated July 15, 2008, and entitled Geotechnical Report, 6030 Grapeview Loop Road, Allyn, Washington meets all the requirements of the Mason County Resource Ordinance, Landslide Hazard Section, is complete and true, that the assessment demonstrates conclusively that the risks posed by the landslide hazard can be mitigated through the included geotechnical design recommendations, and that all hazards are mitigated in such a manner as to prevent harm t Ig.QLoperty and public health and safety. (Signature and Stamp) WaBh!' f 2439 Od G eo�o CURTIS DEAN CUSHMAN Page 2 of 2 Form Effective June 2008 Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report. 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: Permit# Parcel# Date(s)of the Document(s)reviewed: (1) (a)A discu§sion of general geologic conditions in the vicinity of the proposed development, OK? ,L Comment: (b) A discussion of specific soil types OK? ,,, Comment: (c) A discussion of ground water conditions OK?__L, Comment: (d) A discussion of the upslope geomorphology OK? Comment: (e) A discussion of the location of upland waterbodies and wetlands OK? Comment: (f) A discussion of history of landslide activity in the activity in the vicinity, as available in the refer Aced maps and records OK? Comment: (2) A site plan which identifies the important development and geologic features. OK? Comment: (3) Locations and logs of exploratory holes or probes. OK? "' Comment: (4) The area of the proposed development, the boundaries of the hazard, and associated buffers and setbacks shall be delineated (top, both sides, and toe)on a geologic map of the site. OK? =/ Comment: (5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which incorporates the details of proposed grade changes. OK? Comment: (6) A description and results of slope stability analyses performed for both static and seismic loading conditions.Analysis should examine worst case failures. The analysis should include the Simplified Bishop's Method of Circles. The minimum static safety factor is 1.5, the minimum seismic safety factor is 1.1. and the quasi-static analysis coeffients should be a value of 0.15. OK? Comment: (7) (a)Appropriate restrictions on placement of drainage features OK? :/ Comment: (b) Appropriate restrictions on placement of septic drain fields OK? r^'<' Comment: (c) Appropriate restrictions on placement of compacted fills and footings OK?__L/ 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? Comment: (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other$lopes on the property. OK? s " Comment: (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 o�getation removal. OK? Comment: (9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific mitigating measures to be implemented during construction to protect the slope from.erosion, landslides and harmful construction methods. OK? L/ Comment: (10) An analysis of both on-site and off-site impacts of the proposed development. OK? � Comment: (11) Specifications of final development conditions such as, vegetative management, drainage, erosion control, and buffer widths. OK? _ Comment: (12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation. OK? �' 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. OK? i% Comment: Are the Documents signed and stamped? Type and#of License: If not approved, what is the next action/recommendation for further 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