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HomeMy WebLinkAboutGEO Assessments, Addendums BLD2006-00679 - BLD Engineering / Geo-tech Reports - 6/22/2006 Lb D 006- 00 t MIKE STRAIGHT %ca ve,P.O. Box 149 LILLIWAUP,WA 98555 JU��� Z�Q� RE: DAMAGE ASSESSMENT �fA��Af��'t�L��t SITE: 345 SHAR LANE NORTH 1 fA IL' 6# `1CW0PKS LILLIWAup,WA .98555 w GPS LOCATigW N47029.670' WJ=04.514' PARCEL NUMBER: 309343 DATE: 06/9/2006 Mr. Straight: As requeste we hav up site visit to determine i ditions have changeosince a 2005. Neu To r o eidentical to The recent trenching of ut' ' e acc r a is essential to the p e parcels served bane. Dry raveling of the cut slopes adjacent to Shar Lane is common for well-rounded and unconsolidated glacial drift. Along Shar Lane, vegetation limits are similar to earlier conditions and only minor erosion was observed. After utility construction,no further trenching is anticipated; a roadside ditch will control stormwater. The proposed building location remains undisturbed and ready for construction. No impact has occurred to the southern slope. We determine that conditions remain consistent to the conditions previously observed and reported in our geotechnical report. 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. Respectfully Submitted, GEOTECIINICAL TESTING LABORATORY Harold Parks, L.E.G., L.G. Senior Engineering Geologist Follow u y` 10011 Blomberg Street SW,Olympia, WA 98512 1 Phone#:(360)754-4612 Fax#: (360) 754-4848 �p�,_sTarEa� MASON COUNTY oP A o 9 PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER r o N Shelton, Washington 98584 rZ N Y Y 7Q �O DATE: June 7, 2006 INTER-DEPARTMENTAL COMMUNICATIONS TO: Tammi Clark PARCEL # 32309-34-00030 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-00679 SUBJECT: Geo-Tech Report Review NAME: Straight Mike Tammi, The Geotechnical Report prepared for the proposed new single-family residence and shop located at 345 North Shar Lane near Lilliwaup has been received and briefly reviewed by Public Works. The Geotechnical Report was written May 23, 2005. We need a more recent report preferably done within the last six months. The consultant who did the Geotechnical Report dated May 23, 2006 can send a letter certifying that the report can still be used in lieu of a new Geotechnical Report. A PE stamp would be required on that letter. This can be handled as an addendum to the report if the same report is used. The report appears to satisfactorily address County requirements for Geotechnical Reporting. The report's author indicates that in their opinion that the site is suitable for the proposed project. The author goes on to say that if their analysis and recommendations are followed, they do not anticipate any onsite or offsite impact from the proposed construction. Slope stability was modeled in both static and extreme dynamic conditions. A building setback of 30 feet from the crest of the 30% or more slope to the bottom of the footing should be observed per the report. Adequate erosion and sediment control features need to be implemented during land disturbing activities to protect neighboring properties and State waters from adverse stormwater runoff impacts. The migration or release of silty water or mud from the applicant's property will be considered a violation of County and State water quality protection regulations. Based on the contents of this report, I recommend accepting this report as satisfying the County's requirements for stability investigation and geotechnical reporting after we receive an addendum to this report from the author certifying that the report can still be used in lieu of a new Geotechnical Report. If the addendum has new comments and/or recommendations, those recommendations or comments will need to be reviewed before final acceptance to move forward with this project. Recommendations and Comments contained in the report should be incorporated into the site development plans and made conditions for permit issuance. 1 The Geotechnical Report Review is on hold and no further action will be taken by Public Works until we receive what is requested above. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Sincerely, John Sliva Programs Engineer Geotechnical Report 345 Shar Lane North Lilliwaup, WA Prepared for: Mike Straight by Geotechnical Testing Laboratory Olympia, Washington May 23, 2005 GEOTECHNICAL TESTING LABORATORY MIKE STRAIGHT P.O. Box 149 LILLIWAUP, WA 98555 RE: GEOTECHNICAL REPORT 345 SHAR LANE NORTH LILLIWAUP, WA 98555 PARCEL 323093400030 N47029.670' W 123°04.514' A 4 INTRODUCTION This report summarizes the results of our geotechnical consulting services for the proposed single-family residence and shop to be located near Colony Surf, approximately 3.0 miles northeast of Lilliwaup,Washington. The 2.7-acre site is shoen relative to the surrounding area on the Vicinity Map, Figure 1. Our understanding of the project is based on our discussions with you and our explorations and review of the site. We understand that the parcel is to be developed with a single-family residence. The site will be accessed by a driveway from Shy Creek Road. In general, grading will consist of the excavation of the foundation, footings, and driveway. The site slopes south from a level area toward the Hood Canal. The steepest slope measure' was in excess of 100 percent along roadside cuts. Therefore, Mason County requires that a geotechnica report be prepared in accordance with the Critical Areas Ordinance. 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 is therefore providing geologic and hydrogeologic services for the project. Specifically, our scope of services for this project will include the following: 10011 Blomberg Street SW, Olympia, WA 98512 1 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY 1. Review the available geologic, hydrogeologic, and geotechnical data for the site area. 2. Conduct a geologic reconnaissance of the site area and surrounding vicinity. 3. Investigate shallow subsurface conditions at the site by observing the exposed soil and reviewing published well logs. 4. Evaluate the landslide and erosion hazards at the site per the Mason County Critical Areas Ordinance regulations. 5. Provide 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 erosion control measures. SITE CONDITIONS SURFACE CONDITIONS The proposed building site is located in an area of moderate residential development in the glacial uplands overlooking the Hood Canal. The site has southern exposure. We conducted a reconnaissance of the site area on May 9, 2005. Site elevations range approximately from 400 to 522 feet. A septic system is proposed onsite. The site will be served by a community well. � r ttf�Ftn�J 9Y i �� la rw +J,:' 41 l l The proposed building location had been previously cleared of vegetation. The site slopes are vegetated with a well- mixed variety of vegetation common to the Northwest. The vegetation includes fir, alder, hemlock, and madrone trees as well as Scot's broom, bracken fems, sword ferns, manzanita, rhododendron, salal, huckleberry, foxglove, blackberry, and grasses. The only exposed soil is along the access driveway road cuts. At the time of the site visit, we obse, cviden�e of motive surface erosion at or around the proposed building location. Slope instability was not nimedear the p f ed building location. Active sloughing and raveling was observed along the road cuts. OnsiteallgIM observed vertical. Surface water flow was not observed at the time of our reconnaissance. Groundwater was not encountered or onsite. The groundwater depth was not encountered and is presumed to be deep. The general topography indicates that drainage is toward the south. 10011 Blomberg Street SW, Olympia,WA 98512 2 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SITE GEOLOGY The site is generally situated within the Puget Sound glacial upland. The existing topography, as well as the surficial and shallow subsurface soils in the area, are the result of the most recent Vashon stade(stage)of the Fraser glaciation that occurred between about 10,000 and 12,000 years ago, and weathering and erosion that has occurred since. A description of the surficial soils is included in the "Site Soils" section of this report. In general, e soils are composed of glacial material. SITE SOILS The Soil Survey of Mason Counry, USDA Soil Conservation Service (1960) has mapped the site soils as Hoodsport stony sandy loam, 5 to 15 percent s ,-,The survey reads: This soil differs from Hoodsport gravelly sandy loam, 5 to 15 percent slopes, in having many large, irregular stones and boulders scattered over the surface and in the soil and parent material. This lessens the desirability of this soil for any use. wK" 3C MR; e The Geologic Map of Washington - Northwest Quadrant (2002) has mapped the site geology as glacial till deposits (Qgt) of continental glacial origin. The report reads: Till — Unsorted, unsiratified, highly compacted mixture of clay, silt, _y sand, gravel, and boulders deposited by glacial ice; may contain interbedded stratified sand, silt, and gravel. Includes part of the Vashon Drift undivided. ~' 10011 Blomberg Street SW, Olympia,WA 98512 3 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY WWI ' � ' P «"a ':: 'r :.... t• -k � � .�„"`..u-v+w yJ. mod' �� h � ,� — • -,�•i`, MM a e The Geologic Map of North Central Mason County, Washington (1976) by Carson has mapped the site as Lodgement till (Vlt) L,odgempt till is described as, `compact boulder to clay (generally overlain by 0.5 — 1.5m ablation till." SUBSURFACE EXPLORATIONS Subsurface conditions at the site were evaluated by observing the exposed building site soil and reviewing a 'lable well logs. ,to competent soi, pproximately 6 inches throughout the proposed building location. groundwate resume an-d d-T& -6E a the scope of this project. 40 10011 Blomberg Street SW, Olympia,WA 98512 4 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SUBSURFACE CONDITIONS In general, undisturbed dense Hoodsport gravelly sandy loam was observed throughout the proposed building location. Groundwater seepage was not observed onsite. Based on the site topography and the nature of the near surface soil, s o y perched group wa r coed are not expected during periods of extended wet weather. mail r � n }' M.s der �r 1 ��,.`e�_w •wr'� t?. `y e._ rF a , F SLOPE STABILITY Slopes in exc ss� of 100 percent were observed onsite. Since t ,� slopes of r greater w 40 percent or 10 feet or more of vertical �('� un Oti relief occur on portions of the site, Mason County requires that e M ' a geotechnical report be completed according to the Critical -4— un Areas Ordinance. uB The near-surface soils are in a dense to very dense condition Ayock Pt except at the ground surface. The surficial soils are generally in ? B M a a medium dense condition. In general, the undisturbed native soils of the site consist of a r %! mixture of variable amounts of sand, silt, and gravel. These soil materials are in a dense condition except where they have been disturbed by weathering activity. These soils are generally U18. 3 stable relative to deep-seated failure. Sloughing, undercutting, erg and active erosion were observed along theeroa�cu — 1 Urs ' - urs Weathering, erosion, and the resultant sloughing and shallow ;,� ale 1i 4.000 c landsliding are natural processes that can affect steep slope 5 o w i!oo Werra � ' areas. Instability of this nature is typically confined to the upper J & weathered or disturbed zone, which has been disturbed and has a 5A lower strength. No surface water or active erosion was - observed at the proposed building location. -" 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. Erosion in steep slope areas such as this can be reduced by encouraging vegetation and discouraging runoff from the steep slope. Erosion control recommendations for the sloping areas are provided in the "Erosion Control'section of this report. 10011 Blomberg Street SW, Olympia,WA 98512 5 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY Sri _ i Y � t1 CONCLUSIONS AND RECOMMENDATIONS GENERAL Based on the results of our site reconnaissance, subsurface observations, and our experience in the area.,-a_is our opino_n Lhat the site is suitable for the proposed project. The building location slopes are stable relative to deep- seated instability and will not be affected by the proposed structure if our recommendations are respected. The proposed structure will not undermine adjacent structures. 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 minimized in such a manner as to prevent harm to property and public health and safety, and the project will cause no significant environmental impact. In$eneral, the Hoodsport soils observed at the situ be Suitable for use as structural fill material. Saturated soil conditions mayTe-assoc---iafed—v�i-tfi ht ese soils during or following eR ten pen s o r . 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 spread footings may be utilized at the site for support of the structure. We do recommend that roof and footing drains be installed for the structure with conventional spread footings. A vapor barrier is recommended for all slab-on-grades. Pertinent conclusions and geotechnical recommendations regarding the design and construction of the proposed single-family residence are presented below. LANDSLIDE—EROSION HAZARD AREAS CLASSIFICATION The Mason County Critical Areas Ordinance (17.01.100) defines a landslide hazard area as one containing slopes equal to or greater than 40 percent with more than a 10-foot vertical relief. The southeastern slope is in excess of 40 percent and the vertical relief is in excess of 10 feet. Based on this, this site does meet the technical criteria of a landslide hazard. The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977) describes the southern site area as Class 3. Class 3 is described as: 10011 Blomberg Street SW, Olympia,WA 98512 6 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Areas inferred to be unstable because slopes, generally greater than 15 percent, are underlain by weak, unstable materials in which old or recently active landslides have occurred. Includes areas of sand and gravel on top of impermeable silt and clay, mostly along steep valley sides. The Mason County Critical Areas Ordinance(17.01.104)defines an erosion hazard area as: 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 ("Ae"and "Ad') b. Cloquallum silt loam ("Cd') e. Harstine gravelly sandy loam ("Hb') d. Kitsap silt loam ("Kc') The soils at the site are mapped as Hoodsport gravelly sandy loam (Hg). This site does not meet the technical criteria of an erosion hazard area. SLOPE STABILITY Based on our field observations, explorations and our experience with the soil types encountered on the property, we conclude that although portions of the slopes on the lot exceed 100 percent, the site is generally stable relative to deep-seated failure in their present configuration. The Coastal Zone Atlas, Volume 9, Mason County (MA-3) maps the site as Vashon glacial till (Q,). The a tough, dense material of low permeability. It provides excellent foundation support. The site slope stability is described as `u_nstaba le a the building site, To prevent minor sliding, uncompacted fill material and any underlying vegetation shall be removed in order to construct the foundation. 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. u• A i Mx+ fT ar . r As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural processes that affect slope areas. 10011 Blomberg Street SW, Olympia,WA 98512 7 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 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 destabilizing 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. BUILDING SETBACK A building setback from landslide hazard areas is required unless evaluated and reduced by an engineering geologist or a licensed professional engineer. Based on our geotechnical evaluation of �y the site and our experience in the area, a building setback will be needed for this lot. -1 building sett _of 30-feet from the erect of- ` 30%or — --- -- - tnore) slope3- o tlx bottom of*e footing should Setback otheas+ 6e observed. The building setback may be measuied from the bottom of the footing to the face of the steep slope in accordance with the 2003 International Building Code (IBC). Peak Shear Stress vs. Normal Stress Sandy Loam 3000 -- --- - - - 42° 2500 a2000 m a 0 1500 R L I N i Y 0 1000 500 -► 1/4 ton 1/2 ton 1 ton 0 0 500 1000 15M 2000 25M 3000 Normal Stress(psf) 10011 Blomberg Street SW, Olympia, WA 98512 8 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Slope stability was modeled using the GEO-SLOPE/W program (version 5.20) in both static and extreme dynamic conditions (ca = 0.3). Factors of safety were determined using Straight Site -- Slope A Bishops, Janbu, and the Analysis Method: Morgenstern-Price Morgenstern-Price methods. The Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vertical glacial till was determined to have a unit weight of 131 pcf, cohesion of 200 psf, and a shear angle (�)2f 42' Under static conditions, the slo es Z=c ` le to s allo aiu Under loading, the 3328 computations demonstrat slope is not susceptib e o surficial '. �? . . .:.' rive g or eep-seat as ure.___Yhe followin figu e`-"ill"us tes the g i� f moment factor of safety for slope A" Sao \ �1 2 under the existing conditions. she 520 figure is the solution of greatest S 500 concern and exhibits the need for a o 480 Hooaspac building setback of 30-feet from the > d60 Unk weight 131 P Q7 4 Cohesion:200.( crest(30%or more)of the slope. w 420 Phi:42 40 400 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Distance (ft) As previously discussed, weathering, erosion and the resultant surficial sloughing and shallow landsliding are natural processes that affect slope areas. Surficial raveling and sloughing was observed onsite along_the oversteepened roadside cut. To manage and reduce the potential for these natural processes, we recommend the following: 1. No drainage of concentrated surface water or significant sheet flow onto the sloped areas. 2. No filling within the setback zone unless retained by retaining walls or constructed as an engineered fill. 3. Trees may be removed on sloped(30%or more)areas as long as the stumps remain. T. :7 AWAot •, $. H �1 T A 10011 Blomberg Street SW, Olympia,WA 98512 9 Phone#: (360)754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY SEISMIC—LIQUEFACTION HAZARD According to the Seismic Zone Map of the United States contained in the 2003 International Building Code (IBC), the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g). 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 low liquefaction potential. The Site Class Map of Mason County, Washington by Palmer, Magsmo, Bilderback, Poelstra, Folger, and Niggemann (September 2004) maps the site area as site class C to D. Site class C is a very stiff soil or soft rock and site class D is a stiff soil. 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, as defined by Table 1615.1.1 (IBC). This is based on the range of SPT J (Standard Penetration Test) blow counts and/or probing with a %Z-inch diameter steel probe rod. The shallow soil conditions were assumed to be representative for the site conditions beyond the depths explored. Based on our review of the subsurface conditions, we conclude that the site soils are only mildly susceptible to ligu ion. The near-surface soils are generally in a dense condition and the static water to le is located well below the surface. 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. EROSION CONTROL it is au ^WMIon that the potential erosion hazard of the site is not a limiting factor for the proposed development. Removal,of natural vegetation should be minimized and to the active construction areas. Yard landscaping around a home is permissible,but understory growth on the slopes should be encouraged as much as possible as a D deterrent o n steep slopes ma remain to deter erosion. ern erosion control measures should be installed and maintained during construction or as s limited to, silt fences, berms and swales with ground cover/protection in exposed areas. A typical silt fence detail is included on Figure 2. Any re-contouring of the site will create a need for erosion control measures as listed above. EARTHWORK 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 stripping on the order of 6 to 12 inches will be necessary to remove the root zone and surficial soils containing organics. Areas with deeper, unsuitable organics should be expected in the vicinity of depressions or heavy vegetation. Stripping depths of up to 18 inches may occur in these areas. These materials may be stockpiled and later used for erosion control and landscaping. Materials that cannot be used for landscaping or erosion control should be removed from the project site. 10011 Blomberg Street SW, Olympia,WA 98512 10 Phone#: (360)7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 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. We recommend that trees be removed with the roots, unless located on a slope. Excavations for tree stump removal in any building area should be backfilled with structural fill, compacted to the density requirements described in the "Structural Fill"section of this report. 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. 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 90 percent of MDD (maximum dry density as determined in accordance with ASTM D-1557) to within 2 feet of subgrade and 95 percent MDD in the upper 2 feet. 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 5 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. 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. I 10011 Blomberg Street SW, Olympia,WA 98512 11 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SUITABILITY OF ONSITE SOILS AS FILL Onsite soils may be considered for use as structural fill. In general, the native soils (sand, loam, 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. 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 will likely 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. Flatter cut slopes will be necessary where significant raveling or seepage occurs. Surface drainage shall be directed away from all slope faces. All slopes should be seeded as soon as practical to facilitate the development of a protective vegetative cover or otherwise protected. FOUNDATION SUPPORT ere fundadQuaW&WOMMMM r%TRmxrw-located a ll. We recommend a minimum width for isolated footings and continuous wall footings to meet IBC. 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. Lateral loads may be resisted by friction on the bases of footings r slabs and as passive pressure on the sides of footings. sed to calculate friction between the concrete an e un rlying soil. Passive pressure may be determin g 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%z inch or less. Most of the settlements should occur essentially as loads are being applied. However, disturbance of the foundation sub-grade during construction could result in larger settlements than predicted. 10011 Blomberg Street SW, Olympia,WA 98512 12 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY 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 minimum 6- inch thickness of coarse sand and/or gravel containing less than 3 percent fines (by weight). The drainage material should be placed in one lift and compacted to an unyielding condition. A synthetic vapor barrier may 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. RETAINING WALLS Retaining walls may be utilized on the sloping portion of the site to retain fill material. The lateral pressures acting on the subgrade and retaining walls will depend upon the nature and density of the soil behind the wall. It is also dependent upon the presence or absence of hydrostatic pressure. If the adjacent exterior wall space is backfilled with clean granular, well-drained soil (washed rock), the design active pressure may be taken as 0.40 (coefficient). This design value assumes a level backslope and drained conditions as described below. Retaining walls located on or near the toe of a slope that extends up behind the wall should be designed for a lateral pressure, which includes the surcharge effects of the steep slope in proximity to the wall. Although not expected at this site,the following data is provided for planning purposes. For an irregular or composite slope, the equivalent slope angle may be determined by extending a line upward from the toe of the wall at an angle of 1 to 1 (Horizontal to Vertical) to a point where the line intersects the ground surface. The surcharge effects may be modeled by increasing the equivalent fluid pressure for flat ground by the percentage given in the following table: SLOPE INCLINATION: EQUIVALENT FLUID PRESSURE Slope Angle Percent Increase Equivalent Fluid Pressure Horizontal 0% 35 pcf 3H:1 V 25% 44 pcf 2H:1 V 50% 53 pcf 1H:1V 75% 61 pcf If the walls are greater than 4 feet in height, exclusive of the footing, additional design considerations should be applied. Positive drainage, which controls the development of hydrostatic pressure, can be accomplished by placing a zone of coarse sand and gravel behind the walls. The granular drainage material should contain less than 5 percent fines. The drainage zone should extend horizontally at least 18 inches from the back of the wall. The drainage zone should also extend from the base of the wall to within 1 foot of the top of the wall. The drainage zone should be compacted to approximately 90 percent of the MDD. Over compaction should be avoided as this can lead to excessive lateral pressures. A perforated PVC pipe with a minimum diameter of 4 inches should be placed in the drainage zone along the base of the wall to direct accumulated water to an appropriate discharge location. 10011 Blomberg Street SW, Olympia,WA 98512 13 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY We recommend that a non-woven geotextile filter fabric be placed between the drainage material and the remaining wall backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage zone can, with time, reduce the permeability of the granular material. The filter fabric should be placed in such a way that it fully separates the drainage material and the backfill, and should be extended over the top of the drainage zone. Lateral loads may be resisted by friction on the bases of footings and as passive pressure on the sides of footings and the buried portions of the wall. We recommend that an allowable coefficient of friction of 0.40 be used to calculate friction between the concrete and the underlying soil. RETAINING WALL ALTERNATIVES Typically, block wall systems are more cost effective for long-term walls than the other options. Specific design criteria for these options can be provided at your request by the block manufacturers. SITE DRAINAGE All ground surfaces, pavements, and sidewalks should be sloped away from the residence and associated structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight-lined to an appropriate infiltration area. We recommend that conventional roof drains be installed. Footing drains shall be installed for the single-family residence. 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. We recommend that the collected stormwater runoff be directed, if possible, to the western portion of the site by tight-line. Drainage control measures are included on Figure 3. Onsite irrigation to lawn areas should be closely monitored. We do not expect any adverse affects on the recharge condition of the groundwater system. r� aR 10011 Blomberg Street SW, Olympia, WA 98512 14 Phone#: (360)7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY LIMITATIONS We have prepared this report for Mike Straight and members of his design team,to use in the design of a portion of this project. The data used in preparing this report, and this report, should be provided to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and interpretations are based on data from others and our site reconnaissance, and should not be construed as a warranty of the subsurface conditions. This report is quantified as a micro-study and not a macro-study. Geotechnical Testing Laboratory and its personnel cannot be responsible for unforeseen and widespread geologic events (such as earthquakes, large-scale faulting, and mass wasting)beyond the scope of this project. Variations in subsurface conditions are possible and may occur with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient consultation with our firm during construction should continue, to confirm that the conditions encountered are consistent with those indicated by our observations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork and foundation installation activities comply with our specifications. If our analysis and recommendations are followed, we do not anticipate any onsite or offsite impact from the propos construction. It is our conc usion that potential landslide hazards can be overcome so as not to cause to property, public h6ifth an ­safe_ty­,_o_r__die environment. The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. If there are any changes in the loads, grades, locations, configurations or types of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. ��o{ Was h Respectfully submitted, GEOTECHNICAL TESTING LABORATORY f0 oMOt Harold Parks,L.G., L.E.G. 827 `y Senior Engineering Geologist ante eo�o HAR©LD PARKS 7-3i— os' 10011 Blomberg Street SW, Olympia,WA 98512 15 Phone#: (360) 754-4612 Fax#: (360) 754-4848 • GEOTECHNICAL TESTING LABORATORY Vicinity Map Gal T ramT j"f-- 615 s ' � Paffet .� �.yf• •"� �i'� !�' ' __ .t.i -fit? ,�•; ti -: t�.\_ ,, �s�..J, _ l� I y�f /`mil\yy �yyti .r i �• � 1, �r Fi gure 1 10011 Blomberg Street SW, Olympia,WA 98512 Phone#: (360) 754-4612 Fax#: (360) 754-4848 6/8/2006 Case Activity Listing 7:37:21AM Case#: BLD2006-00679 - Pro Assigned Done Activity Description Date I Date 2 Date 3 Hold Disp To By Updated Updated By BLDB130 Planning Review 4/26/2006 None PEND TSC 5/18/2006 1 SC Pending geo approval. BLDA010 Application Received 4/26/2006 4/26/2006 None DONE KS 4/26/2006 KS BLDA920 Miscellaneous Action 5/1/2006 None DONE TSC TSC 5/1/2006 TSC Called applicant and left message that the site plan(figure 2)in the geo report is partially missing.Will need a complete site plan to review the geo report. BLDB160 Planning Req. for More Info 5/1/2006 None DONE TSC TSC 5/1/2006 TSC Your building permit application for a garage has been received and reviewed by the planning department.The Geotechnical Report submitted is missing a complete site plan(figure 2). I have enclosed a copy of the site plan that was submitted with the report.Please submit the complete site plan(figure 2)from the Geotechnical Report. A site visit was done on 4/28/06.It was unclear as to exactly where the proposed garage will be placed.Please mark the site with the address and stake the area where the garage will be placed. BLDB200 Environmental Health Review 4/26/2006 5/2/2006 None DONE ADR 5/2/2006 ADR BLDA800 Documents Received 5/3/2006 None DONE TAM 5/3/2006 TAM Two sets of plans and one set of engineering calcs received.To building. BLDA800 Documents Received 5/18/2006 None DONE TSC TSC 5/18/2006 TSC Received requested information.Sent Geo Report to Public Works for review. BLDA800 Documents Received 5/22/2006 None DONE CMH 5/22/2006 CMH NEW ENGINEERNIG SUBMITTED SHOWING 40#SNOWLOAD AS PER LARRY KELLY. BLDB110 Building Plan Review 4/26/2006 5/23/2006 None DONE RTB 5/23/2006 RTB ENGINEERING FOR POLE BUILDING IS FOR 25#SNOW LOAD AND AREA STRUCTURE IS BEING BUILT IS 40#.CALLED ALL-PURPOSE STRUCTURES AND TALKED TO JIM AND LET HIM KNOW OF WRONG DESIGN LOAD USE. JIM SAID HE WOULD GET REVISED CALCS TO COUNTY.TOLD HIM TO PUT ATTN TO RTB. review complete sent to case manager 5-23-06 RTB Page 1 of 2 CaseActivity..rpt 6/8/2006 Case Activity Listing 7:37:21AM Case#: BLD2006-00679 P10 Assigned Done Activity Description Date 1 Date 2 Date 3 Hold Disp To By Updated Updated By BLDB225 Public Works Review 5/18/2006 6/7/2006 None DONE JES JES 6/7/2006 if S Report is one year old. Require addendum to Geotechnical Report indicating report can still be used in lieu of new report. Addendum has to be from author with PE stamp. BLDB160 Planning Req. for More Info 6/7/2006 None DONE TSC TSC 6/7/2006 TSC You geotechnical report has been received and reviewed by Public Works.Per the enclosed Inter-Departmental Communications from John Sliva,Programs Engineer,he recommends accepting this report as satisfying the County's requirements for stability investigation and geotechnical reporting AFTER he receives an addendum to this report from the author certifying that the report can still be used in lieu of a new report.Please submit you addendum to the Mason County Permit Assistance Center. Page 2 of 2 CaseActivity-rpt FILTER FABRIC MATERIAL W WIDE ROLLS USE STAPLES OR WIRE RING TO ATTACH Geotec h nic al FABRIC TO WIRE A 2•X7X14 GAUGE VANE FABRIC OR EQUIVALENT 7.p Testing 150, Laboratory / 2..6. e-U N i h' ATE T FILTER STANDARDDR MAERIAL IN MIrTRENCHO OA O BETRORQUALLTERN o ACC S R m STEELCE OSTS CD FILTER FAMC 6• YX2•X14 GAUGE WIRE LZPTI-OCS ED FABRICOR EQUIVALENT 2'.R O /��ED, GROUND SURFACE S'�J(y'y PROVIDE 314"1 VTWA51® LOCATION' /8 '�'/ ' GRAVEL BOTH SI IN TOF RENCH 2 AND EL BDTHSIDESTRENCHR FENCE FABRI C ONHE SURFACE 6•MN -_- C T' ALT:WOOD POSTS Geotechnical Services ACT:STEEL FENCEPoSTS FILTER FABRIC FB1LfNOTB6: QA/�r JerVICW es 1.FILTER FABRIC SHALL BE PURCHASED IN ACONINUOUS ROLL CUTTO THE LENGTH OF THE BARRIER TO AVOIDUSE OF JOINTS.WHBRJOINTS Testing Services ' ARE NECESSARY.FILTER ttCTH SHALL BE SPIJC_TOGERH2ON.Y AT A SUPPORT POST WITH A MINIMUM BINCH OVERLAP APDSECURELY FASTENED AT BOTH ENDS TOTFE POST. --- _-_---_ --- - 2.POSTS SMALL BE SPACED TOTHE F S OF6FEET MPRT MD DRIVEN D 6 SECURELY INTO THE GROUND(MNMUM OF 301NCIE5). ' 3.ATRENCHSHALLBEEXCAVATEDAPPROXIMATELY$INCHESWDEAW12 10011 Blomberg St.SW POTENTIAL ; ( INCHESDEEP ALONG THE LINE OFPOSTSAPDlA3OPEFROMTEBARRIER OlyrMia WA 98512 INFILTRATION - '" B IL IN 7 �I- - g ' 4.WHEN STANDARD STRENGTH FILTER FABRICISUSED,AYARE MESH Phone:(360)754-4612 _-t�A�rol`I i OF TH POSTS USING SHALL SECURELY LEAST 3OPESCE L _ - - LOHEIE"RESORHOGW.GS.THE ESTPAESAT ENDININCHOT Fax:(360)754-4848 ` C TRENCHIE MINIMUM HOG RINGS.THESHALLN TEKTEN0D ORETE 6� 1 TRENCIiAMINIMUM OF 4INCHES PAID SHALL NOT FXfB�D MORETHAN 36 INCHES ABOVE THE ORIGINAL GROLI D SURFACE_ _� --- _. _- M •� 5,THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WRID ` - i1. ,' TTO THE FENCE NT THETRENCH,HEFAHRICSH�TEMENDf�36 Date: ed by:: LL _ yC N INCHES ABOVE THE ORIGINAL GROUND S.RRFACE.FLIER FABRIC 94AL Designed by: LL -----CID -_- `------ - -- - N NOT BESTAPI_TOTHEDOs1,NGTREES Drawn by: LL 00 j t� 6 WHEN Exrna a sTRGHHLTERFABRICADCLOSERP0Sf5PAONGIs Checked by: LL ------------------- C�!� r$R ABED THE MESH SUPPORT FENCE MAR BE ELIMINATED.IN SKIT DWg#:05-13-05-042 ] � A CASE.HE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THE - ______---'`-- POSTS WITH ALL OTHER PROVISIONS OR ABOVE NOTES APPLYING. ;�1.`I 7.F1'LLTERFAABR PER ES SHALLY ST PBILIIIEID. ���THELPSLOPE ___ ____________________________ ----- 6.FILTERRAINFALL LLFABRICAND AT LEAS DAILY RE INSPECTED NGEDIATAYLL A EACH --_ RAINFALL KIND AT LEAST DAILY WRING PROLONGED RAINFALL NJY ____________________________________ IMMEDIATELY -_ ______ _ OENERIIL EROSION CONTROLIDTC•6: _____9.'____ 1. EROSION CONTROL MEASURES SHALL REIN RACE PRIOR TO THE BEGINNING OF CONSTRUCTION.THE PRO•ECT BJGIN�RADTE LOUMY NS SHALL 490 EROSION CONTROLDMSUPES PRIOR TOEE NNNG CONS RUCBON. �. _ --__ 2.EROSION CONTROL CONTRACTOR NOT ESPONEE FOR THE ______________________ ON THIS PLAN.AND MAINTRACTORI OF ALLE EROSION FORTE \\ - INSTALLATION AND EXISTING NANCEOF EDEROSIONCONTROLMEASURES. NO SILTATION OF EJOSTING OR PROPOSED DRAINAGE PROJECT NAME: ------------ - SHALL BE ALLOWED.CARE SHALL BE TAKEN TO PREVENT MIGRATION _ --------------- ---------------- ------------ ---- NORTH OF SILTS TO OFF SITE PROPERTIES MIKE STRAIGHT -----------------------------'_ 3.THE CONTRACTOR SHALL MAKE DAILY SURVBLLMICEOFNIEROSION 345 SHAR LANE NORTH \\- __-_ ------------------------------------ ------------ -- SCALE I"=50 CONTROL MEASURES AND MAKE ANY NECESSARY REPAIRS OR ALgTONS 480 _____ ------------ - C.I.=z TO THE EROSION CONTROL CONTROL MEAS ESASTHEC DR7ALTOR SHCESSAR CE ____ ADDITIONAL EROSION CONTROL MEASURES AS pETHSANEDNECESSPRY ---------------- --------------- -------------_ -_-_-_ DATUM ASSUMED BY THE COUNTY INSPECTOR ANDIOR THE PROJECT ENGINEER.FAILURE LILLIWAUP,WASHI '- ----------'-- - .err-rr ----------- THIS IS NOT TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL PARCEL 323093400030 -- --------- - - - --- AGAINST THE C MAY RESULT IN OIMLPBR CT OWNER ____________ __- AGAINST THE CONTRACTOR NCYOfR PROJECT __ __ R,WRING DI ------------- THE WET TO MARCH)ALL SRA28EDSOILS ________ / - _- �r��r�rr 10 20 30 40 50 I i � -^----- ---- SHALL BE STABILIZED WITHIN 46 HOURS AFTER STOP CF ________ ____ CONTROL MEASURES SHALL INCLUDE,Bllf TEE UMT®T0. G�h11 . _____ _ _ _ COVERING STICSNTHE EFFECT_AREA INCLLOING SPOIL PLES WITH / ;- i�_____ __} ______ ___ ORAWOOD IL E SEE.N.O'HEDISRR�AREASSiP11TA1@CH, I I I l / / 't / %__ __ PLACE AS WEATHER PERMITS. II'^ R /I gCSI Rb lI 1 S.ALL SEEDED OR SODDED AREAS SHALL BE CHECKED REGENCY W 1 TO MAKE SURE VEGETATIVE COVERAGE ISOOALEIE.AREAS SHALL BE / 1 I �.} REPAIRED.RESEEDED.AND FERTILIZED ASREOLARED. VM ____ - - 8.TRACKING OF SOIL OFFSTE WILL NOT BE ALLOWED.IF NR1'SOLLIS __________________ 1 1 TRACKED ONTO ACOUNTY 5TREET,IT SFWLBE REMOVID17/TNEEND ----- ------ ------- _ I /1 �//�� OF THAT WORKING DAY.ANY FURTHEPTRACION60FMAWILLIHEN __ I_ _i \1/ ___ BE PREVENTED BY SWEEPING OR WASHING OF THE VB#CESTIRES __ -__ _ BEFORE DRIVING ONA WIMTY STREET. 7 NO MORE THAN 600 LF OF TRENCH ON ADNMSLOPEOF MORE THAN 5 PERCENT SHALL BE OFE SDATOFETME 8.EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SCE OF TRENCHES S TRENCH NOT ADVERSELYAAFFECTTERING FOWINCES NGGALL BE STREAMS.D�RNNGEINSY�OR WILL OPFSITE PROPERTIES. SCAR:1 50 fee 10.ALL STORM SEWER INLETS RECEIVING RUNOFF FROM7HE P7O•ECT DURING CONSTRUCTION SHALL BE PROTECTED SOTHAT SEDIMENT-LPLeR WATER '�AA�•� N WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM, N 11.ALL OFF.LLBESITEPROTECEBASINSDFROMIMMET%A7aYIAlACBdTTOTHESITE FIGURE 2 �A•� SHALL BE PROTECT_FRIX4 SILTATION. O W 12 ALL DISTURBED AREAS SHALL BE SEEDED OR SOCC_U'ON NAPltT1ON OF WORK.THE CONTRACTOR SHALLERESPONSBLETO @RSFETHAi N r COMPLETE COVERAGE OF THEp STUR�D ARFASISP ONDW LTHAT GROWTH OF THE VEGETATION 15 ESTABUSHED 13 CATCH BASINS SHALL TRAP IMENT ORPLACED UNDER GRATE UNnLLVVEGETATION SESTPAISHED. SITE PLAN • ,TER FABRIC MATE MAL BTVACEROLLS USE STAPLES OR WIRE RING TO ATTACH !�{e o to w L n'c al A '�R11'//I FABRIC TOW RE [`[� {[,-1E`L IL ■LLL 27C1•x+4 GAl1GEW+RE FABRIC OR EOUVNINT 150' 1 7— 1 Testing V Y MA1C , YV BURY BOTTOM OF ALTER i TX4"WOOD POSTS,STATDPRD OR MATERIAL IN 87RTTTRBNCH O ' ACC y S RO,�ti O STEEL N E UAL ALTERNATE O , '^ STEEL FENCE POSTS W (o - R FILTER FABRIC 7 GEWlR PK OS FABRIC OR EGUVALENTGROU 2-P O /�� GROUND SfiiFA.CE 6-P (�7J PROVIDE& YIwAS Efl I / GRAVEL BACKFILL IN TRENCH i2" LOCAT40N' \'8 /�'' I. AIDE BOTM SNTHE FILTER FENCE FABRIC ID THE SAFER CMN DPOSTS --- ALT SITE STEEL FENCE (v' TI "`T'�`�"�`°� Geotechnical Services FILTER FABRIC PENCE NO BB. QA/QC Services +.FILTER FABRIC SHALL BE PURCHASED IN ACOMINUDUSROLLCUTTO _ _ THE LENGTH OF THE BARRIER TOAVOWl1 SSEOFJOINTS.`MBJ�ITT Testing Services ---- - ARE NECESSARY,FILTER CLOTH SHALL BE UCEDTOGER6t A SUPPORT POST WITH A MINIMUM""OVERLAP NOSECURELY -� FASTENED AT BOTH EDSTOTFEPOST. ___ _______- G1O 2.POSTS SHALL BE SPACED A MAAM1M OFBFEET APART INDCRIVEN _�'' S SECURELY INTO ThE GRO'JNDRANMM OF%INCIESI. ---- ------- D (( \ 3.ATRENCHSHALLBEE%CAVA7EDAPPROpMATtLYeMQESW7DE AND+2 10011 Bbmberp St.SW POTENTIAL -'� IL IN liL$�IC INCHES DEEP ALONG THE LINE OF POSTS ADUPSLOPEFROMTIEBARRIER Olympia,WA 98512 INFILTRATION _- 'Y / ( fir 7 4.WHEN STANDARD STRENGTHFlLTERFN3PoCISUSED.AYNREMES Phone:(360)754-4612 INFILTRATION .:�- � SUPPORT FENCE SHALL BE FASTENED SEq.FRHYTOTIEUPSLOPESCE ---- --LOCATtON---- LOF THE POSTS ONG. IE"RES R HGRINGS.THEESTMIESDOENT11NCHOT Fax:(360)754-4848 LONG.TIE WIRES OR HOG RINGS.THE WIRESMN.L HDOB�DFNTOTHE ( ---- _ 4{/� TRENCH AMIMMUM OF 4IN0IES AND SHALL Np7p(TEDMORETNAN% i '/ gf� INCHES ABOVE THE ORIGWLGROLIDSURFACE. __--_ - { s.THE STANDARD STRENGTH FILTER FABRIC SiNlff STARED OR VAiiEn Date: 05/13/2005 _ - _ co INTO THE TRENCH.THE FABRIC SIFALLNGTE(TEDMORETHMI% -- - - VINCHES Designed by: LL _ INCHES ABOVE THE ORIGINAL GROUND S.1RFA�.RLTER FN3faC5HN1 _ _ L- 't - ^�- NOT BE STAPLED TO THEDMNGTREES Drawn by: LL CID - - - - -_ Yu 00 ��fR 8 WHEN E%TRASTRENGTH ALTER FABRIC AND CLOSER POST SPACING IS Checked by: LL - ` ,,, .! ,: USED,THE VNRE MESH SUPPORT FENCE SUCH DV1Ig :05-13-05-042 / A CASE,THE FILTER FABRIC IS STAPIIDOR WNR®CRECTLYTOTLE _�-Y(_Y____ 1 * .� .$,, < POSTS WITH ALL OTHER PRO SONS ABOVE NOIESN+PLYBNG. 500 __ /�T';f Ire(J T.FILTER FABRIC FENCES SHALL NOT BE RB gEFORPTHEIF30PE y L J ( AREA HAS BEEN PEgA/AHBJILY STABl12E3. __-_ ______- _______ EACH __________ 8.FILTER FABRIC FENCES SHALL BE INSPECi13)MM31AlELY AFTER RAINFALLL AND AT LEAST WILY DURING pROLONG®RNNFNL.ALA' ---_ -_ ____ REQUIRED REPAIRS SHALL BEMAOEIM.®IATELY. - t 7__--- GENERAL EROSION CORP LMJTFa: -------- +. EROSIOBEGINN49 SHALLIEROSION_ _ 2.EROSION CONTROL MEASL:.ES ARE NOT IIMIEDTO TIE_________________ ___ ONTHISPLAN.THE CONTRACTOR ISRESPON3&E FOR THE - - _____________ INSTALLATIONAND.CARE SANCE Of ALL EROSION CONTROLAEASIRES. -- ____ L'L'L'\\\LLL NOVLTARONOFEWSTINGORPROPOS 11%1AGEFACLRIES PROJECT NAME: `�•� `` _._________ _ SMALL BE ALLOWED.CARE STALL BETAItEN7O PREVENT MGRARCN NORTH GF SILTS TGOFFSITEIROPBTES MIKE STRAIGHT ------ _ 9 THE CONTRACTOR SMA"MATE DAILY SURYBLLMICEOF NLBROSON 345 SEAR LANE NORTH ------------------ -- -------- - SCALE'I"=50' CONTROL MEASURES AND MATE ANY NECESSARY REAM OR ADDMNS `�- --------------- --48---- -__--- TO THE EROSION CONTROL MEASURES.TECOPRRACMRSHALLFROVIDE ----------- ---_ C.I.=7 ADDITIONAL EROSION CONTROL MEASURES AS DETEM'ND7Z�ARY LILLIWAUP, WASHINGTON ' ------------------_ ----------- -- - ---------- --- DATUM ASSUMED To wMPCOiYw TMITELCOCAL Ar STATEBTOSONCI OR ANDFOR THEPROlECr ENGINEER.FAILURE - �_ _ ___ THIS IS NOT ASURVEY REGUIREMENTSMAVRESILTINgNLFBNKTESBBNGIEAE) PARCEL 323093400030 AGAINST THE CONTRACTOR ANDORPRO,ECT OWNER - ______ _ ______-___ 4.WRING THE WET SEASON(NOVEMBER TO MNRCHI ALLCISTUREED SOILS _ ____ 10 20 30 40 50 SHALL BE STABLIZED WITHIN 48 HOURS lFTER 5T I / , _ _ --_-___ _ ___- ____ CONTROL MEASURES SHALL INCUOE,BIlT NOT B: ___ - _ ___ _-_ COVERING THE EFFECTED AREA INCLUC/NG SPWL RLESNAnH / I / ____ ______ PLASTIC SEETING,STRAW.MATRNG,JUTEMATTING,STRAWMA.CH, OR WOOD CARPS.SEEdNGOF THECNSRIIRB®NREASSWLTAIE W 1 / PLACE AS WEAn6RPBifTS IS /_D_ / AQCES R,O I 1 5 LL rg EV �YERAGEEiscom ETE AREASSHNLSE 1 1 RBNRED.RESEEDED.AFD Fl3R1C12»ASREOUARED / I R 1 1 B.ROEF W G OF SOIL OFFSTE VALL NOT EENLOWED.F M rLLS / II I TRACEDOMOACOUNT+STREET.IT SVLLBERBAOVEDBYTEFUD -____ - I I I r OFTRATWORTINGDAY,ANY FIURTHHRTRACGNG OF MIDVALLTFEN �/� BE pREVQNT®BY SWB�ING OR WASHING OFTEVBFCLESMAES _____________________ _____i \1/ BEFORE ORINNG ONAO]IUJTY STREET __ _ _ 7.NO MORETHNN 500 LF OF TRENCH ON AOOANSLOPECFMORE7HNN5 PERCENT SHALL BE OF@!®ATOTETIAE 8,E%CAVATED MATERIAL SHALL SEPLACEDON TEtPHILL SIDEOFTRENCES 8.TRENCH DEWATERING DEWCES SHALL EAgSCVRG®IN A rEMSOR HAT VALL NOT ADVERSELY AFFECT FLOWING LL BEDS. HARGEDIN AMN4NR OFFSTE FROPBn1E5. SCALE:t inch 50 test +0.ALL STORM SEWER INLETS RECBMING Rl0'40M FROMTE PROJECT"NG CONSTRUCTION SHALL BE PROTECTED SOTHAT SEDIMENNADENWATER BEFORE WILL BE FILTERED BORE E NTERIING7IAE CONVEYN40E SYSTEM ^N, It ALL OFF-SITE CATCH BASINS IMMEDIATELY ADJACI NTTOTFE S17E r N SHALL BURRED AREAS ROM St LL BE SON. FIGURE 2 Q � +2.ALL DISTURBED AREAS A" BE SEE PEDORSOWBET089JRETHTION OF WORT.THE CONTRA"C.TOR SNALL A EKStSPTOBISLRTHAT N COMPLETEWTHOF THE COVAT ERAGE �DISTURBEDARES SPRONOEDaT AT 15Cp"cMIMMSHALL��ATp1MM7MU%O:' SITE PLAN �O ,,STAT�c0� MASON COUNTY PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGW Shelton, Washington 98584 �! y Oy ` �OJ 1864 DATE: June 26, 2006 INTER-DEPARTMENTAL COMMUNICATIONS �� �a 0 TO: Tammi Clark PARCEL # 32309-34-00030 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-00679 SUBJECT: Geo-Tech Report and Addendum Review NAME: Straight Mike Tammi, The Geotechnical Report and addendum to Geotechnical Report dated June 9, 2006 prepared for the proposed new single-family residence and shop located at 345 North Shar Lane near Lilliwaup has been received and reviewed by Public Works. On June 8, 2006 1 had requested an update to the May 23, 2005 Geotechnical Report along with a visit to the site to see if site conditions had changed since the May Report. The author of the addendum wrote that they are pleased to report that site conditions are identical to the conditions observed in May 2005 after visiting the site. They determined that conditions remain consistent to the conditions previously observed and reported in their geotechnical report. The May 23, 2005 report appears to satisfactorily address County requirements for Geotechnical Reporting. The report's author indicates that in their opinion that the site is suitable for the proposed project. The author goes on to say that if their analysis and recommendations are followed, they do not anticipate any onsite or offsite impact from the proposed construction. Slope stability was modeled in both static and extreme dynamic conditions. A building setback of 30 feet from the crest of the 30% or more slope to the bottom of the footing should be observed per the report. Based on the contents of the addendum and the May 2005 geotechnical report, I recommend accepting the report as satisfying the County's requirements for stability investigation and geotechnical reporting. Recommendations and Comments contained in the report should be incorporated into the site development plans and made conditions for permit issuance. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Sind rely, John Sliva rograms Engineer 6 LIB aooV 00� -7 9 GEOTECHNICAL VESTING LABORATORY MIKE STRAIGHT RECEI V P.O. Box 149 ED LILLIWAUP,WA 98555 JUN 2 2 24 RE: DAMAGE ASSESSMENT SITE: 345 SHAR LANE NORTH C0# yp/l��'"'��UU C LILLIWAUP, WA 98555 I� RKS GPS LOCATION: N47029.670' W 123°04.514' PARCEL NUMBER: 323093400030 DATE: 06/9/2006 Mr. Straight: As requested, we have conducted a follow up site visit to determine if conditions have changed since May 2005. We are pleased to report that the site conditions are identical to the conditions observed in May 2005. The recent trenching of utilities along the access road is essential to the multiple parcels served by Shar Lane. Dry raveling of the cut slopes adjacent to Shar Lane is common for well-rounded and unconsolidated glacial drift. Along Shar Lane, vegetation limits are similar to earlier conditions and only minor erosion was observed. After utility construction,no further trenching is anticipated; a roadside ditch will control stormwater. The proposed building location remains undisturbed and ready for construction. No impact has occurred to the southern slope. We determine that conditions remain consistent to the conditions previously observed and reported in our geotechnical report. 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. , Respectfully Submitted, GEOTECHNICAL TESTING LABORATORY Harold Parks, L.E.G., L.G. Senior Engineering Geologist 10011 Blomberg Street SW,Olympia, WA 98512 1 Phone#:(360)754-4612 Fax#: (360)754-4848 3TAr�®� MASON COUNTY IL `s A o PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER ° S N Shelton, Washington 98584 v N V �aJ O' M4 DATE: June 8, 2006 INTER-DEPARTMENTAL COMMUNICATIONS TO: Tammi Clark PARCEL # 32309-34-00030 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-00679 SUBJECT: Geo-Tech Report Review Hold NAME: Straight Mike Tammi, The Geotechnical Report prepared for the proposed new single-family residence and shop located at 345 North Shar Lane near Lilliwaup is still under review by Public Works. On June 7, 2006 1 had written a report stating that the May 23, 2005 Geotechnical Report would be acceptable if the author of that report certified that the report can still be used in lieu of a new Geotechnical Report. Today I am asking for a re-evaluation of that report and any new recommendations. Today I was in the area and visited the site. I noticed that underground utilities were being run up Shar Lane North. The utilities were being placed in the shoulder of that access road coming up the hill and were being dug into the cut that is below the property discussed in this report. Walking the road to the west I noticed some erosion on the bank down the road at a switchback. A neighbor had mentioned a homeowner on a lot above that switchback had some ground movement on that lot. She did not say where or what kind, erosion, sluffing, etc. I also went up to the site and noticed stakes for the proposed shop. The set back for the proposed shop looked good. My concern is the future home set back and is it going to be placed where your first Geotechnical Report expects? A drawing I received today from planning dated May 9, 2005 has the home placed more west. I know that geology does not change over night. I am requesting that The Geotechnical Report be re- evaluated to look at: 1. Slope stability for static and seismic due to work on the access road below the site. This was excavating three feet down in the toe of the cut bank around elevation 450. 2. Are new setbacks required? 3. Physically will the structures fit with the set backs required? 4. Check the area once again for geological feature changes. 5. Any changes in recommendations and conclusions. The Geotechnical Report Review is on hold and no further action will be taken by Public Works until we receive what is requested above. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Sincerely, I /I P John Sliva `Programs Engineer RECEIVED MASON COUNTY PUBLIC WORKS WORK ORDER MAY 19 2006 Permit #: � c/ MAS0N000NT�~�-�v2-�j n� - L)(�'J MKS Date: Requested by: Authorized by: Type of Work: Public Works employee in charge: U darn TOT 5 CHARGE TO: C Name: � Ali �lZli� Billing Address: Phone: WORK PERFORMED: Employee: ts: S�+✓� ^at,J S L/�/14 Date: /-7 l C f, a Hours: Hourly Rate: Total: �[/ c�"'3 � CIr ACCOUNTS RECEIVABLE INFO: Billed Date: Invoice #: Amount Billed: Receipt # Date: Amount Paid: GEOTECHNICA L 'TESTING LABORATORY MIKE STRAIGHT P.O. Box 149 LILL11VAUP,WA 98555 RE: DAMAGE ASSESSMENT SITE: 345 SHAR LANE NORTH LILLIWAUP,WA 98555 GPS LOCATION: N47029.670' W123004.514' PARCEL NUMBER: 323093400030 DATE: 06/9/2006 Mr. Straight: As requested, we have conducted a follow up site visit to determine if conditions have changed since May 2005. We are pleased to report that the site conditions are identical to the conditions observed in May 2005. The recent trenching of utilities along the access road is essential to the multiple parcels served by Shar Lane. Dry raveling of the cut slopes adjacent to Shar Lane is common for well-rounded and unconsolidated glacial drift. Along Shar Lane, vegetation limits are similar to earlier conditions and only minor erosion was observed. After utility construction, no further trenching is anticipated; a roadside ditch will control stormwater. The proposed building location remains undisturbed and ready for construction. No impact has occurred to the southern slope. We determine that conditions remain consistent to the conditions previously observed and reported in our geotechnical report. 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. Respectfully Submitted, GEOTECHNICAL TESTING LABORATORY /1 Harold Parks, L.E.G., L.G. Senior Engineering Geologist AW 10011 Blomberg Street SW, Olympia, WA 98512 1 Phone #: (360) 754-4612 Fax#: (360) 754-4848 sTArFo� MASON COUNTY PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER a Shelton, Washington 98584 Y ti Z y '�CjJ ya0 7864 DATE: June 7, 2006 INTER-DEPARTMENTAL COMMUNICATIONS TO: Tammi Clark PARCEL # 32309-34-00030 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-00679 SUBJECT: Geo-Tech Report Review NAME: Straight Mike Tammi, The Geotechnical Report prepared for the proposed new single-family residence and shop located at 345 North Shar Lane near Lilliwaup has been received and briefly reviewed by Public Works. The Geotechnical Report was written May 23, 2005. We need a more recent report preferably done within the last six months. The consultant who did the Geotechnical Report dated May 23, 2006 can send a letter certifying that the report can still be used in lieu of a new Geotechnical Report. A PE stamp would be required on that letter. This can be handled as an addendum to the report if the same report is used. The report appears to satisfactorily address County requirements for Geotechnical Reporting. The report's author indicates that in their opinion that the site is suitable for the proposed project. The author goes on to say that if their analysis and recommendations are followed, they do not anticipate any onsite or offsite impact from the proposed construction. Slope stability was modeled in both static and extreme dynamic conditions. A building setback of 30 feet from the crest of the 30% or more slope to the bottom of the footing should be observed per the report. Adequate erosion and sediment control features need to be implemented during land disturbing activities to protect neighboring properties and State waters from adverse stormwater runoff impacts. The migration or release of silty water or mud from the applicant's property will be considered a violation of County and State water quality protection regulations. Based on the contents of this report, I recommend accepting this report as satisfying the County's requirements for stability investigation and geotechnical reporting after we receive an addendum to this report from the author certifying that the report can still be used in lieu of a new Geotechnical Report. If the addendum has new comments and/or recommendations, those recommendations or comments will need to be reviewed before final acceptance to move forward with this project. Recommendations and Comments contained in the report should be incorporated into the site development plans and made conditions for permit issuance. The Geotechnical Report Review is on hold and no further action will be taken by Public Works until we receive what is requested above. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Sin a ly, "John Sliva Programs Engineer Geotechnical Report 345 Shar Lane North Lilliwaup, WA Prepared for: Mike Straight by Geotechnical Testing Laboratory Olympia, Washington May 23, 2005 GEOTECHNICAL TESTING LABORATORY MIKE STRAIGHT P.O. Box 149 LILLIWAUP, WA 98555 RE: GEOTECHNICAL REPORT 345 SHAR LANE NORTH LILLIWAUP, WA 98555 PARCEL 323093400030 N47029.670' W 123°04.514' INTRODUCTION This report summarizes the results of our geotechnical consulting services for the proposed single-family residence and shop to be located near Colony Surf, approximately 3.0 miles northeast of Lilliwaup,Washington. The 2.7-acre site is shown relative to the surrounding area on the Vicinity Map, Figure 1. Our understanding of the project is based on our discussions with you and our explorations and review of the site. We understand that the parcel is to be developed with a single-family residence. The site will be accessed by a driveway from Shar Lane off Eagle Creek Road. In general, grading will consist of the excavation of the foundation. footings, and driveway. A& ?� t The site slopes south from a level area toward the Hood Canal. The steepest slope measured onsite was in excess of 100 percent along roadside cuts. Therefore, Mason County requires that a geoteclimcal report be prepared in accordance with the Critical Areas Ordinance. 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 is therefore providing geologic and hydrogeologic services for the project. Specifically, our scope of services for this project will include the following: 10011 Blomberg Street SW, Olympia,WA 98512 1 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY 1. Review the available geologic,hydrogeologic, and geotechnical data for the site area. 2. Conduct a geologic reconnaissance of the site area and surrounding vicinity. 3. Investigate shallow subsurface conditions at the site by observing the exposed soil and reviewing published well logs. 4. Evaluate the landslide and erosion hazards at the site per the Mason County Critical Areas Ordinance regulations. 5. Provide 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 erosion control measures. SITE CONDITIONS SURFACE CONDITIONS The proposed building site is located in an area of moderate residential development in the glacial uplands overlooking the Hood Canal. The site has southern exposure. We conducted a reconnaissance of the site area on May 9, 2005. Site elevations range approximately from 400 to 522 feet. A septic system is proposed onsite. The site will be served by a community well. ;/fit-..., '�4�?f a•�+ t rat .a . The proposed building location had been previously cleared of vegetation. The site slopes are vegetated with a well- mixed variety of vegetation common to the Northwest. The vegetation includes fir, alder, hemlock, and madrone trees as well as Scot's broom, bracken ferns, sword ferns, manzanita, rhododendron, salal, huckleberry, foxglove, blackberry,and grasses. The only exposed soil is along the access driveway road cuts. At the time of the site visit, we observed no evidence of active surface erosion at or around the proposed building location. Slope instability was not observed near the proposed building location. Active sloughing and raveling was observed along the road cuts. Onsite trees were observed straight and vertical. Surface water flow was not observed at the time of our reconnaissance. Groundwater was not encountered or observed onsite. The groundwater depth was not encountered and is presumed to be deep. The general topography of the site area indicates that drainage is toward the south. 10011 Blomberg Street SW, Olympia,WA 98512 2 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SITE GEOLOGY The site is generally situated within the Puget Sound glacial upland. The existing topography, as well as the surficial and shallow subsurface soils in the area, are the result of the most recent Vashon stade(stage)of the Fraser glaciation that occurred between about 10,000 and 12,000 years ago, and weathering and erosion that has occurred since. A description of the surficial soils is included in the "Site Soils" section of this report. In general, the soils are composed of glacial material. SITE SOILS The Soil Survey of Mason County, USDA Soil Conservation Service (1960)has mapped the site soils as Hoodsport stony sandy loam, 5 to 15 percent slopes(Hg). The survey reads: This soil differs from Hoodsport gravelly sandy loam, 5 to 15 percent slopes, in having many large, irregular stones and boulders scattered over the surface and in the soil and parent material. This lessens the desirability of this soil for any use. The Geologic Map of Washington - Northwest Quadrant (2002) has mapped the site geology as glacial till deposits (Qgt) of continental glacial origin. The report reads: g0l­ 7-111 - Unsorted, unstratfiied, highly compacted mixture of clay, silt, sand, gravel, and boulders deposited by glacial ice; may contain ,1 interbedded stratified sand, silt, and gravel. Includes part of the Vashon Drift undivided. 10011 Blomberg Street SW, Olympia,WA 98512 3 Phone#: (360)7544612 Fax#: (360)7544848 GEOTECHNICAL TESTING LABORATORY F; e The Geologic MaD of North Central Mason County, Wa has Lodgement till f4tMjRdLment till is111111Wur EU U1d,7 — SUBSURFACE EXPLORATIONS Subsurface conditions at the site were evaluated by observing the exposed building site soil and reviewing available well logs. Depth to competent soil is approximately 6 inches throughout the proposed building location. Static groundwater is presumed deep and beyond the scope of this project. ±,Fy f r_fr F 10011 Blomberg Street SW, Olympia,WA 98512 4 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY SUBSURFACE CONDITIONS In general, undisturbed dense Hoodsport gravelly sandy loam was observed throughout the proposed building location. Groundwater seepage was not observed onsite. Based on the site topography and the nature of the near surface soil, seasonally perched groundwater conditions are not expected during periods of extended wet weather. i SLOPE STABILITY Slopes in excess of 100 percent were observed onsite. Since UM slopes of 40 percent or greater with 10 feet or more of vertical relief occur on portions of the site, Mason County requires that B""' a geotechnical report be completed according to the Critical ���`- Areas Ordinance. UM The near-surface soils are in a dense to very dense condition , `�� Ayock Pt except at the ground surface. The surficial soils are generally in ; a►w 8 a medium dense condition. i i In general, the undisturbed native soils of the site consist of a mixture of variable amounts of sand, silt,and gravel. These soil materials are in a dense condition except where they have been disturbed by weathering activity. These soils are generally . stable relative to deep-seated failure. Sloughing, undercutting, Lks and active erosion were observed along the road cuts. V's urs Weathering, erosion, and the resultant sloughing and shallow ;` SmIc 1:24,000 landsliding are natural processes that can affect steep slope u's areas. Instability of this nature is typically confined to the upper weathered or disturbed zone, which has been disturbed and has a = _ 1 lower strength. No surface water or active erosion was ,^ , '`'� observed at the proposed building location. 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. Erosion in steep slope areas such as this can be reduced by encouraging vegetation and discouraging runoff from the steep slope. Erosion control recommendations for the sloping areas are provided in the "Erosion Control'section of this report. 10011 Blomberg Street SW, Olympia,WA 98512 5 Phone#: (360) 7544612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY r , t 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 building location slopes are stable relative to deep- seated instability and will not be affected by the proposed structure if our recommendations are respected. The proposed structure will not undermine adjacent structures. 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 minimized in such a manner as to prevent harm to property and public health and safety, and the project will cause no significant environmental impact. In general, the Hoodsport soils observed at the site may be suitable for use as structural fill material. 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 spread footings may be utilized at the site for support of the structure. . A vapor barrier is recommended for all slab-on-grades. Pertinent conclusions and geotechnical recommendations regarding the design and construction of the proposed single-family residence are presented below. LANDSLIDE— EROSION HAZARD AREAS CLASSIFICATION The Mason County Critical Areas Ordinance (17.01.100) defines a landslide hazard area as one containing slopes equal to or greater than 40 percent with more than a 10-foot vertical relief The southeastern slope is in excess of 40 percent and the vertical relief is in excess of 10 feet. Based on this, this site does meet the technical criteria of a landslide hazard. The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977) describes the southern site area as Class 3. Class 3 is described as: 10011 Blomberg Street SW, Olympia,WA 98512 6 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Areas inferred to be unstable because slopes, generally greater than 15 percent, are underlain by weak, unstable materials in which old or recently active landslides have occurred. Includes areas of sand and gravel on top of impermeable silt and clay, mostly along steep valley sides. The Mason County Critical Areas Ordinance(17.01.104)defines an erosion hazard area as: 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') e. Harstine gravelly sandy loam ("Hb') d. Kitsap silt loam ("Kc') The soils at the site are mapped as Hoodsport gravelly sandy loam (Hg). This site does not meet the technical criteria of an erosion hazard area. SLOPE STABILITY Based on our field observations, explorations and our experience with the soil types encountered on the property,we conclude that although portions of the slopes on the lot exceed 100 percent, the site is generally stable relative to deep-seated failure in their present configuration. The Coastal Zone Atlas, Volume 9, Mason County (MA-3) maps the site as Vashon glacial till (Q,). The till is a tough, dense material of low permeability. It provides excellent foundation support. The site slope stability is described as "unstable"at the building site. To prevent minor sliding, uncompacted fill material and any underlying vegetation shall be removed in order to construct the foundation. 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. i As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural processes that affect slope areas. 10011 Blomberg Street SW, Olympia, WA 98512 7 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 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 destabilizing 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. A building setback from landslide hazard areas is required unless evaluated and reduced by an engineering geologist or a licensed professional engineer. Based on our geotechnical evaluation of the site and our experience in the area, a building setback will be needed for this lot. 30% or more) slope to the bottom of the footing should setback otherwise be observed. The building setback may be measured from the bottom of the footing to the face of the steep slope in accordance with the 2003 International Building Code(IBC). Peak Shear Stress vs. Normal Stress Sandy Loam 3000 42° 2500 c a 2000 .40 1500 R m L fA Y 0 1000 d 500 +1/4 ton -s-12ton -�1 ton 0 0 500 1000 1500 2000 2500 30M Normal Stress(psf 10011 Blomberg Street SW, Olympia, WA 98512 8 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Slope stability was modeled using the GEO-SLOPE/W program (version 5.20) in both static and extreme dynamic conditions (ce = 0.3). Factors of safety were determined using Straight Site--Slope A Bishops, Janbu, and the Analysis Method: Morgenstern-Price Morgenstern-Price methods. The Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vertical glacial till was determined to have a unit weight of 131 pcf, cohesion of 200 psf, and a shear angle (�) of 42°. Under static conditions, the slopes were stable to shallow failure. Under dynamic loading, the 3328 '•' '�� computations demonstrated that the '• ,," . . l slope is not susceptible to surficial raveling or deep-seated failure. The following figure illustrates the moment factor of safety for slope "A" 540 .'.'. • 1.2s under the existing conditions. The 520 figure is the solution of greatest t 5oo concern and exhibits the need fora y 480 Hoodsport building setback of 30-feet from the ; 460 Unit Weight:131 h crest 30%or more of the slope. aao Cohesion:=00 ( ) pe• W Phi:42 420 400 0 25 50 75 100 125 150 175 200 225 250 275 300 325 360 375 400 Distance(ft) As previously discussed, weathering, erosion and the resultant surficial sloughing and shallow landsliding are natural processes that affect slope areas. Surficial raveling and sloughing was observed onsite along the oversteepened roadside cut. To manage and reduce the potential for these natural processes, we recommend the following: 1. 2. "b� r ag t�>a1I"._ Now- 3. == re areas as'long as the '+" 'cam �Nr .,i'%�' n►' .7.i "� ".. •- I t r ♦l ' - T _ a 10011 Blomberg Street SW, Olympia,WA 98512 9 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SEISAHC—LIQUEFACTION HA7ARD According to the Seismic Zone Map of the United States contained in the 2003 International Building Code (IBC), the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g). 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 low liquefaction potential. The Site Class Map of Mason County, Washington by Palmer, Magsmo, Bilderback, Poelstra, Folger, and Niggemann (September 2004) maps the site area as site class C to D. Site class C is a very stiff soil or soft rock and site class D is a stiff soil. 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, as defined by Table 1615.1.1 (IBC). This is based on the range of SPT (Standard Penetration Test) blow counts and/or probing with a %Z-inch diameter steel probe rod. The shallow soil conditions were assumed to be representative for the site conditions beyond the depths explored. Based on our review of the subsurface conditions, we conclude that the site soils are only mildly susceptible to liquefaction. The near-surface soils are generally in a dense condition and the static water table is located well below the surface. 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. EROSION CONTROL 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 and limited to the active construction areas. Yard landscaping around the home is permissible,but understory growth on the slopes should be encouraged as much as possible as a deterrent to erosion. Trees located on steep slopes may be removed only if the stumps remain to deter erosion. �s. but not be limited to, silt fences, berms and swales with ground cover/protection in exposed areas. A typical silt fence detail is included on Figure 2. Any re-contouring of the site will create a need for erosion control measures as listed above. EARTHWORK 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 stripping on the order of 6 to 12 inches will be necessary to remove the root zone and surficial soils containing organics. Areas with deeper, unsuitable organics should be expected in the vicinity of depressions or heavy vegetation. Stripping depths of up to 18 inches may occur in these areas. These materials may be stockpiled and later used for erosion control and landscaping. Materials that cannot be used for landscaping or erosion control should be removed from the project site. 10011 Blomberg Street SW, Olympia,WA 98512 10 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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. We recommend that trees be removed with the roots, unless located on a slope. Excavations for tree stump removal in any building area should be backfilled with structural fill, compacted to the density requirements described in the"Structural Fill"section of this report. 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. 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 90 percent of MDD (maximum dry density as determined in accordance with ASTM D-1557) to within 2 feet of subgrade and 95 percent MDD in the upper 2 feet. The appropriate lift thickness will depend on the fill characteristics and compaction equipment used. OW 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 5 percent (by weight) passing the No. 200 sieve based on that fraction passing the'/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. 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. Ow y, 10011 Blomberg Street SW, Olympia,WA 98512 11 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SUITABILITY OF ONSITE SOILS AS FILL Onsite soils may be considered for use as structural fill. In general, the native soils (sand, loam, 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. 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 will likely 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. Flatter cut slopes will be necessary where significant raveling or seepage occurs. Surface drainage shall be directed away from all slope faces. All slopes should be seeded as soon as practical to facilitate the development of a protective vegetative cover or otherwise protected. FOUNDATION SUPPORT Where foundation elements are located near slopes of 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 footings and continuous wall footings to meet IBC. 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. 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 0.40 be used to calculate fiiction between the concrete and the underlying soil. Passive 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 sub-grade during construction could result in larger settlements than predicted. 10011 Blomberg Street SW, Olympia,WA 98512 12 Phone#: (360) 7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 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 minimum 6- inch thickness of coarse sand and/or gravel containing less than 3 percent fines (by weight). The drainage material should be placed in one lift and compacted to an unyielding condition. A synthetic vapor barrier may 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. RETAINING WALLS Retaining walls may be utilized on the sloping portion of the site to retain fill material. The lateral pressures acting on the subgrade and retaining walls will depend upon the nature and density of the soil behind the wall. It is also dependent upon the presence or absence of hydrostatic pressure. If the adjacent exterior wall space is backfilled with clean granular, well-drained soil (washed rock), the design active pressure may be taken as 0.40 (coefficient). This design value assumes a level backslope and drained conditions as described below. Retaining walls located on or near the toe of a slope that extends up behind the wall should be designed for a lateral pressure, which includes the surcharge effects of the steep slope in proximity to the wall. Although not expected at this site,the following data is provided for planning purposes. For an irregular or composite slope, the equivalent slope angle may be determined by extending a line upward from the toe of the wall at an angle of 1 to 1 (Horizontal to Vertical) to a point where the line intersects the ground surface. The surcharge effects may be modeled by increasing the equivalent fluid pressure for flat ground by the percentage given in the following table: SLOPE INCLINATION: EQUIVALENT FLUID PRESSURE Slope Angle Percent Increase Equivalent Fluid Pressure Horizontal 0% 35 pcf 3H:1V 25% 44 pcf 2H:1V 50% 53 pcf 1H:1V 75% 61 pcf If the walls are greater than 4 feet in height, exclusive of the footing, additional design considerations should be applied. Positive drainage, which controls the development of hydrostatic pressure, can be accomplished by placing a zone of coarse sand and gravel behind the walls. The granular drainage material should contain less than 5 percent fines. The drainage zone should extend horizontally at least 18 inches from the back of the wall. The drainage zone should also extend from the base of the wall to within 1 foot of the top of the wall. The drainage zone should be compacted to approximately 90 percent of the MDD. Over compaction should be avoided as this can lead to excessive lateral pressures. A perforated PVC pipe with a minimum diameter of 4 inches should be placed in the drainage zone along the base of the wall to direct accumulated water to an appropriate discharge location. 10011 Blomberg Street SW, Olympia,WA 98512 13 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY We recommend that a non-woven geotextile filter fabric be placed between the drainage material and the remaining wall backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage zone can, with time, reduce the permeability of the granular material. The filter fabric should be placed in such a way that it fully separates the drainage material and the backfill, and should be extended over the top of the drainage zone. Lateral loads may be resisted by friction on the bases of footings and as passive pressure on the sides of footings and the buried portions of the wall. We recommend that an allowable coefficient of friction of 0.40 be used to calculate friction between the concrete and the underlying soil. RETAINING WALL ALTERNATIVES Typically, block wall systems are more cost effective for long-term walls than the other options. Specific design criteria for these options can be provided at your request by the block manufacturers. SITE DRAINAGE All ground surfaces, pavements, and sidewalks should be sloped away from the residence and associated structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight-lined to an appropriate infiltration area. We recommend that conventional roof drains be installed. Footing drains shall be installed for the single-family residence. 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. the western portion of the site by IMMe. Drainage control measures are included on Figure 3. Onsite irrigation to lawn areas should be closcl, monitored. We do not expect any adverse affects on the recharge condition of the groundwater system. 1- S 10011 Blomberg Street SW, Olympia,WA 98512 14 Phone#: (360) 7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY LIMITATIONS We have prepared this report for Mike Straight and members of his design team,to use in the design of a portion of this project. The data used in preparing this report, and this report, should be provided to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and interpretations are based on data from others and our site reconnaissance, and should not be construed as a warranty of the subsurface conditions. This report is quantified as a micro-study and not a macro-study. Geotechnical Testing Laboratory and its personnel cannot be responsible for unforeseen and widespread geologic events (such as earthquakes, large-scale faulting, and mass wasting)beyond the scope of this project. Variations in subsurface conditions are possible and may occur with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient consultation with our firm during construction should continue, to confirm that the conditions encountered are consistent with those indicated by our observations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork and foundation installation activities comply with our specifications. If our analysis and recommendations are followed, we do not anticipate any onsite or offsite impact from the proposed construction. It is our conclusion that potential landslide hazards can be overcome so as not to cause harm to property, public health and safety, or the environment. The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. If there are any changes in the loads, grades, locations, configurations or types of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. �e o� Was hl� Respectfully submitted, GEOTECHNICAL TESTING LABORATORY yti� f0 Harold Parks, L.G., L.E.G. 827 Senior Engineering Geologist HAROLD PARKS &,rf, 7-3i— o,s' 10011 Blomberg Street SW, Olympia,WA 98512 15 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY Vicinity Map �qf T 47 T I's arm* Stedts,�'� L1.0 Wit H(D SID j. vi "v /a 'W� Fi gure 1 10011 Blomberg Street SW, Olympia,WA 98512 Phone#: (360) 754-4612 Fax#: (360) 754-4848 1/2 INCH MINIMUM DIAMETER STEEL ROD (STRAP)CLAMPED SECURELY TO PIPE CORRUGATED TIGHTLINE 4 INCH 0 MINIMUM,6 INCH SUGGESTED � : Sp C/70 F F Ty'� :ice•1;..:._ . - .:s{<i �s-tom �' .:..r.; v,-rri-�":<'sif.�e•,' "Xa'"'i -h- -:i.�_— -a:.�ti,'f.,!:y`�u yr...j.1 �^e y`.'i. _.•_.�ti:♦ ;...:•r._.,:.: a:1'-.ice`i•:.;`. TIGHTLINE ANCHORED WITH TWO, 3 FOOT REBAR LENGTHS OR BOLTS. FLARE END SECTION y� QUARRY SPALL �!'"�'` <� OR ENERGY DISPERSION DEVICE . . .. �: 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 wo.be st sw FIGURE 3 QA/QC Services Olympia, e:seWo)7�1Y Testing services Fax(360)754-4848 Not to scale DRAINAGE DETAILS FILTER FABRIC MATERIAL BY WADE ROLLS USE STAPLES OR WIRE PoNGTOATTAQI Geote c h nic al A FIC WIR E NE 7'X77(u GAUGE WWE FABRIC OR EQUVNBNf 1501 Testing T-P S_pSURFACE Laboratory T- 6 MAX Q O / (�\_ 70(A'WOOD POSTS,STMDITDOR BURY BOTTOM OF FILTER ACC C S R OA O BETTER OR EQUAL AL78*ATE MATERIAL IN 8'X177RENCH '^ STEEL FENCE POSTS (.0 _ FILTER FABRIC P O S E D T 13RIC GAUGEVALE O �� FABRIC OR EQUIVALENT T P EPTIC '"" GROUNDS SURFACE s LOCATION 8 IL INS PROVIDE]THSI WASH® GRAVEL BACKFILL IN TRENCH 17 it AND ON BOTH SDESOF RLTER FENCE FABRIC ON THE Sl.RFACE 8'MIN C TI 2*W WOODPOSIS MT STEEL FENCE POSTS Geotechnical Services - FILTER PABILOPBICPNOI�: QA/QC Services 1.FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF THE BARRIER TOAVOIDUSEOF JOUTS.WENJ01NTS Testing Services _ ARE NECESSARY,FILTER CLOTH SHALL BE SAICEDTOGET ER OALY AT - -- ��' ASUPPORT POST WITH AMINIMUM BINCH OVERLAP MDSEQIR6Y 101 FASTENED AT BOTH ENDS TO THE POST ---I- y ._--- OPOS D 2.POSTS SHALL BE SPACED AMAXIMUM OFBFffT MART AND DRIVEN ` SECURELY INTO THE GROUND(MNMr M OF 301NCHE51. POTENTIAL 9 NCHESDEEPALONGTMeurEOFP°PR°STS NDUPELO�NATE7TEB°`AA'RR2ER OlymI Blomberg St.SW INFILTRATION - --"'B IL ITV Olympia,WA 98512 ----- --INFILT AT O 4 SU STANDARD STRENGTH FABRIC TO A'MREM51 L --- SUPPORTFENCTS USINGHBEFASTENEDSETAPLETOhEtIINCHSDE Phone:(360) -4-4612 --'� O LONG, IRE USING HEAW RINGS. THE REST ILLEXIASTMINCM Fax:(360)754-4848 LONG,TIE WIRES OR HOG RIHGS.TIEVARESHALE%i@DIMOTHE - _ INCHES ABOVE OF<NAL GROUND AND FWLNOT EXT@DMORE TUNA 38 _ - INCHES ABOE THE ORIGINAL GROUND SJRFACE. _�. S.THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPIEDOR"RED Date: 05/13/2005 TO THE FENCE AND 20INCHES OF FAE RCS AL BEEKrE DED - - _ __-- -- -_-- INTOTETRENCN THE FABRIC SHALL NOT EXTEDMORE THAN 35 Designed by: LL -- -- INCESABOE THE ORIGINAL GROUND SURFACE FlLTHR FN3PoCSW1 N (� NOT BE STAPLED TOTEEbSRNGTREES Drawn by: LL -_ ----______ ! 8.WHEN EXtRA.STRENGTH FILTER FABRIC AND CLOSERPOST SPACING Is Checked by: LL ----__-____-- y USED.THE VARE MESH SUPPORT FENCE MAP BE BUMNATED.IN SUQL 500 �' \� ACASE,T FILTER FABRIC ISSTAPLEDORWRMC'RB LYTOTE Dwg#:OS-13-05-042 E POSTS WITH ALL OTHER PROVISIONSOR ABOVE NOTESAPPLYING. --- 7.FILTER FABRIC FENCES SHALL NOT BE REMOVED TFORE THEUIOPE AREA HAS BEEN PERMANENTLY STA IUZEO. 8.FILTER FABRIC FENCES STALL BE INSPECTEDIM.EEIATELY AFTER EACH RAINFALL AND AT LEAST DAILY WRING PROLONGED RAINFALL ANY -_ ---- REQUIRED REPAIRS STALL HE MADE IMEOATELY. -_-_ ------ - ----------�- -_- ---------------------------- ________ _____—_-__ ____ GENERAL EROSION CONTROL NOTES: 1 EROSION CONTROL MEASURES SHALL BE N PLACE PRIOR TO THE BEGIN4 SHALLHING OF INSPECTCONSTRUCTION.TE AND APPROVETHE 9NST OF N®R ND TE COUNY EROSON CONTROL MEASURES PRIOR TO EEGIN ING CONSTRUCTION. -- --_ ______________ _---_________ ___ 2.EROSION CONTROL MEASURES ARE NOT UMTEDT011E REMS ONTHISPLATHE CONTRACTOR SRESPONSIELE OR THE � NSTALLA ON I F AND MA NTN NANCE OF ILL EROSONCONTROL MEASURES -------'--------------- -=---------- '-- NO SSHASiL`BEKLOWED CARRESHAL OR LLLBET°POSEDTAAM o"P��MGRAATON PROJECT NAME: ---------------------------------- - ------ ---- NORTH OF SILTS TO OFFSTEPR°PERRES MIKE STRAIGHT -- __ ------------ ---- 3.THE CONTRACTOR STALL MAKE DAILY S1RVEllANCE OF ALL EROSION--------------------- ---- SCALE 1"=50' CONTROLMEASU 345 SHAH LANE NORTH 4 - TOT E EROSONCONTROLMEASURES.TEOONTRRAACTORSALPRONOE _ _ ------------- -- C.I.=z BYADDITIONAL COUNTY CONTROL MEASURAND/OR THE PROJECT EN INEENECESSARY �-- ---------------------�------- DATUM ASSUMED BfTHECOUNiY1NSPECiORMID'°RTERRQECTENGIH�i FNLIFRE LILLIWAUP, WASHINGTON - ------------- COMPLY PARCEL 323093400030 --------------- ------------ ____________ _ THIS IS NOT ASURVEY REQUIREMENTS ❑MILPENALTIES4ER LEA® ____________ ____________ ___ AGAINST THE CONTRACTORMLYOR PROJECT - ----------------- -'-_------__ --' / --- -___ -____ MD 20 30 b 50 4.SHALLGTHEWET SEASONWIT INOVEMBER HIN 48 HOURS AFTERpIINLp STURBED SOILS ____ _______ _---�- ____ CONTROL EASURSTABILIRES SHALL INCLUDE.BUT NOT MT®TOFWORK.EROSION - ,- ------- ------------ Revisions: / __ COVERING THE EFFECTED AREA LING,J NG SOIL G,STRAW yy� / / PLASTIC SHEETING,STRAW MATTING,JLIfE MATTING,STRAW MACH, '--' __ /W 1 / / / / / - / -- OR WOOD CHIPS.SEEDING OF THEpSRU+I�MFA59RNLTAIE �T1///��� 1- PLACE AS WEATHER PERMITS. A C�T\ / ALL SEEDED OR SODDED AREAS SHALL BE CHECKED REGULARLY TTT ES O I 1 TO MAKE SURE VEGETATIVE COVERAGE ISCOMEIE.AREASSALLBE / / / / REPAIRED,RESEEDED.AND FERMUTUDASREOURED. _ --_ _ _-- - 7 U 1 8.TRACKED ON SOIL OFFSTE WILL NOT BE ALON®.IF AMOVED SOIL IS __ / 1 :: OF THADO WORKING TO ACDAY AN FURT.ITSVIL 13E CKNGO MUDW LT ED EN ______________ _-��--_ �y OFTHATW°RMNGDAY. MNGORWA94 IOGNGOFMDVATRES BE PREENTED BY SWEEPING OR WASMNG OFTE EHICiESTRRES BEFORE DRIVING ON A COUNTY STREET. 7.NO MORE THAN SOD LF OF TRENCH ON A DOV/NSLOPE OF MORE THAN 5 PERCENT SHALL BE OF@EI AT ONE TIME 8.EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SIDE OF TREQES. 9.TRENCH DEWATERI NG DEVICES STALL BE DISCHARGED IN A MANNER THAT WALL NOT ADVERSELY AFFECT FLOWING STREAMS.ORNNAGESYSTEMS OR �,�N.�� ,,A, c^feet PROPERTIES SCALE:1 inch=W root 10.ALL STORM SEWER INLETS RECEIVING RUNOFF FROM THE PROJECT DURING ^ CV CONSTRUCTION SHALL BE PROTECTED 50 THAT SEDIMENT-LADEN WATER tl/ WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM r- N T1 ALL OFF-SITE CATCH BASINS IMMEDIATELY ADJACENT TO THE SITE BE ECTED ROM 0 � SHALL DISTURBED AREAS HALL SE SEE FIGURE 2 Q 12.ALL DISTURBED AREAS SHALL BE SEEDED ES ONSEL UPON C RETHAT N r- OF WORK.THE CONTRACTOROF SDIKLBE DISTURBED OVIDED THAT COMPLETE COVERAGE OF THE DSTURIID AREAS ISPROMLm 6THAT GROWTH OF THE VEGETATION ISESTAEUSHED. 13 CATCH DERSGRATELRITLLVDEGETAIIONISESTASUS ED SITE PLAN RECEIVED MASON COUNTY PUBLIC WORKS WORK ORDER MAY 19 20% Permit#: LDJ_V n _00(A j MASONCOUNTY"wwMKS Date: Requested by: Authorized by: Type of Work: VS121i,j) Public Works employee in charge: l an IT06 S. CHARGE TO: 1 Name: It kQ Billing Address: Phone: f WORK PERFORMED: Employee: a, vil Date: L l l a L Hours: / S Hourly Rate: 3L. Total: ACCOUNTS RECEIVABLE INFO: Billed Date: Invoice #: Amount Billed: Receipt # Date: Amount Paid: Ono Geotechnical Report 345 Shar Lane North Lilliwaup, WA Prepared for: Mike Straight by Geotechnical Testing Laboratory Olympia, Washington May 23, 2005 GEOTECHNICAL TESTING LABORATORY MIKE STRAIGHT P.O. Box 149 LILLIWAUP, WA 98555 RE: GEOTECHNICAL REPORT 345 SHAR LANE NORTH LILLIWAUP, WA 98555 PARCEL 323093400030 N47029.670' W 123°04.514' INTRODUCTION This report summarizes the results of our geotechnical consulting services for the proposed single-family residence and shop to be located near Colony Surf. approximately 3.0 miles northeast of Lilliwaup, Washington. The 2.7-acre site is shown relative to the surrounding area on the Vicinity Map, Figure 1. Our understanding of the project is based on our discussions with _you and our explorations and review of the site. We understand that the parcel is to be developed with a single-family residence. The site will be accessed by a driveway from Shar Lane off Eagle Creek Road. In general, grading will consist of the excavation of the foundation, footings, and driveway. a The site slopes south from a level area toward the Hood Canal. The steepest slope measured onsite was in excess of 100 percent along roadside cuts. Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Critical Areas Ordinance. 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 is therefore providing geologic and hydrogeologic services for the project. Specifically, our scope of services for this project will include the following: 10011 Blomberg Street SW, Olympia, WA 98512 1 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 1. Review the available geologic,hydrogeologic, and geotechnical data for the site area. 2. Conduct a geologic reconnaissance of the site area and surrounding vicinity. 3. Investigate shallow subsurface conditions at the site by observing the exposed soil and reviewing published well logs. 4. Evaluate the landslide and erosion hazards at the site per the Mason County Critical Areas Ordinance regulations. 5. Provide 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 erosion control measures. SITE CONDITIONS SURFACE CONDITIONS The proposed building site is located in an area of moderate residential development in the glacial uplands overlooking the Hood Canal. The site has southern exposure. We conducted a reconnaissance of the site area on May 9, 2005. Site elevations range approximately from 400 to 522 feet. A septic system is proposed onsite. The site will be served by a community well. The proposed building location had been previously cleared of vegetation. The site slopes are vegetated with a well- mixed variety of vegetation common to the Northwest. The vegetation includes fir, alder, hemlock, and madrone trees as well as Scot's broom, bracken ferns, sword ferns, manzanita, rhododendron, salal, huckleberry, foxglove, blackberry, and grasses. The only exposed soil is along the access driveway road cuts. At the time of the site visit, we observed no evidence of active surface erosion at or around the proposed building location. Slope instability was not observed near the proposed building location. Active sloughing and raveling was observed along the road cuts. Onsite trees were observed straight and vertical. Surface water flow was not observed at the time of our reconnaissance. Groundwater was not encountered or observed onsite. The groundwater depth was not encountered and is presumed to be deep. The general topography of the site area indicates that drainage is toward the south. 10011 Blomberg Street SW, Olympia,WA 98512 2 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SITE GEOLOGY The site is generally situated within the Puget Sound glacial upland. The existing topography, as well as the surficial and shallow subsurface soils in the area, are the result of the most recent Vashon stale(stage)of the Fraser glaciation that occurred between about 10,000 and 12,000 years ago, and weathering and erosion that has occurred since. A description of the surficial soils is included in the "Site Soils" section of this report. In general, the soils are composed of glacial material. SITE SOILS The Soil Survey of Mason County, USDA Soil Conservation Service (1960)has mapped the site soils as Hoodsport stony sandy loam, 5 to 15 percent slopes(Hg). The survey reads: This soil differs from Hoodsport gravelly sandy loam, S to 15 percent slopes, in having many large, irregular stones and boulders scattered over the surface and in the soil and parent material. This lessens the desirability of this soil for any use. ram- f 7? r The Geologic Map of Washington — Northwest Quadrant (2002) has mapped the site geology as glacial till 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 r- Vashon Drift undivided. 10011 Blomberg Street SW, Olympia,WA 98512 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY � �� 5 ..`tea .•� .:.y�; :..aS:•s.. A f+ The Geologic Map of North Central Mason County, Washington (1976) by Carson has mapped the site as Lodgement till (Vlt). Lodgement till is described as, "compact boulder to clay (generally overlain by 0.5 — 1.5m ablation till." SUBSURFACE EXPLORATIONS Subsurface conditions at the site were evaluated by observing the exposed building site soil and reviewing available well logs. Depth to competent soil is approximately 6 inches throughout the proposed building location. Static groundwater is presumed deep and beyond the scope of this project. t�d 10011 Blomberg Street SW, Olympia,WA 98512 4 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY SUBSURFACE CONDITIONS In general, undisturbed dense Hoodsport gravelly sandy loam was observed throughout the proposed building location. Groundwater seepage was not observed onsite. Based on the site topography and the nature of the near surface soil, seasonally perched groundwater conditions are not expected during periods of extended wet weather. i SLOPE STABILITY Slopes in excess of 100 percent were observed onsite. Since slopes of 40 percent or greater with 10 feet or more of vertical �� i us o � Q relief occur on portions of the site, Mason County requires that BM' a geotechnical report be completed according to the Critical ���` �f9 Areas Ordinance. v� ' r 1 (r UM The near-surface soils are in a dense to very dense condition Ayock Pt except at the ground surface. The surficial soils are generally in S M s a medium dense condition. In general, the undisturbed native soils of the site consist of a i �'•? mixture of variable amounts of sand, silt,and gravel. These soil materials are in a dense condition except where they have been disturbed by weathering activity. These soils are generally / Ufa stable relative to deep-seated failure. Sloughing, undercutting, and active erosion were observed along the road cuts. Urs Urb Weathering, erosion, and the resultant sloughing and shallow sGk 1:24,000 landsliding are natural processes that can affect steep slope r areas. Instability of this nature is typically confined to the upper weathered or disturbed zone,which has been disturbed and has a ,_' _ lower strength. No surface water or active erosion was observed at the proposed building location. 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. Erosion in steep slope areas such as this can be reduced by encouraging vegetation and discouraging runoff from the steep slope. Erosion control recommendations for the sloping areas are provided in the"Erosion Control'section of this report. 10011 Blomberg Street SW, Olympia,WA 98512 5 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Yr Y r 1 l 4� K 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 building location slopes are stable relative to deep- seated instability and will not be affected by the proposed structure if our recommendations are respected. The proposed structure will not undermine adjacent structures. 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 minimized in such a manner as to prevent harm to property and public health and safety, and the project will cause no significant environmental impact. In general, the Hoodsport soils observed at the site may be suitable for use as structural fill material. 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 spread footings may be utilized at the site for support of the structure. We do recommend that roof and footing drains be installed for the structure with conventional spread footings. A vapor barrier is recommended for all slab-on-grades. Pertinent conclusions and geotechnical recommendations regarding the design and construction of the proposed single-family residence are presented below. LANDSLIDE—EROSION HAZARD AREAS CLASSIFICATION The Mason County Critical Areas Ordinance (17.01.100) defines a landslide hazard area as one containing slopes equal to or greater than 40 percent with more than a 10-foot vertical relief The southeastern slope is in excess of 40 percent and the vertical relief is in excess of 10 feet. Based on this, this site does meet the technical criteria of a landslide hazard. The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977) describes the southern site area as Class 3. Class 3 is described as: 10011 Blomberg Street SW, Olympia,WA 98512 6 Phone 4: (360) 754-4612 Fax 4: (360) 7544848 GEOTECHNICAL TESTING LABORATORY Areas inferred to be unstable because slopes, generally greater than 15 percent, are underlain by weak, unstable materials in which old or recently active landslides have occurred. Includes areas of sand and gravel on top of impermeable silt and clay, mostly along steep valley sides. The Mason County Critical Areas Ordinance(17.01.104)defines an erosion hazard area as: 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 ("Ae"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 Hoodsport gravelly sandy loam (Hg). This site does not meet the technical criteria of an erosion hazard area. SLOPE STABILITY Based on our field observations, explorations and our experience with the soil types encountered on the property,we conclude that although portions of the slopes on the lot exceed 100 percent, the site is generally stable relative to deep-seated failure in their present configuration. The Coastal Zone Atlas, Volume 9, Mason County (MA-3) maps the site as Vashon glacial till (Q„t). The till is a tough, dense material of low permeability. It provides excellent foundation support. The site slope stability is described as "unstable"at the building site. To prevent minor sliding, uncompacted fill material and any underlying vegetation shall be removed in order to construct the foundation. 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. As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural processes that affect slope areas. 10011 Blomberg Street SW, Olympia,WA 98512 7 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY 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 destabilizing 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. BUILDING SETBACK A building setback from landslide hazard areas is required unless evaluated and reduced by an engineering geologist or a licensed professional engineer. Based on our geotechnical evaluation of the site and our experience in the area, a building setback will be needed for this lot. A building setback of 30-feet from the crest of the (30% or more) slope to the bottom of the footing should Setback otherwise be observed. The building setback may be measured from the bottom of the footing to the face of the steep slope in accordance with the 2003 International Building Code (IBC). Peak Shear Stress vs. Normal Stress Sandy Loam 3000 — 42 2500 c a 2000 N N N 1500 W N t co Y a� 1000 Q. 500 1—�1/4 ton �1/2ton 0 * 1 ton 0 5W 1000 150n 2000 25Oi 0 3000 Normal Stress(psf 10011 Blomberg Street SW, Olympia,WA 98512 8 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Slope stability was modeled using the GEO-SLOPE/W program (version 5.20) in both static and extreme dynamic conditions (ca = 0.3). Factors of safety were determined using Straight Site -- Slope A Bishops, Janbu, and the Analysis Method: Morgenstern-Price Morgenstern-Price methods. The Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vertical glacial till was determined to have a unit weight of 131 pcf, cohesion of 200 psf, and a shear angle (�) of 42°. Under static conditions, the slopes were stable to shallow failure. Under . . •• dynamic loading, the 3328 computations demonstrated that the •••,i" P �• / , slope is not susceptible to surficial ��'.•. .,.�'. •• com raveling or deep-seated failure. The �' ' ••••••- following figure illustrates the moment factor of safety for slope "A" 540 •1• under the existing conditions. The 520 figure is the solution of greatest S 500 concern and exhibits the need fora o 480 HoadsP«< building setback of 30-feet from the ; 460 unk Weight.131 � co 440 Cohesion:_00 crest (30%or more)of the slope. w Phi:as 420 400 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Distance(ft) As previously discussed, weathering, erosion and the resultant surficial sloughing and shallow landsliding are natural processes that affect slope areas. Surficial raveling and sloughing was observed onsite along the oversteepened roadside cut. To manage and reduce the potential for these natural processes, we recommend the following: 1. No drainage of concentrated surface water or significant sheet flow onto the sloped areas. 2. No filling within the setback zone unless retained by retaining walls or constructed as an engineered fill. 3. Trees may be removed on sloped(30%or more)areas as long as the stumps remain. ijou _ 4 - r � fz• 10011 Blomberg Street SW, Olympia,WA 98512 9 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY SEISNIIC—LIQUEFACTION HAZARD According to the Seismic Zone Map of the United States contained in the 2003 International Building Code (IBC), the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g). 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 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 C to D. Site class C is a very stiff soil or soft rock and site class D is a stiff soil. 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, as defined by Table 1615.1.1 (IBC). This is based on the range of SPT (Standard Penetration Test) blow counts and/or probing with a %-inch diameter steel probe rod. The shallow soil conditions were assumed to be representative for the site conditions beyond the depths explored. Based on our review of the subsurface conditions, we conclude that the site soils are only mildly susceptible to liquefaction. The near-surface soils are generally in a dense condition and the static water table is located well below the surface. 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. EROSION CONTROL 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 and limited to the active construction areas. Yard landscaping around the home is permissible,but understory growth on the slopes should be encouraged as much as possible as a deterrent to erosion. Trees located on steep slopes may be removed only if the stumps remain to deter erosion. Temporary and permanent erosion control measures should be installed and maintained during construction 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. A typical silt fence detail is included on Figure 2. Any re-contouring of the site will create a need for erosion control measures as listed above. EARTHWORK 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 stripping on the order of 6 to 12 inches will be necessary to remove the root zone and surficial soils containing organics. Areas with deeper, unsuitable organics should be expected in the vicinity of depressions or heavy vegetation. Stripping depths of up to 18 inches may occur in these areas. These materials may be stockpiled and later used for erosion control and landscaping. Materials that cannot be used for landscaping or erosion control should be removed from the project site. 10011 Blomberg Street SW, Olympia,WA 98512 10 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 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. We recommend that trees be removed with the roots, unless located on a slope. Excavations for tree stump removal in any building area should be backfilled with structural fill, compacted to the density requirements described in the "Structural Fill"section of this report. 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. 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 90 percent of MDD (maximum dry density as determined in accordance with ASTM D-1557) to within 2 feet of subgrade and 95 percent MDD in the upper 2 feet. 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 5 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. 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. G i 1x * y 10011 Blomberg Street SW, Olympia,WA 98512 11 Phone#: (360) 7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY SUITABILITY OF ONSITE Sons AS FILL Onsite soils may be considered for use as structural fill. In general, the native soils (sand, loam, 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. 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 will likely 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. Flatter cut slopes will be necessary where significant raveling or seepage occurs. Surface drainage shall be directed away from all slope faces. All slopes should be seeded as soon as practical to facilitate the development of a protective vegetative cover or otherwise protected. FOUNDATION SUPPORT Where foundation elements are located near slopes of 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 footings and continuous wall footings to meet IBC. 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. 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 0.40 be used to calculate friction between the concrete and the underlying soil. Passive 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 inch or less. Most of the settlements should occur essentially as loads are being applied. However, disturbance of the foundation sub-grade during construction could result in larger settlements than predicted. 10011 Blomberg Street SW, Olympia,WA 98512 12 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 minimum 6- inch thickness of coarse sand and/or gravel containing less than 3 percent fines (by weight). The drainage material should be placed in one lift and compacted to an unyielding condition. A synthetic vapor barrier may 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. RETAINING WALLS Retaining walls may be utilized on the sloping portion of the site to retain fill material. The lateral pressures acting on the subgrade and retaining walls will depend upon the nature and density of the soil behind the wall. It is also dependent upon the presence or absence of hydrostatic pressure. If the adjacent exterior wall space is backfilled with clean granular, well-drained soil (washed rock), the design active pressure may be taken as 0.40 (coefficient). This design value assumes a level backslope and drained conditions as described below. Retaining walls located on or near the toe of a slope that extends up behind the wall should be designed for a lateral pressure, which includes the surcharge effects of the steep slope in proximity to the wall. Although not expected at this site,the following data is provided for planning purposes. For an irregular or composite slope,the equivalent slope angle may be determined by extending a line upward from the toe of the wall at an angle of 1 to 1 (Horizontal to Vertical) to a point where the line intersects the ground surface. The surcharge effects may be modeled by increasing the equivalent fluid pressure for flat ground by the percentage given in the following table: SLOPE INCLINATION: EQUIVALENT FLUID PRESSURE Slope Angle Percent Increase Equivalent Fluid Pressure Horizontal 0% 35 pcf 3H:1V 25% 44 pcf 2H:1 V 50% 53 pcf 1H:1V 75% 61 pcf If the walls are greater than 4 feet in height, exclusive of the footing, additional design considerations should be applied. Positive drainage, which controls the development of hydrostatic pressure, can be accomplished by placing a zone of coarse sand and gravel behind the walls. The granular drainage material should contain less than 5 percent fines. The drainage zone should extend horizontally at least 18 inches from the back of the wall. The drainage zone should also extend from the base of the wall to within 1 foot of the top of the wall. The drainage zone should be compacted to approximately 90 percent of the MDD. Over compaction should be avoided as this can lead to excessive lateral pressures. A perforated PVC pipe with a minimum diameter of 4 inches should be placed in the drainage zone along the base of the wall to direct accumulated water to an appropriate discharge location. 10011 Blomberg Street SW, Olympia,WA 98512 13 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY We recommend that a non-woven geotextile filter fabric be placed between the drainage material and the remaining wall backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage zone can, with time, reduce the permeability of the granular material. The filter fabric should be placed in such a way that it fully separates the drainage material and the backfill, and should be extended over the top of the drainage zone. Lateral loads may be resisted by friction on the bases of footings and as passive pressure on the sides of footings and the buried portions of the wall. We recommend that an allowable coefficient of friction of 0.40 be used to calculate friction between the concrete and the underlying soil. RETAINING WALL ALTERNATIVES Typically, block wall systems are more cost effective for long-term walls than the other options. Specific design criteria for these options can be provided at your request by the block manufacturers. SITE DRAINAGE All ground surfaces, pavements, and sidewalks should be sloped away from the residence and associated structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight-lined to an appropriate infiltration area. We recommend that conventional roof drains be installed. Footing drains shall be installed for the single-family residence. 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. We recommend that the collected stormwater runoff be directed, if possible, to the western portion of the site by tight-line. Drainage control measures are included on Figure 3. Onsite irrigation to lawn areas should be closely monitored. We do not expect any adverse affects on the recharge condition of the groundwater system. A, n.P 10011 Blomberg Street SW, Olympia,WA 98512 14 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY LIMITATIONS We have prepared this report for Mike Straight and members of his design team, to use in the design of a portion of this project. The data used in preparing this report, and this report, should be provided to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and interpretations are based on data from others and our site reconnaissance, and should not be construed as a warranty of the subsurface conditions. This report is quantified as a micro-study and not a macro-study. Geotechnical Testing Laboratory and its personnel cannot be responsible for unforeseen and widespread geologic events (such as earthquakes, large-scale faulting, and mass wasting)beyond the scope of this project. Variations in subsurface conditions are possible and may occur with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient consultation with our firm during construction should continue, to confirm that the conditions encountered are consistent with those indicated by our observations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated,and to evaluate whether earthwork and foundation installation activities comply with our specifications. If our analysis and recommendations are followed, we do not anticipate any onsite or offsite impact from the proposed construction. It is our conclusion that potential landslide hazards can be overcome so as not to cause harm to property,public health and safety, or the environment. The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. If there are any changes in the loads, grades, locations, configurations or types of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. C� Was Respectfully submitted, e �� r GEOTECHNICAL TESTING LABORATORY 07 Harold Parks, L.G., L.E.G. 827 O�°� Senior Engineering Geologist aad Go HAROLD PARKS 10011 Blomberg Street SW, Olympia,WA 98512 15 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Vicinity Map 0�Ti I f` f' 63 Point T-_�� " (j(FtLoke\\ � '1Zl' l •-;�' SO T — t lyi _will f o rfL_ Xt. q fr \ { - t ' _ j0'be,. ��. ( / �•� f I��j/ e J 0..�� 7- 4 1 1 s•f —11 fs �� , Fi gure 1 10011 Blomberg Street SW,Olympia,WA 98512 Phone#: (360) 754-4612 Fax#: (360) 754-4848 FILTER FABRIC MATERIAL W WIDE ROLLS A UABRIC'LESORWREPoNGTOAI AO Geotechnical FABRIC TO WIRE ABRIC4 GAUGE WIRE FABRIC OR EOUVAUBJT 150' 7.� Testing Laboratory 7-C N nO h O ACC S RO,a � BURY BETTER OR EOUSAL ALTERNATE MATERIAL IN M17 FILTER O//�� TR@KH (0 STEEL FENCE POSTS FILTER FABRIC 8' P O S E D 7X2'X14 GA`1GE WIRE O �� FABRIC OR EQUIVALENT GROU EPTIC 2 7 GROUND SURFACE 5-O' LOCATION B �L t, PROVIDE NAVELSA (FILL WA°J® GRAVEL BOTH SIDES IN OF FILTER 1Y AND ON BOTH SDESOF FILLER ---- ------- FENCE FABRIC ON THE SURFACE 8'M 7X4'WOOOPOSTS ALT.STEEL FENCE POSTS Geotechnical Services -- FlLTFN FABPoO FBlCE N07� --- 1.FILTER FABRIC SHALL BE PURCHASED IN ACONRMXAISROLLCUTTO QA/QC Services THE LENGTH OF THE BARRIER TO AVOIDUSE OF JOINTS.W-EN JOINTS Testing Services _-- - ARE NECESSARY,FILTER CLOTH SHALL BE SPUCEDTOCeET ER ONLY AT 10 FASTENED AT B T WITH A TO THE P ST. OVERLAP AND SECURELY -- ` "-" FASTENED AT BOTH ENDS TO THE POSE. 1 l D 2.POSTS SHALL BE SPACED A MAMMUM OF B FEET APART MA DRIVEN SECURELY INTO THE GROUND(MINIMUM OF 301NC/E51. POTENTIAL - -- -� '� '� 3 A TRENCH SHALL BEEXCAVATEDAFPROAMATELY8INCHESWICE AND 12 10011 Blomberg St.SW INFILTRATION INCHES DEEP ALONG THE UNEOF POSTS*0UPSLOPE FROM THE BA;MER. Olympia WA 98512 N.� 4 WHENSTANDARD STRENGTH FILTER FABRIC MUSED,AWIRE MEW '7 ---- --LOCATION- - SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE Phone:(360)754-4612 OF THE POSTS USING HEAVY-DUTY WIRE STARES AT LEAST 1 INCH LONG,TIE WIRES OR HOG RINGS.THE WIRE SHALL EXTEDINTO THE PBX:(360)754-4848 --- - M -_ TRENCH A MINIMUM OF 41NCHE5 MID SHALL NOTDOEO _-, --_ _ INCHES ABOVE THE ORIGINAL.GROUND SXRFACE. T 5.THE STANDARD STRENGTH FILTER FABRIC SHALL BE STPRSJ OR WIRED Date: 05/13QW5 VA �} TO THE FENCE AND 20 INCHES OF FABRIC SHWIBEEMEdED Designed by: LL M __________________� _ NICE •��I INTOTHETRENCH.THE FABRIC SHALL NOT EMBRD MORE THAN 35 00 - - ------ t.Y' INCHES ABOVE THE ORIGINAL GROUND SURFACE FILTER FABRIC SHALL HOT BE STAPLED TO THE ENSONG TRIES. Drawn by: LL ------------------------ -- 00 �L ________--- _- N B.WHEN EXTRASTRENGTH FILTER FABRIC AND CLOSER POST SPAONG IS Checked by: LL - A CASE THE IFRILETER FSUPPORT IC IS STA FENCE WI MAP�DIREECT�LY TORHE DV9g#:05-13-05-042 SOO POSTS WITH ALL OTHER PROVISIONS OR ABOVE NOTES APPLYING 7.FILTER FABRIC FENCES SHALL NOT BE REMOV®BEFORE THE LPSLOPE __________________________ ___-__ AREA HAS BEEN PERMANENTLYSTABILIZED _____________________ 8.RAINFFILTERALL LL BRICAND FENCES SMALL BE DURING CTED RAIN ALL ER ANY -'- ---- RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL.ANY ----------------------------------------- REOURED REPAIRS SHALL ff MADE IMMEDIATELY. --------------------------- '--- GENEML l31Ot10N CONTROL NOTE: 49UEROSION CONTROL MEASURES SHALL BE BR PLACE PRIOR TO THE .7 BEGINNING OFCONSTRUCTION.THE FROECr ENGB�R MATTECOLNTY SHALL INSPECT AND APPROVE THE INSTALLATION OF EROSION CONTROL MEASURES PRI OR TO BEGBNNG CONSTRUCTION ______________ ____________ TEDTO 2.EROSION CONT TH CONTRMEASUAES CTOR'S NOT UMSIBLEF R ITEMS IN THISPLAN.AND MOUNTAI NANO IOF ALLE OSON CONTROL INSTALLATION AND STING AACOOF N1670SONCONTROLMEASURES -- --------------------- ------------ --' NO SILTATION OF EXISTING OR PROPOSED DRAINAGE FACILIRES PROJECT NAME: - -- ____ NORTH OF BE O OFF CARE SHALL BE TA TO PREYEd MGRATO R -_.-________________________________ ____________ OF SILTS TO OFF SITE PROPERTIES ------ . --- MIKE STRAIGHT ------------------------ ---- ------------ SCALE 1"=50 3.THE CONTRACTOR SHALL MARE DAILY NECESSARY RE AJ ALL SORA T1 .-- - --- TO THE EROSIONCSANDMMHE ANY ASURES THECOYRBNRSORADpTONS 345 SHAR LANE NORTH - ---------------- C.I.=7 TO THE EROSION CONTROL MEASURES.TIE UJNIRACTOR$HALL PROMOS -- ____-_-_- _---------------------------- -- _-_-'- ADDITIONAL EROSION CONTROL MEASURES ASDEIERMNEDNECESSARf LILLIWAUP, WASHINGTON ------------- ------ ------------- ------------- --- DATUM ASSUMED BY THE COUNTY INSPECTOR ANUORTIEPROECTBRGREER FAILURE ----------------- -- - WIT 6----------- ------------- --- THIS IS NOT A SURVEY TO REQUIREMENTS NTS ALL ESULINDSUTEEROSON CONTROL ____________ ___ REOUIREMENTSMTR CONTRACTOR MAYOR PROIELTESBBNG LEVIED PARCEL 323093400030 AGAINST THE CONTRACTOR ATOVR PROWL-Cf OWNER ING THE WET SEASON _____-___ ____ 0 10 20 30 40 50 4 SHRALL BE STABILIZED`MTHINO48 HO�URSTAFTER STOP EROSION pVReLNLNL� /' ------ -- _-_--___-_--- CONTROL MEASURES SHALLINCUDEELTNOTBEUMITEDTO, RV�I�IL71 W i CO / -- - a-�T- -- ---- COVERING THE NG,STAWMATING.JIJTG MATTING, STRAW , 1 I I / I % •JV,------ PLASTIC SHEETING,STRAW MATTNG,.MEMATi1NG,STRAW MULCH, ORWOODCHIPS.SEEDING OF THE DISTURBED AREAS STALL THE PLACE AS WEATVER PERMITS T Cf.�Si11 R/O 1 R 5.ALL SEEDED RE EGEr AREAS SHALL BE CHECKEDOMUETE REGULARLY/ T O MARCH)ALL DISTURBED SOILS I I i.} TO MAKE SURE VEGETATIVE COVERAGE ISCOALEIE.AREAS SHNI BE ______- / 1 1 VM REPAIRED,RESEEDED.MID iEt1Il1ffi7 ASREOURED _______________ _ / 1 1 \o -__ ____________ _ / 1 1 --__ -------- --------- / / C— 8.TRACIONG OF SOIL OFFSITE WILL NOT BE NlOVAD.IF MA'SULIS w� - END ____ __ ____ _________________ ,,^^ TRACKED ONTO ACOUNTY STREET,IT9A1ff REMOVED BY THE _ W / OF TNAT WORgNG DAY.ANY FURTHER TRIlTOIJG OF MLA WILLTF81 _______ __-__. BE PREVENTED BY SWEEPING OR WASHING OFTf VEHIClESTRES BEFORE DRIVING ON ACOIMIY STREET. 7.NO MORE THAN 500 LF OF TRENCH ON A DOWNSLOPE OF MORE THAN PERCENT SHALL BE OPENED AT ONE TIME, 8.EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SIDE OF TRENCHES. 9.TRENCH DEWATERING DEVICES SHALL BE DISCHARGED IN A MANNER THAT V LL NOT ADVERSELY AFFECT FLOWING STREAMS.DRAIN AGE SYSTEASOR OFFSITE PROPERTIES. SCALE:1 IrO C 50 led 10.ALL STORM SEWER INLETS RECEIVING RUNOFF FROM THE PROJECT WRING CONSTRUCTION SHALL N W LL BE FILTERED BEFORE PROTECTED ENTERING WATER GTE CONVEYANCE SYSTEM. N OI 11 ALL OFF.SITE CATCH SHALL BE PROTECTEDAFROMSTAnON THE ADJACENT TO T 9TE N 12 ALL DI STU AREAS SHALL BE SEEDED OR SODDED UPON COMPLETION OFWORKRTTHE CONTRACTOR SHALL RESPONSIBLE TOENSLNETHAT FIGURE 2 COMPLETE COVERAGE OF THE DISTURBED AREAS ISPROMDED&THAT GROWTH OF THE VEGETATION DIME ED. SITE PLAN 13.CATCH BASINS SHALL TRAPSEDIMENTNT OR OR FILTER FAStlC MUSE� PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED. .1 if a ' - i• IS ism gd t/ 1 MP 1 1 if � rY �{N, r��t �' > 2�S�k�� 3 1 © � • �aF d `" -�' �' ,r .- s •�• J► Lfir it+► 2 ,N f�4 �Fa�E 4 Jam,. ''� co. M1� ` ��'. Ln `T"'T'.'..0oiw �. w �� •r�` .�.� - Qd' � -f �"l �.� ��" y9 1 ice, ti e, ow $80 r M1 t J 1y ti'0 Il S 11M ro of � A Q o � � •�'`�' lf � 340 p a ° 3 bti tf 37.0 3°0 N 4 A � AO N MAPLE LN R, 000 �O o 16 /" HOOD CANAL a0 V �G -G C� C • r Lam. 120 o _ oN o _ N o0 G - 0 *tom e N�SHAR' � N ' S M O Z �^ A : ' 6 LL) av&- 00r 9 GEOTECHNICAL TESTING LABORATORY MIKE STRAIGHT 1EIV ED P.O. Box 149 LILLIWAUP, WA 98555 JUN Z 2 2006 pQpA�p�n RE: DAMAGE ASSESSMENT SITE: 345 SHAR LANE NORTH U III[0## LILLIWAUP, WA 98555 �''B�OC�y04 GPS LOCATION: N47029.670' W123004.514' PARCEL NUMBER: 323093400030 DATE: 06/9/2006 Mr. Straight: As requested, we have conducted a follow up site visit to determine if conditions have changed since May 2005. We are pleased to report that the site conditions are identical to the conditions observed in May 2005. The recent trenching of utilities along the access road is essential to the multiple parcels served by Shar Lane. Dry raveling of the cut slopes adjacent to Shar Lane is common for well-rounded and unconsolidated glacial drift. Along Shar Lane, vegetation limits are similar to earlier conditions and only minor erosion was observed. After utility construction, no further trenching is anticipated; a roadside ditch will control stormwater. The proposed building location remains undisturbed and ready for construction. No impact has occurred to the southern slope. We determine that conditions remain consistent to the conditions previously observed and reported in our geotechnical report. 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. Respectfully Submitted, GEOTECHNICAL TESTING LABORATORY Harold Parks, L.E.G., L.G. Senior Engineering Geologist 10011 Blomberg Street SW. Olympia, WA 98512 1 Phone#: (360) 754-4612 Fax#: (360) 754-4848 . •s �' STA7- q, MASON COUNTY oP s° PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER z ° v p Shelton, Washington 98584 J y pJ a0 1%4 DATE: June 8, 2006 INTER-DEPARTMENTAL COMMUNICATIONS TO: Tammi Clark PARCEL # 32309-34-00030 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-00679 SUBJECT: Geo-Tech Report Review Hold NAME: Straight Mike Tammi, The Geotechnical Report prepared for the proposed new single-family residence and shop located at 345 North Shar Lane near Lilliwaup is still under review by Public Works. On June 7, 2006 1 had written a report stating that the May 23, 2005 Geotechnical Report would be acceptable if the author of that report certified that the report can still be used in lieu of a new Geotechnical Report. Today I am asking for a re-evaluation of that report and any new recommendations. Today I was in the area and visited the site. I noticed that underground utilities were being run up Shar Lane North. The utilities were being placed in the shoulder of that access road coming up the hill and were being dug into the cut that is below the property discussed in this report. Walking the road to the west I noticed some erosion on the bank down the road at a switchback. A neighbor had mentioned a homeowner on a lot above that switchback had some ground movement on that lot. She did not say where or what kind, erosion, sluffing, etc. I also went up to the site and noticed stakes for the proposed shop. The set back for the proposed shop looked good. My concern is the future home set back and is it going to be placed where your first Geotechnical Report expects? A drawing I received today from planning dated May 9, 2005 has the home placed more west. I know that geology does not change over night. I am requesting that The Geotechnical Report be re- evaluated to look at: 1 . Slope stability for static and seismic due to work on the access road below the site. This was excavating three feet down in the toe of the cut bank around elevation 450. 2. Are new setbacks required? 3. Physically will the structures fit with the set backs required? 4. Check the area once again for geological feature changes. 5. Any changes in recommendations and conclusions. The Geotechnical Report Review is on hold and no further action will be taken by Public Works until we receive what is requested above. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. S,I;nrely'nSliva ograms Engineer GRAVEL ACCESS ROAD 60'EASEMENT WATER LINE _ ` — o SOIL LOGS I S w�A p, PRIMARY&RESERVE - - . DRAINFIELD AREA _ - - - - J Gad �`�� 13 TRANSPORT LINE UBLE ENCASED D AN IV OF WATER) 3 BDRM HOME SEPTIC♦PUI/P TAMM I 50'SETBACK f� 44'1'I!1%a FROM TOP OF BANK Q �Of T !. BUT PE A,"J- WITH ROOTS TOP OF BANK TO BOTTOM 1 LS APPROVED, o sow G ^, ® sOM�a>tr�„vF MASON' COUNTY DCD PLANNI G L& U euT P� t SITE PLAN REQUIRED TO BE ON SITE VftITHI�OTB CHANGES SUBJECT TO APPROVAL — — TO BOTTOM 3y - - DateGRAVEL ACCESS ROAD 60'EASEMENT yt Ya 3 Zi 7 ?' SITE PLAN: FOR: STRAIGHT JOB#: PARCEL#: 32309-34-00030 DATE: 09 MAY 2005 BY: TJS DESIGN PAGE OF NORTH ARROW: SCALE: 1"=6' • 0 � 12' °N.STpTFo� MASON COUNTY �o � PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER ° s N = Shelton, Washington 98584 N y bj Z y 1%4 DATE: June 26, 2006 INTER-DEPARTMENTAL COMMUNICATIONS TO: Tammi Clark PARCEL # 32309-34-00030 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-00679 SUBJECT: Geo-Tech Report and Addendum Review NAME: Straight Mike Tammi, The Geotechnical Report and addendum to Geotechnical Report dated June 9, 2006 prepared for the proposed new single-family residence and shop located at 345 North Shar Lane near Lilliwaup has been received and reviewed by Public Works. On June 8, 2006 1 had requested an update to the May 23, 2005 Geotechnical Report along with a visit to the site to see if site conditions had changed since the May Report. The author of the addendum wrote that they are pleased to report that site conditions are identical to the conditions observed in May 2005 after visiting the site. They determined that conditions remain consistent to the conditions previously observed and reported in their geotechnical report. The May 23, 2005 report appears to satisfactorily address County requirements for Geotechnical Reporting. The report's author indicates that in their opinion that the site is suitable for the proposed project. The author goes on to say that if their analysis and recommendations are followed, they do not anticipate any onsite or offsite impact from the proposed construction. Slope stability was modeled in both static and extreme dynamic conditions. A building setback of 30 feet from the crest of the 30% or more slope to the bottom of the footing should be observed per the report. Based on the contents of the addendum and the May 2005 geotechnical report, I recommend accepting the report as satisfying the County's requirements for stability investigation and geotechnical reporting. Recommendations and Comments contained in the report should be incorporated into the site development plans and made conditions for permit issuance. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. ;Si,n rely, John Sliva ograms Engineer 00 c —7 9 GEOTECHNICAL TESTING LABORATORY MIKE STRAIGHT F?ECIWE P.O. Box 149 LILLIWAUP,WA 98555 f(�f�Z ? 20�6 RE: DAMAGE ASSESSMENT MASQN�����SITE: 345 SHAR LANE NORTH 1 1 r T I(�.'1k1C 0r K'� LILLIWAUP,WA.98555 w GPS LOCATION: N47029.670' W123004.514' PARCEL NUMBER: 323093400030 DATE: 06/9/2006 Mr. Straight: As requested, we have conducted a follow up site visit to determine if conditions have changed since May 2005. We are pleased to report that the site conditions are identical to the conditions observed in May 2005. The recent trenching of utilities along the access road is essential to the multiple parcels served by Shar Lane. Dry raveling of the cut slopes adjacent to Shar Lane is common for well-rounded and unconsolidated glacial drift. Along Shar Lane, vegetation limits are similar to earlier conditions and only minor erosion was observed. After utility construction,no further trenching is anticipated; a roadside ditch will control stormwater. The proposed building location remains undisturbed and ready for construction. No impact has occurred to the southern slope. We determine that conditions remain consistent to the conditions previously observed and reported in our geotechnical report. 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. Respectfully Submitted, GEOTECHNICAL TESTING LABORATORY A/ai��V "�� Harold Parks,L.E.G., L.G. Senior Engineering Geologist s 0 F 10011 Blomberg Street SW, Olympia, WA 98512 Phone #: (360) 754-4612 Fax #: (360) 754-4848 N ON.STATFp� MASON COUNTY � CcPUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER p S N = Shelton, Washington 98584 �Z N Y Y Epp �O 1W4 DATE: June 8, 2006 INTER-DEPARTMENTAL COMMUNICATIONS TO: Tammi Clark PARCEL # 32309-34-00030 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-00679 SUBJECT: Geo-Tech Report Review Hold NAME: Straight Mike Tammi, The Geotechnical Report prepared for the proposed new single-family residence and shop located at 345 North Shar Lane near Lilliwaup is still under review by Public Works. On June 7, 2006 1 had written a report stating that the May 23, 2005 Geotechnical Report would be acceptable if the author of that report certified that the report can still be used in lieu of a new Geotechnical Report. Today I am asking for a re-evaluation of that report and any new recommendations. Today I was in the area and visited the site. I noticed that underground utilities were being run up Shar Lane North. The utilities were being placed in the shoulder of that access road coming up the hill and were being dug into the cut that is below the property discussed in this report. Walking the road to the west I noticed some erosion on the bank down the road at a switchback. A neighbor had mentioned a homeowner on a lot above that switchback had some ground movement on that lot. She did not say where or what kind, erosion, sluffing, etc. I also went up to the site and noticed stakes for the proposed shop. The set back for the proposed shop looked good. My concern is the future home set back and is it going to be placed where your first Geotechnical Report expects? A drawing I received today from planning dated May 9, 2005 has the home placed more west. know that geology does not change over night. I am requesting that The Geotechnical Report be re- evaluated to look at: 1. Slope stability for static and seismic due to work on the access road below the site. This was excavating three feet down in the toe of the cut bank around elevation 450. 2. Are new setbacks required? 3. Physically will the structures fit with the set backs required? 4. Check the area once again for geological feature changes. 5. Any changes in recommendations and conclusions. The Geotechnical Report Review is on hold and no further action will be taken by Public Works until we receive what is requested above. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Si;John ly�Sliva Programs Engineer t i 1 r Geotechnical Report 345 Shar Lane North Lilliwaup, WA Prepared for: Mike Straight r - i. by {. Geotechnical Testing Laboratory Olympia, Washington May 23, 2005 GEOTECHNICAL TESTING LABORATORY r MIKE STRAIGHT P.O. Box 149 LILLIWAUP, WA 98555 i 1 RE: GEOTECHNICAL REPORT 345 SHAR LANE NORTH LILLIWAUP,WA 98555 t PARCEL 323093400030 N47029.670' W 123°04.514' f' INTRODUCTION This report summarizes the results of our geotechnical consulting services for the proposed single-family residence and shop to be located near Colony Surf,approximately 3.0 miles northeast of Lilliwaup,Washington. The 2.7-acre site is shown relative to the surrounding area on the Vicinity Map,Figure 1. Our understanding of the project is based on our discussions with you and our explorations and review of the site. We understand that the parcel is to be developed with a single-family residence. The site will be accessed by a driveway from Shar Lane off Eagle Creek Road. In general, grading will consist of the excavation of the foundation, footings,and.driveway. 1. , 3 L It The site slopes south from a level area toward the Hood Canal. The steepest slope measured onsite was in excess of 100 percent along roadside cuts. Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Critical Areas Ordinance. 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 is therefore providing geologic and hydrogeologic services for the project. Specifically,our scope of services for this project will include the following: 10011 Blomberg Street SW, Olympia,WA 98512 1 Phone#: (360)754-4612 Fax#: (360) 7544848 i • ' GEOTECHNICAL TESTING LABORATORY 1. Review the available geologic, hydrogeologic, and geotechnical data for the site area. 2. Conduct a geologic reconnaissance of the site area and surrounding vicinity. 3. Investigate shallow subsurface conditions at the site by observing the exposed soil and reviewing published - well logs. 4. Evaluate the landslide and erosion hazards at the site per the Mason County Critical Areas Ordinance regulations. 5. Provide 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 erosion control measures. SITE CONDITIONS SURFACE CONDMONS 1 The proposed building site is located in an area of moderate residential development in the glacial uplands overlooking the Hood Canal. The site has southern exposure. We conducted a reconnaissance of the site area on May 9, 2005. Site elevations range approximately from 400 to 522 feet. A septic system is proposed onsite. The j site will be served by a community well. i S a I The proposed building location had been previously cleared of vegetation. The site slopes are vegetated with a well- mixed variety of vegetation common to the Northwest. The vegetation includes fir, alder, hemlock, and madrone f trees as well as Scot's broom, bracken ferns, sword ferns, manzanita, rhododendron, salal, huckleberry, foxglove, blackberry,and grasses. The only exposed soil is along the access driveway road cuts. At the time of the site visit, we observed no evidence of active surface erosion at or around the proposed building location. Slope instability was not observed near the proposed building location. Active sloughing and raveling was observed along the road cuts. Onsite trees were observed straight and vertical. Surface water flow was not observed at the time of our reconnaissance. Groundwater was not encountered or observed onsite. The groundwater depth was not encountered and is presumed to be deep. The general topography of the site area indicates that drainage is toward the south. 10011 Blomberg Street SW, Olympia, WA 98512 2 Phone#: (360) 7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY j STfE GEOLOGY i The site is generally situated within the Puget Sound glacial upland. The existing topography, as well as the surficial and shallow subsurface soils in the area, are the result of the most recent Vashon stade(stage)of the Fraser glaciation that occurred between about 10,000 and 12,000 years ago, and weathering and erosion that has occurred since. A description of the surficial soils is included in the "Site Soils" section of this report. In general, the soils are composed of glacial material. SITE SOILS The Soil Survey of Mason County, USDA Soil Conservation Service (1960)has mapped the site soils as Hoodsport stony sandy loam, 5 to 15 percent slopes(Hg). The survey reads: £ This soil differs from Hoodsport gravelly sandy loam, 5 to 15 percent slopes, in having many ` large, irregular stones and boulders scattered over the surface and in the soil and parent material. This lessens the desirability of this soil for any use. t 'a r The Geologic Map of Washington — Northwest Quadrant (2002) has mapped the site geology as glacial till deposits (Qgt) of continental glacial origin. The report reads: Till — Unsorted, unstranfred, 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. 10011 Blomberg Street SW, Olympia,WA 98512 3 Phone#: (360)754-4612 Fax#: (360) 754-4848 Y �••�i •5�'e �Q.�tr .�,; �.'ama.'t''`y/ w;.',,,„„ •av � �' �- r .raw �d� F r. J •f � •� ` t �peMW'a4 I Y1 y�''.ar �K� �^� .. t:. •.nl •.� �`+►tw•ar..cn.. ::^ .a ..�'..a'"vr.S�. t!r `'.'a 1'' ,��' ;A, '� �p;�. .� :' • a ^yJW '��*.A'- � x'� -� a'• � a"Ib A� � •c*W y�..aa..-.'__r +ra'+`a,t=G 't,\ .. �wAc.q f .�i •.. �" ,+,jy '� �,a� WS. •1,.,,e � �a g ;,�` � 6� �' �E.��•."^'� � to.�III* ��v..,�+'�. �E���: t��a .,;ti�'!>`}sr,�..a� «ilp,;. �" �L'�'.{ r'" � ..a"ar ,�,• a 1h,. .h•.- _ .`$'� y, n f, '�' f+S °'«,,,, �' ,;�•'�. _ ,s.. � " ,fir,�i`:s�+, �.„m �,\ :xe:A- _ap` �^ '�. µ,�8a•$;-Fl fit l� ' ki -25 low um AI �i ~•1 �'� ''� � �� 4 ,:«v Irk Y# aa' d.rw. .a yl s.� °liR°� i _^ _ € y •Ys'e}J s. �'+ .�.._ i, x' '•ya_.,( 7,4 'I /• I/ I I I / / / I • / • • • •1 •1:1 •\';,')w ^a�'6 �3 +you • - rr' ^��, 'y'� 1 u r •r -- ^%�`, + ..e�'k� �. \ .<r-} j'<�'�;'"Tr f t ... '°��:,� "� a.ati� • s1 � ,� E a ��2Y a •� '�,.� •�'Yst d. ' .�,� '" ` s�y_. ''y. "`�`t ! y.Sig �t.,. a.,�! .J } "+F• GEOTECHNICAL TESTING LABORATORY SUBSURFACE CONDMONS In general, undisturbed dense Hoodsport gravelly sandy loam was observed throughout the proposed building location. Groundwater seepage was not observed onsite. Based on the site topography and the nature of the near surface soil, seasonally perched groundwater conditions are not expected during periods of extended wet weather. c y i ,a'{r ti SLOPE STABIL ry Slopes in excess of 100 percent were observed onsite. Since / ,. i slopes of 40 percent or greater with 10 feet or more of vertical "n relief occur on portions of the site, Mason County requires that a M a geotechnical report be completed according to the Critical .4— Un Areas Ordinance. 4- �r1 ( � Urs The near-surface soils are in a dense to very dense condition , ��� Ayock Pt except at the ground surface. The surficial soils are generally in ; e M 8 I . a medium dense condition. ; i i " In general, the undisturbed native soils of the site consist of a j mixture of variable amounts of sand, silt,and gravel. These soil materials are in a dense condition except where they have been f disturbed by weathering activity. These soils are generally[ un stable relative to deep-seated failure. Sloughing, undercutting, rG`•. and active erosion were observed along the road cuts. i urs uM Weathering, erosion, and the resultant sloughing and shallow scale1:z..wo • 3 1 Ylb i�. ' landsliding are natural processes that can affect steep slope l " "`` M0 t"o Maa areas. Instability of this nature is typically confined to the upper weathered or disturbed zone,which has been disturbed and has a 6 lower strength. No surface water or active erosion was observed at the proposed building location. 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. Erosion in steep slope areas such as this can be reduced by encouraging vegetation and discouraging runoff from the steep slope. Erosion control recommendations for the sloping areas are provided in the "Erosion Control'section of this report. 10011 Blomberg Street SW, Olympia,WA 98512 5 Phone#: (360)754-4612 Fax#: (360)7544848 GEOTECHNICAL TESTING LABORATORY _}Y ti 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 building location slopes are stable relative to deep- seated instability and will not be affected by the proposed structure if our recommendations are respected. The proposed structure will not undermine adjacent structures. Proper drainage control measures will reduce or eliminate the potential for erosion in this area and improve slope stability. I l The hazards of the landslide area can be minimized in such a manner as to prevent harm to property and public Ihealth and safety, and the project will cause no significant environmental impact. t . In general, the Hoodsport soils observed at the site may be suitable for use as structural fill material. Saturated soil conditions may be associated with these soils during or following extended periods of rainfall. However, to reduce I grading time and construction costs, we recommend that earthwork be undertaken during favorable weather I , conditions. I " Conventional construction equipment may be utilized for work at the site. Conventional spread footings may be utilized at the site for support of the structure. ., _ be•installet}f—tl* . r:F A vapor barrier is recommended for all slab-on-grades. Pertinent conclusions and geotechnical recommendations regarding the design and construction of the proposed single-family residence are presented below. LANDSLIDE— EROSION HAZARD AREAS CLASSIFICATION The Mason County Critical Areas Ordinance (17.01.100) defines a landslide hazard area as one containing slopes equal to or greater than 40 percent with more than a 10-foot vertical relief. The southeastern slope is in excess of 40 percent and the vertical relief is in excess of 10 feet. Based on this, this site does meet the technical criteria of a landslide hazard. The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977) describes the southern site area as Class 3. Class 3 is described as: 10011 Blomberg Street SW, Olympia,WA 98512 6 Phone 4: (360) 754-4612 Fax 4: (360) 7544848 GEOTECHNICAL TESTING LABORATORY Areas inferred to be unstable because slopes, generally greater than 15 percent, are underlain by weak, unstable materials in which old or recently active landslides have occurred. Includes r areas of sand and gravel on top of impermeable silt and clay, mostly along steep valley sides. I` The Mason County Critical Areas Ordinance(17.01.104)defines an erosion hazard area as: Areas in Mason County underlain by soils which are subject to severe erosion when disturbed. iSuch 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 7 of River Wash ("Ra') or Coastal Beaches ("Cg') and the following when they occur on slopes 15%or steeper: a. Alderwood gravelly sandy loam ("Ae"and "Ad'9 b. Cloquallum silt loam ("Cd') e. Harstine gravelly sandy loam ("Hb') d. Kitsap silt loam ("Kc') The soils at the site are mapped as Hoodsport gravelly sandy loam (Hg). This site does not meet the technical criteria of an erosion hazard area. 9 i SLOPE STABILITY Based on our field observations, explorations and our experience with the soil types encountered on the property, we conclude that although portions of the slopes on the lot exceed 100 percent, the site is generally stable relative to deep-seated failure in their present configuration. The Coastal Zone Atlas, Volume 9, Mason County (MA-3) maps the site as Vashon glacial till (Q,t). The till is a tough, dense material of low permeability. It provides excellent foundation support. The site slope stability is described as "unstable"at the building site. To prevent minor sliding, uncompacted fill material and any underlying vegetation shall be removed in order to I construct the foundation. 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. L f As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural processes that affect slope areas. 10011 Blomberg Street SW, Olympia,WA 98512 7 Phone#: (360) 7544612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY 1 - 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. it in processes can be managed and the risk reduced through proper construction of the residence. These destabilizing g proce manag gh p p Erosion control recommendations in the slope and buffer areas are provided in the `Building Setback" and "Erosion Control'sections of this report. t A building setback from landslide hazard areas is required unless evaluated and reduced by an engineering geologist or a licensed professional i engineer. Based on our geotechnical evaluation of the site and our experience in the area, a building ( setback will be needed for this lot. . � 30% or more) slope to the bottom of the footing should Setb" otherwise be observed. The building setback may be measured from the bottom of the footing to the face of the steep slope in accordance with the 2003 International Building Code(IBC). Peak Shear Stress vs. Normal Stress Sandy Loam 42° - 2500 1 j n 2000 w M O 1 f 1500 1.00 t p L (!1 l. 1000 1 500 -�-114 ton -at-12 ton -1--1 ton 0 0 500 1000 1500 2000 2500 0000 Normal Stress(W 10011 Blomberg Street SW, Olympia, WA 98512 8 Phone#: (360) 754-4612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 1. Slope stability was modeled using the GEO-SLOPE/W program (version 5.20) in both static and extreme dynamic conditions (c, = 0.3). Factors of safety were determined using Straight Site--Slope A Bishop's, Janbu, and the Analysis Method:Morgenstern-Price Morgenstern-Price methods. The Direction of Slip Movement: Left to Right glacial till was determined to have a Seismic Coefficient: Horizontal and Vertical unit weight of 131 pcf, cohesion of 200 psf, and a shear angle (�)of 42°. Under static conditions, the slopes = were stable to shallow failure. Under dynamic loading, the 3328 computations demonstrated that the ./;� cslope is not susceptible to surficial raveling or deep-seated failure. The . ` following figure illustrates the moment factor of safety for slope"A" Sao �--. 1.25� under the existing conditions. The 620 figure is the solution of greatest 500 ` concern and exhibits the need for a o 480 building setback of 30-feet from the 460 U,& 131 N crest(30%or more)of the slope. w 400 Pht 42 l°`� 200 420 400 0 25 50 75 100 125 150 175 200 225 250 275 300 325 360 375 400 Distance(ft) - As previously discussed, weathering, erosion and the resultant surficial sloughing and shallow landsliding are natural processes that affect slope areas. Surficial raveling and sloughing was observed onsite along the oversteepened roadside cut. To manage and reduce the potential for these natural processes, we recommend the following: I ' 1. E -of cones surface water or significant shed-flow onus th i s. 2. I �? j� tek zone unless tb3�� �or consoted + agfll. 3. ._ shaped(300/a or more)areas as lo 'ng tie stumps remain. z 7Ni t . w S J. t 10011 Blomberg Street SW, Olympia,WA 98512 9 Phone#: (360) 7544612 Fax#: (360)7544848 GEOTECHNICAL TESTING LABORATORY SEISMIC-LIQUEFACTION HA_?ARn According to the Seismic Zone Map of the United States contained in the 2003 International Building Code (IBC), the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g). 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 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 C to D. Site class C is a very stiff soil or soft rock and site class D is a stiff soil. 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, as defined by Table 1615.1.1 (IBC). This is based on the range of SPT (Standard Penetration Test) blow counts and/or probing with a %cinch diameter steel probe rod. The shallow soil n conditions were assumed to be representative for the site conditions beyond the depths explored. Based on our review of the subsurface conditions, we conclude that the site soils are only mildly susceptible to liquefaction. The near-surface soils are generally in a dense condition and the static water table is located well below the surface. 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. t_ EROSION CONTROL 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 and limited to the active construction areas. Yard landscaping around the home is permissible,but understory growth on the slopes should be encouraged as much as possible as a ( deterrent to erosion. Trees located on steep slopes may be removed only if the stumps remain to deter erosion. 'dil"�t fir� dil ate aihd ordt pertentiaL receiving illd ; but not be limited to, silt fences, berms and swales with ground (, cover/protection in exposed areas. A typical silt fence detail is included on Figure 2. Any re-contouring of the site will create a need for erosion control measures as listed above. EARTHWORK 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 stripping on the order of 6 to 12 inches will be necessary to remove the root zone and surficial soils containing organics. Areas with deeper, unsuitable organics should be expected in the vicinity of depressions or heavy vegetation. Stripping depths of up to 18 inches may occur in these areas. These materials may be stockpiled and later used for erosion control and landscaping. Materials that cannot be used for landscaping or erosion control should be removed from the project site. 10011 Blomberg Street SW, Olympia,WA 98512 10 Phone#: (360) 754-4612 Fax#: (360)754-4848 f . GEOTECHNICAL TESTING LABORATORY { Where placement of fill material is required, the exposed subgrade areas should be proof-rolled to a firm and 1 unyielding surface prior to placement of any fill. We recommend that trees be removed with the roots, unless located on a slope. Excavations for tree stump removal in any building area should be backfilled with structural fill, compacted to the density requirements described in the"Structural Fill"section of this report. 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. T STRUCTURAL MILL All fill material should be placed as structural fill. The structural fill should be placed in horizontal lifts of 1 appropriate thickness to allow adequate and uniform compaction of each lift. Fill should be compacted to at least 90 percent of MDD (maximum dry density as determined in accordance with ASTM D-1557) to within 2 feet of subgrade and 95 percent MDD in the upper 2 feet. ' The appropriate lift thickness will depend on the fill characteristics and compaction equipment used. lam: $eid sttttirL . . , ! s 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 5 percent (by weight) passing the No. 200 sieve based on that fraction passing the%-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. i 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. 5.. TIM �Y { .Mz. ♦s"- � �'"`{.j ��. � ;)5 �'�` * if .F 1 s 10011 BlombergStreet SW Olympia,WA 98512 1 � 1 Phone#: (360) 7544612 Fax#: (360)7544848 GEOTECBNICAL TESTING LABORATORY SUITABILITY OF ONSITE SOILS AS FILL Onsite soils may be considered for use as structural fill. In general, the native soils (sand, loam, and gravel) i 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. CUT AND FILL SLOPES i - 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 will likely 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. Flatter cut slopes will be necessary where significant raveling or seepage occurs. Surface drainage shall be directed away from all slope faces. All slopes should be seeded as soon as practical to facilitate the development of a protective vegetative cover or otherwise protected. FOUNDATION SUPPORT - Where foundation elements are located near slopes of 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. 1 . We recommend a minimum width for isolated footings and continuous wall footings to meet IBC. 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. 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 0.40 be used to calculate friction between the concrete and the underlying soil. Passive pressure may be determined using an allowable equivalent fluid density of 150 pef(pounds per cubic foot). We estimate that settlements of footings designed and constructed as recommended will be less than I inch, for the anticipated load conditions, with differential settlements between comparably loaded footings of/z inch or less. Most of the settlements should occur essentially as loads are being applied. However, disturbance of the foundation sub-grade during construction could result in larger settlements than predicted. 10011 Blomberg Street SW, Olympia, WA 98512 12 Phone#: (360) 7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 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 minimum 6- inch thickness of coarse sand and/or gravel containing less than 3 percent fines (by weight). The drainage material - should be placed in one lift and compacted to an unyielding condition. I ' A synthetic vapor barrier may 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. RETAINING WALLS Retaining walls may be utilized on the sloping portion of the site to retain fill material. The lateral pressures acting on the subgrade and retaining walls will depend upon the nature and density of the soil behind the wall. It is also dependent upon the presence or absence of hydrostatic pressure. If the adjacent exterior wall space is backfilled with clean granular, well-drained soil (washed rock), the design active pressure may be taken as 0.40 (coefficient). This design value assumes a level backslope and drained conditions as described below. Retaining walls located on or near the toe of a slope that extends up behind the wall should be designed for a lateral pressure, which includes the surcharge effects of the steep slope in proximity to the wall. Although not expected at this site,the following data is provided for planning purposes. For an irregular or composite slope,the equivalent slope angle may be determined by extending a line upward from the toe of the wall at an angle of 1 to 1 (Horizontal to Vertical) to a point where the line intersects the ground surface. The surcharge effects may be modeled by increasing the equivalent fluid pressure for flat ground by the f percentage given in the following table: SLOPE INCLINATION: EQUIVALENT FLUID PRESSURE f Slope Angle Percent Increase Equivalent Fluid Pressure Horizontal 0% 35 pcf 3H:1V 25% 44 pcf I ' 2H:1 V 50% 53 pcf j 1H:1V 75% 61 pcf If the walls are greater than 4 feet in height, exclusive of the footing, additional design considerations should be applied. Positive drainage, which controls the development of hydrostatic pressure,can be accomplished by placing a zone of coarse sand and gravel behind the walls. The granular drainage material should contain less than 5 percent fines. The drainage zone should extend horizontally at least 18 inches from the back of the wall. The drainage zone should also extend from the base of the wall to within 1 foot of the top of the wall. The drainage zone should be compacted to approximately 90 percent of the MDD. Over compaction should be avoided as this can lead to excessive lateral pressures. A perforated PVC pipe with a minimum diameter of 4 inches should be placed in the drainage zone along the base of the wall to direct accumulated water to an appropriate discharge location. 10011 Blomberg Street SW,Olympia,WA 98512 13 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY We recommend that a non-woven geotextile filter fabric be placed between the drainage material and the remaining { wall backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage zone can, with time, reduce the permeability of the granular material. The filter fabric should be placed in such a way that it fully separates the drainage material and the backfill, and should be extended over the top of the drainage zone. Lateral loads may be resisted by friction on the bases of footings and as passive pressure on the sides of footings and the buried portions of the wall. We recommend that an allowable coefficient of friction of 0.40 be used to calculate ' friction between the concrete and the underlying soil. RETAINING WALL ALTERNATIVES i Typically, block wall systems are more cost effective for long-term walls than the other options. Specific design criteria for these options can be provided at your request by the block manufacturers. i . SITE DRAINAGE All ground surfaces, pavements, and sidewalks should be sloped away from the residence and associated structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch basins and tight-lined to an appropriate infiltration area. We recommend that conventional roof drains be installed. Footing 1 drains shall be installed for the single-family residence. 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. 1 1 � stormu�at��r r a# ,b r tF�ib161jA&the s, portion of the site-by . fig)`t-fte. Drainage control measures are included on Figure 3. Onsite irrigation to lawn areas should be closely ! monitored. We do not expect any adverse affects on the recharge condition of the groundwater system. i t 1 r 10011 Blomberg Street SW, Olympia, WA 98512 14 Phone#: (360) 7544612 Fax#: (360) 7544848 GEOTECHNICAL TESTING LABORATORY 1 LIMITATIONS We have prepared this report for Mike Straight and members of his design team,to use in the design of a portion of this project. The data used in preparing this report, and this report, should be provided to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and interpretations are based on data from others and our site reconnaissance, and should not be construed as a warranty of the subsurface conditions. This ' report is quantified as a micro-study and not a macro-study. Geotechnical Testing Laboratory and its personnel cannot be responsible for unforeseen and widespread geologic events (such as earthquakes, large-scale faulting, and mass wasting)beyond the scope of this project. ' Variations in subsurface conditions are possible and may occur with time. A contingency for unanticipated P� m8 cY conditions should be included in the budget and schedule. Sufficient consultation with our firm during construction should continue, to confirm that the conditions encountered are consistent with those indicated by our observations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated,and to evaluate whether earthwork and foundation installation activities comply with our specifications. If our analysis and recommendations are followed, we do not anticipate any onsite or offsite impact from the proposed construction. It is our conclusion that potential landslide hazards can be overcome so as not to cause harm to property,public health and safety,or the environment. The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures,except as specifically described in our report for consideration in design. (y If there are any changes in the loads, grades, locations, configurations or types of facilities to be constructed, the l conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications,as appropriate. f Respectfully submitted, ti0 0� Wash�� GEOTECHNICAL TESTING LABORATORY �0 fHarold Parks, L.G.,L.E.G. 827 ♦y Senior Engineering Geologist HAROLD PARKS 7-3J—os' 10011 Blomberg Street SW, Olympia,WA 98512 15 Phone#: (360) 754-4612 Fax#: (360)7544848 Tog IMP ' �',til giros ;�► MaAll IBM ! a f LTER FABRIC MATERIAL OTWIDE ROLLS SE STAPLES OR WIRE PNGTOATTACH Geotec h nic al WBRIC TO WIRE FABRIC REOLIGAI)GEVRE AUE FABRIC OR EOLIVN.BJT Testing F Laboratory 6 MAX OR BURY BOTTOM OF RCER MAIERI AL IN 8"x17 TPET 6` _ 2'Cr -ACE 5-P 17 Er MIN 7%4"WOOD Frl5T5 "LT STEEL FENOE WSTS Geotechnical Services CHASEDINACONRNLIORISROLLCUTTO Q'e Y Q"`^ Services TOAVODUSEOFJCMS VABR.DINTS Testing SefVICeS TH SHALL BE SRICIDTOGERSi ONLY AT IMIM STING OVERLAP AID SECURELY if POST, AAMLM OF FEET MART AND DRIVEN )ONS MOF30I IC ES1. 'D APPRO)OMATAY 8 NOIES WIDE*0 12 10011 Blomberg St.SW E OF POSTS AIDLIPSLOPE FROM THE BARRER. Olympia,WA 98512 FILTER FABRIC YToTLISM HEEuFao�PESCE Phone:(360)754-4612 gJTY WIRE STARES AT LEAST i INCH Fax:(360)754-4848 IGS.THEWIRESALLEJOEDMTOIHE 1ES AND SHALL NOTEJ(TE OMORETHOW 36 GROIIDSJRFAC= LTER FABRIC SHALL LE STAPLED ORWIRED Date: 05/13/2005 S OF FABRIC SHALL BE EK78,019D IC SHALL NOT EATED MORE THAN 35 Designed by: LL iiwT�REES. ��F"BRICSHALL Drawn by: LL ER FABRIC AND CLOSER POST SPAONG IS Checked by: LL MINATM IN WON SST MoRWIRE MAP D YTOTHEE Dwg#:05-13-05-042 NSIONS OR ABOVE NOTES APPLYING. L NOT BE REAO'm?FORETIELPSLO E _Y STIHUIID. L BE INSPECTED 44.E)IAT6Y AFTER EACH Y DLMING PROLONOEDRAIFALL ANY MNEMM®IATB.Y. mt S DOLL BE NR PACE PRIOR TO THE )N.THE PROJBT ENGINEER ANDTHEC"M ET1EµSTNLATIONOF T PRIOR TO BEWNNG LOHATRUCOOIN. S ARE NOT LIMi®TOR£RBAS :TOR IS RESPONSIBLE FOR THE W CE OF ALL MOS70N CONTROLAEASLIRES. JALL ETAXENRAINAGEFAffIAGR PROJECT NAME:{ALLBETAREIR APREVENTMGRATION TIES MIKE STRAIGHT ¢DAILY SMAEILLA NCE OF ALL EROSION 4RE ANY NECESSARY RBNRS OR ADDITIONS 345 SHAR LANE NORTH IEASARES.THECCNTRAMORS/ALLRROWDE OL MEASLF&S ASDETERM4IE)IECESRY LILLIWAUP,WASHINGTON QOOR THE PROJECT 9"3ER.FAILURE "IDS`" 84&nrS`MNT LEI PARCEL 323093400030 INwP OJECTO NER('LEV1® RDGRPROJECTDWrER. OVBMBER TO MARCH ALLCISRIRBED SOILS p�IjLy�I�� 43HOURSAFTER STOP OFMW 8ROSON Rv�N7V1 ro.NMUDE BUT NOT BE L MED TO, '.EA ITRCIILYNG SOIL PILES WITH ATTING,JUTE MATTING,STRAW AU_CH, F THE CSTUR®AREAS SHALL TNe AS SHALL BE CEO®REGLAARLY COVMAGE IS COALEM AREAS SHALL BEEf16RBO AS RECLIRED NLL NOT BE NLOV�.IF ANY SOIL IS ..IT SHALL BE RE.IOVIEDBYTHE ENO PRTHER TRACGW OF MDWILL THEN i OR WASHING OF THE VIEICL STALES Y SI." BAN ON A DO WN30PE OF MORE THAN 5 LTONETNE L IE PLACED ON THE LRNL SIDE OF TRENCHES ES STALL BE DISCHARGEDIN AMANER THAT WILL ANNO STREAMS,DRNUBE SYST84OR SCALE:1 Mich=50 feet ECBVING RUNOFF FROM THE PROJECT DURING ROTECTED SO THAT SE M NTlICBJ WATER NTERINO THE OONYEI'MICE SYSTEM, SILTA ATf•LYAOIACERTTOMES7E FIGURE 2 ,gITATION. L BE SEEDED OR SODDED OD,H CN R SHALL BE RESPONSIBLE BRSR7ETHAT {E DISTUR®AREAS IS THAT NEDMENTORPL SITE PLAN EDIMETA IONIS ERFALISHED T� L VEGE'TMION IS ESTABLISHED 1/2 INCH MINIMUM DIAMETER STEEL ROD (STRAP)CLAMPED SECURELY TO PIPE CORRUGATED TIGHTLINE 4 INCH MINIMUM,6 INCH SUGGESTED p F RR s qM 70F 111 ��r:�\•�Y�ti;-! •:��'r �-:,..L�Y;.t`..a.t'4-.�^ti'.. �.Z N:.t..."• :R� -- _:i.:.na•a�^ice��;�`:�r�''T:.:;.;.�;t �•' 1' _ '-�..:•:s.- - L •' R �t� -Ny.�sn•�T��sy..vn�n•2 L n.:.::�"..q.`. .`�•:.�.-v i Gf TIGHTLINE ANCHORED WITH TWO, 3 FOOT REBAR LENGTHS OR BOLTS. r- i FLARE END SECTION QUARRY SPALL - i..�•.X•�a ;afoot lglLv Ft c'�:� .y' OR ENERGY DISPERSION DEVICE ;-^`:F"5 ':`e-;'= ;: '; 4`�''=y'?� "-'_•.t 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 Servioes 1001t Bbmb&MSt SW ot,mw QA/QCServices Fho (360)754-4612 Testing Services 1.(3e0)754-480 Not to scale DRAINAGE DETAILS