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HomeMy WebLinkAboutSherwood Creek - GRD Engineering / Geo-Tech Reports - 9/19/2005 Geotechnical Report 260 East Sherwood Creek Road Allyn, Washington Prepared for: Jack Johnson Construction, Inc. Belfair, WA by Geotechnical Testing Laboratory Olympia, Washington September 19, 2005 GEOTECHNICAL TESTING LABORATORY .TACK JOHNSON CONSTRUCTION,INC. P.O. Box 1119 BELFAIR,WA 98528 RE: GEOTECHNICAL REPORT 260 EAST SHERWOOD CREEK ROAD ALLYN,WASHINGTON PARCELS 122203300210, 122292200320, 122203390221, 122203390222, 122203390223, & 122203390224 N47022.564' W122050.582' INTRODUCTION This report summarizes the results of our geotechnical consulting services for the proposed selective logging and nine single-family residences to be located at the above referenced site, approximately 1.0 mile southwest of Allyn, Washington. The 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 nine single-family residences. The 14.1-acre site will be accessed by an existing driveway from Sherwood Creek Road. In general, grading will consist of the excavation of the foundation, footings, and partial road relocation along the northern property line. Selective logging will occur throughout the site;the underbrush will remain. ,p The site slopes south and southeast from a nearly level upper area(proposed building locations)toward Sherwood Creek Road. Fill material was observed along the outer edge of the proposed building locations(locations 1, 2,3, 6, & 7) where historical grading created building pads. The steepest slope measured onsite was in excess of 100 percent. Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Critical Areas Ordinance. 10011 Blomberg Street SW,Olympia,WA 98512 1 Phone#: (360) 7544612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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: 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 sparse residential development in the glacial uplands overlooking Sherwood Creek. The site has southern and southeastern exposure. We conducted a reconnaissance of the site area on May 26 and August 24, 2005. Site elevations range from approximately 25 to 205 feet. The site will be serviced by community sewer. The proposed building locations have been previously cleared of vegetation. We observed no exposed soil on the southern slopes. The site slopes are vegetated with a well-mixed variety of vegetation common to the Northwest. The vegetation includes fir, cedar, alder, maple, and madrone trees as well as Scot's broom, sword ferns, bracken ferns, horsetail ferns, Oregon grape, skunk cabbage, daisy, nettles, wild rose, foxglove, salal, ivy, huckleberry, blackberry, and grasses. � H -71T It 4. `.^ - %;�• 10011 Blomberg Street SW, Olympia, WA 98512 2 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY At the time of the site visit,we observed no evidence of active surface erosion at or around the proposed building locations. Minor slope instability was observed along the slopes of the proposed building locations. Minor sloughing and raveling were observed along the toe of the south facing slopes. Onsite trees were observed to be mostly straight and vertical after early pistol butting. Surficial creep was displayed by bowed trees near the top of the slope where the surficial soils have slid over the glacial till, see photos below. Surface water flow was observed along the toe of the slopes and along the roadside ditch. Minor ponding was present at the western proposed building location (#7), see photo right. Groundwater was expressed by seepage along the toe of the slope. The general topography of the site area indicates that drainage is toward the south and southeast. 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 9,000 and 11,000 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 northwestern site soils as a Sinclair shotty loam, 5 to 15 percent slopes (So), at the proposed building location. The Sinclair soils have typically developed from very compact Vashon gravelly till. Surface drainage is well to moderately well established. Internal drainage is restricted by the substratum of cemented till. Typically,there is no occurrence of a high water table. We observed no active erosion or slope disturbance in the site area during our reconnaissance. The soils are not considered hydric. i7x y "fir " . b low j 1 �` �. ...._2 a�•L -.. yes ,f .+„y,�. � }F � 10011 Blomberg Street SW,Olympia, WA 98512 3 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY The Soil Survey of Mason County, USDA Soil Conservation Service (1960) has mapped the lower(southern) site soils as an Everett gravelly loamy sand, 0 to 5 percent slopes (Ed). The Everett soils are described as very deep, somewhat excessively drained soil on terraces and outwash plains formed in the glacial outwash stage of the most recent Fraser glaciation. These Everett soils coarsen with depth. Permeability is rapid (up to 20 inches per hour) with a high rate of water transmission. These soils are typically classified as "Hydrologic Group A" relative to surficial runoff. The water capacity for plants is low. The soils are further characterized by having medium runoff potential and moderate water erosion potential. Shrink-swell potential is described as low due to the low organic content. The Soil Survey of Mason County, USDA Soil Conservation Service(1960)has mapped the mid slope site soils as an Alderwood gravelly sandy loam, 15 to 30 percent slopes (Ac). The Alderwood soil typically formed from glacial advance outwash. The soil is described as having good natural drainage. Typically,there is no occurrence of a high water table. Internal drainage is described as medium. An erosion hazard may exist if the vegetation is removed-, otherwise,the soil has a low erosion hazard in its present condition. Cementation is usually present. a ♦ Y The Geologic Map of Washington—Northwest Quadrant(2002)has mapped the northern (upper) site geology as glacial till deposits (Qgt) of continental glacial origin. The report reads: Till— Unsorted, unstratifred, highly compacted mixture of clay, silt, sand, gravel, and boulders deposited by glacial ice; may contain r interbedded stratified sand, silt, and gravel. Includes part of the Vashon Drift undivided. JA { - 79 _�.� J` L� .-� � vt'7. _.:� � *, �`" tti� .off >��✓ �T J'�✓ ~ � yx' 10011 Blomberg Street SW,Olympia,WA 98512 4 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY The Geologic Map of Washington — Northwest Quadrant (2002) has mapped the southern (lower) site geology as advance outwash deposits ` (Qga)of continental glacial origin. The report reads: Advance outwash—Glaciofluvial sand and gravel and lacustrine clay, silt, and sand deposited during the advance of glaciers; sandy units commonly thick, well sorted, and fine grained, with interlayered coarser sand, gravel, and cobbles; locally contains nonglacial sediments and deposits mapped as transitional -- between glacial and nonglacial. Includes the Colvos and Esperance Sand Members of the Vashon Drift and part of the Vashon Drift undivided ff. tom': ���? I �.•'� �- ��, � �v ,'der- -. �.✓" f 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 locations. Static groundwater is unknown but presumed deep(-60 feet)at the proposed building locations. SUBSURFACE CONDITIONS In general, undisturbed dense Sinclair shotty loam was observed throughout the proposed building locations. Groundwater seepage was observed along the toe of the slope. Based on the site topography and the nature of the near surface soil, seasonally perched groundwater conditions may be expected during periods of extended wet weather. 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 relief occur on portions of the site, Mason County requires that a geotechnical report be completed according to the Critical Areas Ordinance. The near-surface soils are in a dense to very dense condition except at the ground surface. The surficial soils are generally in a medium dense condition. 1001 1 Blomberg Street SW,Olympia, WA 98512 5 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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. Weathering, erosion, and the resultant sloughing and shallow landsliding are natural processes that can affect steep slope areas. Instability of this nature is typically confined to the upper weathered or disturbed zone, which has been disturbed and has a lower strength. Except for minor ponding, no surface water or active erosion was observed at the proposed building locations. 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. a 4 . C - Toe of Slope 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 overcome in such a manner as to prevent harm to property and public health and safety, and the project will cause no significant environmental impact. In general,the Vashon glacial till soils observed at the site are 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 structures 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. 10011 Blomberg Street SW,Olympia,WA 98512 6 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 small south-facing slope is in excess of 100 percent and the vertical relief is in excess of 10 feet. Most slopes are approximately 60 percent. 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 northern site area as Class 1. Class 1 is expressed as: Areas believed to be stable. Slopes generally less than 15 percent, but may be greater locally in areas too small to be shown at the map scale. Largely comprises rolling uplands underlain by very stable material such as young glacial till, mantled in places by a thin layer of sandy gravel or other permeable material; also includes flood plains, deltas, alluvial fans, and some beach deposits. Class 1 areas immediately adjacent to steep slopes of class 3 areas may be threatened by potential landsliding. Normal, proper engineering practices generally are adequate to insure stability in these areas. The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977)describes the lower site area as Class 2. Class 2 is described as, Areas believed to be stable under normal conditions, but may become unstable if disturbed by man's activities, if slope is oversteepened by erosion, or if subjected to strong seismic shaking. Slopes generally steeper than 15 percent, but may be less in some areas of weak geologic materials. Includes areas underlain by: well-drained sand and gravel, mostly on valley sides that lack known slope failures;glacial till with steep slopes;and bedrock 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') c. Harstine gravelly sandy loam ("Hb') d. Kitsap silt loam("Kc') The central site soils are mapped as Alderwood gravelly sandy loam (Ac). This site does meet the technical criteria of an erosion hazard area. 10011 Blomberg Street SW,Olympia, WA 98512 7 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 its present configuration. The Coastal Zone Atlas, Volume 9, Mason County _ - (MA-12) maps the site as Vashon Advance Outwash (Q„a) along the toe of the slope. The chance of flooding is less than one percent. s Permeability is described as high, while runoff potential is low. Infiltration is moderate on natural slopes and high on cut slopes. Springs at the bases of slopes are common (springs or seeps were z observed during the site reconnaissance). The slope stability is described as"intermediate." =� The Coastal Zone Atlas, Volume 9, Mason County r j (MA-12) maps the site as Vashon glacial till throughout the northern site area. Foundation z stability is described as "excellent." Seismic r , stability is described as"good." The slope stability is described as"stable." K i rub., To prevent minor sliding, uncompacted fill � . material and any underlying vegetation shall be s i:24"0 /% • f I M0. removed in order to construct the foundation. ) W ,m „m M_ Excavation and backfilling 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 Water in Roadside Ditch from Toe of Slope 10011 Blomberg Street SW, Olympia, WA 98512 8 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural processes that affect slope areas. Significant weathering typically occurs in the upper 2 to 3 feet and is the result of oxidation,root penetration,wet/dry cycles and freeze/thaw cycles. Over excavation may be necessary to ensure the removal of deleterious material. These processes can be managed and the risk reduced through proper construction of the residence. Erosion control recommendations in the slope and buffer areas are provided in the "Building Setback" and "Erosion Control" sections of this report. 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 Setback Setback this tract. A building setback from the crest of the slope to the bottom of the footings should otherwise be observed. The building setback(see following page) 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). An additional building setback of 15 feet will be required from the toe of steep slopes. All foundation elements shall be founded in native material or engineered fill material. For the individual building locations, setbacks for the specific building locations are described below. Peak Shear Stress vs. Normal Stress 2500 2000 37' 0 N N W 1500 UJ L l� Q1 1000 Y l4 a +1/4 ton 500 �-1/2 ton �-1 ton 0 0 500 1000 1500 2000 2500 Normal Stress (psQ 10011 Blomberg Street SW,Olympia, WA 98512 9 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 (Ca = 0.3). Factors of safety were determined using Bishop's, Janbu, and the Morgenstern-Price methods. The glacial material was determined to have a unit weight of 132 pcf, cohesion of 200 psf, and a shear angle (�) of 37°. Under static conditions, the steep slopes (>60 percent) were moderately unstable. Under dynamic loading,the 3328 computations demonstrated that the slopes are susceptible to surficial raveling or deep- seated failure. The following figures illustrate the moment factors of safety for the four slope profiles under the existing conditions. The following figures are the solutions of greatest concern and exhibit the need for a building setback of 30 from the crest of the slopes for building sites 2, 3,4, 5, 6, and 7. A building setback of 40 feet from the crest of the slope will be required for building site 1. A building setback of 15 feet from the crest of the slope will be required for building sites 8 and 9. Daylight basement designs will not require a building setback from the toe of slopes. Johnson Site -- Site 1 Analysis Method: Morgenstern-Price Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vjrti al y , •� • 0.96 180 160 140 120 0 100 Glacial Material M 80 Unit Weight: 132 > Cohesion: 200 W 60 Phi: 37 40 20 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 Distance (ft) 10011 Blomberg Street SW,Olympia, WA 98512 10 Phone#: (360) 754-4612 Fax#: (360)754-4848 G EOTECHNICAL TESTING LABORATORY Johnson Site—Site 2 Analysis Method: Morgenstern-Price „!! • /� Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Verfic I R� 092 !, 180 . 180 :\ •140 / 120 L Glacial Material O 100 Unit Weight:132 M 80 Cohesion:200 N Phi:37 60 W 40 = N 20 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 Distance(ft) Johnson Site—Site 3 Analysis Method: Morgenstern-Price , Direction of Slip Movement: Left to Right . Seismic Coefficient: Horizontal and Vertica ' 0 .92 A 220 -- 200 180 _ ' ' o°f 160 $ 140 p 120 :- Glacial Material > 100 Unit Weight:132 N 80 Cohesion:200 W Phi:37 60 40 N 20 0 0 50 100 150 200 250 300 350 400 450 50i Distance (ft) 1001 1 Blomberg Street SW, Olympia, WA 98512 1 1 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Johnson Site--Site 4 Analysis Method: Morgenstern-Price 0,87 Direction of Slip Movement: Left to Rig4 Seismic Coefficient: Horizontal and V oal /� /• 00 ,1,11 �t 180 160 140 o 12? O ZZ Glacial Material > Unit Weight:132 80 Cohesion:200 W Phi:37 0 50 100 150 200 250 300 350 400 450 500 Distance(ft) Johnson Site--Site 5 , , .. . Analysis Method: Morgenstern- ric Direction of Slip Movement: Le to Right ' Seismic Coefficient: Horizonfa a Ve''ca zoo 180 < 150 � u 120 Glacial Material M 100 Unit Weight:132 N 81 _ Cohesion:200 W — Phi:37 100 15C 90 250 300 350 400 450 500 Distance(ft) 10011 Blomberg Street SW, Olympia, WA 98512 12 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Johnson Site -- Site 6 • . < Analysis Method: Morgenstern-Price • /I • j Direction of Slip Movement: Left to Right • :93 Seismic Coefficient: Horizontal and Ve I • • • • 250 230 210 $ 190 p 170 CID 150 N Glacial Material W 130 Unit Weight:132 110 Cohesion:200 Phi:37 90 70 0 100 150 200 250 300 350 400 450 500 Distance (ft) Johnson Site—Site 7 Analysis Method: Morgenstern-Price e , Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vertical .F• 220 200 160 .� 160 140 O 120 Glacial Material ip 100 Unit Weight 132 60 Cohesion 200 W 60 Phi:37 40 20 0 0 SCt 100 50 00 250 300 350 400 450 500 550 600 650 700 750 Distance(ft) 10011 Blomberg Street SW, Olympia, WA 98512 13 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Johnson Site -- Site 9 Analysis Method: Morgenstern-Price Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vertical . . . . . . . . . . 1.00 220 200 180 160 _.- 140 CO 120 +� Glacial Material 100 Unit Weight: 132 80 Cohesion:200 W Phi: 37 60 40 20 0 0 50 100 150 200 250 300 350 400 450 500 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 only observed along the toe of the south-facing slope. Slumping was observed along the toe of the south-facing slope. 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 areas as long as the stumps remain. 10011 Blomberg Street SW, Olympia, WA 98512 14 Phone#: (360) 754-4612 Fax#: (360) 754-4848 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 northern site area as having a very low liquefaction potential. The Liquefaction Susceptibility Map of Mason County, Washington by Palmer, Magsino, Poelstra, Bilderback, Folger,and Niggemann(September 2004)maps the southern 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 ''/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 not 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 prod { Toe of Slope 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 on the slope 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. 10011 Blomberg Street SW,Olympia,WA 98512 15 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 4. Any re-contouring of the site will create a need for erosion control measures as listed above, see Figure 5. Tce of Slope 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 8 to 14 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. 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. 10011 Blomberg Street SW,Olympia, WA 98512 16 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 7 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. P 'yi^1 n �. Cam• - � • , �4��\ ' _, _ '7�!''�`+ •gam• Proposed Building Location 1 "t,.i,� ��� - Proposed Building Location 1 10011 Blomberg Street SW,Olympia,WA 98512 17 Phone#:(360)754-4612 Fax#: (360)754-4848 ' it-•�� • - ',. s-yp � '-� r ��'2 y _ �'•- ti' .. �:. I'�^ ` �+!� is2R�+ 4 ;'tie• .��� !tV � �'�" J.��,�� .gyp �'k - ia.��+l� n� 'arProposed ffililding 1,ocationrW y TZT., Proposed Building Location id �1e♦ r_.. ' . . -Jew 1p�� va 2�. -1,4 SCAN � �� k� _ '� s ; ��3 sir - ��.�'• -o h.. Proposed n till" t 1'' Proposed Building Location 4 ed Building Location 5 = t e VTR, n•. • � �qj y� , •�• -, ry sue.,•* „ .. a �; - ,�}'•jRti:b'i, i� -_4,';:',> � � � �� � j � ` O'i�iS 'fit "�:'�K � -�� 4.,., w% A IAZ 00 - s Its At �. Proposed GEOTECHNICAL TESTING LABORATORY Zw ^l r 1 i `"', � ♦�., ,A V ,. ✓ v Proposed Building Location 8 10011 Blomberg Street SW,Olympia,WA 98512 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY _ `fv Lh � 4 JF Proposed Building Location 9 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 onsite 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 between 5 and 30 percent, the footings should be located a minimum of 2 times the footing width from the slope face(horizontally), and founded in medium dense or denser native soils or properly prepared structural fill. 10011 Blomberg Street SW,Olympia, WA 98512 21 Phone#: (360)7544612 Fax#: (360)7544848 GEOTECHNICAL TESTING LABORATORY t Fill Material Along Edge at Proposed Building Locations 6&7 We recommend a minimum width for isolated and continuous wall footings to meet IBC 2003. 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. Active pressure may be determined using an allowable equivalent fluid density of 150 pcf(pounds per cubic foot). We estimate that settlements of footings designed and constructed as recommended will be less than 1 inch, for the anticipated load conditions, with differential settlements between comparably loaded footings of Yz inch or less. Most of the settlements should occur essentially as loads are being applied. However, disturbance of the foundation subgrade during construction could result in larger settlements than predicted. PIN PILES To reduce building setbacks, we suggest that pin piles be utilized to anchor the foundation to the underlying soils. Pin piles are driven into the soil until refusal is achieved. The pin piles are driven with an 80 to 90 pound jackhammer to whatever depth is necessary to reach the specified driving resistance (1 inch or less of penetration for one minute of continuous driving). Standard threaded couplings may be used to connect pipe sections. The pipe sections should be butted together in about the center of the coupling to avoid stripping the threads during driving. If hard driving is anticipated, the ends of the pipe sections can be machined square to provide more surface area for stress transfer during driving. 10011 Blomberg Street SW,Olympia,WA 98512 22 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY The piles are to be driven within the proposed footing. The spacing between piles is to be 3 feet center to center beneath typical structure walls to 1.5 feet center to center for supporting heavier elements such as fireplaces, brick trimmed walls, or to a load of 2000 pounds per 2-inch pile. The piles are installed vertically. Following driving, the piles are cut to length to allow for clearance of the pile cap off the ground. Rebar shall be used as shown on the following diagram. Concrete is then placed within the footing forms surrounding the piles. If pin piles are utilized, building setback distances may be reduced by half or 50 percent. Typical Pin Pile Drawing #3 Rebar Footing Form Footing Form 2 in.min. Pipe Pin Pile #3 Rebar Pipe Pin Pile 2 in.Minimum 10011 Blomberg Street SW, Olympia, WA 98512 23 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. ''7�qy .q 4, Well-Cemented Glacial Till Found Offsite f r 4_ 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 determined using an active pressure coefficient equal to 0.25 (Ka = 0.25). 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 1 H:1 V 75% 61 pcf 10011 Blomberg Street SW,Olympia, WA 98512 24 Phone#:(360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY If the walls are greater than 8 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. 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,with time, can 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. Passive pressure may be determined by using a passive pressure coefficient equal to 4(Kp=4). Factors of safety have been applied to these values. 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 drains should not be connected to the footing drains. 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 southern 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. 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. SEPTIC IMPACT The site will be serviced by the local community sewer system. 10011 Blomberg Street SW, Olympia,WA 98512 25 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY PROPOSED LOGGING Selective logging is proposed throughout the site. Selective tree removal along slopes may occur if one end of the felled tree is elevated when dragging or pulling to the landing area. The underbrush vegetation must remain with minimal disturbance. We expect impacts to slope stability to be negligible. Sediment migration must not leave the site. Additionally, all hazard trees (leaning, rotten, or dead) may be removed to increase slope stability. All logging must be performed by a qualified or licensed logging professional. LIMITATIONS We have prepared this report for Jack Johnson 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. 10011 Blomberg Street SW,Olympia, WA 98512 26 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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. Respectfully submitted, t0 C�Was6l GEOTECHNICAL TESTING LABORATORY y~� fog Harold Parks, L.G., L.E.G. Er4onev p(3e l lot Senior Engineering Geologist 827 �y ed G eo�o HAROLD PARKS OP 4-31 - 0(o 10011 Blomberg Street SW, Olympia, WA 98512 27 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Vicinity Map /// ( fill 9 JAM lbw /r r t '"� f i � i �Y J� rSON.SITE� 3e � J f _ �( }' nl• r M/51 TJ 7 l 1,� RROCks IN Figure 1 10011 Blomberg Street SW, Olympia,WA 98512 Phone#: (360) 7544612 Fax#: (360) 754-4848 Geotechnical J -JJ Testing 120' , \ ' == Laboratory i .PROPOSED \�.�.� ♦� �JI'/\'/( �'. `tBUILDING _1 ntk LOCAAON N % ��84� J \✓\ O (/ BUILDING / \ 1 l l SI T F E s46 �- Geotechnical Services QA/QC Services Testing Services if fill// I/ ^�v cJ �`'G� � ;/.%/'i%i i 11 f ' _ lr^j i\•- ,: I `r' ,/^ �—`r— 10011 Blomberg St.SW Olympia,WA 98512 7 120. j'1 /l%I' 11/7,!(/' \Z r /- Phone:(360)754-4612 \ —\ —————— Fax:(360)754-4848 SI 1 Date: 05/25/2005 J cat l) I I I IN�S ` \ i �—————— ��e Designed by: MFW III ; 1 1\\�\ f\1 \\ I Drawn by: ZXW / Revised by: LL I t I f \\ �\\ \n )lr, "t__ Dwg#:05-25-05-045 N.f It ` -MARIES APPROXIMATE U & LOCATED. ti'i 11 r' i/i 1 '��/r/ t/ /W I r } (71/ �.rl�,�'%,"�,�_; UN 2E ,New 1929. !' I %1%///r l%'r Ir) -\1��-/ R1H zav&NA10 N \ . / ROTA70 TO S2'p7L \- 1 r PROJECT NAME: JACK JOHNSON �I ( � J--�, �r l� \ ,� \ KNUDSEN TRACTS ALLYN,WASHINGTON rf-��--L� sions: 3Q K,1 \\lc if' i Revi 05/31/05 1 r -\ \1`1 \I \\ I\\) t 11 \I\\1 \ \\ <� / A.E.S. CONSI/L TAN7S / , }�/ 3472 NW LOWELL SILVERDALE• WA 98383 — t i i/%l/' �`/ /'%l M 1'JJ�,l ; (380)-692-6400 ' A", \ I ( 1 ( ^` SC7LLE:1 klch=100 toot A �._-\`�\I \\� •' / J ! / \ N. FIGURE 2 \ 1 \ ( / SITE PLAN 1/2 INCH MINIMUM DIAMETER STEEL ROD (STRAP)CLAMPED SECURELY TO PIPE CORRUGATED TIGHTLINE 4 INCH M�NiM�M MINIMUM,6 INCH SUGGESTED qv .'' TIGHTLINE ANCHORED WITH TWO, 3 FOOT REBAR LENGTHS OR BOLTS. FLARE END SECTION - -- � QUARRY SPALL 2� OR ENERGY ,: .�.' •'•M1 rv:: ��; a-;: _.a;-?i'•'%'?+-_"y+--' 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 C,Wtedmical Services +oo„ewobr,sc sw QaQc services °""W,W"�'Z FIGURE 3 Testing Services FFi`i)7� ' 'Z Not to scale DRAINAGE DETAMS FILTER FABRIC MATERIAL 60"WIDE ROLLS USE STAPLES OR WIRE RING TO ATTACH FABRIC TO WIRE 2"X2"X14 GAUGE WIRE FABRIC OR EQUIVALENT T2'0" //\\\� URFACE ////\\\ 2 6' __.__................ .. __._ d..L-....._ 6'MAX 2"X4"WOOD POSTS,STANDARD OR BURY BOTTOM OF FILTER BETTER OR EQUAL ALTERNATE: MATERIAL IN 8"X12"TRENCH STEEL FENCE POSTS FILTER FABRIC ---- --_ 6" 2"X2"X14 GAUGE WIRE FABRIC OR EQUIVALENT -- - GROUND SURFACE 5'-0" PROVIDE 3/4"-1 1/2"WASHED —� GRAVEL BACKFILL IN TRENCH 12" AND ON BOTH SIDES OF FILTER FENCE FABRIC ON THE SURFACE 6"IMIN 2"X4"WOOD POSTS ALT STEEL FENCE POSTS FILTER FABRIC FENCE NOTES: 1- FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS. WHEN JOINTS ARE NECESSARY,FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT BOTH ENDS TO THE POST. 2. POSTS SHALL BE SPACED A MAXIMUM OF 6 FEET APART AND DRIVEN SECURELY INTO THE GROUND(MINIMUM OF 30 INCHES). 3, A TRENCH SHALL BE EXCAVATED APPROXIMATELY 8 INCHES WIDE AND 12 INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER 4, WHEN STANDARD STRENGTH FILTER FABRIC IS USED,A WIRE MESH SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE OF THE POSTS USING HEAVY-DUTY WIRE STAPLES AT LEAST 1 INCH LONG,TIE WIRES OR HOG RINGS. THE WIRE SHALL EXTEND INTO THE TRENCH A MINIMUM OF 4 INCHES AND SHALL NOT EXTEND MORE THAN 36 INCHES ABOVE THE ORIGINAL GROUND SURFACE. 5, THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE AND 20 INCHES OF FABRIC SHALL BE EXTENDED INTO THE TRENCH THE FABRIC SHALL NOT EXTEND MORE THAN 36 INCHES ABOVE THE ORIGINAL GROUND SURFACE. FILTER FABRIC SHALL NOT BE STAPLED TO THE EXISTING TREES 6, WHEN EXTRA-STRENGTH FILTER FABRIC AND CLOSER POST SPACING IS USED,THE WIRE MESH SUPPORT FENCE MAP BE ELIMINATED,IN SUCH A CASE,THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THE POSTS WITH ALL OTHER PROVISIONS OR ABOVE NOTES APPLYING. 7. FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE UPSLOPE AREA HAS BEEN PERMANENTLY STABILIZED 8. FILTER FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL. ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY. Geotechnical Testing Laboratory Geote0nical Services 10011 Blortba9 Sl.SW QA/QC Services � Olrm ,WA 96512 FIGURE 4 Ph—(360)754-4612 Testing Services Fe (360)7544646 Not to scale SILT FENCE DIAGRAM GENERAL EROSION CONTROL NOTES: 1. EROSION CONTROL MEASURES SHALL BE IN PLACE PRIOR TO THE BEGINNING OF CONSTRUCTION. THE PROJECT ENGINEER AND THE COUNTY SHALL INSPECT AND APPROVE THE INSTALLATION OF EROSION CONTROL MEASURES PRIOR TO BEGINNING CONSTRUCTION. 2. EROSION CONTROL MEASURES ARE NOT LIMITED TO THE ITEMS ON THIS PLAN. THE CONTRACTOR IS RESPONSIBLE FOR THE INSTALLATION AND MAINTAINANCE OF ALL EROSION CONTROL MEASURES. NO SILTATION OF EXISTING OR PROPOSED DRAINAGE FACILITIES SHALL BE ALLOWED. CARE SHALL BE TAKEN TO PREVENT MIGRATION OF SILTS TO OFF SITE PROPERTIES. 3. THE CONTRACTOR SHALL MAKE DAILY SURVEILLANCE OF ALL EROSION CONTROL MEASURES AND MAKE ANY NECESSARY REPAIRS OR ADDITIONS TO THE EROSION CONTROL MEASURES. THE CONTRACTOR SHALL PROVIDE ADDITIONAL EROSION CONTROL MEASURES AS DETERMINED NECESSARY BY THE COUNTY INSPECTOR AND/OR THE PROJECT ENGINEER. FAILURE TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL REQUIREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED AGAINST THE CONTRACTOR AND/OR PROJECT OWNER. 4. DURING THE WET SEASON (NOVEMBER TO MARCH)ALL DISTURBED SOILS SHALL BE STABILIZED WITHIN 48 HOURS AFTER STOP OF WORK. EROSION CONTROL MEASURES SHALL INCLUDE, BUT NOT BE LIMITED TO, COVERING THE EFFECTED AREA INCLUDING SPOIL PILES WITH PLASTIC SHEETING, STRAW MATTING,JUTE MATTING,STRAW MULCH, OR WOOD CHIPS. SEEDING OF THE DISTURBED AREAS SHALL TAKE PLACE AS WEATHER PERMITS. 5. ALL SEEDED OR SODDED AREAS SHALL BE CHECKED REGULARLY TO MAKE SURE VEGETATIVE COVERAGE IS COMLETE. AREAS SHALL BE REPAIRED, RESEEDED,AND FERTILIZED AS REQUIRED. 6. TRACKING OF SOIL OFFSITE WILL NOT BE ALLOWED. IF ANY SOIL IS TRACKED ONTO A COUNTY STREET, IT SHALL BE REMOVED BY THE END OF THAT WORKING DAY. ANY FURTHER TRACKING OF MUD WILL THEN BE PREVENTED BY SWEEPING OR WASHING OF THE VEHICLES TIRES BEFORE DRIVING ON A COUNTY STREET. 7. NO MORE THAN 500 LF OF TRENCH ON A DOWNSLOPE OF MORE THAN 5 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 WILL NOT ADVERSELY AFFECT FLOWING STREAMS. DRAINAGE SYSTEMS OR OFFSITE PROPERTIES. 10,ALL STORM SEWER INLETS RECEIVING RUNOFF FROM THE PROJECT DURING CONSTRUCTION SHALL BE PROTECTED SO THAT SEDIMENT-LADEN WATER WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM. 11.ALL OFF-SITE CATCH BASINS IMMEDIATELY ADJACENT TO THE SITE SHALL BE PROTECTED FROM SILTATION. 12. ALL DISTURBED AREAS SHALL BE SEEDED OR SODDED UPON COMPLETION OF WORK. THE CONTRACTOR SHALL BE RESPONSIBLE TO ENSURE THAT COMPLETE COVERAGE OF THE DISTURBED AREAS IS PROVIDED&THAT GROWTH OF THE VEGETATION IS ESTABLISHED. 13. CATCH BASINS SHALL TRAP SEDIMENT OR FILTER FABRIC MUST BE PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED. Geotechnical Testing Laboratory Geotechnical Services 10011 Bw^ gsc.ON FIGURE 5 Qq/QC Services 01"�.wA 98512 GENERAL EROSION Testing Services F�(60))7i54-4 a 12 Not to scale CONTROL NOTES . : , ►T J' N 00'12'32'-f r / 1 ) \ t \\ ,-._ ♦+\/\\`\ \\\ ^\L``-�.. `\ „rl `\� 1 y ✓ {'V 'r -�/\�/ /�,../ \/I\tom I-� I \ '\� lr-\.. j \�,1 ''(� . --�•e. \ \ \_� 1.r Lam• I`I; \\) ^ �•WI\.�\\\_\ y \`\.tom\ \�` �� U) '\ ♦` ...♦.�� �1=��/ �� r..,� ice\ \\.-`����- - �' \� \-_- v/ �. •"� ('�.�. l( �` -\��_i- �\`= ^\\ ��',.,y_ram \\ \ \\ �,� \_\\`♦./\l r l ~\- /// S�� I T, CON \\\.N\ I \ 1 r \:­ \ 1 )I./ NNE �t\ \ 1 �N i`J29'1(2'�,2 - ©.07IN \moll.CA N 1�� .. 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SCALE: - 509 Revisions: Prepared far: SITE PLAN, EROSION Y�11AEL F. p.E,pS OA1 00-0-05 JACK JOHNSON n CONTROL & STORM PLANS „„,o� CHEO(EOBY: MFW P.O. BOX 1119 CQVYASHERVMD CREEK PROPERTY f1ES10N Br: MFw BELFAIR, WA 98528 I JACK JOHNSON ARM,W 0D MiE aeAwH er. zttw (tar.}-sus-s�oo MASON Cf)IINTY WAs10NGTON (360)eoz—xoz (f=)02-1061 (3e0)-275-5400 S CTION'-,?`, TA2N, R1W{ W.M. $ Llne Tablc AIV~ts A L1Aa/L-0 okutlon Stet POW End Point r I / :!:d / ' I , .I :.•� ,• 11^�� \ \ I u 7,w _r wrt o�waxo.a a.�uamo..as :. / 'al/ 1 ^I // ,J IS•I "•, \ I I u er rr tari J Qf or f Mrr 0mumKjmwa1Iu0 aaal>tUaloaU n! _r tan eamm•nomam o..n.�..rn L _rart MMWL a ," FOR CLEARING, EROSION o co co CONTROL & DRAINAGE = x< EAIQRES, SEE SHEET C-1 Oxw Table: Aligrdwta m; a: j Off"/ RadYw LapVl C1+ad Olnctbn startPOWEnd Poht Y m aa. r.a y r art ortam>�s ter�.mI Q a W m I 7 T O g P �?l Ycl PC 3r4287 19 20 PT: 4+38.-2H 1'eanr 8d7a7 06_ s'E - - .$ 239Z •� = Yon pio- 30 9 - - - I pyo riO not w \ € ftr.a s 7/as I R. 3;-7a,7 +\ l � �------------- `EX ACCESS ROAD l l 3 3 3 I f 4 2 2 / � I 1 SA.DR.. 15aoB vc s s' 8 Pit 12+11.08 GRAPHIC SCALE ,Saar vc �' K-& 20532 w 8 P* a+10.32 '� pf NWtI PT. n+u7o � P1/ELEV_ 197.82 HIGH PT.ELEV_ 204.07 d Ka11.443 Di ( in Fur 1,�� $ a te L loos. 100 & p .o (SEE MOTE B) O 2-ASa441T PAM Da 4'CRUFED StFFAC>t16 EEP mo ID -W,SEE MM ER09CN it 113 .0 a)TNC1 M E04E TO COLLECT RROAOIARFACE 1 — R HOM TO STORL TREAnENT FACLMES. .0 e)WW)SOE DITCH TO TRMVCRT WSTIZEM K \ .0 RL44MT SO AS TO B'MASS ROADNAT STORY .0 TREATMENT FAOLSX& J ; .0 ROADWAY 7EME E 0 O .0 HORIZONTAL SCALE: 1 10' .0 VERTICAL SCALE 1' . 2' Cl-- 1 .0 a- CL .0 Nc Z Z W .0 Q.0.0 CLX57M FIN U?)WN GRADE oo 0 z 0+00 1+00 2+00%a'00 4+00 S+OO 6+00 7+00 8+00 9+00 /o+o0 11 .00 12 13+00 14+00 1 1 o0 17 00 1 1 0o PROFILE 'Alignment — (1)' HORZ. 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Dote: PERMIT�: ovol�C im Work order fZequeated by: Numfien Authorized by. �.. Type of Wodtc, -�� Date: �7l�IP(iCn•-7Ccti CHMOE TO: . NAMEAGENCY/COMPANY 131UJNG ADDRE88 PHONE Pub. In chams., tat to o es • arol.ot eart�aaic _. holes Ei'fY11Am MAL ALj E"MEM USM 414 Adud 0i t ; 6AR$: OATS E —� BfSEQ ' ' lza Noun 2 EQUIPMENT USED: Q1t! ! t3lt! 3) BILLED DATE TOTAL ALL M.....�••� PAID-DATE.....,_,�.. Atos—.....r,.....CEGM � . GEOTECHNICAL TESTING LABORATORY The Soil Survey of Mason County, USDA Soil Conservation Service (1960) has mapped the lower(southern) site soils as an Everett gravelly loamy sand, 0 to 5 percent slopes (Ed). The Everett soils are described as very deep, somewhat excessively drained soil on terraces and outwash plains formed in the glacial outwash stage of the most recent Fraser glaciation. These Everett soils coarsen with depth. Permeability is rapid(up to 20 inches per hour) with a high rate of water transmission. These soils are typically classified as "Hydrologic Group A" relative to surficial runoff. The water capacity for plants is low. The soils are further characterized by having medium runoff potential and moderate water erosion potential. Shrink-swell potential is described as low due to the low organic content. The Soil Survey of Mason County, USDA Soil Conservation Service(1960)has mapped the mid slope site soils as an Alderwood gravelly sandy loam, 15 to 30 percent slopes (Ac). The Alderwood soil typically formed from glacial advance outwash. The soil is described as having good natural drainage. Typically,there is no occurrence of a high water table. Internal drainage is described as medium. An erosion hazard may exist if the vegetation is removed: otherwise,the soil has a low erosion hazard in its present condition. Cementation is usually present. Ild ^. Al :wR: `�� 'C• Y .yam, p w �f11 _ 4. l� M .f ..�__,,.._�•-Y�" J(8`p�'.� �� ...,.._ p i Aw The Geologic Map of Washington—Northwest Quadrant(2002)has mapped the northern (upper) site geology as glacial till deposits (Qgt)of continentals 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 Fashon Drift undivided. •l � _ yr '•3 !� ��. .. �h . � -. �y � �J-. < •. ��, i�'� - r�ti ���- , 1 �' it ,'J� '� ..fir... �j..�•-s^�� •. - 'o •f;T _. ,', _ 1001 1 Blomberg Street SW, Olympia, WA 98512 4 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY The Geologic Map of Washington - Northwest Quadrant (2002) has mapped the southern (lower) site geology as advance outwash deposits - (Qga)of continental glacial origin. The report reads: Advance outwash-Glaciofluvial sand and gravel and lacustrine clay, silt, and sand deposited during the advance of glaciers; sandy units commonly thick, well sorted, and fine grained, with interlayered coarser sand, gravel, and cobbles; locally contains - nonglacial sediments and deposits mapped as transitional between glacial and nonglacial. Includes the Colvos and Esperance Sand Members of the Yashon Drift and part of the Yashon Drift undivided. IN- 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 locations. Static groundwater is unknown but presumed deep(-60 feet)at the proposed building locations. SUBSURFACE CONDITIONS In general, undisturbed dense Sinclair shotty loam was observed throughout the proposed building locations. Groundwater seepage was observed along the toe of the slope. Based on the site topography and the nature of the near surface soil, seasonally perched groundwater conditions may be expected during periods of extended wet weather. 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 relief occur on portions of the site, Mason County requires that a geotechnical report be completed according to the Critical Areas Ordinance. The near-surface soils are in a dense to very dense condition except at the ground surface. The surficial soils are generally in a medium dense condition. 10011 Blomberg Street SW,Olympia, WA 98512 5 Phone#: (360)7544612 Fax#: (360)7544848 GEOTECHNICAL TESTING LABORATORY 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. Weathering, erosion, and the resultant sloughing and shallow landsliding are natural processes that can affect steep slope areas. Instability of this nature is typically confined to the upper weathered or disturbed zone, which has been disturbed and has a lower strength. Except for minor ponding, no surface water or active erosion was observed at the proposed building locations. 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. } { ,, , , ; A" is 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 overcome in such a manner as to prevent harm to property and public health and safety, and the project will cause no significant environmental impact. In general,the Vashon glacial till soils observed at the site are 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 structures 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. 10011 Blomberg Street SW,Olympia, WA 98512 6 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 small south-facing slope is in excess of 100 percent and the vertical relief is in excess of 10 feet. Most slopes are approximately 60 percent. 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 northern site area as Class 1. Class 1 is expressed as: Areas believed to be stable. Slopes generally less than 15 percent, but may be greater locally in areas too small to be shown at the map scale. Largely comprises rolling uplands underlain by very stable material such as young glacial till, mantled in places by a thin layer of sandy gravel or other permeable material; also includes flood plains, deltas, alluvial fans, and some beach deposits. Class I areas immediately adjacent to steep slopes of class 3 areas may be threatened by potential landsliding. Normal, proper engineering practices generally are adequate to insure stability in these areas. The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977)describes the lower site area as Class 2. Class 2 is described as, Areas believed to be stable under normal conditions, but may become unstable if disturbed by man's activities, if slope is oversteepened by erosion, or if subjected to strong seismic shaking. Slopes generally steeper than 15 percent, but may be less in some areas of weak geologic materials. Includes areas underlain by. well-drained sand and gravel, mostly on valley sides that lack known slope failures;glacial till with steep slopes;and bedrock. 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') c. Harstine gravelly sandy loam ("Hb') d. Kitsap silt loam("Kc') The central site soils are mapped as Alderwood gravelly sandy loam (Ac). This site does meet the technical criteria of an erosion hazard area. 10011 Blomberg Street SW,Olympia, WA 98512 7 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 its present configuration. The Coastal Zone Atlas, Volume 9, Mason County _ (MA-12) maps the site as Vashon Advance Outwash (Q„a) along the toe of the slope. The chance of flooding is less than one percent. m _8 Permeability is described as high, while runoff potential is low. Infiltration is moderate on natural slopes and high on cut slopes. Springs at the bases o 1 of slopes are common (springs or seeps were observed during the site reconnaissance). The • �` slope stability is described as"intermediate." __— The Coastal Zone Atlas, Volume 9, Mason County (MA-12) maps the site as Vashon glacial till (Q,n) throughout the northern site area. Foundation stability is described as "excellent." Seismic J stability is described as"good." The slope stability \`� is described as"stable." •/ 11 Rocky To prevent minor sliding, uncompacted fill '""'U material and any underlying vegetation shall be o xak 1:24.000 w;k removed in order to construct the foundation. Excavation and backfilling 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. g s: Water in Roadside Ditch from Toe of Slope 10011 Blomberg Street SW,Olympia,WA 98512 g Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural processes that affect slope areas. Significant weathering typically occurs in the upper 2 to 3 feet and is the result of oxidation,root penetration,wet/dry cycles and freeze/thaw cycles. Over excavation may be necessary to ensure the removal of deleterious material. These processes can be managed and the risk reduced through proper construction of the residence. Erosion control recommendations in the slope and buffer areas are provided in the "Building Setback" and "Erosion Control"sections of this report. 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, at building setback will be needed for Setback Setback this tract. A building setback from the crest of the slope to the bottom of the footings should otherwise be- observed. The building setback(see following page)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). An additional building setback of 15 feet will be required from the toe of steep slopes. All foundation elements shall be founded in native material or engineered fill material. For the individual building locations, setbacks for the specific building locations are described below. Peak Shear Stress vs. Normal Stress 2500 2000 370 01 !Z to U) 1500 L N 6- a� ca 1000. Y R N a 1/4 ton 500 f 1/2 ton —t-1 ton 1000 1500 2000 2500 Normal Stress (pso 10011 Blomberg Street SW,Olympia,WA 98512 9 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 (ca = 0.3). Factors of safety were determined using Bishop's, Janbu, and the Morgenstern-Price methods. The glacial material was determined to have a unit weight of 132 pcf, cohesion of 200 psf, and a shear angle (�) of 37°. Under static conditions, the steep slopes (>60 percent) were moderately unstable. Under dynamic loading, the 3328 computations demonstrated that the slopes are susceptible to surficial raveling or deep- seated failure. The following figures illustrate the moment factors of safety for the four slope profiles under the existing conditions. The following figures are the solutions of greatest concern and exhibit the need for a building setback of 30 from the crest of the slopes for building sites 2, 3, 4, 5, 6, and 7. A building setback of 40 feet from the crest of the slope will be required for building site 1. A building setback of 15 feet from the crest of the slope will be required for building sites 8 and 9. Daylight basement designs will not require a building setback from the toe of slopes. Johnson Site -- Site 1 Analysis Method: Morgenstern-Price Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and V�rti al y , •/ •�• 0.96 180 , 160 140 120 .� p 100 Glacial Material (0 80 Unit Weight: 132 N Cohesion: 200 W 60 Phi: 37 40 I, 20 r 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 Distance (ft) 10011 Blomberg Street SW, Olympia, WA 98512 10 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Johnson Site—Site 2 I / • /: •� Analysis Method: Morgenstern-Price ,! • /� Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vedic I R 092 / 180 / . 160 . 140 :\ •/ . 120 Glacial Material p 100 Unit Weight:132 N 80 Cohesion:200 N Phi:37 w 60 40 h 20 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 Distance(ft) . y . Johnson Site—Site 3 Analysis Method: Morgenstern-Price , Direction of Slip Movement: Left to Right / Seismic Coefficient: Horizontal and Vertica • / . . . . . �` 092 .off 220 200 180 �! ' I : % 160 140 p 120 4 Glacial Material > 100 Unit Weight:132 80 Cohesion:200 W Phi:37 60 40 N 20 0 0 50 100 150 200 250 300 350 400 450 500 Distance(ft) 10011 Blomberg Street SW,Olympia, WA 98512 11 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Johnson Site--Site 4 Analysis Method: Morgenstern-Price . 0.87 Direction of Slip Movement: Left to Rigb Seismic Coefficient: Horizontal and V oal 220 . . zoo 180 160 140 00 120 .rl Glacial Material ca> 100 Unit Weight:132 ? 80 Cohesion:200 lL Phi:37 60 40 ` 20 n_ 50 100 150 200 250 300 350 400 450 50, Distance(ft) Johnson Site--Site 5 Analysis Method: Morgenstern- ric Direction of Slip Movement: Le to Right ' Seismic Coefficient: Horizonfa � 'moo •�/• •. '/,• 1 /✓ 20 2000 180 160 140 120 ( > too unityyWaft 132 ? so C hwion:2W W Phi:37 60 40 �1 20 0 0 50 100 150 200 250 300 350 400 450 500 Distance(ft) 10011 Blomberg Street SW, Olympia, WA 98512 12 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Johnson Site -- Site 6 • j` Analysis Method: Morgenstern-Price • • /I • j Direction of Slip Movement: Left to Right :s3 . Seismic Coefficient: Horizontal and Ve I 250 230 �' •• 210 s — 190 = 170 O co 150 Glacial Material W 130 Unit Weight:132 �1 110 Cohesion:200 Phi:37 90 70 0 50 100 150 200 250 300 350 400 450 500 Distance (ft) Johnson Site—Site 7 Analysis Method: Morgenstern-Price d Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vertical By o 220200 180 180 140 p 120 Glacial Material �p 100 Unit Weight 132 y 80 Cohesion:200 W Phi:80 40 20 0 0 50 100 150 200 250 300 350 400 450 500 550 600 850 700 750 Distance(ft) 10011 Blomberg Street SW, Olympia, WA 98512 13 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY Johnson Site -- Site 9 Analysis Method: Morgenstern-Price Direction of Slip Movement: Left to Right Seismic Coefficient: Horizontal and Vertical . . o . . 1 00 220 200 180 160 140 0 120 Glacial Material > 100 Unit Weight: 132 N 80 Cohesion:200 lL Phi:37 60 40 20 0 0 50 100 150 200 250 300 350 400 450 500 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 only observed along the toe of the south-facing slope. Slumping was observed along the toe of the south-facing slope. 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 areas as long as the stumps remain. 10011 Blomberg Street SW, Olympia, WA 98512 14 Phone#: (360) 754-4612 Fax#: (360) 754-4848 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 northern site area as having a very low liquefaction potential. The Liquefaction Susceptibility Map of Mason County, Washington by Palmer, Magsino, Poelstra, Bilderback, Folger,and Niggemann(September 2004)maps the southern 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 '/2-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 not 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. k� 1 y. Toe of Slope - 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 on the slope 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. 10011 Blomberg Street SW,Olympia,WA 98512 15 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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 4. Any re-contouring of the site will create a need for erosion control measures as listed above, see Figure 5. Toe of Slope 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 8 to 14 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. 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. 10011 Blomberg Street SW,Olympia,WA 98512 16 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY 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 7 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. a rf Proposed Building Location �� •J�. 4 .—i'4l. A1 1 � •tee A '•~{ •�• '� got Proposed Building Location 1 10011 Blomberg Street SW,Olympia, WA 98512 1 Phone#: (360)754-4612 Fax#: (360)7544848 ������ � as � �� �.�• � �, �• �-� s Proposed Building • y f Ak *144 e':� may-• Proposed Building Location t� IJ a 1 -•,� x-. '� �*.c' "�.+rr��' �..• r � � ,tip:- � + ' J s. y �` r •�' -n Proposed Building Location 4 39 t '>� , 1�,�•_ r ��1 � � � , ���� ram.-. s Proposed Building 1 1 f �' 'sat 7. •% �D}` z 1"�.�. �Nr 7t.rf' i 7 S s fir' � `� • '�i ' - � - -� ! ; ' `r: �+ > - Proposed Building Location 6 •aa��y4`"'�.: � "q ¢7.a t� � '�•�� - '�� -� �,' \ Ziyj ' � ' � •(i 7+S - I f 'fig F •- '� � �` +�:1.5.�> .yam` ���� �a"� '-_� _� 1�7 i • 1" 1 � 1 ' 1 i • 1 M� i ' 1 1 1 1 : 1 • 1 � , f. f Ci .:w ' /1• 1 6 4 .:I.� �� !�•<� ...Ytl•r M� R e F .s� 5 y,._ - �, ,ai � ���� .r 1 ' • 11 � 1 11 � � ;� ' GEOTECHNICAL TESTING LABORATORY 44 r7Proposed Building Location 9 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 onsite 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 between 5 and 30 percent, the footings should be located a minimum of 2 times the footing width from the slope face (horizontally), and founded in medium dense or denser native soils or properly prepared structural fill. 10011 Blomberg Street SW,Olympia, WA 98512 21 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY r V F A ,t ti. t R ^ Fill Material Along Edge at Proposed Building Locations 6&7 We recommend a minimum width for isolated and continuous wall footings to meet IBC 2003. 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. Active pressure may be determined using an allowable equivalent fluid density of 150 pcf(pounds per cubic foot). We estimate that settlements of footings designed and constructed as recommended will be less than 1 inch, for the anticipated load conditions, with differential settlements between comparably loaded footings of '/z inch or less. Most of the settlements should occur essentially as loads are being applied. However, disturbance of the foundation subgrade during construction could result in larger settlements than predicted. PIN PILES To reduce building setbacks,we suggest that pin piles be utilized to anchor the foundation to the underlying soils. Pin piles are driven into the soil until refusal is achieved. The pin piles are driven with an 80 to 90 pound jackhammer to whatever depth is necessary to reach the specified driving resistance(1 inch or less of penetration for one minute of continuous driving). Standard threaded couplings may be used to connect pipe sections. The pipe sections should be butted together in about the center of the coupling to avoid stripping the threads during driving. If hard driving is anticipated, the ends of the pipe sections can be machined square to provide more surface area for stress transfer during driving. 10011 Blomberg Street SW,Olympia,WA 98512 22 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY The piles are to be driven within the proposed footing. The spacing between piles is to be 3 feet center to center beneath typical structure walls to 1.5 feet center to center for supporting heavier elements such as fireplaces, brick trimmed walls, or to a load of 2000 pounds per 2-inch pile. The piles are installed vertically. Following driving, the piles are cut to length to allow for clearance of the pile cap off the ground. Rebar shall be used as shown on the following diagram. Concrete is then placed within the footing forms surrounding the piles. If pin piles are utilized, building setback distances may be reduced by half or 50 percent. Typical Pin Pile Drawing #3 Rebar Footing Form Footing Form 2 in.min. Pipe Pin Pile #3 Rebar Pipe Pin Pile 2 in.Minimum 10011 Blomberg Street SW, Olympia, WA 98512 23 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. y ice,': i4 � _ . `� ,•y ,/,' 47/ Well-Cemented Glacial Till Found Offsite �. 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 determined using an active pressure coefficient equal to 0.25 (Ka= 0.25). 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 1 H:1 V 75% 61 pcf 10011 Blomberg Street SW,Olympia,WA 98512 24 Phone#:(360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY If the walls are greater than 8 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. 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,with time, can 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. Passive pressure may be determined by using a passive pressure coefficient equal to 4(Kp=4). Factors of safety have been applied to these values. 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 drains should not be connected to the footing drains. 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 southern 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. 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. SEPTIC IMPACT The site will be serviced by the local community sewer system. 10011 Blomberg Street SW, Olympia, WA 98512 25 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY PROPOSED LOGGING Selective logging is proposed throughout the site. Selective tree removal along slopes may occur if one end of the felled tree is elevated when dragging or pulling to the landing area. The underbrush vegetation must remain with minimal disturbance. We expect impacts to slope stability to be negligible. Sediment migration must not leave the site. Additionally, all hazard trees (leaning, rotten, or dead) may be removed to increase slope stability. All logging must be performed by a qualified or licensed logging professional. r _r ' W Y 7 s . I LIMITATIONS We have prepared this report for Jack Johnson 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. 10011 Blomberg Street SW,Olympia, WA 98512 26 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 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. Respectfully submitted, WaBh fo GEOTECIEINICAL TESTING LABORATORY #1XIX /0a"k4 Engineering Geoiogwt : Harold Parks,L.G., L.E.G. 827 \y Senior Engineering Geologist G coo HARO .D PARKS EKP -1- - 31 -No 10011 Blomberg Street SW,Olympia, WA 98512 27 Phone#: (360) 754-4612 Fax#: (360)754-4848 - \ -�� � ► a l ,ice �1))/ - a i 7 i- 2yZ 2 L�1i r , 1 j! rJ ^J �/I /// (./ rr \ t\ ( ( /^� r I\j I ) \ \ - = I = - 1 r _ �/ % = ' Geotechnical „/ \ 1 �' l /: r/ •' ^ s'\—/ C I j • J , ( Testing l l S 8' 3'20" i I \ r Q +120 , \. \ /\ Laboratory PROPOSED t II0y1$__ - / // 1 \ \\ 25' BUILDING 1 PR OSED ry I ^ ) c^ �) LOCA77ON N / �BU DING-- L #01N / ) r ��- PRCPO Z'j �_ 00 // ! // / l ,� P OIpOSEO / \ ' p SED ^/ /J 1 r \`✓\ Cp // BUILD/NC 04, S LT E B M!s-� / i LL// 1 / B LD/NG l / U lNG O1;FAj/ L A7)ON /� /� �_/ ^ B LOINC % 1 / LOCA77ON LL 4J / - j#+ ) I J �/ C\ l �C p(�!I I / \- A AON ILT / F NCE J / /ESILT �_ i -fI /f`7 /i/-\_ r =i- -� J'46"/ I -.� \ - r /�/ // -� � C / 1 r `� � �/ � `••_•' / =`_ 1 � O -A ,-� _i- ,,r J_. �i SILT F N �{ / / \_ t �' A (' _-�i i/ /� 11 ?,r��/ i -_ /j i/�- \ ♦\. \ \ J,{� (-+ \�I / ��/�— �/,�i— \ `� , i CJ1L � r `. -- / / / )/ / i•.r^v��`` _/—��///jam_ \� � r _ r /ri% //// /^ f 11 I / Geotechnical Services l // ///i r -v \ /r` ==i / i���^-—B(/9l / J ,�I / /I/fr////i/JJJi/ /' 111. -\. / // \\ \ \ ///t/-� /I r<J_i/ ' _ r-- ^=iTr=_�i_///i//..•�/i,. _= -�-}1-3gy(p3 T�JY)%r-=��r\..� --`�/.//l.j J%/��� QA/QC Services LOCA /I/ I /1//// Jr Testing Services PQNK77AL IJ Ahj ( I ) + ,\III 'r / / l L7RA770N \ r\� //r/J�JJI�I) ----J !�/ter' ^_- \ � - /-(V ^ LOCA770N /(i 1 I 1 b / r \ // J / ^\ / - SW / y7) C'- )2'-�' 10011 Blomberg St. 1 r Olympia,WA 98512 ,� `( f _-�1%j l//i _= r� (� Phone:(360)754-4612 120. 3 /l l 1��(1/.rld \ __\ ;_- —1_r/%J/ — %�'_-- !/J//� Jt4/\J PO 71AL, Fax:(360)754-4848 S) 44 �I�I -✓j r� ) ^��`\r\ \l+f^ /'- ' /l '� L , < LIV F/L CYAN J - 1J1 w J^� jj '•\ I III / 1 ( + J I I I I _�\ I \ \ \)Il\\\( � .-- / ,- � l ) �`'J '`_� ( � J '- ' +` So - / f `�''� _,=- i ROAD j% + 11 '1 �� i �)�I 11 ),S' -/, `\JJJ Designed/by: M W \ ( \ \ l ( 1 ( \ t N7JAL ' '1 --`��`^�/ \/ \ 1 / Drawn by: ZXW I /< \ \ \ \ 1I 1 / \/ OC ONE %"� // r-- /'��! �r�-�� J,'\\Its �_ ec� Revised by: LL \_)I\ \_\\\^ 1 1 I I I t 1 \ \ �� 1 ^ k / 1 ( - \, , 1 - 9 1 `IJ- r l \ \ + 1 1 v' J / % ti\ Dw # 05-25-05-045 \ . \\ !� + ( ) EEF7 G / / ram_ , \ —I _..` F!\1 ,�STL PROJECT AREA l // / \ (- / f J 1 r•^ � 1 1)/<(� I+ 1 I 1 1 i t � � \/ \ � ^// I J^/ /1 ti J I 11t11 11\ II 1 ( / - r r rri I I I I I\ 11 l 1\t\\ 1 / r /\ % r _ f / f` JfJ ✓� 111 I \ O C I = 1 b± ACRES ) /W % J\1\\1 t \1 i%1 I\I ( � l r' ( I / , ) \ 1\ 1 11 1 ( 1 // /^JI / )\\\\I III\\I 1 \1 I f f / rf'� J` \_/ l 1 1 1 I N / II r \ , sr /tAAE Sawnmtrf Am)9261 - / .f j 1 1 \) I ` y (- \ l AF/Lilwrm FRGw J'(/Lrr Sb(AMD uuR f ++;, I/i r'-_ / r�_�t 1 1\ I 11 11 1 I I a0 r/\j j ) --\\r/ 1 J ) \\\ 11 I+)I 1 1/ )J O /^\ �I 11 /♦ r / 1 f r \\ `\ aulr / --Y �I.J / j J 1 I \\(1 I( ) )I I (t ( I \ r`/ J �/ 1 + + 1s �+ter I \ � / STA PCME.Ng4rH 2GNE NAIO ER I 1 rr f/.)N I// ! i /+/JII J Ill)I r 1 I I \ Z / \ IJ �/` 1 i ! / / 1 \ /"� ^--I � J /" i )l+ + /l( ) 1 / I / / 4 ��PorArm 7D83+IK < \_ r ' \ PROJECT NAME: r� / \ ZX tJOp9LMMA� AW M NGQ IM \ I / \ I )= -� / \�_ ./ \ `\ 1 1 //% 4 / 1 ( I ^�_% / j / --\„/"r `ter\ \ \ 1 / / , /,/ ) / l < l < , f� / )1\l + (r ( l r r r} I . I I I GRAPHIC SCALE / JACKJOHNSON f I( 1 (;)I fJ�II 1 + 1 \\y \r' \ �(y l J Q J r \� \ \ r- / t,` \ KNUDSEN TRACTS ALLYN,WASHINGTON 1 1 \ ;e5 , \ c� �'W, i / , ` ( , % •�, IJ �\ ; i mon- ioo a \\_ r/ I 2597.06=) r ( / Revisions: `ter' 05131/05 \\ , \ t \ )� J \ i t\\\\\ \\ / ' N I 44\16 E F�\ 09/01105 I , r JI ) ( \ \\ \ \ ( 1 f 1 / \ \) \ \I \) I \) t\ 1\ \\ \ \ \\ <I /- \>\\\\\\\\\\\\\\ ) 1 () / ) ��--\� 1 \\ \) ^ A.E. CONSULTANTS I \/ ' I I (I I I / 1 I I / l Y t \� / \ /\ I lll\ \ I� ) \ 3472 NW LOWELL + / /`-` '\/ _/ ' I \ ��^\ ) I I \ ) ` + \\ \ SILVFRDALE WA 98383 /. + / r I I I I / \. \ / 1 \ v N. 1 jra l / / / +� /r / I I ) / J \ \ \ J I / t� \� \\ \ l \ (360)-692-6400 1 �\ r I ,) I r -f� fl\ ,) �rst• , / ` �W, Ir r-" ' (+ + ` I ) / 1 J / I l \ + ___ ♦� SCALE:1 inch=100 feet (14 .5� ; ) ;� FIGURE 2 r 1 j All, SJlr , t ; It ITE PLAN 1/2 INCH MINIMUM DIAMETER STEEL ROD (STRAP)CLAMPED SECURELY TO PIPE CORRUGATED TIGHTLINE 4 INCH M'N/41, \ MINIMUM,6 INCH SUGGESTED '.t.",-_ _ems ..,�;_:a:>. �-e•: '-. TIGHTLINE ANCHORED WITH TWO, 3 FOOT REBAR LENGTHS OR BOLTS. FLARE END SECTION QUARRY SPALL OR ENERGY DISPERSION DEVICE :w- ". ' `a ' • w :�.F^r' 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 Geotedmicai services 10011 k-dwo st sw FIGURE 3 QA/QC Services � .WA 99512 Pt-:"6°7544612 DRAINAGE DETAILS Testing Services Fax:(col 751J818 Not to scale FILTER FABRIC MATERIAL 60"WIDE ROLLS USE STAPLES OR WIRE RING TO ATTACH FABRIC TO WIRE 2"X2"X14 GAUGE WIRE FABRIC OR EQUIVALENT / Q 2'-0" 5 UND SURFACE 2 6 - '..'....i..y....__... _.---._...'............................. ........._.._...._�..a--i....... 6'MAX 2"X4"WOOD POSTS,STANDARD OR BURY BOTTOM OF FILTER BETTER OR EQUAL ALTERNATE: MATERIAL IN 8"X12"TRENCH STEEL FENCE POSTS FILTER FABRIC - 6" 2"X2"X14 GAUGE WIRE --___- FABRIC OR EQUIVALENT - --- - - 2'-p „I GROUND SURFACE 5-0" PROVIDE 314"-1 1/2"WASHED GRAVEL BACKFILL IN TRENCH 12" AND ON BOTH SIDES OF FILTER FENCE FABRIC ON THE SURFACE 8"MIN - --2"X4"WOOD POSTS ALT:STEEL FENCE POSTS FILTER FABRIC FENCE NOTES: 1. FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS. WHEN JOINTS ARE NECESSARY,FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT BOTH ENDS TO THE POST. 2. POSTS SHALL BE SPACED A MAXIMUM OF 6 FEET APART AND DRIVEN SECURELY INTO THE GROUND(MINIMUM OF 30 INCHES). 3. A TRENCH SHALL BE EXCAVATED APPROXIMATELY 8 INCHES WIDE AND 12 INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER. 4. WHEN STANDARD STRENGTH FILTER FABRIC IS USED,A WIRE MESH SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE OF THE POSTS USING HEAVY-DUTY WIRE STAPLES AT LEAST 1 INCH LONG,TIE WIRES OR HOG RINGS. THE WIRE SHALL EXTEND INTO THE TRENCH A MINIMUM OF 4INCHES AND SHALL NOT EXTEND MORE THAN 36 INCHES ABOVE THE ORIGINAL GROUND SURFACE. 5. THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE AND 20 INCHES OF FABRIC SHALL BE EXTENDED INTO THE TRENCH. THE FABRIC SHALL NOT EXTEND MORE THAN 36 INCHES ABOVE THE ORIGINAL GROUND SURFACE- FILTER FABRIC SHALL NOT BE STAPLED TO THE EXISTING TREES. 6. WHEN EXTRA-STRENGTH FILTER FABRIC AND CLOSER POST SPACING IS USED,THE WIRE MESH SUPPORT FENCE MAP BE ELIMINATED,IN SUCH A CASE,THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THE POSTS WITH ALL OTHER PROVISIONS OR ABOVE NOTES APPLYING. 7. FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE UPSLOPE AREA HAS BEEN PERMANENTLY STABILIZED. 8. FILTER FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL. ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY. Geotechnical Testing Laboratory Geotechnical Services toots 81-"*-gs.sw QA/QC Servi any,WA 98512 FIGURE 4 ces Testing Services FF(scol7 iz 544848 Not to scale SILT FENCE DIAGRAM GENERAL EROSION CONTROL NOTES: 1. EROSION CONTROL MEASURES SHALL BE IN PLACE PRIOR TO THE BEGINNING OF CONSTRUCTION. THE PROJECT ENGINEER AND THE COUNTY SHALL INSPECT AND APPROVE THE INSTALLATION OF EROSION CONTROL MEASURES PRIOR TO BEGINNING CONSTRUCTION. 2. EROSION CONTROL MEASURES ARE NOT LIMITED TO THE ITEMS ON THIS PLAN. THE CONTRACTOR IS RESPONSIBLE FOR THE INSTALLATION AND MAINTAINANCE OF ALL EROSION CONTROL MEASURES. NO SILTATION OF EXISTING OR PROPOSED DRAINAGE FACILITIES SHALL BE ALLOWED. CARE SHALL BE TAKEN TO PREVENT MIGRATION OF SILTS TO OFF SITE PROPERTIES. 3 THE CONTRACTOR SHALL MAKE DAILY SURVEILLANCE OF ALL EROSION CONTROL MEASURES AND MAKE ANY NECESSARY REPAIRS OR ADDITIONS TO THE EROSION CONTROL MEASURES. THE CONTRACTOR SHALL PROVIDE ADDITIONAL EROSION CONTROL MEASURES AS DETERMINED NECESSARY BY THE COUNTY INSPECTOR AND/OR THE PROJECT ENGINEER. FAILURE TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL REQUIREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED AGAINST THE CONTRACTOR AND/OR PROJECT OWNER. 4. DURING THE WET SEASON (NOVEMBER TO MARCH)ALL DISTURBED SOILS SHALL BE STABILIZED WITHIN 48 HOURS AFTER STOP OF WORK. EROSION CONTROL MEASURES SHALL INCLUDE, BUT NOT BE LIMITED TO, COVERING THE EFFECTED AREA INCLUDING SPOIL PILES WITH PLASTIC SHEETING,STRAW MATTING, JUTE MATTING, STRAW MULCH, OR WOOD CHIPS. SEEDING OF THE DISTURBED AREAS SHALL TAKE PLACE AS WEATHER PERMITS. 5. ALL SEEDED OR SODDED AREAS SHALL BE CHECKED REGULARLY TO MAKE SURE VEGETATIVE COVERAGE IS COMLETE. AREAS SHALL BE REPAIRED, RESEEDED,AND FERTILIZED AS REQUIRED. 6. TRACKING OF SOIL OFFSITE WILL NOT BE ALLOWED. IF ANY SOIL IS TRACKED ONTO A COUNTY STREET, IT SHALL BE REMOVED BY THE END OF THAT WORKING DAY. ANY FURTHER TRACKING OF MUD WILL THEN BE PREVENTED BY SWEEPING OR WASHING OF THE VEHICLES TIRES BEFORE DRIVING ON A COUNTY STREET. 7. NO MORE THAN 500 LF OF TRENCH ON A DOWNSLOPE OF MORE THAN 5 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 WILL NOT ADVERSELY AFFECT FLOWING STREAMS. DRAINAGE SYSTEMS OR OFFSITE PROPERTIES. 10, ALL STORM SEWER INLETS RECEIVING RUNOFF FROM THE PROJECT DURING CONSTRUCTION SHALL BE PROTECTED SO THAT SEDIMENT-LADEN WATER WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM. 11. ALL OFF-SITE CATCH BASINS IMMEDIATELY ADJACENT TO THE SITE SHALL BE PROTECTED FROM SILTATION. 12.ALL DISTURBED AREAS SHALL BE SEEDED OR SODDED UPON COMPLETION OF WORK. THE CONTRACTOR SHALL BE RESPONSIBLE TO ENSURE THAT COMPLETE COVERAGE OF THE DISTURBED AREAS IS PROVIDED&THAT GROWTH OF THE VEGETATION IS ESTABLISHED. 13. CATCH BASINS SHALL TRAP SEDIMENT OR FILTER FABRIC MUST BE PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED. Geotechnical Testing Laboratory Geotechnical Services +0011 Bl..b.e sl.SW FIGURE 5 QA/QC Services Olrm 'WA 98512 GENERAL EROSION Testing Services F��3co7su 8 Not to scale CONTROL NOTES