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Home My WebLink About964502304 Geotech Assessment GEOTECHNICAL ENGINEERING INVESTIGATION PROPOSED WORK SHOP AND RESIDENTIAL STRUCTURE TAX PARCEL # 964502304 DISCOVERY BAY VILLAGE JEFFERSON COUNTY, WASHINGTON PROJECT NO. 102-01089 January 11, 2002 Prepared for: MR. STEVE FAGER DBVUC INC. P.O. BOX 1921 SEQUIM, WASHINGTON 98382 Prepared by: KRAZAN & ASSOCIATES, INC. GEOTECHNICAL ENGINEERING DIVISION 20714 State Highway 305 NE, Suite 3C Poulsbo, Washington 98370 (360) 598-2126 ~ & ASSOCIATES, INC. GEOTECHNICAL ENGINEERING · ENVIRONMENTAL ENGINEERING CONSTRUCTION TESTING AND INSPECTION & ASSOCIATES, INC. GEOTECHNICAL ENGINEERING · ENVIRONMENTAL ENGINEERING CONSTRUCTION TESTING & INSPECTION January 11, 2002 KA Project No. 102-01089 Mr. Steve Fager DBV~ Inc. P.O. Box 1921 Sequim, Washington 98382 RE: Geotechnical Engineering Investigation Report Proposed Work Shop and Residential Structure Tax Parcel # 964502304 Discovery Bay Village Jefferson County, Washington Dear Mr. Fager: In accordance with your request, we have completed a Geotechnical Engineering Investigation for the referenced site. The results of our investigation are presented in the attached report. This report presents the results of our field exploration, selective laboratory tests, and engineering analyses. If you have any questions or if we can be of further assistance, please do not hesitate to contact our office. Respectfully submitted, KRAZAN AND ASSOCIATES, INC. Shawn E. Williams Senior Geologist WRJ/SEW/wrj Eleven Offices Serving The Western United States 20714 State Highway 305 NE, Suite 3C · Poulsbo, Washington 98370 · (360) 598-2126 · Fax: (360) 598-2127 102-01089 Discovery Bayl 1Dee.doc . .. & ASSOCIATE'S, INC. GEOTECHNICAL ENGINEERING · ENVIRONMENTAL ENGINEERING CONSTRUCTION TESTING & INSPECTION TABLR O¥ CONTENTS INTRODUCTION ............................................................................................................................................................... 1 PURPOSE AND SCOPE ..................................................................................................................................................... 1 PROPOSED CONSTRUCTION ........................................................................................................................................ 2 SITE LOCATION AND SITE DESCRIPTION ..................................... .~ ........................................................................ 3 GEOLOGIC SETTING ...................................................................................................................................................... 3 FIELD AND LABORATORY INVESTIGATIONS ........................................................................................................ 4 SOIL PROFILE AND SUBSURFACE CONDITIONS ................................................................................................... 5 GROUNDWATER ............................................................................................................................................................. 5 SEISMIC CONDITIONS ................................................................................................................................................... 5 SLOPE RECONNAISSANCE AND STABILITY ANALYSIS ...................................................................................... 5 General ............................................................................................................................................................................. 5 Slope Reconnaissance ....................................................................................................................................................... 6 Slope Stability Analysis ..................................................................................................................................................... 6 CONCLUSIONS AND RECOMMENDATIONS ............................................................................................................ 8 General ............................................................................................................................................................................. 8 Site Preparation ................................................................................................................................................................ 9 Foundations .................................................................................................................................................................... 10 Post and Pole Foundation ............................................................................................................................................... 10 Structural Fill .................................................................................................................................................................. 11 Groundwater Influence on Structures/Construction ........................................................................................................ 11 Erosion and Sediment Control ........................................................................................................................................ 11 Drainage and Landscaping .............................................................................................................................................. 12 Floor Slabs and Exterior Flatwork .................................................................................................................................. 12 Testing and Inspection .................................................................................................................................................... 13 LIMITATIONS ................................................................................................................................................................. 13 VICINITY MAP ............................................................................................................................ Figure 1 SITE PLAN ..................................................................................................................................... Figure 2 CROSS-SECTION A-A' ............................................................................................................. Figure 3 PILE CONFIGURATION AND BUILDING SUPPORT ........................................................ Figure 4 Eleven Offices Serving The Western United States 20714 State Highway 305 NE, Suite 3C ° Poulsbo, Washington 98370 · (360) 598-2126 ° Fax: (360) 598-2127 102-01089 Discovery. Bay I 1Dec.doc & ASSOCIATES, INC. GEOTECHNICAL ENGINEERING · ENVIRONMENTAL ENGINEERING CONSTRUCTION TESTING & INSPECTION FIELD AND LABORATORY INVESTIGATIONS ........................................................... Appendix A EARTHWORK SPECIFICATIONS .................................................................................... Appendix B SLOPE STABILITY ANALYSIS ......................................................................................... Appendix C Eleven Offices Serving The Western United States 20714 State Highway 305 NE, Suite 3C · Poulsbo, Washington 98370 · (360) 598-2126 · Fax: (360) 598-2127 102-01089 Discovew Bay I 1 Dee. doc & AS SOCIATE.S, INC. GEOTECHNICAL ENGINEERING · ENVIRONMENTAL ENGINEERING CONSTRUCTION TESTING & INSPECTION January 11, 2002 KA Project No. 102-01089 GEOTECHNICAL ENGINEERING INVESTIGATION PROPOSED WORK SHOP AND RESIDENTIAL STRUCTURE TAX PARCEL # 964502304 DISCOVERY BAY VILLAGE JEFFERSON COUNTY, WASHINGTON INTRODUCTION This report presents the results of our Geotechnical Engineering Investigation for the proposed buildings located at the Nelson Short Plat of Discovery Bay Village, in Jefferson County, Washington. The approximate location of the site is shown on the Vicinity Map, Figure 1. Discussions regarding site conditions are presented herein, together with conclusions and recommendations pertaining to site preparation, slope stability, structural fill, drainage and landscaping, foundations (including timber piles) and concrete floor slabs and exterior flatwork. Presented following the text of this report is a site plan, Figure 2, which shows the approximate exploratory boring locations. A description of the field investigation and exploratory boring logs are presented in Appendix A. Appendix A also contains a description of laboratory testing phase of this study along with laboratory test results. Appendix B contains guides to aid in the development of earthwork specifications. Appendix C contains slope stability analysis results and graphs. When conflicts in the text of the report occur with the general specifications in Appendix B, the recommendations in the text of the report have precedence. PURPOSE AND SCOPE This investigation was conducted to evaluate the present slope, soil, and groundwater conditions at the site and use the surface and subsurface information, obtained during this study, to complete detailed slope stability analyses for the site slopes under static and seismic loading conditions. This investigation was also performed to identify unstable slope areas that may pose a threat to the proposed structures and to provide recommendations for construction of these structures so that any adverse affects on the slope stability will be limited. Our scope of services was performed in accordance with our proposal for this project, dated November 16, 2001 (KA Proposal No. PG01-061 P) and included the following: Eleven Offices Serving The Western United States 20714 State Highway 305 NE, Suite 3C · Poulsbo, Washington 98370 · (360) 598-2126 ° Fax: (360) 598-2127 102-01089 Discovery Bayl 1 Dee.doc KA No. 102-01089 January 11, 2002 Page No. 2 · A site reconnaissance by a member of our engineering staffto evaluate the surface conditions at the project site. · A field investigation consisting of drilling four exploratory borings near and within the footprints of the proposed structures to evaluate the subsurface conditions. The exploratory borings ranged in depth from 9.0 to 21.5 feet below existing grade. · Performing laboratory tests on representative soil samples obtained from the borings to evaluate the physical and index properties of the subsurface soils. · Evaluation of the data obtained from the investigation and performing engineering analyses to develop recommendations for use in the project design and preparation of construction specifications. · Preparation of this report summarizing the findings, conclusions and recommendations of our investigation. PROPOSED CONSTRUCTION We understand that the site may be developed in two phases. The first phase will include the construction of a work shop. The shop will be of post and pole type foundation construction and will include metal sheathing and a slab-on-grade floor. The shop will be a one story structure and the building will have a footprint of 2,000 square feet (40 feet by 52 feet). The project's second phase will include the construction of a one to two story single family residence. The single family home will be of light wood frame construction and the structure will have a footprint of about 1,500 square feet. The final location of the proposed residential structure has not yet been determined. Once this determination has been made, we should be notified so that we can evaluate the conditions with regard to the proximity of the house to the top edge of the lower slope (south side). Additional analyses for slope stability and foundation support may be needed at that time. The buildings will be located on a relatively level section of the site. This level area was developed with a large bench that was created on the existing site slope. We anticipate cuts and fills of 5 feet or less for the site. An ultra block (modular type block) wall of about 4 feet in height is also planned for the site. The ultra block wall will be located at the toe of slope area that is located north of the proposed buildings. In the event that the general development, structural or grading information detailed in this report are inconsistent with the final design, the geotechnical engineer should be notified so that we may update this writing as applicable. At this time plans and specifications have not been provided to Krazan and Associates, Inc. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl 1Dec.do¢ KA No. 102-01089 January 11, 2002 Page No. 3 SITE LOCATION AND SITE DESCRIPTION The site is located at the Nelson Short Plat of the Discovery Bay Village Development, in Jefferson County, Washington. According to the DeLorme Mapping, Topographic Quadrangle Map, Copyright 1992, the property is located in the southeast quadrant of Section 13, Township 29 North, Range 2 West. The topography of the proposed building area is relatively level. Slopes are present to the north, south and east of the level section. These slopes have gradients of up to 50 percent. The slope and building pad areas are represented by Cross-section A-A', Figure 3. The proposed building area has been graded and stripped of vegetation. The slope areas that perimeter the site have been selectively harvested and currently contain mixed canopies of alder, maple, douglas fir and cedar trees as well as black berry briers. The site is surrounded by undeveloped, forested property. An unpaved road provides access to the site. We understand that the level building area was created by benching into the hillside in the early 1980's. Other site improvements include a septic system, slope terraces north of the proposed residence and a system of gabions and quarry spalls, which has been used to help maintain stability in the slope, located down hill of the proposed buildings. GEOLOGIC SETTING The site lies within the central Puget Lowland. The lowland is part of a regional north-south trending trough that extends from southwestern British Columbia to near Eugene, Oregon. North of Olympia, Washington, this lowland is glacially carved, with a depositional and erosional history including at least four separate glacial advances/retreats. The Puget Lowland is bounded to the west by the Olympic Mountains and to the east by the Cascade Range. The lowland is filled with glacial and nonglacial sediments consisting of interbedded gravel, sand, silt, till, and peat lenses. The site and vicinity are in an area that is mapped as Glacial Deposits of the continental ice sheet (Qc). These deposits are described as moraine and stratified deposits consisting of sand, silt, clay, and gravel. (R.W. Tabor and M.W. Cady, 1978) The U.S. Department of Agriculture (USDA) Soil Survey of the Jefferson County Area Map indicates that two soil types are in contact in the general.area of the proposed development (Clallam and Hoypus). Soils encountered during our field investigation appear to be consistent with USDA classifications. Clallam soil is described as well-drained soil that has a very low permeability, a cemented layer at a depth of about 20 to 40 inches and is formed in glacial till under a forest of mixed coniferous and deciduous trees. These soils are typically encountered on glacial terraces, on the breaks of canyons and steep drainage ways. The soil profile typically consists of a thin layer of organic litter at the surface. The upper 3 inches of the soil consists of grayish brown gravelly sandy loam, which is underlain by dark grayish brown gravelly sandy loam, which is approximately 20 inches thick. This is underlain by a Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bay 11Dec.doc KA No. 102-01089 January 11, 2002 Page No. 4 weakly cemented olive-gray gravelly sandy loam. Glacial till is encontered at a depth of about 36 inches. Clallam soil has moderate permeability above the cemented layer and this material has a slight to moderate hazard for water erosion. Hoypus soil is described as somewhat excessively drained, gravelly material, which is formed in glacial outwash on terraces and occurs on glacial outwash terraces where they converge with steep ravines and drainageways. The soil profile typically consists of a 3- inch layer of organic matter. The organic layer is underlain by about 7 inches of dark-gray and dark- brown gravelly loamy sand, which is underlain by dark yellowish-brown gravelly loamy sand, which is approximately 16 inches thick. This is underlain by a dark grayish-brown gravelly loamy sand layer that is approximately 18 inches thick and this layer is in turn underlain by a dark grayish-brown very gravelly sand (approximately 16 inches thick). Hoypus soil has rapid permeability with a slight to moderate hazard for water erosion. The Slope Stability Map of Northeastern Jefferson County, Washington indicates that two types of slopes are in contact in the area of the site (Class 2 and Class 3). Class 2 consists of steep slopes that are believed to be stable, and Class 3 denotes areas of poor natural stability. No large-scale areas of slope instability were observed. FIELD AND LABORATORY INVESTIGATIONS A field investigation consisting of four exploratory soil borings was conducted at this site to evaluate the subsurface conditions. Borings B-1 and B-2 were placed at the location of the proposed workshop, and reached depths of approximately 16.5 and 19.0 feet below existing grade. Boring B-3 was placed at the location of the proposed residential structure and reached a depth of approximately 9.0 feet below existing grade. Boring B-4 was located south of the proposed residential structure, and reached a depth of approximately 21.5 feet below existing grade. Figure 2 shows the approximate locations of the borings. Drilling and sampling work was performed on November 19, 2001. Davies Drilling was used as the drilling subcontractor. A limited access, tracked-drilling rig was used to complete the field exploration work. During drilling operations, penetration tests were performed at regular intervals to evaluate the soil density/consistency and to obtain information regarding the engineering properties of the subsoils. Soil samples were retained for laboratory testing. The soils encountered were continuously examined and visually classified in accordance with the Unified Soil Classification System (USCS). A more detailed description of the field investigation is presented in Appendix A. Laboratory tests were performed on selected soil samples to evaluate their physical characteristics and engineering properties. The laboratory testing program was formulated with an emphasis on the evaluation of natural moisture, gradation and shear stren~h of the materials encountered. Details of the laboratory testing program and the results of the laboratory tests are summarized in Appendix A. This information, along with the field observations, was used to prepare the final boring logs, which are contained in Appendix A. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl 1Dec.doc KA No. 102-01089 January 11, 2002 Page No. 5 SOIL PROFILE AND SUBSURFACE CONDITIONS The subsurface conditions encountered, during this investigation, appeared to be typical of those found in the mapped geologic unit. Our borings revealed that the areas of the proposed shop and single family residence are generally underlain by fill along the slope and the fill appears to taper back into the bench. The fill generally consists of fine grained loose to very dense, silty sand with gravel and this material extended to depths of 5 to 10 feet below existing grade. The moisture content of the fill ranged from approximately 6 to 14 percent. The fill is underlain by dense to very dense silty sand with gravel. The moisture content of the underlying, native soil ranged from approximately 3 to 14 percent. For additional information about the soils encountered, please refer to the logs of the borings in Appendix A. GROUNDWATER Groundwater was not encountered in the exploratory borings. It should be recognized that water table elevations might fluctuate with time, being dependent upon seasonal precipitation, irrigation, land use, and climatic conditions, as well as other factors. Therefore, water level observations at the time of the field investigation may vary from those encountered during the construction phase of the project. The evaluation of such factors is beyond the scope of this report. SEISMIC CONDITIONS According to the Seismic Zone Map of the United States contained in the 1997 Uniform Building Code (UBC), the project site lies within Seismic Risk Zone 3. The soils encountered in the exploratory borings ranged from loose to very dense, with the majority of the soils encountered below a depth of 10 feet being very dense. The overall soil profile generally corresponds to a seismic soil profile of So as defined by Table 16-J of the 1997 Uniform Building Code. A soil profile of Sc generally consists of very dense soil in the upper 100 feet. Due to the dense nature of the majority of the soils encountered during our field exploration and the absence of shallow groundwater, it is our opinion that the risk for liquefaction of the on site soils is very limited. SLOPE RECONNAISSANCE AND STABILITY ANALYSIS General We have performed slope reconnaissance work and stability analyses to evaluate the stability of the relatively steep site slopes. These slopes are about 50 feet high and have gradients of up to 50 to 60 percent. The soils encountered during the subsurface exploration program and observation of exposed soils in slope areas indicate that the slopes are generally comprised of silty sands and gravels that have been moderately to highly compressed. Soil strength parameters used in our analyses were based on in-sim Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bay 11Dec.doc KA No. 102-01089 January 11, 2002 Page No. 6 penetration tests, laboratory stren~h determinations and published values. The methods used in analyzing the site slopes are described in more detail in the following paragraphs. Slope Reconnaissance As part of our field exploration, we conducted a site reconnaissance to observe the surface slope conditions. Our reconnaissance consisted of traversing the site slopes in order to delineate areas of past and potential future slope instability. The slopes were checked for signs of instability. These signs may include indicators such as head scarps, hummocky terrain, vegetation patterns conducive to slope destabilization, tension cracks, surface runoff, and groundwater seepage emanating from the slopes. During our reconnaissance a limited site survey was performed utilizing a Suunto PM-5 Hand Held Inclinometer to estimate slope gradients and a 300-foot long fiberglass tape was used for slope distance measurements. The survey should be considered accurate only to the degree implied and the method used. During our site visit we met with the project general contractor. The contractor showed us the approximate areas for the work shop and the single-family residence. It is our understanding that underground utilites will be provided for the site from the well location below. At the time of our field investigation a small slide was observed south of the proposed shop area with dimensions of about 10 feet by 5 feet. The slide can be attributed in part to the placement of loose fill and it is our opinion that this will not have a significant long-term impact on the proposed structures. The gabion systems that were described in the Site Location and Site Description section of this report, were installed in the 1980's and this area is currently vegetated with an established mixed canopy that is composed primarily of evergreens. The terrace and gabions do not show evidence of instability on the southern and eastern slopes. The northern slope area, above the terrace, is generally vegetated with tall grass and alders, except in the area of the proposed buildings where the cut is near vertical. In this area the vegetation is relatively sparse. Evidence of a small landslide was observed on the western slope area. Slope Stability Analysis Quantitative slope stability analyses were conducted to evaluate the stability of the site slopes and to determine minimum slope setbacks for the structures. We used the PCSTABL7 computer program to model the potential for rotational slope failures. Our slope stability analyses provided us with factors-of- safety against rotational failure. The factor-of-safety is the ratio of the resisting forces to the driving forces (forces tending to cause slope failure). A factor-of-safety of 1.0 is considered equilibrium. A factor-of- safety of less than 1.0 indicates failure and a factor-of-safety of 1.3 is generally considered the acceptable minimum for static conditions. A factor of safety of 1.1, under loading conditions from a design earthquake, is considered acceptable for slope stability analysis under seismic conditions. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl 1Dec.doc KA No. 102-01089 January 11, 2002 Page No. 7 Soil strength parameters derived from information gathered during our field investigation were used to develop the slope cross sections and soil profiles for the stability analyses. For the purposes of our analyses the soil parameters were based on information presented in the Foundation Handbook, H.Y Fang 1991, table 3.38 on Page 138. This table shows the relationship between Standard Penetration Test (SPT) results, relative density, and internal friction for non-cohesive granular soils. The analyses reflect that surface runoff is not allowed to flow over slopes or infiltrate along building areas and charge the slope with subsurface groundwater. To model the effects of a design earthquake a peak horizontal ground acceleration of 0.17g was used. This peak ground acceleration is in general accordance with local municipalities' (including Kitsap County and City of Seattle) design requirements for the type of soil, encountered at the project site. We have presented overall static and seismic global stability in the tables below for Cross Section A-A' (Proposed Work Shop). The final location of the single family home has not been determined. Once the final location is set, additional slope stability analyses for the single family residence may be warranted. In order to determine pile lengths for the proposed shop (it has already been determined that the shop will be founded on piles due to its proximity to the top edge of the lower slope) we used cross sections generated from our subsurface exploration and site reconnaissance. For the purpose of establishing the pile lengths, we analyzed seismic and static conditions. We have presented overall static and seismic global stability results in the table below for each of the Cross Section A-A'. Slope Stability Results for Existing Slope Configuration Factor -of-Safety Factor-of-Safety Comment Observed Required Overall Stability (Static) .95 1.3 Unacceptable Overall Stability (Seismic) Less than 1.0 1.1 Unacceptable Due to the placement of the shop very near the top edge of the lower slope (south side), the analyses indicate factors of safety that are lower than the acceptable minimums for both static and seismic conditions. It is our opinion that the primary threat for slope instability under static conditions would result from saturation of shallow fill soils, which could lead to shallow slope failure. The analyses indicate that slope failure will likely occur under design earthquake conditions. It is our opinion that the proposed pile type foundation system is appropriate to provide the needed stability for the proposed shop. The piles supporting the shop, along the top edge of the lower slope, should extend to a minimum depth of 15 feet below existing grade. Piles within in the remainder of the footprint (within the existing bench area) should extend to a minimum depth of 10 feet below existing grade along the shops centerline and 5 to 10 feet along the north side of the shop. These minimum depths were analyzed to verify that adequate slope stability safety factors were achieved. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl 1Dec.doc KA No. 102-01089 January 11, 2002 Page No. 8 Stability Results of modified Slope Area and Pile Supported Structure (piles 12 feet on center) Factor -of -Safety Factor-of-Safety Comment Observed Required Overall Stability (Static) 1.65 1.3 Acceptable Overall Stability (Seismic) 1.33 1.1 Acceptable The analySes reflect the placement of crushed rock along the upper portion of the slope south of the building to depth of up to 4 feet and 15 feet piles placed along a 12 foot pile spacing. With the piles placed as mentioned and the additional rock placed along the upper portion of the slope acceptable factor of safety under both static and seismic were observed. Spacing and depths requirements utilized to support the shop on piles are shown on Figure 4. It should be noted that even the 12 foot pile spacing does not ensure that the structure will be in a usable condition following a design earthquake. The acceptable factor of safety only implies that the slope should remain adequately stable to permit exiting the building safely. Graphical output for the results of our slope stability analyses are presented in Appendix C. CONCLUSIONS AND RECOMMENDATIONS General Based on the findings of our field and laboratory investigations, the results of our engineering analyses and previous geotechnical experience in the project area, it is our opinion the proposed shop may be constructed as planned. We recommend that the structure be supported on the proposed post and pole type foundation system, which should include piles around the building perimeter and within the interior. No construction of shallow footings would be used with this type of system. Based on our analyses, we recommend a minimum pile length of 15 feet in areas near the edge of the lower slope. In areas located further away from the slope, we recommend a minimum pile length of 10 feet centered along the building and 5 to 10 foot embedment lengths along the buildings north side. We understand the owner is willing assume the risk that the building may be sacrificed in the event of slope failure and it is at the owner's discretion that the slab on grade floor be structurally supported. At present, no shallow foundation system is proposed for the planned shop building. In order to permit construction of the shop, we recommend a minimum setback of 10 feet from the upper slope (north side of the bench area) (see Figure 4). The 15 foot deep piles, along the top edge of the lower slope will provide an adequate foundation to slope setback of about 25 feet (greater than the H/3 recommended by the UBC). Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl 1Dec.doc KA No. 102-01089 January 11, 2002 Page No. 9 We understand that after the shop construction is complete, the second phase of construction will commence. This will include the construction of the single family home. Due to the presence of the undocumented fill and the possible proximity of the proposed residential structure to the top edge of the lower slope, we preliminarily recommend that the house be founded on a deep foundation system. We recommend that the proposed house location be forwarded to us for review, once this information becomes available. The client has stated that this information will be forwarded to our office when it becomes available. At that time, we will perform additional analyses to determine suitable foundation options and design parameters. If a pile type foundation system is used for the single family home and the method of installation is generally the same as that for the shop, it is our opinion that the pile lengths for the house will be on the order of 20 to 25 feet in areas adjacent to the top edge of the lower slope. We recommend that landscaping and vegetation be maintained along the developed portion of the site. Irrigation used in landscaping should be monitored closely to verify that irrigation lines do not leak or rupture. Irrigation timers should also be monitored to ensure that they are functioning correctly. The seepage created by leaky or ruptured irrigation lines or faulty irrigation timers may increase surface runoff over slopes, potentially causing slope failures. The following paragraphs present recommendations for the design and construction of the proposed shop building. Site Preparation Site clearing should be limited to the building pad area. General stripping of the building area should include removal of vegetation; trees and associated root systems; wood; rubble; and rubbish. The stripping should extend to a minimum depth of 4 inches, or until all organics in excess of 3 percent by volume are removed. Deeper stripping may be required in localized areas. These materials will not be suitable for use as fill for parking or building areas. However, stripped topsoil may be stockpiled and reused in landscape or non-structural areas. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl lDec.doc KA No. 102-01089 January 11, 2002 Page No. 10 Any buried structures encountered during construction should be properly removed and backfilled. Excavations, depressions, or soft and pliant areas extending below planned finish subgrade level should be cleaned to firm undisturbed soil, and backfilled with structural fill to planned finish subgrade. In general, any septic tanks, underground storage tanks, debris pits, cesspools, or similar structures should be entirely removed. Concrete footings should be removed to an equivalent depth of at least 3 feet below proposed footing elevations or as recommended by the Geotechnical engineer. The resulting excavations should be backfilled with structural fill to planned finish subgrade. During wet weather conditions, typically October through May, subgrade stability problems and grading difficulties may develop due to excess moisture conditions, disturbance of sensitive soils and/or the presence of perched groundwater. Construction during the extended wet weather periods could create the need to overexcavate exposed soils if they become disturbed and cannot be recompacted due to elevated moisture content and/or weather conditions. If overexcavation is necessary, it should be confirmed through continuous monitoring and testing by a qualified geotechnical engineering firm. Soils that have become unstable may require drying and recompaction. Selective drying may be accomplished by scarifying or windrowing surficial material during extended periods of dry, warm weather. If the soils cannot be dried back to a workable moisture condition, remedial measures may be required. General project site winterization should consist of the placement of aggregate base and protection of exposed soils during the construction phase. A representative of our firm should be present during all site clearing and grading operations to test and observe earthwork construction. This testing and observation is an integral part of our service as acceptance of earthwork construction is dependent upon compaction of the material and the stability of the material. The geotechnical engineer may reject any material that does not meet compaction and stability requirements. Further recommendations of this report are predicated upon the assumption that earthwork construction will conform to recommendations set forth in this section and the Structural fill section. Foundations Post and Pole Foundation We understand that the shop will be founded on a post and pole type system, with the poles spaced at about 12 feet on center. The pile foundation system will consist of pressure treated wood poles. The poles will provide support to the shop in the event of slope instability along the south side of the shop. The poles that will be used for this application may consist of air-dried Douglas fir or similar tree species, which are treated with creosote or other wood preservatives. The placement of the piles will consist of augering holes, placing the treated poles and backfilling the augered holes with concrete. As stated in the Slope Stability Analysis section of this report, we recommend a minimum pile length of 15 feet for areas located along the top edge of the lower slope. In areas north of the slope, a minimum pile length of 5 to 10 feet may be suitable. For further clarification of pile lengths, please see Figure 4. We recommend that the poles be monitored, periodically, for rot, and if necessary the poles should be treated with additional wood preservative to extend their life. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discove~ Bay I 1Dec. doc KA No. 102-01089 January 11, 2002 Page No. 11 If constructed as recommended, the total settlement is not expected to exceed 1 inch. Differential settlement, along a 20-foot exterior wall, or between adjoining columns, should be less than ½ inch, producing an angular distortion of 0.002. Most settlement is expected to occur during construction, as the loads are applied. Structural Fill On-site soils may be suitable for reuse as structural fill provided they are relatively free from organic material and debris. We recommend that a representative of Krazan & Associates be on-site during excavation to determine which soils are suitable for structural fill. Imported Structural fill material should consist of well graded gravel or a sand and gravel mixture with a maximum grain size of 1 ½ inches and less than 5 percent fines (material passing the No. 200 sieve). All Structural fill material should be submitted for approval to the geotechnical engineer at least 48 hours prior to delivery to the site. Fill soils should be placed in lifts approximately 6 to 8 inches thick, moisture-conditioned as necessary, (moisture content of soil shall not vary by more than 4-2 percent of optimum moisture) and compacted to 95 percent of the maximum density based on ASTM Test Method D1557. Additional lifts should not be placed if the previous lift did not meet the required dry density or if soil conditions are not stable. Groundwater Influence on Structures/Construction Groundwater was not encountered in the exploratory borings. It should be recognized that water table elevations may fluctuate with time, being dependent upon seasonal precipitation, irrigation, land use, and climatic conditions, as well as other factors. Therefore, water level observations at the time of the field investigation may vary from those encountered during the construction phase of the project. If groundwater is encountered during construction, a qualified geotechnical engineering firm should be consulted prior to dewatering the site. Although groundwater is not anticipated at the proposed building subgrade areas, there is a possibility that perched groundwater may be present within the zone of structural influence or affect the construction of foundations. Erosion and Sediment Control Erosion and sediment control (ESC) is used to minimize the transportation of sediment to wetlands, streams, lakes, drainage systems, and adjacent properties. Erosion and sediment control measures should be taken and these measures should be in general accordance with local regulations. As a minimum, the following basic recommendations should be incorporated in the design of the erosion and sediment control features of the site: 1) Phase the soil, foundation, utility, and other work, requiring excavation or the disturbance of the site soils, to take place during the dry season (generally May through September). However, Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl 1Dee.doc KA No. 102-01089 January 11, 2002 Page No. 12 provided precautions are taken using Best Management Practices (BMP's), grading activities can be undertaken during the wet season (generally October through April). 2) All site work should be completed and stabilized as quickly as possible. 3) Additional perimeter erosion and sediment control features may be required to reduce the possibility of sediment entering the surface water. This may include additional silt fences, silt fences with a higher Apparent Opening Size (AOS), construction of a berm, or other filtration systems. 4) Any runoff generated by dewatering discharge should be treated through construction of a sediment trap if there is sufficient space. If space is limited other filtration methods will need to be incorporated. Drainage and Landscapin~ The ground surface should slope away from building pad and pavement areas toward appropriate drop inlets or other surface drainage devices. It is recommended that adjacent exterior grades be sloped a minimum of 2 percent for a minimum distance of 5 feet away from structures. Roof drains should be tightlined away from foundations and slope. Subgrade soils in pavement areas should be sloped a minimum of 1 percent and drainage gradients maintained to carry all surface water to collection facilities and off-site. These grades should be maintained for the life of the project. Floor Slabs and Exterior Flatwork In areas where it is desired to reduce floor dampness, such as areas covered with moisture sensitive floor coverings, we recommend that concrete slab-on-grade floors should be underlain by water vapor retarder system. The water vapor retarder system should be installed in accordance with ASTM Specification E164-94 and Standard Specifications E1745-97. According to ASTM Guidelines, the water vapor retarder should consist of a vapor retarder sheeting underlain by a minimum of 4-inches of compacted clean, open-graded coarse rock of ¼-inch maximum size. The vapor retarded sheeting should be protected from puncture damage with a minimum of 2-inches of sand. The sand should be well moistened prior to placement of the concrete slab. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bay I 1 Dee.doc KANo. 102-01089 January ll, 2002 Page No. 13 Testing and Inspection A representative of Krazan & Associates, Inc. should be present at the site during the earthwork activities to confirm that actual subsurface conditions are consistent with the exploratory fieldwork. This activity is an integral part of our services as acceptance of earthwork construction is dependent upon compaction testing and stability of the material. This representative can also verify that the intent of these recommendations is incorporated into the project design and construction. Krazan & Associates, Inc. will not be responsible for grades or staking, since this is the responsibility of the Prime Contractor. LIMITATIONS Geotechnical engineering is one of the newest divisions of Civil Engineering. This branch of Civil Engineering is constantly improving as new technologies and understanding of earth sciences improves. Although your site was analyzed using the most appropriate current techniques and methods, undoubtedly there will be substantial future improvements in this branch of engineering. In addition to improvements in the field of Geotechnical engineering, physical changes in the site either due to excavation or fill placement, new agency regulations or possible changes in the proposed structure after the time of completion of the soils report may require the soils report to be professionally reviewed. In light of this, the Owner should be aware that there is a practical limit to the usefulness of this report without critical review. Although the time limit for this review is strictly arbitrary, it is suggested that two years be considered a reasonable time for the usefulness of this report. Foundation and earthwork construction is characterized by the presence of a calculated risk that soil and groundwater conditions have been fully revealed by the original foundation investigation. This risk is derived from the practical necessity of basing interpretations and design conclusions on limited sampling of the earth. The recommendations made in this report are based on the assumption that soil conditions do not vary significantly from those disclosed during our field investigation. If any variations or undesirable conditions are encountered during construction, the geotechnical engineer should be notified so that supplemental recommendations can be made. The conclusions of this report are based on the information provided regarding the proposed construction. If the proposed construction is relocated or redesigned, the conclusions in this report may not be valid. The geotechnical engineer should be notified of any changes so the recommendations can be reviewed and reevaluated. This report is a geotechnical engineering investigation with the purpose of evaluating the soil conditions in terms of foundation design. The scope of our services did not include any environmental site assessment for the presence or absence of hazardous and/or toxic materials in the soil, groundwater or atmosphere, or the presence of wetlands. Any statements, or absence of statements, in this report or on any boring log regarding odors, unusual or suspicious items, or conditions observed are strictly for Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discove~ Bay l 1Dec.doc KA No. 102-01089 January 11, 2002 Page No. 14 descriptive purposed and are not intended to convey engineering judgment regarding potential hazardous and/or toxic assessment. The geotechnical information presented herein is based upon professional interpretation utilizing standard engineering practices and a degree of conservatism deemed proper for this project. It is not warranted that such information and interpretation cannot be superseded by future geotechnical developments. We emphasize that this report is valid for this project as outlined above, and should not be used for any other site. If you have any questions, or if we may be of further assistance, please do not hesitate to contact our office at (360) 598-2126. Respectfully submitted, KRAZAN & ASSOCIATES, INC. Wesley R. Johnson ' Sean L. tCara' y, . . Staff Engineer Engineering Manager WRJ/SLC.wrj . , . . Krazan & Associates, Inc. Eleven Offices Serving Thc Western United States 102-01089 Discovery Bay.wrj.doc Discovery Bay .'..'. : .:::!~ -. :..~' qlt 'Point . ,. Piles ~ ,.. :.~.." II 5' . ~ :. ~,~.:. · .:~.: ..::.--- , :..., :'." ." /.:.' .::.. .. . . h.~"; ,.? ' . ' ..: .. · .-. - ,\,,~ -· .. /" ~' ':': SITE ~ \ ** · '--~..~ / /-\~ Note: from Port Townsend South, WA. USGS ~adran~le dated 1953, photorevised 1981. . FIGURE I-SITE VICINITY MAP KRAZAN & ASSOCIATES, INC. 20714 State Route 305-Suite 3C Project Name: Discovery Bay SFR Poulsbo, WA 98370 Location: Jefferson County, Washington 360-598-2126 Job No.: 102-01089 ~ Client: Mr. Steve Fager Date: 11/29/01 Je§e_-I e^els ~q pep!^cud uo!letuJo~u! uo peses s6u.~eJQ :eloN Appendix A Page A. 1 APPENDIX A FIELD AND LABORATORY INVESTIGATIONS Field Investigation The field investigation consisted of a surface reconnaissance and a subsurface exploratory program. Four exploratory borings were drilled. The soils encountered were logged in the field during the exploration and, with supplementary laboratory test data, are .described in accordance with the Unified Soil Classification System. The exploratory boring locations are shown on the Site Plan, Figure 2. Topographic information was supplemented by provided information and used to estimate boring and elevations. The depths shown on the attached boring logs are from the existing ground surface at the time of our subsurface exploration. The drilled borings were advanced using a limited access track-mounted Davies II drill rig. Disturbed soil samples were obtained by using the Standard Penetration Test (SPT) as described in ASTM:D- 1586. The Standard Penetration Test and sampling method consists of driving a standard 2-inch outside-diameter, split barrel sampler into the subsoil with a 140-pound hammer free falling a vertical distance of 30 inches. The summation of hammer-blows required to drive the sampler the final 12- inches of an 18-inch sample interval is defined as the Standard Penetration Resistance, or N-value. The blow count is presented in the boring logs in this appendix. The resistance, or "N" value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils. The soils encountered were logged in the field during the exploration and, with supplementary laboratory test data, are described in accordance with the Unified Soil Classification System. All samples were returned to our Poulsbo laboratory for evaluation. Laboratory Investigation The laboratory investigation was designed to determine the physical and mechanical properties of the foundation soil underlying the site. Test results were used as criteria for determining the engineering suitability of the surface and subsurface materials encountered. In situ moisture contents and sieve analysis tests were completed for the samples representative of the subsurface material. These tests, supplemented by visual observation, comprised the basis for our evaluation. The logs of the exploratory borings and laboratory determinations are presented in this appendix. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl ID¢¢.doc ApPendix A Page A.2 WinLoG Symbol Legend ,-:, · o~ Well Graded Gravels, ~..i':...'..,:.i Gravel-Sand Mixtures. Littl Gravel.~qand Mixtures, LitU~ Gravel~qand-Silt Mixtures Gravel-Sand-Clay Mixtures ili!:~!.:'..} ,!J Grave~lyWe~lm,~..Gradedsands,Sands'Little or No~i[!~i~.~.~' ~' ........ - Gravellymn,,.P°°rlY Gradedsands,Sands,Little or No~I~ ~;i~"~ MixturesSilty Sands, Sand-Silt ~ MixturesClayey Sands, Sand-Clay !~ Inorganic Silts and Very ~ Inorganic Clays of Low to ~ Organic Silts and Organic ~ Inorganic Silts, Micaceousor ~ Inorganic Clays of High ~ Organic Clays of Medium t~,-~ Peat, Humus, Swamp and I ! i PlastiCty, Fat Clays High Ptasfid~, Organic i~ OVer Highly Organic Soils Well Symbols Pipes and Screens ~ I I Top ~iffiings ,~ ~None~oN~ ~ ~Cap ~ ~ush~ount Cap ~ Abov~round Cap Boffom Fi~lngs Packing and Bac~li ;NCNE' ~None ~ Bentonite ~Clay i~ ',Silt Cement Sand ~ Sand and Gmv~ ," ' ' Grovel Samole Symbols Split Spoon ~ Auger ~ Core ~ Grab ~ Shelby Tube ~ Excavation Undistumed ~ No Recovery Log of Boring B-t Project No: 102-01089 Project: Discovery Bay SFR Client: Mr. Steve Fager Figure No.: A-1 Location: Sequim, WA Logged By: D.H. Depth to Water: Not Encountered Elevation' SUBSURFACE PROFILE SAMPLE v , ~' Description ~ ~ ,e ~ ~" Water Content (%) ~ o =: .~ o~ ~ > o ] Ground Surface Ve~dense, fine grained sand, gray, moist. ' ' ; ~ ~ ~ · ; S-1 11.1 1.0 SS 65:11.5" ' ~ ~ ; , ~ ,,.n,.,~ (NATIVE)~ ~ ~ .. ,Ve~ dense, fine grained sand, gray, moist. S-2 4.8 0.9 SS 74:11" S-3 6.2 0.3 SS 50:3" Ve~dense, fine grained sand, gray, moist. S~ 5.7 0.6 SS 76:7.5" : ~ ; . . S-5 6.5 0.5 SS 50:6" , : . End ofBoring 20, Groundwater not encountered. . ~ : ~ Method' 3.25 I.D. Track Auger Krazan and Associates Drill Date: 11/19/01 20714 State Highway 305 N,E. Driller: Davies Drilling Suite 30 Sample Method: SPT Operator: Jeff Davies Poulsbo, Washington 98370 Sheet: 1 of 1 Log of Boring B-2 Project No: 102-01089 Project: Discovery Bay SFR Client: Mr. Steve FaDer Figure No.: A-2 Location: Sequim, WA Logged By: D.H. Depth to Water: Not Encountered Elevation: SUBSURFACE PROFILE SAMPLE ~ coz' :~ ~ ~ ~ 5 15 25 35 v I I. I I I ~ I ] Ground Surface ~[~ Loose, fine grained sand, brown, damp, scattered gravel. S-1 7.~ 1.1 SS 7 ~1 SILTY SAND (SM) ................... , .~ Medium dense, fine grained sand, light brown, S-2 6.3 1.0 SS 20 damp to moist, increased gravel. S-3 5.5 1.0 SS 53 : 1~ ~1[U~1~ ~Becomes ve.ry dense: . ~ecomes moist to wet. S-4 7.2 0.6 SS 89:10 .... ; ' : · · ~v~ ~' ~7~7~;:~-~-R'A'V-E ' ~-~7~7~-S' 7~ '~ ' .......... i.~ ~ AND SAND (GW-GM) Very dense, brown, moist. S-5 11.8 0.5 SS 68:11.5"/ i --; .~___ ! ;0°;J WELL GRADED GRA VEL. WITH SAND (GW) : ':{!;IVery dense, brown, damp. S-6 2.9 .5 SS 50:6" 20 End of Boring , Groundwater not encountered. ~ i . : Method: 3.25 I.D. Track Auger Krazan and Associates Drill Date: 11/19/01 20714 State Highway 305 Driller: Davies Drilling Suite 3C Sample Method: SPT Operator: Jeff Davies Poulsbo, Washington 98370 Sheet: 1 of 1 Project: Discovery Bay SFR Log of Boring B-3 Project No: 102-01089 Client: Mr. Steve Fager Figure No.: A-3 Location' Sequim, WA Logged By: D.H. Depth to Water: Not Encountered Elevation: SUBSURFACE PROFILE SAMPLE Description _.e ~ ~ ;Z" *" Water Content (%) o: ~z ~ ~,~ ~, ±~ 5 15 25 35 -..-.- I I ~ I I I I Ground Surface $1L TY SAND (SM) Medium dense, fine grained sand, gray, moist to wet. Scattered gravel. S-1 10.4 1.2 SS 16 . Becomes very dense. S-2 10.1 1.5 SS 73 S-3 9.3 1.2 SS 70 End of Boring ~, '. Groundwater not encountered. : , ! ,. , i ' ' , Method: 3.25 I.D. Track Auger Krazan and Associates Drill Date: 11/19/01 20714 State Highway 305 N.E. Driller: Davies Drilling Suite 3C Sample Method: SPT Operator: Jeff Davies Poulsbo, Washington 98370 Sheet: 1 of 1 Log of Boring B-4 Project No: 102-01089 Project: Discovery Bay SFR Client: Mr. Steve Fager Figure No.: A-4 Location: Sequim, WA Logged By: D.H. Depth to Water: Not Encountered Elevation: SUBSURFACE PROFILE SAMPLE v . ~' Description · $ ~ ~" - Water Content ~ = ~ ~ -- 5 15 25 35 I Ground Su~ace ~1 ~ SILTYSAND (SM) ~ Loose, fine grained sand, brown, wet. Scaffered gravel. S-1 14.4 0.3 SS 6 S-2 12.9 1.2 SS 8 ered . ~ ~'k~l::¢':':':: ................................ ~OORL S-3 12.0 1.2 SS 19 ~ Medium de~se, fine to medium grained sand, gray, ~ ~~ampt°m°lst: J 8-4 9.0 1.5 SS 25 ........... ~$~ ............. Medium dense, fine grained sand, gray, moist. / . ............................... 4~1 v~ dense, r~n~ grained sand, brown to gray, damp S-5 8.7 1.5 S8 85 ~! i. ~ . . moist. Trace of gravel. ~1 ~;~~- ..................... ~ ~ : ~J~ Ve~ dense, fine grained sand, gray, damp to moist. race of gravel. S-6 9.4 1.5 SS 58 ~ ~ ~ ~ ~ End of Boring ~ ~ ~ : 25, Groundwater not encountered. Method: 3.25 I.D. Track Auger Krazan and Associates Drill Date: 11/19/01 20714 State Highway 305 N.E. Driller: Davies Drilling Suite 3C Sample Method: SPT Operator: Jeff Davies Pouisbo, Washington 98370 Sheet: 1 of 1 Appendix B Page B. 1 APPENDIX B EARTHWORK SPECIFICATIONS GENERAL When the text of the report conflicts with the general specifications in this appendix, the recommendations in the report have precedence. SCOPE OF WORK: These specifications and applicable plans pertain to and include all earthwork associated with the site rough grading, including but not limited to the furnishing of all labor, tools, and equipment necessary for site clearing and grubbing, stripping, preparation of foundation materials for receiving fill, excavation, processing, placement and compaction of fill and backfill materials to the lines and grades shown on the project grading plans, and disposal of excess materials. PERFORMANCE: The Contractor shall be responsible for the satisfactory completion of all earthwork in accordance with the project plans and specifications. This work shall be inspected and tested by a representative of Krazan and Associates, Inc., hereinafter known as the Geotechnical Engineer and/or Testing Agency. Attainment of design grades when achieved shall be certified to by the project Civil Engineer. Both the Geotechnical Engineer and Civil Engineer are the Owner's representatives. If the contractor should fail to meet the technical or design requirements embodied in this document and on the applicable plans, he shall make the necessary readjustments until all work is deemed satisfactory as determined by both the Geotechnical Engineer and Civil Engineer. No deviation from these specifications shall be made except upon written approval of the Geotechnical Engineer, Civil Engineer or project Architect. No earthwork shall be performed without the physical presence or approval of the Geotechnical Engineer. The Contractor shall notify the Geotechnical Engineer at least 2 working days prior to the commencement of any aspect of the site earthwork. The Contractor agrees that he shall assume sole and complete responsibility for job site conditions during the course of construction of this project, including safety of all persons and property; that this requirement shall apply continuously and not be limited to normal working hours; and that the Contractor shall defend, indemnify and hold the Owner and the Engineers harmless from any and all liability, real or alleged, in connection with the performance of work on this project, except for liability arising from the sole negligence of the Owner of the Engineers. TECHNICAL REQUIREMENTS: All compacted materials shall be densified to a density not less than 95 percent of maximum dry density as determined by ASTM Test Method D1557 as specified in the technical portion of the Geotechnical Engineer. The results of these tests and compliance with these specifications shall be the basis upon which satisfactory completion of work will be judged by the Geotechnical Engineer. SOIL AND FOUNDATION CONDITIONS: The Contractor is presUmed to have visited the site and to have familiarized himself with existing site conditions and the contents of the data presented in the soil report. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bay I 1 Dee.doc Appendix B Page B.2 The Contractor shall make his own interpretation of the data contained in said report, and the Contractor shall not be relieved of liability under the contractor for any loss sustained as a result of any variance between conditions indicated by or deduced from said report and the actual conditions encountered during the progress of the work. DUST CONTROL: The work includes dust control as required for the alleviation or prevention of any dust nuisance on or about the site or the borrow area, or off-site if caused by the Contractor's operation either during the performance of the earthwork or resulting from the conditions in which the Contractor leaves the site. The Contractor shall assume all liability, including Court costs of codefendants, for all claims related to dust or windblown materials attributable to his work. SITE PREPARATION Site preparation shall consist of site clearing and grubbing and preparations of foundation materials for receiving fill. CLEARING AND GRUBBING: The Contractor shall accept the site in this present condition and shall demolish and/or remove from the area of designated project, earthwork all structures, both surface and subsurface, trees, brush, roots, debris, organic matter, and all other matter determined by the Geotechnical Engineer to be deleterious. Such materials shall become the property of the Contractor and shall be removed from the site. Tree root systems in proposed building areas should be removed to a minimum depth of 3 feet and to such a extent which would permit removal of all roots larger than 1 inch. Tree root removed in parking areas may be limited to the upper 1 ½ feet of the ground surface. Backfill or tree root excavation should not be permitted until all exposed surfaces have been inspected and the Geotechnical Engineer is present for the proper control of backfill placement and compaction. Burning in areas, which are to receive fill materials, shall not be permitted. SUBGRADE PREPARATION: Surfaces to receive Structural fill shall be prepared as outlined above, excavated/scarified to a depth of 12 inches, moisture-conditioned as necessary, and compacted to 95 percent compaction. Loose and/or areas of disturbed soils shall be moisture conditioned and compacted to 95 percent compaction. All ruts, hummocks, or other uneven surface features shall be removed by surface grading prior to placement of any fill material. All areas which are to receive fill materials, shall be approved by the Geotechnical Engineer prior to the placement of any of the fill material. EXCAVATION: All excavation shall be accomplished to the tolerance normally defined by the Civil Engineer as shown on the project grading plans. All over excavation below the grades specified shall be backfilled at the Contractor's expense and shall be compacted in accordance with the applicable technical requirements. FILL AND BACKFILL MATERIAL: No material shall be moved or compacted without the presence of the Geotechnical Engineer. Material from the required site excavation may be utilized for construction site fills provided prior approval is given by the Geotechnical Engineer. All materials utilized for constructing site fills shall be free from vegetable or other deleterious matter as determined by the Geotechnical Engineer. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl 1Dec.doc Appendix B Page B.3 PLACEMENT, SPREADING AND COMPACTION: The placement and spreading of approved fill materials and the processing and compaction of approved fill and native materials shall be the responsibility of the Contractor. However, compaction of fill materials by flooding, ponding, or jetting shall not be permitted unless specifically approved by local code, as well as the Geotechnical Engineer. Both cut and fill shall be surface compacted to the satisfaction of the Geotechnical Engineer prior to final acceptance. SEASONAL LIMITS: No fill material shall be placed, spread, or rolled while it is frozen or thawing or during unfavorable wet weather conditions. When the work is interrupted by heavy rains, fill operations shall not be resumed until the Geotechnical Engineer indicates that the moisture content and desity of previously place fill are as specified. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discovery Bayl lDec.doc Appendix C Page C. 1 APPENDIX C SLOPE STABILITY ANALYSIS GENERAL The slope stability computer program (PCSTABL7) was used to evaluate the global stability of the existing slopes under static and seismic conditions. This FORTRAN based computer program calculates factors of safety for potential slope failures and generates the potential rotational failure planes. The stability of each configuration was analyzed by comparing observed factors of safety to minimum values as set by standard geotechnical practice. A factor of safety of 1.0 is considered as equilibrium and less than 1.0 is considered failure. The recommended minimum factor of safety for global stability is 1.3 for static conditions. For the slope stability analysis under seismic conditions we used a horizontal peak ground acceleration of 0.17g. The horizontal peak acceleration is per 1997 UBC, Table 16-I, Seismic Zone 3, and other city and county agencies in the Puget Sound area which is defined as the ground acceleration with a 10 percent probability of being exceeded in 50 years (i.e. return period of 475 years.) for a 6.6 Maximum Magnitude Seismic Event. Graphical presentations of the slope stability analyses are presented in this appendix. Krazan & Associates, Inc. Eleven Offices Serving The Western United States 102-01089 Discover3,. Bayl 1De~.do¢