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jonesgeo1.pdfE®M ®s-26 Kxazan& ASSOC I ATE S, INC. GEOTE L ENGINEERING • ENVIRONMENTAL ENGINEERING p S R STING & INSPECTION tng�t�L May 12, 2006 MAY 2 6 2Q06 EECE Mr. John Jones C/O Mr. Rick Jones Galeed, Inc. 21420 — 67`h Avenue West, Suite B Lynnwood, Washington 98036 RE: LIMITED GEOTECHNICAL ENGINEERING 7:e Proposed Single Family Residence Parcel No. 00434209002900 Edmonds, WashingtonDear Mr. Jones:C� KA Project No. 092-06078 MAY 19 CITYrT CSEFili10ES CTR, EFY CF EDPIPONDS This letter report presents the results of our Limite eotechnical Engineering Investigation for the proposed single-family residences at the referenced site. The scope of this study was outlined in our Revised Proposal No. G06-066WAW, dated May 8, 2006, and the fieldwork portion of the study was undertaken on May 8, 2006. Site Conditions The site is located at 71X Alder Street in Edmonds, Washington. The general location of the property is shown on the Vicinity Map (Figure 1). The subject property is currently undeveloped and vegetated with grasses, brush and shrubs along the south side of the site. The site generally slopes downward to the west at magnitudes of up to approximately 30 percent. The site contains a two -tiered timber retaining wall system that is approximately 6 feet tall and decreases in elevation from east to west. Proposed Construction The project details are still preliminary at this time. We anticipate that the residential structure will be wood framed with a slab -on -grade garage. We anticipate that the residential structure will be founded on shallow spread footings. Footing loads are expected to be light. We have not yet received a grading plan for the project. Preliminarily, we anticipate maximum cut and fill depths on the order of approximately 4 feet or less. In the event that the structural or grading information detailed in this report is inconsistent with the final design, the geotechnical engineer should be notified so that we may update this writing as applicable. Field Investigation A limited field investigation consisting of three exploratory hand auger borings, which ranged in depth from approximately 2.5 to 4.0 feet below the existing site grades, was completed for shallow subsurface exploration. A Krazan & Associates staff geologist completed the hand auger borings. The holes were excavated by manually Ten Offices Serving The Western United States 19501 144th Ave. NE, #F-300; Woodinville, WA 98072 • (425) 485-5519; Fax (425)485-6837 KA No. 092-06078 May 12, 2006 Page No. 2 of 12 advancing a metal rod hand auger with a bucket type bit. The metal rods were pin connected and the hand auger was turned with a T-handle. The soils encountered, in the exploratory hand auger borings, were continuously examined and visually classified in accordance with the Unified Soil Classification System (USCS). Figure 2 shows the approximate locations of the exploratory hand auger borings. Representative samples of the subsurface soils, encountered in the hand auger borings, were collected and sealed in plastic bags. These samples were transported to our Woodinville Office for storage (30 days). Geologic Settins 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 United States Geological Survey (USGS), Geologic Map of the Edmonds East Quadrangle, Washington, indicates that the property is underlain by Vashon Advance Outwash. The Vashon Advance Outwash is typically comprised of stratified sands and gravels, locally with silt and clay interbeds, deposited by the melt water of the advancing Vashon Glacier. Soil Profile and Subsurface Conditions The soils encountered in the exploratory hand auger borings were generally typical of those found in the described geologic unit. Exploratory Hand Auger Borings HA-1 and HA-2 encountered approximately 3 to 6 inches of topsoil and brush underlain by loose to medium dense, fine to coarse grained sand with variable amounts of silt and gravel (Advance Outwash) down to the termination depths of HA-1 and HA-2 (approximately 2.5 and 4.0 feet below the existing site grades, respectively). Exploratory Hand Auger Boring HA-3 encountered 3 inches of topsoil and grass underlain by 2 feet of loose to medium dense, fine to coarse grained sand with variable amounts of gravel and silt (Undocumented Fill). The fill is underlain by loose to medium dense, fine to coarse grained sand with variable amounts of gravel and silt (Advance Outwash) down to the termination depth of HA-3 (approximately 3 feet below the existing site grade). For additional information about the soils encountered, please refer to the attached logs of the exploratory hand auger borings. Groundwater The hand auger borings were checked for the presence of groundwater during and immediately following the excavation operations. At the date and time of our investigation groundwater was not encountered in any of the exploratory hand auger borings. Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 3 of 12 It should be recognized that water table elevations may fluctuate with time. The groundwater Ievel will be dependent upon seasonal precipitation, irrigation, land use, and climatic conditions, as well as other factors. Therefore, water levels at the time of the field investigation may be different from those encountered during the construction phase of the project. The evaluation of such factors is beyond the scope of this report. Groundwater flow may become heavier during construction, which takes place during the wet weather season. This may cause difficulties with the grading and excavation work. Certain remedial and/or de -watering measures may be required. Seismic Conditions The glacial soils encountered in the exploratory hand auger borings were generally medium dense. The overall soil profile generally corresponds to a stte class soil profile ,of D as defined by Table 1615.1.1 of the 2003 International Building Code (IBC). A site class soil profile of-D applies to a profile consisting primarily of medium dense to dense or stiff soils within the upper 100 feet. CONCLUSIONS AND RECOMMENDATIONS General Based on the findings of this investigation, it is our opinion that the proposed residential structure may be supported on a shallow foundation system bearing on the medium dense native soils, or on properly compacted structural fill, placed on the medium dense native soils. Local overexcavation and/or recompaction of loose soils may be necessary during footing excavation work. The depth and extent of the overexcavations will depend on the exact location of the proposed residential structure. Any footing overexcavations may be backfilied up to the original bottom of footing elevation with suitable material. The structural fill should be placed in maximum 8 inch thick (loose) horizontal lifts and the material should be compacted to at least 95 percent of the maximum dry density as determined by ASTM Test Method D 1557. In place density tests should be performed to verify proper moisture content and adequate compaction. Imported, granular (sand and gravel) fill may be required if moisture conditions do not permit proper placement and compaction of the existing on site soils. The same general procedure should be used in floor slab and pavement areas. Site Preuaration Site clearing should be limited to the areas necessary for construction of the single family residence and the associated driveway. Native vegetation should be left in place to the maximum extent possible along slope surfaces. Clearing should include removal of vegetation; trees and associated root systems; wood; existing utilities; structures including foundations, basement walls and floors; rubble; and rubbish. Site stripping should extend to a minimum depth of 4 to 8 inches (preliminary; based on our hand auger boring locations), or until all organics in excess of 3 percent by volume are removed. These materials will not be suitable for use as structural fill. However, stripped topsoil may be stockpiled and reused in landscape or non-structural areas. Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 4 of 12 After stripping operations and removal of any undocumented fill or unsuitable soils that may influence the building footprint, the building pad areas should be visually inspected to identify any loose areas. Any remaining loose soils should be overexcavated to the level of the medium dense native soils. The resulting excavations should be filled with approved on site material, or imported structural fill. Structural fill material should be within ± 2 percent of the optimum moisture content, and the soils should be compacted to a minimum of 95 percent of the maximum dry density based on ASTM Test Method D1557. During wet weather conditions, typically October through May, subgrade stability problems and grading difficulties may develop due to excess moisture, 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 contents. The on site native soils have variable silt contents and are considered moisture sensitive. If overexcavation is necessary, it should be confirmed through continuous monitoring and testing by a qualified geotechnical engineer or senior geologist. 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 (typically during the summer months). 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 the protection of exposed soils during the construction phase. It should be understood that even if Best Management Practices (BMP's) for wintertime soil protection are implemented and followed there is a significant chance that moisture disturbed soil mitigation work will still be required. Any buried structures encountered during construction should be properly removed and backfilled. Excavations, depressions, or soft and pliant areas extending below the planned finish subgrade levels should be cleaned to firm undisturbed soil, and backfilled with structural fill. In general, any septic tanks, underground storage tanks, debris pits, cesspools, or similar structures should be completely 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. A representative of our firm should be present during all site clearing and grading operations to test and observe earthwork construction Tfiis - te�stiirig and observation is anintegral part of our service, as acceptance of earthwoik construction is dependent upon compaction and stability of the material. The geotechnical engineer may reject any material that does not meet compaction and stability requirements. Further recommendations, contained in this report, are predicated upon the assumption that earthwork construction will conform to the recommendations set forth in this section and in the Structural Fill Section. Erosion Concern/Hazard 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 into the design of the erosion and sediment control features of the site: Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 5 of 12 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, provided precautions are taken using Best Management Practices (BMP's), limited grading activities can be undertaken during the wet season (generally October through April). It should be noted that this typically increases the overall cost of the project. 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. 5) Vegetation should be re-established in landscaped and slope areas prior to the onset of wet weather (typically October through April). The owner should understand that the landscaped and slope areas may require periodic maintenance. The owner should visually inspect the landscaped areas and slopes where vegetation has been re-established after adverse rain events and at least once a week during prolonged rain events until vegetation has taken root. Once the vegetation has taken root, the owner should visually inspect the landscaped slopes at least bi-annually for any variations or undesirable conditions. If any variations or undesirable conditions are observed a geotechnical engineer should be notified so that supplemental recommendations can be made. Temporary Excavations The on site soils have variable cohesion strengths, therefore the safe angles to which these materials may be cut for temporary excavations is limited, as the soils may be prone to caving and slope failures in temporary excavations deeper than 4 feet. Temporary excavations in the loose undocumented fill should be sloped no steeper than 1 1/aH: IV (horizontal to vertical) where room permits. Temporary excavations in the medium dense glacial soils should be sloped no steeper than 1H:1V (horizontal to vertical) where room permits. If the soil in the excavation is subject to vibration from heavy traffic, the temporary excavation should be sloped no steeper than 1'/2H:1 V (horizontal to vertical). All temporary cuts should be in accordance with Washington Administrative Code (WAC) Part N, Excavation, Trenching, and Shoring. The temporary slope cuts should be visually inspected daily by a qualified person during construction work activities and the results of the inspections should be included in daily reports. The contractor is responsible for maintaining the stability of the temporary cut slopes and minimizing slope erosion during construction. The temporary cut slopes should be covered with visqueen to help minimize erosion during wet weather and the slopes should be closely monitored until the permanent retaining systems are complete. Materials should not be stored and equipment operated within 10 feet of the top of any temporary cut slope. A Krazan & Associates geologist or geotechnical engineer should observe, at least periodically, the temporary cut slopes during the excavation work. The reasoning for this is that all soil conditions may not be fully delineated during the previous geotechnical exploratory work. In the case of temporary slope cuts, the existing soil Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 6 of 12 conditions may not be fully revealed until the excavation work exposes the soil. Typically, as excavation work progresses the maximum inclination of the temporary slope will need to be reevaluated by the geotechnical engineer so that supplemental recommendations can be made. Soil and groundwater conditions can be highly variable. Scheduling for soil work will need to be adjustable, to deal with unanticipated conditions, so that the project can proceed smoothly and required deadlines can be met. If any variations or undesirable conditions are encountered during construction Krazan & Associates should be notified so that supplemental recommendations can be made. Structural Fill Best Management Practices (BMP's) should be followed when considering the suitability of native material for use as structural fill. The silty native glacial soils have relatively high fines (silt and clay) contents and are considered moisture sensitive. The sandy native glacial soils have variable fines contents and may become moisture sensitive during times of heavy precipitation. The native glacial soils may also have elevated natural moisture contents, and may need to be dried back during dry, warm weather (typically during the summer months). The native glacial soils (sandy soils) are generally considered suitable for reuse as structural fill, provided the soil is relatively free of organic material and debris, and it is within ± 2 percent of the optimum moisture content. If the native glacial soils are stockpiled for later use as structural fill, the stockpiles should be covered to help protect the soil from wet weather conditions. We recommend that a representative of Krazan & Associates be on site during the excavation work to determine which soils are suitable for structural fill. It should not be taken for granted that the onsite soils may be used as the sole source for structural fill (especially during winter construction activities). During wet weather conditions the soils with higher silt and clay contents will be moisture sensitive, easily disturbed and most likely will not meet compaction requirements. Furthermore, during the winter the native soils typically have elevated natural moisture contents, which will limit the use of these materials as structural fill without proper mitigation measures. The contractor should use Best Management Practices to protect the soils during construction activities and be familiar with wet weather and wintertime soil work. An allowance for importing structural fill should be incorporated into the construction cost of the project (for wintertime construction this may be as high as 100 percent import). Imported structural fill material should consist of well -graded gravel or a sand and gravel mixture with a maximum grain size of 11/z inches and less than 5 percent fines (material passing the U.S. Standard 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 horizontal lifts not exceeding 8 inches loose thickness, moisture -conditioned as necessary, (moisture content of soil shall not vary by more than ±2 percent of optimum moisture) and the material should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D1557. In place density tests should be performed on all structural fill to verify proper moisture content and adequate compaction. Additional lifts should not be placed if the previous lift did not meet the compaction requirements or if soil conditions are not considered stable. Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 7 of 12 Groundwater Influence on Structures/Construction Groundwater was not encountered in any of the exploratory hand auger borings at the date and time of our field exploration. If groundwater is encountered during the construction work, the groundwater is most likely perched. This perched groundwater develops where vertical infiltration of surface precipitation is impeded by a relatively impermeable soil layer, resulting in horizontal migration of the groundwater within overlying more permeable soils. If groundwater is encountered during construction, we should observe the conditions to determine if de - watering will be needed. Design of temporary dewatering systems to remove groundwater should be the responsibility of the contractor. If earthwork is performed during or soon after periods of precipitation, the subgrade soils may become saturated. These soils may "pump," and the materials may not respond to densification techniques. Typical remedial measures include: discing and aerating the soil during dry weather; mixing the soil with drier materials; removing and replacing the soil with an approved fill material. A qualified geotechnical engineering firm should be consulted prior to implementing remedial measures to observe the unstable subgrade conditions and provide appropriate recommendations. Drainage and Landscaping The ground surface should slope away from building pads 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 surfaces. Roof drains should not be connected to the footing drains, but may use the same outfall piping if connected well away from the structure such that roof water will not backup into the footing drains. Subgrade soils in pavement areas should be sloped a minimum of 1 percent and drainage gradients should be maintained to carry all surface water to collection facilities, and/or dispersion trenches, away from slope surfaces. These grades should be maintained for the life of the project. The collection facilities and/or dispersion trenches should be tightlined away from slopes that exceed 30 percent and disposed of where down slope properties, structures and slopes are not jeopardized. Specific recommendations for and design of storm water disposal systems or septic disposal systems are beyond the scope of our services and should be prepared by other consultants that are familiar with design and discharge requirements. Infiltration systems should not be located on slopes that exceed 30 percent nor should systems be "stacked" or lined up with one another down the slope. Infiltration systems should not be located up slope of residences or retaining structures. Utility Trench Backfill Utility trenches should be excavated in accordance with Occupational Safety and Health Administration (OSHA) standards, by a contractor experienced in such work. The responsibility for the safety of open trenches should be borne by the contractor. Traffic and vibration adjacent to trench walls should be minimized; cyclic wetting and drying of excavation side slopes should be avoided. Depending upon the location and depth of some utility trenches, groundwater flow into open excavations could be experienced, especially during or shortly following periods of precipitation. Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 8 of 12 Generally, sandy soil conditions were encountered at shallow depths at this site. These soils have low cohesion strengths and can cave in trench wall excavations. Shoring or sloping back trench sidewalls may be required within these soils. All utility trench backfill should consist of imported structural fill or suitable on -site material. Utility trench backfill placed in or adjacent to buildings and exterior slabs should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D1557. The upper 5 feet of utility trench backfill placed in pavement areas should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D 1557. Below 5 feet, utility trench backfill in pavement areas should be compacted to at least 90 percent of the maximum dry density based on ASTM Test Method D1557. Pipe bedding should be in accordance with the pipe manufacturer's recommendations. The contractor is responsible for removing all water -sensitive soils from the trenches regardless of the backfill location and compaction requirements. The contractor should use appropriate equipment and methods to avoid damage to the utilities and/or structures during fill placement and compaction. Floor Slabs and Exterior Flatwork If slab on grade structures are proposed and reducing floor dampness is desired, such as in areas covered with moisture sensitive floor coverings, we recommend that concrete slab -on -grade floors be underlain by a 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 (less than 5 percent passing the U.S. Standard No. 200 Sieve), open -graded coarse rock of 3/a-inch maximum size. The vapor retarder sheeting should be protected from puncture damage. The exterior floors should be placed separately in order to act independently of the walls and foundation system. All fills required to bring the building pad to grade should be structural fill. Moisture within the structure may be derived from water vapors, which were transformed from the moisture within the soils. This moisture vapor can travel through the vapor membrane and penetrate the slab -on -grade. This moisture vapor penetration can affect floor coverings and produce mold and mildew in the structure. To minimize moisture vapor intrusion, it is recommended that a vapor retarder be installed in accordance with ASTM guidelines. It is recommended that the utility trenches within the structure be compacted, as specified in our report, to minimize the transmission of moisture through the utility trench backfill. Special attention to the immediate drainage and irrigation around the building is recommended. Positive drainage should be established away from the structure and should be maintained throughout the life of the structure. Ponding of water should not be allowed adjacent to the structure. Over -irrigation within landscaped areas adjacent to the structure should not be performed. In addition, ventilation of the structure (i.e. ventilation fans) is recommended to reduce the accumulation of interior moisture. Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 9 of 12 Foundations The proposed single family residence may be supported on a shallow foundation system bearing on the medium dense native soils, or on properly compacted structural fill, placed on the medium dense native soils. Continuous wall or column footings may be designed for a net allowable bearing pressured 2,000 pounds per squ..are foot (psf) dead plus live load, if the footings bear directly on the medium dense native's'o is or oil structural fill, placed on the medium dense native soils. Local overexcavation or recompaction of loose soils may be necessary. The depth and extent of this work will depend on the exact location of the proposed structure and can be determined during construction. 3 increase in the above value may be used for short duration, wind and seismic loads. Structural fill placed on bearing, native subgrade should be compacted to at least 95 percent of the maximum dry density based on ASTM Test Method D1557. Footing excavations should be inspected to verify that the foundations will bear on suitable material. Exterior footings should have a minimum depth of 18 inches below pad subgrade (soil grade) or adjacent exterior grade, whichever is lower. Interior footings should Have a mmimum depth of,12 inches below; pad subgrade (soil grade) or adjacent exterior grade, whichever is lower. Footings should have a minimum width of 12 inches regardless of load. If constructed as recommended, the total settlement is not expected to exceed 1 inch. Differential settlement, along a 20-foot exterior wall footing, or between adjoining column footings, should be less than 1/z inch, producing an angular distortion of 0.002. Most settlement is expected to occur during construction, as the loads are applied. However, additional post -construction settlement may occur if the foundation soils are flooded or saturated or if a strong seismic event results in liquefaction of the underlying soils. It should be noted that the risk of liquefaction is considered low, given the composition and density of the native, on site soils. Seasonal rainfall, water run-off, and the normal practice of watering trees and landscaping areas around the proposed structure, should not be permitted to flood and/or saturate footings. To prevent the buildup of water within the footing areas, continuous footing drains (with cleanouts) should be provided at the bases of the footings. The footing drains should consist of a minimum 4-inch diameter perforated pipe, sloped to drain, with perforations placed down and enveloped by 1-inch sized washed rock in all directions and filter fabric to prevent the migration of fines. Resistance to lateral footing displacement can be computed using an allowable friction factor of 0.30 acting between the bases of foundations and the supporting subgrade. Lateral resistance for footings can alternatively be developed using an allowable equivalent fluid passive pressure of 250 pounds per cubic foot (pcf) acting against the appropriate vertical footing faces. The allowable friction factor and allowable equivalent fluid passive pressure values include a factor of safety of 1.5. The frictional and passive resistance of the soil may be combined without reduction in determining the total lateral resistance. A 1/3 increase in the above values may be used for short duration, wind and seismic loads. Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 10 of 12 Lateral Earth Pressures for BasementlRetaining Walls We have developed criteria for the design of retaining or below grade walls, in case this information is required. Our design parameters are based on retention of the in place soils. The parameters are also based on a level backfill condition behind and in front of the wall. Walls may be designed as "restrained" retaining walls based on "at -rest" earth pressures, plus any surcharge on top of the walls as described below, if the walls are attached to the buildings and/or movement is not acceptable. Unrestrained walls may be designed based on "active" earth pressure, if the walls are not part of the buildings and some movement of the retaining walls is acceptable. Acceptable lateral movement equal to at least 0.2 percent of the wall height would warrant the use of "active" earth pressure values for design. The following table, titled Wall Design Criteria, presents the recommended soil related design parameters for retaining walls with level backfill. Contact Krazan & Associates, Inc. if an alternate retaining wall system is used. Wall Design Criteria "At -rest" Conditions 55 psf /foot of depth "Active" Conditions 35 psf/foot of depth Passive Earth Pressure on Low Side of Wall (Allowable; F.S. = 1.5 included) Neglect upper 2 feet; then 250 psf/linear foot of depth. Soil -Footing Coefficient of Sliding Friction (Allowable; F.S. = 1.5 included) 0.30 The stated .lateral earth pressures do not include the effects of hydrostatic pressure (from water accumulation), seismic loads or loads imposed by construction equipment, roadways or foundations (surcharge loads). To minimize the lateral earth pressure and prevent the buildup of water pressure against the walls, continuous footing drains (with cleanouts) should be provided at the bases of the walls. The footing drains should consist of a minimum 4-inch diameter perforated pipe, sloped to drain, with perforations placed down and enveloped by 6 inches of pea gravel in all directions and filter fabric to prevent the migration of fines. The backfill adjacent to and extending a lateral distance, behind the walls, of at least 2 feet should consist of free -draining granular material. All free draining backfill should contain less than 3 percent fines (passing the U.S. Standard No. 200 Sieve) based upon the fraction passing the U.S. Standard No. 4 Sieve with at least 30 percent of the material being retained on the U.S. Standard No. 4 Sieve. It should be realized that the primary purpose of the free - draining material is the reduction of hydrostatic pressure. Some potential for the moisture to contact the back face of the wall may exist, even with treatment, which may require that more extensive waterproofing be specified for walls, which require interior moisture sensitive finishes. We recommend that the backfill be compacted to at least 90 percent of the maximum dry density based on ASTM Test Method D1557. In place density tests should be performed to verify adequate compaction. Soil compactors Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 11 of 12 place transient surcharges on the backFill. Consequently, only light hand operated equipment is recommended within 3 feet of walls so that excessive stress is not imposed on the walls. 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. Furthermore, Krazan & Associates is not responsible for the contractor's procedures, methods, scheduling or management of the work site. 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 that the recommendations can be reviewed and reevaluated. This report is a limited 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 hand auger boring log, regarding odors, unusual or suspicious items, or conditions observed are strictly for descriptive purposes and are not intended to convey engineering judgment regarding potential hazardous and/or toxic assessments. Krazan & Associates, Inc. Ten Offices Serving The Western United States KA No. 092-06078 May 12, 2006 Page No. 12 of 12 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. We hope that this report provides the information required at this time. If you have any questions, or if we may be of further assistance, please do not hesitate to contact our office at (425) 485-5519. Respectfully submitted, KRAZAA & SSOCIATES, INC. Phil Haberman, L.G. Senior Engineering Geologist PH/sic Attachments: Figures (5) Sean L. Caraway, P.E. Geotechnical Division Manager Krazan & Associates, Inc. Ten Offices Serving The Western United States H -3 Timber WoAls H -1 Alder Street LEGEND Hand Auger HA-1 Location Site Phan Proposed Single Fomily Residence Figure 2 No scab Job NuMbere 092-06078 Balm ate, se, - Ixrzarl ; n &ASSOCIATES, INC. ]�Q�� T�QI Stta P10Y1 Project: Jones SFR, Log 0f Hand Boring HA-1 Project No: mamoa ` Client: John Jones Surface Elevation: Figure No 2 Location: m «s &A Datum: Logged By: B Depth to Wks N/A . Initial: A Completion: SUBSURFACE PROFILE SAMPLE Dynamic Cone Water Content / . E E - Penetrometer Wiz) Description2 © £ ek (Bae1z.75 g 201-0-1 6 �e?� R Cn (A F_ CO\ co 2 k« S 0 Ground Surface ' } GRAS zLAN SC PING. --------------------------------- .££��NDWF G�£mm ! ;; Medium dense bden$ fine to coarse grained, dark brow, moist \ . . -Abundant organics (rootlets) naol -Increased sand below 1.25' . S Gab End yBorehole | � . a . � a ; .=— Drill Method: Hand Auger Kazan an Associates D.riDate: SBZZeo 19 0114 m Ave. NE #F-300 Driller: BBC Woodinville, Washington SampleMethod: Gmb .98072 Sheet: 1 of I Project: Jones SFR Log of Hand Boring HA-2 Project No: 092-06078 Client: John Jones Surface Elevation: Figure No: 3 Location: Edmonds, WA Datum: Logged By: BBC Depth to Water NIA Initial: At Completion: SUBSURFACE PROFILE SAMPLE Dynamic Cone Penetrometer (Blows/1.75") 20 40 60 80 Water Content N Wp 1---0 --1 WI 20 40 60 80 a a o m Description E z m E U Q r—'' o. & cn - n 5 _ c6 3 z m 0 r% Ground Surface GRAS_S/L_ANDSCAPING ________ _ _______ F Y SILTY SAND WITH GRAVEL (SM) t 1 Loose to medium dense, fine to coarse grained, dark I I , brown, moist 1 -Abundant organics (rootlets) in soil S1 Grab ' -Soil is slightly cohesive below 1' 1 i i 1 _ � 1 1 ` i s 1 I � t � i S2 Grab i i i i i ! f f r � 1 1f 1 1 ! t I S3 Grab 1 1 = 1 ' SILTY SAND WITH GRAVEL (SM) S4 Grab Loose to medium dense, fine to coarse grained, gray/dark E brown, very moist, with trace clay -'Organics rootlets resent in material i ? End of Borehole 1 5 i 1 -------- --- -- - I , Drill Method: Hand Auger Krazan and Associates Drill Date: 5/8/06 19501 144th Ave. NE #F-300 Driller: BBC Woodinville, Washington Sample Method: Grab 98072 Sheet:1 of 1 Project: Jones SFR Log of ¢farad Boring HA-3 Project No: 092-06078 Client: John Jones Surface Elevation: Figure No: 4 Location: Edmonds, WA Datum: Logged By: BBC Depth to Water NIA Initial: At Completion: SUBSURFACE PROFILE SAMPLE Dynamic Cone Water zH ^ Penetrometer Content (o ) Description t- (Blows/1.75") a E E c. E 3 3 wp 1-0--J WI o z �° 20 40 60 80 20 40 60 80 0 Ground Surface _ GRASSILANDSCAPING GRAVELLY SAND WITH TRACE SILT (SP) (FILL) Loose to medium dense, fine to coarse grained, ' olive brown, moist I E K -Abundant organics (rootlets) in soil i [ -Dark brown color below 1' i S1 Grab .• \ 3 i i i 1 i •�� ... 1 I 1 i 1 � GRA VEL L Y SIL TY SAND (SM) S2 Grab j Loose to medium dense, fine to coarse grained, dark i brown, moist I a -Organics (rootlets) present in material i i I i ! i i i 1 1 -.may.---�--Y-�-tom--- 1 ! 1 I t t f` � 1 f 1 s i i s -- - - -- End of Borehole 5 1 1 1 � j 1 � I j 1 I 3 � i i i I 1 i i j 1 -------`---------- Drill Method: Hand Auger Krazan and Associates Drill Date: 5/8/06 19501 144th Ave. NE #F-300 Driller: BBC Woodinville, Washington Sample Method: Grab 98072 Sheet:1 of 1