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rossgeo.pdfZZA Zipper Zeman Associates, Inc. Geotechnical and Environmental Consulting A Irerracan Company RECEIVE® OCT Z Q 2006 E.DM 06-59 Project No. 81065103 14 August 2006 uenzer DEVELOPMENT SERVICES CTR. Mr. Michael Q CITY of EDMONDS Mr. Stephen Roth 9102 Olympic View Drive Edmonds, Washington 98026 Subject: Limited Geotechnical EngineeringEvalua CTYC Proposed Residential Improvements 9102 Olympic View Drive Edmonds, Washington i Gentlemen: H l 5X2006 EECE In accordance with your request and authorization, Zipper Zeman Associa es, . � has conducted a limited geotechnical engineering evaluation for the above -referenced project. Our services were provided in general accordance with our Proposal for Limited Geotechnical Engineering Service letter (P-3386, 6 July 2006), authorized on 18 July 2006. The purpose of this evaluation was to assess site conditions in order to provide conclusions regarding the nature of regulated geologic hazards at the subject site relative to proposed improvements to the dwelling at the property, as well as to provide geotechnical engineering recommendations pertinent to the proposed improvements. This report is an instrument of service and has been prepared in accordance with generally accepted geotechnical engineering design practice for the exclusive use of the Mr. Michael Quenzer and Mr. Stephen Roth, and their agents, for specific application to the stated purpose and site location. SITE AND PROJECT DESCRIPTION The project site is a developed single-family residential property. The site includes a relatively level bench to the southeast, upon which the dwelling and driveway are located. A landscaped slope extends downward to the west and northwest. A concrete slab extends along the west side of the dwelling, and the southwest corner of the slab has essentially no setback from the adjacent western. slope. A wood deck is constructed above the slab. We understand that you plan to remove the deck, and then reconstruct it such that it is 6 to 8 feet narrower than the current configuration. The outer 6 to 8 feet of the slab below the deck will be removed as well. This configuration would effectively decrease the footprint of the impervious surface adjacent to the slope and increase the building setback from the slope. An extension to the deck would be added to the north, above the existing driveway. A short section of new exterior wall will be added along the east side of the dwelling. We understand that measures intended to collect and convey surface water will be incorporated into the new deck. You have indicated that there will be no significant grading associated with the construction. 18905 331 Avenue West #117, Lynnwood, WA 98036 425-771-3304 Fax: 425-771-3549 Our authorized scope of services included: Querzer / Roth Residence Project No_ 81065103 14 August 2006 Page 2 • Completing a visual reconnaissance of the site to identify surficial landforms that may be indicative of past or ongoing slope instability, erosion and drainage; • Excavating two exploratory borings; • A review of pertinent geologic publications and maps as well as aerial photographs and other remote sensing imagery, • Evaluations regarding the on-site presence or absence of geologically hazardous areas regulated under the Edmonds Community Development Code (ECDC); + Evaluating general geotechnical engineering considerations regarding design. and construction of foundations for the new deck and new exterior wall, and; • Preparation of this written report. Our authorized scope of services did .not include a quantitative or qualitative evaluation as to the potential presence of regulated environmental contaminants at the prosect site. In accordance with your request, we also met with Mr. Steven Bullock, Senior Planner with the City of Edmonds. The purpose of the meeting was to clarify the City's expectations for the geotechnical report given the nature of the property and the proposed site improvements. DOCUMENT REVIEW We reviewed the following documents over the course of our evaluation: • Chapter 23 of the ECDC; • The Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles, Washington (U.S.G.S. Map MF -1541, 1983); • Published seismic data from the U.S.G.S. Earthquake Hazards Program web site; • Undated aerial photograph accessed from the TerraServer web site. SITE CONDITIONS The site conditions were evaluated in August 2006. The surface and subsurface conditions are described below, while the exploration procedures and interpretive logs of the 81065103,14 August 2006 Quenzer / Roth Residence Project No. 81065/03 14 August 2006 Page 3 explorations are presented in Appendix A. The approximate exploration locations are shown on Figure 1, the Site and Exploration Plan. Surface Conditions The property is located on a west facing slope that extends below and above to the west and east, respectively. Ground surface elevations range from a high of 256 feet near the southeastern portion of the dwelling to a low of 206 feet near the property's southwest comer. A single-family residential structure and a concrete driveway are located in the higher eastern portion of the site. The slope extending below the dwelling and driveway to the west is landscaped and supports gravel -surface walking trails. A small section of lawn extends south of the dwelling. The narrow strip between the dwelling and the east property boundary consists of ornamental plantings and a walkway. A small segment of the slope to the west of the dwelling is inclined as steeply as approximately 75 percent and has greater than 10 feet of relief. The area supporting the dwelling and the southern portion of the driveway is largely level, while the north end of the driveway slopes down gradually to the street. We did not observe evidence of surface water erosion or past or ongoing landslide activity at the site. We did not observe significant cracking of the exposed portions of the dwelling's perimeter foundation. The configuration of the upper portion of the slope west of the dwelling suggests that fill material may have been placed there. The dwelling is a daylight basement configuration, and it isnot uncommon for fill material to be present on the lower side of such dwellings. The southwest corner of the concrete slab located along the west side of the dwelling appears to have settled and this portion of the slab slopes gently to the west. Published Geologic Literature According to the publication Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles, Washington, the project site is underlain by Vashon lodgement glacial till. Downslope and west of the site, occurrences of advance outwash deposits (primarily sandy soil with some fine grained soil interbeds) have been mapped. Conditions disclosed by the exploratory borings generally confirmed the geologic conditions described in the referenced publications. Based on the results of our subsurface exploration, it appears that glacial till and advance outwash deposits underlie the property. The native soils were mantled by fill material. at the boring locations. Subsurface Conditions The subsurface evaluation consisted of completing two hand auger explorations (HA -1 and HA -2) at the approximate locations shown on Figure 1, the Site and Exploration Plan. Appendix A includes descriptive logs of the explorations and the procedures utilized in the subsurface exploration program. Variations in subsurface conditions may exist between the 81065103,14 August2006 Quenaer 1 Roth Residence Project No. 81065103 14 August 2406 Page 4 exploration locations and the nature and extent of variations between the explorations may not be evident until construction. If variations then appear, it may be necessary to reevaluate the recommendations of this report_ A general description of the subsurface conditions encountered during our exploration program is presented below. Refer to the logs in Appendix A for a detailed description of the subsurface conditions. Borings HA -1 and HA -2 were advanced along the south and west sides of the concrete slab located along the west side of the dwelling. Each of the explorations disclosed surficial fill material that generally consisted of very loose to loose silty sand with secondary amounts of gravel, some organic material, and in the case of boring HA -1, some pieces of ceramic tile and wire. The fill material extended to depths of approximately 5 feet and 6 feet at the locations of boring HA -1 and HA -2, respectively. The fill was underlain by medium dense, silty, gravelly sand at the location of boring HA -1. We have interpreted this material to be representative of weathered glacial till. A relic topsoil horizon of loose, silty sand with some fine organic material and roots was present below the fill at the location of boring HA -2. The relic topsoil was underlain by very stiff, fine sandy silt. This .material may be representative of either weathered till or the advance outwash deposits, in our opinion. Soil exposures in the cut bank along the east property boundary exposed dense, brown, gravelly, silty sand. These soils are consistent with glacial till, in our opinion. . Groundwater Conditions Neither a distinct groundwater table nor perched groundwater were observed at the exploration locations. However, groundwater levels should be expected to fluctuate throughout the year due to seasonal precipitation variation, irrigation, site utilization, and other factors. The soils observed at the boring HA -1 location were generally in a damp to moist condition. The soils observed at the boring HA. -2 location were wet. The planter area along the west side of the concrete slab where boring HA -2 was located is irrigated regularly. We attribute the high moisture content of the soils at this location to irrigation, rather than groundwater. CONCLUSIONS AND RECOMMENDATIONS We understand that the proposed site improvements include removing a portion of the concrete slab along the west side of the dwelling, replacing the existing deck above the slab with a smaller one, constructing an extension of the deck to the north, and constructing a segment of new exterior wail along the dwelling's east side. New foundations will be needed for the new deck and the new wall. The project is considered feasible from the geotechnical perspective, in our professional opinion. Presented below are our conclusions and recommendations regarding regulated geologically hazardous areas and general site development considerations. 81065103, 14 August 2006 Regulated Geologically Hazardous Areas Quenzer / Moth Residence Project No. 81065103 14 August 2006 Page 5 As part of the plan review process, the City of Edmonds will evaluate the significance of regulated geologically hazardous areas as defined in the ECDC. Our conclusions and recommendations regarding these areas are presented below. Erosion Hazard The ECDC identifies an erosion hazard area as one containing soils having a severe to very severe erosion hazard in the presence of flowing surface .water according to the USDA Soil Conservation Service. Such soils include the Alderwood gravelly sandy loam (AgD) when they are present on slopes steeper than 15 percent. The site -characteristic glacial till and advance outwash deposits are consistent with these soils. Eased upon our document review and site observations, it is our opinion that the portions of the site with 15 percent or greater slope inclinations meet the ECDC criteria for an erosion hazard area. However, it should be noted that the site currently does not exhibit evidence of surface water flow or erosion, even though surface water from the existing deck drips onto the top of the slope. Mitigation of potential .erosion hazards can be achieved by incorporating best management practices into the construction methods and design of the improvements. Landslide Hazard The ECDC utilizes a landslide hazard area definition that includes slopes with the potential for landslide activity. Such areas include slopes steeper than 40 percent with 10 or more feet of relief. Much of the slope west of the dwelling meets these criteria. It should be noted that the slope lacks groundwater seepage, lobate terraces, tension cracks, or other surface features that maybe indicative of past or current unstable slope conditions. During our site reconnaissance we observed several large trunks of trees that were removed over the past year when the western slope was landscaped (in compliance with ECDC requirements, we might add). The trunks exhibit some degree of curvature. Givers the lack of other surface features that could in some circumstances be indicative of unstable slope conditions, it is our opinion that the trunk curvature is more likely than not related to growth adjustments resultant from solifluction (slow downslope creep of near -surface weathered soils) rather than slope instability. Solifluction is a common mass wasting process that does not reflect inherent instability of the underlying unweathered native soils. Seismic Hazard The site is underlain by glacially consolidated soil and does not support a shallow groundwater table. The site would not be subject to liquefaction during a seismic event given the soil density and lack of groundwater, in our opinion. It is our opinion that the site does not meet the criteria for a seismic hazard area as described in the ECDC. 81065103,14 August 2006 Buffer and Building Setback Considerations Quenzer / Roth Residence Project No. 81065103 14 August 2006 Page 6 The ECDC requires establishing buffers and building setbacks from geologically hazardous areas. The lateral separation of the concrete slab on the west side of the dwelling from the western slope ranges from a maximum of approximately 6 feet at the northwest corner to no separation at the southwest corner. The current plans call for removing the western 6 to 8 feet of the slab, and the new deck above the slab will not extend as far to the west as the existing deck. This condition will effectively increase the lateral separation between the western slope and the impervious surfaces represented by the deck and slab. Provided that the deck is constructed with a surface water drainage system that will reduce the likelihood of uncontrolled surface water flow onto the western slope, it is our opinion that the proposed site improvements will not have an adverse effect on the adjacent slope. The proposed construction actually presents an opportunity to improve surface water drainage relative to the western slope. Seismic Criteria Geotechnical earthquake engineering input to development of the general design response spectrum of the International Building Code 2003 requires a site class definition and short period (Ss) and 1 -second period (Sl) spectral acceleration values. The USGS National Seismic Hazard Mapping Project tt ://e hazma s.us s. ovn computes the 2002 spectral ordinates (5 percent damping) at building periods of 0.2 and lA seconds for ground motions at the project site with a 2 percent probability of exceedance in 50 years as 1.26898 and 0.43738, respectively. Therefore, we recommend that Ss and S1 be assigned values of 1.2689g and 0.4373g, respectively. Based on the subsurface conditions encountered at the site and published geologic literature, we estimate that the average properties of the upper 100 feet of the site profile correspond to Site Class C, consistent with very dense soil having a Standard Penetration Resistance of greater than 50, a shear wave velocity between 1,200 and 2,500 feet per second, and an undrained shear strength greater than or equal to 2,000 pounds per square foot. Conventional Deck Foundation Recommendations The new deck will be supported by isolated .columns extending below the outer western edge of the deck. Based upon conditions observed at the exploration locations, it appears that much of the concrete slab below the deck is supported by loose fill material. In order to reduce the likelihood of deck foundation settlement, we recommend supporting the deck by foundations that bear upon at least medium dense or stiff native stiff native soils below the fill material that supports the slab. We do not recommend supporting the new deck on the existing concrete slab. The native soils adequate for foundation support were observed at depths of approximately 5 feet and 6.5 feet at the exploration locations. It should be noted that the lateral and vertical extent of the fill, and its physical characteristics, are likely to vary across the site. 81065103, 14 August 2006 Conventional Foundations Quenzer / Roth Residence Project No. 81065103 14 August 2006 Page 7 It will be necessary to cut the concrete slab in order to construct the deck foundations. It will then be necessary to excavate through the existing fill and any underlying loose, soft, or organic native soil such that foundations bear upon at least medium dense or stiff native soils. Forming and casting the footings in excavations that extend through the fill material may be difficult. It would be feasible from the geotechnical perspective to construct the footings at the recommended minimum foundation embedment depth within compacted structural -fill material, or Controlled Density Fill (CDF) with a minimum 50 psi compressive strength, which has been used to backfill the excavations that extend to the recommended bearing stratum. In the event that the foundation excavations are backfilled with structural fill material, the fill should be placed and compacted in accordance with the recommendations for structural fill presented subsequently in this report. The compacted structural fill prism should extend outward from and below the foundation edges at an inclination no steeper than 1H:1 V. In the event that the excavations are backfilled with CDF, the excavation width is recommended to extend at least one foot laterally from the foundation edges. The excavation required for the CDF backfilling alternative will be less extensive than that required if compacted structural fill is placed below the foundations. Allowable Bearing Pressure Foundations constructed above the recommended bearing stratum, or above compacted structural fill or GDF placed above the recommended bearing stratum, may be designed for a maximum allowable bearing pressure of 1,500 pounds per square foot (psf). A one-third increase of this value may be utilized for short term wind or seismic loading. We anticipate that total settlement of foundations constructed in accordance with the recommendations presented herein may experience total settlement on the order of approximately 1 inch, with differential settlement approaching half of the total settlement. Foundation excavations should be free of soft or loose soil, slough, debris, or standing water prior to pouring concrete in order to reduce the settlement potential. Foundation concrete should not be poured if the subgrade soils are frozen. Footing Depth and Width Foundations should extend at least 18 inches below the lowest adjacent grade for frost protection. Foundation dimensions should conform to applicable sections of the Edmonds building code. Passive Resistance An allowable base friction value of 0.30 and a maximum allowable passive resistance of 140 pef may be utilized for those foundations embedded at least 18 inches below grade. The 81065103,14 August 2006 upper 1 foot of embedment should be neglected when evaluating passive resistance. A structural engineer should prepare the foundation design. Pin Pile Foundation Recommendations General Pin piles comprise relatively small diameter steel pipe which are driven into the ground with a pneumatic or hydraulic jackhammer or percussion driver to designated "refusal" criteria. Pile lengths of 5 to 10 feet are commonly used. Successive pile lengths are either compression coupled or welded. Once the piles are installed, they are cut off to a pre -determined elevation, and lengths of reinforcing steel or top plates are generally welded to the top. The tops of the piles are then incorporated into a new floor slab or foundation, as appropriate. Vibration is associated with the needle pile installation. The purpose of installing driven pin piles is to transmit foundation loads through the unsuitable existing fill material to adequate bearing soils below the fill. This methodology eliminates the need for removing the existing loose fill material. The use of driven pin piles for support of the new deck is feasible from the geotechnical perspective, in our opinion. Pile Installation Should pin piles be selected as the foundation support alternative, we recommend that 2 - inch inside diameter, Schedule 80 steel pipe be utilized for the project. The piles should be installed with a minimum 90 -pound hydraulic or pneumatic jackhammer equipped with stirrups such that the operator can apply body weight as the piles are installed. Each of the piles should be driven to "refusal". Refusal is defined as 1 -inch or less of penetration into the ground over a 1 -minute interval of sustained driving. Determination of the depth to suitable bearing soils and the resultant pile capacities and depths will require field engineering decisions. We recommend that a ZZA representative observe the pile installation and refusal criteria achievement. Pile Capacity An allowable 5,000 pound axial compressive load for each 2 -inch inside diameter, Schedule 80 steel pile driven to refusal as described herein may be utilized for design. For preliminary planning purposes, we suggest that a minimum 10 -foot driven pile length below existing grades be considered. However, variation in pile lengths should be expected and we recommend that the construction budget include a contingency for longer pile lengths. Obstructions within the fill may prevent pile penetration to the necessary depths, and may require relocating some. piles or removal of debris. A lateral capacity should not be assigned to the plumb 2 -inch piles. Lateral loads should be accommodated by batter piles, grade beams. A' structural engineer should prepare the pile foundation. 8 1065103, 14 August 2006 A Exterior Wall Foundation Recommendations Quenzer / Roth Residence Project No, 81065103 14 August 2006 Page 9 A section of new exterior wall is proposed for construction near the northeast corner of the dwelling adjacent to the entry stairs. Based upon observations of soil exposures immediately to the east, we anticipate that glacial till soils will be present at foundation grade; this should be verified during construction. In the event that excavation for the new wall foundation discloses other soil conditions, we should be consulted. Allowable Bearing Pressure It will be feasible from the geotechnical perspective to construct the new wall foundation to bear upon at least medium dense or stiff, undisturbed native soil. Foundations constructed above the recommended bearing stratum may be designed for a maximum allowable bearing pressure of 2,000 pounds per square foot (psf). A one-third increase of this value may be utilized for short term wind or seismic loading. We anticipate that total settlement of foundations constructed in accordance with the recommendations presented herein may experience total settlement on the order of approximately I inch, with differential settlement approaching half of the total settlement. Foundation excavations should be free of soft or loose soil, slough, debris, or standing water prior to pouring concrete in order to reduce the settlement potential. Foundation concrete should not be poured if the subgrade soils are frozen. Footing Depth and Width Foundations should extend at least 18 inches below the lowest adjacent grade for frost protection. Foundation dimensions should conform to applicable sections of the Edmonds building code. Passive Resistance An allowable base friction value of 0.35 and a maximum allowable passive resistance of 250 pcf may be utilized for those foundations embedded at least 18 inclies below grade. The upper 1 foot of embedment should be neglected when evaluating passive resistance. A structural engineer should prepare the foundation design. Backfilled Walls All backfill placed behind conventional cast -in-place concrete walls, including around foundation stem walls, should be placed in accordance with our recommendations for structural. fill. The following recommended earth pressures, presented as equivalent fluid weights, are based on the assumption of a uniform level granular backfill with no buildup .of hydrostatic pressure behind the wall. To minimize lateral earth pressures and prevent the buildup of hydrostatic pressures, the wall backfill within 24 inches of the wall should consist of a free- 81065103, ree-S1065103, 14 August 2006 Quenzer / Roth Residence Project No. 81065103 14 August 2006 Page 10 draining granular material coupled with a perforated pipe drain placed at the base of the wall backfill. The drain should consist of a minimum 4 -inch diameter rigid perforated pipe, placed with the perforations facing down, and embedded in at least a 6 -inch thick envelope of clean, free -draining granular material, such as pea gravel. Footing drains should be directed toward appropriate storm water drainage facilities. Roof drains should not be connected to the footing drains in such a fashion that water from the roof could enter the foundation drains. If the backfilled walls are structurally restrained from lateral movement at the top, we recommend that they be designed for an "at -rest" equivalent fluid weight of 50 pounds per cubic foot (pef). If the tops of the walls are free to move laterally in an amount equal to at least 0.1 percent of the wall height during placement of backfill soils, they may be designed for an "active" equivalent fluid weight of 35 pcf. Surcharges due to sloping ground, adjacent footings, vehicles, construction equipment, etc., must be added to these values. The above equivalent fluid pressures assume that the backfill was compacted to approximately 90 percent of the modified Proctor maximum dry density. Additional compaction adjacent to the wall will increase the earth pressure, while a lesser degree of compaction could permit post construction settlements. Structural fill It is our understanding that there are currently no plans to fill along the western portion of the site where the existing slab will be partially removed and the existing deck rebuilt. We anticipate that there will be some fill material placed behind the new exterior wall near the current northeast entry. All fill material should be placed in accordance with the recommendations herein for structural fill. Prior to placement, the surfaces to receive structural fill should be firm and non -yielding and free of standing water or deleterious material such as organics or debris. All structural fill should be free of organic material, debris, or other deleterious material. Individual particle size should generally be less than b inches in diameter. Structural fill should be placed in lifts no greater than 9 inches in loose thickness and each lift should be compacted to at least 90 percent of the modified Proctor maximum dry density as determined by the ASTM D 1557 test procedure. The suitability of soils for structural fi11 use depends primarily on the gradation and moisture content of the soil when it is placed. As the amount of fines (that soil fraction passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult, or impossible, to achieve. Generally, soils containing more than about 5 percent fines by weight (based on that soil fraction passing the U.S. No. 4 sieve) cannot be compacted to a firm, non -yielding condition when the moisture content is more than a few percent from optimum. The optimum moisture content is that which yields the greatest soil density under a given compactive effort. We recommend that a "clean", free -draining pit -run sand and gravel be used to backfill the new wall. Such material should contain less than 5 percent fines, based on that soil fraction 81065103,14 August 2006 passing the U.S. No. 4 sieve, and not contain discrete particles greater than 6 inches in diameter. It should be noted that the placement of structural fill is, in many cases, weather -dependent. Delays due to inclement weather are common, even when using select granular fill. Surface Water Drainage Roof runoff from the dwelling and deck should be directed to a permanent surface water collection system that conveys water to the storm sewer. Surface water should not be directed to splash blocks or other drainage features on or adjacent to the western slope. The intent of this recommendation is to reduce the potential for surface water from the dwelling and deck to flow in an uncontrolled manner onto the adjacent slope which is highly susceptible to disturbance by flowing water. We observed that the downspout at the southwest corner of the dwelling directs water to a 4 -inch diameter concrete pipe that extends below grade. The pipe is clogged and likely does not except much water from the downspout, if any. We recommend that the condition of the site's surface water drainage system be inspected for functionality during the proposed construction. Should deficiencies be identified, they should be rectified so that water from the site's impervious surfaces drains to the storm system in the street. Erosion Mitigation Recent landscaping efforts on the western slope included placing jute matting and mulch on the ground surface. These materials are expected to help mitigate future erosion.. We recommend controlling surface water from the site's impervious surfaces during construction of .the proposed improvements such that water does not flow over the western slope. This may require the use of temporary piping to convey water to the slope toe or the placement of temporary berms along the slope edge to prevent uncontrolled surface water flow. Steep Slope Considerations There are some latent risks associated with steeply sloping property that require vigilance on the part of the owner or occupant in order to reduce the potential for erosion or slope movement. • Landscape irrigation systems should be operated only to the degree necessary to maintain vegetation health. Extensive and unnecessary irrigation on or near slopes can lead to erosion, as well as saturation of soils which may promote slope movement. Irrigation system plumbing should be inspected on a regular basis and repairs should be made promptly when deficiencies are identified. We also recommend that the irrigation system only be used when the owner or occupants are present. This will reduce the likelihood of improper irrigation taking place. • Regular inspections of the water supply and sewer plumbing will increase the likelihood of discovering leaks, should they occur. Plumbing leaks should be repaired promptly. 81065103, 14 August 2006 ZZAQuenzer / Roth Residence Project No. 81065103 44 August 2006 Page 12 JIM— • Fill material should not be placed on the western slope unless it is done in an engineering controlled manner. Closure The conclusions and recommendations presented in this report are based, in part, on the explorations accomplished for this study. The number, location, and depths of the explorations were completed within the constraints of budget and site access so as to yield the information to formulate the recommendations. We appreciate the opportunity to have been of service on this project and would be pleased to discuss the contents of this report or other aspects of this project with you at your convenience. Please call if you have any questions or need additional information. Respectfully Submitted, ZIPPER ZEMAN ASSOCIATES., INC. 1 David C. Williams, L.E.G. Associate NAlf John E. Zipper, P.E. 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Cly3H83AO DNI_SIX3 I ' ,I Ijl vRUn! C 31.]a L 3NLL5!XS!X f � 1 APPENDIX A. FIELD EXPLORATION PROCEDURES AND LOGS APPENDIX A FIELD EXPLORATION PROCEDURES AND LOGS Project No.: 81065103 Our field exploration for the project included advancing two hand auger explorations (HA -1, HA -2) and completing a visual site reconnaissance, Approximate exploration locations are shown on the Site and Exploration Plan, Figure 1. The Iocations of the. explorations were determined by measuring distances from existing site features with fiberglass and steel tapes relative to a site plan provided by ai Architects. As such, the exploration locations should be considered accurate to the degree implied by the measurement method. The approximate site-specific ground surface elevation at each exploration and infiltration test location was determined by interpolating the grade information shown on the referenced site plan. The following sections describe our procedures associated with the exploration. Descriptive logs of the explorations are enclosed in this appendix. Soil Boring Procedures The borings were advanced by hand through the use of a post hole digger, breaker bar, and a 3.25 -inch diameter hand auger. Throughout the drilling operation, soil samples were obtained as cuttings, continuously brought to the ground surface as each exploration was advanced. Our representative visually classified the soils, kept a detailed log of each exploration, and placed representative samples in moisture tight containers for transport to our laboratory. Granular soil density and cohesive soil consistency were evaluated through the use of the Dynamic Cone Penetrometer (DCP) in general accordance with procedures described in ASTM Special Technical Publication No. 399. DCP blowcounts, NC, are shown on the logs in this appendix. The enclosed exploration logs indicate the vertical sequence of soils and materials encountered in each hand auger boring, based primarily on our field classifications and supported by our subsequent laboratory testing. Where a soil contact was observed to be gradational or undulating, our logs indicate the average contact depth. We estimated the relative density and consistency of in situ soils by means of the excavation characteristics and by the sidewall stability. Our logs also indicate the approximate depths of any sidewaU caving or groundwater seepage observed, as well as all sample numbers and sampling locations, Zipper Zeman Associates Inc. 18905 — 33A Avenue West, Suite 117 Lynnwood, Washington 98036 (425)771 -3304 Hand Auger Boring >ElA-1 Location•. See Figure 1 A rox.round surface elevation feet): 247 Project: Quenzer 1 Roth Residence Project No.: J-81065103 Date Excavated: 2 August 2006 Depth (feet) Material Description Nc Moisture Sample Testing 2;� inches grass sod and fine roots above very loose to loose, damp, brown, silty SAND with some gravel and scattered pierces of tile and wire (Fill) ------------------------------------------------ Loose, damp to moist, gray -brown, fine to medium SAND with trace coarse sand and fine gravel (Fill) ----------------------------------------------- Loose to medium dense, moist, dark brown, silty SAND with some gravel and fine roots_(Fill) ---_ Medium dense, moist, brown, silty, gravelly SAND (Weathered glacial till) 1 z 5% S-1 3 4 6 13% S-2 Total depth = 6 feet (auger refusal on gravel) No groundwater seepage or caving observed. 7 8 Zipper Zeman Associates Inc. 18905 — 33A Avenue West, Suite 117 Lynnwood, Washington 98036 (425)771 -3304 Zipper Zeman Associates, Inc. M05 -33'd Avenue West, ,Suite 117 Lynnwood, Washington (425) 771 -3304 Hand Au er Borin HA -Z Location: See Figure I Approx. ground surface elevation (feet): 246 Project: Quenzer / Roth Residence Project No.: J-81065103 Date Excavated: 2 August 20.06 Depth (feet) Material Description Ne Moisture Sample Testing 2+ inches of landscaping bark above very loose, wet, gray -brown, gravelly SAND (Fill) ---------------------------------- Very loose to loose, damp to moist, gray -brown, fine to medium SAND with trace coarse sand and fine gravel (Fill) ----------------------------------------------- Loose, wet, dark brown, silty SAND with fine organic material and roots (Relic topsoil) Veit' stiff, wet, mottled gray -brown, fine sandy SILT 1 2 14 S-1 3 4 5 4 6 7 24 S-2 Total depth = 7 feet No groundwater seepage or caving observed. S Zipper Zeman Associates, Inc. M05 -33'd Avenue West, ,Suite 117 Lynnwood, Washington (425) 771 -3304 APPENDIX B LABORATORY TESTING PROCEDURES AND RESULTS APPENDIX B LABORATORY TESTING PROCEDURES Project No.: 81065] 03 A series of laboratory tests were performed during the course of this study to evaluate the index and geotechnical engineering properties of the subsurface soils. Descriptions of the types of tests performed are given below. Visual Classification Samples recovered from the exploration locations were visually classified in the field during the exploration program. Representative portions of the samples were carefully packaged in moisture tight containers and transported to our laboratory where the field classifications were verified or modified as required. Visual classification was generally done in accordance with the Unified Soil Classification system. Visual soil classification includes evaluation of color, relative moisture content, soil type based upon grain size, and accessory soil types included in the sample. Soil classifications are presented on the exploration logs in Appendix A. Moisture Content Determinations Moisture content determinations were performed on representative samples obtained from the explorations in order to aid in identification and correlation of soil types. The determinations were made in general accordance with the test procedures described in ASTM: D-2216. The results are shown on the exploration logs in Appendix A.