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HomeMy WebLinkAboutSWP272258(2) O E O T E C H March 5, 1996 CONSULTANTS, INC- 1:3256 N.E.20th St.(Nor[hup\1a>).Suite 16 JN 96036 Bellevue,OVA 98005 (206)747-5618 FAX 747-8561 Anderson Richardson Company 300 - 120th Avenue Northeast Building 2, Suite 217 Bellevue, Washington 98005 Attention: Douglas Richardson Subject: Geotechnical Engineering Study Proposed Springside Building Southwest 39th Street at Springbrook Creek Renton, Washington Dear Mr. Richardson: We are pleased to present this geotechnical engineering report for the Springside building to be constructed in Renton, Washington. The scope of our work consisted of exploring site surface and subsurface conditions, and then developing this report to provide recommendations for general earthwork and design criteria for foundations, retaining walls, and pavements. You authorized our work by accepting our proposal, P-3793, dated January 30, 1996. The subsurface conditions of the proposed building site were explored with three test borings that revealed loose, alluvial silt and silty sand beneath the existing asphalt and 1 to 2 feet of gravelly sand fill. It is our opinion that the proposed structure can be supported on conventional footings placed over at least 2 feet of imported structural fill that bears on the native soil or existing fill. Preloading the site should be necessary only if large slab loads are anticipated or if some noticeable differential settlement in the structure is not allowable. The site soil is typically silty, and it has a relatively high moisture content. Wet weather earthwork should be avoided, if possible. The excavated soil will generally be unusable for structural fill. The existing pavement may experience some distress in heavily loaded truck traffic areas. The attached report contains a discussion of the study and our recommendations. Please contact us, if there are any questions regarding this report or if we can be of further assistance during the design and construction phases of this project. Respectfully submitted, GEOTECH CONSULTANTS, INC. Marc R. McGinnis, P.E. Associate � , 1199 Q17 'IV MRM:jcv OP GEOTECHNICAL ENGINEERING STUDY Proposed Springside Building Southwest 39th Street at Springbrook Creek Renton, Washington This report presents the findings and recommendations of our geotechnical engineering study for the site of the proposed Springside office and warehouse building in Renton. The general location of the site is illustrated on the Vicinity Map, Plate 1. Development of the property is in the planning stage, and detailed plans were not available to us at the time of this report. We were provided with a lot map and a conceptual site plan. A copy of the water plan for the project site was also provided. Based on these plans and discussions with you, we anticipate that the proposed office and warehouse building will have a tilt-up concrete construction. The northern portion of the building will contain the warehouse, and truck loading will occur at the warehouse's northern end. At least part of the warehouse will be built several feet above the existing site grade to create dock-high truck loading. No heavy slab loads are anticipated. We anticipate that the existing pavement will remain around the proposed building for parking and drive lanes. SITE CONDITIONS Surface The site is an irregularly shaped lot situated immediately southwest of the cul-de-sac at the western end of Southwest 39th Street. This property has been used as a parking lot for the adjacent northern Boeing office complex for the last approximately nine years. Most of the site is covered with asphalt paving, and landscaped islands are scattered around the parking lot. Springbrook Creek is located immediately west of a low dike that extends along the western property line. A railroad spur extends along the southern and eastern sides of the site. Respectively east and south of this railroad spur are an asphalt parking lot and a large warehouse. The site is relatively flat, and the provided water plan indicates that the site grades vary between approximately 15 and 16 feet. This plan shows the top of the adjacent western dike to have an elevation of about 18 feet. Our field explorations were conducted after several days of unusually heavy rainfall, and the creek was flowing at an elevation near, or above, the average site grade. We noted that the catch basins for the storm drainage system in the parking lot were full. Water was standing above the rims of several catch basins. The existing asphalt pavement has been subjected to automobile loads, and it appears to have performed relatively well. We do not know if the parking lot has been overlaid in the past. GEOTECH CONSULTANTS,INC. Anderson Richardson Company JN 96036 March 5, 1996 Page 2 Subsurface The subsurface conditions were explored by drilling three borings at the approximate locations shown on the Site Exploration Plan, Plate 2. The field exploration program was based upon the proposed construction and required design criteria, the site topography and access, the scope of work outlined in our proposal, and the time and budget constraints. The borings were drilled on February 8, 1996, using a truck-mounted, hollow-stem auger drill. Samples were taken at 5-foot intervals with a standard penetration sampler. This split-spoon sampler, which has a 2-inch outside diameter, is driven into the soil with a 140-pound hammer falling 30 inches. The number of blows required to advance the sampler a given distance is an indication of the soil density or consistency. A geotechnical engineer from our staff observed the drilling process, logged the test borings, and obtained representative samples of the soil encountered. The Test Boring Logs are attached as Plates 3 through 5. The three test borings revealed generally similar soil conditions below the 3 to 4 inches of asphalt pavement. We found a thin layer of crushed rock beneath the asphalt, and 1 to 2 feet of gravelly, slightly silty to silty sand fill beneath the crushed rock. This fill was loose to medium-dense and appeared to have been at least moderately compacted. The native soil beneath the fill consisted of loose to medium-dense silt and silty sand. Silt and sand have been deposited in the Kent/Renton Valley over a long period of time by the Green River and other watercourses that have flowed into the valley. We also encountered occasional thin lenses of organics and peat within the alluvial deposits. The final logs represent our interpretations of the field logs. The stratification lines on the logs represent the approximate boundaries between soil types at the exploration locations. The actual transition between soil types may be gradual, and subsurface conditions can vary between exploration locations. The logs provide specific subsurface information only at the locations tested. If a transition in soil type occurred between samples in the borings, the depth of the transition was interpreted. The relative densities and moisture descriptions indicated on the test boring logs are interpretive descriptions based on the conditions observed during drilling. Groundwater Groundwater seepage was immediately below the asphalt pavement in two of the three borings, and we encountered groundwater seepage at a depth of 2 feet in Boring 3. As discussed above, the level of Springbrook Creek was near the existing site grades at the time of our borings, and this likely caused the extremely high water levels observed during our field work. Water levels in the Kent/Renton Valley are typically found at a depth of 5 to 10 feet, depending on the time of year and the amount of recent rainfall. Groundwater levels below the site will be influenced by the level of Springbrook Creek. CONCLUSIONS AND RECOMMENDATIONS General Based on our observations and the results of the test borings, it is our opinion that the proposed development is feasible from a geotechnical engineering standpoint. The alluvial soil that is under GEOTECH CONSULTANTS,INC. Anderson Richardson Company JN 96036 March 5, 1996 Page 3 the site is moderately compressible, but it appears that the commercial building can be supported on conventional foundations without first preloading the building pad. The use of conventional foundations assumes that some detectable differential settlement in the walls and floor slabs is acceptable. All footings should be placed on at least 2 feet of imported, gravelly, structural fill placed above the existing fill or native soil that is under the pavement. The asphalt should be removed within the building footprint to expose existing utilities for abandonment and to verify that no overly soft soil is present near the surface. If more that about 2 feet of fill will be placed above the existing grade for the slab areas, the fill should be placed to the subgrade elevation, and then it should be allowed to sit and consolidate the underlying soil for at least one month before slab and foundation construction. Reinforcing the slab floors with steel bars should be considered, if concentrated rack loads will be applied. Preloading should only be necessary if heavy slab loads are anticipated. The relatively high groundwater levels at the site could cause difficulties both during and following construction. We anticipate that groundwater is often near the existing ground elevation during the wet season, and this should be considered in setting final grades within and around the building. The existing storm drainage system, if reused for the proposed project, should be analyzed for adequacy in the event of high groundwater levels. The site soil is generally silty and typically wet. Reusing the excavated soil for structural fill beneath the building, the pavement, or other structural areas will not be feasible. This should be considered in the budget for underground utilities, as the backfill will need to be imported. The silty, on-site soil will be susceptible to softening under equipment traffic. Wet weather earthwork will certainly be more difficult and costly, particularly if groundwater levels are high at the time of utility installation. We anticipate that at least portions of the existing pavement will remain and be incorporated into the new development. The existing pavement appears to have performed well under automobile loading; it appears to consist of at least 3 inches of asphalt concrete over a thin layer of crushed rock and 1 to 2 feet of imported, gravelly sand fill. We anticipate that this pavement will likely perform fairly well under future automobile and truck traffic. Some distress or subgrade softening may be encountered in areas of frequent, repetitive truck traffic, particularly when groundwater levels are near their highest. The existing fill and native soil beneath the pavement are susceptible to softening under heavy traffic loading when they are wet. Geotech Consultants, Inc. should be allowed to review the final development plans to verify that the recommendations presented in this report are adequately addressed in the design. Such a plan review would be additional work beyond the current scope of work for this study, and it may include revisions to our recommendations to accommodate site, development, and geotechnical constraints that become more evident during the review process. Conventional Foundations The proposed structure can be supported on conventional continuous and spread footings bearing on at least 2 feet of imported, gravelly, structural fill placed above the native soil or fill presently beneath the existing pavement. See the later sub-section entitled General Earthwork and Structural Fill for recommendations regarding the placement and compaction of structural fill beneath structures. We recommend that continuous and individual spread footings have GEOTECH CONSULTANTS,INC. Anderson Richardson Company JN 96036 March 5, 1996 Page 4 minimum widths of 16 and 24 inches, respectively. They should be bottomed at least 12 inches below the lowest adjacent finish ground surface for frost protection. The local building codes should be reviewed to determine if different footing widths or embedment depths are required. An allowable bearing pressure of 2,000 pounds per square foot (psf) is appropriate for footings constructed according to the above recommendations. A one-third increase in this design bearing pressure may be used when considering short-term wind or seismic loads. For the above design criteria, it is anticipated that the total post-construction settlement of footings will be about 2 to 3 inches, with differential settlements on the order of 1 inch in a distance of 100 feet along a continuous footing. These anticipated settlements are in the range of typical settlements for other commercial buildings in the area. Lateral loads due to wind or seismic forces may be resisted by friction between the foundation and the bearing soil, or by passive earth pressure acting on the vertical, embedded portions of the foundation. For the latter condition, the foundation must be either poured directly against relatively level, undisturbed soil or surrounded by level, structural fill. We recommend using the following design values for the foundation's resistance to lateral loading: Parameter Design Value Coefficient of Friction 0.35 Passive Earth Pressure 300 pcf Where: 1. pcf is pounds per cubic foot. 2. Passive earth pressure is computed using the equivalent fluid density. If the ground in front of the foundation is loose or sloping, the passive earth pressure given above will not be appropriate. We recommend a safety factor of at least 1.5 for the foundation's resistance to lateral loading, when using the above design values. Seismic Considerations The site is located within Seismic Zone 3 as illustrated on Figure No. 23-2 of the 1991 Uniform Building Code (UBC). In accordance with Table 23-J of the 1991 UBC, the site soil profile is best represented by Profile Type S4. The saturated soil that is under the site is susceptible to seismic liquefaction in a moderate to large earthquake. The liquefaction hazard is reduced by supporting footings on structural fill and designing the structure for Profile Type S4. Slabs-on-Grade The building floors may be constructed as slabs-on-grade atop at least 12 inches of structural fill. The subgrade soil must be in a firm, non-yielding condition at the time of slab construction or underslab fill placement. Any soft areas encountered should be excavated and replaced with select, imported, structural fill. GEOTECH CONSULTANTS,NC. Anderson Richardson Company JN 96036 March 5, 1996 Page 5 All slabs-on-grade should be underlain by a capillary break or drainage layer consisting of a minimum 4-inch thickness of coarse, free-draining, structural fill with a gradation similar to that discussed later in Permanent Foundation and Retaining Walls. In areas where the passage of moisture through the slab is undesirable, a vapor barrier, such as a 6-mil plastic membrane, should be placed beneath the slab. Additionally, sand should be used in the fine-grading process to reduce damage to the vapor barrier, to provide uniform support under the slab, and to reduce shrinkage cracking by improving the concrete curing process. We recommend placing concrete slabs over at least 1 foot of structural fill to provide more uniform support for the slab where the subgrade is soft or settles more rapidly than the surrounding ground. Isolation joints should be provided where the slabs intersect columns and walls. Control and expansion joints should also be used to control cracking from expansion and contraction. Saw cuts or preformed strip joints used to control shrinkage cracking should extend through the upper one-fourth of the slab. The spacing of control or expansion joints depends on the slab shape and the amount of steel placed in it. Permanent Foundation and Retaining Walls Retaining walls backfilled on only one side should be designed to resist the lateral earth pressures imposed by the soil they retain. The following recommended design parameters are for walls that restrain level backfill: Parameter Design Value Active Earth Pressure* 40 pcf Passive Earth Pressure 300 pcf Coefficient of Friction 0.35 Soil Unit Weight 130 pcf Where: 1. pcf is pounds per cubic foot. 2. Active and passive earth pressures are computed using the equivalent fluid densities. For restrained walls that cannot deflect at least 0.002 times their height, a uniform lateral pressure equal to 10 psf times the height of a wall should be added to the above active equivalent fluid pressure. The values given above are to be used to design permanent foundation and retaining walls only. The passive pressure given is appropriate for the depth of level, structural fill placed in front of a retaining or foundation wall only. We recommend a safety factor of at least 1.5 for overturning and sliding, when using the above recommended values to design the walls. The design values given above do not include the effects of any hydrostatic pressures behind the walls and assume that no surcharge slopes or loads, such as vehicles, will be placed behind the GEOTECH CONSULTANTS,INC. Anderson Richardson Company JN 96036 March 5, 1996 Page 6 walls. If these conditions exist, those pressures should be added to the above lateral soil pressures. Also, if sloping backfill is desired behind the walls, we will need to be given the wall dimensions and the slope of the backfill in order to provide the appropriate design earth pressures. The surcharge due to traffic loads behind a wall can typically be accounted for by adding a uniform pressure equal to 2 feet multiplied by the above active fluid density. Heavy construction equipment should not be operated behind retaining and foundation walls within a distance equal to the height of a wall, unless the walls are designed for the additional lateral pressures resulting from the equipment. The compaction of backfill near the walls should be accomplished with hand-operated equipment to prevent the walls from being overloaded by the higher soil forces that occur during compaction. Retaining Wall Backfill Backfill placed behind retaining or foundation walls should be coarse, free-draining, structural fill containing no organics. This backfill should contain no more than 5 percent silt or clay particles and have no gravel greater than 4 inches in diameter. The percentage of particles passing the No. 4 sieve should be between 25 and 70 percent. For increased protection, drainage composites should be placed along cut slope faces, and the walls should be backfilled with pervious soil. The purpose of these backfill requirements is to ensure that the design criteria for a retaining wall are not exceeded because of a build-up of hydrostatic pressure behind the wall. The top 12 to 18 inches of the backfill should consist of a relatively impermeable soil or topsoil, or the surface should be paved. The sub-section entitled General Earthwork and Structural Fill contains recommendations regarding the placement and compaction of structural fill behind retaining and foundation walls. Excavations and Slopes No significant excavated slopes are anticipated other than for utility trenches. Excavation slopes should not exceed the limits specified in local, state, and national government safety regulations. Temporary cuts to a depth of about 4 feet may be attempted vertically in unsaturated soil, if there are no indi:aiions of slope instability. Based upon Washington Administrative Code (WAC) 296, Part N, the soil type at the subject site would be classified as Type C above the groundwater table. Temporary cut slopes that do not encounter seepage should not be excavated at an inclination steeper than 1.5:1 (Horizontal:Vertical), extending continuously between the top and the bottom of a cut. Dewatering, and possibly excavation shoring, will be needed for temporary excavations that encounter groundwater and caving soil. The above-recommended temporary slope inclination is based on what has been successful at other sites with similar soil conditions. Temporary cuts are those that will remain unsupported for a relatively short duration to allow for the construction of foundations, retaining walls, or utilities. Temporary cut slopes should be protected with plastic sheeting during wet weather. The cut slopes should also be backfilled or retained as soon as possible to reduce the potential for instability. Please note that loose, wet soil can cave suddenly and without warning. Utility contractors should be made especially aware of this potential danger. Fill slopes should not be constructed with an inclination greater than 2:1 (H:V). To reduce the potential for shallow sloughing, fill must be compacted to the face of these slopes. This could be GEOTECH CONSULTANTS,INC. Anderson Richardson Company JN 96036 March 5, 1996 Page 7 accomplished by overbuilding the compacted fill and then trimming it back to its final inclination. Water should not be allowed to flow uncontrolled over the top of any temporary or permanent slope. Also, all permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve the stability of the surficial layer of soil. Drainage Considerations We recommend the use of footing drains at the base of footings, where (1) crawl spaces or basements will be below a structure, (2) a slab is below the outside grade, or (3) the outside grade does not slope downward from a building. Drains should also be placed at the base of all backfilled, earth-retaining walls. Footing drains are often needed if loading dock areas are recessed below the surrounding grade. All these drains should be surrounded by at least 6 inches of 1-inch-minus, washed rock and then wrapped in non-woven, geotextile filter fabric (Mirafi 140N, Supac 4NP, or similar material). At its highest point, a perforated pipe invert should be at least as low as the bottom of the footing, and it should be sloped for drainage. All roof and surface water drains must be kept separate from the foundation drain system. A typical drain detail is attached to this report as Plate 6. For the best long-term performance, perforated PVC pipe is recommended for the footing drains. Shallow groundwater was observed during our field work. If seepage is encountered in an excavation, it should be drained from the site by directing it through drainage ditches, perforated pipe, or French drains, or by pumping it from sumps interconnected by shallow connector trenches at the bottom of the excavation. The excavation and site should be graded so that surface water is directed off the site and away from the tops of slopes. Water should not be allowed to stand in any area where foundations, slabs, or pavements are to be constructed. Final site grading in areas adjacent to the building and any retaining structures should slope away at least 2 percent, except where an area is paved. General Earthwork and Structural Fill All building and pavement areas should be stripped of surface vegetation, topsoil, organic soil, and other deleterious material. The existing pavement should be removed in at least the building footprint. The stripped or removed materials should not be mixed with any materials to be used as structural fill, but they could be used in non-structural areas, such as landscape beds. Structural fill is defined as any fill placed under a building, behind permanent retaining or foundation walls, or in other areas where the underlying soil needs to support loads. All structural fill should be placed in horizontal lifts with a moisture content at, or near, the optimum moisture content. The optimum moisture content is that moisture content that results in the greatest compacted dry density. The moisture content of fill is very important and must be closely controlled during the filling and compaction process. The allowable thickness of the fill lift will depend on the material type selected, the compaction equipment used, and the number of passes made to compact the lift. The loose lift thickness should not exceed 12 inches. We recommend testing the fill as it is placed. If the fill is not GEOTECH CONSULTANrS,INC. Anderson Richardson Company JN 96036 March 5, 1996 Page 8 compacted to specifications, it can be recompacted before another lift is placed. This eliminates the need to remove the fill to achieve the required compaction. The following table presents recommended relative compactions for structural fill: Minimum Location of Fill Placement Relative Compaction Beneath footings, slabs, 95% or walkways Behind retaining walls 90% Beneath pavements 95% for upper 12 inches of subgrade, 90% below that level Where: Minimum Relative Compaction is the ratio, expressed in percentages, of the compacted dry density to the maximum dry density, as determined in accordance with ASTM Test Designation D 1557-78 (Modified Proctor). Structural fill that will be placed in wet weather should consist of a coarse, granular soil with a silt or clay content of no more than 5 percent. The percentage of particles passing the No. 200 sieve should be measured from that portion of soil passing the three-quarter-inch sieve. LIMITATIONS The analyses, conclusions, and recommendations contained in this report are based on site conditions as they existed at the time of our exploration and assume that the soil encountered in the borings is representative of subsurface conditions on the site. If the subsurface conditions encountered during construction are significantly different from those observed in our explorations, we should be advised at once so that we can review these conditions and reconsider our recommendations where necessary. Unanticipated soil conditions are commonly encountered on construction sites and cannot be fully anticipated by merely taking soil samples in test borings. Subsurface conditions can also vary between exploration locations. Such unexpected conditions frequently require making additional expenditures to attain a properly constructed project. It is recommended that the owner consider providing a contingency fund to accommodate such potential extra costs and risks. This is a standard recommendation for all projects. This report has been prepared for the exclusive use of the Anderson Richardson Company and its representatives for specific application to this project and site. Our recommendations and conclusions are based on observed site materials, and selective laboratory testing and engineering analyses. Our conclusions and recommendations are professional opinions derived in accordance with current standards of practice within the scope of our services and within budget and time constraints. No warranty is expressed or implied. The scope of our services GEOTECH CONSULTANTS,INC. Anderson Richardson Company JN 96036 March 5, 1996 Page 9 does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractor's methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. We recommend including this report, in its entirety, in the project contract documents so the contractor may be aware of our findings. ADDITIONAL SERVICES In addition to reviewing the final plans, Geotech Consultants, Inc. should be retained to provide geotechnical consultation, testing, and observation services during construction. This is to confirm that subsurface conditions are consistent with those indicated by our exploration, to evaluate whether earthwork and foundation construction activities comply with the intent of contract plans and specifications, and to provide recommendations for design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. However, our work would not include the supervision or direction of the actual work of the contractor and its employees or agents. Also, job and site safety, and dimensional measurements, will be the responsibility of the contractor. The following plates are attached and complete this report: Plate 1 Vicinity Map Plates 3 - 5 Test Boring Logs Plate 2 Site Exploration Plan Plate 6 Footing Drain Detail We appreciate the opportunity to be of service on this project. If you have any questions, or if we may be of further service, please do not hesitate to contact us. 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Q U. \ 5 1.)TH UI �� --_.S 19pTH ST _$ 19)_H$7 1 _. -._.--____ __ 19_2KD ST-I 5-1921iD ST 142!.0 ' -> — G }>— — — — y— 1- q_ —j �j� p — S T _ — 5 19�0 ' S 19:TH ST ; K E T Sl I 19:TH 5T '1 5 1%TH ST VICINITY MAP GEOTECH SW 39th STREET AT CONSULTANTS SPRINGBROOK CREEK RENTON, WA A ✓ob No. Dote Logged BY: P/01e 96036 FEB 1996 1 G�� 00� ,' �B-1 Q• SW 39th STREET Q� 5Q B-3 B-2 PROPOSED OFFICE/ WAREHOUSE 0P LEGEND: APPROXIMATE BORING LOCATIONS SITE EXPLORATION PLAN GEOTECH SW 39th STREET AT CONSULTANTS SPRINGBROOK CREEK RENTON, WA � ✓ob No.� Oote� P/o1e� `�'�' 96036 FEB 1996 2 BORING 1 USCS Description 4" asphalt over crushed rock base FILL Brown, gravelly, silty SAND, wet, loose to medium-dense 1 9 Gray, non-plastic SILT with iron stains and organics, wet, loose 5 2 9 ML -becomes dark gray -grained SAND with peat lenses, wet, Black, slightly silty, fine 10 loose to medium-dense 3 11 I SP 15 SM 4 22 I 20 5 7 -with occasional silt lenses Test boring terminated at 21.5 feet below grade on 2-8-96. 25 Groundwater seepage %vas encountered at 0.5 feet during drilling. 30 35 40 TEST BORING LOG GEOTECH SW 39th STREET AT CONSUI,'CANTS,INc. SPRINGBROOK CREEK � RENTON, WA L9Jobo: Date: Logged by: Plate: 6036 FEB 1996 1 JHS 3 BORING 2 Q '_ 1 egll USCS Description " asphalt over crushed rock base FILL Brown, slightly silty, gravelly, medium-to coarse-grained SAND, wet, medium-dense to dense 1 22 Gray, very silty, very fine-grained SAND with iron stains, very 5 moist, medium-dense 2 14 SM I -becomes mixed with gray silt lenses ML 10 3 3 ML Gray, low plasticity SILT with organics, wet, loose Dark brown, fibrous PEAT, moist, loose -to medium-grained, slightly silty SAND, wet, Black, fine medium-dense 15 4 24 sP S M . 20 -becomes silty with gray silt lenses 5 27 Test boring terminated at 21.5 feet below grade on 2-8-96. Groundwater seepage was encountered at 0.5 feet during drilling. 25 30 35 40 TEST BORING LOG GEOTECH SW 39th STREET AT CONSULTANTS,INC. SPRINGBROOK CREEK RENTON WA Job No. Date: Logged by: Plate: 96036 FEB 1996 JHS 4 °1 BORING 3 Q USCS Description " asphalt over crushed rock base FILL Brown, slightly silty,-gravelly SAND, wet, medium-dense 1 7 I Gray, low plasticity SILT with iron stains, wet, loose 5 2 8 -with organics and some black, silty SAND 10 3 11 I ML -with lenses of organic silt and peat 15 4 g I 20 lack, shtl silty, fine-to medium-grained SAND, wet, 5 24 lffi�!mediumlensye Test boring terminated at 21.5 feet below grade on 2-8-96. 25 Groundwater seepage was encountered at 2 feet during drilling. 30 35 40 TEST BORING LOG GEOTECH SW 39th STREET AT CONSULTANTS,INC. SPRINGBROOK CREEK RENTON WA Job No: Date: Logged by: Plate: 96036 FEB 1996 JHS 5 S/ape bockfi/l away from foundofion. TIGHTL 1NE ROOF DRAIN Do not connect to fooling drain. BACKF/L L See /exl for VAPOR BARRIER requiremen/s. SLAB f WASHED )6m . .o �o• .. '� .� �, ., 4 min. FREE-DRAINING NONWOVEILESAND/GRAVEL FILTER F 4"PERFORATED HARD PVC PIPE Invert 01 Ieo51 as low as fooling and/or crow/ space. Slope /o drain. P/oce weepholes downward. FOOTING DRAIN DETAIL l� GEOTECH SW 39th STREET AT CONSULTANTS SPRINGBROOK CREEK RENTON, WA {{ __ ✓oD No. Dole Scole P/ale 96036 FEB 1996