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HomeMy WebLinkAbout03076 - Technical Information Report - Geotechnical Zipper Zeman Associates, Inc. Geotechnical and Environmental Consulting J-1177 November 1, 2041 City of Renton Renton City Hall— 5`h Floor Renton, Washington 98055 Attention: iVls. Tracy Coleman Capital Project Coordinator Subject: Report of Geotechnical Services Proposed Fire Station 1209 Kirkland Avenue NE Renton, Washington Dear Ms. Coleman, Zipper Zeman Associates, Inc. (ZZA) has completed a geotechnical evaluation for the proposed Fire Station at 1209 Kirkland Avenue iVE in Renton, Washington. This report presents the results of our geotechnical evaluation relative to design and general construction considerations. Authorization to proceed with this evaluation was provided through the contract agreement between the City of Renton and Zipper Zeman Associates, Inc. dated September 21, 2001. The field evaluation was completed on October 1, 2001. We understand that the project is in the early planning stages, with the fire station building currently planned to be located in the central or southern portion of the property. The fire station will consist of a one to ttvo story structure, with a possible basement. Portland concrete and asphalt concrete pavements are anticipated around the station for fire truck and emergency vehicle access, and for general parking areas. The purpose of our geotechnical evaluation is to assess subsurFace conditions relative to the design and construction of the fire station. The scope of our services included an exploration program consisting of excavating seven test pit explorations at the site. Based on the subsurface conditions observed in the test pits, we performed geotechnical analyses and formulated recommendations that are presented in this report. Specific items addressed in this report include: 1. Description of the project site with exploratory locations shown on a site plan; Gi7r pF RE`.TJ�, 2. General subsurface conditions; R E C E I V E D I 3. Earthwork and site preparation recommendations; ��P � � 20�2 � �U'L�'NG D�VISION ' 18905—33rd Avenue W.,Suite 117 Lynnwood,Washington 98036 (425)77l-3304 i Proposed Fire Station J-1177 Renton, Washington November 1,2001 Page 2 4. Structural fill and the suitability of on-site soils for use as structural fill; 5. Recommendations relative to the construction of shallow spread footing foundations and slab-on-grade floors; 6. Recommended lateral earth pressures for subgrade (basement) walls and retainin� walls; 7. Preparation of pavement subgrades; 8. Wet weather construction considerations; 9. Erosion control and site drainage considerations; 10. General seismicity and liquefaction potential; 1 l. Implications of elevator shaft installation; 12. Recommendations for further study, if appropriate. SITE DESCRIPTION The proposed fire station site is located on the north side of NE 12`h Street, between Jefferson Avenue and Kirkland Avenue NE. The site consists of 6 lots encompassing approximately 1.22 acres. The site slopes down to the south with an estimated relief on the order of 10 feet. Most of the property is covered with asphalt. A portion of the ground surface in the south-central area is dirt covered where a previous structure has been removed from the property. FIELD EXPLORATION The subsurface exploration program conducted for this study consisted of completing seven test pit explorations at the site on October 1, 2001. The approximate locations of the test pits are presented in Figure l, Site and Exploration Plan. The test pit explorations were completed to depths ranging from 12 to 15 feet below the existing ground surface. Logs of the test pits are enclosed with this report. Subsurface Conditions In general, subsurface conditions in the test pits were fairly consistent. Test pits TP-1 through TP-6 were located in areas covered with asphalt. Test pit TP-7 was located in the western portion of the removed structure. The asphalt and underlying base course (fill), where present, extended to depths ranging from approximately 0.2 to 0.5 feet. Other fill consisting of loose to dense sand with variable silt and gravel was observed in test pits TP-1, TP-5, TP-6, and ' Zi�per Zeman Associates,Inc. 18905—33rd Avenue W.,Suite ]l7 Lynnwood,Washington 98036 (425)7?1-3304 Proposed Fire Station J-1177 Renton,Washington November 1. �'001 Page 3 TP-7. Some concrete debris and boulders were observed in the fill in test pit TP-6. The fill extended to depths ranging between 1 foot and 2 feet in these test pits. Native glacial till consisting of dense to very dense silty sand with gravel was observed below the asphalt in test pit TP-4, located in the northwest portion of the site, which is higher in elevation than the rest of the site. The glacial till extended to a depth of approximately 5 feet. Below the asphalt, fill, and native glacial till was native sand with minor to some silt and variable gravel. The gravel content generally increased with depth where observed. These sands typically were in a medium dense to dense condition and extended to the bottom of the test pits. Soil descriptions presented in this report are based on the subsurface conditions observed at the specific test pit locations. Variations in subsurface conditions may exist between the exploration locations, and the nature and extent of variations between the explorations may not become evident until construction. If variations then appear, it may be necessary to reevaluate the recommendations presented in this report. Groundwater No groundwater or seepage zones were observed in the test pits at the time of excavation. It should be noted that groundwater conditions and soil moisture contents are expected to vary ' with changes in season,precipitation, site utilization, and other on- and off-site factors. Zones of perched water may tend to develop above the relatively impermeable glacial till and silty zones within the native sand during periods of wet weather. CONCLUSIONS AND RECOMMENDATIONS � Based on the subsurface exploration program, the project appears feasible utilizing conventional shallow foundation support. The following recommendations have been prepared for the design and construction of conventional spread footing foundations and concrete slab-on- grade floors. Site Preparation We anticipate that cuts on the order of 10 feet will be required to establish the finish floor elevation for the planned basement. Site preparation should include the removal of asphalt, existing fill, and organic soils, if encountered, and any other deleterious debris from building and paving areas, or those locations where "structural fill" is to be placed. Exposed soils following site preparation should consist of the native medium dense to dense sand or the dense to very � dense glacial till. Any excavations that extend below finish grades should be backfilled with structural fill as outlined subsequently in this report. Preparation for site grading and construction should include procedures intended to drain ponded water and control surface water runoff. It may not be possible to successfully utilize on- ' Zi�per Zeman Associates, Inc. 18905—33`°Avenue W.,Suite 117 Lynnwood,Washington 98036 (425)77]-3304 Proposed Fire Station J-1177 Renton, Washington November 1, 2001 Page 4 site soils as "structural fill" if accumulated water is not drained prior to grading, or if drainage is not controlled during construction. Attempting to grade the site without adequate drainage control measures will reduce the amount of on-site soil effectively available for use, increase the amount of select import fill materials required, and ultimately increase the cost of the earthwork and foundation construction phases of the project. After removal of pavement, existing fill and other deleterious material, and prior to placement of structural fill, we recommend that foundation and floor subgrade areas, pavement areas, and areas to receive structural fill be proofrolled and compacted to a firm and unyielding condition in order to achieve a minimum compaction level of 92 percent of the modified Proctor m�imum dry density as determined by the ASTM:D-1557 test procedure. Proofrolling should be accomplished with a heavy compactor, loaded double-axle dump truck, or other heavy equipment under the observation of a representative from our firm. The need for or advisabiliry of proofrolling due to soil moisture conditions should be determined at the time of construction. We recommend that a representative from our firm observe the soil conditions prior to and during proofrolling to evaluate the suitability of stripped subgrades. Excavated site soils may not be suitable for use as structural fill depending on the moisture content and weather conditions at the time of construction. If soils are stockpiled for future reuse and wet weather is anticipated, the stockpile should be protected with plastic sheeting that is securely anchored. If on-site soils become unusable, it may become necessary to import clean, granular soils to complete wet weather site work. Subgrade soils that become disturbed due to elevated moisture conditions should be overexcavate d to expose firm, non-yielding, non-organic soils and backfilled with compacted structural fill. We recommend that the earthwork portion of this project be completed during extended periods of dry weather, if possible. If earthwork is completed during the wet season, it I may be necessary to take extra precautionary measures to protect subgrade soils. Wet season �I earthwork may require additional mitigative measures beyond that which would be expected during the drier summer and fall months. This could include diversion of surface runoff around exposed soils, draining of ponded water on the site, and collection and rerouting of groundwater seepage from upgradient on- and off-site sources. Once subgrades are established, it may be necessary to protect the exposed subgrade soils from construcrion traffic. Placing quarry spalls, crushed recycled concrete, or clean pit-run sand and gravel over these areas would help protect the soils from construction traffic. Structural Fill All fill material placed in building, pavement, and non-landscaped areas should be placed as structural fill. Prior to placement, the exposed subgrade surfaces to receive structural fill should be prepared as previously described. All structural fill should be free of organic material, debris, or other deleterious material. Individual particle size should be less than 3 inches in maximum dimension. ' Zipper Zeman Associates, Inc. I8905—33rd Avenue V4'.,Suite I I7 Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-11i7 Renton,Washington November 1,2001 Page� , Structural fill should be placed in lifts no greater than 8 inches in loose thickness. The structural fill should be compacted to at least 95 percent of the modified Proctor maximum dry density as determined by the ASTM:D-1557 test procedure in building areas and to a depth of 2 feet below the subgrade surface in pavement areas. Below a depth of 2 feet in pavement areas, the structural fill should be compacted to at least 90 percent of ASTM:D-1557. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with current local codes and standards. The suitability of soils for use as structural fill 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 10 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 rnore than a few percent from optimum. The optimum moisture content is that which yields the greatest soil density under a given compactive effort. The native sand observed in the test pits generally appears suitable for use as structural fill. However, the glacial till observed in test pit TP-4 (to a depth of approximately 5 feet), and ' the native silty sands (in the upper 1 to 2.5 feet in test pits TP-1, TP-2, and TP-6) contain a significant fine-grained fraction. Consequently, use of these soils as structural fill will require that strict control of moisture content be maintained during the grading process. Soil moisture conditions should be expected to change throughout the year. Drying of over-optimum moisture soils may be achieved by scarifying or windrowing su�cial materials during extended periods of dry weather. Soils which are dry of optimum may be moistened through the application of water and thorough blending to facilitate a uniform moisture distribution in the soil prior to compaction. In the event that inclement weather or wet site conditions prevent the use of on-site soil or non-select material as structural fill, we recommend that a "clean", free-draining pit-run sand and gravel be used. Such materials should generally contain less than 5 percent fines, based on that soil fraction passing the U.S. No. 4 sieve, and not contain discrete particles greater than 3 inches in maximum dimension. 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. We recommend that site grading and earthwork be scheduled for the drier months, if at all possible. Permanent Fill Slopes � Permanent fill slopes should be constructed no steeper than 2H:1 V. If the slopes are exposed to prolonged rainfall before vegetation becomes established, the surficial soils will be prone to erosion and possible shallow sloughing. Surficial repairs, such as protecting affected ' Zipper Zeman Associates, Inc. 1890�-33`°Avenue�V.,Suite l U Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton,Washington November 1,2001 Page 6 areas with quarry spalls, jute matting or other system, may be necessary until vegetation is established. Temporary and Permanent Cut Slopes Temporary slope stability is a function of many factors, including the following: 1. The presence and abundance of groundwater; 2. The type and density of the various soil strata; 3. The depth of cut; 4. Surcharge loadings adjacent to the excavation; 5. The length of time the excavation remains open. It is exceedingly difficult under the variable circumstances to pre-establish a safe and "maintenance-free" temporary cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. It may be necessary to drape temporary cut slopes with plastic or to otherwise protect the slopes from the elements in order to minimize sloughing and erosion. We do not recommend unsupported vertical cuts deeper than 4 feet if worker access is necessary. The cuts should be adequately sloped or supported to prevent injury to personnel from local sloughing and spalling. The excavation should conform to applicable Federal, State, and local regulations. For preliminary planning purposes only, temporary cuts in the fill and upper 3 to 4 feet of native sand will likely require slopes of 2H:1 V or flatter to reduce the potential for sloughing. The medium dense to dense sand observed at depth in the test pits is anticipated to maintain cut slopes on the order of 1 H:1 V. For all cut slopes, if seepage or surface runoff occurs and is not controlled, flatter temporary slopes may be necessary. These guidelines assume that surface loads, such as equipment loads and storage loads, will be kept a sufficient distance away from the top of the cut so that the stability of the excavation is not affected. For medium dense to very dense native soils, or compacted structural fill, we generally recommend all permanent cut slopes be designed at a 2H:1V inclination or flatter. It has been our experience that permanent slopes steeper than 2H:1 V will tend to ravel and slough to a flatter inclination over time. In addition, with the steeper slopes, topsoil erodes readily and it is more difficult and takes longer to establish vegetation for slope protection. Foundations All footings should be founded on the medium dense to dense native sand, glacial till, or on compacted structural fill that extends down to these competent native soils. Footings should not be founded on or within loose or disturbed native soil or fill unless it has been evaluated and ' Zi�per Zeman Associates, Inc. 18905—33rd Avenue W.,Suite i 17 Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton, Washington November 1,2001 Page 7 approved by the geotechnical engineer. Continuous or column footings may be designed for a maximum allowable bearing pressure of 3,000 psf. A one-third increase in this bearing pressure may be used for short-term wind or seismic loading. Exterior footings should extend at least 18 inches below adjacent grade for frost protection, while interior footings should extend at least 12 inches below adjacent grade. We recommend that all continuous and isolated footings be at least 18 and 24 inches in width, respectively. We estimate that the total settlement of foundation members founded within the medium dense to dense sand, glacial till, or structural fill prepared as described above may approach 1 inch. Differential settlement of foundations founded within the same soil type could approach %2 inch over a distance of 30 feet. Settlements would occur elastically as the loads are applied. Foundation settlement is oftentimes a function of the condition of the footing excavation subgrade. Under no circumstances should footings be cast atop loose or soft soil, slough, debris, or surfaces with standing water. We recommend that a representative from our firm observe the condition of the footing subgrades prior to pouring footing concrete in order to confirm that the bearing soils are undisturbed and that conditions are consistent with the recommendations contained within this report. We recommend that perimeter footing drains with cleanouts be installed around the planned building. The drains should consist of a minimum 4-inch diameter perforated pipe I embedded in at least a 24-inch wide envelope of clean, free-draining granular material containing I, less than 5 percent fines (material passing the U.S. No. 200 sieve). Footing drains should be directed toward appropriate storm water drainage facilities and not onto adjacent slopes. Roof drains should not be connected to the footing drains. We recommend that the ground surface adjacent to foundations be sloped to drain surface runoff away from the structure. Slab-On-Grade Floors Slab-on-grade floor subgrades should be prepared in accordance with the site preparation recommendations presented above. All slab-on-grade floors should be founded on the medium dense to dense native sand, glacial till, or on compacted structural fill extending down to these competent native soils. Slab-on-grade floors should not be founded on or within loose or dishubed native or fill soil unless it has been evaluated and approved by the geotechnical engineer. We recommend that at least 4-inches of clean coarse sand and gravel (containing less than 5 percent material passing the U.S.No. 200 sieve) be placed between the prepared subgrade and bottom of the concrete floors. This zone will serve for support, and as a capillary break and working surface. In floor slab areas where moisture sensitive floor coverings are planned, an impermeable membrane (e.g. polyethylene sheet) should be placed directly beneath the floor slab to act as a vapor barrier. The impermeable membrane should be protected by two inches of fine, moist sand placed both above and below the membrane. The sand cover will provide protection for the ' Zipper Zeman Associates, Inc. 18905—33nd Avenue W.,Suite 117 Lynnwood,Washington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton,VVashington November 1,2001 Page 8 membrane and will promote uniform curing of the concrete slab. The sand cover should be moistened and tamped prior to slab placement. For basement and other below grade floors, we recommend that an underslab drainage system be installed below the new floor slabs. The underslab drainage system should consist of at least 12 inches of structural fill consistina of free-draining (less than 3 percent fines) coarse sand and gravel. To discharge water which tends to collect in the zone of structural fill, we recommend that a system of 4-inch diameter perforated drainage pipe be installed in trenches which extend below the zone of free-draining structural fill. These trenches should be at least 12 inches deep and backfilled with the free-draining coarse sand and gravel. The perforated drainpipe should have a maximum center-to-center spacing of 25 feet and should be sloped to drain to a suitable discharge. Cleanouts should be provided for the perforated drainpipe. Backfilled Walls/Lateral Earth Pressures All backf'ill placed behind retaining or basement walls should be placed as structural fill compacted to a minimum of 92 percent of the maximum dry density per ASTM D-15�7. The compactive effort should be increased to 95 percent where settlement sensitive facilities are supported on the wall backfill. To minimize lateral earth pressures and prevent the buildup of hydrostatic pressures, the backfill within 24 inches of the wall should contain less than 5 percent fines, based on that portion passing the U.S. No. 4 sieve, coupled with a perforated pipe drain placed at the base of the wall backfill, similar in configuration to that described for the perimeter footings. The upper 1-foot of the wall backfill should consist of low permeability silty soii and the ground surface should be sloped away from the wall in order to reduce the potential for surface water infiltration behind the wall. The following recommended lateral earth pressures, presented as equivalent fluid densities, are based on the assumption of a relatively level backfill (slopes of 4H:1V, or flatter) with no buildup of hydrostatic pressure behind the wall. 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 density of 55 pounds per cubic foot (pc�. If the top of the wall is free to move laterally in an amount equal to at least 0.1 percent of the wall height, they may be designed for an "active" equivalent fluid density of 35 pcf. For building and retaining wall foundations, we recommend using an allowable base friction value of 0.35. Passive resistance for foundations embedded at least 18 inches below finish grades may be computed using an allowable equivalent fluid density of 250 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 behind the walls is level and compacted to approximately 92 percent of the modified �' Proctor(ASTM D-1557) maximum dry density. Additional compaction adjacent to the wall will I increase the earth pressure, while a lesser degree of compaction could result in post construction �� settlements. ' Zipper Zeman Associates, Inc. 18905—33`'Avenue W.,3uite 11? Lynnwood,1Vashington 98036 (425)i i 1-3304 Proposed Fire Station J-11 i7 Renton,Washington November l,2001 Page 9 Utility trenches may act as a oundwater conduits by intercepting perched groundwater seepage. Some of these utility trenches may lead to the proposed building. Therefore, it is highly recommended that the wall backfill consist of free-draining aggregate as recomrnended above. Additionally, footing drains should be constructed at elevations below all wall penetrations and preferably at footing elevations. These drains should be connected to an approved storm water discharge receptor. Seismic Criteria Figure 16-J in the 1997 Uniform Building Code classifies the subject site as being within Seismic Zone 3. Based on the subsurface conditions encountered at the site and published geologic literature, it is our opinion that Soil Profile Type S� should be used to describe the average soil properties within the upper 100 feet beneath the site. This designation describes soils that are considered very dense with a shear wave velocity of 1,200 to 2,500 feet per second, Standard Penetration Test values greater than 50, and an undrained shear strength greater than 2,000 psf. Soil liquefaction is a condition where loose, saturated granular soils loose strength during the ground shaking associated with an earthquake. No groundwater was encountered at the site to the bottom of the test pit excavations. In addition, the soils encountered in our test pits typically consisted of glacial till or medium dense to dense sand. The risk of liquefaction at the site is considered low due to the lack of groundwater and the overall condition of the native soils. Erosion Control Erosion and sedimentation controls are recommended during construction to reduce the potential impacts to adjacent areas. Erosion control measures should be designed to prevent sediment transport. This may be accomplished by constructing water bars or utilizing other methods to control surface water runoff, and constructing silt fences to control sedimentation. If construction is accomplished during the winter months, we further recommend that temporary erosion protection be provided consisting of covering exposed soil areas with plastic sheeting, jute matting, and/or straw. We recommend that all bare soil areas be planted or mulched as soon as possible. It may be necessary to provide temporary erosion protection until vegetation has been reestablished. Pavements The native medium dense to dense sand and glacial till are considered suitable for subgrade support of pavements. We recommend that the subgrade in pavement areas be prepared as recommended in the Site Preparation section of this report. The upper one-foot of � pavement subgrade soils should be compacted to at least 95 percent of the maximum dry density I Zipner Zeman Associates, Inc. 18905—33rd Avenue�'V.,Suite 117 Lynnwood,Washington 98036 (4?5)771-330�4 Proposed Fire Station J-1177 Renton, Washington November 1, 2001 Page 10 determined in accordance with the ASTM D-1557 test method. The extent of any soil improvement or replacement can only be determined at the time of construction. Finished subgrade surfaces should be constructed to facilitate drainage and prevent ponding of water below the pavement section. We recommend that a layer of crushed base course be placed between the prepared subgrade or structural fill, and the pavement working surface material (asphalt or concrete). Base course material under Portland concrete and asphalt pavement should conform to Specification 9-03.9(3) of the WSDOT/APWA 2000 Standard Specifications, or current City of Renton or King County standards. Base material should be moisture conditioned and compacted to a minimum of 95 percent of the maximum dry density per ASTM D-1557. Other Considerations We understand that an elevator for the new fire station facility may be considered. The elevator shaft may extend below the depth explored in our test pits. It is unknown if groundwater might be encountered within the limits of the elevator shaft. We recommend that the installation of the elevator shaft be monitored by a representative from our firm to assess if any special measures are necessary to deal with groundwater encountered in the drilled elevator shaft hole. We understand that on-site stormwater disposal systems may be considered at the site. In I��! general, the lack of a permanent shallow groundwater table, and the granular nature of the native '� soils observed in the test pits appear to suggest that some on-site infiltration may be feasible. ' However, we recommend that required soil infiltration testing per City of Renton and/or King , County Stormwater standards be performed to assess appropriate infiltration rates used in the design of on-site stormwater disposal systems. We recommend that any additional subsurface testing be performed in the immediate area of the planned infiltration system(s). CLOSURE This report has been prepared in accordance with generally accepted geotechnical engineering practices for the exclusive use of the City of Renton for specific application to the planned fire station at 1209 Kirkland Avenue NE in Renton, Washington. The conclusions and recommendations presented in this report are based on the explorations accomplished for this study. The number, location, and depth of the explorations were completed within the site and scope constraints of the project so as to yield the information necessary to formulate our recommendations. The plans for this project were in the preliminary stage at the time this report was written. Under the circumstances, it is recommended that we be provided the opportunity for general review of the, project plans and specifications in order to confum that the recommendations and design considerations presented in this report have been properly interpreted and implemented into the project design package. Zipper Zeman Associates, Inc. I8905—33rd Avenue W.,Suite 1 l7 Lynnwood,�V�shington 98036 (425)771-3304 Proposed Fire Station J-1177 Renton,Washington November 1,2001 Page 11 The integrity and performance of foundation systems depend greatly on proper site preparation and construction procedures. Field judgement by a qualified engineer will be necessary in order to determine the adequacy of the site drainage and foundation support systems. Therefore, because of our familiarity with the site soils, we recommend that Zipper Zeman Associates, Inc. be retained to provide geotechnical engineering services during earthwork and foundation construction of the fire station. If variations in the subsurface conditions are observed at the time of construction, we would be able to provide additional geotechnical engineering recommendations to the contractor and owner in a timely manner as the project construction progresses. We appreciate this opportunity to be of service to you, and would be pleased to discuss the contents of this report or other aspects of the project with you at your convenience. Respectfully submitted, Zipper Zeman Associates, Inc. w o Tx�r� � �/1�'" ��� F tVA$� cASO �s s , e � ti � � � °� Timothy H. Roberts, P.E., P.G. `-�:, Project Engineer r 19409 ,�4 �"�`�FecSTE��'���� L Sf�iV AL �� �,,.r—'� t� S EXPIRES 4/3/2402 ; James B. Thompson, P.E. Principal � i Enclosures: Figure 1 —Site and Exploration Plan Test Pit Logs (TP-1 through TP-7) ;- � � . i � � , �-�, I I '� Zipper Zeman Associates, Inc. 18905—33rd Avenue W.,Suite 117 Lynnwood,�Vashington 98036 (425)7'(-3304 i N.E. 13TH STREET i � ' TP-4 ui Z TP- W W ' z Q w I > � TP-2 �❑ � TP-5 zQ � w � W TP-7 Y � —� Y � TP-1 � TP-6 � N.E. 12TH STREET m ' a I z I EXPLANATION �TP-6 p ?00 200 ZZA TEST PIT NUMBER AND APPROXIMATE LOCATION SCALE IN FEET Zipper Zeman AssoCiates,Inc. Project No.J-1177 Renton Fire Station Geotechnicat and Environmental Consulting Date:October 2001 City of Renton Drawn by:SCK Washington 18905 33rd Avenue West,Suite 117 Scale:As Noted Lynnwood,VVashington 98036 FIGL'RE 1 -SITE AND EXPLORATION PLAN Tele:(425)771-3304 Fax:(425)771-3549 Renton Fire Station J-11i7 Renton, WA Tzst Pit Log Pa�e 1 Test Pit TP-1 Depth (feet� Material Description 0.0-0.3 2" Asphalt over base course (Fill) 0.3-1.3 Dense, damp, dark brown, silty SAl'�1D with gravel. (Fill) 1.3-2.0 Medium dense to dense, damp, orange-brown, silty SAND with occasional gravel. 2.0-5.5 Medium dense, damp, gray, fine to medium SA:�1D with minor silt. 5.5-14.0 Medium dense to dense, damp to moist, gray-brown, gravelly SAND to sandy GRAVEL. Test pit completed at 14.0 feet on 10/1/O1. No groundwater seepage observed. No caving observed. Test Pit TP-2 Depth �feet) Material Description 0.0-0.5 2"Asphalt over base course (Fill) 0.5-1.5 Medium dense, damp, orange-brown, silty SAND with gravel. 1.5-2.75 Medium dense to dense, damp, gray, SAND. 2.75-4.5 Medium dense, damp, gray, fine to medium SAND with minor silt. 4.5-6.5 Medium dense to dense, damp, gray-brown, gravelly SAND with occasional cobbles. 6.5-13.5 Medium dense to dense, damp to moist, fine to medium SAND with minor silt. Test pit completed at 13.5 feet 10/1/O1. No groundwater seepage observed. No caving observed. � . Renton Fire Station J-1177 Renton, WA Test Pit Log Page 2 Test Pit TP-3 Depth(feet) Material Description 0.0-0.3 2 '/2"Asphalt over base course (Fill) 0.3-15.0 Medium dense, damp, gray-brown, fine to medium SAI�D with minor silt. Test pit completed at 1�.0 feet on 10/1/O1. No groundwater seepage observed. No caving observed. Test Pit TP-4 Depth (feet) Material Description 0.0-0.2 Asphalt 0.2-0.8 Dense, damp, brown, silty SAND with gravel. (Till) 0.8-5.0 Dense to very dense, damp, gray-brown, silty SAND with gravel. (Till) 5.0-12.0 Dense, damp, gray-brown, fine to medium SAND with minor silt. Test pit completed at 12.0 feet on 10/1/O1. No groundwater seepage observed. No caving observed. � Renton Fire Station J-1177 Renton, WA Test Pit Log Page 3 Test Pit TP-5 Depth (feet) Material Description 0.0-0.2 Asphalt 0.2-1.0 Medium dense, damp, brown, silty SAND with gravel. (Fill) 1.0-3.75 Medium dense to dense, damp, gravelly SAlvD with some silt. 3.75-13.0 Medium dense to dense, damp, gray-brown, fine to medium SAND with occasional cobbles. Test pit completed at 13 feet on 10/1/O1. No groundwater seepage observed. No caving observed. � ' Test Pit TP-6 Depth(feet) Material Description 0.0-0.2 Asphalt 0.2-2.0 Medium dense; damp,brown, silty SAND with gravel, concrete debris, boulders. (Fill) 2.0-2.5 Medium dense, damp, orange, silty SAND. 2.5-5.0 Medium dense to dense, damp, gray, gravelly SAND with minor silt. 5.0-5.5 Medium dense to dense, damp,brown, silty SAND. 5.5-14.0 Medium dense to dense, damp, gray-brown, fine to medium SAND with minor silt. Test pit completed at 14.0 feet on 10/1/O1 No groundwater seepage observed. No caving observed. Renton Fire Station J-1177 Renton, WA Test Pit Log Page 4 Test Pit TP-7 Depth (feet� Material Description 0.0-1.� Loose, damp, brown, silty S�ND with gravel. (Fill) 1.5-15.0 l�ledium dense to dense, damp, gray-brown, fine to medium SAND with minor silt. Test pit completed at 15.0 feet on 10/1/O1. No groundwater seepage observed. No caving observed. � I