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HomeMy WebLinkAboutSWP272786(3) '. i .'Report ; \ •Geotechnical Engineeririg Services ,! • ,Proposed.Blackriver.Corporate Park` \ '\ 1 - Ic .Renton, Washington 1998 \c t / ;For Blackri er Rive tech L:L.C. ' WON - SUILDiNC;`DIWtSI j \ . - JUL 0 1 \1998 LPN.Archite'cts.& Planners G e o E n g i n e e r s i L '' r 1 File No.-6063-001-01/06309$ T Y t1r Geo' Engineers July 28, 1998 Consulting Engineers and Geoscientists Offices in Washington, Blackriver River-tech, L.L.C. Oregon,and Alaska c/o Alper Northwest 700 5' Avenue, Suite 6000 Seattle, Washington 98104 Attention: Dean Erickson Supplemental Geotechnical Services Limited Ground Water Evaluation Proposed Blackriver Corporate Park Renton, Washington File Number 6063-001-00, Task 1 INTRODUCTION This letter presents the result of our supplemental geotechnical services to provide further evaluation of ground water levels at the proposed Blackriver Corporate Park in Renton, Washington. Our initial geotechnical findings are presented in our report, "Report, Geotechnical Engineering Services, Proposed Blackriver Corporate Park, Renton, Washington, June 30, 1998." This supplemental ground water evaluation was performed in accordance with our Services Agreement dated June 30, 1998 and authorized by you on July 7, 1998. The supplemental work performed included the following: 1. Review of reports provided by Royce Berg of LPN Architecture & Planning, Inc. and information in our files regarding seasonal ground water levels in the site area. 2. Exploration of ground water levels at the site by excavating three test pits to depths 15 feet below ground surface (bgs) using a rubber-tired backhoe. 3. Presentation of our results based both on observation during test pit excavations and review of previous technical reports in a written technical memorandum. GeoEngineers, Inc, reviewed four previous reports containing information about soil and ground water conditions on or near the site. The reports reviewed included the following: 1. "Geotechnical Engineering Study, Proposed Extended Stay America, Renton Site #418, 1200 Oakesdale Avenue SW, Renton, WA, July 14, 1997," by Geo Group Northwest, Inc. 2. "Geotechnical Engineering Study, Black River Corporate Park, Phase IV, Renton, WA, July 6, 1988," by Earth Consultants, Inc. GeoEn ineers,Inc. Ki:u i 600 Building 600 S:eu;u[St..Sui[e 1215 9S101 �eic'h�;l0ile(206)i 2,S-26 4 F:u(2o6)7 28-27;2 Nvww.geoengineers.coni Printed on recycled OaCer. T T Blackriver Rivertech, L.L.C. July 28, 1998 Page 2 3. "Geotechnical Engineering Study, Black River Corporate Park, Phase VI, Oakesdale Avenue Southwest and Grady Way, Renton, WA, December 31, 1990," by Earth Consultants, Inc. 4. "Report, Geotechnical Engineering Services, Proposed Blackriver Corporate Park, Renton, WA, June 30, 1998," by GeoEngineers, Inc. CONCLUSIONS Information available from the aforementioned reports demonstrated on average that ground water levels on or near the site were at approximately Elevation 8.0 feet based on the New City of Renton Vertical Datum which is equivalent to the North American Vertical Datum of 1988 (NAVD 1988). Water levels were reported for the months of June, November and December with only negligible seasonal differences due to ground water fluctuations noted in the reports. Additionally, GeoEngineers, Inc. recently completed three test pits at the site to evaluate ground water levels during the summer months. Ground water was encountered at depths of 12 to 14 feet bgs (about Elevation 5, 6 and 8 feet in the three test pits). The three test pit locations are shown on the attached site plan. These ground water elevations are about 3 to 4 feet lower than those encountered in the immediately adjacent test pits complete by GeoEngineers on December 17, 1997. We trust this provides the information you require at this time. We appreciate the opportunity to be of continued service to you on this project. Please contact us should you have any questions concerning our findings, or should you require additional information. R e,fully suhmltte'],� GegEnQ' eersr`Inc'. , Bo.Nlc ad Project Manager ht\tB:]JM:pb Document ID: P:\Fl3NALS\606300100L.D0C Attachments Two copies submitted cc: Royce Berg LPN Architecture R. Planning, Inc. 1535 Fourth Avenue South, Suite D Seattle, Washington 98134 G e o E n g i n e e r s File No. 6063-001-00-1130 ~fixa V - . lA "FY-*r� —-—-—-—-—- XY Ulu" ................J. • ------ 4. WV, X.: CN e4 TP-4 Ip k ts. TP-7 TP-3 7: TIP—I B-3 TIP— OA"iAtr r. TP-9 EXPLANATION: + BORING 0 120 240 TP-1�- TEST PIT • SCALE IN FEET SITE PLAN Note: The locations of all features shown are approximate. GeoLEngineerS ,gton7 FIGURE 2 Reference: Drawing entitled Site Plan. Alper Northwest, elockriver Corporate Park, Renton. Weshin by Ipn Architecture and Planning. dated 08/30/97. r Y Geo tzoEnoneers June 30, 1998 Consulting Engineers and Geoscientists Blackriver Rivertech L.L.C. Offices in Washington, 700 5th Avenue, Suite 6000 Oregon,and Alaska Seattle, Washington 98104 Attention: Dean Erickson We are pleased to present three copies of our "Report, Geotechnical Engineering Services, Proposed Black-river Corporate Park, Renton, Washington." Our services were completed in general accordance with the scope of services presented in our proposal dated December 8, 1997. Our services were authorized by you on December 8, 1997. Portions of the results of our study were provided as our conclusions and recommendations were developed, and discussed at a project team meeting at the office of LPN Architecture and Planning, Inc. on June 16, 1998. We appreciate the opportunity to be of service to you on this project. Please call us if you have any questions regarding the contents of this report or when we may be of assistance during the construction phase of the project. Yours very truly, Geo gineers, Inc McFadden, P.1 'Project Manager Jack Imo. Tuttle, P.E. Principal JJ,v1:J-K'T:cdl:pb P:\01\FIN ALS\6063 0010 1 R.DOC cc: Attention: Royce Berg (four copies) LPN Architecture & Planning, Inc. 1535 Fourth Avenue South, Suite D Seattle, Washington 98134 GeoEngineers.Inc. Plaza 600 Building 600 Stewart St..Suite 126 Seattle.VA 98101 Telephone(206)728-2674 Fax(206)728-2732 mw .geoengineers.corn Printed on recycled Caper � r TABLE OF CONTENTS INTRODUCTION ....................................................................................................... 1 SCOPEOF SERVICES................................................................................................ 1 'SITE DESCRIPTION ................................................................................................... SURFACE CONDITIONS 2 SUBSURFACE CONDITIONS 2 Site Explorations 2 Soil Conditions 3 Ground Water Conditions 3 CONCLUSIONS AND RECOMMENDATIONS ................................................................. GENERAL 3 SITE PREPARATION AND EARTHWORK 4 Site Preparation 4 Structural Fill 5 New Fill Settlements 6 Permanent Slopes 6 PRELOAD PROGRAM 7 General 7 Preload Configuration 7 Preload Fill Material 7 Preload Fill Placement 7 Settlement Monitoring 8 FOUNDATION SUPPORT 8 General 8 Shallow Foundation Support 9 Pile Foundation Support 9 Axial Pile Capacities 9 Pile Downdrag 10 Lateral Capacity 10 Settlement 10 Installation 10 FLOOR SLAB SUPPORT 11 BELOW GRADE WALLS AND RETAINING WALLS 11 PAVEMENT DESIGN 12 DRAINAGE CONSIDERATIONS 13 SEISMICITY 14 General 14 Uniform Building Code (UBC) Site Coefficient 14 Design Earthquake Levels 14 Liquefaction Potential 15 Ground Subsidence 15 LIMITATIONS......................................................................................................... 15 G e o E n g i n e e r s i File No. 6063-001-01/063098 r FIGURES Figure No. Vicinity Map 1 Site Plan 2 Settlement Plate Detail 3 APPENDICES Page No. Appendix A — Field Explorations and laboratory Testing A-1 Field Explorations A-1 Laboratory Testing A-1 APPENDIX FIGURES Figure No. Soil Classification System A-1 Key to Boring Log Symbols A-2 Log of Boring A-3...A-5 Log of Test Pit A-6...A-16 Consolidation Test Results A-17 G e o E n g i n e e r s ii File No. 6063-001-01/063098 1 T REPORT GEOTECHNICAL ENGINEERING SERVICES PROPOSED BLACKRIVER CORPORATE PARK RENTON, WASHINGTON FOR BLACKRIVER RIVERTECH L.L.C. INTRODUCTION This report presents the results of our geotechnical engineering services for the proposed Blackriver Corporate Park to be located north of the intersection of Southwest 7th Street and Oaksdale Avenue South in Renton, Washington. We understand that the project includes constructing three single-story office buildings each measuring about 25,000 to 30,000 square feet in plan and two two-story office buildings each measuring about 16,000 square feet in plan. The proposed structures will be concrete tilt-up construction. The ground level floors will be at about Elevation 19. We also understand that column loads are expected to be about 55 kips for the single story buildings and 178 kips for the two-story buildings. Based on our past experience, exterior wall loads are expected to be between 2,000 and 3,000 pounds per lineal foot. At grade parking and a wet pond are also proposed as part of the project. We understand that the City of Renton will adopted the 1997 Uniform Building Code (UBC). The 1997 UBC states that the potential for seismically induced soil liquefaction and soil instability shall be evaluated. Additionally, the 1997 UBC states that the geotechnical report shall assess potential consequences of any liquefaction and soil strength loss. Liquefaction is the loss of bearing capacity of a soil mass, which occurs when a loose saturated deposit of sand is subjected to loads of very short duration, such as occur during earthquakes. In order to evaluate the potential for liquefaction, we recommended that deep power borings be completed at the site. This was done. SCOPE OF SERVICES The purpose of our geotechnical engineering services is to evaluate the subsurface soil and ground water conditions as a basis for providing design recommendations for those elements of the proposed office park project directly affected by subsurface conditions. Our specific scope of services includes the following tasks: 1. Explore subsurface conditions at the site by excavating 11 test pits with a rubber-tired backhoe to depths ranging from about 4.5 to 15 feet. Additionally, we completed three exploratory borings to depths of about 41.5 to 44 feet each using track-mounted drilling equipment. 2. Evaluate the physical and engineering characteristics of the soils based on laboratory tests performed on samples obtained from the explorations. The laboratory tests consist of gradation, moisture content and density determinations, and consolidation tests. G e o E n g i n e e r s 1 File No. 6063-001-01/063098 Y 3. Provide earthwork criteria and site preparation recommendations for the site. This includes evaluating the suitability of on-site soils for use as structural till, constraints for wet weather construction, specifications for imported till if required, and placement and compaction requirements for structural fill. 4. Provide foundation design recommendations including allowable soil bearing pressures and settlement estimates for shallow foundations. This includes recommendations for overexcavation of unsuitable soils and preloading or surcharging to reduce the magnitude of post-construction settlements. 5. Provide recommendations for deep foundations including type of foundation, allowable capacity and penetration criteria. 6. Provide recommendations for support of on-grade floor slabs. 7. Provide recommendations for surface and subsurface drainage based on ground water conditions encountered in the explorations or expected in the area. 8. Provide recommendations for pavement design in parking and driveway areas based on typical traffic loads for this type of development. 9. Provide recommendations for mitigation of seismic impacts including the effects of potential liquefaction of the site soils. 10. Provide recommendations for permanent cut slopes made to form the wet pond. 11. Prepare a written report presenting our conclusions and recommendations together with supporting field and laboratory information for incorporation into design of the project. SITE DESCRIPTION SURFACE CONDITIONS The proposed project site is located one-half mile east of the Green River and on the Black River/Green River floodplain. The approximately 12.5-acre site is irregular in shape and presently undeveloped. Oaksdale Avenue Southwest borders the site on the south, Southwest 7th Street on the southeast, and Naches Avenue Southwest on the east. Undeveloped property borders the site to the north and the P-1 Channel extends along the west property margin. The ground surface at the project site is nearly level with approximately 2 to 3 feet variation in surface elevation. The locations of these features are shown on the Site Plan, Figure 2. SUBSURFACE CONDITIONS Site Explorations We explored subsurface soil and groundwater conditions at the site by excavating 11 test pits to depths of about 4.5 to 15.0 feet below the existing ground surface. Custom Backhoe and Dumptruck Service, Inc. using a Case 580K rubber-tired backhoe excavated the test pits on December 17, 1997. We also drilled three borings to depths of 41.5 to 44.0 below the ground surface. The borings were drilled on December 29 and 30, 1997 by Holt Drilling using track- mounted hollow-stem auger drilling equipment. The locations of the explorations are shown in G e o E n g i nee r s 2 File No. 6063-001-01/063098 r s Figure 2. The details of our field exploration program, laboratory testing and exploration logs are presented in Appendix A. Soil Conditions In general, the subsurface soil conditions are relatively uniform across the site. The explorations generally encountered an upper layer of compressible silty sand and silt to depths of about 5 to 10 feet below the ground surface. Loose sand and silty sand is present below the upper compressible layer and extends to depths of about 15 feet or more below the ground surface. Medium dense to dense sand was encountered from a depth of about 15 feet to the bottom of the borings. Sand heave occurred at some of the sampling intervals (noted on boring logs) and may have caused high blow counts. We have therefore considered this in our analyses. The loose to medium dense sands that were encountered to depths of about 15 to 25 feet or more in our borings are potentially liquefiable during strong ground shaking from large seismic events. Our foundation 'support recommendations presented below include pile foundation design criteria for the two-story structures and fill pads to support footings for the single-story structures. These measures will reduce the risk of significant damage if liquefaction occurs during strong ground shaking. Ground Water Conditions Ground water was encountered at depths of 10 to 12 feet in the borings and many of the test pits. Shallow ground water seepage was observed at depths of about 4 to 5 feet in test pits TP-8 and TP-9. No ground water seepage was observed in test pits TP-2, TP-6, TP-7, and TP-10. It is likely that perched groundwater will be present at more shallow depth across the site during the wet winter months and early summer. Ground water levels at the site should be expected to fluctuate as a function of precipitation, seasonal and other factors. The groundwater levels in the west portion of the site should be expected to fluctuate with the rise and fall of the P-1 Channel water levels. CONCLUSIONS AND RECOMMENDATIONS GENERAL Based on our experience on and review of previously completed geotechnical studies in the immediate vicinity and the results of these explorations, laboratory testing and engineering analyses, we conclude that the site can be satisfactorily developed as proposed. Compressible, silt which varies from about 5 to 10 feet or more in thickness, is present across much of the site. The silts will compress significantly under fill, foundation and floor slabs in the building areas and to a lesser degree below paved roadway and parking areas. We recommend that the building areas be preloaded to induce a significant portion of the settlement. In addition, we recommend that consideration be given to preloading the roadway G e o E n g i n e e r s 3 File No. 606 3-00 1-01/063 09 8 r r and parking areas to reduce the risk of disturbance to pavements and utilities. Loose sand was encountered in our borings to depths of 15 to 25 feet below the ground surface. The loose sand is susceptible to liquefaction during ground shaking caused by strong earthquakes. We estimate that 2 to 4 inches of total subsidence and 1 to 2 inches of differential settlement could result between adjacent columns during a magnitude 7.5 earthquake that generates ground accelerations on the order of 0.2 to 0.3 g, where g is the gravitational constant. Our recommendations include measures to reduce the potential adverse impacts of post- construction differential settlement caused by either the consolidation of the silt or liquefaction of the loose sand. The proposed single-story buildings can be supported on shallow spread footings, provided the building area is preloaded to induce a large portion of the potential settlement. Mitigation measures including a structural till pad below all footings should be included for the single- story buildings to reduce the risk of damage from liquefaction. The two-story buildings should be supported on auger-cast piles because of the long-term settlement characteristics of the underlying silt. The pile tips should extend to. at Elevation of -25 feet (pile lengths will therefore be on the order of 40 feet or more. The surface soils include silt and silty sand that are very moisture sensitive and will be difficult to operate heavy equipment on in all but the driest weather. It will also be difficult to achieve adequate compaction with these soils to allow their use as structural fill. Therefore, we recommend that you plan to use clean imported granular borrow material for all building pad, roadway and parking area fill. It may be necessary to import all fill for use in utility trench backfill within these areas as well. The following sections of this report present our conclusions and recommendations for site development, foundation support and performance estimates of the proposed structures. SITE PREPARATION AND EARTHWORK Site Preparation We understand that the project schedule provides for site work to begin during the drier summer months. Our recommendations, therefore, focus on dry weather construction, but include provisions for site work during wet weather, should construction be delayed. We recommend that pavement and building areas be stripped of all vegetation, sod and root systems. Based on our explorations, the depth of stripping required will generally be on the order of 3 to 6 inches. It may be difficult for operation of heavy equipment on the site because of the soft silt that will be exposed at the surface after stripping. We recommend that wide track dozers be used to complete much of the site stripping to avoid disturbance of the underlying soil. The underlying silt and silty sand contains a high percentage of fines and is very moisture-sensitive. If the stripping operations cause disturbance of the underlying soil, additional excavation may be necessary. Disturbance of the shallow subgrade soils should be 11 expected if site preparation work is done during periods of wet weather or when the subgrade G e o E n g i n e e r s 4 File No. 6063-001-01/063098 T 1 soils are still wet from seasonal rainfall. Material from the stripping operations should be sent off site for disposal or used for landscaping purposes. The site should be graded to a slightly crowned surface once stripping has been completed. This grading should be done to enhance drainage from the site and proposed building areas, and to prevent ponding of water in areas to receive any additional fill The exposed subgrades in building, roadway and parking areas should be evaluated as the site grading is completed in each area. Proofrolling with heavy rubber-tired construction equipment should be used for this purpose. The site should be proofrolled only after an extended period (at least two weeks) of dry weather. Probing should be used to evaluate the subgrade during periods of wet weather or when the subgrade soils are more than two or three percent wetter than their optimum moisture content. Any soft areas noted during proofrolling or probing should be excavated and replaced with compacted structural fill. We recommend that exposed subgrades in walkway areas be evaluated by probing, or by proofrolling if practical. Once the subgrade in an area has been prepared all traffic except that required to place subsequent layers of material, should be kept off the area until paving is completed. We recommend that temporary roads and laydown areas be constructed to reduce the risk of disturbing the subgrade soils. Temporary roads should consist of 12 to 18 inches of quarry spalls or clean granular structural fill placed over geotextile fabric. The geotextile should be a woven fabric intended for soil separation and reinforcement within roadway embankments. The recommended pavement sections presented in a subsequent section of this report for parking and light duty traffic (automobiles only) is not intended to support heavy construction traffic. If all or any part of these pavement sections is placed while building construction is still in progress, these areas should be barricaded and roped off to prevent vehicle access. This is to reduce the risk of softening of the subgrade, contamination of the subbase and base course materials soils, or pavement failure. The use of an asphalt treated base (ATB) pavement section for temporary roadways is discussed below under "Pavement Design." Effective erosion and sedimentation controls must be implemented during construction so that potential impacts to the adjacent wetlands and properties are reduced. The erosion and sedimentation control measures used for this project should be in accordance with the requirements of the city of Renton. Structural Fill All new tills in building and pavement areas should be placed and compacted as structural fill. The suitability of soil for use as structural fill will depend on its gradation and moisture content. In our opinion, the near surface silty soils can be considered for use as structural fill where compaction to 90 percent of maximum dry density (determined in accordance with ASTM D-1557) is sufficient and warm, dry weather prevails before and during the placement and compaction of these soils. On-site soils may not be suitable for areas where compaction to G e o E n g i n e e r s 5 File No. 6063-001-01/063098 r Y at least 95 percent is required. We recommend, therefore, that the project be planned to include importing sand and gravel for all areas where at least 95 percent compaction is required. We recommend that all imported sand and gravel contain less than 5 percent fines (material passing U.S. Standard No. 200 sieve) by weight relative to the fraction of the material passing the 3/4-inch sieve. This material should be free of debris, organic contaminants and rock fragments larger than 6 inches. All structural fill should be mechanically compacted to a firm, nonyielding condition. Structural fill placed in building areas should be compacted to a firm surface capable of supporting the structural floor slab during construction. Structural till placed in building areas may have to be compacted to a higher standard if lateral resistance on subgrade elements is required. This is discussed below under "Lateral Capacity." Pavement area fill, including utility trench backfill, should be compacted to at least 90 percent, except for the upper 2 feet below finished subgrade surface, which should be compacted to at least 95 percent. Structural fill to support walkways should be placed after the subgrade is evaluated as recommended above and be compacted to at least 90 percent. Structural fill should be placed in loose lifts not exceeding 8 to 10 inches in thickness. Each lift should be conditioned to the proper moisture content and compacted to the specified density before placing subsequent lifts. We recommend that a representative from our firm be present during proofrolling and/or probing of the exposed subgrade soils in pavement areas and placement of structural fill. Our representative will evaluate the adequacy of the subgrade soils and identify areas needing further work, perform in-place moisture-density tests in the fill to determine if the compaction specifica-tions are being met, and advise on any modifica-tions to procedure which might be appropriate for the prevailing conditions. New Fill Settlements We estimate that settlements due to new till loads will occur. We understand that 2 to 3 feet of fill will be placed to provide a generally uniform site elevation. The major portion of the settlement is expected to occur in a period of four to six weeks following placement of the fill. We estimate that 1 to 2 inches of settlement will occur due to new fill loads placed to achieve design grades. This should be considered when designing and installing utilities to reduce the risk of damage from post-construction settlement Permanent Slopes We recommend that any permanent slopes be constructed at 2HAV (horizontal to vertical), or flatter. Flatter slopes might be considered for ease of maintenance. Unprotected slopes will be subject to erosion until a protective vegetative cover is well established. Therefore, we recommend that any slope surfaces be planted as soon as practical to minimize the potential for erosion. A temporary covering, such as jute mesh, should be installed on the slopes as necessary until the vegetative cover has taken effect. G e o E n g i n e e r s 6 File No. 6063-001-01/063098 r Appropriate drainage measures, as described below in the "Drainage Considerations" section of this report, should be implemented to collect and control surface runoff and ground water seepage. PRELOAD PROGRAM General We recommend that a preload fill be placed over the building area to induce a major portion of the settlement that would otherwise occur when the area building loads are applied. A preload program involves placing additional fill on the structural fill pad for the building to induce a major portion of the settlement in advance of building construction. The preload program will also reduce potential differential settlement due to variability in the thickness and compressibility of the underlying soils. The required thickness of preload fill and the area to be covered are evaluated on the basis of soil properties, planned floor loads, the time available for preloading and the magnitude of postconstruction settlement the structure can tolerate. We evaluated a preload program based on a design floor loads of 200 pounds per square foot (psf) and a finished lower floor grade of Elevation 19 feet. If the design loads and grades vary from those assumed we should be given the opportunity to review the preload recommendations and provide any necessary modifications. Preload Configuration We recommend using a preload height of at least 2.5 feet for all building areas. The thickness of preload fill is to be measured from the design finished floor elevation. Thus, for a design floor grade of Elevation 19 feet, the preload should be placed to Elevation 21.5 feet. The preload thickness includes an allowance for settlement such that the top of the preload at the completion of the program will be at approximately Elevation 19. The crest of the preload fill should extend to full height for a horizontal distance of at least 5 feet beyond the perimeter of the proposed building areas. The preload surface should be crowned slightly to promote drainage of surface water. Preload Fill Material We recommend that material imported for preload fill consist of structural fill quality material, as described above in the "Earthwork" section of this report, so that it can be used in filling and grading other portions of the site. Use of structural fill quality material will also minimize difficulties in rehandling and compaction if the fill must be removed during inclement weather. Preload Fill Placement We recommend that the preload fill up to finish floor elevation be placed and compacted as structural fill, as recommended above in the "Earthwork" section of this report. The remaining preload fill need be compacted only to the extent necessary to support construction equipment. G e o E n g i n e e r s 7 File No. 6063-001-011063098 t 4 Following the preloading period, the excess material can be removed from the building area and used as structural fill in other areas such as parking or roadway areas or in other building pads if the structures are to be built sequentially. Once the preload fill is removed, we recommend that the upper 12 inches of the building pad fill be evaluated and recompacted as necessary to meet the compaction criteria specified above before the floor slab or footings are constructed. Settlement Monitoring To evaluate the magnitude and time rate of settlement of the building pad preload fill, we recommend that settlement-monitoring plates be installed prior to placing any fill in the building areas. We estimate that the preload fill will need to be left at full height a minimum of two to three weeks. If settlement-monitoring data indicates that settlement is occurring at a rate greater than that estimated, the duration of preloading may be reduced appropriately. We recommend that settlement plates be placed approximately 25 feet in from each corner of the building. An example of a suitable settlement plate and a description of monitoring procedures are presented in Figure 3. Initial elevation readings of the settlement plates must be obtained when they are installed and before any fill is placed. If this is not clone, the initial settlement behavior of the fill pad will not be recorded and the value of the observations diminished in that the total magnitude of settlement will be unknown. This may result in a longer preload period than would otherwise be necessary. The elevations of the plates and the adjacent ground surface should be determined to within ±0.005 feet every other day during filling and once a week after completion of filling. We recommend that the readings be taken by the project civil engineer and the results forwarded to our office promptly after each reading for evaluation. The presence of the measurement rods that extend from the settlement plates through the fill will inhibit the mobility of earthmoving equipment to some extent. The contractor will have to exercise care to avoid damaging the rods. The construction documents should emphasize the importance of protecting the settlement plates and measuring rods from disturbance. FOUNDATION SUPPORT General Based on our analyses, we recommend that that single-story buildings be supported on shallow foundations bearing on at least a 4-foot thickness of crushed rock fill to provided uniform support and reduce the risk of differential settlement from ground subsidence during a strong earthquake. We recommend that the two-story buildings be supported on pile foundations to reduce the risk of damage from consolidation of the underlying compressible silt and ground subsidence during strong ground shaking. Recommendations for shallow foundations for support of retaining walls and ancillary structure, and pile foundations are presented below. G e o E n g i n e e r s 8 File No. 6 063-00 1-01106309 8 l t Shallow Foundation Support We recommend that all shallow foundations be supported on zone crushed rock or controlled density fill (CDF) to provide uniform foundation support and reduce the risk of differential settlement during strong ground shaking. The zone of crushed rock or CDF should extend to a depth of at least one-half the footing width or 4 feet whichever is greater, below bottom of footing grade. The zone of crushed rock or CDF should extend laterally beyond the edges of the footings a minimum distance equal to the thickness of the zone of fill placed. The silty soils encountered at shallow depth are easily disturbed. The excavations for the supporting layer of crushed rock or CDF should be made with a smooth edged bucket to minimized disturbance of the native soils. If the exposed soils are wet and softened by the excavation, a layer of geotextile should be placed before filling the excavation with crushed rock. If CDF is used, a geotextile should not be needed. If crushed rock fill is used, we recommend that the initial lift be at least 18 inches thick and be compacted sufficiently to form a firm base for the remainder of the fill. Compaction should be limited so that pumping or weaving does not develop in the silty soils. The remainder of the crushed rock fill should be compacted to at least 95 percent of the maximum dry density. The crushed rock or CDF should be placed as soon as each excavation is completed. The exposed bearing surface should be recompacted as necessary before footings are constructed. We recommend that exterior footings be founded at least 18 inches below lowest adjacent finished grade. Interior footings should be founded a minimum of 12 inches below bottom of slab. The recommended allowable bearing pressure for footings supported as recommended is 2,500 psf. The allowable soil bearing pressure applies to the total of dead plus long-term live loads and may be increased by up to one-third for short-term live loads such as wind or seismic forces. We recommend that all excavations for footing construction be observed by a representative from our firm to determine if the work is being completed in accordance with our recommendations and that subsurface conditions are as expected. Pile Foundation Support Axial Pile Capacities. We recommend that 18-inch-diameter augercast piles be used to support the building loads. The augercast piles should extend a minimum distance of 15 feet into the underlying dense sand which was encountered at a depth of about 25 to 30 feet below the ground surface. We recommend that the piles extend at least 45 feet below the existing ground surface, which corresponds to a tip about Elevation —25 feet. Based on our review and analyses, we recommend that the piles be designed for a maximum allowable structural downward capacity of 80 tons. This recommendation includes consideration of potential downdrag forces and a factor of safety of about 2 for skin friction and 3 for end bearing. An uplift capacity of 30 tons may be used for the piles (factor of safety of about 2). These capacity G e o E n g i n e e r s 9 File No. 6 063-00 1-01/063 09 8 values may be increased by one-third when considering design loads of short duration such as wind or seismic forces. The allowable capacities presented above are based on the strength of the supporting soils for the penetrations indicated and ignore the weight of the pile. The capacities apply to single piles. If piles within groups are spaced at least 3-pile diameters on center, no reduction for pile group action is required. The characteristics of pile materials and structural connections might impose limitations on pile capacities and should be evaluated by your structural engineer. Full length steel reinforcing will be needed to develop the uplift capacity. Pile Downdrag. Pile downdrag forces develop when surrounding soils settle relative to a pile, thus interacting with and adding load to the pile. At this site, downdrag forces can be expected to develop on the piles during seismic ground shaking if liquefaction of the underlying soil occurs. The recommendations presented above for allowable axial capacity in compression include the effects of downdrag on the piles; therefore, total pile loads will consist of an allowable design load of 80 tons and 15 tons of downdrag for a total of 90 tons. Lateral Capacity. Allowable lateral loads on closely spaced piles or other subgrade elements are, in part, a function of the spacing between these elements. We recommend a minimum pile spacing of 3-pile diameters center-to-center, both parallel and normal to the principal direction of load application. Allowable lateral capacities for various pile spacings, expressed in terms of D (pile diameter) parallel to the direction of load application are tabulated below. Lateral Pile Capacity Pile Spacing Allowable Lateral Pile Capacity (Parallel to direction of loading) (kips) 3D 6 4D 6 6D 11 8D 15 The above lateral capacities are based on pile-head fixity against rotation and a maximum pile deflection of approximately 1/2-inch and include a factor of safety of about 2. We recommend that reinforcing sufficient to resist the expected bending moments be installed to a minimum depth of 20 feet in the 18-inch-diameter augereast piles. Resistance to lateral loads can also be developed by passive pressures on the face of pile caps and other foundation elements. Passive pressures may be computed using an equivalent fluid density of 225 pounds per cubic foot (pct), provided all fill adjacent to the face of the pile cap or other foundation element is compacted to at least 95 percent of the maximum dry density for a distance at least equal to 2.5 times the depth of the element. The above equivalent fluid density value includes a factor of safety of about 1.5. G e o E n g i n e e r s 10 File No. 6063-001-01/063098 Settlement. We estimate that the total settlement of augercast piles designed and installed as recommended will be about 1/2 to 1 inch for downward loads of 80 tons. Most of this settlement is expected to occur rapidly during construction as loads are applied. Postconstruction differential settlements should be less than '/2 inch, depending upon the distribution of building loads. Installation. We recommend that augercast piles be installed by an experienced contractor to the recommended penetration using a continuous-flight, hollow-stem auger. Pumping grout under pressure through the hollow stem as the auger is withdrawn forms the pile. Reinforcing steel for bending and uplift loads is placed in the fresh grout column immediately after withdrawal of the auger. We recommend that a waiting period of at least 24 hours be maintained between installation of piles spaced closer than 10 feet center-to-center in order to avoid disturbance of fresh grout in a previously cast pile. We recommend that minimum 3,500 pounds per square inch (psi) grout strength be used for augercast piles. Grout pumps must be fitted with a volume-measuring device and pressure gauge so that the volume of grout placed in each pile and the pressure head maintained during pumping can be determined. A minimum grout line pressure of 100 psi should be maintained. The rate of auger withdrawal should be controlled during grouting such that the volume of grout pumped is equal to at least 115 percent of the theoretical hole volume. A minimum head of 10 feet of grout should be maintained above the auger tip during withdrawal of the auger to maintain a full column of grout and prevent hole collapse. We recommend that pile installation be monitored by a member of our staff who will observe the drilling operations, record indicated penetrations into the supporting soils, monitor grout injection procedures, record the volume of grout placed in each pile relative to the calculated volume of the hole, and evaluate the adequacy of individual pile penetrations. FLOOR SLAB SUPPORT We recommend that floor slabs be supported on grade after completion of the preload program described above. We further recommend that the slab be constructed on a base course consisting of at least 6 inches of well-graded sand and gravel or crushed rock containing less than 3 percent fines. The base course should be compacted to at least 90 percent of maximum dry density. The base course will provide uniform support and serve as a capillary break to reduce moisture migration through the slab. A vapor retarder consisting of plastic sheeting placed over the capillary break can be installed if additional protection against migration of moisture into the slab is needed. A 2-inch-thick layer of sand should be placed over the vapor retarder to protect it during slab construction and to aid in uniform curing of the concrete. BELOW GRADE WALLS We understand that below-grade walls are expected for elevator pits. These below-grade walls, which are typically constrained from rotating outward, should be designed for a lateral G e o E n g i n e e r s 11 File No. 6063-001-01/063098 pressure based on an equivalent fluid density of 55 pcf. Heavy compaction equipment should not be operated adjacent to the walls within a distance equal to the height of the walls. The till within this zone should be compacted with relatively light, hand-operated mechanical equipment. Passive resistance acting on portions of the walls should be evaluated using an equivalent fluid density of 225 pcf where footing faces located below existing grade are surrounded by structural fill compacted to at least 95 percent of maximum dry density as recommended. We recommend that continuous wall footings be at least 18 inches wide and that they be founded at least 18 inches below lowest adjacent finished grade. We also recommend an allowable bearing value of 2,500 psf for footings supported as described in the Shallow Foundation Support section. Frictional resistance on the base of the footings can be evaluated using 0.4 for the coefficient of base friction. The above values incorporate a factor of safety of about 1.5. Positive drainage should be provided behind below-grade walls by placing a zone of free draining sand and gravel containing less than 3 percent fines against the wall. This drainage zone should be at least 12 inches wide (measured horizontally) and extend along the entire height of the wall. Perforated pipe must be installed at the base of this drainage layer and be connected to tightlines that direct the flow to the storm drain or other suitable disposal point. PAVEMENT DESIGN The exposed subgrade in pavement areas should be proofrolled or otherwise examined as discussed above in the "Site Preparation' section of this report to detect areas of soft subgrade or unsuitable soils. Soft or disturbed areas which develop in the subgrade should be removed and replaced with granular fill compacted as recommended to provide adequate pavement support. The thickness of additional sand and gravel fill required will depend upon the firmness of the subgrade at specific locations and should be evaluated during construc-tion. In soft subgrade areas, we recommend that considera-tion be given to placing a woven geotextile between the existing fill soils and the structural fill as a separation layer. We recommend that the pavement section in automobile parking areas consist of minimum thicknesses of 2 inches of Class B asphalt concrete, 4 inches of clean crushed rock base, and 9 inches of subbase, provided the subgrade is prepared as recommended and that pavement construction is done during a period of extended dry weather. In roadway and trick loading areas, the minimum thickness should be 3 inches of asphalt concrete, 6 inches of crushed rock base and 12 inches subbase. The subbase material should meet the requirements previously specified for gradation of structural fill. The crushed rock base course and subbase should each be compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM D-1557. It is important to pavement performance that backfill in utility trenches located in areas to be paved also be compacted as specified for structural fill. G e o E n g i n e e r s 12 File No. 6063-001-011063098 The above pavement section recommendations are based on having a relatively dry and stable subgrade on which to place the subbase, base course and paving. Some differential settlement of pavement areas should be expected due to weight of the pavement section placed over the underlying soft soils. We recommend that final paving in areas receiving 1 or more feet of fill be delayed as long as possible once the subgrade has been prepared and the structural fill subbase has been placed to allow some settlement to occur. It may be desirable to place ATB (asphalt treated base) in place of the base course layers if permanent roadway alignments will be used for access during construction. This will be particularly important if building construction continues into the winter season and roadway and parking areas have not yet been paved. The ATB will, in conjunction with the subbase, provide a section less susceptible to damage than the base course and subbase layers only. The required thickness of subbase material can be reduced with an ATB section. We recommend that this alternative pavement section in automobile parking areas consist of minimum thickness of 2 inches of Class B asphalt concrete, 4 inches of ATB and 6 inches of subbase. In roadway and truck loading areas, the minimum thicknesses should be 3 inches of asphalt concrete, 7 inches of ATB and 6 inches of subbase. It is important to realize that some damage will likely occur to the ATB and subgrade during construction and repair may be necessary prior to final paving. Areas accessible to heavy construction traffic should be limited to prevent excessive damage to the ATB and subgrade. We recommend that the ATB be evaluated by proofrolling prior to placing final pavement. Soft areas observed during proof rolling should be removed and the subgrade repaired as recommended above under "Site Preparation." It is important for proper pavement performance to keep the subbase drained. We recommend that the subgrade be sloped to drain toward the on-site catch basins and drainage swales. Drainage can then be accomplished by providing a positive hydraulic connection between the subbase and the swales and providing weep holes in the sides of the catch basins. The weep holes should be protected with a drainage geotextile on the outside of the catch basin to prevent loss of subbase material. We recommend that the weep holes be 1/2 inch in diameter and spaced at about 6 inches on center around all sides of the catch basin at the subgrade elevation. DRAINAGE CONSIDERATIONS We expect that shallow perched groundwater may be encountered during grading, foundation, elevator shaft and utility excavation. We anticipate that this water can be tempor- arily handled during construction by ditching and pumping from sumps, as necessary. All collected water should be safely routed to suitable discharge points. We recommend that perimeter footing drains be installed for all buildings. The perimeter drains should be installed at the base of the exterior footings. The perimeter drains should be provided with cleanouts and should consist of at least 4-inch-diameter perforated, smooth- G e o E n g i n e e r s 13 File No. 6063-001-01/063098 T walled PVC pipe placed on a bed of, and surrounded by 6 inches of drainage material enclosed in a non-woven geotextile to prevent fine soil from migrating into the drain material. The drainage zone should consist of free-draining gravel containing less than 3 percent fines. The perimeter drains should be sloped to drain by gravity, if practicable, to a suitable discharge point, preferably a storm drain. Roof runoff should be collected in a tightline system and routed to suitable discharge points. All paved and landscaped areas should be graded so that surface drainage is directed away from the buildings to appropriate catch basins. SEISMICITY General The Puget Sound area is a seismically active region and has experienced thousands of earthquakes in historical time. Seismicity in this region is attributed primarily to the interaction between the Pacific, Juan de Fuca and North American plates. The Juan de Fuca plate is subducting beneath the North American Plate. Each year 1,000 to 2,000 earthquakes occur in Oregon and Washington. However, only 5 to 20 of these are typically felt because the majority of recorded earthquakes are smaller than Richter magnitude 3. In recent years two large earthquakes occurred which resulted in some liquefaction in loose alluvial deposits and significant damage to some structures. The first earthquake, which was centered in the Olympia area, occurred in 1949 with a Richter magnitude of 7.1. The second earthquake, which occurred in 1965, was centered between Seattle and Tacoma and had a Richter magnitude of 6.5. Uniform Building Code (UBC) Site Coefficient The Puget Sound region is designated as a Seismic Zone 3 in the 1997 edition of the Uniform Building Code (UBC). For Zone 3 locations, a Seismic Zone Factor (Z) of 0.30 is applicable based on UBC Table 16-I. In our opinion, the soil profile at the site is best characterized as Type Sp, based on UBC Table 16-J. Design Earthquake Levels The key seismic design parameters are the peak acceleration and the Richter magnitude of the earthquake. In general, a design earthquake is chosen based on a probability of exceedence (the probability that the design earthquake will not be exceeded over a given time period). The level of seismicity recommended in the 1994 edition of the UBC for human occupancy buildings is an earthquake with a 10 percent probability of exceedence in a 50-year period. The design earthquake event that corresponds to this probability of exceedence is an earthquake with a Richter magnitude of 7.5 and a peak horizontal ground acceleration of approximately 0.3g. G e o E n g i n e e r s 14 File No. 6063-001-01/063098 Liquefaction Potential Liquefaction is a condition where soils experience a rapid loss of internal strength as a consequence of strong ground shaking. Ground settlement, lateral spreading and/or sand boils may result from soil liquefaction. Structures supported on liquefied soils can suffer foundation settlement or lateral movement that may be severely damaging to the structures. Conditions favorable to liquefaction occur in loose to medium dense, clean to moderately silty sand that is below the ground water table. This condition is present at this site. Therefore, we performed an engineering evaluation of the liquefaction potential of the site soils. The evaluation of liquefaction potential is dependent on numerous parameters including soil type and grain size distribution, soil density, depth to ground water, in-situ static ground stresses, and the earthquake induced ground stresses. Typically, the liquefaction potential of a site is evaluated by comparing the cyclic shear stress ratio induced by an earthquake with the cyclic shear stress ratio required to cause liquefaction. The cyclic shear stress ratio required to cause liquefaction was estimated using an empirical procedure based on the in-situ static ground stresses, the blow count data obtained during. sampling in the borings, and the design earthquake magnitude. To evaluate potential liquefaction at this site, we evaluated the earthquake induced cyclic shear stress ratio using the design earthquake event presented above. The results of our analyses indicate that the loose to medium dense sand below the ground water level has a moderate to high potential for liquefaction during an earthquake with a Richter magnitude of 7.5 or greater. Ground Subsidence Because of the presence of potentially liquefiable soils at the site, ground subsidence may be expected if liquefaction occurs. The magnitude of subsidence resulting from liquefaction will vary depending on the actual levels of ground shaking, the duration of shaking, and site- specific soil conditions. We estimate that total liquefaction induced ground subsidence may be on the order of 2 to 4 inches or more. We estimate that differential movements may be on the order of one-half of the total amount of subsidence. LIMITATIONS We have prepared this report for use by Blackriver Rivertech L.L.C., LPN Architecture and Planning, Inc. and other members of the design team for use in the design of a portion of this project. The conclusions and recommendations in this report should be applied in their entirety. The data and report should be provided to prospective contractors for bidding or estimating purposes; but our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. If there are any changes in the grades, location, configuration or type of construction planned, the conclusions and recommendations presented in this report might not be fully G e o E n g i n e e r s 15 File No. 6063-001-01/063098 e applicable. If such changes are made, we should be engaged to review our conclusions and recommendations and to provide written modification or verification, as appropriate. When the design is finalized, we recommend that we be engaged to review those portions of the specifications and drawings that relate to geotechnical considerations to see that our recommendations have been interpreted and implemented as intended. There are possible variations in subsurface conditions between the locations of explorations. Variations may also occur with time. Some contingency for unanticipated conditions should be included in the project budget and schedule. We strongly recommend that sufficient monitoring, testing and consultation be provided by our firm during construction to (1) determine if the conditions encountered are consistent with those indicated by the explorations, (2) provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and (3) evaluate whether or not earthwork and foundation installation activities comply with the contract plans and specifications. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in this area at the time the report was prepared. No warranty or other conditions, express or implied, should be understood. We trust this provides the information you require at this time. We appreciate the opportunity to be of service to you on this project. Please contact us should you have any questions concerning our findings or recommendations, or should you require additional information. Respectfully submitted, S I�tcF,q� GeoEngineers, Ins . � I y b ?BoFadden, P.E. 126693 �� ;,`, Xroject Manager CISTY, G1� SIGNAL F;r Is6i , EXPIRES 3 Jack K. Tuttle, P.E. 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This mcp is copyrighted by THOMAS BROS. MAPS. It is unlawful to copy or reproduce all or any part thereof, whether for personcl use or resale, without permission. 5 ��� VICINITY MAP Geo��EnQibneers FIGURE 1 x Measurement Rod, 1/2-inch- diameter Pipe or Rebar Casing, 2-inch-diameter Pipe (set on plate, not fastened) Existing Ground Surface Coupling Welded to Plate '�li\1 r\l i, \iy4/v J/, .Ali/..I ,�,•� A .I�I0./L. /i///�.�'. 1 //llll AAA '•� ////,// (Not to Scale) Settlement Plate, Sand Pad, if Necessary 16"x 16" x 1/4" NOTES: 1. Install settlement plates on firm ground or on sand pads if needed for stability. Take initial reading on top of rod and at adjacent ground level prior to placement of any fill. 2. For ease in handling, rod and casing are usually installed in 5-foot sections. As fill progresses, couplings are used to install additional lengths. Continuity is maintained by reading the top of the measurement rod, then immediately adding the new section and reading the top of the added rod. Both readings are recorded. 3. Record the elevation of the top of the measurement rod at the recommended time intervals. Record the elevation of the adjacent fill surface every time a measurement is taken. 4. Record the elevation of the top of the measurement rod to the nearest 0.01 foot, or 0.005 foot, if possible. Record the fill elevation to the nearest 0.1 foot. co 5. The elevations should be referenced to a temporary benchmark located on stable ground at least 100 M feet from the area being filled. N O S I co SETTLEMENT PLATE DETAIL Geo VOO Engineers FIGURE 3 GAtemplate�settIe.pre i . . ...__ i ,` :: ',. \ ,ice , �`r,{ -�.�,✓ � � _ /. 7 1lit- 0-4 .\ _ ; / -, l l_ _ � \ is t \`' / � -� / •.• _, 1 ''' - ,. •�i \ 1 i l, � ` C' ' `1, �G ,� �1 J I I •J t a �. 1 ;I. ,�J\° 4 / � � ! ` . I• \ �: � � � /� �>-f' ,/ \ ` r � 1/ .' 11 4 a , APPENDIX A FIELD EXPLORATIONS AND LABORATORY TESTING FIELD EXPLORATIONS We explored subsurface soil and groundwater conditions at the site by excavating 11 test pits to depths of about 4.5 to 15.0 feet below the existing ground surface. The test pits were excavated on December 17, 1997, by Custom Backhoe and Dumptruck Service, Inc. using a Case 580K rubber-tired backhoe. We also drilled three borings to depths of 41.5 to 44.0 below the ground surface. The borings were drilled on December 29 and 30, 1997 feet by Holt Drilling using track-mounted hollow-stem auger drilling equipment. Locations of the explorations were determined in the field by pacing distances from existing site features and/or matching the contours on the site with the topographic map prepared by Bush, Roed & Hitchings, Inc. dated March 24, 1997. Ground surface elevations shown on the exploration logs are based on the same topographic map. The locations of the explorations are shown on the Site Plan, Figure 2. The explorations were continuously monitored by a geologist from our firm who visually examined and classified the soils encountered, obtained representative soil samples, observed ground water conditions, and prepared a detailed log of each exploration. Disturbed samples were obtained from the test pits. A 3-inch outside- diameter, heavy duty split-barrel sampler with brass liner rings was used to obtain relatively undisturbed samples from the borings. The blow counts resulting from driving this sampler with a 300-pound hammer falling 30 inches area roughly equivalent to those from the Standard Penetration Test. The number of blows required to drive the sampler the last 12 inches, or other indicated distance, is recorded on the boring logs. Soils encountered were visually classified in general accordance with the classification system described in Figure A-1. A key to the boring log symbols is presented in Figure A-2. The boring logs are presented in Figures A-3 through A-5. The test pit logs are presented in Figures A-6 through A-16. The logs are based on our interpretation of the field data and indicate the various types of soils encountered. They also indicate the depths at which the soils or their characteristics change, although the change might actually be gradual. The densities noted on the boring logs are based on the blow counts. The densities noted on the test pit logs are based on the difficulty of excavating, probing with a 1/2-inch-diameter hand probe, and our experience and judgment of the conditions encountered. The borings were backtilled in general accordance with local regulatory requirement. The test pits were loosely backfilled with the excavated material upon completion. LABORATORY TESTING Selected soil samples obtained from the test pits were returned to our lab and visually examined to confirm or modify field classifications. Selected soil samples were tested to determine their natural moisture content and dry density. The results of the moisture content G e o E n g i n e e r s A-1 File No. 6063-001-01/063098 y a and density determinations are presented on the boring and test pit logs. In addition a consolidation test was completed for the compressible soil encountered in the borings. The results of this test are presented in Figure A-17. G e o E n g i n e e r s A-2 File No. 6063-00 1-01/06309 8 l A SOIL CLASSIFICATION SYSTEM GROUP MAJOR DIVISIONS SYMBOL GROUP NAME GRAVEL CLEAN GW WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL COARSE GRAVEL GRAINED GP POORLY-GRADED GRAVEL SOILS More Than 50% of Coarse Fraction GRAVEL GM SILTY GRAVEL Retained WITH FINES on No. 4 Sieve GC CLAYEY GRAVEL More Than 50% Retained on SAND CLEAN SAND SW WELL-GRADED SAND, FINE TO COARSE SAND No. 200 Sieve SP POORLY-GRADED SAND More Than 50% of Coarse Fraction SAND SM SILTY SAND Passes WITH FINES No. 4 Sieve SC CLAYEY SAND FINE SILT AND CLAY ML SILT GRAINED INORGANIC SOILS CL CLAY Liquid Limit Less Than 50 ORGANIC OL ORGANIC SILT, ORGANIC CLAY More Than 50% SILT AND CLAY MH SILT OF HIGH PLASTICITY, ELASTIC SILT Passes INORGANIC CH CLAY OF HIGH PLASTICITY, FAT CLAY No. 200 Sieve Liquid Limit 50 or More ORGANIC OH ORGANIC CLAY,ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS: 1. Field classification is based on visual examination of soil Dry- Absence of moisture, dusty, dry to the touch in general accordance with ASTM D2488-90. Moist- Damp, but no visible water 2. Soil classification using laboratory tests is based on ASTNI D2487-90. Wet - Visible free water or saturated, usually soil is obtained from below water table 3. Descriptions of soil density or consistency are based on interpretation of blow count data, visual appearance of soils, and/or test data. C) 0 i u its SOIL CLASSIFICATION SYSTEM W Geo��Engineers FIGURE A-1 LABORATORY TESTS SOIL GRAPH: AL Atterberg Limits CID Compaction SM Soil Group Symbol CS Consolidation (See Note 2) DS Direct shear GS Grain size Distinct Contact Between %F Percent fines Soil Strata HA Hydrometer Analysis SK Permeability Gradual or Approximate SM Moisture Content Location of Change MD Moisture and density Between Soil Strata SP Swelling pressure TX Triaxial compression Water Level UC Unconfined compression CA Chemical analysis Bottom of Boring BLOW COUNT/SAMPLE DATA: 22 ® Location of relatively Blows required to drive a 2.4-inch I.D. undisturbed sample split-barrel sampler 12 inches or other indicated distances using a 12 ® Location of disturbed sample 300-pound hammer falling 30 inches. 17 E] Location of sampling attempt with no recovery 10 ❑ Location of sample obtained Blows required to drive a 1.5-inch I.D. in general accordance with (SPT) split-barrel sampler 12 inches Standard Penetration Test or other indicated distances using a (ASTM D-1586) procedures 140-pound hammer falling 30 inches. zs m Location of SPT sampling attempt with no recovery ® Location of grab sample "P" indicates sampler pushed with weight of hammer or against weight of drill rig. NOTES: 1. The reader must refer to the discussion in the report text, the Key to Boring Log Symbols and the exploration logs for a proper understanding of subsurface conditions. 2. Soil classification system is summarized in Figure A-1. KEY TO BORING LOG SYMBOLS Geo Engineers 0�/ b FIGURE A-2 TEST DATA BORING B-1 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 20.0 Lab Tests (%) (pcf) Count Samples Symbol 0 ML Brown silt to brown silt with sand(soft to medium still;moist) 0 MD 38 78 8 ■' 1 5 MD,CS 37 74 P 2 P �I ML Grayish brown silt(medium stiff moist) 3 10 p SM Grayish brown fine to medium silty sand(loose,moist) ML Brownish gray silt with a trace of fine sand(soft to medium stiff MD 43 75 5 wet) 4 15 SP Gray fine to coarse sand with fine to medium gravel and a trace of 5 LU w organic matter(wood)(dense,wet) w LL LLJ MD 7 124 32 a 6 = F— wp 20 w a 7 43 SP-SM Gray fine to medium sand with silt and a trace of fine gravel(dense, wet) 25 8 SP Gray fine to medium sand and a trace of silt(dense,tvet) - D MD 22 98 46 ' ....... 2-foot heave during sampling D 9 g 30 Y 10 42 ° Q GM Gray silty fine gravel with fine to coarse sand(dense,wet) 2-foot heave during sampling 35 SP-SM Gray fine to medium sand with silt to silty fine sand(loose,wet) 11 C c2 17 7 ■ " 0 12 0 0 40CD CD Note:See Figure A-2 for explanation of symbols Mal ���. LOG OF BORING Geo jkR%' Engineers FIGUREA-3 TEST DATA BORING B-1 (Continued) DESCRIPTION 'Moisture Dry Content Density Blow Group Lab Tests (°io) (pcO Count Samples Symbol 40 SP Grav fine to medium sand with a trace of silt and organic matter (wood)(dense,wet) 13 35 Boring completed at 44.0 feet on 12;30i97 45 Ground water encountered at 12.0 feet durine drilling 14 15 50 16 55 17 � - cn w W w - w w F. z_ LLJ = 18Z a _ � w 60 o w 0 - 19 65 _ 20 Q _ 0 " 21 70 Y O 22 75 23 0 r2 0 24 0 0 CD 80 CD W Note:See Figure A-2 for explanation of symbols LOG OF BORING G e o OF,Engineers FIGURE A-3 TEST DATA BORING B-2 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 20.0 Lab Tests (%) (pcf) Count Samples Symbol ML Brown silt with a trace of fine sand and organic matter(soft,very 0 moist) MD 26 84 6 ■ 1 %F=63 SM Brownish gray silty fine sand with a trace of organic matter(roots) (loose,moist) 2 10 3 MD 33 82 8 ■ ::::::: 4 - %F=23 15 .. SP Gray fine to medium sand with a trace of silt(very dense,wet) F 5 LU C W - W W F- W 23 e ::::::: 2.5 feet of heave F- — 6 T p 20 e� L'J 5.0 feet of heave-switch to drilling mud 7 22 25 s MD 26 97 16 ■ ::::::: %F=2 9 a 30 SP Gray fine to coarse sand with a trace of silt(very dense,wet) c 10 56 35 SP-SM Gray fine to medium sand with silt and shell fragments(very dense, wet) 11 n - MD 20 107 50 %F=10 12 40 0 D Note:See Figure A-2 for explanation of symbols ��� LOG OF BORING Geo��Engineers FIGURE A-4 TEST DATA BORING B-2 (Continued) DESCRIPTION Moisture Dry Content Density Blow Group Lab Tests (°'o) (pcf) Count Samples Symbol 40 13 MD 25 97 7 Bonne completed at 44.0 feet on 12/30:'97 45 Ground water encountered at 13.3 feet during drilling 14 15 50 16 55 17 H U) w 0� L w LL w z g F- 18 CL 0 60 w _ o 1s 65 20 b J) 21 70 Y 22 75 23 0 17 0 24 0 0 0 80 0 Note:See Figure A-2 for explanation of symbols �� LOG OF BORING Geo 40, ngineers FIGURE A-4 TEST DATA BORING B-3 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 18.0 Lab Tests (%) (pct) Count Samples Symbol 0 :: SM Brown silty fine to medium sand with a trace of organic matter 0 (roots)(medium dense,moist) MD 21 99 12 ■ ......: %F=49 5 5 ML Gray silt with a trace of fine sand and organic matter(roots)(soft to medium stiff,moist) MD 40 79 7 d 10 10 3 e SM Gray silty fine to medium sand(loose to medium dense,moist) 15 15 W SP W Gray fine to medium sand with a trace of silt(medium dense to LL dense, wet) = 17 ❑ a p 20 20 MD 14 100 35 0 3 feet of heave 25 25 co m 24 : 3 feet of heave E 30 30 3 O 48 SP-SM Gray fine to coarse sand with silt and fine gravel(very dense,wet) 35 35 0 38 ❑ o _ 0 38 ❑::: ro 40 40 0 0 Note:See Figure A-2 for e\planation of symbols ��� LOG OF BORING Geo��Engineers FIGURE A-5 TEST DATA BORING B-3 (Continued) DESCRIPTION Moisture Dry Co-tent Density Blow Group Lab Tests (°io) (pcf) Count Samples Symbol 40 40 56 ■ Boring completed at 41.5 feet on 12/29/97 Ground water encountered at 12.4 feet during drilling 45 45 50 50 55 55 H w w - - w z H a w 0 60 60 65 65 co Q) V N _V 70 70 75 75 0 0 0 4 80 60 0 `z Note:See Figure A-2 for explanation of symbols � LOG OF BORING Geo t$�Engineers FIGURE A-5 TEST DATA TEST PIT 1 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 20.0 Lab Tests (%) (pcf) Count Samples Symbol 0 ML Brown silt with a trace of fine sand, fine gravel and organic matter 0 (medium stiff; moist) 1 SM 38 2 ML Brown silt with a trace of fine sand(medium stiff;moist) 3 4 5 SM Gray to brown silty fine sand(loose,moist) 5 6 w w u_ 7 z_ E-• a 0 8 9 10 10 co 11 v N h E 12 SP Gray fine to medium sand with a trace of silt(loose,%vet) 13 14 0 15 Test pit completed at 15.0 feet on 12/17/97 15 oModerate ground water seepage observed at 12.0 feet oModerate ca%ing observed between 7.0 and 15.0 feet 0 A 16 0 `o Note:See Figure A-2 for explanation of symbols <A111. LOG OF TEST PIT Geo*o Engineers FIGURE A-6 T TEST DATA TEST PIT 2 DESCRIPTION Moisture Content D-nsity Blow Group Surface Elevation(ft.): 19.0 Lab Tests (%) (pcO Count Samples Symbol 0 NIL Brown silt with a trace of fine to medium sand,fine gravel and 0 organic matter(medium stiff moist) 1 2 NIL Brown silt with a trace of fine sand(medium stiff;moist) 3 SM 35 4 SM Gray silty fine sand(loose,moist) Test pit completed at 4.5 feet on 12/17/97 5 No ground water seepage observed 5 No caving observed 6 F- w w LL 7 Z 2 F-- a w 8 0 s 10 10 co 11 N E u 12 O 13 14 0 15 15 17 0 0 16 - co 0 Note.See Figure A-2 for explanation of symbols �� LOG OF TEST PIT Geo Wa Engineers FIGURE R-7 TEST DATA TEST PIT 3 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 16.0 Lab Tests (%) (pcf) Count Samples Symbol 0 j:.: SM Dark brown silty fine to medium sand with a trace of fine gravel 0 ML and organic matter(loose,moist) Gray to brown silt with a trace of sand(medium stiff; moist) 1 - 2 3 4 5 SM Gray silty fine to medium sand(loose,moist) 5 6 w w u_ 7 Z_ 2 F- w 8 SP Gray fine to medium sand with a trace of silt(loose to medium Q dense,wet) 9 10 10 SP Gray fine to coarse sand with a trace of silt and organic matter N :" (loose to medium dense,wet) N E 12 13 14 Test pit completed at 14.0 feet on 12/17/97 Rapid ground water seepage obsmed at 10.5 feet Severe ca%ing between 7.0 and 14.0 feet CD 15 15 0 0 o _ 0 16 - 0 `D Note:See Figure A-2 for explanation of symbols � LOG OF TEST PIT Geo��Engineers FIGURE A-8 TEST DATA TEST PIT 4 DESCRIPTION Moisture Content Density Blow Group Surface Elevation(ft.): 19.0 Lab Tests (%) (pcf) Count Samples Symbol 0 SP Brown fine to coarse sand with a trace of silt and fine organic 0 matter(loose to medium dense,moist) 1 SM 8 2 ML Brown to gray silt with a trace of fine sand and organic matter (medium stiff moist) 3 SM 43 4 5 5 6 H- w w u- 7 z CL a w 8 0 SM Gray silty fine sand with silt layers(loose to medium dense,wet) 9 10 """' 10 co 11 m Q N N E 12 SP Gray fine to medium sand with a trace of silt(loose to medium dense,wet) 4 , 13 Test pit completed at 13.0 feet on 12/17/97 Rapid ground water seepage observed at 12.0 feet Moderate ca,,ing observed between 8.0 and 12.0 feet 14 15 15 0 0 0 A 16 - 0 tO Note:See Figure A-2 for explanation of symbols LOG OF TEST PIT Ge0 Engineers FIGURE A-9 TEST DATA TEST PIT 5 DESCRIPTION Moisture Dry Content Derisity Blow Group Surface Elevation(ft.): 19.0 Lab Tests (%) (pcf) Count Samples Symbol 0 SP-SM Brown fine to coarse sand with silt and a trace of organic matter 0 (loose,moist) 2 SM 42 ML Brown silt with a trace of organic matter(medium stiff,very moist) 3 ML Orange-brown silt with fine sand(medium stiff,moist) 4 5 SP-SM Brown to gray fine to medium sand with silt and a trace of organic 5 matter(wood)(loose,wet) 6 H w w u_ 7 Z_ a 0 8 :: 9 10 10 c 11 v r E U 12 13 Lu Test pit completed at 13.5 feet on 12/17/97 14 Moderate ground water seepage observed at 10.0 feet Severe caging observed between 8.5 and 13.5 feet 0 15 15 0 0 0 A 16 - cn 0 Note:See Ficure A-2 for explanation of symbols ��s LOG OF TEST PIT GeoN�Engineers FIGURER-10 TEST DATA TEST PIT 6 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 20.0 Lab Tests (%) (pcf) Count Samples Symbol 0 ML Brown silt with a trace of fine sand(medium stiff,moist) 0 1 SM 38 2 ML Brown to gray silt(medium stiff moist) 3 4 5 5 6 Lu w w u- 7 z o_ w $ 0 9 10 SM Brown silty fine sand(loose,wet) 10 °o 11 m c lV N E 12 O 13 14 Test pit completed at 14.5 feet on 12/17/97 15 No Ground water seepage observed 15 No caving observed 0 0 0 16 - - 0 0 Lo Note:See Ficure A-2 for explanation of symbols LOG OF TEST PIT G e o.�Engineers FIGURE A-11 TEST DATA TEST PIT 7 DESCRIPTION MoistureContent Density Blow Group Surface Elevation(ft.): 21.0 Lab Tests (%) (pcf) Count Samples Symbol 0 ML Brown silt with a trace of fine sand and organic matter(medium 0 stiff moist) 1 SM 46 2 ML Brown to gray silt with a trace of fine sand(medium stiff,moist) 3 SM 43 4 5 5 6 SP-SM Gray fine to medium sand with silt and a trace of organic matter (loose,very moist) w w u_ 7 z_ IL IL 0 8 9 10 10 rn 11 v N N E U 12 o , 13 Test pit completed at 13.0 feet on 12/17/97 No ground water seepage observed Moderate ca-,ing observed between 8.0 and 13.0 feet 14 15 15 0 0 0 ci 16 0 0 to Note:See Figure A-2 for explanation of symbols LOG OF TEST PIT G e o Engineers FIGURE A-12 TEST DATA TEST PIT 8 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 16.0 Lab Tests (%) (pco Count Samples Symbol 0 NIL Brown silt with a trace of fine sand and organic matter(medium 0 stiff moist) 1 SM 37 NIL Gray to brown silt with a trace of fine to medium sand(medium 2 stiff moist to wet) 3 4 5 5 6 w w u- 7 Z ui H rL 6 NIL Gray silt with fine sand and a trace of organic matter(loose, vet) 9 10 SP Gray fine to medium sand with a trace of silt(loose,wet) 10 co 11 rn v N N E 12 13 Test pit completed at 13.5 feet on 12/17/97 14 Rapid ground water seepage observed at 4.0 feet Moderate caving observed between 1.0 and 6.0 feet 0 15 15 0 o 0 r� 16 - - Lo 0 `o Note:See Figure A-2 for explanation of symbols �� LOG OF TEST PIT G e o �Engineers FIGURE A-13 TEST DATA TEST PIT 9 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 17.0 Lab Tests (%) (pcf) Count Samples Symbol 0 SP-SM Brown fine to medium sand with silt and organic matter(loose, 0 moist) 1I. ML Gray to brown silt with fine sand and a trace of organic matter (medium stiff;moist) 2 3 SM 50 4 5 ML Gray to brown silt with fine to medium sand(medium stiff moist to 5 wet) 6 w w LL 7 z a w 6 9 SM Gray silty fine to medium sand(loose,wet) —10 Co 11 Q N cN C U 12 LU oTest pit completed at 12.5 feet on 12/17/97 13 Moderate ground water seepage observed at 5.3 feet Severe caving observed between 6.0 and 9.0 feet 14 15 15 0 0 0 0 16 - - 0 `D Note:See Figure A-2 for explanation of symbols LOG OF TEST PIT Geo !Engineers FIGURE A-14 TEST DATA TEST PIT 10 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 17.0 Lab Tests (%) (pcf) Count Samples Symbol 0 SM Brown silty sand(medium dense,moist) 0 1 SM 24 2 ML Gray to brown silt with a trace of fine to medium sand and organic matter(loose,moist) 3 SM 53 4 5 5 6 H w w u_ 7 z_ a_ ML Gray silt(medium stiff wet) w $ o 9 10 � 10 Co 11 Q N E 12 SM Gray silty fine to medium sand(loose,wet) o - 13 14 0 15 Test pit completed at 15.0 feet on 12/17/97 15 o No ground water seepage observed oNo ca,6ng observed 0 C, 16 to 0 to Note:See Ficure A-2 for explanation of symbols <A� LOG OF TEST PIT Geo��Engineers FIGURE A-15 TEST DATA TEST PIT 11 DESCRIPTION Moisture Dry Content Density Blow Group Surface Elevation(ft.): 20.0 Lab Tests (%) (pci) Count Samples Symbol 0 NIL Brown to gray silt with fine to coarse sand(medium7siltin 0 1 SM 23 NIL Brown to gray silt with lenses of fine to medium san the upper 2 feet(medium stiff,moist) 2 3 4 5 SP-SM Brown to gray sand with silt(loose,moist) 5 6 E- w w u z_ SP-SM Brown sand with silt and a trace of organic matter(wood)(loose, = moist to wet) H a Ld 8 :: 9 10 10 0 11 a i 12 Test pit completed at 12.5 feet on 12/17/97 13 Rapid ground water seepage observed at 11.5 feet Severe caging observed between 8.0 and 12.5 feet 14 15 15 , 16 — Note:See Figure A-2 for explanation of symbols LOG OF TEST PIT Geo Engineers FIGURE A-16 0.00 0.01 ...... .;..... ,: ;.... ..?.._ ..._. -- ........ ....................... 0.02 _... .__....__c ....................... .. i 0.04 - - .. 0.05 -- -- -- ...__ _. _ - -_....__..__— __ __ _ — __ _ --------. _ .— C U t: Z i Q J t _......... i j I 0.10 ? - -- -- --- --- i 0.11 -- - - -"--- - - -- - -- --- ---- - -- 0.12 _._.....___.._._ __..._._._...._.__. ._.._.._...--- _ -- - -_...... — _ -- _ — -._....-- ......._...... ........... 0.14 0.1 0.2 0.5 1 2 5 10 20 50 PRESSURE(Ibs/ft 2c 10 w c SAMPLE INITIAL INITIAL BORING DEPTH SOIL MOISTURE DRY DENSITY c? KEY NUMBER (FEET) CLASSIFICATION CONTENT (LBS/FT3) co N o B-1 6-8 Brown silt with sand (soft, moist) 37 74 45 CONSOLIDATION TEST RESULTS Geo Engineers 0 �' FIGURE A-17