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HomeMy WebLinkAboutSWP272870 4 JUL 17 2000 GEOTECHNICAL ENGINEERING STUDY ,. PROPOSED SAFEWAY FUELING STATION r' SOUTH THIRD STREET AND RAINIER AVENUE SOUTH RENTON, WASHINGTON 7 E-7323-2 February 23, 2000 PREPARED FOR SSOE, INC. i 'I Mitchell G. McGinnis ,+ Staff Geologist WAS �i Robert S. Levinso ,�` :- Principal a!" s 03107 'I Earth Consultants, Inc. ' 1805 - 136th Place Northeast, Suite 201 I Bellevue, Washington 98005 (425) 643-3780 Toll Free 1-888-739-6670 1 IMPORTANT INFORMATION ABOUT YOUR ' GEOTECHNICAL ENGINEERING REPORT ' More construction problems are caused by site subsur- technical engineers who then render an opinion about face conditions than any other factor As troublesome as overall subsurface conditions, their likely reaction to subsurface problems can be, their frequency and extent proposed construction activity, and appropriate founda- ' have been lessened considerably in recent years, due in tion design. Even under optimal circumstances actual large measure to programs and publications of ASFE/ conditions may differ from those inferred to exist, The Association of Engineering Firms Practicing in because no geotechnical engineer, no matter how the Geosciences. qualified, and no subsurface exploration program, no ' The following suggestions and observations are offered matter how comprehensive, can reveal what is hidden by to help you reduce the geotechnical-related delays, earth, rock and time. The actual interface between mate- cost-overruns and other costly headaches that can rials may be far more gradual or abrupt than a report occur during a construction project. indicates.Actual conditions in areas not sampled may differ from predictions. Nothing can be done to prevent the unanticipated, but steps can be taken to help minimize their A GEOTECHNICAL ENGINEERING impact. For this reason, most experienced owners retain their REPORT IS BASED ON A UNIQUE SET geotechnical consultants through the construction stage, to i den- tify variances, conduct additional tests which may be OF PROJECT-SPECIFIC FACTORS needed,and to recommend solutions to problems encountered on site. ' A geotechnical engineering report is based on a subsur- face exploration plan designed to incorporate a unique SUBSURFACE CONDITIONS set of project-specific factors. These typically include: the general nature of the structure involved, its size and CAN CHANGE ' configuration; the location of the structure on the site and its orientation; physical concomitants such as Subsurface conditions may be modified by constantly- access roads, parking lots, and underground utilities, changing natural forces. Because a geotechnical engi- and the level of additional risk which the client assumed veering report is based on conditions which existed at ' by virtue of limitations imposed upon the exploratory the time of subsurface exploration, construction decisions program. To help avoid costly problems, consult the should not be based on a geotechnical engineering report whose adequacy may have been affected by time. Speak with the geo- geotechnical engineer to determine how any factors ' technical consultant to learn if additional tests are which change subsequent to the date of the report may advisable before construction starts. affect its recommendations. Unless your consulting geotechnical engineer indicates Construction operations at or adjacent to the site and otherwise, your geotechnical engineering report should not natural events such as floods, earthquakes or ground- be used: water fluctuations may also affect subsurface conditions •When the nature of the proposed structure is and, thus, the continuing adequacy of a geotechnical changed, for example, if an office building will be report. The geotechnical engineer should be kept ' erected instead of a parking garage, or if a refriger- apprised of any such events, and should be consulted to ated warehouse will be built instead of an unre- determine if additional tests are necessary frigerated one: •when the size or configuration of the proposed GEOTECHNICAL SERVICES ARE structure is altered; PERFORMED FOR SPECIFIC PURPOSES •when the location or orientation of the proposed AND PERSONS structure is modified; ' •when there is a change of ownership, or Geotechnical engineers' reports are prepared to meet • for application to an adjacent site. the specific needs of specific individuals. A report pre- Geotechnical engineers cannot accept responsibility for problems pared for a consulting civil engineer may not be ade- which may develop if they are not consulted after factors consid- quate for a construction contractor, or even some other ' ered in their report's development have changed. consulting civil engineer. Unless indicated otherwise. this report was prepared expressly for the client involved and expressly for purposes indicated by the client. Use ' MOST GEOTECHNICAL "FINDINGS" by any other persons for any purpose, or by the client ARE PROFESSIONAL ESTIMATES for a different purpose, may result in problems. No indi- vidual other than the client should apply this report for its Site exploration identifies actual subsurface conditions intended purpose without first conferring with the geotechnical ' only at those points where samples are taken, when engineer. No person should apply this report for any purpose they are taken. Data derived through sampling and sub- other than that originally contemplated without first conferring sequent laboratory testing are extrapolated by geo- with the geotechnical engineer. ( Earth Consultants Inc. Grr,tr4uk-al FCn7{iniY•rti.G•duy;is Lti n Emirunnirntl ti,-e•niiti Lti t ' February 23, 2000 E-7323-2 SSOE, Inc. 3015 — 112th Avenue Northeast, Suite 101 Bellevue, Washington 98004 Attention: Mr. Stanley Paulus tDear Mr. Paulus: We are pleased to submit our report titled "Geotechnical Engineering Study, Proposed ' Safeway Fueling Station, South Third Street and Rainier Avenue South, Renton, Washington." This report presents the results of our field exploration, selective laboratory tests, and engineering analyses. The purpose and scope of our study was ' outlined in our January 27, 2000 proposal. Based on the results of our study, it is our opinion the proposed fueling station can be ' constructed generally as planned. Support for the proposed kiosk and fueling island canopy can be provided using conventional spread and continuous footing foundation systems bearing on competent native soil, existing competent fill or structural fill used ' to modify site grades. Slab-on-grade floors may be similarly supported. We appreciate this opportunity to be of service to you. If you have any questions, or ' if we can be of further assistance, please call. ' Respectfully submitted, EARTH CONSULTANTS, INC. ' Robert S. Levinson, P.E. Principal ' MGM/RSL/bkm ' 1805 136th Place N.E, Suite 201, Bellevue,Washington 98005 Bellevue(425)643-3780 FAX(425)746-0860 Toil Free(888) 739-6670 TABLE OF CONTENTS E-7323-2 PAGE INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 ' Pro*ect Descriation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 SITE CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ' Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Subsurface . . . . . . 2 Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 ' Laboratory Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 DISCUSSION AND RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 4 ' General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Site Preparation and General Earthwork . . . . . . . . . . . . . . . . . . . . . . . 4 Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 ' Slab-on-Grade Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Seismic Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Excavations and Slopes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 ' Site Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I . . . . . . . . . 10 Utility Support and Backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Fueling and Drive Area Pavements . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 ' LIMITATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Additional Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 ' APPENDICES ' Appendix A Field Exploration Appendix B Laboratory Test Results ILLUSTRATIONS ' Plate 1 Vicinity Map Plate 2 Boring Location Plan Plate 3 Utility Trench Backfill ' Plates Al Legend Plates A2 through A9 Boring Logs ' Plate B1 Grain Size Analyses ' Earth Consultants, Inc. ' GEOTECHNICAL ENGINEERING STUDY PROPOSED SAFEWAY FUELING STATION ' SOUTH THIRD STREET AND RAINIER AVENUE SOUTH RENTON, WASHINGTON ' E-7323-2 ' INTRODUCTION General ' This report presents the results of the geotechnical engineering study completed by Earth Consultants, Inc. (ECI) for the proposed Safeway fueling station at South Third Street and Rainier Avenue South, Renton, Washington. The general location of the site is shown on the Vicinity Map, Plate 1 . In July, 1996, we prepared a geotechnical engineering study for the Safeway Store east of the subject site. The purpose of this study was to further explore the subsurface conditions in the area of the proposed fueling station and based on the ' conditions encountered to develop geotechnical recommendations for the proposed site development. ' Project Description We understand it is planned to develop the site with a fueling station. The station ' construction will include a fueling island with an overhead canopy, two underground storage tanks, and a single-story attendant kiosk. The kiosk will have an approximate footprint of 286 square feet and will be one story in height. The building will be of relatively lightly loaded wood frame construction with ' a slab-on-grade floor. The fueling island canopy will be of steel construction. We estimate column loads for the canopy will be on the order of eighty (80) to one hundred (100) kips. 1 The underground storage tanks will be situated in the northwestern portion of the site and will require an excavation extending to a maximum depth of about fifteen (15) feet ' below existing grade. We anticipate the station will be constructed at or near existing grade. The fueling area will be surfaced with concrete pavement. The remainder of the site will be surfaced with asphalt-based pavements. 1 1 ' GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 2 ' If the above design criteria are incorrect or change, we should be consulted to review recommendations contained in this report. In any case, ECI should be retained to perform a general review of the final construction design. ' SITE CONDITIONS ' Surface The subject site is located approximately three hundred (300) feet east of the ' intersection of South Third Street and Rainier Avenue South in Renton (see Plate 1 , Vicinity Map). The site is currently used as a parking area for Safeway Store #1563 located approximately two hundred (200) feet east of the site. The site is bordered to ' the west by a car dealership, to the south by South Third Street and to the north and east by an existing asphalt-paved parking lot for the Safeway Store. ' The site is essentially flat with little discernible elevation change across the site and is paved with asphalt. ' Subsurface Subsurface conditions were evaluated by drilling two borings and reviewing subsurface ' data from our previous study completed for the existing Safeway Store. The approximate locations of the borings are shown on Plate 2. Please refer to the Boring Logs, Plates A2 through A9 for a detailed description of the conditions encountered at ' each location explored. A description of the field exploration methods is included in Appendix A. The following is a generalized description of the subsurface conditions encountered. In the area of the proposed fueling station as observed in Borings B-101 and B 102 we encountered seven and one half to nine feet of existing fill. Fill thickness to the north ' and east of the site ranged from two and one half to five feet thick as observed in Borings B-3 and B-5. The fill consists of loose to medium dense silty sand and sandy silt with varying amounts of gravel (Unified Soil Classifications SM and ML, ' respectively). The fill was characterized by the presence of angular gravel fragments, its loose consistency and the presence of trace organic debris. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 3 t The native soils typically consisted of interbedded sequences of medium dense to dense poorly graded sand with silt (SP-SM), poorly graded gravel with sand (GP) and poorly graded sand (SP) to the maximum exploration depth of twenty one and one half (21 .5) ' feet below existing grade. In Boring B-101 we encountered a five foot layer of loose to medium dense silty sand (SM) at ten (10) feet below existing grade. In addition, in Boring B-101 we encountered medium dense to dense sandy silt with varying amounts ' of organic wood debris. Groundwater Moderate to heavy groundwater seepage was encountered at each of the boring locations at depths ranging from five to fourteen (14) feet below grade. The observed seepage and mottling indicates perched and localized pockets of groundwater seepage may be encountered in site excavations. ' The contractor should be aware of the potential for seepage and that groundwater is not static. There will likely be fluctuations in the level depending on the season, amount of rainfall, surface water runoff, and other factors. Generally, the water level is higher and seepage rate is greater in the wetter winter months (typically October through May). ' Laboratory Testing Laboratory tests were conducted on representative soil samples to verify or modify the ' field soil classification and to evaluate the general physical properties and engineering characteristics of the soil encountered. Visual field classifications were supplemented by grain size analyses on representative soil samples. Moisture content tests were ' performed on all samples. The results of laboratory tests performed on specific samples are provided either at the appropriate sample depth on the individual boring logs or on a separate data sheet contained in Appendix B. It is important to note that these test results may not accurately represent the overall in-situ soil conditions. Our geotechnical recommendations are based on our interpretation of these test results and their use in guiding our engineering judgment. ECI cannot be responsible for the ' interpretation of these data by others. In accordance with our Standard Fee Schedule and General Conditions, the soil samples ' for this project will be discarded after a period of fifteen days following completion of this report unless we are otherwise directed in writing. Earth Consultants, Inc. ' GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 4 DISCUSSION AND RECOMMENDATIONS General Based on the results of our study, it is our opinion the proposed fueling station can be constructed generally as planned. Support for the kiosk and fuel island canopy can be ' provided using conventional spread and continuous footing foundation systems bearing on competent native soil, the existing competent fill or on structural fill used to modify existing site grades. Slab-on-grade floors may be similarly supported. ' Localized zones of loose soil were encountered at each of the boring locations. If loose soil is encountered at construction subgrade elevations, the loose soil should either be ' overexcavated and replaced with structural fill or compacted in-place to the requirements of structural fill as defined in the Site Preparation and Genera/Earthwork section of this report. Alternatively, the footings for the proposed kiosk may be ' extended through the loose soil. In addition, soil containing varying amounts of organic wood debris was observed in ' Boring B-101 at fifteen (15) to twenty (20) feet below existing grade. The organic content appeared to be less than 5 percent and should not adversely affect the proposed development. However, ECI should observe foundation and underground storage tank excavations to assess bearing soils. This report has been prepared for specific application to this project only and in a ' manner consistent with that level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area for the exclusive use of SSOE, Inc. and their representatives. No warranty, expressed or implied, is made. This report, in its entirety, should be included in the project contract documents for the information of the contractor. ' Site Preparation and General Earthwork The site should be stripped and cleared of foundations, surface vegetation and any other deleterious material. Existing utility pipes to be abandoned should be plugged or removed so they do not provide a conduit for water and cause soil saturation and ' stability problems. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 5 ' Localized zones of loose soil were encountered at each of the boring locations. If loose soil is encountered at construction subgrade elevations, the loose soil should either be overexcavated and replaced with structural fill or compacted in-place to the requirements of structural fill as defined in the Site Preparation and Genera/Earthwork section of this report. Alternatively, the footings for the proposed kiosk may be extended through the loose soil. In addition, soil containing varying amounts of organic wood debris was observed in Boring B-101 at fifteen (15) to twenty (20) feet below existing grade. The organic content appeared to be less than 5 percent and should not adversely affect the proposed development. However, ECI should observe foundation and underground storage tank excavations to evaluate exposed soils. ' It may be possible to crush the existing site pavements for use as structural fill materials. Materials reclaimed by crushing and used as fill should have a maximum size ' of three inches and should be mixed with soil to provide a well graded material. Following the stripping operation, the ground surface where structural fill, foundations, or slabs are to be placed should be observed by a representative of ECI. Proofrolling may be necessary in order to identify soft or unstable areas. Proofrolling should be performed under the observation of a representative of ECI. Soil in loose or soft areas, ' if recompacted and still excessively yielding, should be overexcavated and be replaced with structural fill to a depth that will provide a stable base beneath the general structural fill. The optional use of a geotextile fabric placed directly on the ' overexcavated surface may help to bridge unstable areas. Structural fill is defined as compacted fill placed under buildings, roadways, slabs, ' pavements, or other load-bearing areas. Structural fill under floor slabs and footings should be placed in horizontal lifts not exceeding twelve 0 2) inches in loose thickness and compacted to a minimum of 90 percent of its laboratory maximum dry density determined in accordance with ASTM Test Designation D-1557-91 (Modified Proctor). The fill materials should be placed at or near their optimum moisture content. Fill under ' pavements and walks should also be placed in horizontal lifts and compacted to 90 percent of maximum density except for the top twelve (12) inches which should be compacted to 95 percent of maximum density. Earth Cansuhants, Inc. GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 6 t During dry weather, most soils that are compactible and non-organic can be used as structural fill. Based on the results of our review, the on-site soils appear to be near their optimum moisture content and should be suitable for use in their present condition as structural fill, provided the grading operations are conducted during dry weather. However, the site soils have greater than 5 percent fines passing the No. 200 sieve. Soil with fines in this range will degrade if exposed to excessive moisture, and ' compaction and grading will be difficult if the soil moisture increases significantly above its optimum condition. ' If the site soil is exposed to moisture and cannot be adequately compacted, then it may be necessary to import a soil that can be compacted. During dry weather, any non- organic compactible soil with a maximum grain size of six inches can be used. Fill for ' use during wet weather should consist of a fairly well graded granular material having a maximum grain size of six inches and no more than 5 percent fines passing the No. 200 sieve based on the minus 3/4-inch fraction. A contingency in the earthwork budget should be included for this possibility. Foundations ' Based on the results of our study, it is our opinion the proposed kiosk and fueling island canopy can be supported on conventional spread and continuous footing foundation ' systems bearing on competent native soil, existing competent fill or structural fill used to modify site grades. Localized zones of loose soil were encountered at each of the boring locations. If loose soil is encountered at construction subgrade elevations, the loose soil should either be overexcavated and replaced with structural fill or compacted in-place to the ' requirements of structural fill as defined in the Site Preparation and Genera/Earthwork section of this report. Alternatively, the footings for the proposed kiosk may be extended through the loose soil. Soil containingvarying amounts of organic wood debris was observed in Boring B-101 Y 9 9 at fifteen (15) to twenty (20) feet below existing grade. The organic content appeared to be less than 5 percent and should not adversely affect the proposed development. However, ECI should observe foundation and underground storage tank excavations to ' evaluate exposed soils. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 7 1 For frost protection, exterior foundation elements should be placed at a minimum depth of eighteen (18) inches below final exterior grade. Interior spread foundations can be placed at a minimum depth of twelve (12) inches below the top of slab, except in ' unheated areas, where interior foundation elements should be founded at a minimum depth of eighteen (18) inches. ' With foundation support obtained as described, for design, an allowable soil bearing capacity of two thousand five hundred (2,500) pounds per square foot (psf) can be used for the competent native soil or existing fill, and newly placed structural fill. ' Continuous and individual spread footings should have minimum widths of eighteen (18) and twenty-four (24) inches, respectively. Loading of this magnitude would be provided with a theoretical factor-of-safety in excess of three against actual shear ' failure. For short-term dynamic loading conditions, a one-third increase in the above allowable bearing capacities can be used. ' With structural loading as expected, total settlement of about one inch is anticipated with differential movement of about one-half inch. Most of the anticipated settlements should occur during construction as dead loads are applied. Horizontal loads can be resisted by friction between the base of the foundation and the supporting soil and by passive soil pressure acting on the face of the buried portion of ' the foundation. For the latter, the foundation must be poured "neat" against the competent native soils or backfilled with structural fill. For frictional capacity, a coefficient of .40 can be used. For passive earth pressure, the available resistance can ' be computed using an equivalent fluid pressure of three hundred fifty (350) pcf. These lateral resistance values are allowable values, a factor-of-safety of 1 .5 has been included. As movement of the foundation element is required to mobilize full passive ' resistance, the passive resistance should be neglected if such movement is not acceptable. ' Footing excavations should be observed by a representative of ECI, prior to placing forms or rebar, to verify that conditions are as anticipated in this report. Slab-on-Grade Floors Slab-on-grade floors may be supported on competent native soil, existing competent ' fill, or on structural fill used to modify site grades. Disturbed subgrade soil must either be recompacted or replaced with structural fill. ' Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 8 ' The slab should be provided with a minimum of four inches of free-draining sand or gravel. In areas where slab moisture is undesirable, a vapor barrier such as a 6-mil plastic membrane may be placed beneath the slab. Two inches of damp sand may be placed over the membrane for protection during construction and to aid in curing of the concrete. ' Seismic Design Considerations The Puget Lowland is classified as a Seismic Zone 3 in the 1997 Uniform Building Code (UBC). Earthquakes occur in the Puget Lowland with regularity; however, the majority of these events are of such low magnitude they are not felt without instruments. Large earthquakes do occur, as indicated by the 1949, 7.2 magnitude earthquake in the ' Olympia area and the 1965, 6.5 magnitude earthquake in the Midway area. There are three potential geologic hazards associated with a strong motion seismic event at this site: ground rupture, liquefaction, and ground motion response. Ground Rupture: The strongest earthquakes in the Puget Lowland are widespread, ' subcrustal events, ranging in depth from thirty (30) to fifty-five (55) miles. Surface faulting from these deep events has not been documented to date. Therefore, it is our opinion that the risk of ground rupture at this site during a strong motion seismic event ' is negligible. Liquefaction: Liquefaction is a phenomenon in which soils lose all shear strength for ' short periods of time during an earthquake. Groundshaking of sufficient duration results in the loss of grain to grain contact and rapid increase in pore water pressure, causing the soil to behave as a fluid. To have a potential for liquefaction, a soil must ' be cohesionless with a grain size distribution of a specified range (generally sand and silt); it must be loose; it must be below the groundwater table; and it must be subject to sufficient magnitude and duration of groundshaking. The effects of liquefaction may ' be large total and/or differential settlement for structures founded in the liquefying soils. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 9 In our opinion, the potential for liquefaction induced settlement of the soils underlying the site should be negligible provided the recommendations in this report are followed. ' Ground Motion Response: The 1997 UBC Earthquake regulations contain a static force procedure for design base shear calculations. Based on the encountered soil conditions it is our opinion soil profile type Sp, Stiff Soil, as defined in Table 16-J should be used ' to characterize the site soils. Excavations and Slopes The following information is provided solely as a service to our client. Under no circumstances should this information be interpreted to mean that ECI is assuming ' responsibility for construction site safety or the contractor's activities; such responsibility is not being implied and should not be inferred. ' The inclination of temporary slopes is dependent on several variables, including the height of the cut, the soil type and density, the presence of groundwater seepage, construction timing, weather, and surcharge loads from adjacent structures, roads and equipment. In no case should excavation slopes be greater than the limits specified in local, state (WISHA) and Federal (OSHA) safety regulations. In our opinion, the loose to medium dense soils underlying the site would be classified as Type C based on ' Washington Administrative Code (WAC) 296, Part N. Temporary cuts greater than four feet in height in Type C soils should be sloped at an inclination of 1 .5H(Horizontal):1 V(Vertical). The underlying dense to very dense native soils would ' be classified as Type A soils. Temporary cuts greater than four feet in height in Type A soils should be sloped at an inclination of 0.75 H:1 V. Because of the many variables involved, the inclination of temporary excavation slopes should be evaluated during construction, as the actual soil conditions become more apparent. If slopes of this inclination, or flatter, cannot be constructed, temporary shoring may ' be necessary. Shoring will help protect against slope or excavation collapse, and will provide protection to workers in the excavation. If temporary shoring is required, we will be available to provide shoring design criteria. Earth Consultants, Inc, ' GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 10 Site Drainage Groundwater seepage was encountered at each of the boring locations at depths ' ranging from five to fourteen (14) feet below grade. As such, groundwater seepage will likely be encountered in the underground storage tank and utility excavations. If seepage is encountered, the bottom of the excavation should be sloped to one or more shallow sump pits. The collected water can then be pumped from these pits to a positive and permanent discharge, such as a nearby storm drain. Depending on the magnitude of such seepage, it may also be necessary to connect the sump pits by a ' system of connector trenches. The appropriate locations of subsurface drains, if needed, should be established during grading operations by ECI's representative at which time the seepage areas, if present, may be more clearly defined. ' During construction, the site must be graded such that surface water is directed off the site. Water must not be allowed to stand in areas where buildings, slabs or pavements are to be constructed. Loose surfaces should be sealed at night by compacting the ' surface to reduce the potential for moisture infiltration into the soils. Final site grades must allow for drainage away from the building foundations. The ground should be sloped at a gradient of three percent for a distance of at least ten feet away from the ' building, except in paved areas, which can be sloped at a gradient of two percent. Utility Support and Backf_ill ' Based on the soil conditions encountered, the soils expected to be exposed by utility excavations should provide adequate support for utilities and the underground storage tanks. Utility trench backfill is a primary concern in reducing the potential for settlement along ' utility alignments, particularly in pavement areas. It is important that each section of utility line be adequately supported in the bedding material. The material should be hand tamped to ensure support is provided around the pipe haunches. Fill should be ' carefully placed and hand tamped to about twelve inches above the crown of the pipe before heavy compaction equipment is brought into use. The remainder of the trench backfill should be placed in lifts having a loose thickness of less than twelve inches. ' A typical trench backfill section and compaction requirements for load supporting and non-load supporting areas is presented on Plate 3. Earth Consultants, Inc. ' GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 11 Existing utility pipes to be abandoned should be plugged or removed so that they do not provide a conduit for water and cause soil saturation and stability problems. Fueling and Drive Area Pavements The adequacy of site pavements is related in part to the condition of the underlying subgrade. To provide a properly prepared subgrade for pavements, the subgrade should be treated and prepared as described in the Site Preparation and General Earthwork section of this report. This means at least the top twelve (12) inches of the subgrade should be compacted to 95 percent of the maximum dry density (per ASTM D-1557- 91). It is possible that some localized areas of soft, wet or unstable subgrade may still exist after this process. Therefore, a greater thickness of structural fill or crushed rock may be needed to stabilize these localized areas. The following pavement section for lightly-loaded areas can be used: • Two inches of asphalt concrete (AC) over four inches of crushed rock base (CRB) material, or • Two inches of AC over three inches of asphalt treated base (ATB) material. ' • Four inches of Portland concrete cement (PCC). For heavier truck traffic areas, the following sections can be used: • Three inches of AC over six inches of CRIB material, or ' • Three inches of AC over four and one half inches of ATB material. • Six inches of PCC. Pavement materials should conform to WSDOT specifications. The use of a Class B asphalt mix is suggested. Earth Consultants, Inc. ' GEOTECHNICAL ENGINEERING STUDY SSOE, Inc. E-7323-2 February 23, 2000 Page 12 LIMITATIONS Our recommendations and conclusions are based on the site materials observed, selective laboratory testing and engineering analyses, the design information provided us and our experience and engineering judgment. The conclusions and recommendations are professional opinions derived in a manner consistent with that ' I level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. No warranty is expressed or implied. ' The recommendations submitted in this report are based upon the data obtained from the borings. Soil and groundwater conditions between borings may vary from those encountered. The nature and extent of variations between our exploratory locations may not become evident until construction. If variations do appear, ECI should be requested to reevaluate the recommendations of this report and to modify or verify them in writing prior to proceeding with the construction. Additional Services ' As the geotechnical engineer of record, ECI should be retained to perform a general review of the final design and specifications to verify that the earthwork and foundation recommendations have been properly interpreted and implemented in the design and in the construction specifications. ECI should also be retained to provide geotechnical services during construction. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. We do not accept responsibility for the ' performance of the foundation or earthwork unless we are retained to review the construction drawings and specifications, and to provide construction observation and testing services. i Earth Consultants, Inc. ' Non-Load Supporting Floor Slab or Areas Roadway Areas ° Varies 95 0 o , 85 95 : 1 Foot Minimum Backfill 8o 90 Varies PIPE c' -0 04` ••'off°- °'b.oso '.'0'0:� Varies Bedding °'o.o�.Qo:�.°:. o o,. od.Q°°. °. 0.0o Q.o..0:0 °'p o:�Q�ooOo�000°'o80 o000Oo0ogQ0�•000Q'o O:DO�vO ' LEGEND: Asphalt or Concrete Pavement or Concrete Floor Slab ,au y fryer: P O° o o o ° o .1 Base Material or Base Rock kfill' Compacted On-Site Soil or Imported Select Fill Bat P Material as Described in the Site Preparation of the General Earthwork Section of the Attached Report Text. Minimum Percentage of Maximum Laboratory Dry Density as 95 Determined by ASTM Test Method D 1557-78 (Modified Proctor), Unless Otherwise Specified in the Attached Report Text. O ° Bedding Material; Material Type Depends on Type of Pipe and Laying Conditions. Bedding Should Conform to the Manufacturers 0. Recommendations for the Type of Pipe Selected. TYPICAL UTILITY TRENCH FILL Earth Consultants Inc. Proposed Safeway Fueling Station Renton, Washington Proj. No. 7323-2 Drwn. GLS Date Feb. 2000 Checked MGM Date 2/22100 Plate 3 ' APPENDIX A ' FIELD EXPLORATION E-7323-2 Our field exploration was performed on February 14, 2000. Subsurface conditions at ' the site were explored by drilling two borings to a maximum exploration depth of twenty one and one half (21 .5) feet below existing grade. The borings for this study were drilled by Associated Drilling using a truck-mounted drill rig. ' We also reviewed two logs from our geotechnical engineering study for the existing Safeway Store. Approximate boring locations were estimated by pacing from site features depicted on the site plan provided by the client. The elevations were estimated relative to one ' another. The locations and elevations of the borings should be considered accurate only to the degree implied by the method used. These approximate locations are ' shown on the Boring Location Plan, Plate 2. The field exploration was continuously monitored by an engineer from our firm who ' classified the soils encountered, maintained a log of each boring, obtained representative samples, measured groundwater levels, and observed pertinent site features. The samples were visually classified in accordance with the Unified Soil Classification System that is presented on Plate Al, Legend. Representative soil samples were placed in closed containers and returned to our laboratory for further examination and testing. Logs of the borings are presented on Plates A2 through A9. The final logs represent our interpretations of the field logs and the results of the laboratory examination and ' tests of field samples. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. ' The borings were drilled using hollow stem augers. In each boring, Standard Penetration Tests (SPT) were performed at selected intervals in general accordance with ASTM Test Designation D-1586. The split spoon samples were driven with a one ' hundred forty (140) pound hammer freely falling thirty (30) inches. The number of blows required to drive the last twelve (12) inches of penetration are called the "N- value". This value helps to characterize the site soils and is used in our engineering ' analyses. These results are recorded on the boring logs at the appropriate sample depths. Earth Consultants, Inc. MAJOR DIVISIONS GRAPH LETTER TYPICAL DESCRIPTION ' SYMBOL SYMBOL Gravel C3 < GW Well-Graded Gravels, Gravel-Sand And Clean Gravels ro o Q o O o gW Mixtures, Little Or No Fines ' Gravelly (little or no fines) r M GP Poorly-Graded Gravels,Gravel- Coarse Soils ' ' ' gp Sand Mixtures, Little Or No Fines Grained Soils More Than GM Silty Gravels,Gravel-Sand- 50% Coarse Gravels With gm Silt Mixtures ' Fraction Fines(appreciable Retained On amount of fines) GC Clayey Gravels,Gravel-Sand- No. 4 Sieve gC Clay Mixtures Sand o v� o SW Well-Graded Sands, Gravelly And Clean Sand c c v c v SW Sands, Little Or No Fines Sandy (little or no fines) ::?:y::;::►.:;. _<;q;,.: More Than VH Poorly-Graded Sands, Gravelly SoilsSands, Little Or No Fines 50% Material Larger Than More Than No.200 Sieve 50% Coarse Silty Sands, Sand-Silt Mixtures Size Sands With ' Fraction Fines(appreciable Sieve ing No.4 amount of fines) Sc Clayey Sands, Sand-Clay Mixtures .. .. ..........IX . Inorganic Silts&Very Fine Sands,Rock Flocr,Silty- ' Clayey Fine Sands;Clayey Silts w/ Slight Plasticity Fine Silts Inorganic Clays Of Low To Medium Plasticity, Grained And Liquid Limit Soils Clays Less Than 50 � Gravelly Clays, Sandy Clays, Silty Clays, Lean Organic Silts And Organic Silty Clays Of Low Plasticity Inorganic Silts, Micaceous Or Diatomaceous Fire More Than Sand Or Silty Soils 50% Material Silts Liquid Limit ' Smaller Than Plasticity, Clays Of High Clays Greater Than 50 CH No.200 Sieve Ch Plasticity, Fat Clays Size j OH Organic Clays Of Medium To High Oh Plasticity. Organic Silts OR,y"' Peat, Humus, Swamp Soils Highly Organic Soils r `r r 'Pt With High Organic Contents Topsoil y y y y Humus And Duff Layer Fill Highly Variable Constituents The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. ' DUAL SYMBOLS we used to Indicate borderline soil classification. C TORVANE READING,tsf I 2' O.D. SPLIT SPOON SAMPLER qu PENETROMETER READING,tsf W MOISTURE, %dry weight 24' I.D. RING OR SHELBY TUBE SAMPLER P SAMPLER PUSHED SAMPLE NOT RECOVERED WATER OBSERVATION WELL ' pcf DRY DENSITY,lbs. per cubic ft. ILL LIQUID LIMIT, % SL DEPTH OF ENCOUNTERED GROUNDWATER PI PLASTIC INDEX DURING EXCAVATION ' 1 SUBSEQUENT GROUNDWATER LEVEL W/DATE ' E Earth Consultants Inc. LEGEND Itl� /-�vk't lu�ir�I1_i�jiiu cry.(Kxrkrb`i„s 141��.u�>tu­'I.'iSi visa, FProj. o.7 323-2 Date Feb. '00 Plate Al Boring Log Sheet of Project Name: 1 2 Proposed Safeway Fueling Station �Comple�honDate: Boring No.: Job No. Logged by: Start Date:7323-2 WRJ 2/14/00 B-101 Drilling Method: Sampling Method: Drilling Contactor: SPT Associated HSA ' Ground Surface Elevation: Hole Completion: Monitoring 100' Well El Piezometer ® n Abandoed,sealed with bentonite ❑ Surface Conditions: Parking Lot: 1.5'"-2"Asphalt Surface ' W No. L m t a U n°General Blows cL E � E rn E Notes M Ft. c`9 cn cn SM Brown silty fine to medium SAND, medium dense, moist(Fill) 13.0 1 2 ' 11.9 3 22 ' 4 5 15.5 14 6 7 9.6 SP-SM Brown poorly graded SAND with silt and gravel, medium dense, ' 26 8 moist e 9 13.4 0. 10 -becomes loose and wet 10 e o 11 -contains interbedded sift layers 0 12 ' v 13 o ° 14 0 1 103.5 ° 15 ML Black sandy SILT, dense, moist 49' 16 -contains organics 17 ' a 18 a 0 19 -contains wood fragments w Boring Log Furth Consultants Inc. Proposed Safeway Fueling Station ' r xr-{nik al FnRnwr+s.G-cic�41 Fxivi""I�'Mi k.-trntt�n Renton, Washington c� Plate A2 z Proj. No. 7323-2 own. GLS Date Feb. 2000 Checked WRJ Date 2/24/0 ' Subsurface conditions depicted represent our observations at the time and location of this e�loratory hole, modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibility for the use or interpretation by others of information presented on this log. Boring Log t Sheet of Project Name: 2 2 Proposed Safeway Fueling Station Job No. Logged by: Start Date: Completion Date: Boring No.: ' 7323-2 WRJ 2/14/00 2/14/00 B-101 Drilling Method: Sampling Method: Drilling Contactor: g SPT Associated HSA ' Hole Completion' Ground Surface Elevation: 100� ❑ Monitoring Well ❑ Piezometer ® Abandoned,sealed with bentonde No. `—' o L w U) o General I Blows a E o U_ E CL ? E Ft. C7 rn in u'i Z9.4 ML Black sandy SILT,dense, moist 24 zt _i -contains wood fragments zz 1 23 ' za 14.1 _ 25 GP-GM Brown poorly graded GRAVEL with sand,dense,wet 43 zs -contains wood debris Boring terminated at 26.5 feet below e)asting grade. Groundwater seepage encountered at 14.0 feet during drilling. Boring backfilled with bentonite and cuttings. ' NOTE: Elevations estimated, relative to each other_ o a 0 ' w Boring Log N Earth Consultants Inc. Proposed Safeway Fueling Station ' Gc.Kxraymh-alFn�hircyti.Gf^kGt�nR.FiivSrc+riii.rnral:Airnn+� Renton,Washington O t7 Z Proj.No. 7323-2 Dwn. GLS Date Feb. 2000 Checked WRJ Date 2/24/00 Plate A Subsurface conditions depicted represent our observations at the time and location of this e)loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibility for the use or interpretation by others of information presented on this log. Boring Log Sheet of Project Name: 1 2 Proposed Safeway Fueling Station Start Date: Completion Date: Boring No.: Job No. Logged by: 2/14/00 B 102 ' 7323-2 WRJ lung M 0 Dulling Method: Sampling Method: Drilling Contactor: HSA SPT Associated ' Ground Surface Elevation: Hole Completion: ❑ Monitoring Well ❑ Piezometer ® Abandoned,sealed with bentonite 100' Surface conditions: Parking Lot: 1.5',-2 Asphalt Surface W No. r t a ' General Blows E y iL E cn E Notes M Ft. 0 rn in _ `n SM Brown silty fine to medium SAND with gravel, medium dense, moist 14.2 (Fill) 1 2 ' 14.9 3 t39 4 33.3 5 ML Brown sandy SILT, loose, moist(Fill) 6 6 -iron o)dde staining 7 -contains interbedding layers of silt 38.4 8 5 9 SP-SM Brown poorly graded SAND with silt and gravel, dense,wet ' 11.3 '. 10 43 ° 11 ° 12 o ° ' 13 14 11.4 15 -contains interbedding sand layers 26 ° 16 -medium to coarse grained sand 17 o •a 18 0 19 c9 ° o ° Boring Log IOU Earth Consultants Inc. Proposed Safeway Fueling Station ' r Renton, Washington O Gc[rrct ink al FnR�nM�Ge-!ik�tti+��`Fnvl rt.unrnrnl tiilrntl O Z Date Feb. Checked WRJ Date 2/24/00 Plate A4 mProj.No. 7323-2 Dwn. GLS Subsurface conditions depicted represent our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibility for the use or interpretation by others of information presented on this log. Boring Log Sheet of ' Project Name: 2 2 Proposed Safeway Fueling Station Job No. Logged by: Start Date: Completion Date: Boring No.: 7323-2 WRJ 2/14/00) 2/14/00 B-102 ' Drilling Contactor Drilling Method: Sampling Method: SPT Associated HSA ' Hole Completion'. Ground Surface Elevation: 100, ❑ Monitoring Well ❑ Piemmeter ® Abandoned,sealed with bentonite �/y No- .2 a t n U -6 General Blows m E ani LL. E cn E Notes (%) Ft. c7 rn 0 in 22.2 SP-SM Brown poorly graded SAND,dense,wet,gravel content decreases 53 21 ' -coarse grained sand Boring terminated at 21.5 feet below e)asting grade. Groundwater seepage encountered at 5.0 feet during drilling. Boring backfilled with bentonite and cuttings. t o 0 a 0 0 ' w Boring Log Furth Consultants Inc. Proposed Safeway Fueling Station Renton,Washington 0 7323-2 DHrn. GLS J�D�atFeb. 2000 Checked WRJ Date 2/24/00 Plate AS m Proj.No. ' Subsurface conditions depicted represent our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibility for the use or interpretation by others of information presented on this log. ' Boring Log Sheet of Project Name: 1 2 Proposed Saf way Store Job No. Logged by. Start Date: �611 on Date: Boring No.: 7323 RAC 6 12 96 96 B-3 Drilling Contactor: Drilling Method: Sampling Method: t Associated Drilling HSA SPT Ground Surface Elevation: Hole Completion: ❑ Monitorin Well ❑ Piezometer ® Abandoned,sealed with bentonite ' ° • — Surface Conditions: W No. r o } C4 o Blow3 a E a + E N E N Ft L ] 4 7 � N N N ' SM (Approximately 2"Asphalt over 4-6" Gravel Base) FILL: Brown to black silty fine to medium SAND, loose, moist 1 ' 2 13.8 13 3 -becomes medium dense, moist to wet ' 4 5L[]�_P-SN Gray porly graded fine to medium SAND with gravel, dense, moist 5.3 32 ° 6 7 -becomes very dense 8 3.9 75 Q. 0 9 10 = GP groundwatter tabledes to poody raed GRAVEL with sand, dens ,en countered at approximately epwater bearing •. • 6.7 as •�• 11 • - - • • 12 ___ -- --- --- SP Grades to poorly graded fine to coarse SAND with gravel, dense, ° water bearing !' 13 15.9 46 °oe 'o. ! ° 14 !O e Q o _ O p e 15 !° 7.9 39 .o P 16 ° O ° P o 17 0 o- ° tr° 18 'P O O m 19 c o Boring Log Earth Consultants Inc. Proposed Safeway Store N m MWUUVr=tW Renton, Washington ' r J Plate A6 m Proj. No. 7323 Dwn. GLS Data June '96 Checked RAC Date 6/25/96 Subsurface conditions depicted represent our observations at the time and location of this exploratory hole,modified by engineering tests, analvcls and iudoment. Thev are not necessarily representative of other times and locations.We cannot accept responsibility for the use or ' Boring Log Sheet of Project Name: Proposed Safeway Store 2 2 Job No. Logged by: Start Date: Completion Date: Boring No.: 7323 RAG 6 12 96 6 12 96 B-3 Drilling Contactor: Drilling Method: Sampling Method: Associated DrillingHSA SPT Ground Surface Bevation: Hole Completion: ❑ MonitoringWell ❑ Piezometer ® Abandoned,sealed with bentonite ' e No. o L v► o w BIOWS a E a } E N E O y Vl N " -increasing sand content 18.4 31 ;'o::01 Boring terminated at 21.5 feet below existing grade. Groundwater ' table encountered at 10.0 feet during drilling. Boring backfilled with cuttings, bentonite and asphalt patch. N Boring Log Earth Consultants Inc. Proposed Safeway Store + `a'Sdcr g" Renton,Washington r ' Proj.No. 7323 Dwn. GLS Data June 96 Checked RAG Date 6/25/96 Plate A7 m Subsurface conditions depicted represent our observations at the time and location of this exploratory hole,modified by engineering tests, analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibility for the use or ' Boring Log Project Name: Sheet of Proposed Safeway Store 1 2 Job No. Logged by: Start Date: Completion Date: Boring No.: 7323 RAC 6 12 96 6 12 96 B—rJ Drilling Contactor: Drilling Method: Sampling Method: Associated DrillingHSA SPT Ground Surface Elevation: Hole Completion: ❑ Monitorin Well ❑ Piezometer ® Abandoned,sealed with bentonite ' ° — a — Surface Conditions: No. o L rn o W Blow 4 E d +' E N E (96) Ft ' ' a 'L > > OL N Vf Vl ' SM (Gravel and Duff to approximately 2-4" FILL Brown silty fine to medium SANDwith gravel, loose, moist 1 ' 2 a ML Gray sandy SILT, loose,wet, some mottling 29.8 g ' 4 5 SM Grades to silty fine to medium SAND, loose, wet, trace gravel ' 25.0 4 6 ' 7 SP Grades to poorly graded fine to medium SAND with gravel, loose, Q moist, small sample recovery P S 5.1 6 P ♦- t 's 9 GP Grades to poor) graded GRAVEL with sand,medium dense,water '.� 10 bearing, groundywater table encountered at approximately 9.5' ' . • 11.0 13 •,• 11 12 10.5 14 13 -increasing coarse sand content ' s •� • 14 •1 • .... -- ---- SP Grades to poorly graded medium to coarse SAND with gravel, o 0 15 medium dense,water bearing 18 c o c 0 16 o ° o q 17 O P O 18 q- •p P ' 1O LD q N Boring Log M Earth Consultants Inc. Proposed Safeway Store N GCvkw,,c'ErOrx=� Renton, Washington r Proi. No. 7323 Dwn. GLS Date June'96 Checked RAC Date 6/25/96 Plate A ' J m Subsurface conditions depicted represent our observations at the time and location of this exploratory hole,modified by engineering tests, analysis and judgment. The are not necessarily representative of other times and locations.We cannot accept responsibility for the use or ' Boring Log Project Name: Sheet of Proposed Safeway Store 2 2 ' Job No. Logged by: Start Date: Completion Date: Boring No.: 7323 RAC 6 12 96 6 12 96 B-5 Drilling Contactor: Drilling Method: Sampling Method: Associated Drilling HSA SPT Hole Completion: Ground Surface Elevation: ❑ Monitoring Well ❑ Pieiometer ® Abandoned, sealed with bentonite t u _ e No. o t H o w Blows a E a t E ti E (96) Ft. a m u. a D L H O N N 120 2221 Boring terminated at 21.5 feet below existing grade. Groundwater ' table encountered at 9.5 feet during drilling. Boring backfilied with cuttings and bentonite. LO Ln N LO Boring Log r1 Earth Consultants Inc. Proposed Safeway Store N I ' ceokxlril®1 C i D7v4of1R1ClY&i Sd-ul o• Renton, Washington r ' Proj.No. 7323 Dwn. GLS Date June '96 Checked RAC Date 6/25/1 Plate A9 m Subsurface conditions depicted represent our observations at the time and location of this exploratory hole,modified by engineering tests, analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibility for the use or i.....r...toti—by nth.—of imnrmntinn presented on this loa. ' APPENDIX B LABORATORY TEST RESULTS E-7323-2 Earth Consultants, Inc. • •Go MIN IMMIN MINE MEN IN NIEMEN MEN IN LvA 10111111101111111 OMEN - MIXIIN _ MMIN mom WIN WEE 11001 ,ME MOM MEN MIN EMU= ,020m. 01 MINE MEN mm 01011 INS OZONE" IME mom MWEIME MEN 10101 Me ME ON mm ME 0100 ME m ME immommm Emu IME NO 110111 mom NE No IN No OEM NEE DESCRIPTION �m Brown poorly�_graded SAND with silt & ,gravel Brown poorly graded ' DISTRIBUTION E-7323-2 ' 4 Copies SSOE, Inc. 3015 - 112t`' Avenue Northeast, Suite 101 ' Bellevue, Washington 98004 Attention: Mr. Stanley Paulus t ' 1 Copy Bush, Roed and Hitchings 2009 Minor Avenue East Seattle, Washington 98102-3513 ' Attention: Mr. Pedro DeGuzman 1 1 Earth Consultants, Inc.