Geotechnical Investigation Spring Filling Station Mantua, Utah

Transcription

1 8143 South 2775 East, South Weber, Utah Phone (801) Geotechnical Investigation Spring Filling Station Mantua, Utah Christensen Geotechnical Project No June 8, 2017 Prepared for: Brigham City Corporation c/o Jones & Associates Consulting Engineers 1716 E 5600 S South Ogden, UT 84403

2 8143 South 2475 East South Weber, Utah Phone: Prepared for: Brigham City Corporation c/o Jones & Associates Consulting Engineers 1716 E 5600 S South Ogden, UT Geotechnical Investigation Spring Filling Station Mantua, Utah Christensen Geotechnical Project No Prepared by: 6/7/17 Mark Christensen P.E. Principal Christensen Geotechnical 8143 South 2475 East South Weber, UT (801) June 8, 2017

3 TABLE OF CONTENTS 1.0 EXECUTIVE SUMMARY INTRODUCTION PURPOSE AND SCOPE OF WORK PROJECT DESCRIPTION METHOD OF STUDY SUBSURFACE INVESTIGATION LABORATORY TESTING ENGINEERING ANALYSIS GENERALIZED SITE CONDITIONS SURFACE CONDITIONS SUBSURFACE CONDITIONS Soils Groundwater Conditions GEOLOGIC CONDITIONS SUFICIAL GEOLOGY FAULTING SEISMIC DESIGN CRITERIA LIQUEFACTION ENGINEERING ANALYSIS AND RECOMMENDATIONS GENERAL CONCLUSIONS EARTHWORK General Site Preparation and Grading Soft Soil Stabilization Excavation Stability Structural Fill and Compaction FOUNDATIONS SETTLEMENT EARTH PRESSURES AND LATERAL RESISTANCE CONCRETE SLAB-ON-GRADE CONSTRUCTION MOISTURE PROTECTION AND SURFACE DRAINAGE PAVEMENT Traffic Copyright 2017 Christensen Geotechnical i Spring Filling Station

4 6.8.2 Existing Pavement Condition Pavement Sections Pavement Conclusions CLOSURE LIMITATIONS ADDITIONAL SERVICES REFERENCES CITED APPENDICES Appendix A Appendix B Appendix C Plate A-1...Site Vicinity Map Plate A-2...Exploration Location Map Plate B-1 to B-4...Boring Logs Plate B-5...Soil Symbols Description Key Plate C-1...Atterberg Limits Test Results Plate C-2...Consolidation Test Results Plate C-3...CBR Test Results Copyright 2017 Christensen Geotechnical ii Spring Filling Station

5 1.0 EXECUTIVE SUMMARY This report presents the results of a geotechnical investigation conducted for the proposed Spring Filling Station to be located at approximately 625 North Main Street in Mantua, Utah and an assessment of 600 North Street and Main Street from 600 North to the north entrance of the Spring Filling Station in Mantua, Utah. The general location of the project is indicated on the Site Vicinity Map, Plate A-1 in Appendix A. In general, the purposes of this investigation were to evaluate the general subsurface conditions, the nature and engineering properties of the subsurface soils, and to provide recommendations for general site grading and for design and construction of foundations, pavement sections, and slabs-on-grade for the proposed building and to assess the existing pavement sections of 600 North and Main Street with the additional tanker truck traffic associated with the Spring Filling Station. Based on the subsurface conditions encountered at the site, it is our opinion that the subject site is suitable for the proposed construction provided that the recommendations contained in this report are complied with. The subsurface soil conditions were explored at the subject property by advancing four borings. One boring to a to depths of 16½ feet below the site grade at the location of the proposed Spring Filling Station building and three borings to depths of 6½ feet in Main Street and 600 North. Based on the four borings, the site of the proposed Spring Filling Station building is covered with approximately 2 feet of undocumented fill. Main Street and 600 North are covered with 4 to 8 inches of asphalt, 4 to 11 inches of untreated base, and 5 inches to over 5 feet of granular borrow or fill soils. Naïve soils below the asphalt and fill soils generally consisted of Lean CLAY (CL) to Fat CLAY (CH) through the depths explored. Groundwater was encountered at a depth of 7 feet in Boring B-1. The foundations for the proposed structure may consist of conventional strip and/or spread footings founded on undisturbed native soils. Strip and spread footings should be a minimum of 20 and 30 inches wide, respectively, and exterior shallow footings should be embedded at least 30-inches below final grade for frost protection and confinement. Conventional strip and spread footings founded on undisturbed, native soils may be proportioned for a maximum net allowable bearing capacity of 1,500 psf. Given the relatively heavy existing pavement section and that the existing pavement section is in good condition, it is our opinion that 600 North will support the additional tanker truck traffic in its current condition. Main Street shows significant signs of distress and likely has little service life left. It is our opinion that the existing Main Street pavement will not support the additional tanker truck traffic and should be reconstructed. Pavement sections for the Spring Filling Station access drives and Main Street are presented below is Section Recommendations for general site grading, design of foundations, slabs-on-grade, moisture protection as well as other aspects of construction are included in this report. NOTE: This executive summary is not intended to replace the report of which it is part and should not be used separately from the report. The executive summary omits a number of details, any one of which could be crucial to the proper application of this report. Copyright 2017 Christensen Geotechnical Spring Filling Station

6 2.0 INTRODUCTION 2.1 PURPOSE AND SCOPE OF WORK This report presents the results of a geotechnical investigation conducted for the proposed Spring Filling Station to be located at approximately 625 North Main Street in Mantua, Utah and an assessment of 600 North Street and Main Street from 600 North to the north entrance of the Spring Filling Station in Mantua, Utah. The general location of the project is indicated on the Site Vicinity Map, Plate A-1 in Appendix A. In general, the purposes of this investigation were to evaluate the general subsurface conditions, the nature and engineering properties of the subsurface soils, and to provide recommendations for general site grading and for design and construction of foundations, pavement sections, and slabs-on-grade for the proposed building and to assess the existing pavement sections of 600 North and Main Street with the additional tanker truck traffic associated with the Spring Filling Station. This investigation included subsurface exploration, representative soil sampling, field and laboratory testing, engineering analyses, and preparation of this report. The work performed for this report was authorized by Mayor Tyler Vincent and was conducted in accordance with our proposal dated April 24, PROJECT DESCRIPTION We understand that the proposed construction is to consist of a spring filling station building as well as asphalt access drives. The building is to be a single story steel structure with slab on grade floors at or near existing grades. The building is to be approximately 14 feet in height and have a 31 feet by 17 feet foot print. For design purposes it was assumed that structural loads would be on the order of 3 to 4 kips per lineal foot for walls and up to 80 kips for columns. Traffic for the Spring Filling Station is to consist of an average of 5 tanker trucks per day. The tanker trucks will consist of 6,000 gallon, 6,200 gallon, or 8,000 gallon trucks with total vehicle weights of approximately 78,200 lbs., 80,000 lbs., and 95,700 lbs., respectively. If structural loads or traffic loads are different than those assumed, we should be notified and allowed to reevaluate our recommendations. Copyright 2017 Christensen Geotechnical Spring Filling Station

7 3.0 METHOD OF STUDY 3.1 SUBSURFACE INVESTIGATION The subsurface conditions at the site were explored by drilling one borehole at the site of the Spring Filling Station building and three boreholes in 600 North and Main Street. The borehole at the building location was drilled to a depth of 16½ feet below existing site grade and the boreholes in the streets to depths of approximately 6½ feet below the top of the asphalt. The approximate locations of the explorations are shown on the Exploration Location Map, Plate A-2 in Appendix A. Logs of the subsurface conditions, as encountered in the boreholes, were recorded at the time of drilling and are presented on the Boring Logs, Plates B-1 to B-4. A Key to the soil symbols and terms used on the Boring Logs is found on Plate B-5. The boreholes were advanced with a Mobile B-80 truck mounted drill rig equipped with hollow stem augers. Disturbed soil samples were collected using standard split spoon and California samplers as well as through the collection of auger cuttings. Relatively undisturbed samples were collected with the use of Shelby tubes. Samples were visually classified in the field and portions of each sample were packaged and transported to our laboratory for testing. Classifications for the individual soil units are shown on the attached Boring Logs. 3.2 LABORATORY TESTING Representative samples were tested in the laboratory to evaluate the pertinent engineering properties of the samples obtained during our field investigation. Laboratory tests included natural moisture content and density determinations, gradation analyses, Atterberg limits determinations, a consolidation test, a proctor test, and a California bearing ratio test. A summary of our laboratory testing is presented in the table below: Table No. 1: Laboratory Test Results TEST HOLE NO. DEPTH (ft.) NATURAL MOISTURE (%) NATURAL DRY DENSITY (pcf) ATTERBERG LIMITS LL PI GRAIN SIZE DISTRIBUTION (%) GRAVE L (+ #4) SAND SILT/ CLAY (- #200) CBR **SOIL TYPE B CL B-2 1½ CL B CH **Detailed descriptions of the soils encountered are presented on the test pit logs Copyright 2017 Christensen Geotechnical Spring Filling Station

8 The results of laboratory tests are also presented on the Boring Logs in Appendix B (Plates B-1 to B-4) and more detailed laboratory results are presented in Appendix C (Plates C-1 to C-3). Samples with be retained in our laboratory for 30 days following the date of this report at which time they will be disposed of unless a written request for additional holding time is received prior to the disposal date. 3.3 ENGINEERING ANALYSIS Engineering analyses were performed using soil data obtained from the laboratory test results and empirical correlations from material density, depositional characteristics and classification. Appropriate factors of safety were applied to the results consistent with industry standards and the accepted standard of care. Copyright 2017 Christensen Geotechnical Spring Filling Station

9 4.0 GENERALIZED SITE CONDITIONS 4.1 SURFACE CONDITIONS At the time of our investigation, the site of the proposed Spring Filling Statin building was a gravel covered parking area for an existing building and is located near the toe of the Mantua Lake embankment. The area was nearly level with little vegetation. Main Street was a two lane road with no shoulder. This roadway was observed to be in poor condition with some rutting and what appears to be significant patching of pot holes. The second roadway assessed, 600 North, was a two lane road with a turn lane and shoulders and was observed to be raised a few to many feet above the surrounding area. This roadway was observed to be in relatively good condition with no signs of rutting. Longitudinal cracking was observed, but was not severe. No other significant cracking or other signs of distress were observed. 4.2 SUBSURFACE CONDITIONS The subsurface soil conditions were explored at the subject property by advancing four borings. One boring to a to depths of 16½ feet below the site grade at the location of the proposed Spring Filling Station building and three borings to depths of 6½ feet in Main Street and 600 North. Subsurface soil conditions were logged during our field investigation and are included on the Boring Logs in Appendix B (Plates B-1 to B-4). The soil and moisture conditions encountered during our investigation are discussed below Soils Based on the four borings completed for this investigation, the site of the proposed Spring Filling Station building is covered with approximately 2 feet of undocumented fill. Main Street and 600 North are covered with 4 to 8 inches of asphalt, 4 to 11 inches of untreated base, and 5 inches to over 5 feet of granular borrow or fill soils. Naïve soils below the asphalt and fill soils generally consisted of Lean CLAY (CL) to Fat CLAY (CH) through the depths explored. The stratification lines shown on the enclosed Boring Logs represent the approximate boundary between soil types. The actual in-situ transition may be gradual. Due to the nature and depositional characteristics of the native soils, care should be taken in interpolating subsurface conditions between and beyond the exploration locations. Copyright 2017 Christensen Geotechnical Spring Filling Station

10 4.2.2 Groundwater Conditions Groundwater was encountered boring B-1 at a depth of approximately 7 feet below existing site grade. Seasonal fluctuations in precipitation, surface runoff from adjacent properties, or other on or offsite sources may increase moisture conditions; groundwater conditions can be expected to rise several feet during wetter years and seasonally depending on the time of year. The contractor should anticipate implementing trench dewatering for any trenches or excavations greater than 7 feet in depth or possibly shallower. Copyright 2017 Christensen Geotechnical Spring Filling Station

11 5.0 GEOLOGIC CONDITIONS 5.1 SUFICIAL GEOLOGY The subject site is located in Mantua City, Utah, adjacent to Mantua Lake. Geologic mapping of this area indicates that the near surface geology of the subject site consists of Holocene to Pleistocene side-stream alluvium and fan deposits. These deposits are unconsolidated, crudely stratified, clay to boulder-size material deposited in tributary stream channels and alluvial fans; commonly includes terrace deposits, colluvium, talus, or lake deposits. Thickness is thought to be a few meters or less (Dover, 1995). 5.2 FAULTING Based upon published data, no active faults are known to traverse the site and no faulting was indicated during our field investigation. The nearest known active fault is the Brigham City Segment of the Wasatch Fault which lies approximately 2.3 miles west of the subject property (UGS). 5.3 SEISMIC DESIGN CRITERIA The State of Utah and Utah municipalities have adopted the 2015 International Building Code (IBC) for seismic design. The IBC seismic design is based on seismic hazard maps depicting probabilistic ground motions and spectral response which has been developed by United States Geological Survey (USGS) and the soil site class of the subject site. Seismic design values including the design spectral response may be calculated for a specific site using the USGS Seismic Design Maps web based application. Based on our field exploration, it is our opinion that this location is best described as a Site Class D which represents a stiff soil profile. The spectral accelerations are calculated based on this Site Class and the site s approximate latitude and longitude of and Based on the USGS web based application spectral acceleration values, the peak ground acceleration (PGA) is estimated to be 0.47g. The spectral accelerations are shown in the table below. Copyright 2017 Christensen Geotechnical Spring Filling Station

12 MCE R Seismic Response Spectrum Spectral Acceleration Values for IBC Site Class D a Spectral Period (sec) Site Location: Latitude = N Longitude = W Response Spectrum Spectral Acceleration (g) 0.2 S S =1.132g S MS =1.185g S DS =0.790g 1.0 S 1 = 0.389g S M1 =0.631g S D1 =0.421g 5.4 LIQUEFACTION Certain areas within the intermountain region possess a potential for liquefaction during seismic events. Liquefaction is a phenomenon whereby loose, saturated, granular soil deposits lose a significant portion of their shear strength due to excess pore water pressure buildup resulting from dynamic loading, such as that caused by an earthquake. Among other effects, liquefaction can result in densification of such deposits causing settlements of overlying layers after an earthquake as excess pore water pressures are dissipated. The primary factors affecting liquefaction potential of a soil deposit are: (1) level and duration of seismic ground motions; (2) soil type and consistency; and (3) depth to groundwater. No liquefaction potential map is available for the Mantua area; however, soils encountered through the depths explored have a low potential for liquefaction. It is possible that liquefiable layers exist below the depths explored. A full liquefaction analysis was beyond the scope of this report; however, if the owner wishes to have greater understanding of the liquefaction potential, a boring to a depth of at least 50 feet and additional analysis should be completed. Copyright 2017 Christensen Geotechnical Spring Filling Station

13 6.0 ENGINEERING ANALYSIS AND RECOMMENDATIONS 6.1 GENERAL CONCLUSIONS Based on the results of our field and laboratory investigations, it is our opinion that the subject site is suitable for the proposed construction provided that the recommendations contained in this report are incorporated into the design and construction of the project. In general, structures and pavements may be supported by conventional continuous or spread footings established on properly placed and compacted structural fill or undisturbed native soil. The existing pavement of 600 North is adequate to support the anticipated additional filling station traffic load. The existing pavement of Main Street appears to have little service life left and should be reconstructed to support the additional truck traffic. Specific recommendations regarding site grading, structural fill placement, and foundation design are presented in Sections 6.2 and 6.3 of this report. Additional sections of this report present our recommendations for concrete flatwork, pavement, and moisture protection. 6.2 EARTHWORK Prior to the placement of foundations, general site grading is recommended to provide proper support for foundations, exterior concrete flatwork, and concrete slabs-on-grade. Site grading is also recommended to provide proper drainage and moisture control on the subject property and to aid in preventing differential settlement of foundations as a result of variations in subgrade moisture conditions General Site Preparation and Grading Within areas to be graded (below proposed structures, fill sections, concrete flatwork, or pavement sections), any existing vegetation, debris, topsoil, undocumented fill, or otherwise unsuitable soils should be removed. Any soft, loose, or disturbed soils should also be removed. Following the removal of vegetation, unsuitable soils, and loose or disturbed soils, as described above, site grading may be conducted to bring the site to design elevations. Based on our observations in the borings drilled for the site investigation, there is approximately 2 feet of undocumented fill overlying the proposed Spring Filling Station building site. Main Street is covered with approximately 1½ feet asphalt, untreated base and fill soils. These Copyright 2017 Christensen Geotechnical Spring Filling Station

14 materials should be removed prior to placement of structural fill, structures, concrete flatwork and pavements. If over-excavation is required, the excavation should extend a minimum of one foot laterally for every foot of depth of over-excavation. Excavations should extend laterally at least two feet beyond flatwork, pavements, and slabs-on-grade. If materials are encountered that are not represented in the boring logs or may present a concern, we should be notified so observations and further recommendations as required can be made. A Christensen Geotechnical representative should observe the site preparation and grading operations to assess that the recommendations presented in this report are complied with Soft Soil Stabilization Soft or pumping soils may be exposed in excavations at the site. Once exposed, all subgrade surfaces beneath proposed structures, pavements, and flat work concrete should be proof rolled with a piece of heavy wheeled-construction equipment. If soft or pumping soils are encountered, these soils should be stabilized prior to construction of footings, pavements, and concrete flatwork. In smaller areas stabilization of the subgrade soils can be accomplished using a clean, coarse angular material worked into the soft subgrade. We recommend angular gravel with particles less than 6 inches in diameter but greater than 2 inch diameter. The stabilization material should be worked (pushed) into the soft subgrade soils until a firm relatively unyielding surface is established. Once a firm, relatively unyielding surface is achieved, the area may be brought to final design grade using structural fill. To address larger areas and/or more severe conditions, the subgrade may be stabilized with the use of a woven geotextile. In these areas a woven geotextile fabric should be placed over the soft soils which should then be covered by 18 inches of coarse, sub-rounded to rounded gravel fill which should be compacted until firm unyielding. An inexpensive non-woven geotextile filter fabric should also be placed over the top of the coarse, sub-rounded to rounded fill prior to placing any overlying structural fill or pavement section soils to reduce infiltration of fines from above. The woven geotextile should be Mirafi RS280i or prior approved equivalent. The filter fabric should consist of a Mirafi 140N, or equivalent as approved by the Geotechnical Engineer Excavation Stability Based on Occupational Safety and Health Administration (OSHA) guidelines for excavation safety, trenches with vertical walls up to 5 feet in depth may be occupied, however, the presence of fill soils, loose soils, or wet soils may require that the walls be flattened to maintain safe Copyright 2017 Christensen Geotechnical Spring Filling Station

15 working conditions. Based on our soil observations, laboratory testing, and OSHA guidelines, native soils at the site classify as Type C soils. Deeper excavations, if required, should be constructed with side slopes no steeper than one and one-half horizontal to one vertical (1.5H:1V). If wet conditions are encountered, side slopes should be further flattened to maintain slope stability. Alternatively shoring or trench boxes may be used to improve safe work conditions in trenches. Stability of construction excavations is the contractor s responsibility. If stability of an excavation becomes questionable, the excavation should be evaluated promptly by qualified personnel. Measures should be taken to protect construction personnel from falling rocks and raveling of trench sidewalls Structural Fill and Compaction All fill placed for the support of structures, concrete flatwork or pavements should consist of structural fill. Due to the high liquid limit of the native clay soils, we do not recommend that these soils be used as structural fill below the proposed building. The native clay soils may be used as structural fill below pavements; however, it should be understood that these soils will likely be difficult to moisture condition and compact. The existing untreated base and fill soils may be reworked and used as structural fill below the proposed building and pavements; however, care should be taken to remove any debris within this material and avoid contamination with the native clay soils. Topsoil should not be utilized as structural fill, but rather may be stockpiled for use in landscaped areas. Imported structural fill, if required, should consist of a relatively well graded granular soil with a maximum of 50 percent passing the No. 4 mesh sieve and a maximum fines content (minus No.200 mesh sieve) of 25 percent. Clay and silt particles in imported structural fill should have a liquid limit less than 35 and a plasticity index less than 15 based on the Atterberg Limit s test (ASTM D-4318). Regardless of whether the structural fill is imported or native, it should be free of vegetation, debris or frozen material, and should contain no inert materials larger than 4 inches nominal size. All structural fill soils should be approved by the Geotechnical Engineer prior to placement. The contractor should anticipate testing all soils used as structural fill frequently to assess the maximum dry density, fines content, and moisture content, etc. All structural fill should be placed in maximum 6-inch loose lifts if compacted by small handoperated compaction equipment, maximum 8-inch loose lifts if compacted by light-duty rollers, and maximum 10-inch loose lifts if compacted by heavy duty compaction equipment that is Copyright 2017 Christensen Geotechnical Spring Filling Station

16 capable of efficiently compacting the entire thickness of the lift. We recommend that all structural fill be compacted on a horizontal plane, unless otherwise approved by the geotechnical engineer. Structural fill below footings, pavements and flatwork concrete should be compacted to at least 95% of the maximum dry density, as determined by ASTM D The moisture content should be within 3 percent of the optimum moisture content at the time of placement and compaction. Also, prior to placing any fill, the excavations should be observed by the geotechnical engineer to observe that any unsuitable materials or loose soils have been removed. In addition, proper grading should precede placement of fill, as described in Section of this report. The gradation, placement, moisture, and compaction recommendations contained in this section may not meet the requirements of governing agencies such as city, county, or state entities. If their requirements exceed the recommendations presented here, their specifications should override those presented in this report. 6.3 FOUNDATIONS The foundation for the proposed building may consist of conventional strip and/or spread footings founded on undisturbed native soils. Strip and spread footings should be a minimum of 20 and 30 inches wide, respectively, and exterior shallow footings should be embedded at least 30-inches below final grade for frost protection and confinement. Interior footings not subject to frost should be embedded at least 18 inches below final grade to provide adequate confinement. Conventional strip and spread footings founded on undisturbed, native soils may be proportioned for a maximum net allowable bearing capacity of 1,500 psf. The net allowable bearing capacity may be increased (typically by one-third) for temporary loading conditions such as transient wind and seismic loads. All footing excavations should be observed by the Geotechnical Engineer prior to footing placement. 6.4 SETTLEMENT Settlements of properly designed and constructed conventional footings, founded as described above, are anticipated to be less than 1 inch. Differential settlements should be on the order of half the total settlement over 30 feet. Copyright 2017 Christensen Geotechnical Spring Filling Station

17 6.5 EARTH PRESSURES AND LATERAL RESISTANCE Buried structures, such as basement walls, should be designed to resist the lateral loads imposed by the soils retained. The lateral earth pressures on the below grade walls and the distribution of those pressures depends upon the type of structure, hydrostatic pressures, in-situ soils, backfill, and tolerable movements. Basement and retaining walls are usually designed with triangular stress distributions known as equivalent fluid pressure based on lateral earth pressure coefficients. If soils similar to the native soils are used to backfill basement walls then the walls may be designed using the following ultimate values: Condition Lateral Pressure Equivalent Fluid Density Coefficient (pounds per cubic foot) Active At-rest Passive Seismic Active Seismic Passive We recommend that walls which are allowed little or no wall movement be designed using at rest conditions. Walls allowed to rotate at least 0.4 percent of the wall height may be designed with active pressures. The coefficients and densities presented above assume level, granular backfill with no buildup of hydrostatic pressures. Hydrostatic and any surcharge loads should be added to the presented values if anticipated. If sloping backfill is present, we recommend the geotechnical engineer be consulted to provide more accurate lateral pressure parameters once the design geometry is established. For seismic analyses, the active and passive earth pressure coefficient provided in the table is based on the Mononobe-Okabe method and only accounts for the dynamic horizontal thrust produced by ground motion. Hence, the resulting dynamic thrust pressure should be added to the static pressure to determine the total pressure on the wall. The pressure distribution of the dynamic horizontal thrust may be closely approximated as an inverted triangle with stress decreasing with depth and the resultant acting at a distance approximately 0.6 times the loaded height of the structure, measured upward from the bottom of the structure. Lateral building loads will be resisted by frictional resistance between the footings and the foundations soils and by passive pressure developed by backfill against the wall. For footings on Copyright 2017 Christensen Geotechnical Spring Filling Station

18 native soils we recommend an ultimate coefficient of friction of 0.31 be used. If passive resistance is used in conjunction with frictional resistance, the passive resistance should be reduced by ½. Resisting passive earth pressure from soils subject to frost or heave, or otherwise above prescribed minimum depths of embedment, should usually be neglected in design. The coefficients and equivalent fluid densities presented above are ultimate values and should be used with an appropriate factor of safety against overturning and sliding. A value of 1.5 is typically used. 6.6 CONCRETE SLAB-ON-GRADE CONSTRUCTION Concrete slabs-on-grade should be constructed over at least 4 inches of compacted gravel to help distribute floor loads, break the rise of capillary water, and aid in the curing process. The gravel should consist of road base or clean drain rock with a ¾-inch maximum particle size and no more than 12 percent fines passing the No. 200 mesh sieve. The gravel layer should be compacted to at least 95 percent of the maximum dry density of modified proctor or until tight and relatively unyielding if the material is non-proctorable. All concrete slabs should be designed to minimize cracking as a result of shrinkage. Consideration should be given to reinforcing the slab with welded wire, re-bar, or fiber mesh. 6.7 MOISTURE PROTECTION AND SURFACE DRAINAGE Wetting of the foundation soils will likely cause some degree of volume change within the soil and should be prevented both during and after construction. We recommend that the following precautions be taken at this site: 1. The ground surface should be graded to drain away from the structures in all directions. We recommend a minimum fall of 8 inches in the first 10 feet. 2. Roof runoff should be collected in rain gutters with down spouts designed to discharge well outside of the backfill limits. 3. Sprinkler heads should be aimed away and kept at least 12 inches from foundation walls. 4. Provide adequate compaction of backfill around foundation walls with a minimum 90% density (ASTM D 1557). Water consolidation methods should not be used. 5. Other precautions which may become evident during design and construction should be taken. Copyright 2017 Christensen Geotechnical Spring Filling Station

19 6.8 PAVEMENT As part of our geotechnical investigation, Christensen Geotechnical has assessed the existing pavement sections of 600 North and Main Street from 600 North to the north entrance of the Spring Filling Station. In addition, pavement recommendations for the existing roadways and pavement within the facility are provided. A description of our assessment and recommendations as well as supporting information is presented in the following sections Traffic Based on information provided to Christensen Geotechnical, we understand that the Spring Filling Station traffic is to consist of an average of 5 tanker trucks per day. The tanker trucks will consist of 6,000 gallon, 6,200 gallon, or 8,000 gallon trucks with total weights on the order of 78,200 lbs., 80,000 lbs., and lbs. respectively. Existing vehicle traffic for 600 North and Main Street was assumed to consist of 500 passenger cars, 5 light trucks and 1 heavy truck per day. We have assumed that the traffic will be relatively consistent over the design life of the pavement sections. Therefore, no growth factor was applied in calculation of the traffic loads. The traffic as outlined above result in the following traffic loads for a 20 year design life. Traffic Condition With City Traffic ESAL s With No City Traffic ESAL s Existing City Traffic 50,500 NA 6,000 Gallon Tanker 131,300 81,900 6,200 Gallon Tanker 139,800 90,400 8,000 Gallon Tanker 233, , Existing Pavement Condition Based on our observations, 600 North is in relatively good condition with no signs of rutting. Longitudinal cracking was observed, but was not severe. No other significant cracking or other signs of distress were observed. Boring B-4 located in 600 North indicated a pavement section of 6 inches of asphalt over 11 inches of untreated base. Below the base, imported fill soils (granular borrow) consisting of Silty GRAVEL with sand (GM) was encountered through the maximum depth explored (6½ feet). The asphalt encountered in Boring B-4 was in good condition and the untreated base and underlying fill soils show little sign of contamination with fines from the underlying soils. Copyright 2017 Christensen Geotechnical Spring Filling Station

20 Main Street from 600 North to the north entrance to the Spring Filling Station was observed to be in poor condition with some rutting and what appears to be significant patching of pot holes. Borings B-2 and B-3 located in Main Street encountered 4 to 8 inches of Asphalt over 4 to 6 inches of untreated base overlying 5 inches of granular borrow (subbase). The asphalt encountered in Boring B-2 was in very poor condition, offering little resistance to drilling. Asphalt encountered in Boring B-3 was in fair condition. Untreated base and granular borrow encountered in Borings B-2 and B-3 showed significant infiltration with fines from the underlying clay soils and was in a relatively poor condition Pavement Sections Pavement design for the pavement section presented below were prepared using the PAS computer program by the American Concrete Pavement Association and a laboratory obtained CBR value of 3.7 which represents a poor pavement support. Traffic loads used in our analyses are those presented in Section Using the information presented above the following minimum pavement sections are recommended. Traffic Condition With City Traffic With No City Traffic Existing City Traffic 3 inches of Asphalt NA 12 inches of Untreated Base Or 3 inches of Asphalt 6 inches of Untreated Base 8 inches of Granular Borrow 6,000 Gallon Tanker Truck 3 inches of Asphalt 16 inches of Untreated Base Or 3 inches of Asphalt 8 inches of Untreated Base 10 inches of Granular Borrow 3 inches of Asphalt 14 inches of Untreated Base Or 3 inches of Asphalt 8 inches of Untreated Base 7 inches of Granular Borrow 6,200 Gallon Tanker Truck 3 inches of Asphalt 16 inches of Untreated Base Or 3 inches of Asphalt 8 inches of Untreated Base 10 inches of Granular Borrow 8,000 Gallon Tanker Truck 3.5 inches of Asphalt 17 inches of Untreated Base Or 3.5 inches of Asphalt 8 inches of Untreated Base 11 inches of Granular Borrow 3 inches of Asphalt 14 inches of Untreated Base Or 3 inches of Asphalt 8 inches of Untreated Base 7 inches of Granular Borrow 3.5 inches of Asphalt 15 inches of Untreated Base Or 3.5 inches of Asphalt 8 inches of Untreated Base 9 inches of Granular Borrow Copyright 2017 Christensen Geotechnical Spring Filling Station

21 Asphalt has been assumed to be a high stability plant mix. Base course material should be composed of crushed stone with a minimum CBR of 70. Granular borrow should meet the recommendations for imported structural fill presented in Section of this report. Asphalt should be compacted to a minimum density of 96% of the Marshall value and base course should be compacted to at least 95% of the maximum dry density of the modified proctor (ASTM D- 1557). Untreated base course material should meet the gradation and Atterberg Limits requirements of UDOT or Mantua City Pavement Conclusions The existing pavement section of 600 North as encountered in our field exploration consisted of 6 inches of asphalt, 11 inches of untreated base and over 5 feet of granular borrow. As indicated in Section 6.8.3, our recommended pavement section for the estimated city traffic with the additional five tanker trucks is significantly less that the existing pavement section. Given this and the good condition of the existing pavement section, it is our opinion that 600 North will support the additional tanker truck traffic in its current condition. As indicated in Section 6.8.2, the existing asphalt pavement of Main Street shows significant signs of distress and likely has little service life left. It is our opinion that the existing Main Street pavement will not support the additional tanker truck traffic. Due to the condition of the existing asphalt and untreated base, we do not recommend an overlay. We recommend reconstruction of Main Street with the pavement sections as recommended above. Copyright 2017 Christensen Geotechnical Spring Filling Station

22 7.0 CLOSURE 7.1 LIMITATIONS The recommendations contained in this report are based on our limited field exploration, laboratory testing, and understanding of the proposed construction. The subsurface data used in the preparation of this report were obtained from the explorations made for this investigation. It is possible that variations in the soil and groundwater conditions could exist between and beyond the points explored. The nature and extent of variations may not be evident until construction occurs. If any conditions are encountered at this site that are different from those described in this report, Christensen Geotechnical should be immediately notified so that we may make any necessary revisions to recommendations contained in this report. In addition, if the scope of the proposed construction changes from that described in this report, Christensen Geotechnical should be notified. This report was prepared in accordance with the generally accepted standard of practice at the time the report was written. No other warranty, expressed or implied, is made. It is the Client's responsibility to see that all parties to the project including the Designer, Contractor, Subcontractors, etc. are made aware of this report in its entirety. The use of information contained in this report for bidding purposes should be done at the Contractor's option and risk. 7.2 ADDITIONAL SERVICES The recommendations made in this report are based on the assumption that an adequate program of tests and observations will be made during construction. These tests and observations should include, but not necessarily be limited to, the following: Observations and testing during site preparation, earthwork and structural fill placement. Observation of foundation soils to assess their suitability for footing placement. Observation of soft/loose soils over-excavation. Consultation as may be required during construction. Quality control and observation of concrete placement. Copyright 2017 Christensen Geotechnical Spring Filling Station

23 We also recommend that project plans and specifications be reviewed by us to verify compatibility with our conclusions and recommendations. Additional information concerning the scope and cost of these services can be obtained from our office. Copyright 2017 Christensen Geotechnical Spring Filling Station

24 8.0 REFERENCES CITED Dover, J. H., 1995, Geologic Map of the Logan 30 X60 Quadrangle, Cache an Rich Counties Utah, and Lincoln and Uinta Counties, Wyoming, U.S. Geological Survey, Miscellaneous Investigation Series. Map I-2210, Scale 1:100,000. UGS, Utah Quaternary Fault and Fold Database, Interactive web based map. Copyright 2017 Christensen Geotechnical Spring Filling Station

25 HWY 91 Main Street Approximate Site Location 600 North Mantua Reservoir Center Street Base Photo: Utah AGRC Brigham City Corporation Spring Filling Station Mantua, Utah Project No Site Vicinity Map Plate A-1

26 B-2 B-1 B-4 B-3 Approximate Boring Location Drawing Not to Scale Brigham City Corporation Spring Filling Station Mantua, Utah Project No Exploration Location Map Plate A-2

27 Depth (feet) Sample Type Blow Counts (blows/foot) Groundwater Graphic Log Group Symbol Dry Density (pcf) Moisture Content (%) Minus #200 (%) Liquid Limit Plastic Limit Date Started: 5/11/2017 Logged By: M Christensen Boring No. Completed: 5/11/2017 BORING LOG Equipment: Mobile B-80 Backfilled: 5/11/2017 Location: See Plate A-2 B-1 Sheet 1 of 1 Material Description Fill; Silty GRAVEL with sand - brown, moist 14 Lean CLAY - stiff, moist, brown wet below 7 feet 17 CL Bottom of boring at 16½ feet 20 SPT Sampler Shelby Tube StabIlized Ground water California Sampler Bulk/Bag Sample Groundwater At time of Drilling Brigham City Corporation Spring Filling Station Mantua, Utah Project No.: Plate B-1

28 Depth (feet) Sample Type Blow Counts (blows/foot) Groundwater Graphic Log Group Symbol Dry Density (pcf) Moisture Content (%) Minus #200 (%) Liquid Limit Plastic Limit Date Started: 5/11/2017 Logged By: M Christensen Boring No. Completed: 5/11/2017 BORING LOG Equipment: Mobile B-80 Backfilled: 5/11/2017 Location: See Plate A-2 B-2 Sheet 1 of 1 Material Description Asphalt - 8 inches Road Base - 4 inches Granular Borrow - 5 inches Lean CLAY - stiff, moist, brown CL gray-green below 5 feet Bottom of boring at 6 ½ feet SPT Sampler Shelby Tube StabIlized Ground water California Sampler Bulk/Bag Sample Groundwater At time of Drilling Brigham City Corporation Spring Filling Station Mantua, Utah Project No.: Plate B-2

29 Depth (feet) Sample Type Blow Counts (blows/foot) Groundwater Graphic Log Group Symbol Dry Density (pcf) Moisture Content (%) Minus #200 (%) Liquid Limit Plastic Limit Date Started: 5/11/2017 Logged By: M Christensen Boring No. Completed: 5/11/2017 BORING LOG Equipment: Mobile B-80 Backfilled: 5/11/2017 Location: See Plate A-2 B-3 Sheet 1 of 1 Material Description Asphalt - 4 inches Road Base - 6 inches Granular Borrow - 5 inches Fat CLAY - stiff, moist, brown CH Bottom of boring at 6 ½ feet SPT Sampler Shelby Tube StabIlized Ground water California Sampler Bulk/Bag Sample Groundwater At time of Drilling Brigham City Corporation Spring Filling Station Mantua, Utah Project No.: Plate B-3

30 Depth (feet) Sample Type Blow Counts (blows/foot) Groundwater Graphic Log Group Symbol Dry Density (pcf) Moisture Content (%) Minus #200 (%) Liquid Limit Plastic Limit Date Started: 5/11/2017 Logged By: M Christensen Boring No. Completed: 5/11/2017 BORING LOG Equipment: Mobile B-80 Backfilled: 5/11/2017 Location: See Plate A-2 B-4 Sheet 1 of 1 Material Description Asphalt - 6 inches Road Base - 11 inches Fill; Silty GRAVEL with sand - moist, brown Bottom of boring at 6 ½ feet SPT Sampler Shelby Tube StabIlized Ground water California Sampler Bulk/Bag Sample Groundwater At time of Drilling Brigham City Corporation Spring Filling Station Mantua, Utah Project No.: Plate B-4

31 Soil Symbols Description Key Plate B-5

32 Plasticity Index (%) Liquid Limit (%) Location Depth B-1 5 ft B-2 1 ½ ft B-3 5 ft Classification Liquid Limit PI Brigham City Corporation Spring Filling Station Mantua, Utah Project No.: Plate C-1

33 Brigham City Corporation Spring Filling Station Mantua, Utah Project No Plate C-2

34 Brigham City Corporation Spring Filling Station Mantua, Utah Project No Plate C-3