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Home My WebLink About20090057 • GEOTECHNICAL ENGINEERING REPORT PROPOSED PUMP HOUSE AND SEPARATOR FACILITY SOUTHWEST OF WELD COUNTY ROAD 32 AND WELD COUNTY ROAD 37 WELD COUNTY, COLORADO Terracon Project No. 21085021 August 18, 2008 • Prepared for: HIGH PLAINS DISPOSAL, INC. 601 S. MAIN STREET-SUITE 215 GRAPEVINE, TEXAS 76051 Attn: MR. ANDY CUNNINGHAM Prepared by: Terracon Consultants, Inc. 1289 1ST Avenue Greeley, Colorado 80631 Phone: 970-351-0460 Fax: 970-353-8639 • 2009-0057 lierracon lierracon n August 18, 2008 Consulting Engineers and Scientists 12891"Avenue • Greeley,Colorado 80631 Phone High Plains Disposal, Inc. Fax(970)353-8639 601 South Main Street—Suite 215 www.terracon.com Grapevine, Texas 79051 Attn: Mr. Andy Cunningham Re: Geotechnical Engineering Report Proposed Pump House and Separator Facility Southwest of Weld County Road 32 and Weld County Road 37 Weld County, Colorado Terracon Project No. 21085021 Terracon has completed geotechnical engineering exploration for the proposed Pump House and Separator Facility to be located Southwest of Weld County Road 32 and Weld County Road 37 in Weld County, Colorado. This study was performed in general accordance with our proposal number P2108027g dated June 3, 2008. The results of our engineering study are attached. These results include the Boring Location Diagram, laboratory test results, Logs of Boring, and the geotechnical recommendations needed • to aid in the design and construction of foundations and other earth connected phases of this project. We appreciate being of service to you in the geotechnical engineering phase of this project, and are prepared to assist you during the construction phases as well. Please do not hesitate to contact us if you have any questions concerning this report or any of our testin , inspection, design and consulting services. 0l0 Lice , O �pLD�,• � Sincerely, Tot TERRACON CONSULTANTS, INC. :1$QOZp$ T _ tea, .� "' 17- S/CNA1.0l Jason Mapes, E.I. Raymond L. Denton II, P.E. Staff Engineer Geotechnical Department Manager Reviewed by: Ed Paas, P.E. Geotechnical Engineer Copies to: Addressee (5) • Delivering Success for Clients and Employees Since 1965 More than 80 Offices Nationwide TABLE OF CONTENTS • Page No. Letter of Transmittal INTRODUCTION 1 SITE EXPLORATION 2 Field Exploration 2 Laboratory Testing 2 SITE CONDITIONS 3 Soil and Bedrock Conditions 3 Field and Laboratory Test Results 3 Groundwater Conditions 4 ENGINEERING RECOMENDATIONS 4 Geotechnical Considerations 4 Separator Tanks Foundation 4 In Ground Concrete Wash Pit Foundation Foundation 5 Modular Office Building Foundation 5 Roadway Design and Construction 6 Pavement Design and Construction 7 Compliance 9 Pavement Performance 9 • Lateral Earth Pressures 10 Seismic Considerations 10 Floor Slab Design and Construction 10 Septic System Construction 11 Earthwork 12 General Considerations 12 Site Preparation 12 Subgrade Preparation 13 Fill Materials and Placement 13 Excavation and Trench Construction 14 Additional Design and Construction Considerations 15 Exterior Slab Design and Construction 15 Underground Utility Systems 15 Corrosion Protection 15 Surface Drainage 15 GENERAL COMMENTS 16 • TABLE OF CONTENTS (cont.) ii BORING LOCATION DIAGRAM Figure No. 1 • APPENDIX A: LOGS OF BORING APPENDIX B: LABORATORY TEST RESULTS APPENDIX C; GENERAL NOTES • • ii GEOTECHNICAL ENGINEERING REPORT • PROPOSED PUMP HOUSE AND SEPARATOR FACILITY SOUTHWEST OF WELD COUNTY ROAD 32 AND WELD COUNTY ROAD 37 WELD COUNTY, COLORADO Terracon Project No. 21085021 August 18, 2008 INTRODUCTION This report contains the results of our geotechnical engineering exploration for the proposed project to be located Southwest of Weld County Road 32 and Weld County Road 37 in Weld County, Colorado. The purpose of these services is to provide information and geotechnical engineering recommendations relative to: • subsurface soil and bedrock conditions; • groundwater conditions; • foundation design and construction; • • lateral earth pressures; • floor slab design and construction; • roadway design and construction; • septic systems; • earthwork; and, • drainage. The recommendations contained in this report are based upon the results of field and laboratory testing, engineering analyses, our experience with similar soil conditions and structures, and our understanding of the proposed project. PROJECT INFORMATION Terracon understands the site will be developed with a pump house and 10 to 12 separator tanks. Additional infrastructure on the site will consist of a modular office building, gravel access roads, and a septic system. We understand that the separator tanks will be approximately 10 to 15 feet in diameter with a 30,000 gallon total tank capacity. For the purposes of this report, we assume that the separator tanks will be situated on one mat foundation. Future site development may consist of paving the proposed access road with asphalt concrete. • 1 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 Final site grading plans were not available prior to preparation of this report. However, we • assume cuts or fills will be on the order of 3 feet or less. SITE EXPLORATION PROCEDURES The scope of the services performed for this project included site reconnaissance by an engineering geologist, a subsurface exploration program, laboratory testing and engineering analysis. • Field Exploration: A total of 13 test borings were drilled on August 4, 2008 to depths of about 3 to 30 feet below existing site grade at the approximate locations shown on the Boring Location Diagram, Figure 1. Three borings were drilled within or near the footprint of the proposed separator tank mat foundation, one boring was drilled within or near the footprint of the pump house, one boring was drilled within or near the footprint of the proposed modular office building, and one boring was drilled in the area of proposed gravel access road. One soil profile boring and 6 percolation test holes were drilled in the location of the proposed septic system. Percolation tests were conducted in accordance with Weld County requirements. All borings were advanced with a truck-mounted drilling rig, utilizing 4-inch diameter, solid-stem, continuous-flight auger. The borings were located in the field by utilizing a hand-held Global Positioning System (GPS). • Elevations of each boring location were obtained from a topographical site plan provided to us by Lamp Rynearson & Associates, Inc. The accuracy of boring locations and elevations should only be assumed to the level implied by the methods used. Lithologic logs of each boring were recorded by the geotechnical engineer during the drilling operations. At selected intervals, samples of the subsurface materials were taken by driving split-spoon and ring barrel samplers. Penetration resistance measurements were obtained by driving the split-spoon and ring barrel samplers into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration resistance value is a useful index to the consistency, relative density or hardness of the materials encountered. Groundwater measurements were made in each boring at the time of site exploration, and one day after drilling. Laboratory Testing: Samples retrieved during the field exploration were returned to the laboratory for observation by the project geotechnical engineer, and were classified in general accordance with the Unified Soil Classification System described in Appendix C. Samples of bedrock were classified in accordance with the general notes for Rock Classification. At that time, an applicable laboratory-testing program was formulated to determine engineering • 2 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 • properties of the subsurface materials. Following the completion of the laboratory testing, the field descriptions were confirmed or modified as necessary, and Logs of Borings were prepared. These logs are presented in Appendix A. Laboratory test results are presented in Appendix B. These results were used for the geotechnical engineering analyses and the development of foundation and earthwork recommendations. Laboratory tests were performed in general accordance with the applicable local or other accepted standards. Selected soil and bedrock samples were tested for the following engineering properties: • Water content • Grain size • Dry density • Plasticity Index • Consolidation • Water soluble sulfate content • Expansion SITE CONDITIONS At the time of drilling operations the site consisted of open pasture land. The site was bounded on the north by Weld County Road 32, on the west by an access road, on the south by • open land, and on the east by Weld County Road 37. Vegetation consisted of a native grass and weed growth with a few mature cottonwood trees. Surface drainage consisted of surface sheet flow directed to the east. Soil and Bedrock Conditions: As presented on the Logs of Borings, approximately 6 inches of topsoil was encountered at the ground surface. Soils underlying the topsoil to depths of about 13 to 14.5 feet below existing site grade consisted of silty sand and clayey sand. The materials underlying the overburden materials and extending down to the full depth of exploration consisted of claystone bedrock. Field and Laboratory Test Results: Field test results indicate that the sand soils vary from loose to very dense in relative density. The claystone bedrock was weathered to medium hard in hardness. Laboratory test results indicate that subsoils at shallow depth have non- to low expansive potential. Laboratory tests indicate a negligible water soluble sulfate content of 39.7 ppm. • 3 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 Percolation testing conducted in the area of the proposed soil absorption bed is summarized as • follows: Test Depth Sfio Percolation Rate(minutes/inch) 1-toie -(inches} Classrftcation P-1 36 SM 5 P-2 36 SM 17 P-3 36 SM 13 P-4 36 SM 8 P-5 36 SM 22 P-6 36 SM 12 Field test results indicate the soils in the area of the proposed septic system have good percolation characteristics. Groundwater Conditions: Groundwater was encountered in test boring B-5 at a depth of about 13 feet below existing site grade in the test borings at the time of field exploration. When checked one day after drilling, groundwater was measured at a depth of 12 feet below existing site grade. Water was not encountered in the remaining test borings during or after drilling operations. These observations represent groundwater conditions at the time of the field exploration, and may not be indicative of other times or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions. • ENGINEERING RECOMMENDATIONS Geotechnical Considerations: Based on the results of our field investigation, laboratory testing program and geotechnical analyses, development of the site is considered feasible from a geotechnical standpoint provided that the conclusions and recommendations provided herein are incorporated into the design and construction of the project. Design and construction recommendations for foundation systems and other earth connected phases of the project are outlined below. Separator Tanks Foundation: A mat foundation bearing on suitable undisturbed subsoils is suitable for support of the proposed separator tanks and pumps. The foundation may be designed for a maximum allowable bearing pressure of 2,000 pounds per square foot (psf). We understand the tanks will be supported on a single mat. If this is incorrect we should be contacted to modify our recommendations. Total movement resulting from the assumed structural loads is estimated to be on the order of 1 to 2 inches. Additional foundation movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage practices should be incorporated into the design and operation of the facility. Failure to maintain soil water content will nullify the movement estimates provided above. • 4 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 lIP For structural design of mat foundations, a modulus of subgrade reaction of 25 pounds per cubic inch (pci) may be used. Other details including treatment of loose foundation soils and observation of foundation excavations are applicable for the design and construction of the foundation at the site and are outlined below. Exterior foundations should be placed a minimum of 30 inches below finished grade for frost protection and to provide confinement for the bearing soils. Finished grade is the lowest adjacent grade for perimeter footings. Below Grade Concrete Wash Pit Foundation: Due to the presence of non- to low swelling soils on the site, spread footing foundation systems bearing upon suitable undisturbed subsoils, recompacted native soils and/or engineered fill are recommended for support of the proposed below grade concrete wash pit. The footings may be designed for a maximum bearing pressure of 2,000 pounds per square foot (psf). The design bearing pressure applies to dead loads plus design live load conditions. The design bearing pressure may be increased by 1/3 when considering total loads that include wind or seismic conditions. Footings should be proportioned to relative constant dead load pressure in order to reduce differential movement between adjacent footings. Total movement resulting from the assumed structural loads is estimated to be on the order of about 1 inch. Additional foundation • movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage should be provided in the final design and during construction. Foundations should be placed a minimum of 30 inches below finished grade for frost protection and to provide confinement for the bearing soils. Finished grade is the lowest adjacent grade for perimeter footings. Footings, foundations and masonry walls should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities in masonry walls is recommended. Foundation excavations or new fill placement operations should be observed by the geotechnical engineer. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. Modular Office Building Foundation: Due to the presence of non- to low swelling soils on the site, spread footing foundation systems bearing upon undisturbed subsoils, recompacted native soils and/or engineered fill are recommended for support of the proposed modular office building. The footings may be designed for a maximum bearing pressure of 2,000 pounds per square foot (psf). The design bearing pressure applies to dead loads plus design live load conditions. The design bearing pressure may be increased by 1/3 when considering total loads • that include wind or seismic conditions. 5 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 Footings should be proportioned to relative constant dead load pressure in order to reduce • differential movement between adjacent footings. Total movement resulting from the assumed structural loads is estimated to be on the order of about 1 inch. Additional foundation movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage should be provided in the final design and during construction. Foundations should be placed a minimum of 30 inches below finished grade for frost protection and to provide confinement for the bearing soils. Finished grade is the lowest adjacent grade for perimeter footings. Footings, foundations and masonry walls should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities in masonry walls is recommended. Foundation excavations or new fill placement operations should be observed by the geotechnical engineer. If the soil or fill conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. Roadway Design and Construction: Design of the gravel access roads for the project has been based on the procedures outlined in the 1993 Guide for Design of Pavement Structures by the American Association of State Highway and Transportation Officials (AASHTO). • Based upon AASHTO criteria, Colorado is located within Climatic Region VI of the United States. This region is characterized as being dry, with hard ground freeze and spring thaw. The spring thaw condition typically results in saturated or near-saturated subgrade soil moisture conditions. The AASHTO criteria suggest that these moisture conditions are prevalent for approximately 12-1/2 percent of the annual moisture variation cycle. Local drainage characteristics of proposed pavement areas are considered to vary from fair to good depending upon location on the site. For purposes of this design analysis, fair drainage characteristics are considered to control the design. These characteristics, coupled with the approximate duration of saturated subgrade conditions, result in a design drainage coefficient of 1.0 when applying the AASHTO criteria for design. For gravel access road design, a modulus of aggregate base layer of 30,000 psi was utilized along with an allowable depth of rutting of 2.5 inches. The Equivalent Daily 18 kip Load Application (EDLA) for the project was assumed to be 50. Based on the subsurface conditions encountered at the site, and the laboratory test results, it is recommended that the access road areas be designed using a minimum R-value of 15. Based on Figure 4.3, Design Chart for Aggregate-Surfaced Roads Considering Allowable Rutting, 1993 Guide for Design of Pavement Structures by the American Association of State Highway and Transportation Officials (AASHTO), the recommended thickness of the roadbase section was determined to be 9 • Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 • inches. Terracon should be notified if any of the assumptions made for the roadway design are not correct. We recommend the roadway areas be rough graded and then thoroughly proofrolled with a loaded tandem axle dump truck prior to final grading. Particular attention should be paid to areas where backfilled trenches are located. Areas where unsuitable conditions are located should be repaired by removing and replacing the materials with properly compacted fills. Roadway areas should be moisture conditioned and properly compacted to the recommendations in this report immediately prior to paving. Aggregate base course (if used on the site) should consist of a blend of sand and gravel which meets strict specifications for quality and gradation. Use of materials meeting Colorado Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for base course. Aggregate base course should be placed in lifts not exceeding 6 inches and compacted to a minimum of 95 percent standard Proctor density (ASTM D698). Pavement Design and Construction: Design of pavement thickness, for future placement on the proposed gravel access road, has been based on the procedures outlined in the 1993 • Guideline for Design of Pavement Structures by the American Association of State Highway and Transportation Officials (AASHTO). The design presented herein is for planning purposes for the project. Terracon should re-evaluate the roadway subgrade and base course prior to paving. For the purposes of providing pavement sections we have assumed traffic loading of 50, 18-kip equivalent daily load applications (EDLA's) for the project. Terracon should be notified if any of the assumptions made for the pavement design are not correct. Based upon AASHTO criteria, Colorado is located within Climatic Region VI of the United States. This region is characterized as being dry, with hard ground freeze and spring thaw. The spring thaw condition typically results in saturated or near-saturated subgrade soil moisture conditions. The AASHTO criteria suggest that these moisture conditions are prevalent for approximately 12-1/2 percent of the annual moisture variation cycle. Local drainage characteristics of proposed pavement areas are considered to vary from fair to good depending upon location on the site. For purposes of this preliminary design analysis, fair drainage characteristics are considered to control the design. These characteristics, coupled with the approximate duration of saturated subgrade conditions, result in a design drainage coefficient of 1.0 when applying the AASHTO criteria for design. • 7 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 For flexible pavement design, a terminal serviceability index of 2.0 was utilized along with an • inherent reliability of 80% and a design life of 20 years. Using a correlated design R-value of 15, appropriate ESAL, environmental criteria and other factors, the structural numbers (SN) of the pavement sections were determined on the basis of the 1993 AASHTO design equation. Recommendations for flexible pavements, are as follows: • Preliminary Pavement Thttkttr}ss(ufcties) '.6- 4f.'; Traffic AreaAggre gatePortland' Co tcreteaissowvCement vol!LEinPr !1O.7r4tAlkit Industrial Commercial A 5 8 --- 13 EDLA= 50 Before paving the gravel access road, a supplemental geotechnical exploration should be performed to confirm or modify the pavement thickness recommendations presented in this report. Accordingly, the actual thickness may vary from those outlined above. We recommend the pavement areas be thoroughly proofrolled with a loaded tandem axle dump truck prior to final grading. Areas where unsuitable conditions are located should be repaired by • removing and replacing the materials with properly compacted fills. Pavement areas should be moisture conditioned and properly compacted to the recommendations in this report immediately prior to paving. The placement of a partial pavement thickness for use during construction is not suggested without a detailed pavement analysis incorporating construction traffic. In addition, we should be contacted to confirm the traffic assumptions outlined above. If the actual traffic varies from the assumptions outlined above, modification of the pavement section thickness will be required. Asphalt concrete should be composed of a mixture of aggregate, filler and additives (if required) and approved bituminous material. The asphalt concrete should conform to approved mix designs stating the superpave volumetric properties, optimum asphalt content, job mix formula and recommended mixing and placing temperatures. Aggregate used in asphalt concrete should meet particular gradations. Material meeting CDOT Grading S, SG, or SX specifications or equivalent is recommended for asphalt concrete. Mix designs should be submitted prior to construction to verify their adequacy. Asphalt material should be placed in maximum lifts of 2, 3.5, and 5-inches for grading SX, S, and SG; respectively, and compacted within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM D2041). The asphalt binder grading should be selected based upon the local government entity input. • 8 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 • Compliance: Recommendations for pavement construction presented depend upon compliance with recommended material specifications. To assess compliance, observation and testing should be performed under the direction of the geotechnical engineer. Pavement Performance: Pavement design methods are intended to provide structural sections with adequate thickness over a particular subgrade such that wheel loads are reduced to a level the subgrade can support. The support characteristics of the subgrade for pavement design do not account for shrink/swell movements of a clay subgrade such as the soils encountered on this project. Thus, the pavement may be adequate from a structural standpoint, yet still experience cracking and deformation due to shrink/swell relate movement of the subgrade. It is, therefore, important to minimize moisture changes in the subgrade to reduce shrink/swell movements. Future performance of pavements constructed on the clay soils at this site will be dependent upon several factors, including: • maintaining stable moisture content of the subgrade soils. • providing for a planned program of preventative maintenance. The performance of pavements can be enhanced by minimizing excess moisture which can • reach the subgrade soils. The following recommendations should be considered at minimum: • site grading at a minimum 2 percent grade away from the pavements. • the subgrade and the pavement surface have a minimum 1/4 inch per foot slope to promote proper surface drainage. • consider appropriate edge drainage and pavement underdrain systems. • install pavement drainage surrounding areas anticipated for frequent wetting (e.g., garden centers, wash racks). • install joint sealant and seal cracks immediately. • compaction of any utility trenches for landscaped areas to the same criteria as the pavement subgrade. Preventative maintenance on the proposed gravel access road and paved access road should be planned and provided for through an ongoing management program to enhance future roadway performance. Preventative maintenance activities are intended to slow the rate of deterioration and to preserve the roadway investment. Preventative maintenance for the gravel access road will consist of periodic grading. After the gravel access road is paved, both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing) will be required. Preventive maintenance is usually the first priority when implementing a planned roadway maintenance • program and provides the highest return on the investment. 9 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 Lateral Earth Pressures: For soils above any free water surface, recommended equivalent • fluid pressures for unrestrained foundation elements are: • Active: Cohesionless soil backfill (sands) 35 psf/ft • Passive: Cohesionless soil backfill (sands) 350 psf/ft • Coefficient of base friction 0.35* *The coefficient of base friction should be reduced to 0.30 when used in conjunction with passive pressure. Where the design includes restrained elements such as pit walls, the following equivalent fluid pressures are recommended: • At rest: Cohesionless soil backfill (sands) 55 psf/ft The lateral earth pressures herein do not include any factor of safety and are not applicable for • submerged soils/hydrostatic loading. Additional recommendations may be necessary if submerged conditions are to be included in the design. Fill against foundations should be compacted to densities specified in the "Earthwork" section of this report. Compaction of each lift adjacent to walls should be accomplished with hand- operated tampers or other lightweight compactors. Overcompaction may cause excessive lateral earth pressures which could result in wall movement. Seismic Considerations: A site classification "C" should be used for the design of structures for the proposed project (2006 International Building Code, Table No. 1613.5.2). Floor Slab Design and Construction: Slab-on-grade construction for interior floor systems is generally considered acceptable when bearing on non- to low expansive materials, provided that some movement can be tolerated. Movement on the order of about one inch is possible. Use of structural floor systems, structurally supported independent of the subgrade soils, is a positive means of reducing the potentially detrimental effects of floor movement. For structural design of concrete slabs-on-grade, a modulus of subgrade reaction of 150 pounds per cubic inch (pci) may be used for floors supported on existing sand soils or non-expansive, imported fill meeting the specifications outlined below. • 10 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 • Additional floor slab design and construction recommendations are as follows: • Positive separations and/or isolation joints should be provided between slabs and all foundations, columns or utility lines to allow independent movement. • Control joints should be provided in slabs to control the location and extent of cracking. • Interior trench backfill placed beneath slabs should be compacted in accordance with recommended specifications outlined below. • The use of vapor retarder should be considered beneath concrete slabs-on-grade that will be covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 for procedures and cautions regarding the use and placement or a vapor retarder. • Floor slabs should not be constructed on frozen subgrade. • • Other design and construction considerations, as outlined in Section 302.1R of the ACI Design Manual, are recommended. Septic System Construction: Field test results indicate that a standard septic system and leach field (soil absorption bed) is feasible for construction on the site at the location of percolation test holes 1 through 6. The system should be designed in accordance with Weld County Individual Sewage Disposal System Regulations dated August 15, 2005. An average percolation rate of 13 minutes per inch is recommended for design purposes. Additional design criteria for septic system construction are as follows: • Based upon the proposed structure, the proposed soil absorption bed should include a minimum of 400 square feet of bed absorption area. • A minimum 1000-gallon capacity septic tank should be used in the design and construction. • Distribution lines within the soil absorption bed should consist of 4-inch diameter perforated plastic or similar pipe approved in governing regulations. • 11 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 • Distribution lines should be placed the full length of the proposed absorption bed or • trench and should not exceed 100 feet in length. Distribution lines should be spaced at a maximum of 6 feet on-center with the perimeter lines placed within 3 feet of all sides in the absorption bed. • Absorption beds should be backfilled with a minimum 12-inch thickness of clean graded gravel ranging in size from 1/2 to 2-1/2 inches in diameter. The gravel should extend a minimum of 6 inches below and 2 inches above the distribution pipes. • The gravel bed should be completely covered with untreated building paper prior to final soil cover. Final soil cover should be a minimum of 12 inches in thickness and suitable for vegetative growth. The surface of the soil cover should be graded for positive surface drainage and to reduce the possibility of surface water infiltration. Earthwork: General Considerations: The following presents recommendations for site preparation, excavation, subgrade preparation and placement of engineered fills on the project. All earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of engineered fills, subgrade . preparation, foundation bearing soils and other geotechnical conditions exposed during the construction of the project. Site Preparation: Strip and remove existing vegetation, and other deleterious materials from proposed building and pavement areas. All exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. Stripped materials consisting of vegetation and organic materials should be wasted from the site or used to revegetate landscaped areas or exposed slopes after completion of grading operations. If it is necessary to dispose of organic materials on-site, they should be placed in non-structural areas and in fill sections not exceeding 5 feet in height. The site should be initially graded to create a relatively level surface to receive fill and to provide for a relatively uniform thickness of fill beneath proposed structures. All exposed areas which will receive fill, once properly cleared and benched, should be scarified to a minimum depth of 12 inches, conditioned to near optimum moisture content and compacted. Although evidence of fills or underground facilities such as septic tanks, cesspools, basements and utilities was not observed during the site reconnaissance, such features • 12 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 could be encountered during construction. If unexpected fills or underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. Depending upon depth of excavation and seasonal conditions, groundwater may be encountered in excavations on the site. Pumping from sumps may be utilized to control water within excavations. Well points may be required for significant groundwater flow, or where excavations penetrate groundwater to a significant depth. The stability of the subgrade may be affected by precipitation, repetitive construction traffic, or other factors. If unstable conditions are encountered or develop during construction, workability may be improved by scarifying and drying. Overexcavation of wet zones and replacement with granular materials may be necessary. Use of lime, fly ash, kiln dust, cement or geotextiles could also be considered as a stabilization technique. Laboratory evaluation is recommended to determine the effect of chemical stabilization on subgrade soils prior to construction. Lightweight excavation equipment may be required to reduce subgrade pumping. Subgrade Preparation: Areas of soft or loose soils may be encountered at foundation bearing depth after excavation is completed for footings or mats. When such conditions • exist beneath planned footing areas, the subgrade soils should be removed, replaced, and/or recompacted prior to placement of the foundation system. Subgrade soils beneath interior and exterior slabs, mat foundations, and beneath roadways should be scarified, moisture conditioned and compacted to a minimum depth of 12 inches. The moisture content and compaction of subgrade soils should be maintained until slab or pavement construction. Fill Materials and Placement: Clean on-site soils or approved imported materials may be used as fill material. Imported soils (if required) should conform to the following: Percent finer by weight Gradation (ASTM C136} 6" 100 3" 70-100 No. 4 Sieve 50-100 No. 200 Sieve 35 (max) • Liquid Limit 30(max) 13 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 Plasticity Index 15 (max) . Maximum expansive potential (%)* 1.5 *Measured on a sample compacted to approximately 95 percent of the ASTM D698 maximum dry density at about 3 percent below optimum water content. The sample is confined under a 100 psf surcharge and submerged. Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. Recommended compaction criteria for engineered fill is 95 percent of the maximum dry density (ASTM D698). On-site sands and/or imported soils should be compacted within a moisture range of 3 percent below to 3 percent above optimum unless modified by the project geotechnical engineer. The recommendations for placement and compaction criteria presented assume that fill depths will be less than 10 feet. Fills less than 10 feet, when placed and compacted as recommended in this report, will experience some settlement (generally 1 inch or less). The amount and rate of settlement will be increased if water is introduced into the fill. Excavation and Trench Construction: Excavations into the on-site soils will encounter • caving soils and possibly groundwater, depending upon the final depth of excavation. The individual contractor(s) should be made responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. The soils to be penetrated by the proposed excavations may vary significantly across the site. The preliminary soil classifications are based solely on the materials encountered in widely spaced exploratory test borings. The contractor should verify that similar conditions exist throughout the proposed area of excavation. If different subsurface conditions are encountered at the time of construction, the actual conditions should be evaluated to determine any excavation modifications necessary to maintain safe conditions. As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral distance from the crest of the slope equal to no less than the slope height. The exposed slope face should be protected against the elements. • 14 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 • Additional Design and Construction Considerations: Exterior Slab Design and Construction: Exterior slabs-on-grade, exterior architectural features, and utilities founded on or in backfill may experience some movement due to the volume change of the backfill. Potential movement could be reduced by: • minimizing moisture increases in the backfill. • controlling moisture-density during placement of backfill. • using designs which allow vertical movement between the exterior features and adjoining structural elements. • placing effective control joints on relatively close centers. Underground Utility Systems: All underground piping within or near the proposed structure should be designed with flexible couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts in foundation walls should be oversized to accommodate differential movements. It is strongly recommended that a representative of the geotechnical engineer provide full- time observation and compaction testing of trench backfill within building and pavement areas. • Corrosion Protection: Results of soluble sulfate testing indicate that ASTM Type I Portland cement is suitable for all project concrete on and below grade. However, if there is no (or minimal) cost differential, use of ASTM Type II Portland cement is recommended for additional sulfate resistance of construction concrete. Foundation concrete should be designed in accordance with the provisions of Section 318, Chapter 4, of the AC! Design Manual. Surface Drainage: Positive drainage should be provided during construction and maintained throughout the life of the proposed project. Infiltration of water into utility or foundation excavations must be prevented during construction. Surface features that could retain water in areas adjacent to the building or pavements should be sealed or eliminated. In areas where sidewalks or paving do not immediately adjoin the structure, we recommend that protective slopes be provided with a minimum grade of approximately 10 percent for at least 10 feet from perimeter walls. Backfill against footings, exterior walls and in utility trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration. Downspouts, roof drains or scuppers should discharge into splash blocks or extensions when the ground surface beneath such features is not protected by exterior slabs or paving. • 15 Geotechnical Engineering Report Terracon Proposed Pump House and Separator Facility Terracon Project No. 21085021 GENERAL COMMENTS • Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon should also be retained to provide testing and observation during the excavation, grading, foundation and construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include, either specifically or by implication, any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of our client for specific application to the • project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes are planned in the nature, design, or location of the project as outlined in this report, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes, and either verifies or modifies the conclusions of this report in writing. • 16 • Weld County Road 32 X X X X X X Proposed Septic Field . B-2 24 Proposed B-3_ e Tank Layout OO O P P-1 4 B-6 �. • a�0 O O 6 e5 o B-1 `� (9v osed Access R ad In Ground B-4, r prof Wash Pit ` Proposed Office OfBuildin_ I B-5 LEGEND N FIGURE I: BORING LOCATION DIAGRAM 1 PROPOSED TANK FARM AND SEPTIC SYSTEM S TEST BORINGS SOUTHWEST OF WELD COUNTY ROADS 37 & 32 WELD COUNTY, COLORADO • ® PERCOLATION TEST BORINGS Project Mng•. JRM Project No. 21085021 Designed By: i t r ra C®n Scale: 1"- 100' Checked By RLD Dote: 7/29/08 1289 FIRST AVENUE Approved By: JRU GREELEY, COLORADO 80631 Drawn By. JRM '.Not- Drawing based on Information gathered during site visit. NOT INTENDED FOR CONSTRUCTION le Name: 21085021.dwg Figure No. 1 LOG OF BORING NO. 1 Page 1 of 1 Client High Plains Disposal, Inc. SITE SW of WCR's 32&37 PROJECT • Platteville, Colorado Proposed Tank Farm&Septic System SAMPLES TESTS - DESCRIPTION z i > rn ew z zz ua O tail UU) > >- O JO -%O �.) zf-0 Approx.Surface Elev.: 5050 ft o D _ z I- Q 0) 5.0 o 0. D o) 0.5 TOPSOIL-8 inches 5040.5 ;! .. CLAYEY SAND occasional gravel, very dense to medium dense, light brown/buff *Moderately cemented @ 4 feet. —SC 1 RS 50/0.9 4 5- - *With gravel below 7 feet. _ i'. —SC 2 RS 35 3 10 14.5 5035.5 - 3 SS 24 19 BEDROCK 15 • claystone,firm to medium hard, gray with iron staining — 4 SS 32 15 20• 25- ,30 5020 30_- - 5 SS 21 25 BOTTOM OF BORING 0 co O C d Z O w 4 The stratification lines represent the approximate boundary lines r, between soil and rock types: in-situ,the transition may be gradual. WATER LEVEL OBSERVATIONS,ft BORING STARTED WL 4 None WD None AB BORING COMPLETED 8-4-0 WL [erracon RIG CME-55 FOREMAN JRM W WL AB checked after 1 day JOB# 21085021 LOG OF BORING NO. 2 Page 1 of 1 Client High Plains Disposal, Inc. a SITE SW of WCR's 32&37 PROJECT Platteville, Colorado Proposed Tank Farm&Septic System SAMPLES TESTS o o o_Q U DESCRIPTION m w 1- i E IE c) w > co cc z zz _ = 0 m w O Hz D Ow o Approx. Surface Elev.: 5050 ft a S z Lcirj m o a c. ,``'' `0.5 \TOPSOIL-6 inches / 5040.6 — SILTY SAND -SM 1 RS 44 3 medium dense, light brown 5047 J CLAYEY SAND -- occasional gravel, dense to medium dense, —SC 2 RS 50/0.9 3 117 light brown/buff 5 —` *Moderately cemented @ 4 feet. — . *With gravel below 7 feet. - - -SC 3 SS 35 2 10 - A 14 5036 - . - BEDROCK 15 - 4 SS 21 22 claystone,firm to medium hard, gray with iron staining — 20 5030 20 - 5 SS 50 20 109 BOTTOM OF BORING E q z L 0 0 CO 0 The stratification lines represent the approximate boundary lines N between soil and rock types: in-situ,the transition may be gradual. 0 WATER LEVEL OBSERVATIONS, ft BORING STARTED 8-4-08 lir Wt- V 1 None BORING COMPLETED 8-4-08 I WL N None WD s AB [Err 2COn RIG CME-55 FOREMAN JRM c WL AB checked after 1 day JOB# 21085021 1 LOG OF BORING NO. 3 Page 1 of 1 Client High Plains Disposal, Inc. SITE SW of WCR's 32&37 PROJECT ID Platteville, Colorado Proposed Tank Farm & Septic System SAMPLES TESTS O 4a DESCRIPTION z z ° > N trw z zz a ~ cn CO w a 0 Hz r Ow O Lad vo >- Lu Q O o z f- c� Approx. Surface Elev.: 5048 ft o z 1- cc m o o o. cn "•;-'.0.5 \TOPSOIL-6 inches x5047-.5 SILTY SAND —_ light brown 5045 -_ CLAYEY SAND occasional gravel, very dense to dense, —SC 1 SS 50/0.9 5 / light brown/buff 5- •• *Moderately cemented @ 4 feet. � *With gravel below 7 feet. • —SC 2 SS 37 2 10 • 13.5 5034.5 BEDROCK 3 SS 21 24 claystone,firm to soft, gray with iron 15 - — • staining — tom—20 5028 20 - 4 SS 15 24 BOTTOM OF BORING O. a I 0 m � 1 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ,the transition may be gradual. WATER LEVEL OBSERVATIONS, ft BORING STARTED 8-4-0 WL None WD None BORING COMPLETED 8-4- o WL T. AB erracon RIG CME-55 FOREMAN JRM cc WL AB checked after 1 day JOB# 21085021w LOG OF BORING NO. 4 Page 1 of 1 Client a High Plains Disposal, Inc. SITE SW of WCR's 32&37 PROJECT Platteville, Colorado Proposed Tank Farm&Septic System SAMPLES TESTS o DESCRIPTION 2 E zp o r!) W ≥ In tC W Z Z O >-0 ct • A rox. Surface Elev.: 5048 ft o S z m 3 o o a c~n pp "" ,`.0.5 \TOPSOIL-6 inches / 5017.5 — SILTY SAND -SM 1 SS 16 • medium dense, light brown 5045 SILTY,CLAYEY SAND — occasional gravel, medium dense to very —SC 2 SS 24 .. 6 dense, light brown/buff 5 -SM - *With gravel below 7 feet. Z 10-SC 3 SS 50/0.9 2 / SM '/,: 13 5035 BEDROCK — . 15 claystone,firm, gray with iron staining 5033 - 4 SS 21 20 BOTTOM OF BORING 15 0 -.,- •-.-- I-•a 0 Z C a m The stratification lines represent the approximate boundary lines s.,,-- between soil and rock types: in-situ,the transition may be gradual. g iik WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-4-08 lir WL -7 None WD T None AB BORING COMPLETED 8-4-08 a' WL Z [err acon RIG CME-55 FOREMAN JRM WL AB checked after 1 day JOB# 21085021 I % LOG OF BORING NO. 5 Page 1 of 1 Client High Plains Disposal,Inc. SITE SW of WCR's 32&37 PROJECT • Platteville, Colorado Proposed Tank Farm & Septic System SAMPLES TESTS _.i z Ga o DESCRIPTION 2 a z 0 } _ = co W } � co �Z z 2 Z Lu cc a w C/) F in �� D a 0�O Approx. Surface Elev.: 5046 ft o 2 z its-x':0.5 \TOPSOIL-6 inches / 5015.5 SILTY SAND — 3 light brown 5043 —_ . CLAYEY SAND -- occasional gravel, medium dense to dense, -SC 1 SS 25 7 light brown 5 X. — • *With gravel below 7 feet. • —SC 2 SS 44 3 • 10 - - A 13 C_? 5033 WEATHERED BEDROCK — 14.5 \claystone, gray with iron staining 5031.5 — 3 SS 16 22 • • 16 WEATHERED BEDROCK 5031 15 • sandstone, light gray l BOTTOM OF BORING ro 0 t- 0 O 2 cc O Q7 co The stratification lines represent the approximate boundary fines ,; between soil and rock types: in-situ,the transition may be gradual. 2 WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-4-0 T WL Q 13 WD 1 12 AB BORING COMPLETED 8-4-0811, WL Q lerracon RIG CME-55 FOREMAN JRM W- . S WL AB checked after 1 day JOB# 21085021, LOG OF BORING NO. 6 Page 1 of I Client High Plains Disposal,Inc. SITE SW of WCR's 32&37 PROJECT Platteville,Colorado Proposed Tank Farm & Septic System SAMPLES TESTS c .Q g DESCRIPTION >' e i i _ = ai w > o:w � zz Q 0. L' m wft. p �z >-� �W cc Approx. Surface Elev.: 5030 ft o S z m 8 o a E s'4 `'0.5 \TOPSOIL-6 inches / 5029.5 — CLAYEY SAND -SC 1 RS 49 3 111 3 medium dense, light brown 5027 SILTY SAND medium dense, light brown 5025 --SM 2 SS 19 3 BOTTOM OF BORING 5 0 0 ci • O 0 2 a O m The stratification lines represent the approximate boundary lines between soil and rock types: in-situ,the transition may be gradual. 0 ' WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-4-08 WL None WD I None BORING COMPLETED 8-4-08 0 WL 1IAB erracon RIG CME-55 FOREMAN JRM o WL AB checked after 1 day JOB# 21085021 LOG OF BORING NO. P-1 Page 1 of 1 Client High Plains Disposal, Inc. SITE SW of WCR's 32& 37 PROJECT • Platteville, Colorado Proposed Tank Farm &Septic System SAMPLES TESTS a O a DESCRIPTION z N w — Z Z Z}U' cn CO w O _ u LL a a D O J QO n' z Approx. Surface Elev.: 5045 ft o D z 1- CC CO 3 O On. k`r',. 0.5 \TOPSOIL-6 inches / 5011.5 -� SILTY SAND — loose, light brown 5 8 5037 -SM 1 SS 7 6 BOTTOM OF BORING • a a 0 z EE 0 The stratification lines represent the approximate boundary lines r.-, between soil and rock types: in-situ,the transition may be gradual. WATER LEVEL OBSERVATIONS, ft BORING STARTED 8-4-0 WL Q None WD None AB BORING COMPLETED 8-4-0W WL I erracon RIG CME-55 FOREMAN JRM WL AB checked after 1 day JOB # 21085021 4 2 NN -2 z \' J Q , 'aS -4 \IN) -6 -8 _... 10 I 100 1,000 10,000 PRESSURE,psf Specimen Identification Classification Yd, pcf WC,% • 2 4.0ft Clayey Sand 117 3 0 Notes: Water Added @ 500 psf. 0 0 • SWELL CONSOLIDATION TEST Project: Proposed Tank Farm & Septic System re ��®� Site: SW of WCR's 32 &37 Platteville, Colorado o Job#: 21085021 Date: 4 • 2 - - =1L- -2 - -- -I z H -6 • • • -8 -10 10 100 1,000 PRESSURE, psf Specimen Identification Classification Yd, pcf WC,% • 6 1.0ft Clayey Sand 111 3 O 0 Notes: Water Added @ 150 psf. O CL a SWELL CONSOLIDATION TEST Project: Proposed Tank Farm &Septic System z lierracon Site: SW of WCR's 32&37 Platteville, Colorado o Job#: 21085021 O Date: 60 @ CH 50 • P L A S 40 T I C • 30 Y N• 20 X 10 • CL-ML A ML O(}II 20 40 60 80 100 LIQUID LIMIT Specimen Identification LL PL PI %Fines Classification • 1 9.0ft 24 16 8 26 CLAYEY SAND(SC) m 2 1.0ft NP NP NP 18 SILTY SAND(SM) ♦ 4 1.0ft NP NP NP 39 SILTY SAND(SM) . * 4 9.0ft 18 14 4 27 SILTY, CLAYEY SAND(SC-SM) O P-1 7.0ft NP NP NP 35 SILTY SAND(SM) F- O C z O m 0- 2 co ATTERBERG LIMITS RESULTS • Project: Proposed Tank Farm& Septic System lierracon Site: SW of WCR's 32 & 37 Platteville, Colorado Job#: 21085021 O U GENERAL NOTES DRILLING &SAMPLING SYMBOLS: • SS: Split Spoon- 1-3/8"I.D.,2"O.D.,unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube-2"O.D.,unless otherwise noted PA: Power Auger RS: Ring Sampler-2.42"I.D.,3"O.D.,unless otherwise noted HA: Hand Auger DB: Diamond Bit Coring-4",N,B RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary The number of blows required to advance a standard 2-Inch O.D. split-spoon sampler(SS) the last 12 inches of the total 18-inch perotratlon with a 140-pound hammer falling 30 inches is considered the"Standard Penetration"or'N-value'. WATER LEVEL MEASUREMENT SYMBOLS: WL: Water Level WS: While Sampling N/E: Not Encountered WCI: Wet Cave in WD: While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB: After Boring ACR: After Casing Removal Water levels Indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils,the Indicated levels may reflect the location of groundwater. In low permeability soils,the accurate determination of groundwater levels may not be possible with only short-term observations. DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a#200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a#200 sieve; they are principally described as clays If they are plastic,and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation,coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS • Standard Unconfined Penetration or Standard Penetration Compressive N-value(SS) or N-value(S1 Strength,Qu, psf Blows/Ft. Consistency Blows/FL Relative Density <500 <2 Very Soft D—3 Very Loose 500 - 1,000 2-3 Soft 4--9 Loose 1,001 -- 2,000 4.6 Medium St:ff 10-29 Medium Dense 2,001 - 4,000 7-12 Stiff 30—49 Dense 4,001 -- 8,000 13-26 Very Stiff 50+ Very Dense 8,000 I. 26+ Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY Descriptive Term(s) of other Percent of Valor Component constituents Dry Weight of Sample Particle Size Trace <15 Boulders Over 12 in.(300mm) With 15-29 Cobbles 12 in.to 3 in. (300mm to 75 rem) Modifer >30 Gravel 3 in.to#4 sieve(75mm to 4.75 mm) Sand #4 to#200 sieve(4.75mm to 0.075mm) RELATIVE PROPORTIONS OF FINES Silt or Clay Passing#200 Sieve(0.075mm) Descriptive Term(s) of other Percent of PLASTICITY DESCRIPTION constituents Dry Weight Term Plasticity index Trace <5 Non-plastic 0 With 5-12 Low 1-10 Modifiers >12 Medium 11-30 High 30+ IIII rerracon UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests* Soil Classification • Group Symbol Group Name° Coarse Grained Soils Gravels Clean Gravels Cu 2 4 and 1s Cc s 3` GW Well-graded gravel' More than 50%retained More than 50%of coarse less than 5%fines` Cu<4 and/or 1>Cc>3` GP Poorly graded gravel` fraction retained on on No.200 sieve No.4 sieve Gravels with Fines Fines classify as ML or MH GM Silty gravel'°" More than 12%fines` Fines classify as CL or CH GC Clayey graveP°" Sands Clean Sands Gin 6 and is Cc s 3` SW Well-graded sand' 50%or more of coarse Less than 5%fines° Cu<6 and/or 1>Cc>3` SP Poorly graded sand' fraction passes No.4 sieve Sands with Fines Fines classify as ML or MH SM Silty sand"' More than 12%fines° Fines Classify as CL or CH SC Clayey sand°"' Fine-Grained Soils Silts and Clays Inorganic PI>7 and plots on or above"A"line' CL Lean dayw' 50%or more passes the Liquid limit less than 50 PI<4 or plots below"A"line' ML Silt"`" No.200 sieve organic Liquid limit•oven dried ""Organic clay"- ""<0.75 OL Liquid limit-not dried Organic new,. Silts and Clays inorganic PI plots on or above"A"line CH Fat clay" Liquid limit 50 or more PI lots below"A"line MH Elastic Siff""' organic Liquid limit-oven dried <0 75 OH Organic day""' Liquid limit-not dried Organic silt`"4° Highly organic soils Primarily organic matter,dark In color,and organic odor PT Peat ABased on the material passing the 3-In.(75-mm)sieve "If fines are organic,add'with organic fines"to group name. elf field sample contained cobbles or boulders,or both,add'with cobbles ' If soil contains 2 15%gravel,add'with gravel"to group name. or boulders,or both"to group name. If Atterberg limits plot in shaded area,soil(s a CL-ML,silty clay. iikGravels with 5 to 12%fines require dual symbols: GW-GM well-graded Klf soil contains 15 to 29%plus No.200.add'with sand'or"with gravel with silt,GW-GC well-graded gravel with clay,GP-GM poorly gravel,"whichever is predominant graded gravel with silt,GP-GC poorly graded gravel with day. t If soil contains 2 30%plus No.200 predominantly sand,add °Sands with 5 to 12%lines require dual symbols: SW-SM well-graded 'sandy'to group name. sand with silt,SW-SC well-graded sand with clay,SP-SM poorly graded hi If soil contains 2 30%plus No.200,predominantly gravel, sand with silt,SP-SC poorly graded sand with day add"gravelly to group name. ECU=DedDto Ce= (Da o"PI 2 4 and plots on or above"A"line. Dmx Deo Pi<4 or plots below'A'line. F If soil contains 2 15%sand,add'with sand"to group name. PPI plots on or above'A"line. °If fines classify as CL-ML,use dual symbol GC-GM,or SC-SM. ° PI plots below'A'line. 60 i i For classification of fine-grained soils and fine-grained fraction 50 _of coarse-gralnod soils Jo°"' Jpe Equation of'A'-line .4, "p' Horizontal at PI=410 LL=25.5. I ,r..-...— X 40 — then PI.0,73(LL•20) ....-.....___ _____„t.__ � p U'Equation of -line G�o 2 Vertical at LL.16 to PI=7, } 30 — then PI=0.9(LL-6) / Q O",5 O 20 0' MH or OH 0. 10 i 7 ML or OL a 1 I 0 • 0 10 16 20 30 40 50 60 70 60 90 100 110 LIQUID LIMIT(LL) lierracon _ Form 111-6198 Hello