SOIL STABILITY ANALYSES

Transcription

1 AMERICAN WATER ENGINEERING SERVICES, LLC SOIL STABILITY ANALYSES OMLR 1 PERMIT APPLICATION VARRA PIT 2 AWES PROJECT # 0-0-VARRA July 27, 1 Prepared for: Prepared by: Varra Companies, Inc. AWES, LLC 80 Gage Street 809 Four Star Ct. Frederick, CO 8016 Fort Collins, CO 802 AWES 809 Four Star Court, Fort Collins, CO 802

2 Introduction The following report presents the results of a slope stability analysis for a proposed open cut gravel extraction operations at the Varra Pitt 2 operations near Platteville, Colorado. This analysis was performed at the request of Varra Companies, Inc., (Varra). This report is being submitted in partial fulfillment of an OMLR 1 Mine Permit Application. Background Information The proposed gravel quarry is located in the NW1/, S33, T3N, R67W of the 6 th Principal Meridian. The surrounding land use consists of agricultural, rural residential, commercial and open-cut gravel quarry operations. The proposed mine area occupies an estimated 2 acres. The water table at the site is located in unconsolidated alluvial deposits with an averaage depth to water of approximately six feet below ground surface. Soil conditions generally consist of varying thicknesses of top soil underlain by sand and gravel deposits, which in turn are underlain by sandy and argillaceous siltstones. Over the entire area the average saturated thickness of the sand and gravel deposits (prior to mining) is estimated at about 3 feet. It is our understanding that the sand and gravel will be dewatered during aggregate extraction. The site location is presented on Figure 1. Previous Investigations Terracon Consultants, Inc., (Terracon) conducted a sand and gravel study in September 08. The study consisted of drilling 22 soil borings from ground surface to bedrock to determine the potential aggregate mass within the proposed mine boundary. Selected sand and gravel samples were obtained for grain size distribution determinations. The depth to bedrock over the site varied between 13 and feet below ground surface. The majority of the study area consists of three to five feet of clayey sand underlain by sand and gravel with occasional clayey sand, silty sand and sand lenses. Bedrock consists of sandstone, siltstone and claystone. The Terracon report is provided as Attachment A.

3 Slope Stability Analysis Pit 2 Varra 1 Permit Application Weld County, Colorado Page 2 Overview of Stability Analyses The depth to bedrock varies between 13 and feet across the study area with the bedrock surface dipping steeply to the northwest. Soil strength testing was not performed as part of the Terracon study and in the absence of strength test data the following soil strength parameters were used in the stability analysis. Table 1 Soil Strength Properties Material Wet Unit Weight Saturated Unit Weight Cohesive Friction (lbs/cu ft.) (lbs/cu ft.) Intercept (PSF) Angle Top Soil Poorly Graded Sand Sand & Gravel Weathered Bedrock Bedrock The assumptions used in the bank stability analysis include the following: The static depth to groundwater at the distance to no pumping influence is 6 feet below ground surface and the water table will intersect the pit bank just above the mine floor (seepage face) during steady state dewatering. The pit depth will vary between 2 and feet below grade. Load surcharges of 2,00 pounds per square foot were simulated. During extraction activities the pit bank slope will vary between 3H:1V and 1.2H:1V. The software package PC-STABL was used to evaluate slope stability. Simulations using Spencer, Modified Bishop and Modified Janbu methods were run to determine the most conservative

4 Slope Stability Analysis Pit 2 Varra 1 Permit Application Weld County, Colorado Page 3 safety factor. The soil strength properties used in the analysis are presented on computer generated data sheets which are presented in Attachment B. Stability analyses were ran for three scenarios a 2 foot mine depth, a 3 foot mine depth and a foot mine depth. A series of trial and error simulations were ran to determine the mine wall slopes that would meet a safety factor of 1.3 or greater. A review of Attachment B shows proposed bank profiles are stable with a calculated safety factors that vary between 1.3 and 1.6. Discussion Slope failure analyses for proposed open cut gravel operations at the Varra Pitt 2 site indicate proposed slope cuts will be stable for dewatered or static water table conditions. As the depth to bedrock varies greatly it is recommended that the lower half (modeled at %) of the mine slope be maintained at 3H:1V and the remaining mine wall sloped at 1.2H:1V. This allows for maximum material extraction while maintaining an adequate safety factor. If any significant modifications to proposed pit wall slopes occur this analysis may not be representative of site conditions and additional simulations are recommended. Comments The discussions and recommendations in this report represent our professional opinions. Our conclusions, opinions and recommendations are based from information available at this time and we do not guarantee that undiscovered conditions will not become evident in the future. AWES' report was prepared in accordance with currently accepted engineering practices at this time and location and no other warranties, representations or certifications are implied or intended.

5 Slope Stability Analysis Pit 2 Varra 1 Permit Application Weld County, Colorado Page This report was prepared by AWES, LLC. Date: July 27, 1 Joby L. Adams, P.G. Principal/Hydrogeologist

6 REFERENCES Terracon Consultants, Inc., 08. Preliminary Geotechnical Engineering Report and Sand/Gravel Study, Weld County, Colorado. Prepared for EDAW/AECOM, Fort Collins, CO, September 26, 08.

7 FIGURE

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9 ATTACHMENT A Geotechnical Study Results

10 PRELIMINARY GEOTECHNICAL ENGINEERING REPORT AND SAND/GRAVEL STUDY PROPOSED SAND/GRAVEL MINE LAFARGE BEARSON PARCEL SE CORNER OF COUNTY ROAD 17 AND COUNTY ROAD 28 WELD COUNTY, COLORADO Terracon Project No September 26, 08 PRELIMINARY DRAFT SUBMITTAL Prepared for: EDAW/AECOM East Mountain Avenue Fort Collins, Colorado Attn: Mr. John Ko Prepared by: Terracon Consultants, Inc. 1 North Howes Street Fort Collins, Colorado 8021 Phone: Fax:

11 Consulting Engineers and Scientists September 26, 08 1 N Howes Street Fort Collins, Colorado 8021 Phone (970) Fax (970) EDAW/AECOM East Mountain Avenue Fort Collins, Colorado 802 Attn: Re: Mr. John Ko Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine Southeast Corner of County Road 17 and County Road 28 Weld County, Colorado Terracon Project No Terracon has completed geotechnical engineering exploration for the proposed project to be located at the southwest corner of County Road 17 and County Road 28 in Weld County, Colorado. This study was performed in general accordance with the proposal prepared by EDAW (Project # ) dated September, 08. The results of our engineering study are attached. These results include the Boring Location Map, 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. Other design and construction recommendations, based upon geotechnical conditions, are presented in the report. Supplementary geotechnical engineering exploration should be performed at the site when final design plans become available and preliminary design studies are complete. Supplemental geotechnical explorations will be used to confirm or modify the recommendations contained in this preliminary report. Delivering Success for Clients and Employees Since 196 More than 9 Offices Nationwide ii

12 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL 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 testing, inspection, design and consulting services. Sincerely, TERRACON CONSULTANTS, INC. Raymond L. Denton, II, P.E. Geotechnical Department Manager Copies to: Addressee () iii

13 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL TABLE OF CONTENTS Page No. Letter of Transmittal... ii INTRODUCTION... 1 SITE EXPLORATION... 1 Field Exploration... 1 Laboratory Testing... 2 SITE CONDITIONS... 3 SUURFACE CONDITIONS... 3 Economic Mineral Potential... 3 Soil and Bedrock Conditions... Field and Laboratory Test Results... Groundwater Conditions... 6 PRELIMINARY RECOMMENDATIONS... 6 Sand/Gravel Mining and Geotechnical Considerations... 6 Other Geotechnical Considerations... 7 GENERAL COMMENTS... 7 Figure No. BORING LOCATION DIAGRAM... 1 APPENDIX A: LOGS OF BORING APPENDIX B: LABORATORY TEST RESULTS APPENDIX C: GENERAL NOTES iv

14 PRELIMINARY GEOTECHNICAL ENGINEERING REPORT AND SAND/GRAVEL STUDY INTRODUCTION PROPOSED SAND/GRAVEL MINE SE CORNER OF CR 17 AND CR 28 WELD COUNTY, COLORADO Terracon Project No September 26, 08 This report contains the results of our preliminary geotechnical engineering exploration for the proposed project to be located at referenced site. The site is located at the southeast corner of the intersection of Weld County Road 17 and Weld County Road 28 in Weld County, Colorado. The purpose of these services is to provide information and preliminary geotechnical engineering recommendations relative to: subsurface soil and bedrock conditions. groundwater conditions. feasibility for use of site as a gravel mining pit 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 Based on preliminary information provided by LaFarge, the proposed project will include the development of an approximate 168-acre parcel. Currently the site is being considered to be utilized as a sand and gravel mining operation pit. SITE EXPLORATION PROCEDURES The scope of the services performed for this project to date have included site reconnaissance by an geotechnical engineer, a subsurface exploration program, laboratory testing and preliminary engineering analysis. Field Exploration: A total of 22 test borings were drilled between September 3, 08 to September 1, 08 to depths of about to 63 feet below existing site grade at the approximate locations shown on the Boring Location Diagram, Figure 1. The borings were drilled across the site at approximate 00 foot grid spacings in order to asses the general subsurface conditions. Portions of the site were inaccessible at this time due to current 1

15 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL agricultural operations. Borings in these locations will be drilled at a later date. The borings were advanced with a truck-mounted drilling rig, utilizing -1/-inch inside diameter (approx 8- inch outside diameter) hollow-stem, auger. The borings were located in the field by a hand held GPS. Elevations were estimated at each boring location by interpolation from contours indicated on topographic mapping provided by Northern Engineering. 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 an engineering geologist during the drilling operations. At selected intervals, samples of the subsurface materials were taken by driving split-spoon and ring barrel samplers. Representative bulk samples of subsurface materials were also obtained at approximate to -foot intervals. Penetration resistance measurements were obtained by driving the split-spoon or ring barrel into the subsurface materials with a 10-pound hammer falling 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. A majority of the borings were backfilled after drilling operations due to safety considerations; therefore subsequent groundwater measurements were not obtained in these borings. 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 gradation characteristics 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 assessing the feasibility of utilizing the site as a sand/gravel pit and for the preliminary geotechnical engineering analyses. Laboratory tests were performed in general accordance with the applicable local or other accepted standards. 2

16 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL SITE CONDITIONS The site was vacant and to our knowledge had not been previously developed and was used for agricultural purposes. The site was bounded on the north by County Road 28 and agricultural land beyond, and on the east, south and west by agricultural property. The ground surface was rowed/tilled and generally soft and moist due to the on-going agriculture and irrigation practices. Vegetation consisted of crops of corn. An existing single family residence and associated outbuildings was located at the approximate center of the site with access to the north to County Road 28. Site drainage was generally poor and in the form of surface sheet flow. Several areas of standing water were noted, particularly at the northeast corner of the site. Additionally, several underground petroleum lines and a tank installation is present on the site. SUURFACE CONDITIONS Geology: Surficial geologic conditions at the site, as mapped by the U.S. Geological Survey (USGS) ( 1 Colton, 1978), consist of the Piney Creek Alluvium of Quaternary Age. This material generally consists of sandy to gravely alluvium. These materials, as mapped in this area, are generally on the order of about to feet in thickness. Bedrock underlying the surface units consists of the Fox Hills Sandstone of Upper Cretaceous Age. This formation is generally comprised of silty siltstone interbedded with gray fissile shale. The thickness of this unit has been reported to be on the order of 0 to 00 feet. Economic Mineral Potential: Mapping performed by the USGS ( 2 Schwochow, Shroba, and Wicklein, 197) indicates that the site lies in an area of flood-plain and valley fill deposits along present stream courses with stream deposits consisting of relatively clean and sound gravel. This is consistent with the materials encountered in our borings. Mapping performed by the USGS ( 3 Rodger B. Colton, 197) indicates that the site contains a gravel deposit underlying flood plains and terraces. The materials are described as pebbles and clasts generally well rounded, unweathered, and contain little deleterious lime (CaCO3). 1 Colton, Roger B., 1978, Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado, United States Geological Survey, Map I-8-G. 2 Schwochow, S.D., Shroba, R.R., and Wicklein, P.C., 197, Sand, Gravel, and Quarry Aggregate Resources of the Colorado Front Range Counties, Colorado Geological Survey, Special Publication -A, Plate 1. 3 Rodger B. Colton., and Fitch, Harold R., 197, Map Showing Potential Sources of Gravel and Crushed Rock Aggregate in the Boulder-Fort Collins-Greeley Area, Front Range Urban Corridor, Colorado, United States Geological Survey, Map I-8-D. 3

17 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL Clasts are composed chiefly of quartzite, granite, gneiss, and pegmatite. Grain size distribution by weight is mapped near the area as 3% clay and silt, % sand, 9% granular gravel, and % pebbles. The material contains few or no reactive constituents and is a source of quality gravel for the Longmont area. Gravel thicknesses of these deposits mapped in the area range from approximately 1 to 28 feet in thickness. Based on the materials encountered in our borings, it is likely that commercially extractable mineral deposits will be encountered on the project site. Due to the relatively flat nature of the site, geologic hazards at the site are anticipated to be low. Seismic activity in the area is anticipated to be low, and the property should be relatively stable from a structural standpoint. With proper site grading around the proposed mine, erosional problems at the site should be reduced. Soil and Bedrock Conditions: As presented on the Logs of Borings, surface soils to depths of about 13 to feet consist predominantly of overburden sands with gravels. Claystone, siltstone, and/or sandstone bedrock was encountered below the overburden sands and extended to the total depths of exploration of about to 63 feet below existing site grade. A bedrock contour map has been generated based on preliminary information and is provided in Figure 2. Field and Laboratory Test Results: Field test results indicate the sand soils vary from loose to very dense in relative density. The bedrock varies from medium hard to hard in hardness. Gradations performed on the bulk samples obtained from the test borings indicate that the overburden materials generally classify as sands with the following characteristics: Boring No. Sample depth Depth to Bedrock (ft) %gravel %sand %silt/clay B1 9-1 ft B ft B ft B2 - ft B2 0-0 ft B3-0 ft B3 9- ft B - ft B - ft B 0-7 ft B 0- ft B - ft B - ft B -0 ft B 0-7 ft

18 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL B6 - ft B6-2 ft B8 0- ft B8 - ft B - ft B 0-7 ft B11 - ft B11 - ft B13 0- ft B13 - ft B13 - ft B13-0 ft B16 - ft B16 - ft B17 9- ft B17 - ft B17-38 ft B19 0- ft B19 - ft B21 0- ft B21 - ft B22 0- ft B22 - ft B22 - ft B ft B ft B ft B ft B2 - ft B2-1 ft B26 0- ft B26 - ft B27 - ft B27 - ft B27-3 ft B ft B ft B ft B ft Average It should be noted that the gradations were performed primarily on bulk samples obtained from auger cuttings. Efforts were made to obtain a representative sampling of the subsurface materials at the depths indicated, however the depths of the samples and gradations presented

19 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL should be considered approximate only. The gradation analysis curves are presented at the conclusion of the report. Groundwater Conditions: Groundwater was generally encountered at depths of about 3 to feet (average of about 6 feet) below existing site grade in the test borings at the time of field exploration. Groundwater was encountered at a depth of about 0 at the southeast corner of the site. A groundwater contour map has been generated based on preliminary information and has been provided in Figure 3. A majority of the borings were backfilled after drilling due to cave-in conditions and safety considerations, therefore subsequent groundwater measurements were not obtained in these borings. 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. Based upon review of U.S. Geological Survey Maps, ( Hillier, et al, 1979), regional groundwater beneath the project area is expected to be encountered in unconsolidated alluvial deposits on the site at depths ranging from to and greater than feet below present ground surface. Fluctuations in groundwater levels can best be determined by implementation of a groundwatermonitoring plan. Such a plan would include installation of groundwater-monitoring wells and periodic measurement of groundwater levels over a sufficient period of time. The possibility of groundwater fluctuations should be considered when developing design and construction plans for the project. PRELIMINARY RECOMMENDATIONS The preliminary recommendations presented in this report are based on the assumption that the subsurface conditions do not deviate appreciably from those encountered in the borings. Supplementary geotechnical engineering exploration should be performed at the site upon completion of initial design studies. Supplemental geotechnical explorations will be used to confirm or modify the recommendations contained in this preliminary report. Sand/Gravel Mining and Geotechnical Considerations: Based upon the materials encountered during the preliminary geotechnical exploration of the site and the results of the laboratory testing, the site appears to be feasible for the purpose of mining various quantities of 1 Hillier, Donald E.; and Schneider, Paul A., Jr., 1979, Depth to Water Table ( ) in the Boulder-Fort Collins- Greeley Area, Front Range Urban Corridor, Colorado, United States Geological Survey, Map I-8-I. 6

20 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL sand and gravel sized aggregate. However, the majority of the gravels are smaller than ¾ - inches in diameter. The depth of the sand and gravel overburden is approximately 13 to feet with the average depth about 39 feet below existing site grade. Relatively shallow bedrock was encountered at the site in Boring Nos. 2, 26, and 29 at depths of 1 to 23 feet. We recommend that LaFarge analyze the gradations provided herein carefully to determine the economic and physical viability of developing the site for mining. If the preliminary assessments look favorable for mining the site, we recommend that further exploration be performed with a reverse air circulation drill rig in order to collect additional sand and gravel samples since large samples of the subsurface materials are not practical with conventional hollow stem auger methods due to heaving sands and groundwater conditions. As previously outlined, groundwater was encountered across the site at depths ranging from about 3 to feet below existing site grade. If deeper mining operations are being considered, dewatering of the site will likely be required and an experienced contractor should be consulted to assist with determining the feasibility of dewatering in such conditions. It has been our experience that slurry cut-off walls are effective for dewatering when the depth to bedrock is less than about 0 to 60 feet due to the practical installation depths of these systems. Slurry walls must typically be keyed-in to bedrock or other relatively impervious stratum in order to be effective. Therefore, the use of very large equipment may be required for slurry wall installations, based on the depth to bedrock at the site. Other dewatering alternatives for the purpose of mining would consist of installing well-points in specific areas that are being excavated. Other Geotechnical Considerations: Protection of the existing single family residence will require particular care during excavation and dewatering activities. Significant dewatering of the site will likely cause some settlement of the structure and associated outbuildings. Additional analysis will be required to determine the approximate magnitude of this settlement. Slope stability analyses will be required to determine the required slope inclinations required to maintain stability of the structure during mining operations. Other options for stabilizing the structure could include shoring systems. A thorough evaluation and documentation of the existing structure conditions is recommended prior to beginning any construction activities. GENERAL COMMENTS Supplemental exploration and analyses should be undertaken in order to develop final design parameters and to confirm and/or modify the preliminary recommendations and conclusions contained in this report. This report should not be relied upon for final design, and should only be used for planning and budget purposes. 7

21 Preliminary Geotechnical Engineering Report and Sand/Gravel Study Proposed Sand/Gravel Mine- Weld County, Colorado Terracon Project No Terracon PRELIMINARY DRAFT SUBMITTAL 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 preliminary 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 preliminary 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. 8

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25 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 1 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SANDY LEAN CLAY Medium stiff, brown, gray SILTY SAND Loose to medium dense, brown, tan BOREHOLE_ GPJ BORING.GDT 9/26/ CLAYSTONE Gray, very hard BOTTOM OF BORING The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL WL WL WD 2.6 Initial Water Level Reading AB 6 0/0. BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN CMG APPROVED RLD JOB # 0806

26 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 2 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf. SANDY LEAN CLAY Soft, dark brown SAND WITH GRAVEL Medium dense, tan 1 RS RS BOREHOLE_ GPJ BORING.GDT 9/26/08 63 SILTSTONE Hard, blue/greyish BOTTOM OF BORING The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL WL WL.0 WD BACKFILLED 8 9 BORING STARTED RIG 0/0.3 0/0.3 CME 7 FOREMAN Initial Water Level Reading APPROVED RLD JOB # 60 BORING COMPLETED EB 0806

27 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 3 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SANDY LEAN CLAY Medium stiff, dark brown 1 RS 6 9 SAND WITH GRAVEL Medium dense, tan 2 3 RS SILTSTONE Hard, blue/greyish 0 7 BOTTOM OF BORING 8 3 0/0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL 9.0 WD BACKFILLED BORING COMPLETED WL RIG CME 7 FOREMAN EB WL Initial Water Level Reading APPROVED RLD JOB # 0806

28 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SILTY SAND Brown, wet at 9. CLAYEY SAND Dark brown SANDSTONE Very hard, light brown/reddish BOTTOM OF BORING 0 3 0/0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL.0 WD 2.2 AB WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG HP Buggy FOREMAN PG APPROVED RLD JOB # 0806

29 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SAND WITH GRAVEL Light brown SANDSTONE Very hard, light brown/reddish BOTTOM OF BORING /0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN PG APPROVED RLD JOB # 0806

30 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 6 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SANDY CLAY Medium stiff, dark brown CL 1 RS 8 8 SAND WITH GRAVEL Medium dense, brown 2 RS 2 1 GRAVEL WITH SAND Tan 3 2 SAND WITH GRAVEL Brown SILTSTONE Hard, blue/greyish /0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 60 BOTTOM OF BORING /0.2 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL 8.0 WD 2.7 AB BORING COMPLETED WL RIG CME 7 FOREMAN EB WL Initial Water Level Reading APPROVED RLD JOB # 0806

31 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 8 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf 2 POORLY GRADED GRAVEL WITH SAND Brown SAND WITH GRAVEL Loose to medium dense, brown 1 RS RS 33 1 RS 6 RS RS 22 8 RS 3 RS 0 11 RS 8 SILTSTONE Hard, blue/greyish 6 0 BOTTOM OF BORING /.3 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN EB APPROVED RLD JOB # 0806

32 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf CLAYEY SAND Very loose, dark brown 1 RS 8 SAND WITH GRAVEL Medium dense, brown 2 3 RS SILTSTONE Hard, greyish/blue 0 7 BOTTOM OF BORING 8 0/0.3 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL 6.0 WD BACKFILLED BORING COMPLETED WL RIG CME 7 FOREMAN EB WL Initial Water Level Reading APPROVED RLD JOB # 0806

33 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 11 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf. 9 SANDY CLAY Medium stiff, brown SILTY SAND Orangeish brown SAND WITH GRAVEL Brown CL SW 1 2 RS RS SILTSTONE Hard, greyish blue 6 0/.3 0 BOTTOM OF BORING 0 7 0/0. BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL 9.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN EB APPROVED RLD JOB # 0806

34 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 13 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf GRAVEL WITH SAND Well sorted, brown 7 SAND WITH GRAVEL Reddish brown SANDSTONE Very hard, light brown/olive 0. BOTTOM OF BORING 0 6 NR 0/0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN PG APPROVED RLD JOB # 0806

35 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 16 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf 2 CLAYEY SAND Brown SAND WITH GRAVEL Very loose to loose, brown 1 RS RS SILTSTONE Hard, grey BOTTOM OF BORING 0 3 0/0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN EB APPROVED RLD JOB # 0806

36 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 17 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf CLAYEY SAND Brown SC 1 RS 7 9 SAND WITH GRAVEL Loose, brown 2 3 RS 16 1 GRAVEL WITH SAND (0." to 1." gravels) 2 29 SAND WITH GRAVEL tan 3 38 SILTSTONE Medium hard to hard, blueish/grey /0. BOTTOM OF BORING 8 0/0.3 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL 8.0 WD BACKFILLED BORING COMPLETED WL RIG CME 7 FOREMAN EB WL Initial Water Level Reading APPROVED RLD JOB # 0806

37 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 19 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf 2 CLAYEY SAND Dark brown POORLY GRADED SAND WITH TRACE GRAVEL Brown SAND WITH GRAVEL Medium dense, trace silt and clay at 1 ft. SC RS RS SILTSTONE Hard, greyish/olive 7 0/0.3 0 BOTTOM OF BORING 0 8 0/0.3 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL.0 WD BACKFILLED BORING COMPLETED WL RIG CME 7 FOREMAN EB WL Initial Water Level Reading APPROVED RLD JOB # 0806

38 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 21 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf CLAYEY SAND Medium stiff to very stiff, brown SC 1 RS 7 9 SAND WITH GRAVEL Brown 2 3 RS SILTSTONE Hard, grey 2 BOTTOM OF BORING 3 0/0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN EB APPROVED RLD JOB # 0806

39 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 22 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SANDY CLAY Dark brown 13 SILTY SAND light brown, trace gravel 1 CL SANDSTONE Hard, light brown BOTTOM OF BORING /0.6 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL 6.0 WD 3.2 AB BORING COMPLETED WL RIG HP Buggy FOREMAN PG WL Initial Water Level Reading APPROVED RLD JOB # 0806

40 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 23 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SILTY SAND Brown, tan 1 11 SANDY LEAN CLAY Brown SILTY SAND Brown, tan 1 2 SAND WITH GRAVEL Tan, brown 3 2 SILTY SAND Brown, tan CLAYSTONE Very hard, grey BOTTOM OF BORING 6 1 0/0.1 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN CMG APPROVED RLD JOB # 0806

41 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 2 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf POORLY GRADED SAND WITH SILT Very loose to loose, brown SP SM 1 RS 6 9 CLAYEY SAND Brown SC 2 3 RS 1 1 SILTY SAND Brown, with trace gravel from 16 ft. to 22 ft SILTSTONE Hard, grey/olive BOTTOM OF BORING 2 6 0/0. BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL 8.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN EB APPROVED RLD JOB # 0806

42 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 2 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf 1 SILTY SAND Trace gravel CLAYEY SAND Trace gravel, brown SILTY SAND Very loose to medium dense, brown SC SM RS RS CLAYSTONE Hard, grey 1 BOTTOM OF BORING 0/0. BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL.0 WD BACKFILLED BORING COMPLETED WL RIG CME 7 FOREMAN EB WL Initial Water Level Reading APPROVED RLD JOB # 0806

43 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 26 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf CLAYEY SAND Fine grained, brown SC CLAY Dark brown CLAYSTONE Hard, grey/blackish BOTTOM OF BORING /. BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft WL 3.0 WD BACKFILLED WL WL Initial Water Level Reading BORING STARTED BORING COMPLETED RIG CME 7 FOREMAN PG APPROVED RLD JOB # 0806

44 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 27 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SILTY SAND WITH TRACE FINE GRAVEL Brown SAND WITH GRAVEL Brown SANDSTONE Hard, light brown 3 0 BOTTOM OF BORING 0 7 0/0.6 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL 7.0 WD AB BORING COMPLETED WL RIG HP Buggy FOREMAN PG WL Initial Water Level Reading APPROVED RLD JOB # 0806

45 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 28 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SILTY SAND Brown, tan, medium dense SM CLAYSTONE Very hard, grey BOTTOM OF BORING 3 0/0.2 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL 0 WD DRY AB BORING COMPLETED WL RIG CME 7 FOREMAN CMG WL Initial Water Level Reading APPROVED RLD JOB # 0806

46 SITE Lafarge SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado LOG OF BORING NO. 29 ARCHITECT / ENGINEER PROJECT SAMPLES Bearson Gravel Study TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION DEPTH, ft. USCS SYMBOL NUMBER TYPE RECOVERY, in. BLOWS / ft. WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf SILTY SAND Brown, tan SM 2 SM SILTY SAND WITH GRAVEL Tan, brown, very dense SILTY SAND Brown, tan SANDSTONE Very hard, grey, Fe Ox 1 SM /0.6 0/0.6 0/ BOTTOM OF BORING 7 1 0/0.1 BOREHOLE_ GPJ BORING.GDT 9/26/08 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OERVATIONS, ft BORING STARTED WL WD DRY AB BORING COMPLETED WL RIG CME 7 FOREMAN CMG WL Initial Water Level Reading APPROVED RLD JOB # 0806

47

48 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification Classification LL PL PI Cc Cu 1 9.0ft (9 to 1 feet) NP NP NP ft (19 to 2 feet) NP NP NP ft (29 to 3 feet) NP NP NP ft ( to feet) NP NP NP ft (0 to 0 feet) NP NP NP Specimen Identification D0 D60 D D %Gravel %Sand %Silt %Clay 1 9.0ft ft ft ft ft GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

49 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification 3 9.0ft 3.0ft.0ft.0ft 7.0ft Specimen Identification 3 9.0ft 3.0ft.0ft.0ft 7.0ft Classification LL PL PI Cc Cu (9 to feet) NP NP NP ( to 0 feet) NP NP NP ( to feet) NP NP NP ( to feet) NP NP NP (0 to 7 feet) NP NP NP D0 D60 D D %Gravel %Sand %Silt %Clay GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date: 19.6

50 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification Classification LL PL PI Cc Cu 0.0ft ( 0 to feet) NP NP NP.0ft ( to feet) NP NP NP ft ( to feet) NP NP NP 0.0ft ( to 0 feet) NP NP NP ft (0 to 7 feet) Specimen Identification D0 D60 D D %Gravel %Sand %Silt %Clay 0.0ft ft ft ft ft GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

51 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification 6.0ft 6.0ft 8 0.0ft 8.0ft.0ft Specimen Identification 6.0ft 6.0ft 8 0.0ft 8.0ft.0ft D Classification ( to feet) ( to 2 feet) (0 to feet) ( to feet) ( to feet) D60 D D LL PL NP NP NP NP NP NP NP NP NP NP %Gravel %Sand GRAIN SIZE DISTRIBUTION PI Cc Cu NP NP NP NP NP %Silt %Clay Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

52 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL coarse fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification Classification LL PL PI Cc Cu 0.0ft (0 to 7 feet) NP NP NP ft ( to feet) NP NP NP ft ( to feet) NP NP NP ft (0 to feet) NP NP NP ft ( to feet) NP NP NP Specimen Identification D0 D60 D D %Gravel %Sand %Silt %Clay 0.0ft ft ft ft ft GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

53 0 U.S. SIEVE OPENING IN INCHES 2 1 1/ / 3/8 6 U.S. SIEVE NUMBERS HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL coarse fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification Classification LL PL 13.0ft ( to feet) NP NP ft ( to 0 feet) NP NP 16.0ft ( to feet) NP NP 16.0ft ( to feet) NP NP ft (9 to feet) NP NP Specimen Identification D0 D60 D D %Gravel %Sand 13.0ft ft ft ft ft GRAIN SIZE DISTRIBUTION PI Cc Cu NP NP NP NP NP %Silt %Clay Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

54 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification 17.0ft 17.0ft ft ft 0.0ft Specimen Identification 17.0ft 17.0ft ft 19.0ft ft D Classification ( to feet) ( to 38 feet) (0 to feet) ( to feet) (0 to feet) D60 D D LL PL PI Cc Cu NP NP NP NP NP NP NP NP NP NP NP NP NP NP NP %Gravel %Sand %Silt %Clay GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

55 0 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification 21.0ft 22.0ft 22.0ft 22.0ft ft Specimen Identification 21.0ft 22.0ft 22.0ft 22.0ft ft D Classification ( to 22 feet) (0.0 to feet) ( to feet) ( to feet) (0.0 to 9 feet) D60 D D LL PL PI Cc Cu NP NP NP NP NP NP NP NP NP NP NP NP NP NP NP %Gravel %Sand %Silt %Clay GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

56 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification ft ft 23.0ft 2.0ft 2.0ft Specimen Identification ft ft 23.0ft 2.0ft 2.0ft D Classification (19 to 29 feet) (29 to 39 feet) (39 to feet) ( to feet) ( to 1 feet) D60 D D LL PL PI Cc Cu NP NP NP NP NP NP NP NP NP NP NP NP NP NP NP %Gravel %Sand %Silt %Clay GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

57 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 2 1 1/ / 3/ HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES coarse GRAVEL fine coarse medium SAND fine SILT OR CLAY TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification Classification LL PL PI Cc Cu 26.0ft (0.0 to feet) NP NP NP 26.0ft ( to feet) NP NP NP 27.0ft ( to feet) NP NP NP ft ( to feet) NP NP NP ft ( to 3 feet) NP NP NP Specimen Identification D0 D60 D D %Gravel %Sand %Silt %Clay 26.0ft ft ft ft ft GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

58 0 U.S. SIEVE OPENING IN INCHES / 1/2 3/8 3 6 U.S. SIEVE NUMBERS HYDROMETER PERCENT FINER BY WEIGHT GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL coarse fine coarse medium SAND fine SILT OR CLAY Specimen Identification ft ft ft ft Classification (9 to 19 feet) (19 to 29 feet) (29 to 39 feet) (0 to 9 feet) LL NP NP NP NP PL NP NP NP NP PI NP NP NP NP Cc Cu TC_GRAIN_SIZE GPJ BORING.GDT 9/26/08 Specimen Identification D ft ft ft 9.0ft 9.. D D D %Gravel %Sand %Silt %Clay GRAIN SIZE DISTRIBUTION Project: Bearson Gravel Study Site: SEC OF WELD CO. ROADS 17 & 28 Weld County, Colorado Job #: 0806 Date:

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60 GENERAL NOTES DRILLING & SAMPLING SYMBOLS: : Split Spoon /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 - 2.2" I.D., 3" O.D., unless otherwise noted HA: Hand Auger DB: Diamond Bit Coring - ", N, B RB: Rock Bit : 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 () the last inches of the total 18-inch penetration with a 10-pound hammer falling inches is considered the Standard Penetration or N-value. For 3 O.D. ring samplers (RS) the penetration value is reported as the number of blows required to advance the sampler inches using a 10- pound hammer falling inches, reported as blows per foot, and is not considered equivalent to the Standard Penetration or Nvalue. WATER LEVEL MEASUREMENT SYMBOLS: WL: Water Level WS: While Sampling 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 CLAIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 0% of their dry weight retained on a #0 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 0% of their dry weight retained on a #0 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. (RS) Blows/Ft. FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK () Blows/Ft. Consistency (RS) Blows/Ft. () Blows/Ft. Relative Density (RS) Blows/Ft. () Blows/Ft. Consistency < Very Soft 0-6 < 3 Very Loose < < Weathered 3-3- Soft Loose Firm -9-8 Medium Stiff Medium Dense Medium Hard Stiff Dense Hard Very Stiff > 98 > 0 Very Dense > 119 > 79 Very Hard > 2 > Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Terms of Other Constituents Percent of Dry Weight Major Component of Sample GRAIN SIZE TERMINOLOGY Particle Size Trace < 1 Boulders Over in. (0mm) With 1 29 Cobbles in. to 3 in. (0mm to 7 mm) Modifier > Gravel 3 in. to # sieve (7mm to.7 mm) Sand Silt or Clay # to #0 sieve (.7mm to 0.07mm) Passing #0 Sieve (0.07mm) RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION Descriptive Terms of Other Constituents Trace With Modifiers Percent of Dry Weight Term Plasticity Index < > Non-plastic Low Medium High

61 Coarse Grained Soils More than 0% retained on No. 0 sieve UNIFIED SOIL CLAIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Group Symbol Soil Classification Group Name B Gravels Clean Gravels Cu and 1 Cc 3 E GW Well graded gravel F More than 0% of coarse Less than % fines C fraction retained on Cu < and/or 1 > Cc > 3 E GP Poorly graded gravel F No. sieve Gravels with Fines More Fines classify as ML or MH GM Silty gravel F,G, H than % fines C Fines classify as CL or CH GC Clayey gravel F,G,H Sands 0% or more of coarse fraction passes No. sieve Clean Sands Cu 6 and 1 Cc 3 E SW Well graded sand I Less than % fines D Cu < 6 and/or 1 > Cc > 3 E SP Poorly graded sand I Sands with Fines Fines classify as ML or MH SM Silty sand G,H,I More than % fines D Fines classify as CL or CH SC Clayey sand G,H,I Fine-Grained Soils 0% or more passes the No. 0 sieve Silts and Clays Liquid limit less than 0 Silts and Clays Liquid limit 0 or more inorganic PI > 7 and plots on or above A line J CL Lean clay K,L,M PI < or plots below A line J ML Silt K,L,M organic Liquid limit - oven Organic clay K,L,M,N < 0.7 OL dried Liquid limit - not Organic silt K,L,M,O dried inorganic PI plots on or above A line CH Fat clay K,L,M organic PI plots below A line MH Elastic silt K,L,M Liquid limit - oven dried Liquid limit - not dried < 0.7 OH Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat Organic clay K,L,M,P Organic silt K,L,M,Q A Based on the material passing the 3-in. (7-mm) sieve B If field sample contained cobbles or boulders, or both, add with cobbles or boulders, or both to group name. C Gravels with to % fines require dual symbols: GW-GM well graded gravel with silt, GW-GC well graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with to % fines require dual symbols: SW-SM well graded sand with silt, SW-SC well graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay 2 E (D) Cu = D 60 /D Cc = D x D60 F If soil contains 1% sand, add with sand to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. H If fines are organic, add with organic fines to group name. I If soil contains 1% gravel, add with gravel to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 1 to 29% plus No. 0, add with sand or with gravel, whichever is predominant. L If soil contains % plus No. 0 predominantly sand, add sandy to group name. M If soil contains % plus No. 0, predominantly gravel, add gravelly to group name. N PI and plots on or above A line. O PI < or plots below A line. P PI plots on or above A line. Q PI plots below A line.

62 ROCK CLAIFICATION (Based on ASTM C-29) Sedimentary Rocks Sedimentary rocks are stratified materials laid down by water or wind. The sediments may be composed of particles or pre-existing rocks derived by mechanical weathering, evaporation or by chemical or organic origin. The sediments are usually indurated by cementation or compaction. Chert Claystone Conglomerate Very fine-grained siliceous rock composed of micro-crystalline or cyrptocrystalline quartz, chalcedony or opal. Chert is various colored, porous to dense, hard and has a conchoidal to splintery fracture. Fine-grained rock composed of or derived by erosion of silts and clays or any rock containing clay. Soft massive and may contain carbonate minerals. Rock consisting of a considerable amount of rounded gravel, sand and cobbles with or without interstitial or cementing material. The cementing or interstitial material may be quartz, opal, calcite, dolomite, clay, iron oxides or other materials. Dolomite A fine-grained carbonate rock consisting of the mineral dolomite [CaMg(CO 3 ) 2 ]. May contain noncarbonate impurities such as quartz, chert, clay minerals, organic matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). Limestone Sandstone Shale Siltstone A fine-grained carbonate rock consisting of the mineral calcite (CaCO 3 ). May contain noncarbonate impurities such as quartz, chert, clay minerals, organic matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). Rock consisting of particles of sand with or without interstitial and cementing materials. The cementing or interstitial material may be quartz, opal, calcite, dolomite, clay, iron oxides or other material. Fine-grained rock composed of or derived by erosion of silts and clays or any rock containing clay. Shale is hard, platy, of fissile may be gray, black, reddish or green and may contain some carbonate minerals (calcareous shale). Fine grained rock composed of or derived by erosion of silts or rock containing silt. Siltstones consist predominantly of silt sized particles (0.062 to mm in diameter) and are intermediate rocks between claystones and sandstones and may contain carbonate minerals.

63 LABORATORY TEST SIGNIFICANCE AND PURPOSE TEST SIGNIFICANCE PURPOSE California Bearing Ratio Consolidation Used to evaluate the potential strength of subgrade soil, subbase, and base course material, including recycled materials for use in road and airfield pavements. Used to develop an estimate of both the rate and amount of both differential and total settlement of a structure. Pavement Thickness Design Foundation Design Direct Shear Dry Density Expansion Gradation Liquid & Plastic Limit, Plasticity Index Permeability ph Resistivity R-Value Soluble Sulphate Unconfined Compression Water Content Used to determine the consolidated drained shear strength of soil or rock. Used to determine the in-place density of natural, inorganic, fine-grained soils. Used to measure the expansive potential of fine-grained soil and to provide a basis for swell potential classification. Used for the quantitative determination of the distribution of particle sizes in soil. Used as an integral part of engineering classification systems to characterize the fine-grained fraction of soils, and to specify the fine-grained fraction of construction materials. Used to determine the capacity of soil or rock to conduct a liquid or gas. Used to determine the degree of acidity or alkalinity of a soil. Used to indicate the relative ability of a soil medium to carry electrical currents. Used to evaluate the potential strength of subgrade soil, subbase, and base course material, including recycled materials for use in road and airfield pavements. Used to determine the quantitative amount of soluble sulfates within a soil mass. To obtain the approximate compressive strength of soils that possess sufficient cohesion to permit testing in the unconfined state. Used to determine the quantitative amount of water in a soil mass. Bearing Capacity, Foundation Design, and Slope Stability Index Property Soil Behavior Foundation and Slab Design Soil Classification Soil Classification Groundwater Flow Analysis Corrosion Potential Corrosion Potential Pavement Thickness Design Corrosion Potential Bearing Capacity Analysis for Foundations Index Property Soil Behavior

64 REPORT TERMINOLOGY (Based on ASTM D63) Allowable Soil Bearing Capacity Alluvium Aggregate Base Course Backfill Bedrock Bench Caisson (Drilled Pier or Shaft) Coefficient of Friction Colluvium Compaction Concrete Slab-on- Grade Differential Movement Earth Pressure The recommended maximum contact stress developed at the interface of the foundation element and the supporting material. Soil, the constituents of which have been transported in suspension by flowing water and subsequently deposited by sedimentation. A layer of specified material placed on a subgrade or subbase usually beneath slabs or pavements. A specified material placed and compacted in a confined area. A natural aggregate of mineral grains connected by strong and permanent cohesive forces. Usually requires drilling, wedging, blasting or other methods of extraordinary force for excavation. A horizontal surface in a sloped deposit. A concrete foundation element cast in a circular excavation which may have an enlarged base. Sometimes referred to as a cast-in-place pier or drilled shaft. A constant proportionality factor relating normal stress and the corresponding shear stress at which sliding starts between the two surfaces. Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of a slope or cliff. The densification of a soil by means of mechanical manipulation A concrete surface layer cast directly upon a base, subbase or subgrade, and typically used as a floor system. Unequal settlement or heave between, or within foundation elements of structure. The pressure exerted by soil on any boundary such as a foundation wall. ESAL Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000 pound axle loads). Engineered Fill Equivalent Fluid Existing Fill (or Man-Made Fill) Existing Grade Specified material placed and compacted to specified density and/or moisture conditions under observations of a representative of a geotechnical engineer. A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral support presumed to be equivalent to that produced by the actual soil. This simplified approach is valid only when deformation conditions are such that the pressure increases linearly with depth and the wall friction is neglected. Materials deposited throughout the action of man prior to exploration of the site. The ground surface at the time of field exploration.

65 REPORT TERMINOLOGY (Based on ASTM D63) Expansive Potential Finished Grade Footing Foundation Frost Depth Grade Beam Groundwater Heave Lithologic Native Grade Native Soil Optimum Moisture Content Perched Water Scarify Settlement Skin Friction (Side Shear) Soil (Earth) Strain Stress Strip Subbase Subgrade The potential of a soil to expand (increase in volume) due to absorption of moisture. The final grade created as a part of the project. A portion of the foundation of a structure that transmits loads directly to the soil. The lower part of a structure that transmits the loads to the soil or bedrock. The depth at which the ground becomes frozen during the winter season. A foundation element or wall, typically constructed of reinforced concrete, used to span between other foundation elements such as drilled piers. Subsurface water found in the zone of saturation of soils or within fractures in bedrock. Upward movement. The characteristics which describe the composition and texture of soil and rock by observation. The naturally occurring ground surface. Naturally occurring on-site soil, sometimes referred to as natural soil. The water content at which a soil can be compacted to a maximum dry unit weight by a given compactive effort. Groundwater, usually of limited area maintained above a normal water elevation by the presence of an intervening relatively impervious continuous stratum. To mechanically loosen soil or break down existing soil structure. Downward movement. The frictional resistance developed between soil and an element of the structure such as a drilled pier. Sediments or other unconsolidated accumulations of solid particles produced by the physical and chemical disintegration of rocks, and which may or may not contain organic matter. The change in length per unit of length in a given direction. The force per unit area acting within a soil mass. To remove from present location. A layer of specified material in a pavement system between the subgrade and base course. The soil prepared and compacted to support a structure, slab or pavement system.

66 ATTACHMENT B PC-STABL Results

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