Geotechnical Engineering Report

Transcription

1 Geotechnical Engineering Report Shaw AFB East Gate Entrance Control Facility Amendment Sumter, South Carolina September 13, 2010 Terracon Project No A Prepared for: TranSystems North Charleston, South Carolina Prepared by: Terracon Consultants, Inc. Columbia, South Carolina

2 September 13, 2010 TranSystems 4390 Belle Oaks Drive, Suite 220 North Charleston, SC Attn: Re: Mr. John Collins Geotechnical Engineering Report Shaw AFB East Gate Entrance Control Facility Amendment Sumter, South Carolina Terracon Project No A Dear Mr. Collins: Terracon Consultants, Inc. (Terracon) has completed the geotechnical engineering services for the above referenced project. This study was performed in general accordance with our Proposal No. P , dated June 23, The purpose of this exploration was to obtain information on the subsurface conditions at the proposed project site, perform laboratory testing on soil samples obtained from the site and provide our client with a summary of the field testing, boring data, laboratory test data and site description. We appreciate the opportunity to be of service to you on this project. Materials testing services are provided by Terracon. We would be pleased to discuss these services with you. If you have any questions concerning this report, or if we may be of further service, please contact us. Sincerely, Terracon Consultants, Inc. Ahmed Zein, Ph.D., P.E. Project Engineer Phillip A. Morrison, P.E. Geotechnical Department Manager SC Registration No Attachments 3xc: Client 1xc: File Terracon Consultants, Inc. 521 Clemson Road Columbia, South Carolina P [803] F [803] terracon.com

3 TABLE OF CONTENTS Page 1.0 INTRODUCTION SITE LOCATION AND DESCRIPTION SUBSURFACE CONDITIONS Geology Typical Subsurface Profile Groundwater Conditions LABORATORY TESTING GENERAL COMMENTS... 3 APPENDIX A Field Exploration Site Location Map Boring Location Plan Boring Logs DCP Data Sheet Field Testing Description APPENDIX B Laboratory Test Data Laboratory Testing Description Laboratory Data Sheets Summary of Laboratory Test Results APPENDIX C Supporting Documents General Notes Unified Soil Classification System

4 REPORT OF GEOTECHNICAL EXPLORATION SHAW AFB EAST GATE ENTRANCE CONTROL FACILITY AMENDMENT SUMTER, SOUTH CAROLINA 1.0 INTRODUCTION Terracon Project No A September 13, 2010 Our geotechnical engineering scope of work for this project included the advancement of three soil test borings to a depth of 10 feet below existing site grades, performance of one Dynamic Cone Penetration (DCP) test in an existing paved area to a depth of 3 feet below the pavement surface and performance of laboratory testing on select soil samples. At the request of our client, our scope of work did not include providing engineering recommendations for the planned construction. Logs of the borings and other field tests along with a Site Location Map and a Boring Location Plan are included in Appendix A of this report. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included in Appendix B of this report. Descriptions of the field exploration and laboratory testing are included in their respective appendices. Terracon had previously prepared the geotechnical engineering report for this project (Terracon Report No , dated April 27, 2010). Our previous geotechnical engineering scope of work included drilling of six soil test borings, performance of six DCP tests and performance of geophysical (ReMi) testing. The purpose of the previous exploration was to obtain information on the subsurface conditions at the proposed project site and, based on this information, provide recommendations regarding the design and construction of foundations and floor slabs for the new gatehouse and overwatch building. The current study is considered an addendum to that report. As such, all limitations and recommendations associated with that report apply to this document. 2.0 SITE LOCATION AND DESCRIPTION ITEM Location Existing development Current ground cover DESCRIPTION The areas north and east of the existing contractor s entrance guard house within the southeast extreme of Shaw AFB near Sumter, South Carolina. The project area is primarily undeveloped. Asphalt paving and grass. Reliable Responsive Convenient Innovative 1

5 Geotechnical Engineering Report East Gate Entrance Control Facility Amendment Sumter, South Carolina September 13, 2010 Terracon Project No A ITEM Existing topography Existing Utilities DESCRIPTION In general, the site grades slightly slope up toward the north. Based on the provided topographic site plan, the site grades range from Elevation 206 feet on the south side (vicinity of Boring CBR-7) to Elevation 209 feet on the north side of the site (vicinity of Boring CBR-9). No underground utilities were marked at the site by the public utility locators. 3.0 SUBSURFACE CONDITIONS 3.1 Geology The site is located in the upper Coastal Plain physiographic province of South Carolina. The Coastal Plain is a wedge-shaped cross-section of water and wind deposited soil. Its thickness ranges from a featheredge at the surface contact of the Piedmont (Fall Line) to several thousand feet at the present day coastline. The sediments range in age from the Cretaceous and Tertiary periods at the contact with the bedrock to the recent period at the present coastline. The sediments include clays, silts, sands, and gravels, as well as organics. 3.2 Typical Subsurface Profile Specific conditions encountered at each boring location are indicated on the individual boring logs. Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in-situ, the transition between materials may be gradual. Details for each of the borings can be found on the boring logs included in Appendix A of this report. Based on the results of the borings, subsurface conditions on the project site can be generalized as follows: Description Surface Treatments Approximate Depth to Bottom of Stratum (feet) 3 inches / 6 inches in Boring CBR-9 1 to 3 inches in Borings CBR-7 and CBR-8 Stratum 1 10 Material Encountered Consistency/Density Asphalt / Stone Base - Topsoil - Coastal Plain sand, clayey sand and silty sand Loose to medium dense One DCP test was performed to a depth of 3 feet below the pavement surface in Boring CBR-9. Based on the test results, the subsurface soils at this location have CBR values ranging from 22 to 100 percent. We note that these values are higher than the laboratory CBR values (see Section 4). These values were measure in dry conditions, whereas laboratory CBR testing is performed on soaked soils. Reliable Responsive Convenient Innovative 2

6 Geotechnical Engineering Report East Gate Entrance Control Facility Amendment Sumter, South Carolina September 13, 2010 Terracon Project No A 3.3 Groundwater Conditions Groundwater was not encountered by the borings during the field exploration. These observations represent conditions at the time of the field exploration and may not be indicative of other times, or at other locations. Groundwater conditions can change with varying seasonal and weather conditions, and other factors. The possibility of groundwater fluctuations should be considered when developing design and construction plans for the project. 4.0 LABORATORY TESTING The samples were classified in the laboratory based on visual observation, texture and plasticity. The soil descriptions indicated on the boring logs are in accordance with the enclosed the Unified Soil Classification System (USCS). Our laboratory testing program consisted of performing water content, mechanical gradations and fines content (percent of silt and clay) tests on selected soil samples. Results of these tests are provided on the boring logs and the Summary of Laboratory Results found in Appendix B. Two (2) California Bearing Ratio (CBR) tests were performed on bulk samples obtained from borings drilled in grassed areas (Borings CBR-7 and CBR-8). The samples were obtained from below the topsoil layer to a depth of about 5 feet below the ground surface. The test results for the standard Proctor testing and the CBR test results (compacted to 100 percent of the standard Proctor value are summarized in the table below. BORING STANDARD PROCTOR MAXIMUM DRY UNIT WEIGHT, PCF STANDARD PROCTOR OPTIMUM WATER CONTENT, % CBR VALUE IN. 0.2 IN. CBR CBR CBRs compacted to 100 percent of the standard Proctor maximum dry unit weight. 5.0 GENERAL COMMENTS 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 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. Reliable Responsive Convenient Innovative 3

7 Geotechnical Engineering Report East Gate Entrance Control Facility Amendment Sumter, South Carolina September 13, 2010 Terracon Project No A 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. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, 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. Reliable Responsive Convenient Innovative 4

8 APPENDIX A FIELD EXPLORATION

9 SITE Project Mngr. ASZ Scale: PTK Checked B y: ASZ Approved By: PAM Project No A Scale: N.T.S. File Name: Fig 1 Date: September CLEMSON ROAD COLUMBIA, SC PH. (803) FAX. (803) SITE LOCATION MAP EAST GATE ENTRANCE CONTROL FACILITY AMENDMENT SHAW AIR FORCE BASE Sumter, South Carolina FIG No. 1

10

11 CLIENT SITE TRANSYSTEMS SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA LOG OF BORING NO. CBR-7 PROJECT EAST GATE ECF AMENDMENT SAMPLES TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION Approx. Surface Elev.: 206 ft 0.3 TOPSOIL, (3 inches) FINE SAND, trace silt, brown to light brown, loose (Coastal Plain) DEPTH, ft. USCS SYMBOL NUMBER TYPE HS RECOVERY, in. SPT - N BLOWS / ft. WATER CONTENT, % SP 1 SS 9 4 DRY UNIT WT pcf UNCONFINED STRENGTH, psf 2% Fines HS 2 SS 5 5 HS 3 SS 8 8 SILTY FINE SAND, light brown, medium dense HS SS BORING TERMINATED BORING TERMINATED BOREHOLE_ A.GPJ GAGE TERRACON.GDT 9/13/10 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft WL WL WL DRY BORING STARTED BORING COMPLETED RIG CME-55 FOREMAN HW APPROVED FRM JOB # A

12 CLIENT SITE TRANSYSTEMS SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA LOG OF BORING NO. CBR-8 PROJECT EAST GATE ECF AMENDMENT SAMPLES TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION Approx. Surface Elev.: 208 ft 0.1 TOPSOIL, (1 inch) SILTY FINE SAND, brown, loose (Coastal Plain) 208 DEPTH, ft. USCS SYMBOL NUMBER 1 TYPE HS SS RECOVERY, in. SPT - N BLOWS / ft. 9 WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf 3 FINE SAND, trace silt, light brown, loose 205 HS SP 2 SS % Fines 5 HS 3 SS 4 8 CLAYEY FINE SAND, light tannish gray, loose HS SS 7 10 BORING TERMINATED BORING TERMINATED BOREHOLE_ A.GPJ GAGE TERRACON.GDT 9/13/10 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft WL WL WL DRY BORING STARTED BORING COMPLETED RIG CME-55 FOREMAN HW APPROVED FRM JOB # A

13 CLIENT SITE TRANSYSTEMS SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA LOG OF BORING NO. CBR-9 PROJECT EAST GATE ECF AMENDMENT SAMPLES TESTS Page 1 of 1 GRAPHIC LOG DESCRIPTION Approx. Surface Elev.: 209 ft 0.3 ASPHALT, (3 inches) 0.8 STONE BASE, (6 inches) SILTY FINE SAND, brown, medium dense (Coastal Plain) DEPTH, ft. USCS SYMBOL NUMBER 1 TYPE HS SS RECOVERY, in. SPT - N BLOWS / ft. 12 WATER CONTENT, % DRY UNIT WT pcf UNCONFINED STRENGTH, psf 3 FINE SAND, trace silt, light brown, loose HS SS FINE SAND, with clay, tan to light tannish gray, loose to medium dense SP SM 3 HS SS % Fines HS 4 SS BORING TERMINATED BORING TERMINATED BOREHOLE_ A.GPJ GAGE TERRACON.GDT 9/13/10 The stratification lines represent the approximate boundary lines between soil and rock types: in-situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft WL WL WL DRY BORING STARTED BORING COMPLETED RIG CME-55 FOREMAN HW APPROVED FRM JOB # A

14 DCP Data Sheet 1 Project Name: Location Date: Test No. Shaw Air Force Base - East Gate Entrance Control Facility Amendment Sumter, South Carolina 8/13/2010 CBR-9 Blows Scale Reading (mm) Cumulative Penetration (mm) Cumulative Penetration (feet) Penetration Between Readings (mm) Penetration Per Blow (mm) Hammer Factor DCP Index (mm/blow) CBR % Set Notes: 1 The instrument used for this test is typically used to assess the material properties down to a depth of 1000 mm (39 in.) below the surface. Below this depth, the mass and the inertia of the device will change and skin friction along drive rod extensions will occur. As such, the actual CBR values below a depth of 39 in. may be slightly different than reported in this table.

15 Geotechnical Engineering Report East Gate Entrance Control Facility Amendment Sumter, South Carolina September 13, 2010 Terracon Project No A Field Exploration Description Three soil test borings were drilled at the site on August 13, The borings were drilled to a depth of 10 feet below the ground surface at the approximate locations shown on the attached Boring Location Plan. Our personnel located the borings by pacing distances and approximating right angles from the existing site features shown on the provided site plans. The ground surface elevations at the boring locations were interpolated from the contour lines shown on the provided site plans and are shown on the Boring Logs. The boring locations shown on the Boring Location Plans and the ground elevations shown on the Boring Logs are approximate and should be considered accurate only to the degree implied by the method of location. The boreholes were advanced with an ATV-mounted CME-550 drill rig using hollow stem augers. In each boring, standard penetration tests were performed with a manual gravity hammer. The borings were sampled using split-spoons at depth intervals of 2-½ feet. At the completion of the drilling activities, the boreholes were checked for the presence of groundwater at the time of drilling and then were backfilled with auger cuttings at the completion of field exploration. The borings drilled in paved areas were grouted with a cement slurry mix and their surfaces patched with a cold patch asphalt mix after drilling. Representative portions of the split-spoon samples recovered in the borings were placed in glass jars and returned to our laboratory where our engineer visually reviewed and classified them. The purposes of this review were to check the drillers field classifications and visually estimate the soils relative constituents (sand, clay, etc.). The soil types and standard penetration data are shown on the Boring Logs. These records represent our interpretation of the field conditions based on the driller s field logs and our engineer s review of the split-spoon samples. The lines designating the interfaces between various strata represent approximate boundaries only, as transitions between materials may be gradual. Our exploration services include storing the collected soil samples and making them available for inspection for 60 days from the report date. The samples will then be discarded unless requested otherwise. Dynamic cone penetration testing (ASTM D6951) was performed at the boring drilled in pavement (Boring CBR-9). The test was performed by driving the DCP tip into soil by lifting a 10.1-pound sliding hammer to the handle then releasing it. The penetration values represent the number of blows required to advance the penetrometer in 2-inch increments and are an indication of the consistency or density of the soil. The collected data was then used to estimate the in-situ CBR of the subsurface soils. The test was conducted to a depth of about 3 feet below the pavement. The test results are shown in the DCP data sheets included in this appendix.

16 APPENDIX B LABORATORY TEST DATA

17 Geotechnical Engineering Report East Gate Entrance Control Facility Amendment Sumter, South Carolina September 13, 2010 Terracon Project No A Laboratory Testing Description Samples retrieved during the field exploration were taken to the laboratory for further observation by the project geotechnical engineer and were classified in accordance with the Unified Soil Classification System (USCS) described in Appendix C. At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. Laboratory tests were conducted on selected soil samples and the test results are presented in this appendix. Laboratory tests were performed in general accordance with the applicable ASTM, local or other accepted standards. Selected soil samples obtained from the site were tested for the following engineering properties: In-situ Water Content Standard Proctor CBR Sieve Analysis Fines Content

18 CALIFORNIA BEARING RATIO ( CBR ) TEST REPORT ( ASTM D1883 ) JOB NAME : Shaw AFB - East Gate ECF Amendment DATE : 8/20/10 JOB NO. : A SAMPLE NO. : - BORING / PIT NO. : CBR-7 LIQUID LIMIT, % : n/a DEPTH / ELEV.: 0-5 ft PLASTICITY INDEX, % : n/a SOIL DESCRIPITION : Light brown tan fine SAND FINES, % : n/a PISTON STRESS, PSI Corrected Test Results: At 0.1 inches CBR = 11.0 At 0.2 inches CBR = 16.2 Swell 0.0% Sample Compaction: 100% Standard Proctor at 10.3 percent moisture content Standard Proctor Results: Dry Density of pcf at 10.3 percent moisture content PISTON PENETRATION, INCHES 521 Clemson Road Performed by: FPM Columbia, SC Reviewed by: ASZ

19 CALIFORNIA BEARING RATIO ( CBR ) TEST REPORT ( ASTM D1883 ) JOB NAME : Shaw AFB - East Gate ECF Amendment DATE : 8/24/10 JOB NO. : A SAMPLE NO. : - BORING / PIT NO. : CBR-8 LIQUID LIMIT, % : n/a DEPTH / ELEV.: 0-5 ft PLASTICITY INDEX, % : n/a SOIL DESCRIPITION : Light tan brown fine to medium SAND FINES, % : n/a PISTON STRESS, PSI Corrected Test Results: At 0.1 inches CBR = 18.8 At 0.2 inches CBR = 25.1 Swell 0.0% Sample Compaction: 100% Standard Proctor at 9.5 percent moisture content Standard Proctor Results: Dry Density of pcf at 9.5 percent moisture content PISTON PENETRATION, INCHES 521 Clemson Road Performed by: FPM Columbia, SC Reviewed by: ASZ

20 Source of Material Description of Material Test Method CBR-7 0.0ft Light brownish tan FINE SAND ASTMD698 Method A 115 DRY UNIT WEIGHT, pcf TEST RESULTS Maximum (optimum) Dry Unit Weight Optimum Water Content ATTERBERG LIMITS LL PL PI Curves of 100% Saturation for Specific Gravity Equal to: PCF % 85 TC_COMPACTION A.GPJ GAGE TERRACON.GDT 9/13/ WATER CONTENT, % MOISTURE-DENSITY RELATIONSHIP Project: EAST GATE ECF AMENDMENT Site: SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA Job #: A Date:

21 Source of Material Description of Material Test Method CBR-8 0.0ft Light tannish brown FINE SAND ASTMD698 Method A 115 DRY UNIT WEIGHT, pcf TEST RESULTS Maximum (optimum) Dry Unit Weight Optimum Water Content ATTERBERG LIMITS LL PL PI Curves of 100% Saturation for Specific Gravity Equal to: PCF % 85 TC_COMPACTION A.GPJ GAGE TERRACON.GDT 9/13/ WATER CONTENT, % MOISTURE-DENSITY RELATIONSHIP Project: EAST GATE ECF AMENDMENT Site: SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA Job #: A Date:

22 100 U.S. SIEVE OPENING IN INCHES / /4 3/ 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 CBR-7 1.0ft Classification LL PL PI Cc 0.97 Cu 3.60 TC_GRAIN_SIZE A.GPJ GAGE TERRACON.GDT 9/13/10 Specimen Identification CBR-7 1.0ft D100 D60 D30 D10 %Gravel %Sand %Silt GRAIN SIZE DISTRIBUTION Project: EAST GATE ECF AMENDMENT Site: SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA Job #: A Date: %Clay

23 100 U.S. SIEVE OPENING IN INCHES / /4 3/ 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 CBR-8 3.5ft Classification LL PL PI Cc 0.94 Cu 3.21 TC_GRAIN_SIZE A.GPJ GAGE TERRACON.GDT 9/13/10 Specimen Identification CBR-8 3.5ft D100 D60 D30 D10 %Gravel %Sand %Silt GRAIN SIZE DISTRIBUTION Project: EAST GATE ECF AMENDMENT Site: SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA Job #: A Date: %Clay

24 100 U.S. SIEVE OPENING IN INCHES / /4 3/ 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 CBR-9 6.0ft Classification LL PL PI Cc Cu TC_GRAIN_SIZE A.GPJ GAGE TERRACON.GDT 9/13/10 Specimen Identification CBR-9 6.0ft D100 D60 D30 D10 %Gravel %Sand %Silt GRAIN SIZE DISTRIBUTION Project: EAST GATE ECF AMENDMENT Site: SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA Job #: A Date: %Clay

25 Borehole Depth ft Liquid Limit Plastic Limit Plasticity Index Maximum Size (mm) %<#200 Sieve Water Content (%) CBR SP 4 CBR SP 3 CBR Dry Unit Weight (pcf) USCS Classification Saturation (%) Sheet 1 of 1 Void Ratio TC_LAB_SUMMARY A.GPJ GAGE TERRACON.GDT 9/13/10 SUMMARY OF LABORATORY RESULTS Project: EAST GATE ECF AMENDMENT Site: SHAW AIR FORCE BASE SUMTER, SOUTH CAROLINA Job #: A Date:

26 APPENDIX C SUPPORTING DOCUMENTS

27 GENERAL NOTES DRILLING & SAMPLING SYMBOLS: SS: 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 " 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 penetration 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 Unconfined Compressive Strength, Qu, psf Standard Penetration or N-value (SS) Blows/Ft. RELATIVE DENSITY OF COARSE-GRAINED SOILS Standard Penetration or N-value (SS) Blows/Ft. Consistency Relative Density < 500 <2 Very Soft 0 3 Very Loose 500 1, Soft 4 9 Loose 1,001 2,000 2, Medium Stiff Medium Dense 2,001 4,000 4, Stiff Dense 4,001 8, Very Stiff 50+ Very Dense 8, Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Term(s) of other constituents Percent of Dry Weight Major Component of Sample GRAIN SIZE TERMINOLOGY Particle Size Trace < 15 Boulders Over 12 in. (300mm) With Cobbles 12 in. to 3 in. (300mm to 75 mm) Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm) RELATIVE PROPORTIONS OF FINES Sand Silt or Clay #4 to #200 sieve (4.75mm to 0.075mm) Passing #200 Sieve (0.075mm) Descriptive Term(s) of other constituents Trace With Modifiers Percent of Dry Weight < > 12 PLASTICITY DESCRIPTION Term Non-plastic Low Medium High Plasticity Index

28 Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Coarse Grained Soils More than 50% retained on No. 200 sieve Fine-Grained Soils Silts and Clays 50% or more passes the Liquid limit less than 50 No. 200 sieve UNIFIED SOIL CLASSIFICATION SYSTEM Soil Classification Group Symbol Group Name B Gravels Clean Gravels Cu 4 and 1 Cc 3 E GW Well-graded gravel F More than 50% of coarse Less than 5% fines C fraction retained on Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F No. 4 sieve Gravels with Fines More Fines classify as ML or MH GM Silty gravel F,G, H than 12% fines C Fines classify as CL or CH GC Clayey gravel F,G,H Sands Clean Sands Cu 6 and 1 Cc 3 E SW Well-graded sand I 50% or more of coarse Less than 5% fines D fraction passes Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I No. 4 sieve Sands with Fines Fines classify as ML or MH SM Silty sand G,H,I More than 12% fines D Fines Classify as CL or CH SC Clayey sand G,H,I Silts and Clays Liquid limit 50 or more Inorganic PI 7 and plots on or above A line J CL Lean clay K,L,M PI 4 or plots below A line J ML Silt K,L,M Organic Liquid limit - oven dried 0.75 OL Organic clay K,L,M,N Liquid limit - not dried Organic silt K,L,M,O Inorganic PI plots on or above A line CH Fat clay K,L,M PI lots below A line MH Elastic Silt K,L,M Organic Liquid limit - oven dried 0.75 OH Organic clay K,L,M,P Liquid limit - not dried Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat Organic silt K,L,M,Q A Based on the material passing the 3-in. (75-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 5 to 12% 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 5 to 12% 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 E (D30) Cu = D 60/D 10 Cc = D10 x D 2 60 F If soil contains 15% 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 15% 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 15 to 29% plus No. 200, add with sand or with gravel, whichever is predominant. L If soil contains 30% plus No. 200 predominantly sand, add sandy to group name. M If soil contains 30% plus No. 200, predominantly gravel, add gravelly to group name. N PI 4 and plots on or above A line. O PI 4 or plots below A line. P PI plots on or above A line. Q PI plots below A line. Form 111 6/98