Preliminary Geotechnical Engineering Study DCPL Capitol View Branch Library Washington, D.C. HCEA Job No A. Prepared for:

Transcription

1 Preliminary Geotechnical Engineering Study DCPL Capitol View Branch Library Washington, D.C. HCEA Job No A Prepared for: Smoot Construction Company 5335 Wisconsin Avenue, NW Washington, DC HLLS-CARNES ENGNEERNG ASSOCATES, NC.

2 February 4, 2015 Smoot Construction Company 5335 Wisconsin Avenue, NW Washington, DC Attention: Mr. Stuart M. Dziura Re: Gentlemen: Preliminary Geotechnical Engineering Study DCPL Capitol View Branch Library Washington, D.C. HCEA Job No A Guilford Road, Suite A Post Office Box 241 Annapolis Junction, MD Baltimore DC Metro Fax Hillis-Carnes Engineering Associates, nc. (HCEA) is pleased to submit this report concerning the preliminary subsurface exploration and subsequent preliminary geotechnical evaluation for the proposed library construction that is to be located in Washington, D.C. ENGNEERNG ASSOCATES, NC. We wish to advise you that the boring samples will be stored at our Annapolis Junction, Maryland office for a period of 30 days from the date of this letter. Should you wish the samples to be stored for a longer period of time or to be delivered to you or another party, please advise us in writing prior to the end of the 30-day period. Otherwise, the samples will be discarded at the end of the 30-day storage period. HCEA appreciates having had the opportunity to provide the geotechnical consultation for this project, and we will remain available for further consultation during the various design stages. n order to provide complete professional services, we strongly recommend that inspection of the geotechnical aspects of construction be conducted by HCEA. This will help to verify that the construction operations are performed in accordance with the design recommendations of this report and the overall project plans and specifications. Should you have any questions concerning the contents of this report, or require additional consultation, design, inspection, or testing services, please contact our Office. Very truly yours, HLLS-CARNES ENGNEERNG ASSOCATES, NC. Michael P. Johnson, P.E. Timothy B. Hill, P.E. HLLS-CARNES ENGNEERNG ASSOCATES, NC.

3 TABLE OF CONTENTS LETTER OF TRANSMTTAL... i 1.0 PURPOSE AND SCOPE PROJECT CHARACTERSTCS FELD EXPLORATON SUBSURFACE CONDTONS Man-Placed Fill Materials Natural Materials Groundwater PRELMNARY EVALUATONS AND RECOMMENDATONS General Site Preparation Fill Selection, Placement and Compaction Foundation Evaluations Ground-Supported Slabs Groundwater and Drainage REMARKS... 7 APPENDX... 9 HLLS-CARNES ENGNEERNG ASSOCATES, NC.

4 PRELMNARY GEOTECHNCAL ENGNEERNG STUDY DCPL CAPTOL VEW BRANCH LBRARY WASHNGTON, D.C. HCEA JOB NO A 1.0 PURPOSE AND SCOPE The purpose of this study was to preliminarily determine the general subsurface conditions at the boring locations and to preliminarily evaluate those conditions with respect to concept and design of foundation systems and floor slabs for the proposed construction. The preliminary evaluations and recommendations presented in this report were developed from an analysis of project characteristics and an interpretation of the general subsurface conditions at the site based on the boring information. The stratification lines indicated on the boring logs represent the approximate boundaries between soil types. n-situ, however, the transitions may be gradual. Such variations can best be evaluated during construction and, if necessary, any minor design changes can be made at that time. An evaluation of the site with respect to potential construction problems and recommendations dealing with the earthwork and inspection during construction are also included. The inspection is considered necessary to verify the subsurface conditions and to verify that the soils-related construction phases are performed properly. The Appendix contains a summary of the field work on which this report is based. 2.0 PROJECT CHARACTERSTCS The project site is located at 5001 Central Avenue, SE in Washington D.C. as shown on the Project Location Map (Figure 1) in the Appendix. Based on information provided by the Client, we understand that the proposed construction at the site is to include is to include a new library building. The site is currently occupied by an existing library structure that is to be removed prior to the initiation of new construction. Additional details concerning the proposed construction were not available at the time that this report was being prepared. Should any of the project characteristics differ from those outlined above, then this office should be contacted for a reevaluation of the site. HLLS-CARNES ENGNEERNG ASSOCATES, NC.

5 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study 3.0 FELD EXPLORATON n order to determine the general foundation soil types and to develop preliminary design parameters, five Standard Penetration Test (SPT) soil borings were drilled to depths of 45 ft below existing site grades in accessible locations at the site. We understand that additional borings are to be drilled once the existing structure is demolished and removed to confirm the subsurface conditions in currently inaccessible areas of the site. The boring locations were located in the field by HCEA by estimation from existing site features. Therefore, the boring locations shown on the Boring Location Plan (Figure 2) in the Appendix should be considered approximate. The borings were advanced with hollow-stem augers and the subsurface soils were sampled at 2.5 ft and 5.0 ft intervals. Samples were taken by driving a 1-3/8 inch.d. (2-inch O.D.) split-spoon sampler in accordance with ASTM D-1586 specifications. The sampler was first seated 6 inches to penetrate any loose cuttings and then was driven an additional foot with blows of a 140 pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot is designated as the "Penetration Resistance" or "N" value. The penetration resistance, when properly evaluated, is an index to the soil strength and compression characteristics. Representative portions of each soil sample were placed in glass jars and transported to HCEA's laboratory. n the laboratory, the samples were visually examined by the Geotechnical Engineer to verify the driller's field classifications. The samples were visually classified in general accordance with the Unified Soil Classification System and the field classifications were revised where necessary. The Unified Soil Classification Symbols appear on the Boring Logs and the system nomenclature is briefly described in the Appendix. 4.0 SUBSURFACE CONDTONS Details of the subsurface conditions encountered at the site are shown on the Records of Soil Exploration. A brief description of the subsurface conditions and pertinent engineering characteristics of the soils are given below. Strata divisions shown on the Records of Soil Exploration have been estimated based on visual examinations of the recovered boring samples. n the field, strata changes could occur gradually and/or at slightly different levels than indicated. Also, groundwater conditions indicated on the Records of Soil Exploration are those observed during the period of the subsurface exploration. Fluctuations in groundwater levels could occur seasonally and might also be influenced by changes in grading, runoff and infiltration rates, and other influencing factors. HLLS-CARNES ENGNEERNG ASSOCATES, NC. 2

6 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study Generalized subsurface conditions based on the results of the borings are discussed below: 4.1 Man-Placed Fill Materials Materials specifically identified as man-placed fill materials or possible manplaced fill materials were encountered at the following locations in the borings: Approximate Depth Boring of Fill Material (ft) B B B B B Since the size of the samples obtained is relatively small in comparison to the areal extent of the site and since the fill materials could be of similar composition to the natural soils encountered at the site, it is often difficult to determine the presence and composition of fill materials from the SPT samples. t should be anticipated that man-placed fill materials may be encountered at other locations and to different depths across the site due to the previous construction that has occurred on and around the project site. 4.2 Natural Materials The natural soils encountered at the site were visually classified in general accordance with the Unified Soil Classification System as silty sand (SM) and silty or sandy clay (CL or CH). "N" values from the Standard Penetration Test (SPT) borings typically indicated relative densities in the dense to very dense range for the more granular natural materials encountered. The more fine-grained materials typically exhibited consistencies in the very stiff to hard range. 4.3 Groundwater Groundwater levels were monitored in the open boreholes. The shallowest groundwater encountered in the borings was located at a depth of ft below existing site grades in the caved borehole at the location of Boring B-5. Water that appeared to be perched within the existing fill materials was encountered at a depth of 8.5+ ft in Boring B-4 and at a depth of 5.5+ ft in Boring B-5. HLLS-CARNES ENGNEERNG ASSOCATES, NC. 3

7 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study A more accurate determination of the hydrostatic water table would require the installation of perforated pipes or piezometers which could be monitored over an extended period of time. The actual level of the hydrostatic water table and the amount and level of perched water should be anticipated to fluctuate throughout the year, depending on variations in precipitation, surface run-off, infiltration, site topography, and drainage. t should also be anticipated that perched water will be encountered in pockets within the fill materials or at the interface of fill materials and natural soils. 5.0 PRELMNARY EVALUATONS AND RECOMMENDATONS Our findings indicate that the site can be developed for the proposed structure utilizing conventional spread footings and ground-supported slab construction. The presence of relatively soft and loose existing fill/possible fill materials to estimated depths of 17+ ft to ft below existing site grades will have a significant impact on construction operations. Footings should not be constructed on or over any existing fill materials. t is recommended that the proposed structure be supported on a deep foundation system consisting of either augered, cast-in-place concrete piles or drilled shafts. Alternatively, it may be possible to utilize alternative subgrade modification techniques (such as rammed-aggregate piers) in order to provide a shallow foundation alternative for the structure. The following preliminary recommendations have been developed on the basis of the previously described project characteristics and subsurface conditions. f there are any changes to the project characteristics or if different subsurface conditions are encountered during construction, HCEA should be consulted so that the recommendations of this report can be reviewed and revised, if necessary. 5.1 General Site Preparation All existing structures (including all above and below ground construction) within the areas to be developed should be removed prior to the initiation of new construction. We suggest that all available information regarding the existing utilities at the site be reviewed prior to construction. Removal should include all underground pipes, utilities, and underground structures that might interfere with the new construction. f abandoned underground utilities are to be removed prior to the initiation of construction, provisions should be made in the construction specifications and budget to restore the subgrade to stable condition. Restoration should include backfilling and compaction of the excavation areas. After the initial stripping process is completed, areas of the site to receive fill, or areas of the site at-grade where structures will be located, should be proofrolled. The proofrolling operations should be performed using a 20-ton, fully-loaded dump truck or another pneumatic-tire vehicle of similar size and HLLS-CARNES ENGNEERNG ASSOCATES, NC. 4

8 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study weight. The purpose of the proofrolling will be to locate any near-surface pockets of soft or loose soils requiring undercutting. A Geotechnical Engineer or experienced Soils nspector should witness the proofrolling operations and should determine which areas need further undercutting and/or stabilization. 5.2 Fill Selection, Placement and Compaction All material to be used as fill or backfill should be inspected, tested and approved by the Geotechnical Engineer. n general, the on-site soils which are free from organic and other deleterious components can be re-used as general site fill. Materials suitable for various construction purposes can be identified by an experienced Soils nspector during grading operations. Moisture conditioning (that is, wetting or drying) of the soils should be anticipated to achieve proper compaction. The moisture contents of the soils should be controlled properly to avoid extensive construction delays. f imported fill material is required, those materials should have Unified Soil Classifications of SM or better. All fill should be placed in relatively horizontal 8-inch (maximum) loose lifts and should be compacted to a minimum of 95 percent of the Standard Proctor (ASTM D-698) maximum dry density. Fill materials in landscape and other non-structural areas should be compacted to at least 90 percent of the Standard Proctor maximum dry density if significant subsidence of the fill under its own weight is to be avoided. Field moisture contents should be maintained within 2 percentage points of the optimum moisture content in order to provide adequate compaction. Structural fill should extend a minimum of ten feet beyond building lines where floor slabs are to be constructed on the fill. Fill slopes no steeper than 2(H):1(V), or flatter, should be used. A sufficient number of in-place density tests should be performed by an experienced Engineering Technician on a full-time basis to verify that the proper degree of compaction is being obtained. 5.3 Foundation Evaluations As stated previously, relatively soft and loose existing fill/possible fill materials were encountered to estimated depths of 17+ ft to ft below existing site grades at the site. As such, foundations for the proposed structure will require special consideration. Footings should not be placed on or over any existing fill materials. Footings should not be constructed on or over any existing fill materials. As such, it is recommended that the proposed structure be supported on a HLLS-CARNES ENGNEERNG ASSOCATES, NC. 5

9 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study deep foundation system consisting of either augered, cast-in-place concrete piles or drilled shafts. Alternatively, it may be possible to utilize alternative subgrade modification techniques (such as rammed-aggregate piers) in order to provide a shallow foundation alternative for the structure. t is recommended that the additional borings (that are to be drilled during the final study once the existing structure has been removed) be drilled to greater depths below existing site grades to be able to better evaluate the most economical foundation system for the structure. 5.4 Ground-Supported Slabs Floor slabs should be supported on approved, firm natural soils, or on new compacted fill. The slab subgrade should be prepared in accordance with the procedures outlined in Sections 5.1 and 5.2 of this report. n particular, the slab subgrade should be heavily proofrolled to delineate any soft or loose areas requiring undercutting and/or stabilization. Since relatively soft/loose fill materials were encountered in the borings drilled during this study, additional slab subgrade evaluation will be required during the final study. t should be anticipated that the modification of slab subgrade materials will be required at a minimum. Structurally supporting the slab may also need to be considered. t is recommended that the slab be directly supported on a minimum 4-inch layer of clean granular materials such as washed sand, clean sand and gravel, or screened, crushed stone. These materials will require acquisition from an off-site source. A suitable moisture/vapor barrier (that is, polyethylene sheeting) should also be provided. These procedures will provide a moisture break that will help to prevent capillary rise, dampness of the floor slabs and also help to cure the slab concrete. t is also recommend that construction joints on the slab surface and isolation joints between the slab and structural walls be provided (such that the slab would be groundsupported). On most projects, there is a significant time lag between initial grading and a point when the contractor is ready to pour the slabs-on-grade. Environmental conditions and construction traffic often disturb the subgrade soils. Provisions should be made in the construction specifications for the restoration of the subgrade soils to a stable condition prior to the placement of the concrete for the floor slabs. 5.5 Groundwater and Drainage Groundwater levels were monitored in the open boreholes. The shallowest groundwater encountered in the borings was located at a depth of ft below existing site grades in the caved borehole at the location of Boring B-5. Water that appeared to be perched within the existing fill materials HLLS-CARNES ENGNEERNG ASSOCATES, NC. 6

10 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study 6.0 REMARKS was encountered at a depth of 8.5+ ft in Boring B-4 and at a depth of 5.5+ ft in Boring B-5. t should be anticipated that additional water or perched water will be encountered at varying depths across the site. The magnitude of the impact of the water on construction will be dependent on the foundation and slab alternatives selected. Adequate drainage should be provided at the site to minimize any increases in the moisture contents of the foundation soils. All pavement or parking areas should be sloped away from the structure to prevent the ponding of water around the building. The site drainage should also be such that run-off onto adjacent properties is controlled properly. This report has been prepared to aid in the evaluation of the site for the proposed library construction. t is considered that adequate recommendations have been provided to serve as a basis for preliminary site evaluation. Additional recommendations can be provided as needed. These preliminary analyses and recommendations are, of necessity, based on the information made available to us at the time of the actual writing of the report and the on-site conditions, surface and subsurface, that existed at the time the exploratory borings were drilled. Further assumption has been made that the limited exploratory borings, in relation both to the areal extent of the site and to depth, are representative of conditions across the site. f subsurface conditions are encountered which differ from those reported herein, this Office should be notified immediately so that the analyses and recommendations can be reviewed and/or revised as necessary. t is also recommended that: 1. We be given the opportunity to review any plans and specifications in order to comment on the interaction of the soil conditions as described herein and the design requirements. 2. A Geotechnical Engineer or experienced Soils nspector be present at the site during the construction phase to verify installation according to the approved plans and specifications. This is particularly important during excavation, placement, and compaction of fill materials. Please note that successful completion of the project is dependent on your compliance with all of the recommendations provided in this report. While represented separately, the recommendations represent work that is intertwined. The successful completion of the project is specifically conditioned on your complying with all recommendations. HLLS-CARNES ENGNEERNG ASSOCATES, NC. 7

11 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study Our professional services have been performed, our findings obtained, and our recommendations prepared in accordance with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties either implied or expressed. Hillis-Carnes Engineering Associates, nc. assumes no responsibility for interpretations made by others based on work or recommendations made by HCEA. HLLS-CARNES ENGNEERNG ASSOCATES, NC. 8

12 DCPL CAPTOL VEW BRANCH LBRARY Preliminary Geotechnical Engineering Study APPENDX Figure 1: Project Location Map Figure 2: Boring Location Plan Subsurface Profile Particle Size Distribution Reports Records of Soil Exploration Field Classification Sheet HLLS-CARNES ENGNEERNG ASSOCATES, NC. 9

13 PROJECT LOCATON MAP HLLS-CARNES ENGNEERNG ASSOCATES, NC. Scale: Reduced Figure: 1

14 B-2 B-4 B-3 B-5 B-1 LEGEND: SOL BORNG LOCATON BORNG LOCATON PLAN DCPL - CAPTOL VEW BRANCH LBRARY Guilford Road, Suite A Annapolis Junction, Maryland (410) Fax: (410) CENTRAL AVE, SE WASHNGTON, DC 14465A 11/24/14 1" = 40' 1 WH AM MPJ

15 HLLS-CARNES ENGNEERNG ASSOCATES, NC. LOG OF BORNGS DCPL Capitol View Branch B B B B B Elevation in Feet Elevation in Feet Fill Description not given for: "FE" Low plasticity clay Description not given for: "O:" Description not given for: "OZ" Silty sand Description not given for: "0O" Low-high plasticity clays

16 Particle Size Distribution Report in. 3 in. 2 in. 1½ in. 1 in. ¾ in. ½ in. 3/8 in. #4 #10 #20 #30 #40 #60 #100 #140 # PERCENT FNER GRAN SZE - mm. % +3" % Gravel % Sand % Silt % Clay SEVE PERCENT SPEC.* PASS? SZE FNER PERCENT (X=NO) 3" 2" 1 1/2" 1" 3/4" 3/8" #4 #10 #40 #100 # Material Description Orange brown silty sand Atterberg Limits PL= NP LL= NP P= NP Coefficients D 90 = D 85 = D 60 = D 50 = D 30 = D 15 = D 10 = C u = C c = Classification USCS= SM AASHTO= A-2-4(0) Remarks Moisture Content: 6.9% * (no specification provided) Location: B-1, S-9 Sample Number: 1 Depth: 33.5'-35.0' Date: HLLS-CARNES ENGNEERNG ASSOCATES, NC. Annapolis Junction, MD Client: Project: Project No: DCPL - Capitol View Branch Library 14465A Figure 01/23/15

17 Particle Size Distribution Report in. 3 in. 2 in. 1½ in. 1 in. ¾ in. ½ in. 3/8 in. #4 #10 #20 #30 #40 #60 #100 #140 # PERCENT FNER GRAN SZE - mm. % +3" % Gravel % Sand % Silt % Clay SEVE PERCENT SPEC.* PASS? SZE FNER PERCENT (X=NO) 3" 2" 1 1/2" 1" 3/4" 3/8" #4 #10 #40 #100 # Material Description Red with brown fat clay Atterberg Limits PL= 26 LL= 64 P= 38 Coefficients D 90 = D 85 = D 60 = D 50 = D 30 = D 15 = D 10 = C u = C c = USCS= CH Classification AASHTO= Remarks Moisture content: 18.4% A-7-6(45) * (no specification provided) Location: B-3, S-6 Sample Number: 2 Depth: 18.5'-20.0' Date: HLLS-CARNES ENGNEERNG ASSOCATES, NC. Annapolis Junction, MD Client: Project: Project No: DCPL - Capitol View Branch Library 14465A Figure 01/23/15

18 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-1 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 12/3/14 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/2/15 Elevation/ Depth SOL SYMBOLS/ SAMPLE CONDTONS Description Orange-Brown, moist, loose clayey SAND with gravel. (SC) Possible Fill Gray/Orange-Brown, moist, soft CLAY with sand and organics (CL) Possible Fill Light Brown, moist, soft CLAY with silt and trace sand (CL) Possible Fill Boring and Sampling Notes 3" of Asphalt 2" of Stone Rec. NM% SPT Blows 16" 15" N SPT Blows/Foot C u r v e Mottled Light Gray/Dark Red- Brown/Orange-Brown, moist, very stiff CLAY with fine sand (CL) Possible Fill Mottled Brown/Orange-Brown/Dark Gray, moist, very stiff SLT with clay and sand (ML) Possible Fill 7" Light Brown, moist, very stiff CLAY with silt, trace sand (CL) Gray with Yellow-Brown, moist, very stiff sandy CLAY (CL) Brown/Gray, moist, very stiff silty CLAY with sand (CL) Light Red-Brown to Gray, moist, GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

19 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-1 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 12/3/14 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/2/15 Elevation/ Depth 35 SOL SYMBOLS/ SAMPLE CONDTONS Description very dense silty SAND (SM) Boring and Sampling Notes Rec. NM% SPT Blows N SPT Blows/Foot C u r v e Groundwater encountered at 38.5 while drilling 17" /5" Bottom of boring at 45 ft Boring backfilled with grout and patched at completion GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

20 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-2 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 1/6/15 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/6/15 Elevation/ Depth SOL SYMBOLS/ SAMPLE CONDTONS Description Orange-Brown/Dark Brown/Gray, moist, loose clayey SAND with gravel and organics (SC) Possible Fill Mottled Light Gray/Red-Orange- Brown/Dark Brown/Yellow-Brown, moist, medium stiff sandy CLAY (CL) Possible Fill Dark Brown/Brown, moist, stiff, sandy SLT with clay (ML) Possible Fill Mottled Brown/Orange-Brown, moist, very loose to medium dense silty fine SAND with clay (SM) Possible Fill Boring and Sampling Notes 1" of Topsoil Rec. NM% SPT Blows 14" 13" 15" 17" N SPT Blows/Foot C u r v e " Red-Brown with Light Gray, moist, very stiff sandy CLAY (CL) Light Red-Brown, moist, dense silty SAND (SM) Light Red-Brown, moist, dense to Groundwater GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

21 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-2 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 1/6/15 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/6/15 Elevation/ Depth 35 SOL SYMBOLS/ SAMPLE CONDTONS Description very dense silty SAND with Light Red-Brown clay seams (SM) Boring and Sampling Notes encountered at 35 ft while drilling Rec. NM% SPT Blows N SPT Blows/Foot C u r v e Light Red-Brown to Gray, moist, very dense silty SAND (SM) Bottom of boring at 45 ft Boring backfilled with grout and patched at completion GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

22 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-3 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 1/5/15 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/5/15 Elevation/ Depth SOL SYMBOLS/ SAMPLE CONDTONS Description Orange-Brown, moist, very loose clayey SAND with gravel (SC) Possible Fill Orange-Brown to Orange-Brown/ Yellow-Brown /Light Gray, moist, soft sandy CLAY (CL) Possible Fill Boring and Sampling Notes 4" of Asphalt 2" of Stone Rec. NM% SPT Blows 10" 8" 10" N SPT Blows/Foot C u r v e Orange-Brown, moist, very loose clayey SAND (SC) Possible Fill Groundwater encountered at 13.5 ft while drilling 13" Brown/Orange-Brown, very moist, very loose clayey GRAVEL and SAND (GC-SC) Possible Fill 3" Red-Brown/Brown, moist, very stiff CLAY with silt and trace to some sand (CL-CH) 17" Light Red-Brown to Gray, moist, dense to very dense silty SAND (SM) GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

23 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-3 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 1/5/15 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/5/15 Elevation/ Depth 35 SOL SYMBOLS/ SAMPLE CONDTONS Description Boring and Sampling Notes Rec. NM% SPT Blows N SPT Blows/Foot C u r v e Bottom of boring at 45 ft Boring backfilled with grout and patched at completion GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

24 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-4 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 1/5/15 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/5/15 Elevation/ Depth SOL SYMBOLS/ SAMPLE CONDTONS Description Orange-Brown/Red-Brown/Gray, moist, stiff sandy CLAY with gravel (CL) Possible Fill Gray with Yellow-Brown, moist, medium stiff CLAY (CL) Possible Fill Red-Brown with Gray to Gray, moist to wet, very loose silty SAND (SM) Possilbe Fill Boring and Sampling Notes 4" of Asphalt No Stone Encountered Groundwater encountered at 8.5 ft while drilling Rec. NM% SPT Blows 16" 17" 17" WOH/12"-1 N SPT Blows/Foot C u r v e Gray/Yellow-Brown, moist, medium stiff CLAY with sand (CL) Possible Fill 15" Red-Brown/Light Gray to Red Brown, moist, very stiff to hard sandy CLAY (CL) GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

25 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-4 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 1/5/15 Pipe Size 2.0 in. Boring Method HSA Date Completed 1/5/15 Elevation/ Depth 35 SOL SYMBOLS/ SAMPLE CONDTONS Description Boring and Sampling Notes Rec. NM% SPT Blows N SPT Blows/Foot C u r v e Light Red-Brown/Gray to Gray, moist, dense to very dense silty SAND (SM) 17" /5" Bottom of boring at 45 ft Boring backfilled with grout and patched at completion GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON Dry ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

26 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-5 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 12/31/14 Pipe Size 2.0 in. Boring Method HSA Date Completed 12/31/14 Elevation/ Depth 110 SOL SYMBOLS/ SAMPLE CONDTONS Description Mottled Dark Brown/Red-Brown Dark Gray, moist, very loose silty SAND with no to trace clay(sm) Possible Fill Boring and Sampling Notes 3" of Asphalt 2" of Stone Rec. NM% SPT Blows 14" " N 5 3 SPT Blows/Foot C u r v e Dark Brown/Red-Brown/Dark Gray, moist, soft to very soft CLAY with sand (CL) Possible Fill Groundwater encountered at 5.5 ft 16" 1/12" " Red-Brown/Brown, very moist, very dense silty SAND with gravel (SM) Possible Fill Light Brown/Orange-Brown to Mottled Light Gray/Dark Red- Brown/Orange-Brown, moist, very stiff to hard CLAY with silt and trace sand (CL) 14" Light Red-Brown to Gray, moist, GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON 25.2 ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

27 STANDARD PENETRATON TEST-DRVNG 2" O.D. SAMPLER 1' WTH 140# HAMMER FALLNG 30": COUNT MADE AT 6" NTERVALS. HLLS - CARNES ENGNEERNG ASSOCATES, NC. RECORD OF SOL EXPLORATON Project Name DCPL Capitol View Branch Boring No. B-5 Location Washington DC, SE Job # 14465A SAMPLER Datum MSL Hammer Wt. 140 lbs. Hole Diameter 6" Foreman M. Stawas Surf. Elev ft Hammer Drop 30 in. Rock Core Diameter N/A nspector W. Harris Date Started 12/31/14 Pipe Size 2.0 in. Boring Method HSA Date Completed 12/31/14 Elevation/ Depth SOL SYMBOLS/ SAMPLE CONDTONS Description dense to very dense silty SAND (SM) Boring and Sampling Notes Rec. NM% SPT Blows N SPT Blows/Foot C u r v e " 27-50/5" Bottom of Boring at 45 ft Boring backfilled with grout and patched at completion GROUND WATER SAMPLER TYPE SAMPLE CONDTONS BORNG METHOD DRVEN SPLT SPOON UNLESS OTHERWSE D - DSNTEGRATED AT COMPLETON 25.2 ft ft. HSA - HOLLOW STEM AUGERS PT - PRESSED SHELBY TUBE - NTACT AFTER 24 HRS. ft. ft. CFA - CONTNUOUS FLGHT AUGERS CAVE N DEPTH CA - CONTNUOUS FLGHT AUGER U - UNDSTURBED AFTER HRS. ft. ft. DC - DRVNG CASNG RC - ROCK CORE L - LOST MD - MUD DRLLNG

28 HLLS-CARNES ENGNEERNG ASSOCATES, nc Guilford Road, Suite A Annapolis Junction, Maryland Phone: (410) Fax: (410) Description of Soils per ASTM D2487 Major Component Component Type Component Description Symbol Group Name Coarse-Grained Soils, Gravels More than 50% of the coarse Clean Gravels <5% GW Well Graded Gravel More than 50% is fraction is retained on the No. 4 sieve. Passing No. 200 sieve GP Poorly Graded Gravel retained on the No. 200 Coarse = 1 to 3 Gravels with fines, >12% GM Silty Gravel sieve Medium = ½ to 1 Passing the No. 200 sieve GC Clayey Gravel Fine = ¼ to ½ Sands More than 50% of the coarse Clean Sands <5% Passing SW Well Graded Sand fraction passes the No. 4 sieve. No. 200 sieve SP Poorly Graded Sand Coarse = No.10 to No.4 Sands with fines, >12% SM Silty Sand Medium = No. 10 to No. 40 Passing the No. 200 sieve SC Clayey Sand Fine = No. 40 to No. 200 Fine Grained Soils, Silts and Clays norganic ML Silt More than 50% passes Liquid Limit is less than 50 CL Lean Clay the No. 200 sieve Low to medium plasticity Organic OL Organic silt Organic Clay Silts and Clays norganic MH Elastic Silt Liquid Limit of 50 or greater CH Fat Clay Medium to high plasticity Organic OH Organic Silt Organic Clay Highly Organic Soils Primarily Organic matter, dark color, organic odor PT Peat Proportions of Soil Components Particle Size dentification Component Description Approximate percent Particle Size Particle dimension Form by weight Noun Sand, Gravel, Silt, Clay, etc. 50% or more Boulder 12 diameter or more Adjective Sandy, silty, clayey, etc. 35% to 49% Cobble 3 to 12 diameter Some Some sand, some silt, etc. 12% to 34% Gravel ¼ to 3 diameter Trace Trace sand, trace mica, etc. 1% to 11% Sand to ¼ diameter With With sand, with mica, etc. Presence only Silt/Clay (fines) Cannot see particle Cohesive Soils Granular Soils Field Description No. of SPT Consistency No. of SPT Blows/ft Relative Density Blows/ft Easily Molded in Hands 0 3 Very Soft 0 4 Very Loose Easily penetrated several inches by thumb 4 5 Soft 5 10 Loose Penetrated by thumb with moderate effort 6 10 Medium Medium Dense Penetrated by thumb with great effort Stiff Dense ndented by thumb only with great effort Greater than 30 Hard Greater than 50 Very Dense Other Definitions: Fill: Encountered soils that were placed by man. Fill soils may be controlled (engineered structural fill) or uncontrolled fills that may contain rubble and/or debris. Saprolite: Soil material derived from the in-place chemical and physical weathering of the parent rock material. May contain relic structure. Also called residual soils. Occurs in Piedmont soils, found west of the fall line. Disintegrated Rock: Residual soil material with rock-like properties, very dense, N = 60 to 51/0. Karst: Descriptive term which denotes the potential for solutioning of the limestone rock and the development of sinkholes. Alluvium: Recently deposited soils placed by water action, typically stream or river floodplain soils. Groundwater Level: Depth within borehole where water is encountered either during drilling, or after a set period of time to allow groundwater conditions to reach equilibrium. Caved Depth: Depth at which borehole collapsed after removal of augers/casing. ndicative of loose soils and/or groundwater conditions.