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HomeMy WebLinkAboutSubsurface Exploration StudyEngineering & Environmental Consultants, Inc. September 26, 2008 Mr. Wallace Phillips Greens Prairie Investors, Ltd. 4490 Castlegate Drive College Station, TX 77845 Re: Report of Subsurface Exploration and Geotechnical Study Performed for the Proposed Barracks Subdivision (Phases I and 2) Rock Prairie Road West College Station (Brazos County), Texas Dear Mr. Phillips: Enclosed please find three (3) copies (two bound and one unbound) of CSC Engineering & Environmental Consultants, Inc. 's (CSC ) report entitled "Report of Subsurface Exploration and Geotechnical Study for The Barracks Subdivision; College Station (Brazos County), Texas." The report documents the results of the surface exploration and geotechnical study for the proposed Barracks Subdivision that will be located in the southwestern portion of College Station, Texas. The subsurface information and general foundation design values presented in this report are offered to guide the foundation design of proposed residential structures, and selection/construction of various pavement options for the proposed subdivision. The analysis, conclusions, and design values presented in this report are based upon the subsurface exploration program that consisted of thirty-one (31) borings. The borings were located across the approximately 13 .5-acre area of the proposed residential subdivision development. The field operations in which borings were drilled were conducted on September 9 and 10, 2008. Geotechnical laboratory testing for the project was completed on September 19, 2008. We understand that conventional sla6-on-grade foundation systems are the preferred method of foundation support for the residential structures planned within the subdivision. Therefore, the recommendations and general foundation values presented in the accompanying report are presented only for the preferred type of foundation system. We anticipate that the slab-on-grade foundation systems will be adequately stiffened and reinforced to accommodate the magnitudes of shrink-swell movement and anticipated magnitude of settlement presented in the report. The developer and designer should be aware that there is always a risk of foundation movement and possible foundation or structure distress when a shallow slab-on-grade foundation system is employed in an area where soils with potential significant shrink-swell movements comprise the subsurface stratigraphy, or in fill areas that may experience noticeable magnitudes of settlement, such as at the referenced subdivision site. Recommendations regarding measures that may be employed to minimize the magnitude of these vertical movements are discussed in detail in the accompanying reports. If the designer of the foundation systems desires to have foundation recommendations for individual structures on individual lots, then specific geotechnical studies should be conducted for each lot location to develop specific infonnation for final engineering design of individual foundation systems. 3407 Tabor Road Bryan, Texas n808 Phone (979) n8-2810 Fax (979) n8-0820 - Transmittal of Report of Geotechnical Study Proposed Barracks Development -Phase I and 2 College Station, (Brazos County), Texas Page 2 The report also presents recommendations for pavement design for the residential roadways that wi ll be constructed as part of the planned development. The recommendations are offered both for rigid pavement sections composed of reinforced Portland cement concrete and for flexible pavement systems that have a hot-mix asphalt concrete surface course and a crushed rock base course. The report also offers guidance concerning chemical stabilization of the subgrade soils for both types of pavement systems. An important aspect to the successful performance of the foundation and pavement systems that will be constructed as part of the planned development is support capacity of the backfill soils in the areas of former pond locations within the boundaries of the proposed subdivision. Specifically, information developed during the geotechnical study indicates that the pond depths at the site were generally on the order of 3 to 3.5 feet, as measured from the ground surface existing at the time of the field study. It is our understanding that construction quality assurance (CQA) testing was not conducted during the initial backfilling of the referenced ponds. The absence of such documentation will necessitate CQA verification testing prior to further site development to ensure compliance with City specifications and to minimize consolidation of backfill soils beneath the roadways under anticipated traffic loading. In addition, site preparation beneath the townhomes wi ll also have to be addressed as part of future construction activities. Each of these issues is addressed in the attached report. Please contact us at (979) 778-281 0 if you have any questions or need additional information concerning this matter. We appreciate the opportunity to have worked with you on this project. Respectfully, W.R. Cullen, P.E. Senior Engineer WRC:mf Enclosure Via Hand Delivery CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. W.R. Cullen, P.E. Senior Engineer REPORT OF SUBSURFACE EXPLORATION AND GEOTECHNICAL STUDY FOR THE BARRACKS SUBDIVISION COLLEGE STATION (BRAZOS COUNTY), TEXAS Prepared for Greens Prairie Investors, Ltd. 4490 Castlegate Drive College Station, Texas 77845 Prepared by CSC Engineering & Environmental Consultants, Inc. 3407 Tabor Road Bryan, Texas 77808 CSC Project Number: 27109 September 26, 2008 111~Shno~CorJl,~. M. Frederick Conlin, Jr., P.E. ~ Senior QA Reviewer - Report of Geotechnical Study The Barracks Subdivision; College Station, TX TABLE OF CONTENTS Page 1.0 INTRODUCTION .......................................................................................................................... l 1.1 PROJECT DESCRIPTION ................................................................................................... l 1.1. l Scope of Planned Development.. ............................................................................. l 1.1.2 Anticipated Types of Structures and Preferred Foundation Systems ...................... 2 1.1.3 Proposed Subdivision Roadways ............................................................................. 2 1.1.4 Site Grading ............................................................................................................. 4 1.1.5 Roadways and Utilities ............................................................................................ 4 1.2 OBJECTIVES AND SCOPE OF THE EXPLORATION AND STUDY ............................ 4 1.3 LIMIT A TIO NS OF SCOPE OF STUDY ............................................................................. 5 1.4 REPORT FORMAT ............................................................................................................. 5 2.0 FIELD EXPLORATION PROGRAM ........................................................................................... 7 2.1 OUTLINE OF SUB SURF ACE EXPLORATION PROGRAM ........................................... 7 2.2 DRILLING AND SAMPLING ............................................................................................. 7 2.3 GROUNDWATER OBSERVATION .................................................................................. 8 2.4 BORING LOGS .................................................................................................................... 8 2.5 SAMPLE CUSTODY ........................................................................................................... 9 3.0 LABORATORY TESTING PROGRAM ....................................................................................... 10 3.1 CLASSIFICATION AND MOISTURE CONTENT TESTS ............................................... 10 3.2 STRENGTH TESTS AND UNIT DRY WEIGHT DETERMINATIONS .......................... 10 4.0 SITE CONDITIONS ...................................................................................................................... 12 4.1 GENERAL SURFACE CONDITIONS ................................................................................ 12 4.2 GENERAL SUBSURFACE STRATIGRAPHY .................................................................. 12 4.2. l Classification System Used in Subsurface Descriptions ......................................... 12 4.2.2 General Description of Subsurface Stratigraphy ..................................................... 13 4.3 SUBSURFACE WATER CONDITIONS ............................................................................ 15 5.0 ANALYSIS AND RECOMMENDATIONS ................................................................................. 17 5.1 GENERAL FOUNDATION ANALYSIS ............................................................................ 17 5.2 GENERAL CONSIDERATIONS -POTENTIAL VOLUMETRICALLY ACTIVE FOUNDATION SOILS AND ALTERNATE TYPES OF FOUNDATION SYSTEMS ............................................................................................................................ 17 5.3 MAGNITUDES OF POTENTIAL SHRINK-SWELL MOVEMENTS .............................. 18 5.3 .l Calculation of Magnitudes of Potential Total Shrink-Swell Movements for Existing Soils Stratigraphy ...................................................................................... 18 5.3.2 Potential Differential Shrink-S well Movements ..................................................... 19 5.4 TYPES OF FOUNDATION SYSTEMS CONSIDERED AND SUPERSTRUCTURE DETAILING ......................................................................................................................... 19 5.4. l Use of Shallow Foundation System and Risk of Distress Associated with Potential Shrink-Swell Movements of Foundation Soils ......................................... 19 5 .4.2 Inherent Risks of Distress Involved with Shallow Foundation Systems ................. 20 5.4.3 Measures to Reduce Risks of Distress Involved with Shallow Foundation Systems .................................................................................................................... 21 6.0 SPECIFIC FOUNDATION RECOMMENDATIONS FOR SHALLOW FOUNDATION SYSTEMS -CONVENTIONAL WAFFLE SLAB (B.R.A.B. TYPE III SLAB) ......................... 22 6.1 GENERAL ............................................................................................................................ 22 II - Report of Geotechnical Study The Barracks Subdivision; College Station, TX 6.2 MINIMUM FOOTING FOUNDING DEPTHS AND FOUNDING FORMATIONS ......... 22 6.3 MINIMUM FOOTING WIDTHS AND MAXIMUM ALLOW ABLE BEARING VALUES ............................................................................................................................... 23 6.4 POTENTIAL FOOTING MOVEMENTS ............................................................................ 23 6.5 OTHER B.R.A.B. DESIGN VALUES ................................................................................. 24 .0 ;..;..=~M:..;.:-ENT RECOMMENDATIONS ......................................................................................... 26 G RAL DESIGN CRITERIA USED FOR PAVEMENT ANALYSES ........................ 26 7.1.1 General Considerations of Subgrade Support for Pavement Systems ..................... 26 7.2 PR JECTED TRAFFIC VOLUMES AND CHARACTERISTICS .................................... 28 7.3 VEMENT THICKNESS REQUIREMENTS .................................................................. 28 PAVEMENT SYSTEM MAINTENANCE .......................................................................... 32 7 .4.1 Pavement Drainage .................................................................................................. 32 7.4.2 Pavement Maintenance ............................................................................................ 32 CON CTION CONSIDERATIONS ...................................................................................... 33 8.1 SITE PARATION -CLEARING AND SUBGRADE PREPARATION ..................... 33 8.2 SITE P PARA TION -DRAINAGE AND MOISTURE CONTROL .............................. 36 8.3 BUILD G AREA ("SELECT") FILL AND GENERAL PAVEMENT AREA FILL MAT L SELECTION AND PLACEMENT PROCEDURES ...................................... 3 7 S LOW CONTINUOUS FOOTING EXCAVATIONS ................................................ 38 OUNDATION CONCRETE .............................................................................................. 38 PAVEMENT SUBGRADE SOILS STABILIZATION REQUIREMENTS ........................ 39 PAVEMENT MATERIAL REQUIREMENTS ................................................................... 40 8. 7 .1 HMAC Surface Course (Flexible Pavement Section) ............................................. 40 8. 7.2 Base Course (Flexible Pavement Section) ............................................................... 40 8.7.3 PCC Surface Course ................................................................................................ 41 9.0 BASIS OF RECOMMENDATIONS ............................................................................................. 42 LIST OF TABLES Table 1. Recommended Unit Net Allowable Bearing Pressures for Shallow Continuous Footings (Grade Beams) ....................................................................................................... 24 Tub le 2. :vement Thickness Schedule for Rigid Pavement System Composed of PCC for Res· dential and Minor Collector Streets Planned for the Proposed Subdivision ................. 29 Table 3. Pav ment Thickness Schedule for Flexible (HMAC) Pavement Section with Crushed Ro Base Course for Residential and Minor Collector Streets Planned for the oposed Subdivision ........................................................................................................... 30 Alternate Pavement Thickness Schedule for Flexible (HMAC) Pavement Section with Full Depth HMAC for Residential and Minor Collector Streets Planned for the Proposed Subdivision ........................................................................................................... 30 LIST OF APPENDICES Appendix A -Report Figures, Boring Logs, and Key to Symbols and Soil Classification Used on the Boring Logs Appendix B -Summary of Laboratory Test Results 111 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 1.0 INTRODUCTION This report documents the results of the subsurface exploration and geotechnical study performed by CSC Engineering & Environmental Consultants, Inc. (CSC) to determine general geologic conditions at the site of the proposed Barracks Development. The proposed development will be located on Rock Prairie Road West approximately 1,000 feet northwest of the Rock Prairie Road West intersection with Wellborn Road in College Station, Texas, as illustrated on Figure 1 -Project Vicinity Map in Appendix A of this report. This study was performed in accordance with a scope of work discussed with Greens Prairie Investors, Ltd. on September 5, 2008. The written scope of services for the study was outlined in our proposal to Greens Prairie Investors, Ltd. dated September 12, 2008. Written authorization for the study was given by Mr. Wallace Phillips on September 14, 2008. Field activities for this project were initiated on September 9, 2008, and completed on September 10, 2008. The laboratory testing program was completed on September 19, 2008. A summary of the field and laboratory phases of the project and a discussion of foundation and pavement system design values are presented for review and consideration. 1.1 PROJECT DESCRIPTION Information concerning the project was provided during conversations with Greens Prairie Investors, Ltd. and in the form of preliminary site development plans prepared by Civil Design Limited. 1.1.1 Scope of Planned Development We understand that Greens Prairie Investors, Ltd. plans to develop approximately 13.5 acres of real property located approximately 1,000 feet northwest of the Rock Prairie Road West intersection with Wellborn Road in College Station, Texas. The proposed project site was formerly used as a commercial aqua culture facility and supported numerous shallow (3-3.5 feet deep) ponds that were constructed throughout the site. At the time of this report, the utilities infrastructure installation was initiated for the development. It is anticipated that these installation activities will be pursued and monitored in accordance with Bryan/College Station Unified Design Guidelines for Domestic Water, Sanitary Sewer, and Streets and Alleys (2008). As a result, design recommendations for these infrastructure items were not developed as part of this study. - Report of Geoteclmjcal Study The Barracks Subdivision; College Station, TX The proposed subdivision will be a "phased" development as illustrated on Figure 2 -Site Plan and Plan of Borings in Appendix A. Phase 1 of the proposed Barracks Subdivision will consist of 54 individual lots that will support townhouses that will be constructed as single-story structures with individual footprint dimensions of approximately 55 ft x 27 ft and "footprint" areas of approximately 1,485 sq ft. Phase 2 will consist of an additional 50 residential lots that will be developed similar to Phase 1. 1.1.2 Anticipated Types of Structures and Preferred Foundation Systems No specific details are currently avai lable concerning the planned residential structures. However, we anticipate that the proposed townhomes that will be located on the lots of the referenced subdivision will be single story in height and will be roughly rectangular in shape. The townhomes will be constructed in groups of six (six-plexes), each of which will be supported by a common, continuous foundation system. No specific details are currently available concerning the type of structural framing systems planned for the proposed townhomes, but we anticipate that the townhomes will have superstructure systems consisting of conventional wood-stud bearing wall/frame construction. We also anticipate that maximum bearing wall loads will be in the range of 1,200 to 1,500 pounds per linear foot of wall (pit) and that sustained or continuous loads will be in the order of 600 to 800 plf. We believe that the exterior face or "sbn" of the buildings will consist of a combination of masonry walls, such as brick or stone, and wood siding or Hardi-planks. Preferred Foundation Systems CSC understands that the preferred method of foundation support for each of the proposed townhomes is by a shallow foundation system composed of a conventional slab-on-grade that will be adequately stiffened and reinforced to acconm1odate predicted foundation movements. We further understand that other types of foundation systems that address potential shrink-swell movements of the foundation soils in a more affirmative manner, including deeper foundation systems that incorporate drilled piers and structural floor systems, are not being considered by the owner for economic reasons and will therefore not be directly addressed in this report. 1.1.3 Proposed Subdivision Roadways We believe that all of the proposed roadways within the subdivision, with the exception of General Parkway, will be classified as residential streets that will be constructed within a right-of-way (ROW) that will have a width in the order of 50 feet. General Parkway will be constructed as a minor 2 I. Report of Geotechnical Study The Barracks Subdivision; College Station, TX collector of the subdivision in a 60 ft ROW. We believe that the proposed residential streets will have a typical urban roadway cross-section with a back-of-curb pavement section width that is approximately 27 feet and the minor collector will have a back of curb pavement section of 38 ft. We also anticipate that the constructed pavement sections will consist either of rigid pavement sections composed of a PCC surface course, or of flexible pavement sections with a hot-mix asphalt concrete (HMAC) surface course and a crushed rock base course or full depth HMAC section. We believe that both types of pavement sections will be installed over a chemically stabilized and compacted subgrade soil layer. Traffic Characterization The character and volume of the traffic utilizing the proposed residential streets have not been specifically defined, but we believe that the residential streets will have the traffic volumes and character that are consistent with such a classification. Residential streets are typically defined as streets that primarily serve vehicular traffic to abutting residential properties and may also provide limited access to commercial properties. We believe that typical average daily traffic (ADTs) counts for residential streets are in the range of 500 to 1,000 vehicles per day. Therefore, an average ADT of 1,000 VPD was used for pavement design of the subject residential streets. The traffic volume is believed to be representative for the average daily traffic over a 20-year design period. Therefore, the stated ADT is assumed to have already incorporated growth factors over the indicated 20-year design period. Similarly, General Parkway will have ADTs consistent with those of a minor collector and in the range of 1,000 to 5,000 VPD. A minor collector primarily serves vehicular traffic from residential streets to collectors or arterials. By definition, the ADT represents two-way traffic per day. An average traffic directional split of 50 percent was assumed for the project. Therefore, the design traffic volume for each of the drive lanes of the proposed residential streets was assumed to be one-half of the referenced ADT, or approximately 500 VPD. The ADT for the minor collector was assumed to be in the range of 500 to 2,500 VPD. Considering the basic residential character of the proposed development, the lack of arterial streets within the proposed subdivision, and the residential character of many of the properties adjacent to the proposed subdivision, we believe that most of the vehicles using the proposed subdivision will consist of light passenger vehicles with some occasional use by light weight trucks. The passenger vehicles are expected to have two axles and gross vehicle weights in the range of 3,000 to 4,000 pounds. The light weight trucks are expected to have two axles and gross vehicle weights in the range of 7 ,000 to 12,000 pounds. The percentage of truck traffic and in particular heavy truck traffic that will be part of the daily vehicle count for the proposed subdivision will be relatively low and probably in the order of l percent or less. 3 Repo11 of Geotechnical Study The Barracks Subdivision; College Station, TX 1.1.4 Site Grading Grading plans for the proposed development are not known at the present time. Based upon the existing grades at the site and the relative elevations of the surrounding roadways, we do not anticipate that extensive volumes of "new" fill soils will be required to achieve final site grade. However, the exact height or thickness of fill soils required to be added to the site is not known at the present time. Nonetheless, it should be noted that an important aspect to this project is the evaluation of the condition of the previously backfilled ponds beneath planned roadway ROWs and townhome structures. In addition, we understand no basements, swimming pools, or other subsurface structures that require structural excavations will be associated with any of the townhomes planned for the proposed development. 1.1.5 Roadways and Utilities We anticipate that all of the roadways and utilities planned at the site will be constructed in accordance to the Bryan/College Station Unified Design Guidelines for Streets and Alleys (2008) and that specific recommendations concerning subgrade soil preparation and pavement layer thickness requirements, as well as utility bedding and backfill requirements, need not be addressed in this report. However, we have presented some general roadway design section recommendations that include evaluation of existing subgrade fill soils in the former pond areas for general considered by the designers of the subdivision. 1.2 OBJECTIVES AND SCOPE OF THE EXPLORATION AND STUDY The specific objectives of the exploration and study were to: • • Secure subsurface geologic information regarding the conditions across the site by drilling thirty-one (31) borings throughout the area of the planned subdivision development and by testing selected recovered samples in the laboratory. Evaluate the subsurface information developed from the field exploration and laboratory testing programs. • Develop general recommendations based upon an engineering analysis of the subsurface information at the thirty-one (31) boring locations across the site to guide the design of foundation and pavement plans for proposed subdivision. If the designer of the foundation systems desires to have foundation recommendations for individual structures on individual lots, then specific geotechnical studies should be conducted for each lot location to develop specific information for final engineering design of individual residential foundation systems. 4 ... Report of Geo technical Study The Barracks Subdivision; College Station, TX 1.3 LIMITATIONS OF SCOPE OF STUDY It should be recognized that the exclusive purpose of this study was to develop general recommendations for the conceptual design of the planned residential structures in the indicated areas of the subdivision. This study did not directly assess, or even attempt to address, specific environmental conditions encountered at the site (e.g., the presence of waste products or fuels or pollutants in the soil, rock, or groundwater), historical uses of the site, threatened or endangered species, or the presence of jurisdictional wetlands or "waters of the United States" on the site. Such environmental issues are typically addressed as part of a separate study known as an environmental site assessment (ESA) or ecological assessment (EA). 1.4 REPORT FORMAT The following sections of this report initially present descriptions of work and test procedures employed to collect the subsurface information for the project. The later sections of the report present analysis of the information developed from the field and laboratory studies and offer recommendations for foundation support of the proposed proj ect elements. First, descriptions of the field exploration program are presented in Section 2. The descriptions include the drilling and sampling techniques employed as part of the field exploration. Appendix A contains the site vicinity map and the site plan of borings that illustrates the relative location of the exploratory borings. The boring logs, which indicate the types of soils encountered at each of the boring locations and present the results of some field test procedures and observations, are also presented in Appendix A. Section 3 of the report presents a discussion of the laboratory tests performed for the project that included references to the American Society of Testing and Materials (ASTM) standard laboratory test procedures employed. The summary results of the laboratory testing program are presented in tabular form in Appendix B. Some laboratory test results are also presented numerically and symbolically on the boring logs in Appendix A. Section 4 of the report offers a description of our observations of surface conditions at the site at the time of the field study. A general discussion and interpretation of subsurface conditions based upon the borings performed as part of the field exploration and based upon limited laboratory test results of some of the soils recovered as part of that field exploration are also presented in Section 4. Section 5 presents a general di scussion of foundation conditions that should be considered in the selection of the foundation systems for the proposed residential structures and in the formulation of 5 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX general conceptual designs of the foundation systems for the proposed townhomes within the subdivision. Section 6 of this report presents CSC's recommendations for the design and construction of the proposed conventionally reinforced shallow slab-on-grade foundation systems that are planned for the proposed townhomes within the subdivision. Section 7 presents CSC's evaluation of existing and proposed subgrade soils in the areas proposed for paving and offers recommendations for the design and construction of either rigid or flexible pavement systems for the planned residential roadways within the subdivision. The pavement recommendations also include a discussion of subgrade soil preparation. Section 8 offers a discussion of individual site development and construction considerations and presents specific guidance with respect to subsurface conditions that may impact site development and construction activities. Recommendations concerning preparation of building pads and development of the lots to control drainage are also included in Section 8. Finally, Section 9 outlines the basis for the recommendations given in the report and the general limitations for the presented information. 6 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 2.0 FIELD EXPLORATION PROGRAM 2.1 OUTLINE OF SUBSURFACE EXPLORATION PROGRAM Subsurface conditions across the site of the proposed subdivision development were explored by drilling a total of thirty-one (31) sample borings (B 1 through B3 l) at the approximate locations indicated on the previously referenced Figure 2. Two types of borings were advanced as part of the field study: ( 1) foundation borings, and (2) roadway or pavement borings. The foundation borings, designated as B 1 through B 10, and B25 through B3 l were situated beneath planned townhomes and were advanced to depths of 15 feet below existing grade. Similarly, the pavement borings designated as B 11 through B24, were situated within the ROWs of the residential streets that will be constructed as part of the development and were advanced to depths of 6 feet. In general, the boring locations were situated in a manner that would allow the collection of general subsurface geologic infomrntion throughout the area of interest. However, emphasis was given to placement of the majority of the borings within former pond areas that were previously backfilled in an attempt to characterize the type and nature of the fill soils used during backfilling operations. The boring locations were selected by CSC and located in the field by Texcon General Contractors, Inc. (Texcon). Topographic eleva tions at each of the boring locations were also obtained by Texcon and reflect the surface elevation that existed at the time of th e field study. It should be noted that subsequent discussions and recommendations presented in this report are referenced to the surface grade existing at the time of the field study. If changes to the present surface elevations are made as part of site grading operations prior to construction of the foundation systems, some adjustment in the subsequent discussions and recommendations with respect to foundation depths may be necessary. 2.2 DRILLING AND SAMPLING The borings were drilled with a truck-mounted, rotary drill rig utilizing dry augering drilling techniques. Representative soil samples were obtained continuously to a maximum depth of 10 ft, and thereafter samples were obtained at 5-ft intervals to the depth of termination. Cohesive soil samples were obtained by mechanically pushing a 3-inch-diameter, thin-wall sampler in general accordance with the procedures outlined in ASTM D 1587. Samples of cohesive-granular or granular soils or cohesive soils that are too hard to be sampled with a tube are typically obtained by driving a 2-inch, split-barrel sampler an d conducting a standard penetration test (SPT). The SPT is perfom1ed in general accordance with the procedures outlined in ASTM D 1586 and involves using a 140-lb drop hammer to drive a 2-inch, O.D. 7 ,_ Report of Geotechnical Study The Barracks Subdivision; College Station, TX standard, split-barrel sampler into the soils at the bottom of the borehole for three successive 6-inch increments. The vertical travel of the hammer is 30 inches. The number of blows required to drive the sampler over the depth interval from 6 to 18 inches is defined as the standard penetration number (N). However, if a limiting blow count of 50 blows is reached during any 6-inch interval, the test is terminated and an N-value of 50 is recorded along with the corresponding penetration in inches. Test termination also occurs if a total of l 00 blows has been applied or if the sampler has not advanced after l 0 successive hammer blows. The types of samples and the corresponding depths at which samples were collected, as well as results of any field tests such as the N-values determined for the SPTs, are presented at referenced depth intervals on the individual logs of borings in Appendix A. 2.3 GROUNDWATER OBSERVATION As previously discussed, the borings were drilled utilizing dry rotary auger drilling techniques so that the presence of groundwater could be observed both during drilling operations and immediately following completion of those operations. Groundwater observations were also made in the borings on the day following the initial drilling of the boreholes. The groundwater observations are discussed in Section 4 of this report. Subsequent to the final groundwater observations, all of the boreholes were backfilled with borehole cuttings and bentonite following the last groundwater observation as a safety precaution for pedestrian and workman traffic that might traverse the drilling sites. 2.4 BORING LOGS A field engineer was present during the field exploration to describe the subsurface stratigraphy and to note obvious anomalies in the subsurface stratigraphy that may have been present at specific boring locations. Descriptions of the subsurface conditions encountered at the thirty-one (31) boring locations are shown on the individual boring logs presented in Appendix A of this report. Note that the recently placed fill soils in the former ponds at the site are highlighted with light gray shading on the logs of boring. The "Key to Symbols and Soil Classification" sheet explaining the tem1s and symbols used on the logs are presented immediately following the logs. The logs represent CSC's interpretation of the subsurface conditions based upon the field geotechnologist's notes together with engineering observation and classification of the materials in the laboratory. The lines designating the interfaces between various strata represent approximate boundaries only, as transitions between formations may be gradual. 8 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX 2.5 SAMPLE CUSTODY All samples of subsurface materials obtained in the borings were removed from the samplers and visually classified in the field. Representative samples were sealed in appropriate packaging and placed in core boxes for transportation to the laboratory for further analysis. The samples will be stored for at least 30 days following the date of this report. At the end of the 30-day storage period, the samples will be discarded unless a written request is received from the owner requesting that the samples be stored for a longer period. 9 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 3.0 LABO RA TORY TESTING PROGRAM Samples of subsurface materials recovered from the borings were examined and classified by the geotechnical engineer. Various laboratory tests were then assigned for selected samples. The laboratory tests were performed to aid in soil classification and to determine the engineering characteristics of the foundation materials. The laboratory test results are presented in a summary tabular form in Appendix B and some of the test results are also presented both numerically and symbolically on the boring logs in Appendix A. 3.1 CLASSIFICATION AND MOISTURE CONTENT TESTS Laboratory tests were performed in order to classify the foundation soils in accordance with the Unified Soil Classification System (ASTM D 2487) and to determine the soil-moisture profile at the boring locations. The Atterberg limit determinations consisted of the Liquid Limit test and the Plastic Limit test and were perfonned in general accordance with the procedures outlined in ASTM D 4318. In addition to the selected Atterberg limit tests, grain-size distribution tests were also performed. The distribution of the particle sizes larger than 75 µm (the particle size retained on the U.S. Standard No. 200 sieve size) is typically determined using various sieve sizes. However, the percent of soil particles passing the U.S. Standard sieve size No. 200 (ASTM D 1140) was the only determination made on the recovered samples. The soil fractions passing the No. 200 sieve size are the silt-and clay-size particles and are generally referred to as "fines." The natural moisture content of individual samples was determined m accordance with the procedures outlined in ASTM D 2216. 3.2 STRENGTH TESTS AND UNIT DRY WEIGHT DETERMINATIONS Emphasis was also directed toward an evaluation of the strength or load-carrying capacity of the foundation soils. Strength tests were performed to develop an estimate of the undrained cohesion or c- value of the soils. The unconfmed compression test (ASTM D 2166) was performed in the laboratory on undisturbed samples of cohesive soils to determine the compressive strength characteristics. The unit dry weight of the samples was also detennined for each unconfined compression test sample in accordance with the procedures outlined in ASTM D 2166. JO Report of GeotechnicaJ Study The Barracks Subdivision; College Station, TX In addition, hand or pocket penetrometer tests were also performed both in the field and in the laboratory on relatively undisturbed soil samples. The hand or pocket penetrometer tests provide only an approximate indication of the unconfined compression strength of the soils. Experience with similar soil conditions in the vicinity of the proposed project ha s indicated that the hand penetrometer tests tend to overestimate the unconfined compression strength of the soil samples. 11 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 4.0 SITE CONDITIONS 4.1 GENERAL SURFACE CONDITIONS Currently, the site of the Barracks Subdivision can be described as undeveloped property that is in the process of being developed into an urban residential subdivision with paved streets and utilities. The planned improvements for the subdivision in the form of roadway subgrades, drainage system elements, and utilities were being constructed at the time of the field investigation. However, no residential structure construction had been initiated at the time of our field investigation. Prior to the recent initial development of the proposed subdivision, the site could be classified as a cornn1ercial facility that consisted of approximately 45 shallow ponds that were used to grow various aquatic plant species. The referenced ponds essentially covered approximately 80% of the surface area of the site. The draining and backfilling of these ponds was an important consideration for present and future development of the site. At the time of the present geotechnical study, mass grading of the site had been essentially completed and utility installations were being initiated for the subdivision. The ground surface is relatively flat with a slight slope from northeast to southwest. 4.2 GENERAL SUBSURFACE STRATIGRAPHY The subsurface stratigraphy at the boring locations drilled across the area of the proposed subdivision is shown in detail on the individual boring logs in Appendix A. The descriptions and classifications used to describe the stratigraphy followed the general guidelines of the Unified Soil Classification System (USCS, per ASTM D 2487), as discussed in the following Section 4.2. l of this report. A general and idealized description of the stratigraphy present at the various boring locations along the aligrunent is presented in Section 4.2.2 of this report. 4.2.1 Classification System Used in Subsurface Descriptions The soils comprising the foundation soils across the area of the proposed subdivi sion were generally classified in accordance with the criteria set forth in the Unified Soil Classification System (USCS, ASTM D 2487). Classification of the soils was primarily based upon test results derived from the laboratory testing of the various soils strata comprising the subsurface stratigraphy. The laboratory- performed classification tests consisted of determining the percent "fines" of the soils and of determining the Atterberg limits of the soils. The percentages of fines, i.e., the silt-and clay-size particles, were measured by determining the percentage of soils that would pass through or be "finer than" the No. 200 12 Report of Geotechnical Study The Barracks Subdivision; College Station, TX U.S. Standard sieve size. The openings in the No. 200 sieve are approximately 75 µm (microns) which roughly corresponds to the smallest size soil particle that can be seen by the "naked" eye (i.e., unaided by a microscope). The particles that are retained on the No. 200 sieve are referred to as granular soils and consist of sands and gravels. Thus, the portion of the sample that does not consist of fines represents granular soils, typically sands. Soils with a percent fines content of 50 percent or greater would classify as clays or silts under the USCS. Conversely, by definition, sands and/or gravels would have a percentage of fines of less than 50 percent. Sands are designated by the letter S under the USCS and modifiers such as M or C are used to designate silty sands (SM) or clayey sands (SP), respectively. "Pure" sands are given the designators W and P to represent well graded sands (SW) or poorly graded sands (SP). The Atterberg limit tests are cumulatively defined as consisting of the liquid limit (LL) test and the plastic limit (PL) test, along with the shrinkage limit test. Only the more common LL and PL tests were performed as part of the classification testing of the present study. These limits distinguish the boundaries of the several consistency states of plastic soils. The LL represents the moisture content at which the soil is on the verge of being a viscous fluid (i.e., a "very wet" condition), and the PL represents the moisture content at whjch the soil behaves as a non-plastic material (i.e., a "slightly moist" condition). The plasticity index (PD of soil is defined as the range of moisture contents at which the soil behaves as a plastic material and is defined as the difference between the liquid limit and the plastic limit (LL -PL = Pl). The magnitude of the PI of a soil is typically considered to be an indication of the clay content and the volumetric change (shrink-swell) potential of the soils (although the volumetric change can also vary with the type of clay mineral and the nature of the ions adsorbed on the clay surface). 4.2.2 General Description of Subsurface Stratigraphy The soil stratigraphy at the 31 boring locations across the proposed subdivision site is presented in detail on the individual boring logs in Appendix A. Each boring log should be consulted for a detailed description of the stratigraphy at a particular location on the site. In general, the stratigraphy present at the boring locations across the site was significantly variable throughout the 15 feet depth of exploration and particularly in the upper portions of the stratigraphy where the former ponds were located. As a result, there are important differences in soil types and soil strength, compressibility, and volumetric stability characte1istics with respect to horizontal distances across the site (i.e., between boring locations) and also with respect to vertical distances (i.e., depth at any particular boring location). A generalized stratigrapruc profile, consisting of three (3) zones has been developed for the deep foundation borings that were situated in areas that were not associated with the backfilling of former ponds. These include the borings designated as B25 through B3 l . Each of the three zones is described in general terms in the following separate subsections of this report. 13 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 4.2.2.1 Surficial Zone. The surficial zone, which was defined to extend from the ground surface to an average depth of three (3) feet, consisted of brown to dark brown clayey sands, and of red to brown lean clays. The results of the laboratory classification test performed on the samples of surficial soils obtained from the borings indicated a percentage of fines of ranging from approximately 32.8 to 56 . 7 percent. Since "fines" are defined as silt-and clay-sized particles, the percentage of soil that is not "fines" represents the sands (and sometimes gravels) in the sample. Thus, the tested samples indicated a variable percentage of sands ranging from 43.3 (I 00 percent -56.7 percent fines= 43.3 percent sands) to 67.2 percent (100 percent -32.8 percent fines= 67.2 percent sands). The Atterberg limjt tests performed on the samples in the surficial zone indicated LL values ranging from 24 to 39, with corresponding PI values ranging from 9 to 22. The soils of the surficial zone would therefore classify as either SC or CL type soils under the uses. The results of the pocket or hand penetrometer tests performed on the soils of the surficial zone were used to estimate the consistency, i.e., strength categorization, of the clay soils. The consistencies were estimated to be in the firm to stiff range. The relative density of the clayey sands of the surficial zone was estimated to be loose. 4.2.2.2 Intermediate Zone. The intermediate zone was defined as extending from immediately below the surficial zone at a depth of 3 feet to the top of the basal zone soils at approximately 8 feet depth. The soils of the intermediate zone were variable in character and ranged from red and gray to red and brown in color. The results of the laboratory classification tests performed on the clays of the intermediate zone indicated LL values ranging from 48 to 65, with corresponding PI values ranging from 29 to 44. The percentage of fines was measured to be in the range of 51 .5 to 80.6 percent and therefore represented a wide range of sands of 19 .4 to 48.5 percent. The clays therefore classified as CL or CH type soils under the uses. Hand or pocket penetrometer tests were performed on the soil samples of the intermediate zone to determine the consistencies of the clays which were estimated to be in the range of stiff to very stiff. 4.2.2.3 Deep or Basal Zone. The soils of the deep or basal zone were encountered below a depth of approximately 8 feet and extended to the maximum exploration depth of 15 feet below the existing surface grade. The soils of the basal zone were very similar to the soils of the overlying intermediate zone but were typically tan to light brown in color. The laboratory-performed classification tests indicated that the percentages of fines in the soils of the deep zone were in the range of 54.5 to 80.5 percent, which corresponded to a percentage of sands in the range of 19.5 to 45.5 percent. The LL values measured in the laboratory testing program ranged 14 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX from 54 to 62 and corresponding PI values ranged from 35 to 41. The soils of the deep or basal zone classified as CL or CH type soils. The results of the hand or pocket penetrometer tests performed on the soils of the basal zone indicated that the consistencies were in the range of stiff to very stiff. 4.2.3 Limitations of Stratigraphical Descriptions It should be noted that the previously generalized stratigraphical descriptions are presented as conceptual depictions of the subsurface conditions at the specific boring locations on the site, and variations from these generalizations may exist between the boring locations. Subsequent recom- mendations presented in this report for the design and construction of proposed structures and roadways are intended only for conceptual design purposes since they assume that the previously described gen- eralized conditions are continuous throughout the areas under consideration. Should conditions during construction be found to vary from the generalization, CSC should be notified in order to evaluate the potential effect of the variation on the recommendations presented in this report. 4.3 SUBSURFACE WATER CONDITIONS As previously discussed, the borings were advanced using dry rotary auger drilling techniques to the maximum 15 feet depth of exploration. The boreholes were monitored for groundwater levels both during and immediately following completion of drilling activities. No groundwater was observed in any of the boreholes during the drilling operations or immediately following completion of the drilling operations. All of the boreholes were allowed to remain open and were observed for indications of water levels on the day following drilling in order to obtain short-term groundwater information. Groundwater levels were observed in several of the open boreholes after the time lapse of approximately 24 hours following drilling. The observed groundwater levels are presented on the individual logs of borings presented in Appendix A. The indicated groundwater levels likely represent localized perched zones of water that are seasonal in nature and are probably not associated with significant water bearing zones. The boreholes were subsequently filled as a safety measure following completion of the 24-hour groundwater observations and longer term groundwater level readings could not be obtained. It is important to recognize that groundwater elevations may vary seasonally. Groundwater levels can be affected by such factors as the following: precipitation; infiltration; evapotranspiration; water levels in drainageways or ponds on a site or adjacent to a site; dewatering operations on adjacent sites; construction and post-development site drainage schemes; etc. The amount of precipitation occurring in the period immediately prior to construction is especially important. Groundwater levels at the time of construction may vary from those measured at the time of the field study. The groundwater levels are important since they have the potential to influence construction operations. Furthem1ore, it should be 15 Report of Geotechnical Study The Barracks Subdivision; College Station, TX understood that the groundwater conditions that were observed during the perfonnance of this short-term study were obtained to evaluate possible impacts on construction activities and should not be considered a comprehensive assessment of long-term groundwater conditions at the site. If the long-term variation of the groundwater level is critical to some design aspect of the proposed townhome structures, an extended and comprehensive assessment of groundwater conditions should be undertaken to better define the pertinent conditions that may influence the design. 16 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX 5.0 ANALYSIS AND RECOMMENDATIONS 5.1 GENERAL FOUNDATION ANALYSIS The primary considerations in the design of a safe and economical foundation system for a structure are the shear strength and related bearing capacity of the foundation elements, the compressibility (and related foundation settlement) characteristics of the foundation soils, and the vo lumetric stability of the foundation formations. The soils throughout the subsurface stratigraphies indicated at the 18 foundation boring locations consisted of clays of moderate to high plasticity. In general, the strength and compressibility characteristics of these clays within the stratigraphy appeared to be adequate to provide bearing support of the loads associated with typical one-story residential foundation systems without excessive settlements. However, some site preparation and verification of the adequacy of the foundation soils will be necessary in the former pond locations. A detailed discussion of these activities is presented in Section 8 of this report. In addition, the potential volumetric stability and associated potential for shrink-swell movements of the clay foundation soils in this geographical region must also be considered in the design of any foundation system. A discussion of the potential shrink-swell movements that could occur in the foundation soi ls is presented in the following section of this report. 5.2 GENERAL CONSIDERATIONS -POTENTIAL VOLUMETRICALLY ACTIVE FOUNDATION SOILS AND ALTERNATE TYPES OF FOUNDATION SYSTEMS As previously discussed, a majority of the soils throughout the subsurface stratigraphies at the boring locations across the site typically consisted of strata of clays of moderate to high plasticity. Soils with high clay contents have the potential to experience significant volumetric changes (i.e., shrink-swell movements) with variations in soil moisture content. The variations in soil moisture content that produce the shrink-swell movements are assumed to occur within a depth range below the ground surface known as the "zone of seasonal moi sture change." Although the extent of this zone of seasonal moisture change can vary with several factors, the depth of moisture variation in the geographical region of the project site is typically assumed to extend from the existing ground surface to a depth in the order of 8 to 10 feet below the existin g ground surface. Consequently, the greater the thickness of higher plasticity soil s within the zone of seasonal moisture change in the upper 10 feet of the stratigraphy, the greater will be the potential magnitudes of shrink-swell movements. Conversely, in those areas of a site where low 17 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX plasticity soils are present in significant thicknesses within the zone of seasonal moisture change, the potential magnitudes of shrink-swell movement will be lower. As a result, some movement should be expected for any shallow foundation system element founded within a stratigraphy composed of these moderate to high plasticity soils. The shrink-swell movements which could occur may produce deflections and differential movements in foundation systems, which, if not accounted for in the design phase of the project, could result in unacceptable distress to the supported structure in the form of excessive masonry, drywall, or slab cracking, and possibly even instability of the structure. 5.3 MAGNITUDES OF POTENTIAL SHRINK-SWELL MOVEMENTS 5.3.1 Calculation of Magnitudes of Potential Total Shrink-Swell Movements for Existing Soils Stratigraphy Calculations were performed to estimate the shrink-swell movements, sometimes referred to as the potential vertical rise (PVR). The calculations included considerations of the plasticities, the existing and potential future moisture contents, and the anticipated overburden pressures of the surface and near- surface zone soils at the subject site. The calculations performed for the present study were based upon a modified procedure developed by McDowell as outlined in Texas Department of Transportation (TxDOT) Test Method TEX-124-E. Based upon the existing soils stratigraphy at the site, a potential total PVR in the range of approximately 1.1 to 2.3 inches was computed for the soils. The potential vertical movements are significant with respect to the design of an adequate foundation system for the proposed townhomes. The major portion of the movement is attributable to the higher plasticity clays in the upper portions of the stratigraphy, i.e., within the surficial and near-surface zones of the stratigraphy. The magnitude of the potential movements can be significantly reduced if some of these higher plasticity soils are excavated from building areas and replaced with compacted, select fill soils with a lower potential for movement. If it is desired to reduce the potential vertical movement of the surface and near-surface clay formations through the excavation and replacement technique for individual townhomes, then borings performed for individual lots should be used to determine the depth at which excavation and removal will be most compatible with planned foundation systems for the individual townhomes. 18 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 5.3.2 Potential Differential Shrink-Swell Movements The magnitude of the vertical displacements due to volumetric changes in the surface and near- surface clays and sandy clays may vary across a building area and project site and will depend upon several factors, including the following: ( 1) the subsurface stratigraphy at a particular location; (2) the existing moisture condition of the subsurface materials at the time of construction; (3) the magnitude and source of any changes of the moisture regime in the residential structure areas following completion of construction; ( 4) the depth of removal of any existing moderate to high plasticity soils at the site; and (5) the thickness of new fill, if any, placed on the site. Due to these potential variations in conditions across the site, the potential differential movements due to shrinking or swelling of the foundation soils may be as large as approximately 7 5 percent of the predicted total vertical movements. Due to the localized area of the potential variations, the differential movements could occur over horizontal distances as short as 5 feet. 5.4 TYPES OF FOUNDATION SYSTEMS CONSIDERED AND SUPERSTRUCTURE DETAILING 5.4.l Use of Shallow Foundation System and Risk of Distress Associated with Potential Shrink- Swell Movements of Foundation Soils We understand that the developer has a preference to support the proposed townhomes of the subdivision on a shallow foundation system. The shallow foundation system will essentially consist of a subgrade-supported slab that is referred to as a slab-on-grade. The previously cited ranges of potential vertical movements of the foundation soils are significant and should be considered in the preliminary design of the shallow foundation system for the proposed townhomes. The slab-on-grade will have to be significantly stiffened and reinforced to accommodate the stresses associated with potential vertical movements that occur with shrinking or swelling of the foundation soils. We anticipate that this stiffening and reinforcing will be accomplished by the use of a conventional "waffle" type slab that employs numerous crossing grade beams to stiffen the slab. We also anticipate that the "waffle" slab will be designed in accordance with the Building Research Advisory Board or B.R.A.B. procedures for a Type ill slab. Therefore, recommendations are provided in the following sections of this report for design of the proposed foundations in accordance with the B.R.A.B . design procedures. 19 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 5.4.2 Inherent Risks of Distress Involved with Shallow Foundation Systems The recommendations presented in this report may be used for the conceptual design of foundation systems that may be able to tolerate anticipated foundation movements without excessive distress or structural fa ilure of the foundation systems or supported structures, provided that the foundation systems are adequately designed. However, the developer and designer as well as the owners of the residential structures should understand that there are risks involved with the use of a shallow foundation system even if the recommendations presented in this report are followed. As previously stated, any shallow foundation system founded in a stratigraphy which is composed, even in part, of moderate to high plasticity clays, would be susceptible to distress in response to shrink-swell movements of the foundation soils, as would the residential superstructure supported on such a foundation. The distress to the foundation system is typically manifest in the form of cracking of the concrete foundation elements, i.e., the beams or the slab. The distress to the superstructure is typically evidenced in the form of cracking in exterior masonry veneer walls and interior sheetrock walls, jamming of windows and/or doors due to distortion of the frames, and cracking of floors or dislodgment of sensitive floor coverings such as tiles. This cracking is likely to occur especially around door and window openings that represent "weak areas" in the wall systems. The extent of distress that can be tolerated in a residence is somewhat subjective. For example, some owners consider the patching of drywall cracks a part of the normal maintenance of a residential structure, while others consider such cracking to be unacceptable. It is almost impossible and typically impractical to eliminate all cracking of a structure in this geographic region if that structure is supported on a shallow foundation system in a stratigraphy with moderate to high plasticity clay soils. Consequently, prospective homeowners should understand the potential limitations of the use of a shallow foundation system. If the developer, designer, and owner wish to reduce to the maximum extent possible the risk of foundation movement and related distress, and if the owner is willing to pay the attendant foundation cost required to achieve such a risk reduction, then the developer and designer should consider the use of a deep drilled pier foundation system supporting a structural suspended floor system in such situations. In summary, it should be understood by all parties that the use of a shallow foundation system involves some risk related to foundation movement and possible building distress, especially if the foundation system is not properly designed to accommodate the predicted movements. The owner and designer should anticipate that some foundation movements wi ll occur and that some distress in both the foundation system and the supported building superstructure is possible. 20 Report of Geo technical Study The Barracks Subdivision; College Station, TX 5.4.3 Measures to Reduce Risks of Distress Involved with Shallow Foundation Systems The severity of any foundation or building distress associated with a shallow slab-on-grade foundation system could be appreciably reduced if the previously described excavation and replacement technique is incorporated in site development plans. The grading scheme for the building pad would include excavation of the upper zone of existing volumetrically unstable soils and the replacement of these excavated soils with more volumetrically stable select fill soils. There should be coordination between the structural design engineer and the site development engineer to ensure that the anticipated magnitudes of foundation movement used by the structural engineer conform to those associated with the grading plan developed by the site engineer. The foundation system used for the townhomes should be designed to accommodate the stresses produced by the potential shrink-swell movements that are associated with the site grading plan finally selected. The final grading plan may incorporate the excavation of various depths of existing soils and replacement of the excavated soils with select fill soils. The owner and designer should review the recommended site grading options and select the option that is most compatible with the owner's and designer's performance expectations for the structure and the project construction budget established by the owner. In addition, we highly recommend that measures be taken whenever practical to increase the tolerance of the proposed residential structures to post-construction foundation movements. The potential effects of foundation soil movements on sensitive architectural features of the proposed townhomes, such as exterior entryways, glass walls or windows, or interior block walls, should be considered in the design phase of the proposed structures. The superstructure and architectural elements of the proposed buildings should be designed to accommodate the predicted movements, wherever possible. For example, brittle architectural elements that could readily exhibit distress, such as exterior stone or brick walls, should be avoided, if possible, and more flexible materials such as wood exteriors or isolated masonry panels used in lieu of continuous masonry walls. If continuous masonry walls have to be used in a structure, there should be frequent jointing of the walls, especiall y above doorways and around windows and other wall openings to allow for some potential movement along the joints without cracking of the masonry features. Similarly, jointing of interior dry walls above door and window openings and the use of slip joints between dry wa ll panels should be considered. The use of movement-sensitive floor coverings, such as ceramic tiles should be avoided. If such tiles must be used, then geotextile reinforcement layers for floor tile bedding or underlayment layers should be incorporated into the construction plans. Finally, the slab should be stiffened and have added reinforcement at locations of right angles in the slab layout or at re-entrant corners where foundation stresses associated with foundation movement will be concentrated. Finally, the use of flexibl e plumbing connections can help reduce potential leakage frequently associated with slab movements. 2 1 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 6.0 SPECIFIC FOUNDATION RECOMMENDATIONS FOR SHALLOW FOUNDATION SYSTEMS -CONVENTIONAL WAFFLE SLAB (B.R.A.B. TYPE III SLAB) 6.1 GENERAL A conventionally reinforced and stiffened shall ow foundation system, which is sometimes referred to as a B.R.A.B. Type ill slab, may be used to transfer the loads from the proposed townhome structures to the foundati on soils. The shallow foundation system is expected to consist of continuous footings that will be integrally cast with a subgrade-supported floor slab. The parameters subsequently presented for the above design conditions are based on criteria published by B.R.A.B. The B.R.A.B. method is essentially an empirical design technique and the parameters provided are based on interpretation of the project soil borings and criteria published in the B.R.A.B. design manual. Pertinent B.R.A.B. design procedure values as well as supplemental recorrunendations that may be used in the preliminary design of conventional shallow foundation systems for the proposed townhomes are presented in the following subsections of this report. 6.2 MINIMUM FOOTING FOUNDING DEPTHS AND FOUNDING FORMATIONS We anticipate that the slab will have grade beams to carry linear loading bearing wall loads. The grade beams will also stiffen the slab foundation to help resist excessive stresses induced by foundation soil movements. The grade beams will essentially function as continuous footings. We recorrunend that the footings be fo unded at a minimum depth of 2.5 feet below the final surface grade at the location of each townhome structure. We have assumed that the top of the grade beams will extend a minimum of approximately 6 inches above the final site grade so that the total depth of each grade beam will be at least 3 feet. Soils at the recorrunended founding depths are expected to consist of either natural soils or of compacted select fill soils if the previously discussed excavation and replacement scheme is used at the site. Based upon the stratigraphy encountered at the boring locations, we anticipate that the soils present within the near-surface zone of the stratigraphy at the recommended 2.5 feet founding depth will consist of either a loose to medium dense brown clayey sand or a firm to stiff, red and brown lean clay. These natural soil s should provide adequate foundation bearing support for the shallow slab grade beams or footings. 22 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 6.3 MINIMUM FOOTING WIDTHS AND MAXIMUM ALLOW ABLE BEARING VALVES The grade beams or continuous footings should have minimum base widths of 16 inches. These minimum base widths of the foundation elements are recommended to reduce the potential for punching or puncture type shear fai lu re of the foundation soils due to the concentration of loads over an excessively small bearing area. The continuous footings should be proportioned based upon recommended unit net allowable bearing pressures for two loading conditions: ( 1) sustained loading; and (2) maximum or total loading. The sustained loading condition refers to the combination of dead load plus continuously applied live load. The maximum or total loading condition refers to the combination of dead load, live load, wind load, seismic load, or any other building code specified load which would produce the largest foundation contact pressures. We recommend that the unit net allowable bearing pressures presented in the fo llowing Table 1 for the two indicated loading conditions be used for the preliminary design of the footings at the indicated boring locations. The recommended net allowable bearing pressures incorporate factors of safety with respect to the theoretical ultimate bearing capacities of the footings . A minimum factor of safety of 3 was used for sustained loading conditions and a minimum factor of safety of 2 was used for maximum load conditions. The width of the grade beam footings should be proportioned in accordance with the more critical of the two loading conditions. It should be noted that these bearing pressures are not applicable for the existing soils that were in the areas of former ponds. Activities that should be pursued in these areas prior to the use of the referenced allowable bearing pressures are presented in Section 8. 6.4 POTENTIAL FOOTING MOVEMENTS Potential footing movements could occur either due to settlement of the footings as clays consolidate under applied structural loading or due to shrink-swell movements of the clays present within the upper portion of the stratigraphy. Each source of potential movement is discussed individu ally in the following two subsections. 23 Report of Geotechnical Study The Barracks Subdivision; College Station, TX Table 1. Recommended Unit Net Allowable Bearing Pressures for Shallow Continuous Footings (Grade Beams) RECOMMENDED NET LOCATION ALLOW ABLE BEARING PRESSURE Note 2 ON SITE FOUND-' pounds per square foot (WITH ING DESCRIPTION OF FOUNDING Sustained or RESPECT TO DEPTH, FORMATIONS Maximum BORING feet Note 1 or Total Continuous LOCATIONS) Loading Loading Factor of Factor of Safety of2 Safety of 3 B-25 through 2.5 feet Varies from stiff to firm brown clayey 6,000 psf 4,000 psf B-31 sand or red and brown lean clay Notes: I. Founding depth is referenced to surface grade existing at the time of the geotechnical field investigation. 2. Recommended allowable bearing pressures were rounded down to the nearest I 00 pounds per square foot (psf). Total Shrink-Swell Movements. The total shrink-swell movements that could be experienced by the shall ow, conventional slab-on-grade fo undation systems at the site correspond to the previously calculated PVR values of 1.1 to 2.3 inches. Total Settlement. Footing movements attributable to settlement as cohesive soils consolidate under applied structural loading may occur and should be considered in the design phase of the project. Anticipated total settlement s under the continuously applied structural loading are not expected to exceed one (I) inch in the areas that are not associated with former backfilled ponds. Settlements will be reduced if the actual magnitudes of applied loads are less than the previously stated assumed magnitudes of sustained or continuous loads. Differential Shrink-Swell Movements or Settlement. Due to possible variations m the characteristics of the near-surface foundation soils and in moisture conditions that develop following construction as previously discussed in Section 5.3.2, the potential differential movements due to ei ther settlement or shrink-swell movement may be as high as 75 percent of the predicted total movements and could occur over a horizontal distance in the order of 5 feet. 6.5 OTHER B.R.A.B. DESIGN VALVES Other design va lues listed in the B.R.A.B. design manual method are the following: • Climatic rating • Design plasticity index 24 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX • Soil support index The Climatic Rating (Cw) is a geographical value. We recommend that a Cw value of 22 be used for the proposed subdivision site. The design PI value will vary with the nature of the subsurface stratigraphy present at a particular structure location across the site. In addition, the PI value is typically "weighted" in recognition of the likelihood that the soils present in the upper portion of the stratigraphy will have more influence on foundation performance than the soils present in the middle portions of the stratigraphy. Similarly, the soils present in the middle portion of the stratigraphy will influence foundation behavior more than the soils present in the lower portion of the stratigraphy. This described methodology was used to compute "weighted" PI values for the soils encountered at the foundation borings at the site. The results naturally varied for the different types of soils and the different characteristics of the soils present at the numerous boring locations across the site. However, for preliminary design purposes, computations for an average PI value were performed for an idealized stratigraphy of soils created from the soils encountered at the different boring locations. The results of those computations indicated that an average design PI value of 36 may be employed in the preliminary design of foundation systems at the site. However, the average PI value to be used in the final design of any foundation system may be determined from an individual boring performed at the specific location of the foundation system on the site. The soil support value will depend upon both the climatic rating and the PI value. We recommend that the soil support value of 0.82 be used for the preliminary design of foundations at the site. 25 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 7.0 PAVEMENT RECOMMENDATIONS 7.1 GENERAL DESIGN CRITERIA USED FOR PAVEMENT ANALYSES The American Association of State Highway and Transportation Officials (AASHTO) design procedure was used to compute pavement thickness requirements for the residential street and minor collector streets of the proposed subdivision. The anticipated traffic loads and the load-carrying characteristics of the subgrade soils were used to determine required constructed thicknesses for either a rigid pavement section with a PCC surface course over a chemically-stabilized subgrade soil layer, or a flexible pavement section with an HMAC surface course over a constructed base section, or a full depth HMAC section. Results of the laboratory testing program were used as inputs into the pavement analysis to represent the load-carrying capacity of the existing sub grade soils which are anticipated to be modified by chemical stabilization. The following sections of the report present the design factors used in the analysis and also offer the resulting pavement design recommendations. 7.1.1 General Considerations of Subgrade Support for Pavement Systems General As previously described, the soils present within the upper portion of the stratigraphy which are expected to represent the sub grade soils for the pavement sections consist of both clayey sands and clays of moderate to high plasticity. These soil conditions were evident in both the backfill areas of the former ponds and in areas that were not subject to past backfilling activities. Recommendations concerning subgrade preparation of the roadway section and placement of fill soils (if necessary to achieve final design grades) are discussed in more detail in Section 8. Subgrade Soil Properties Assumed in Design The sub grade support characteristics of the anticipated sub grade soils were established based on correlations between soil classification test indices and soil support values, such as California Bearing Ratio (CBR) and resilient soil moduli (MR). CBR and MR support values are typically low for clays of moderate to high plasticity. Such clays will likely represent a significant percentage of the sub grade soils anticipated for the project. Conversely, clayey sands typically exhibit comparatively hi gher soil support values as compared to the moderately to hi ghly plastic clays. 26 Report of Geotechnical Study The Barracks Subdivision; College Station, TX The soil classification indices of the existing soils at the site were determined by laboratory tests. The classification properties of the fill soils that are recommended for construction of the roadway system as discussed in greater detail in a subsequent section of this report are defined as part of the fill material recommendations. The classification test results were compared to similarly classified soils for which soil support values have previously been developed. The referenced soil support values were previously determined for soils both in a "natural" condition and for a condition representative of chemical stabilization and compaction. For example, natural clays of high plasticity or CH type soils can be correlated with a CBR value of 2. If the clays are processed, chemically stabilized with hydrated lime, and compacted to a specified compaction effort, the CBR value has been measured to increase to a range of 6 to 8 or greater. Current design of pavement systems is typically related to the MR and not the CBR value. Research by the Corps of Engineers indicates that there is a correlation between the CBR and the MR of subgrade soils and that that relationship can be represented by the following equation: MR = 1,500 x CBR value However, independent research performed by state agencies as part of the AASHTO pavement study indicates that a more representative strength relationship can be expressed by the following equation: MR= 800 x CBR value The more conservative relationship developed by the state agencies was used to develop anticipated strength characteristics for the subgrade soils. The lowest CBR value determined from previous studies of chemically stabilized and compacted natural soils was used in the equation. As previously indicated, based upon the soil classification test results for the natural or unstabilized soils encountered at the boring locations within the subdivision and for the specified type of imported select fill soils, it is likely that the subgrade soils for the proposed subdivision streets will consist of clayey sands or clays of moderate to high plasticity. These soils are typically readily stabilized with hydrated lime as discussed in more detail in Section 8 of this report. Chemical stabilization and compaction of the clay subgrade soils will provide a relatively strong subgrade soil support value. In addition, chemical stabilization of the subgrade clay soils will help to somewhat reduce the relatively high shrink-swell potential of the medium to high plasticity clay soils within the zone of treatment at applicable locations along the project area. Consequently, we have assumed that all of the subgrade soils will be chemically stabilized and compacted to a minimum depth of at least 6 inches. A soil support value commensurate with chemically 27 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX stabilized and compacted subgrade soils was used in the design assumptions for the proposed roadway pavement sections. More specifically, a CBR value of 6 was chosen for design to represent the chemically stabilized and compacted clay subgrade soils. The MR corresponding to the CBR value of 6 for the chemically stabilized subgrade soils was conservatively determined to be approximately 4,800 psi. Further recommendations concerning stabilization of the subgrade soils, which includes the recommended type of stabilizing agent(s), are presented in Section 8.6 of this report. 7.2 PROJECTED TRAFFIC VOLUMES AND CHARACTERISTICS The traffic volume used in the pavement design for the proposed subdivision was based upon the general classification of the proposed subdivision roadways as residential and minor collector streets. The assumed projected traffic volumes that are associated with these street classifications were discussed in Section l of this report. The characterization of the vehicles that are believed to comprise the traffic using these streets was also presented in Section 1. The information outlined in Section l was used to determine the number, types, and loadings of the vehjcles assumed to be representative of the traffic that will use the planned subdivision. The loading for all the different types of vehicles that may travel over the paved surfaces is typically expressed in tenns of a "unit" single axle load. The unit term is known as the equivalent 18 kips single-axle load, or ESALs. ESALs provide a means of expressing traffic loading from numerous types of vehicles with various axle configurations and loadings in terms of unit 18 kips single-axle loads. Thus, every vehicle, no matter what the axle loading, can be expressed as a number of 18 kips equivalent single-axle load units. For example, passenger cars with single-axle loads of I kip can have an ESAL of 0.00018, whereas a large truck with a single-axle loading of 20 kips can have an ESAL of 1.51 . The traffic loading for the present project was calculated using the previously discussed traffic conditions, the subgrade strength properties (assuming that the subgrade soils will be chemically stabilized), and assumed typical paving material strength properties and reliability factors. The ESALs were computed for a 20-year design period based upon the estimated ADTs and other traffic characteristics listed in Section 1. The ESALs were calculated for both rigid and flexible pavement sections. 7 .3 PAVEMENT THICKNESS REQUIREMENTS The indicated traffic loading conditions and anticipated pavement section material properties were used in conj unction with the minimum pavement system layer thickness requirements outlined in the 2008 Bryan/Co llege Station Unified Design Guidelines for Streets and Alleys to determine if the minimum pavement sections presented in the referenced design guidelines for both rigid and flexible 28 Report of Geoteclmical Study The Barracks Subdivision; College Station, TX pavement systems would be sufficient to support the anticipated traffic loading conditions. Other minimum design standards such as those outlined in The Asphalt Institute's publication entitled Asphalt Pavements for Highways & Streets -Thickn ess Design, Manual Series No. I (MS-I) (1981), were also reviewed. The following tables present the results of our analyses. The pavement section layers described in the following tables represent recommended minimum layer thicknesses and material types for each of the various courses or layers of the respective pavement section. Table 2 presents the recommended pavement thickness for a conventionally reinforced rigid pavement section with a PCC surface course for residential and minor collector streets planned for the proposed subdivision. Table 2. Pavement Thickness Schedule for Rigid Pavement System Composed of PCC for Residential and Minor Collector Streets Planned for the Proposed Subdivision Residential Streets Minor Collector Streets Material Description Thickness (in.) Thickness (in.) 6.0 7 .0 i, iJ J_~~jnf~~c-~-c!~~~~E~te s~r.X~-~~-~-~urs~-=---___ ----------·l 1-----------6:6 _________ -·------------6:6________ -I Chemically-stabilized and compacted subgrade soils i t 3 j i-----12-.o-·-·-·-----f--··--·---·-------Tio--------:To-·t·-a-I-_c_o_n_s __ t_r_u--c-·t--e-d_p_a_v_e·-~~~-;-~-bi-c~~~~------------·-·< Notes: I. The design section for entrances to adjoining property driveways and tie-ins to intersecting city and state roadways may differ from those presented in the table, and should be established based on applicabl e requirements. 2. Concrete assumed to have a minimum modulus of mpture (as detennined in a third point beam loading test) coITesponding to 650 psi (approximately equivalent to concrete with a 28-day compressive strength of 3,500 to 4,000 psi). 3. The requirements for compaction and chemical stabilization of the subgrade soils are presented in Section 8 of the repo1t. Table 3 presents the pavement thickness recommendations for a multi-later flexible pavement system composed of a surface course of HMAC and an underlying crushed rock base course layer for residential and minor collector streets planned for the proposed subdivision. 29 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX Table 3. Pavement Thickness Schedule for Flexible (HMAC) Pavement Section with Crushed Rock Base Course for Residential and Minor Collector Streets Planned for the Proposed Subdivision Residential Streets Minor Collector Streets Material Description Thickness (in.) Thickness (in.) . . -------~: -·---·-·-~·· .. ._,.______ ------·--···········-··-----·----------------' ! 2 I 2.5 1,.0 J_1 HMAC (Item 340) TYQe D 2 , 1---·-----·---····-·-------··------r-----··-··---··--····---····-·---·---.. ····---··---·--······· .. -···----·----------·----------, I 6.0 I 8.0 I Compacted crushed limestone base (Item 247), Type A, ! L__________ _ _________ J______ i Grade I 3 I l-------~.:9 ________ r-------==~-==:~~Q_ ::·~~~~-~:-==J~gE~mically-=-st~_bifl~~~-~~~E~!i?P.i~~~i~~i[.~_e s~}_!~~~ =-~J I 14.0 I 16.5 I Total constructed pavement thickness Notes: I. The design section for entrances to adjoining property driveways and tie-ins to intersecting city and state roadways may differ from those presented in this table and should be established based on applicable requirements. Tie-in sections may be required to be const111cted of rigid pavement. 2. The Item reference corresponds to the const111ction details presented in lhe Texas Depattment ofTranspo1tation's (TxOOT's) Standard Specifications for Construction and Maintenance of Highways, Streets and Bridges (SSCM HSB), June I, 2004. 3. The base course should be compacted to at least 95% of the maximum density achievable in the Modified Proctor Moisture-Density (Compaction) test (ASTM D 1557). 4. The requirements for compaction and chemical stabilization of the subgrade soils are presented in Section 8 of the repo1t. Table 4 presents the pavement thickness recommendations for a full depth hot-mix asphaltic pavement section for residential and minor collector streets planned for the proposed subdivision. Table 4. Alternate Pavement Thickness Schedule for Flexible (HMAC) Pavement Section with Full Depth HMAC for Residential and Minor Coll ector Streets Planned for the Proposed Subdivision Residential Streets Minor Collector Streets Material Description Thickness (in.) Thickness (in.) I !;--· 2.0·-----····--····--2.s···--------T-J.ThiAc (Item 340) Tvne n2______________ ------------------, ~--~=-_--_4._0 ...... --... ------==--+-----~~~~_i ---;-:o ·---~-lt~~-34~1'~13-2·:·------:=:~==~:--~=:===~=~ i _____ i_9___ _ _______ §_~Q ________ +f hem1cally-stab1hzed and _~<?I.11.l?_acte~_::;-~~&!:_ade ___________ j 12.0 13.0 i Total constructed pavement thickness I Notes: I. The design section for entrances to adjoining prope1ty driveways and ti e-ins to intersecting city and state roadways may differ from those presented in th is table and should be established based on applicable requirements. Tie-in sections may be required to be constructed of rigid pavement. 2. The Item reference co1Tesponds to the construction details presented in the Texas Depa11ment of Transportation's (TxDOT's) Standard Specifications for Construction and Maintenance of Highways, Streets and Bridges (SSCM HSB), June I, 2004. 3. The requirements for compaction and chemical stabilization of the subgrade soils are presented in Section 8 of the repo1t. 30 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX All of th e types of pavement sections listed in Tables 2 through 4 are assumed to have a subgrade layer composed of chemically stabilized and compacted soils in accordance with the requirements outlined in Section 8. The character of the potential roadway subgrade soils is expected to be variable along the routes of the proposed roadways. In particular, the strength, compressibility and shrink-swell characteristics of the fill soils placed within the limits of the former ponds is expected to be significantly different from the natural soils located between the ponds and outside of the pond areas. Consequently, we strongly recommend that consideration be given to the use of the rigid PCC pavement section rather than the HMAC section. Our recommendation is also based on the desire to limit the anticipated extent of reflective cracking that will likely result due to the high variability of soil moduli associated with the backfilling of the fom1er ponds. Should the developer select the HMAC option, provisions should be made to perfonn periodic maintenance to seal reflective cracks that will occur during the life of the HMAC pavement and the possible need for an overlay ,to account for small magnitudes of differential settlements. Tie-ins to existing streets or highways should be made in accordance with the sections presented in the previous tables or applicable city/state design criteria, whichever is more stringent. All of the conventionally reinforced concrete paving should be reinforced with steel reinforcing bars to minimize temperature and shrinkage cracking, to discourage widening of any cracks that may form, and to aid in transferring loads across joints. We recommend that the conventionally reinforced concrete paving be reinforced with a minimum of No. 4 bars spaced at 16 inches on center in the longitudinal direction and No. 4 bars spaced at 16 inches on center for the transverse direction. In addition, adequate jointing of the conventionally reinforced concrete pavement should be included in the design and construction of the pavement system. Conventionally reinforced concrete pavement should be segmented by the use of control joints placed a maximum distance of 15 feet each way. Keyed and doweled longitudinal joints should be located in all street sections greater than one lane (10 to 13 feet) in width. Expansion and/or construction joints should be placed at a maximum spacing of 200-foot intervals. Expansion joints should not be placed through the middle of area inlet boxes in the pavement. Isolation joints should be placed between the pavement and all existing or perm anent structures (such as drainage inlets). All joints should be sealed with Sonobom Sonolastic SLl (or equivalent) to minimize infiltration of surface water to the underlying sub grade soils. The edges or periphery of the pavement secti on are a natural weak point du e to the lack of edge support beyond the paved area. Parallel cracks in the pavement section along the edge of many paved areas are a common indicati on of partial edge failure. Some provision for support of the edge of the paved areas should be included in the current design plans. The most common means of edge support is a 31 Report of Geotechnical Study The Barracks Subdivision; College Station, TX ~ PCC curb and gutter, although a thickened edge of pavement has also been employed. We recommend l}! that the exterior boundary of the chemically-stabilized subgrade layer extend at least 2 feet beyond the tJ1 Gdge of the pavement surface lay~These extensions will help to minimize the formation of edge cracks \ tJwu"0 in the pavement system due to either a lack of boundary support under wheel loading as previously r discussed or due to shrinking of subgrade soils away from the outer edge of the pavement during dry weather and the subsequent loss of subgrade support. 7.4 PAVEMENT SYSTEM MAINTENANCE 7.4.1 Pavement Drainage The control of surface and groundwater is a critical factor in the performance of a pavement system. Adequate surface and subsurface drainage provisions should be included in the pavement design scheme. Drainage provisions may include the following, among other things: a steeply graded pavement surface to rapidly transport stormwater runoff to collection or discharge points; an adequate number of stormwater catch basins or curb inlets in the paved areas to capture the stormwater in an expeditious manner; and adequately sized stonnwater sewer piping or open channel drainage ditches to promptly transport the collected stormwater to discharge points in drainageways away from and preferably down- gradient from the roadway. Finally, landscaping or "green" areas such as medians requiring extensive irrigation and other potential sources for moisture infiltration within the limits of the street reconstruction area should be minimized, if at all possible. 7.4.2 Pavement Maintenance The developer should institute and budget for a regular maintenance program for the paved areas until such time as maintenance of the roadways is turned over to the City of College Station. Regular pavement maintenance is a prerequisite for achieving acceptable performance levels over the anticipated life of the pavement system. Cracks occurring in the surface course of the pavement should be sealed as soon as they occur in order to minimize stormwater infiltration into the underlying pavement system layers and subsequent degradation of performance. Sealants that can withstand exterior exposures, such as Sonobom SL-1 for rigid pavement sections or rubberized asphalt sealants for flexible pavement sections, should be considered for these purposes. A periodic inspection program should be conducted to identify the formation of cracks, eroded areas, and other indications of pavement distress, such as ruts, pot holes, areas of ponded water, etc. The need for possible repair should be anticipated over the expected life of the pavement system. 32 - Report of Geotechnical Study The Bai-racks Subdivision; College Station, TX 8.0 CONSTRUCTION CONSIDERATIONS General construction recommendations for the proposed project are offered in the following subsections for consideration. These items should be considered "minimum standards" and are intended to be used in conjunction with project specifications. 8.1 SITE PREPARATION -CLEARING AND SUBGRADE PREPARATION In order to reduce the potential detrimental effects on the proposed residential structures and pavement systems, existing surface vegetation, organic matter, and topsoils should all be removed from proposed building pads or proposed paved areas (including residential driveways). The removal of the vegetation should include all roots, including the major root systems associated with large trees, as well as any desiccated soils present within the root "bulbs" of the trees. Special attention should be directed to the removal of any existing organic materials or "muck" that may be present within former drainage swales, ponds, or depressions on the site. The vegetation and all "mucked-out" materials should be removed from the site. The excavated topsoil may be stockpiled for later use in landscaping areas that are not planned for future structures and roadways. As previously mentioned, the project site originally supported a series of shallow ponds that were drained and backfilled prior to the initiation of our study. It is our understanding construction quality assurance (CQA) testing was not conducted during the backfilling of the referenced ponds. The absence of such documentation will necessitate moisture/density testing to ensure compliance with City specifications and to minimize consolidation 0£ backfill soils beneath the roadway under anticipated traffic loading. In addition, the documented depths of these ponds are within the anticipated founding depth of the shallow foundation systems for the townhomes. Accordingly, CSC has developed recommendations for site development procedures that should be followed to promote the load support capabilities of the foundation soils beneath the roadways and townhomes. Basically, we anticipate that two (2) types of "structural" areas will be included as part of the proposed development scheme. One of these areas will consist of previously backfilled areas within the right-of-ways of the residential street network throughout the proposed subdivision, and the second area will consist of the planned building pads beneath the town110me foundations. The recommended activities should be pursued as part of site development and include the following: 33 --.. --- Report of Geotechnical Study The Barracks Subdivision; College Station, TX Right-of-Ways {or Residential Streets ~ield moisture/density tests should be conducted on the pavement foundation soils located within General Parkway, Sergeant Drive, Corporal Road, and Alley 3 (betwet;!J,1 Corporal Road and Sergeant Drive) at 200-foot intervals. The tests should be taken at the top of native soil subgrade (not lime stabilized section), and at six-inch depth intervals to a final depth of 3 feet below the bottom of the proposed lime-stabilized subgrade section. The moisture/density tests should be compared to the City specifications -relative to placement of subgrade soils beneath roadways. CSC recommends that the moisture specification be extended to -Jo/~OMC<+4% (pending City concurrence) due to the variable nature of the fill soils. If all density tests meet the required specifications, the exposed subgrade soils should be proof- rolled to identify any areas of weak subgrade soils between test locations. The proof-rolling should be conducted with equipment that, when loaded, has a gross vehicle weight of at least 20 tons. Any soft or weak spots or areas of organic materials or pumping soils, such as wet silts or fine sands, that are identified during proof-rolling should be removed to firm ground and replaced with compacted structural fill as outlined in Section 8.3. In the event that moisture/density tests indicate an unsuitable backfilled section, the existing unsatisfactory soils should be removed within the ROWs, reprocessed for moisture control and removal of objectionable materials, and tested in accordance with applicable City specifications. The material -should be reprocessed in a continuous manner horizontally within the ROWs, rather than at individual pond locations. This procedure will help minimize reflective cracking that may result from differences in soil moduli at the vertical interface between the natural soils between the pond locations and the backfill soils placed within the ponds. Foundation Support Soils Information developed during the geotechnical study indicated that the soils at several of the boring locations beneath the townhomes consisted of loose to medium dense silty sands. These so'i'ls may exhibit poor load-bearing characteristics with increased moisture contents, such as could occur after periods of heavy and/or prolonged precipitation. In addition, soils with high percentages of fines may be ., difficult to compact if they are in a very moist to wet condition at the time of construction. Surficial clayey sands or si lty sands that are underlain by clay formations have a tendency to trap rainwater and to "pump" when compacted. Pumping refers to the condition when the energy applied during the compaction of the soils is transferred into the relatively incompressible water trapped within the clayey or silty sands and not to the soil structure. Thus, the compaction energy is "absorbed" by the wat& within 34 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX the void spaces of the soil structure and not by the soil structure itself. As a result, the soil structure undergoes little or no densification under the applied energy of compaction. Rather, the compaction energy is transferred laterally within the water mass to produce a "wave" in the soils that resembles a "water bed" effect. In addition to the aforementioned concerns, these silty, granular type soils may not remain stable during the excavation of exterior and interior grade beams that are associated with shallow foundation systems. Specifically, the lack of cohesion that is inherent to silty sands, particularly if they are very dry or very moist at the time of construction, will tend to promote sloughing of these granular soils into open beam excavations and will potentially compromise the integrity of the foundation. Based on the presence of these soils at multiple townhome locations, it is recommended that the upper 12 inches of existing soil beneath each townhome be stripped and stockpiled to evaluate the existing integrity of the underlying founding soils. The exposed subgrade soils should be proof-rolled to identify any areas of weak sub grade soils within the footprint of the townhomes. The proof-rolling should be conducted with equipment that, when loaded, has a gross vehicle weight of at least 20 tons. If the proof-rolling activities indicate the presence of any soft or weak spots or areas of pumping soils, the existing backfill soils should be removed to firm ground and replaced with compacted structural fill as outlined in Section 8.3. If the unsuitable soils are left in place and become wet and unstable, a ground- supported foundation slab could experience some movement due to the weak and compressible character of these surficial soils. The residential building pads should be of uniform thickness. Thus, on sites with sloping ground surfaces, the excavation of existing soils may have to be deeper in the "uphill" portions of the proposed building area in order to create a level surface prior to fill placement. In addition, the subgrade in the building pad area should be firm and should provide uniform support of the foundation system. The sub grade soils across the building pad should be compacted to a density in the range of 95 to l 00 percent of the maximum dry density achievable in the Standard Proctor Moisture-Density Relationship (Standard Proctor) test (ASTM D 698) at moisture contents in the range of the optimum moisture content (OMC) to 4 percent above the OMC, inclusive. Compaction characteristics of the fill should be verified by in-place density tests. The tests should be performed at an average rate of one test for every 2,000 ft 2 of building pad subgrade plan area, but not less than three (3) tests per building pad. Uncontrolled fill soils and/or unsuitable materials that are not removed and remain beneath new buildings and paved areas could result in excessive settlements and produce distress to the proposed structures or the pavement sections. Additional testing (borings, test pits, etc.) and evaluation may be required if any such materials are encountered during construction. 35 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 8.2 SITE PREPARATION -DRAINAGE AND MOISTURE CONTROL Stormwater generated by development of the project should be managed to ensure that precipitation runoff is not routed to townhome locations and does not pond in the residential structure areas. Rather, the collected stonnwater should be routed away from the locations of the proposed townhomes into existing or established stormwater drainage systems. The contractor should implement a stormwater management plan early in the construction process both for the subdivision as a whole and for individual townhome pad locations across the site. Site grading plans should include the elevation of the townhome building pads a signjficant height above the surrounding ground surface elevations so that final grades around the structures can be established to promote stormwater flows away from and around the perimeter of the structures. We recommend that the ground surface around the townhome structures be sloped at downward grades of least 5 percent for a horizontal distance of at least 10 feet from the face of the townhomes to assure positive drainage away from any structure. Furthermore, we recommend that the stormwater collected from the gutters and downspouts of the roofs of the completed townhome structures be routed through "tight-lined" piping attached to the end of the downspouts. The "tight-lined" piping should discharge either directly to the underground storm sewer system, to paved driveway areas, or to established drainage swales some distance away from and hydraulically down-gradient from the residential structure locations. We also recommend that trees or plantings requiring irrigation waterings not be placed in any landscaped areas immediately surrounding the proposed townhome structure locations. These plantings can serve as additional sources of moisture loss (tree root systems) or gain (landscape waterings) in the foundation soils. Any trees in the building areas should be planted at a minimum distance away from the buildings equal to the height of the mature tree. Provisions should be made to the maximum extent possible to discourage utility trenches from serving as potential pathways for water to migrate from outside to beneath the townhome building pad areas. Sloping the bottom of the utility trench away from the building pads and the use of anti-seep collars (such as thin, vertical "sheets" of compacted clay) should be considered. It is critical to foundation perfonnance that an adequate stormwater management system be designed and installed around the areas of individual townhomes to discourage the ponding of moisture at the building locations both during construction and during the life of the structures. Inadequate site preparation has been associated with numerous distressed building foundations in this area since the slab- on-grade foundation systems are supported directly on the subgrade soils. 36 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 8.3 BUJLDING AREA ("SELECT") FJLL AND GENERAL PAVEMENT AREA FJLL MATERIAL SELECTION AND PLACEMENT PROCEDURES We anticipate that fill materials may be placed in two distinct areas of the site as part of planned site development operations. One of these fill placement areas will be in the proposed building pad and is hereinafter referred to as "select" fill soils. The other area of possible fill placement is within that portion of the roadway ROWs that is planned to be paved. The fill material that is placed in the planned paved areas is referred to as general pavement area fill (and NOT as "select" fill). Select fill placed in the building areas or used to construct the building pad is also sometimes referred to as structural fill. Select or structural fill in the building pad area should meet the following criteria with respect to material properties: • Fill material which is placed beneath the proposed structure for the purpose of replacing excavated material or for elevating final site grades should consist of a low-plasticity material that classifies as either a clayey sand (SC type soil under the USCS) or a very sandy clay (CL type soil under the current USCS) with a PI between 10 and 20, inclusive, and in addition should have a maximum LL value of 38. The minimum plasticity is established so that purely granular soils are not used as select fill. The small percentage of clays in the select fill required to achieve the minimum PI of 10 should help to discourage moisture from stormwater infiltrating into the soils of the building pad. ~ Fill placed in the areas to be paved is referred to as general pavement area fill and should meet the following criteria with respect to material properties: • Fill placed outside of the building pad area in areas planned to be paved may consist of low to moderate plasticity material that has PI values of between 15 and 30, inclusive, along with a maximum LL value of 49, inclusive. The fill materials should generally classify as SC or CL type soils under the USCS. Both types of fill materials should meet the following material requirements and should be placed according to the following procedures: • • • Soils containing an excessive amount of silt (i.e., greater than approximately 20 to 25 percent) without a corresponding percentage of clays to "balance" the silts, should not be used for either "select" fill or for general pavement area fill. Soils classifying as ML, CL- ML, MH, OL, OH, SM or CH type soils under the USCS should not be used as fill. Compacti on of the fi ll soils should be at moisture contents in the range of 2 percent below the OMC to a maximum of 4 percent above the OMC, inclusive, and should be in lifts that do not exceed 6 inches in compacted thickness. The fill should be compacted to a density of at least 98 percent of the maximum dry density as determined by the Standard Proctor compaction test. Compacti on characteristics of the fill should be verified by in-place density tests. The tests should be performed on each 6-inch-thick lift at an average rate of one test for every 2,000 square feet of plan area for the building pad and one test for every 5,000 square feet of plan area for the paved portions of the project. A minimum of three (3) tests should be taken for each lift of fill. 37 Report of Geotechnical Study The Barracks Subdivision; College Station, TX 8.4 SHALLOW CONTINUOUS FOOTING EXCAVATIONS The following criteria should be followed during design and construction of the continuous footings: • • • The footings should be checked for size and inspected to ensure that all loose material has been removed prior to placement of the concrete. The side slopes of the footing excavations may slough into the open excavations, particularly if granular soils are present within the excavation depth. Any such fall-in should be removed from the excavation. The need for wooden forms to maintain the stability of the footing excavation should be anticipated. In addition, if the excavations occur during or immediately after periods of heavy rainfall, there may be problems with temporarily high or perched groundwater. The possible need for stormwater interceptor ditches, sumps, and sump pumps should be anticipated. Prompt placement of concrete into the footing excavation following completion of digging, cleaning, placement of reinforcing steel, and inspection of the excavation, is strongly recommended. Precautions should be taken during placement of the reinforcement and concrete to prevent any loose excavated soil from entering into the excavation. Any clods of earth that slump into the footing excavation during concrete placement should be promptly removed. Under no circumstances should a footing be excavated that cannot be filled with concrete before the occurrence of a significant rainfall event that could flood the footing excavations and result in the creation of a weak saturated soil layer on which the footings will be supported or the collection of eroded soils across the bottom of the footing excavations. • The reinforcing steel placed in the footing should extend to no closer than 3 inches from the base or sides of the excavation as required by the American Concrete Institute (ACI). • Verification of the construction process and the dimensional characteristics of the footings should be performed as part of the project quality assurance (QA) program. 8.5 FOUNDATION CONCRETE Concrete used in the residential foundations should meet the following minimum requirements, among others: • • • • The concrete used for the construction of all foundation elements should consist of a mix that has been shown to comply with the requirements of ACI 214 and ACI 301 , Section 3.9.2.l. Submitted mix designs should indicate that the aggregates have been tested in accordance with ASTM C 33 within a time period that does not exceed one year. If fly ash is used in the concrete, the replacement percentage should not exceed 20% of the total cementitious material. The foundation concrete should generally have a mimmum 28-day design compressive strength of 3,000 psi as determined in accordance with ASTM C 39, unless otherwise specified on the structural drawings. A test set of four cylinders should be cast during each placement of concrete at a rate of one set for every 75 yd3 of concrete placed with at least one set cast during each placement day. One cylinder should be tested fo r compression 38 Report of Geotechnical Study The Barracks Subdivision; College Station, TX ~8.6 • • strength at 7 days following placement and two cylinders should be tested at 28 days following placement. The fourth cylinder should be held in reserve pending the evaluation of the compression test results for the other three cylinders and may be either tested or discarded based upon the evaluation. Water may be added to the mix at the site by an experienced materials engineer in order to develop design workability, but only to the extent that the water/cement ratio does not exceed 0.55 lb/lb. An appropriate percentage of air entrainment admixture should be added to the concrete . PAVEMENT SUBGRADE SOILS STABILIZATION REQUIREMENTS The pavement design recommendations presented in a previous section were developed assuming that the various materials would comply with the material requirements and be constructed in accordance with the specifications listed below. The specifications include recommendations for chemical stabilization of the subgrade soils in the paved areas. If the subgrade soils in the paving area at the site are wet and not easily workable at the time of construction, the soils can also be chemically stabilized as a construction expedient. • A minimum depth of subgrade soil stabilization of 6 inches should be achieved. ,..,. • • We anticipate that the majority of J he_µ ement sub grade soils will consist of clays of moderate to high plasticif(l.e-., PI > 18). hese plastic soils should be stabilized with Type A hydrated lime ofT e C ·ck-b.me..-Eor preliminary planning purposes, the amount of lime to e added to the soils for purposes of stabilization can be estimated to be approximately~he percentage is measured with respect to dry soil unit weight. For example, for a subgrade soil layer of 6 inches in thickness that has a unit dry weight of approximately 100 pcf, approximately 27 lb/yd2 of hydrated lime should be used in the mixture. However, once final grades have been established and the soils that will comprise the subgrade layer identified, we recommend that specific "lime series" tests be performed to identify the optimum percentage of !ime to be mixed with the subgrade soils to achieve the de · %L_ '7 subgrade layer improvement. • Finally, some of e subgrade soils may consist of sands or silts of low plasticity 1.e. P < r = 7 . These subgrade soils should be stabilized with Class C fly ash at a rate of 12 percent as measured by dry weight of soil (54 lb/yd2 for a lift of 6 inches thickness). Alternately, a minimum of 4 ercent of T e I Portland cement can be used to stabilize the low cohesive soils. Specific stabilization tests should be 39 Report of Geotechnical Study The Baincks Subdivision; College Station, TX .. • • • performed in the laboratory to verify the assumed percentages of the stabilizing agent. Stabilization procedures should be in accordance with the previously referenced SSCMHSB Item 260, Lime Treatment for Material Us ed As Subgrade (Road Mixed), Type A Treatment specification, or Item 265 , Lime-Fly Ash (LFA) Treatment For Materials Used As Subgrade. Modifications to this specification should include a minimum of 48 hours of tempering time before final mixing, a minimum of 60% of the lime/soil mixture passing a No. 4 sieve before compaction, and a restriction against the use of carbide or byproduct lime. The stabilized layer should extend at least 2 feet beyond the curb or pavement edge . This extension of the stabilized area will assist in the formation of a moisture barrier and will help reduce moisture fluctuations in the underlying expansive soils. Compaction of the stabilized natural soils or the stabilized structural fill meeting the requirements presented h&ein should be at moisture contents within the range of the OMC to 4 percent above the OMC, inclusive. The compacted density of the fill soils should be at least 98 percent of the maximum dry density as determined by the standard Proctor compaction test, ASTM D 698. As previously indicated, the recommended percentages of lime, fly ash, and cement to be admixed with the subgrade soils should be confirmea by specific laboratory tests performed at the time of construction. 8. 7 PAVEMENT MATERIAL REQUIREMENTS The pavement materials should comply with the material requirements outlined in the current version of the joint 2008 BICS Unified Technical Specifications for Water, Sewer, Streets, and Drainage and in the previously referenced Texas Department of Transportation Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges (June 1, 2004). More specifically, the following pavement material types, properties, and placement procedures are recommended for the various pavement section materials. 8.7.1 HMAC Surface Course (Flexible Pavement Section) • The HMAC surface course should comply with SDHPT Item 340, Type D or Type B (for full depth asphalt pavements). Hveem stability, as detem1ined by ASTM D 1560, should be between 35 and 55 . 8.7.2 Base Course (Flexible Pavement Section) • The base course should consist of crushed limestone aggregate base that meets or exceeds the requirements of SDHPT Item 248, Type A, Grade I. Compaction of the base material should be at OMC to 4 percent above OMC (inclusive) and to 95 percent of the maximum dry density as detem1ined by the Modified Proctor Compaction Test, ASTM D 1557-78. 40 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX 8.7.3 PCC Surface Course • • • • • • The concrete used for the construction of all foundation elements should consist of a mix that has been shown to comply with the requirements of ACI 214 and ACI 301 , Section 3.9.2.1. Submitted mix designs should indicate that the aggregates have been tested in accordance with ASTM C 33 within a time period that does not exceed one year. If fly ash is used in the concrete, the replacement percentage should not exceed 20% of the total cementitious material. The concrete should have a minimum 28-day design compressive strength of 3,500 psi (per B/CS Unified Specification No. 150 -Concrete) as determined in accordance with ASTM C 39 or C 109. A test set of concrete cylinders which consists of a minimum of four (4) cylinders should be cast during each placement of concrete at a rate of one set for every 75 cu yd of concrete placed with at least one set cast during each placement day. One of the cylinders should be tested for compressive strength after a time lapse of 7 days and the other two cylinders tested after a time lapse of 28 days. The fourth remaining cylinder may be held in reserve pending the evaluation of the compression test results for the first three (3) cylinders. Water may be added to the mix at the site by an experienced materials engineer in order to develop design workability, but only to the extent that the water/cement ratio does not exceed 0.55 lb/lb. An appropriate percentage of air entrainment admixture should be added to the concrete that is exposed to the weather elements. 41 - Report of Geotechnical Study The Barracks Subdivision; College Station, TX 9.0 BASIS OF RECOMMENDATIONS The recommendations contained in this report are based, in part, on the project information provided to CSC. If statements or assumptions made in this report concerning the location and design of project elements contain incorrect information, or if additional information concerning the project becomes available, the owner should convey the correct or additional information to CSC so that CSC may evaluate the new infonnation and determine if the recommendations presented in the report will have to be modified. The field exploration, which provided information concemmg subsurface conditions, was considered to be in sufficient detail and scope to form a reasonable basis for the conceptual planning of the foundation systems of the proposed development. Recommendations contained in this report were developed based upon a generalization of the subsurface conditions encountered at the boring locations across the site and the assumption that the generalized conditions are continuous throughout the areas under consideration. However, regardless of the thoroughness of a subsurface exploration, there is always a possibility that subsurface conditions encountered over a given area will be different from those present at specific, isolated boring locations, especially when the presence of the existing ponds across the site of the proposed development is considered. CSC strongly recommends that experienced geotechnical personnel who understand the background of the project and the recommendations presented in this rep<?rt be employed to observe con- struction operations and to document that conditions encountered duriq~ construction confonn to the I I assumed generalizations that formed the basis for the recommendations presented in this report. In addition, the construction observers should document construction activities and field testing practices employed during the earthwork and foundation construction phase of the project. Questionable procedures and/or practices should be reported to the design team, along with timely recommendations to solve the issues raised by the procedures or practices. The Geotechnical Engineer warrants that the findings, recommendations, specifications, or professional advice contained herein have been made after preparation in accordance with generally accepted professional engineering practice in the field of geotechnical engineering in this geographic area. No other warranty is implied or expressed. 42 - I CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. APPENDIX A Figures Figure l -Project Vicinity Map Figure 2 -Site Plan and Plan of Borings Boring Logs Borings B-l through B-3 l Key to Terms and Symbols Used on Boring Logs 11 c s c L11g111cc1wg & L11111011111c111al Co11s11/ra11rs. Ille. Prepared For: GREENS PRAIRIE INVESTORS, LTD. ! I 2000 0 2000 FEET I PROJECT VICINITY MAP PROPOSED BARRACKS SUBDIVISION COLLEGE STATION, TEXAS PROJECT NO: 8139 LOCATION: COLLEGE STATION, TEXAS APPR: WRC REV. DA TE: -- DRAWN BY: WBC SCALE: AS SHOWN DATE: 9/26/08 FIGURE NO.: 1 LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DR Y AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION 8-1 Moisture Content, X DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 314.04 DEPTH TO WATER: SEE NOTES LABORATORY TESTS 0 20 40 12 14 16 18 20 CLAYEY SAND (SC), --with gravel 2-4' Gray CLAYEY SAND (SC) --tan from 6-8' Tan FAT CLAY (CH), with ferrous staining and sand seams --blocky from 12-15' TOTAL DEPTH 15 FEET NOTES: I. Borehole dry and caved lo 11.0 FEET after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. 17.2 45.6 23.8 46.2 40 23 1.9 96.7 11------ill 34.0 95.8 69 47 CSC Engineering & Environmental Consultants, Inc. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION B-2 Moisture Content, X DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 311.96 DEPTH TO WATER: SEE NOTES 0 20 2 12 14 16 18 20 Tan SILTY SAND (SM}, dry, (FILL) Brown and Gray SANDY LEAN CLAY (CL}, (FILL) Red and Gray SANDY FAT CLAY (CH) Tan FAT CLAY (CH}, wilh ferrous staining and sand seams --increasing sand seams and blocky 9.5-15' TOTAL DEPTH 15 FEET NOTES: I. Borehole dry and caved lo 13.0 FEET afler 24 hours 2. Shaded deplh lnlerval denoles approximale backfilled depth or former pond. 21.4 65.9 21.1 59.1 52 33 34.5 89.5 78 55 CSC Engineering & Environmental Con sultants, In c. LOG OF BORIN G PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION 8-3 Moisture Content, X DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 312.29 DEPTH TO WATER: SEE NOTES 0 20 2 14 16 18 20 Brown SILTY SAND (SM), dry. (FILL) Brown and Red CLAYEY SAND (SC), with small gravel fragments and clay pockets Tan FAT CLAY (CH), with ferrous staining and sand seams, blocky Tan CLAYEY SAND (SC), moist TOTAL DEPTH 15 FEET NOTES: I. Borehole caved lo 13.5 FEET, DTW = 12.75 FEET after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. 9.9 52.l 10.1 16.8 50.0 32 16 CSC Eng1neer1ng & En vironmental Consul tant s, Inc. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION : COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION B-4 Moisture Content. X DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 309.49 DEPTH TO WATER: N/A 0 20 12 14 16 18 20 Tan CLAYEY SAND (SC), dry, (FILL) Brown CLAYEY SAND (SC), with gravel Tan FAT CLAY with sand (CH). with ferrous seams and staining --blocky from 10-15' TOTAL DEPTH 15 FEET NOTES: I. Shaded depth Interval denotes approximate backfilled depth of former pond. 10.3 54.8 11.4 50.3 28 13 27.8 79.l 56 36 3.1 90.2 1----111 En91n eer1ng & En vironm ental Consultants, In c. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION B-5 Moisture Content. X DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 307.35 DEPTH TO WATER: SEE NOTES 0 20 16 18 20 Brown CLAYEY SAND (SC), (FILL) and Tan FAT CLAY with sand CLAYEY SAND (SC). FAT CLAY (CH). with ferrous staining and sand seams, blocky TOTAL DEPTH 15 FEET NOTES: I. Borehole caved to 8.5 FEET. DTW = 7.0 FEET after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. IO.I 48.0 46 28 12.5 25.7 71.5 60 39 31.6 68.3 54 35 CSC Engineering & En vi r onmental Consultants, Inc. tS LOG OF BORI NG PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION 8-6 Moisture Content. it DATE: SEPTEMBER 9, 2008 LOGGER: WR C SURFACE ELEVATION: 308.87 DEPTH TO WATER : SEE NOTES 0 20 40 12 14 16 18 20 SANDY FAT CLAY (CH), dry, Brown SILTY SAND (SC). dry, (FILL) --N=6 Red and Gray SANDY FAT CLAY (CH) Tan and Red SANDY LEAN CLAY (CL), with ferrous staining TOTAL DEPTH 15 FEET NOTES: I. Borehole caved to 9.0 FEET, DTW ; 8.0 FEET after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. 16.3 59.5 60 40 6.9 26.4 67.8 68 46 1.9 94.8 30.1 64.9 47 29 CSC Eng1neer1ng & Environmental Consultan ts, Inc. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION B-7 Moisture Conlenl. :< 0 20 12 14 16 18 20 CLAYEY SAND (SC). moist. Brown SANDY LEAN CLAY (CL). dry Red and Gray SANDY CLAY (CL). with ferrous staining and sand seams Tan FAT CLAY (CH), with ferrous staining and sand seams sand content from TOTAL DEPTH 15 FEET NOTES: I. Borehole caved lo 6.0 FEET. DTW = 5.5 FEET after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. 11.8 14.6 14.6 32.0 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 309.52 DEPTH TO WATER: SEE NOTES 48.0 33 17 50.4 26 11 86.4 67 46 CSC En91neer1ng & Environmental Con sultants, In c. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AU GER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION B-8 Moisture Conlenl. X DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION : 310.12 DEPTH TO WATER: SEE NOTES 0 20 40 2 4 6 B 10 12 14 16 18 20 CLAYEY SAND (SC), dry. (FILL} Tan FAT CLAY (CH), with ferrous staining and sand seams Tan SANDY FAT CLAY (CH), with ferrous staining --increasing sand seams from 10-15' TOTAL DEPTH 15 FEET NOTES: I. Borehole caved to 10.5 FEET. DTW = 10.0 FEET after 24 hours 2. Shaded deplh Interval denoles approximate backfilled depth of former pond. 10.l 6.2 33.1 94.4 71 49 27.6 72.2 54 34 CSC En gineering & Environmental Consultants, Inc. LOG OF BORIN G PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION 8 -9 Moisture Content. % DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 311.74 DEPTH TO WATER: SEE NOTES 0 20 12 14 16 18 20 FAT CLAY (CH), slightly moist, Tan and Brown FAT CLAY (CH) --ferrous staining and sand seams from 7-15' --thick ferrous seams at 14' TOTAL DEPTH = 15 FEET NOTES: I. Borehole dry and caved lo 14.0 FEET a fter 24 hours 2. Shaded depth Interval denotes approximate backfilled depth or former pond. 31.4 83.3 82 58 33.3 94.2 59 39 CSC En g1neer1ng & En vironmental Consul t ants, Inc . LOG OF BORING 8-10 PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DR Y AUGER TOTAL DEPTH: 15 FT 12 14 16 18 20 SOIL CLASSIFICATION F'AT CLAY (CH), dry, --N=6 --moist, soft from 3-5' Red and Gray F'AT CLAY (CH). slightly moist Tan SANDY LEAN CLAY (CL) --ferrous staining and sand seams inlerbedded from 9-15' --thick ferrous seams al 14' TOTAL DEPTH = 15 FEET NOTES: I. Borehole dry and caved lo 14.5 FEET after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth or former pond. Moisture Content. % DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 314.33 DEPTH TO WATER: SEE NOTES 0 20 40 4.3 29.9 3.9 89.2 CSC Engin eering & Environmental Consultants, Inc. LOG OF BORIN G B-11 PROJECT: THE BARRACKS SUBDIVISION DATE: SEPTEMBER 9, 2008 LOCATION : COLLEGE STATION, TEXAS LOGGER: WRC DRILLING METHOD: DRY AUGER SURFACE ELEVATION: 312.10 TOTAL DEPTH : 6 FT DEPTH TO WATER: SEE NOTES SOIL CLASSIFICATION LABORATORY TESTS ,... .§' ~~ .. 'd' J~ Moisture ~·0~ww~~ ~ .(} !-.." ~ <$-.... • ·~ ~ Content, X :,,,,. .. ,.. ~·~· ~ ~ 9: ~ '.">.. ~ :,,,,.~ <t<>:. ,{.f $'?~ 0 20 40 ~lif .:.§>'.::,~ ~~ ~rfc; ~~ ... ~ ~.§' ~ Brown CLAYEY SAND (SC}, with I I I I I I I ferrous staining, and clay pockets, ~ (FILL) 13.4 55.9 -2-------f--~ --with gravel from 2.5-4' -4-f------~ Light Brown SANDY LEAN CLAY (CL}, moist. with ferrous staining ~ 17.7 7.5 119.3 -6-f--f---- TOTAL DEPTH = 6 FEET -8 -----f-- -10-----f-- -12-f------ -14-f--f---- -16-f----f-- - -18-NOTES: ----f-- I. Borehole dry after 24 hours - - -20-----f-- - ~ ~ I I I I I I I I csc Engineering & Env1ronmen tal Con su I tan Es, Inc. I - - LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: ORY AUGER TOTAL DEPTH: 6 FT SOIL CLASSIFICATION 0 Brown SILTY SAND (SM). dry, (FILL) -2 -r-r- Brown CLAYEY SAND (SC), moist -·---~ ~ -6 -,.._._~-0---------------<- -8 - -10- -12- - -14- -16 - - - -18- - - -20 - - - - TOTAL DEPTH = 6 FEET NOTES: I. Shaded depth Interval denotes approximate backfilled depth of former pond. B-1 2 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 311 .59 DEPTH TO WATER: N/A I I I I I I I 10.4 31.8 --- ->-- 14.9 50.I ->--->--- ->--- ->-- ->-- ->----- ->--- ->--- -I I I I I I I CSC Eng1n eer1 ng & En viron mental Consultants, Inc. LOG OF BORI NG PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DR Y AUGER TOTAL DEPTH: 6 FT SOIL CLASSIFICATION Brown SANDY LEAN CLAY {CL). moist, (FILL) 0 -~ ~~~·~-== ~ -~ --with small gravel fragments from _ 2-4' ~--~ Light Brown SANDY LEAN CLAY (CL), with ferrous staining =~ >--6 ---~-"C..J."11-----------------l~ - -8- >-10---->-12---->-14--- -16- -18-- -20 - TOTAL DEPTH = 6 FEET NOTES: I. Borehole caved lo 1.5 FEET. DTW = 1.0 FEET after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. 8-1 3 Moisture Content, lt 20 I I I 15.4 10.8 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 308.86 DEPTH TO WATER: SEE NOTE S 40 I I I I 53.8 ->--- 53.1 34 17 ->----- ->--->--- --- ->-- ->-- ->--->--- ->--- ->--- I I I I I I I CSC En g in eering & En viron men t al Con sultants, In c. - LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 6 FT 8 10 12 14 16 18 20 SOIL CLASSIFICATION SILTY SAND (SM), (FILL) Brown SANDY LEAN CLAY (CL), moist --with pockets of gray clay TOTAL DEPTH 6 FEET NOTES: I. Shaded depth Interval denotes approximate backfilled depth of former pond. B-14 DATE : SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 308.05 DEPTH TO WATER: N/A 16.4 55.6 42 24 1.8 100.0 CSC Eng1n eer1ng & Environmental Consultants, In c . LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS 8-15 DATE: SEPTEMBER 9, 2008 LOGGER: WRC DRILLING METHOD: DRY AUGER TOTAL DEPTH: 6 FT SURFACE ELEVATION: 307.43 DEPTH TO WATER: SEE NOTES SOIL CLASSIFICATION ~ Brown FAT CLAY (CH). (FILL) I I I l l l l Brown CLAYEY SAND (SC), moist, 17.7 46.5 _ 2 -o---1-w~ with gmol (FILI.) _ _ _ 24 9 -t--- -...... -- _ 4 ___ ~ 1-T-a_n_a_n_d_R_e_d_S_A_N_D_Y_F_A_T_C_LA_Y_(C_H_)-. ---t >-- ~ with ferrous seams and sand seams ~ 30.2 71.2 60 40 1.7 aa.s.11----111 t-6 -!-----------------~>----- TOTAL DEPTH = 6 FEET -8-----t--- -10-----t--- t--- -12 -------t--- t--- t--- -14-...... -...... ------ -16-...... -L--t--- t--- t--- -18-NOTES: --L--t-- I. Borehole caved lo 2.0 FEET, t---DTW = 0.5 FEET after 24 hours 2. Shaded depth Interval denotes t--- approximate backfilled depth of - t-20-former pond. -----t-- t---- t---- t---I I I I I I I - I csc Engin eering & En v1ronmen tol Con sultants, In c . I LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 6 FT SOIL CLASSIFICATION 8-16 Moisture ConlenL. X DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 308.84 DEPTH TO WATER: N/A 0 20 8 10 12 14 16 18 20 LEAN CLAY Brown SILTY SAND (SM). (FILL) (CH). wilh ferrous SANDY LEAN CLAY (CL), wilh TOTAL DEPTH 6 FEET NOTES: I. Shaded deplh lnlerval denoles approximale backfilled depth of former pond. 14.3 53.4 37 20 2.3 106.2 17.7 58.6 32 16 CSC En91neer1ng & En vironmental Consultants, In c. LOG OF BORIN G PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TE XAS DRILLING METHOD: ORY AUGER TOTAL DEPTH: 6 FT -2 --- ~ r--4 ---~ ~ r--6 --- -8 - -10- -12 - >-14 - -16 -- -18 - -20 -- - SOIL CLASSIFICATION Light Tan SILTY SAND (SC), (Possible fill from 0 to 1.5') Tan SANDY LEAN CLAY (CL), with ferrous staining Red and Gray SANDY FAT CLAY (CH). with calcareous nodules --tan at 5.5' TOTAL DEPTH = 6 FEET NOTES: I. Borehole dry after 24 hours '-- - - - - - .___ .___ - - B-17 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 310.13 DEPTH TO WATER: SEE NOTES I I l I I I 12.7 54.4 -L- ---r--- 17.0 62.4 58 37 2.0 99.7 1-- 1-- --->--------------- ------ 1-- - ----- - - >------ ---.___ - 1-----.___ ----- 1-- -L--r--- 1-- 1--- -L-------I I I I I I I I csc Engin eering & En v1ron men t al Co n su I tan t s, Inc. I LO G OF BOR ING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 6 FT SOIL CLASSIFICATION B-18 Moisture Content, % DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 310.45 DEPTH TO WATER: SEE NOTES 0 20 8 10 12 14 16 18 20 SILTY SAND (SM). dry, (FILL) (SC), with CLAY (CL). with TOTAL DEPTH 6 FEET NOTES: I. Borehole dry after 24 hours 2. Shaded deplh lnlerval denoles approximate backfilled depth of former pond. 9.2 47.7 20.4 65.4 1.9 100.1 ...---, .. CSC Eng1neer1ng & Environmental Consu ltants. Inc. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION : COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 6 FT SOIL CLASS IFICATION = ~ Ton ond Rod CLAYEY 5'ND {SC), d'Y ~ : ~ -~ I--with gmol Imm 2.5-6 0 ~ --into'.b•dd•d <Joy mm• from ~ 4.5-6.0 r-6 -~,____ f'->-~-it--------------1t- TOTAL DEPTH = 6 FEET -10-f- r-- r-- r-- -12-- -14-- -16-f- -18-NOTES: -I. Borehole dry arter 24 hours -20-f- B-19 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION : 314.09 DEPTH TO WATER: SEE NOTES I I I I I I I 6.1 21.6 -f-- 15.3 51.3 31 15 -f-- ----- r-- ----- >--- r-- r-- ---f-- r-- >--- r-- ----- r-- >--- r-- -f---- r-- r-- >--- -f---- >--- r-- r-- I I I I I I I I csc Engineering & En vironmental Consul ton t s, Inc. I ... LOG OF BORING PROJECT: THE BARRACKS DEVELOPMENT (PHASE I and 11) LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: ORY AUGER TOTAL DEPTH: 6 FT SOIL CLASSIFICATION B-20 Moisture Content. X DATE : SEPTEMBER 9, 2008 LOGGER : WRC SURFACE ELEVATION: 311 .96 DEPTH TO WATER: SEE NOTES 0 20 SILTY SAND {SM), {FILL) Brown CLAYEY SAND (SC), (FILL) 4 -l~~-H-~.....,;~ ..... ,11 ..... ---------------i 8 10 12 14 16 18 20 Red and Gray CLAYEY SAND {SC) TOTAL DEPTH 6 FEET NOTES: I. Borehole dry after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. 14.5 46.6 21.4 48.l 52 32 CS C Engineering & Environm ental Consultants, Inc . .. LOG OF BORI NG PROJECT: THE BARRACK S SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: ORY AUGER TOTAL DEPTH: 6 FT SOIL CLASSIFICATION B-21 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION : 313.44 DEPTH TO WATER: SEE NOTES Moisture rff-. Content. ::t 11"" .. •• 0 20 40 q_"' <-,~ 8 10 12 14 16 18 20 with and Tan SANDY LEAN CLAY TOTAL DEPTH 6 FEET NOTES: I. Borehole dry after 24 hours 2. Shaded depth Interval denotes approximate backfilled depth of former pond. 13.6 62.9 40 23 10.6 55.5 43 25 CSC Eng1neer1ng & Envir onmental Con sultants, Inc . LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 6 FT SOIL CLASSIFICATION 8-22 Moisture Conlenl. X DATE : SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 311.08 DEPTH TO WATER: SEE NOTES LABORATORY TESTS 0 20 40 8 10 12 14 16 18 20 Gray SANDY LEAN CLAY (CL), with gravel, {FILL) Dark Brown LEAN CLAY (CL). with calcareous nodules TOTAL DEPTH 6 FEET NOTES: I. Borehole dry after 24 hours 9.9 54.3 30 14 17.6 66.0 45 27 2.2 107.4 CSC Engineering & Environmental Con sultants, Inc. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DR Y AUGER TOTAL DEPTH: 6 FT 2 4 8 10 12 14 16 18 20 SOIL CLASSIFICATION Tan SILTY SAND {SM), {Fill. from 0 -2.5') --with intermixed red clay from 2-3' TOTAL DEPTH 6 FEET NOTES: I. Borehole dry after 24 hours 0 B-23 Moisture Conlenl. X 20 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION : 306.86 DEPTH TO WATER: SEE NOTES LABORATORY TESTS 14.3 52.4 15.2 57.6 CSC Engineering & Environmental Consultant s, Inc. LOG OF BORING B-24 PROJECT: THE BARRACKS SUBDIVISION DATE: SEPTEMBER 9, 2008 LOCATION: COLLEGE STATION, TEXAS LOGGER: WRC DRILLING METHOD: DRY AUGER SURFACE ELEVATION: 306.26 TOTAL DEPTH : 6 FT DEPTH TO WATER: SEE NOTES SOIL CLASSIFICATION LABORATORY TESTS .... ~ " ~ l°d> c!~ Moisture )~f!J 0-~~~~~ ~ -~ "' ~ • .::b • ·~ ~ 90 q ....... .:;j Content, X ~ ~~ s ·;:: ~ :: ;;. S ........ ~ ..,~ ~"'-.rt .t,,,~ 0 20 40 Q.'ti ~~ .$'.:;,~ ~ ~ cj> c? ~~ _..c: t.;J'.§' Brown SILTY SAND {SM), (FILL) I I I I I I I 11.6 45.3 -2--._ --~ Brown CLAYEY SAND lSC), with - gravel, dry, (FILL) ~ -4-~ Red and Gray SANDY FAT CLAY (CH), ---._ - with ferrous staining ~ 24.6 65.6 59 38 2.1 92.3 --tan and gray al 5.5' -6------ TOTAL DEPTH = 6 FEET -8---._ --- -10-- -'----- -12------- -14-,_ ----- '--16-f--,_ --- -18-NOTES: --._ --- I. Borehole dry after 24 hours -20---'--------I I I I I I I I csc Engineering & En v1ronment:ol Con su I ton t s, Inc. I LOG OF BORIN G B-25 PROJECT: THE BARRACKS SU BDIVISION DATE: SEPTEMBER 9, 2008 LOCATION: COLLEGE STATION, TEXAS LOGGER: WRC DRILLING METHOD: DRY AUGER SURFACE ELEVATION: 305.97 TOTAL DEPTH: 15 FT DEPTH TO WATER: SEE NOTES SOIL CLASSIFICATION LABORATORY TESTS ,... ~J~~jl ~Cl ..!j ~ Moisture )/; ~"JJ 0 ~0~% ~ ~ .~ s~ f.J' e!.J-• .:b • ·~ ~ <::s ....... ~ Conlenl, X I ~" ~ ·~ ~ :: ~ ~ -~ .~ ~"' ~q_ ,,f .:f tf ">~ 0 20 40 q; <.,~ $'~~ .s:.f <J<:i :;;,"' .... ~~ ~ Red and Brown LEAN CLAY (CL). dry I I I l l I I ~ 23.0 56.7 39 22 -2 ------x ~ --N=14 Red and Gray SANDY LEAN CLAY (CL) -4 ------~ 22.3 62.3 48 29 -6 ~ ------ ~ -8 ------ I Tan and Brown SANDY LEAN CLAY -10 (CL), with ferrous seams I------- ~ -12---1-----~ --sand seams increasing al 13' -14-~ --------TOTAL DEPTH = 15 FEET >-16-----------18-NOTES: I---1------I. Borehole dry and caved lo 13.5 FEET after 24 hours ---20 -I---I-----,______ ,______ ,______ I I I I I I I -I csc Engineering & Environmental Consultants, Inc. I LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT ~ s ~,,_ 14 16 18 20 SOIL CLASSIFICATION SANDY LEAN CLAY {CL). dry --dark brown to brown from 3-4' Dark Brown and Red SANDY CLAY {CL). slightly moist --tan and brown with thin interbedded sand and orange ferrous seams from 7-9' --red and brown with thicker ferrous seams from 9-15' TOTAL DEPTH 15 FEET NOTES: I. Borehole caved lo 14.0 FEET, DTW = 14.5 FEET after 24 hours 0 8-26 Moisture Content, ~ DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION: 305.44 DEPTH TO WATER: SE E NOTES LABORATORY TESTS ~ .. 1;" ... ,. 20 40 q_~~~ 12.8 51.6 28 13 32.0 1.8 86.l CSC Engin eering & En vironmental Consultant s, Inc. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION , TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION 8-27 Moisture Content. % 0 20 2 4 6 12 14 16 18 20 Dark Brown CLAYEY SAND (SC) --clay conlenl increasing from 3-4 ' SANDY LEAN CLAY ferrous slaining and Tan SANDY LEAN CLAY (CL) --brown wilh orange ferrous slaining and sand seams from 9-15' --moist sand seams at 14' TOTAL DEPTH = 15 FEET NOTES: I. Borehole caved lo 10.0 FEET. DTW = 9.0 FEET after 24 hours 16.8 31.4 DATE: SEPTEMBER 9, 2008 LOGGER: WRC SURFACE ELEVATION : 307.19 DEPTH TO WATER: SEE NOTES 32.8 24 9 51.5 48 30 CSC Engineering & Environmental Consul tants, Inc. LOG OF BORING B-28 PROJECT: THE BARRACKS SUBDI VISION DATE: SEPTEMBER 10, 2008 LOCATION: COLLEGE STATION, TEXAS LOGGER: WRC DRILLING METHOD: DRY AUGER SURFACE ELEVATION: 307.63 TOTAL DEPTH: 15 FT DEPTH TO WATER: SEE NOTES SOIL CLASSIFICATION LABORATORY TESTS ~J~~r/ Moisture .. ,h w~;;~~w· ,.,"" f ~ <?~ Content. % ~::.."· ~·~· ~ ~ IS~~~ ·"-<:S·~· .. ~ ~-;;: cf:f ~rt 0 20 40 q_I ~.$! :.j'".::,1$ ~ ~ ~ i:f .::;,~ ... t: ~.§' ~ Dark Brown CLAYEY SAND (SC) I I I I I I I ,_______ t-- ,_______ Dark Brown SANDY LEAN CLAY (CL). 16.6 50.1 t-- dry t-- -2 >--->---1---~ t-- -26.3 76.4 65 44 t-- t-- -4 ~ Red and Brown SANDY FAT CLAY I--I---- (CH). moist t-- ~ -6 >---L--1---~ --thin interbedded sand seams 31.3 B0.6 51 32 from 7-9' -B >--->---1---~ Tan and Brown SANDY FAT CLAY (CH). with ferrous seams -10 I--I----~ -12-I--I----~ t-- -14-~ >---L---- ,___ ,___ TOTAL DEPTH = 15 FEET ,___ >-16->--->---1--- >------,___ ,___ >------ -18-NOTES: I-->---1--- I. Borehole caved to 13.0 PEET, >------DTW = 12.9 PEET after 24 hours >------ t-- -20-1---1---1--- t-- t-- t-- I I I I I I I I csc Engineering & Environmental Con su I tan ts, In c. I - LOG OF BORING B-29 PROJECT: THE BARRACKS SUBDIVISION DATE: SEPTEMBER 10, 2008 LOCATION: COLLEGE STATION, TEXAS LOGGER: WRC DRILLING METHOD: DRY AUGER SURFACE ELEVATION: 306.30 TOTAL DEPTH: 15 FT DEPTH TO WATER: SEE NOTES SOIL CLASSIFICATION LABORATORY TESTS .... .$ "- ~,~$r/ Moisture ~"fJ f~~0~%~VJ$ ~ ·~J1" :-...: ~ "'" ~ <.; ..p Content, X ~ .),..,. ;§'·~· :1':: !S'Cl. ~ ·~ ·~ ~~ ~<;, c.?i>J r/ cl 0 20 40 q_'fi e.,~ .:.::,t:>..:.::,IS' ~ .:/ cJ ~ ~~ ..,e: ;.$'.§' ~ Brown CLAYEY SAND. dry, (possible I I I I I I I fill} 1---- ~ Gray and Red SANDY FAT CLAY (CH} 30.0 83.4 1---- 1---- -2 ~ ------ 1----~ 19.3 55.4 57 37 ,_____ ,______ -4 ~ -..._ ---~ Red and Brown SANDY FAT CLAY (CH} ~ -6 ..._ -..._ --- ~ Tan and Brown SANDY FAT CLAY (CH}. with ferrous seams and sand -8 ~ pockets ------ 30.l 54.5 54 35 -10 ~ ..._ -~ --- ~ -12-..._ -~ --- ~ 1---- -14---moist sand seams al 14' ..._ -..._ ---~ TOTAL DEPTH = 15 FEET -16---L... -,_ - i------ i------ i------ -1a -NOTES: ----,_ - 1----I. Borehole dry and caved lo 13.5 I----FEET after 24 hours I---- 1----,._ -20----->-- ,._ I---- I---- I I I I I I I I csc Engin ee ring & En viron men Ea l Co n su l ton t s, Inc. I - LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLE GE STATION. TEXAS DRILLING METHOD: ORY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION 8-30 Moisture Content. :i: DATE: SEPTEMBER 10, 2008 LOGGER: WRC SURFACE ELEVATION: 308.48 DEPTH TO WATER: SEE NOTES 0 20 12 14 16 18 20 CLAYEY SAND (SC) Brown SANDY LEAN CLAY CL . dry, soft, N=9 Red and Brown SANDY CLAY (CH) Tan and Brown SANDY FAT CLAY (CH), with ferrous seams - -thicker ferrous seams at 13' TOTAL DEPTH 15 FEET NOTES: I. Borehole caved lo 13.0 FEET, DTW = 12.5 FEET after 24 hours 16.4 55.2 23.7 60.l 1.8 97.0 CSC En gineering & En vironmental Consultants, Inc. LOG OF BORING PROJECT: THE BARRACKS SUBDIVISION LOCATION: COLLEGE STATION, TEXAS DRILLING METHOD: DRY AUGER TOTAL DEPTH: 15 FT SOIL CLASSIFICATION 8-31 Mo is lure Content, :i: DATE: SEPTEMBER 10, 2008 LOGGER: WRC SURFACE ELEVATION: 312.43 DEPTH TO WATER: SEE NOTES 0 20 12 14 16 18 20 --increasing clay content from 3-6' FAT CLAY with sand Tan FAT CLAY with sand {CH) --blocky, thick ferrous seams and some sand seams from 10-15' TOTAL DEPTH 15 FEET NOTES: I. Borehole dry and caved lo 14.5 FEET after 24 hours 11.7 54.3 14.7 60.9 32.7 80.5 62 41 Engin eering & En vironmental Con sultants, Inc. - KEY TO SYMBOLS AND SOIL CLASSIFICATION Unified Soil Classification System (ASTM D 2487) SAMPLE TYPES COMPRESSIVE STRENGTH TESTS AND LABORATORY TEST DATA © -+ 0 6 Thin-Woll Tube Split-Borre! Rock Core Cone Disturbed Cuttings No Hond Torvone Unconfined Compression U-U w/Testoble Penetrometer Recovery Penetrometer Recovery Trioxiol Somple Major Divisions Group Symbols Typical Names ~ iii ~ .. iii Vl g _J N i5 ~ Vl c 0 0::. w 0: z ~ <( ~ Ct'.'. --' (.'.) ,!(? I o w ·~ Vl 0 Ct'.'. ::I <( 0 0 (.) ~ c 0 ::. 0 z c 0 Vl ::. _J i5 Vl N 0 .., 0 "'0 z 'Oz = c g ~ -(5 ~ l/l 0 :? SW Well-Groded Grovels, Grovel-Sond Mixtures, Lillie or No f'ines Poorly Groded Grovels, Grovel-Sond Mixtures, Lillie or No Fines Cloyey Grovels, Grovel-Sond-Cloy Mixtures Well-Groded Sonds, Gravelly Sonds, Little or No f'ines o.... c t> .f: (/)~ f!:. -~ ~; 1.i.. SP ::::::::. Poorly Graded Sonds. Gravelly o o ...J Ill U 0 :::::::.. Sands, Little or No Fines z ~ ;t ~1-----+-----++->'.r-' .. +-' ........ ..,, .. ,,.'_+----------------~ <{ ~ ~ .!! ~ In' (/) l/l ~ ~ -~ 5 .~.. 0 u.. c ~ ·2 0 ~~ : ~c e ~~ ~ .... V'l < Vl >-<( _J (.) "O c 0 Vl t-_J Vi "' "' ., --' 0 .--.:::' U") .~ c --' 0 .c 'O >--·:; a :::; SM SC ML CL OL MH CH OH ~:~::\_'\:: ~""'""-" «'\·'. I I I I I I I I I I I I I I I I Silly Sonds, Sond-Sill Mixtures Cloyey Sonds, Sond-Cloy Mixtures Inorganic Sills with Slight Ploslicity Inorganic Cloys of Low to Medium Ploslicily. Gravelly Cloys, Leon Cloys Organic Sills ond Organic Silly Cloys of Low Ploslicity Inorganic Silts, Micoceous or Diotomoceous f'ine Sond or Silty Soils, Elastic Sills Inorganic Cloys of High Ploslicity. f'ot Cloys Orgonic Cloys of Medium to High Ploslicily, Orgonic Sills HARDNESS CLASSIFICATION OF INTACT ROCK JO~ Finer -Percent Finer thon No. 200 Seive Relative Density of Coarse Strained Soils Penetration Resistance N Volue (Blows/Ft-) 0-4 4-10 10-30 30-50 Over 50 Oescriplive Term Very Loose Loose Medium Dense Dense Very Dense • Bosed on driving o split-borrel sampler with o 140 lb weight dropped 30 inches Soil Modifiers ~ 1111 CLAYEY SILTY SANDY Consistency Terms of Fine-Groined Soils Compressive Strength, qu (ton/sq fl) 0 lo 0.25 0.25 lo 0.50 0.50 to 1.00 1.00 to 2.00 2.00 lo 4.00 Over 4.00 Descriptive Term Very Soft Soll Firm Stiff Very Stiff Hord Groundwater Le vels '\7 -STATIC WATER LEVEL .... -HYDROSTATIC WATER LEVEL Rock Classification HARDNESS EXTREMELY HARD VERY HARD HARD son VERY son APPROX. RANGE OF UNIAXIAL COMPRESSION STRENGTH (P.S.1.) >13,900 6,940 -13,900 3,4 70 -6,940 1,740 -3,470 70 -1,740 I SILTSTONE SHALE CLAYSTONE LIMESTONE SANDSTONE COAL CSC Engineering & Environmental Consultants, Inc. -- CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. APPENDIX B Summary of Laboratory Test Results CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Boring Sample o. No. B-1 S-1 ...................... !···-·· ( 15 ft) S-2 Depth (ft) 0 -2 2 -4 Moisture Content (%) 17.2 SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Percent Fines (-#200 Sieve) (%) 45.6 Liquid Plastic Plasticity Limit Limit Index (%) (%) (%) Unconfined or Triaxial Compression Strength (tsO Strain (%) Lateral Pressure (psi) Type of Dry Failure Density (pcO , .................................................................................................................................................................................................................................................................................................................................. . B-2 S-3 S-4 4 -6 6-8 S-5 8 -I 0 S-6 13-15 S-1 0-2 23.8 46.2 34.0 95.8 2 1.4 65.9 40 17 23 1.9 3.0 0 96.7 69 22 47 Pocket Penetro- meter a (tsO NIA NIA 4.5+ NIA 4.5+ 4.5+ IA Comments ................................. __ ... _ ....................... ................. .. .... _ .......... _ ....... _....................... . ( 15 ft) S-2 2 -4 ............................. , .................................................................................................. _ ...................... ........................................... ............................. ............................... . ................... -.............................................. -... S-3 4 -6 2 1.1 59.1 52 19 33 1.9 5.3 t····································i·······················································································································································································································································-·························································-·-····-······ S-4 6 -8 S-5 8-10 34.5 89.5 78 23 55 ....................................................................................................... S-6 13 -15 B-3 S-1 0-2 9.9 52.1 ............................................................... -.. ·--·· .. ·-·-·········-....... ······-·······-····-··-.. -· ( 15 ft) S-2 2 -4 10.1 .............. ___ ........... . S-3 4 -6 16.8 50.0 32 16 16 ................................................................................................................................................................. S-4 6-8 S-5 8-10 S-6 13 -15 See otes at End of Table. B-1 0 Bulge 102.6 1.0 3.0 4.5+ NIA NIA NIA NIA NIA 4.5+ ................... _ ........................................... .. 4.5+ NIA I CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Boring Sample No. o. 8-4 S-1 Depth (ft) 0 -2 Moisture Content (%) 10.3 Percent Fines (-#200 Sieve) (%) 54.8 Liquid Limit (%) Plastic Limit (%) Plasticity Index (%) Unconfined or Triaxial Compression Strength Strain (tsO (%) J_l ~--~L S-2 ..................... ?. ... :::: ... ~............. ---............................................ --................................... ................................................... -. --···········--- S-3 4 -6 I 1.4 50.3 28 15 13 .......................................... ··························-··-········· ···············-·····--·······-·····---··-·-· ............................................................. -..... -··--·--·····-···· Lateral Pressure <osn S-4 6 - 8 27.8 79.1 56 20 36 3.1 3.0 0 S-5 8 -I 0 ......................................................................................................................................................................................................................... , S-6 13 -15 8-5 S-1 0 -2 I 0. I 48.0 46 18 28 .................................................................................... . .................................................................................................................................................................................................................. .. (15 ~) S-2 2 -4 12.5 ...................................................................................... _ --------.. ·--·-·- S-3 4 -6 25.7 71.5 60 21 39 ........................................................... ·•···•••······••···•······. ············-............ ···········--··-·----···-................................................................................... -................................ -.. . ··············-·-··---·· S-4 6-8 Type of Failure Shear Dry Density (ocO 90.2 ··········--- Pocket Penetro- meter • (tsO NIA NIA NIA 4.5+ 4.5+ 4.5+ NIA NIA IA 0.5 S-5 8 -10 31.6 68.3 54 19 35 4.5+ ................................. ·································--........................... ,_,,,,,_ .................. _ .. ,,,____ ···-··-···--·--··-·······--........................................ ······- S-6 13 -15 4.5+ 8 -6 S-1 0-2 16.3 59.5 60 20 40 NIA .................................. ··-....................................................................................................................... ·-·--· ..................................................................................................................................................... ·····--···-........................................... ·······················································-·····--·· (15ft) S-2 2-4 6.9 IA Comments ................................................................................................................................................................... S-3 4-6 26.4 67.8 68 22 46 1.9 5.3 0 ···-~-~-1-~~--94.8 3.0 .................... - S-4 6 - 8 4.5+ .... . ·······-·---------··-·-· ···--·······-·········---···-·······--·-··--···--····-·-----·· ······-···-······--··-· .. --.......... . S-5 8 -I 0 30.1 64.9 47 18 29 4.5+ S-6 13 -15 4.5+ See Notes at End of Table. B-2 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Boring Sample No. No. Depth (ft) Moisture Content (%) B-7 S-1 0 -2 11.8 ....................................................................... ,,,_ SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Percent Fines (-#200 Sieve) (%) 48.0 Unconfined or Triaxial Liquid Plastic Plasticity Compression Limit Limit Index Strength Strain (%) (%) (%) (tsf) (%) 33 16 17 Lateral Type of Dry Pressure Failure Density (psi) (pct) Pocket Penetro- meter a (tsf) NIA (15ft) S-2 2 -4 14.6 NIA ...................................................................... ·················-·· ..................... ·············-............................................................................................. ·······-··-······· .... ····································-··-·I--·· ................................................................................................................................................................................................................................... . S-3 4 - 6 14.6 50.4 26 15 11 3.0 ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ S-4 6-8 ..................... ............................ ················································-··---·····-.............. ·--·-·--···•······- S-5 8-10 32.0 86.4 67 21 46 S-6 13 -15 B-8 S-1 0 -2 I 0. I ...................................................................................... -............ . .................... -........................................................................ .. ( 15 ft) S-2 2 -4 6.2 ................................. . ............................................................ ·-··········-.. - S-3 4 -6 33.1 94.4 B-9 ( 15 ft) S-4 S-5 S-6 S-1 S-2 6-8 8-10 13 -15 0 -2 2 -4 S-3 4 -6 .................................................. ·--·--.. ---··-· S-4 6 -8 27.6 31.4 33.3 ............................................................ ·····-·····-··-·········-···- S-5 S-6 8-10 13 -15 See otes at End of Table. 72 .2 83.3 94.2 71 22 54 20 82 24 49 34 58 .................... ___ ··-·· ·······-·· .. ·-·---·-·-··-·--- 59 20 39 ........................... -......... ·--··-·-··-··· -· ··----··-····-·····-· B-3 NIA 4.5+ 3.0 NIA IA 4.5+ 4.5+ NIA 4.5+ 3.0 2.5 4.5+ 4.5+ 4.5+ 4.5+ Comments I CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Boring Sample No. No. Depth (ft) B-10 S-1 0 -2 ( 15 ft) S-2 2 -4 ...................................................................... ·····················-··- S-3 4 -6 Moisture Content (%) 4.3 Percent Fines (-#200 Sieve) (%) ....................................................................................................................................................... - 8-4 6 -8 29.9 S-5 8 -I 0 .............................................. -·······································-·-··-···- S-6 13 -15 B-1 1 S-1 0 -2 13.4 55.9 (6 ft) S-2 2 -4 Liquid Limit (%) Plastic Plasticity Limit Index (%) (%) Unconfined or Triaxial Compression Strength (tsf) 3.9 .............................................................. -.... , .. ,_,,,, .................................................................................................................................................................................................................................................................. .. S-3 4-6 17.7 7.5 B-1 2 S-1 0 -2 I 0.4 31.8 (6 ft) S-2 2 -4 ........................................................................................................................................................... """""""-""" S-3 4 -6 14.9 50.1 Strain (%) Lateral Pressure (psi) 3.9 0 2.7 0 Type of Failure Shear Dry Density (ocO 89.2 Shear 11 9.3 Pocket Penetro- meter • (tsO 4.5+ NIA 4.0 4.5+ 4.5+ 4.5+ NIA NIA 4.5+ NIA NIA NIA Comments ............................... ---.. ·--·-··-···· .. ·-----· .. ········-···-·-·····-··- B-1 3 S-1 0 -2 15.4 53.8 ................................. ................. .. ............ -.............................................................. .. (6ft) S-2 2 -4 10.8 53.1 34 ...................................................................................................................................................................................................................................... S-3 4 -6 See otes at End of Table. 17 17 B-4 NIA NIA 3.0 I CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC . SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Boring Sample No. No. Depth (ft) 8-14 S-1 0 -2 Moisture Content (%) Percent Fines (-#200 Sieve) (%) Liquid Plastic Limit Limit (%) (%) Plasticity Index (%) Unconfined or Triaxial Compression Strength (tsO Strain (%) Lateral Pressure (psi) Type of Dry Failure Den-sity (pcO Pocket Penetro- meter a (tsO NIA ................................................... (6ft) S-2 2 -4 16.4 55.6 42 18 24 1.8 2.5 0 Shear 100 3.0 S-3 4 -6 1.5 8-15 S-1 0 -2 17.7 46.5 24 15 9 2.0 ................ ························· -···-----······-·-····-· ······-·········-·-·--······ .... ············----..•.......... ···-···-·•··-------·················-···-·-·---····-· --- ( 6 ft) S-2 2 -4 NIA ....................................................................................................................................................................................................................................................................... S-3 4 -6 30.2 71.2 60 20 40 1.7 4.3 0 Shear 88.5 4.5+ 8 -16 S-1 0-2 14.3 53.4 37 17 20 2.3 3.0 0 Shear 106.2 NIA Comments ................................. ·············-····----·-·-·-· .... ····-·····-··--·-······· ....................................... ·······-···---··-··-······ ... .. .................................. -·-······· .. (6 ft) S-2 2.0 2-4 4-6 .............................. -............................................ ,_ .................. _ .. _ . .,. ....... -···-·--········ ................................................... -.......... . S-3 17.7 58.6 32 16 16 8 -17 -I 0 -2 12.7 54.4 (6ft) S-2 2-4 ............................................................................................................................................................................................................................................................................................................................................................................................. ···········-·-···· ......... ··············--·······--····- S-3 4 -6 17.0 62.4 58 21 37 2.0 3.8 0 8-1 8 S-1 0 -2 9.2 47.7 ................................................................................................................................................ ·-..................................... ---.................................. .. J?ft.) ............. ?..:.? ..................... .2.. -:: .. ~ .... .. ... . . .. .. . . . ......... --............................................. --. .. ...... .. .. ..... ---.. - S-3 4 -6 20.4 65.4 1.9 2.7 0 See Notes at End of Table. B-5 Shear 99.7 Shear I 00.1 3.0 NIA NIA 4.0 IA NIA 3.0 I CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Boring Sample No. No. Depth (ft) B-19 S-1 0-2 (6 ft) S-2 2 -4 Moisture Content (%) 6.1 SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Percent Fines (-#200 Sieve) (%) 2 1.6 Liquid Plastic Plasticity Limit Limit Index (%) (%) (%) Unconfined or Triaxial Compression Strength Strain (tsf) (%) Lateral Pressure (psi) Type of Failure Dry Density (pcf) ............................................ --.··--·-·-····················--···-···································································-···· Pocket Penetro- meter • (tsf) NIA NIA Comments , ................................. , ...................................... , ............................................. , ............................................................................................................................................................................................................................................................................................................... -........... -............. .. ..... .................. . . .............................................................................................................. . S-3 4 -6 15.3 51.3 3 1 16 15 NIA ·········--·--··----···-···· ·······------····--············--·· ···--------·-·····-... --------···-·· ··-··-····-···-·--···-·-·-· .. --·-·----··-.. ·-........................ ···-·-···---·-·····-·····--·····--·--··-··- B-20 S-1 0 -2 14.5 46.6 ......... ·····················································-...... ·····················--··········································--.................................. .. (6ft) S-2 2 -4 , .................................. , ...................................... , .............................................. , ................................................................................................................................................................................................................................................................................................. . S-3 4 -6 21.4 48.1 52 20 32 2.3 4.1 B-21 S-1 0-2 13.6 62.9 40 17 23 (6ft) S-2 2-4 , .................................. , ....................................... , .............................................. , .................................................................................................................................................................................................... -....... . S-3 4 -6 10.6 55.5 43 18 25 B-22 S-1 0 -2 9.9 54.3 30 16 14 ( t) S-2 2 -4 , .................................. , .............. . S-3 4 -6 17.6 66.0 45 18 27 2.2 4.2 B-23 S-1 0 -2 14.3 52.4 .......................................................................................................................... (§f.t.2 .............. ?.:?...... ?.::-4 S-3 4-6 15.2 57.6 See Notes at End of Table. B-6 0 Shear 103.7 0 Shear 107.4 NIA ····················-· ···-····· ·····························-·· ...... NIA 2.5 NIA 4.5+ 4.5+ NIA 3.0 3.5 IA NIA NIA • CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Boring Sample No. No. B-24 S-1 ··········································-··· (15 ft) S-2 S-3 Depth (ft) Moisture Content (%) 0 -2 11.6 2 -4 4 -6 24.6 SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Percent Fines (-#200 Sieve) (%) 45.3 65.6 Unconfined or Triaxial Liquid Plastic Plasticity Compression Lateral Type of Limit Limit Index Strength Strain Pressure Failure (%) (%) (%) (tsO (%) (psi) 59 21 38 2.1 3.4 0 Shear B-2 s. ............. ?..: . .'.. o -2 ............ , ................. 2 ..... 3 ...... ·. o ................................... 5 .... 6 ...... · .. 1 .................. , ................ 3 ..... 9 ................. . 17 22 ( 15 ft) S-2 2 -4 ···············································································································-· S-3 4 -6 ................................................................................................ S-4 6-8 S-5 S-6 8-10 13 -15 B-26 S-1 0-2 ..... ··············································-··-·· .. ·-·-· .... ·-·- (15 ft) S-2 2-4 22.3 62.3 48 19 29 12.8 51.6 28 15 13 ········--·--·--·----· ...... _ --·····-····---·--·-···-···-·---··-··········-············-··················---·-······--·····----·-·-··-··-···-·········---·-·------·-----·-·--·----·---·------ S-3 4 -6 32.0 1.8 5.0 0 ............................................................................. _ .. , ........ -.. -.................... _. ________________ .. _., ___ ............................................................ -.................................................................................................................. .. S-4 6-8 S-5 8-10 S-6 13-15 See otes at End of Table. B-7 Shear Dry Density (pcO 92.3 Pocket Penetro- meter • (tsf) IA NIA 4.5+ IA NIA 2.5 4.5 4.5+ 4.5+ NIA NIA Comments ...... -.................... --·---·---·-·--·-----·--.............................. --············-·-·········· 86.1 3.0 4.5+ 4.5+ 4.5+ • CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. SUMMARY OF LABORATORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Boring No. ample No. B-27 S-1 Depth (ft) 0 -2 .................................. ··-···-·····-··-............. ·········-······-··--···--·-··- (I 5 ft) S-2 2 -4 S-3 4 -6 S-4 6 -8 .................... ·········-··---·-···········--·······-··· S-5 8 -I 0 S-6 13 -15 Moisture Content (%) 16.8 31.4 Percent Fines (-#200 Sieve) (%) 32.8 51.4 B-2 8 S-1 0 -2 16.6 50. I Liquid Plastic Plasticity Limit Limit Index (%) (%) (%) 24 15 9 48 18 30 Unconfined or Triaxial Compression Strength (tsf) Strain (%) Lateral Pressure (psi) ···························-·········-·-................................................. ······-·····----···········-·····--··-·-·····························-·· -·······················-!--······-·-··········-··-··-··-····--··--·· ·--·-···--··-·-·····-··· ······-····--·-···-······ (!?ftL __ ?~~ ............ 3-~-~ 2?.:?. __ ._ ·--··7-6.4 65 21 --~~------·-----------··--· S-3 4 -6 ......................... .... ... ....•... .. .... . ............ ·······-···-·-·-··--····---···-· ···•·•·········•··············••· ·························---·---· ·•···•········•····•··•·•···•····· ·······················-············--····· ····················-·······-····-·--·---·-.................... ·····-···· ................................... .. S-4 6 - 8 31.3 80.6 51 19 32 S-5 8 -I 0 .................................................................................. B-29 ( 15 ft) S-6 13 -15 S-1 S-2 S-3 0-2 2 -4 4 -6 30.0 83.4 19.3 55.4 57 20 37 Type of Failure ·--·-·-·-·· -· ......... ·-·-·····--··----··-·-·-·-····-·-················----·---···-··-···-····-------··-·· ······-----······-··-···· S-4 S-5 S-6 6-8 8-10 13 -15 See Notes at End of Table. 30.1 54.5 54 19 35 B-8 Dry Density (pct) Pocket Penetro- meter • (tsf) NIA NIA NIA 3.5 4.5+ 4.5+ 4.5+ 4.5+ 3.5 4.0 4.5+ 4.5+ NIA 2.0 3.0 4.5+ 4.5+ 4.5+ Comments I CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS , INC . SUMMARY OF LABO RA TORY TEST RESULTS The Barracks Subdivision -College Station (Brazos County), Texas Percent Unconfined or Fines Triaxial Pocket Boring Sample Moisture (-#200 Liquid Plastic Plasticity Compression Lateral Type of Dry Penetro- No. No. Depth Content Sieve) Limit Limit Index Strength Strain Pressure Failure Density meter• Comments (ft) (%) (%) (%) (%) (%) (tsO (%) (psi) (ocO (tsO B-30 S-1 0 -2 16.4 55 .2 NIA ( 15 ft) S-2 2 - 4 NIA ··········································--··· .. ·-.................................................................................. ···············--··········•·················-·-·---··-····----·-··-····-......................................................................................................................................................................................................................................................................................................... . S-3 4 -6 23.7 60.1 1.8 5.3 0 Bulge 97.0 3.5 ·································· ..................................... ···········-···-·-· ............... ····-···-....... -........... ,_ .... -..... ··--.. ·---·-···-.. ·-.. ····--............................... ____ ,, .................. -----·-···-·-.......... ··········-·-···-···-······---·-.. ···-·-.............. ,_, __ ,_., ...................................................................... ,_ ·······----··-------- S-4 6 -8 4.5+ S-5 8 -I 0 ....................................................................................................................................... ........... ················-·······--···+-·······-····-·-·--···-······+······················-················+·-··-.. ·-······-4·--. 5._+·-·········-·········+······························ .. -... ·-.. --·· .. ···-·-.. ·····-·-··-··· S-6 13 -15 4.5+ ............................ _ ·········--r---·- 8-3 I -I 0 -2 I I. 7 54.3 .............................................................................................................................................................................................................................................................................................................................................................................................................................. -...... NIA NIA (15 ft) S-2 2-4 14.7 60.9 ......................... , ... _ ................. ............................................ ....... .. .................................. .. .. ................................... ,_, __ ............ ·-··-·-······-.......... ·---···· ______ ......................................................... .. S-3 4-6 NIA S-4 6 -8 4.0 ....................................................................................................... .......... --r-· S-5 8 -I 0 32.7 80.5 62 21 41 4.0 S-6 13 -15 4.5+ Notes: a. PP = Pocket penetrometer reading which represents estimates of unconfined compression tests in tons per square foot (tst). b. N-P means Non-Pl astic, i.e., the Liquid Limit -Plastic Limit = Pl asticity Index of -0. B-9