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Home My WebLink About20210922160055312_Page_01June 27, 2011 Mr. Kent M. Laza, P.E., Manager Phillips Engineering 4490 Castlegate Drive College Station, TX 77845 Re: Report of Subsurface Exploration and Geotechnical Study for Proposed Deacon Drive Extension in the Barracks II Subdivision From Old Wellborn Road to Holleman Drive South College Station, Texas CSC Project Number 11063-34 Dear Mr. Laza: CSC Engineering & Environmental Consultants, Inc. (CSC) is pleased to submit to Phillips Engineering (PE), two (2) copies (one (1) original unbound document and one (1) bound photocopy) of the accompanying report describing the subsurface exploration and geotechnical study performed by CSC along the alignment of the proposed Deacon Drive Extension in College Station, Texas. The work associated with the subsurface exploration and geotechnical study associated with this project was performed in accordance with CSC's proposal to PE dated May 24, 2011. The proposal was accepted by Mr. Heath Phillips Mr. Heath Phillips on behalf of Heath Phillips Investments, LLC, the developer of the subdivision, on May 26, 2011. General Project Description. The proposed Deacon Drive Extension will extend west for a distance of approximately 3,600 feet from the railroad crossing at Old Wellborn Road to Holleman Drive South. The proposed roadway will extend through improved pastureland and will cross existing ephemeral drainage ways that are situated near the western and central portions of the proposed Barracks II Subdivision. The roadway will be constructed within an 85 foot wide right-of-way (ROW). The paved roadway cross- section will be approximately 48 feet wide as measured from back-to-back of curb. The paved roadway section will include two (2) drive -through or travel lanes, one turning lane, as well as bike lanes. Sidewalks will be constructed on both sides of the roadway. The final grading plans associated with the proposed roadway extension are not known at the present time, but some preliminary site grading concepts have been formulated. We believe that approximately 4 to 5 feet of fill will be needed over limited segments of the proposed roadway alignment to cross the existing drainage ways in order to elevate the roadway grades at the crossing locations. We anticipate that most of the remaining length of the roadway will only require less than 2 to 3 feet of excavation or fill placement in order to achieve final grades. A zone change Traffic Impact Analysis (TIA) was conducted to ascertain the specific conditions as traffic is routed through the proposed Barracks II Subdivision development. The specific traffic loads developed 3407 Tabor Road Phone (979) 778-2810 Bryan, Texas 77808 Fax (979) 778-0820 Mr. Kent M. Laza, P.E., Manager, Phillips Engineering Transmittal of Report of Subsurface Investigation and Geotechnical Study for Proposed Deacon Drive Extension in the Barracks II Subdivision From Old Wellborn Road to Holleman Drive South; College Station, TX Page 2 in the TIA included traffic volumes and patterns that are anticipated through the "fill build -out' of the subdivision through 2015. We also understand that the average daily (two-way) traffic count (ADT) for the proposed roadway over its design life period was determined by the TIA. However, subsequent to the completion of the TIA, the anticipated ADT was modified slightly based on anticipated land use and is documented in a letter prepared by Mr. Kent Laza, P.E. or Phillips Engineering and entitled "Anticipated Traffic Generation Rates, The Barracks II Subdivision, College Station, Texas, April 1, 2011. We believe that the traffic utilizing the proposed roadway will predominantly consist of light passenger vehicles with a small percentage of heavy buck traffic. Field Exploration and Laboratory Testing Study. The field exploration program was initiated and completed on June 6, 2011. The field exploration program, along the proposed roadway alignment consisted of drilling eight (8) borings that were advanced to depths varying from approximately 6 feet below the existing surface grade along the major portion of the roadway route where minimum cuts or fills were anticipated, to 10 feet below the existing surface grade at the planned drainage way crossing. Three (3) additional borings were also drilled in areas of proposed storm water detention basin of the planned development. Geotechnical laboratory classification and strength tests were assigned to selected soil samples recovered during the field exploration program. The laboratory testing for the project was completed on June 11, 2011. The transmitted report documents the results of the field exploration and the related laboratory testing programs. Subsurface Stratigraphy. The subsurface stratigraphy was somewhat variable along the approximately 3,600 feet length of the roadway as might be expected. The subsurface shatigraphy can generally be divided into two (2) distinct zones: (1) a surficial zone that extended to depths ranging from 0.3 to 3 feet at the various boring locations and which contained granular soils that consisted of silty sands that typically exhibited a loose relative density; and (2) a near -surface or intermediate zone composed of strong soils that ranged from clayey sands to sandy clays to clays of moderate to high plasticity and which extended from immediately below the bottom of the surficial zone to the maximum exploration depths ranging from 6 to 10 feet below the surface at the various boring locations. All of the borings were advanced using dry auger drilling techniques so that ground water levels could be monitored during and immediately following completion of drilling. No ground water was observed in any of the eight (8) roadway boreholes dining drilling or immediately following completion of the drilling operations. Report Recommendations. The report contains recommendation for both rigid and flexible pavement sections that are being considered for the proposed roadway. The recommended pavement sections were determined from the previously stated assumed traffic characterization and the anticipated natural and embankment soil subgrade conditions. The rigid pavement section is composed of a Portland cement concrete (PCC) surface course and a chemically stabilized and compacted subgrade soil layer. The flexible pavement section has a hot mix asphalt concrete (HMAC) surface course, a crushed rock base course that is also known as flex -base, and a chemically stabilized and compacted subgrade soil layer. The transmitted report presents recommendations related to construction of the proposed project including embankment fill placement and preparation of the embankment subgrade soils, stabilization of the pavement subgrade soil layer, and material characteristics and placement requirements for roadway project materials. 080 ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Mr. Kew M. Laza, P.E., Manager, Phillips Engineering Transmittal of Report of Subsurface Investigation and Geotechnical Study for Proposed Deacon Drive Extension in the Barracks II Subdivision From Old 'WellboniRoad to Holleman Drive South; College Station, TX 'age 3 Closing. CSC would like to thank you for the opportunity to be of service to Heath Phillips Investments, LLC, Phillips Engineering, and the City rof College: Station on thus project and looks forward to continuing our working relationship in the 'future. If you have any questions or need any additional -- information, please do not hesitate to contact me at (979.) 778-2810. Kindestregards, M. Frederick Conlin, Jr., P,E, Senior Engineer MFCrc Enclosures Via e-mail[klaza@pbillipsengineeringbes,coin] and Hand Delivery C86 ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. REPORT OF SUBSURFACE EXPLORATION AND GEOTECHNICAL STUDY PROPOSEDDEACON DRIVE EXTENSION FROM OLD WELLBORN ROAD TO HOLLEMAN DRIVE SOUTH COLLEGE STATION, TEXAS Preparedor Phillips Engineering 4490 Castlegate Drive College Station, TX 77845 Prepared by CSC Engineering & Environmental Consultants, Inc. 3407 Tabor Road Bryan, Texas 77808 Texas Board of Professional Engineers Firm Registration Number: F-1078 CSC Project Number; 11063 Rptl. tl °••"•'. June 27,2011 M F CGN411M,JR. 44161 kt� M. Frederick Conlin, Jr., P.E. Senior Engineer W. R. Cullen, P.E. QA/QC Reviewer - Senior Engineer CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX TABLE OF CONTENTS Page 1.0 INTRODUCTION.......................................................................................................................... I 1.1 PROJECT DESCRIPTION................................................................................................... 1 1.1.1 Sources of Project Information................................................................................. 1 1.1.2 General Description of Proposed Project................................................................. 1 1.1.3 Proposed Project Grading Plans Along the Roadway Extension ............................. 2 1.1.4 Traffic Characterization........................................................................................... 3 1.1.5 Pavement Sections.................................................................................................... 3 1.1.6 Utilities Associated With Proposed Roadway Project ............................................. 4 1.2 OBJECTIVES OF THE EXPLORATION AND STUDY .................................................... 4 1.3 LIMITATIONS OF SCOPE OF STUDY............................................................................. 5 1.4 REPORT FORMAT.............................................................................................................. 5 2.0 FIELD EXPLORATION PROGRAM............................................................................................ 7 2.1 BORING LOCATIONS AND DEPTHS.............................................................................. 7 2.2 DRILLING AND SAMPLING TECHNIQUES................................................................... 7 2.3 OBSERVATION OF GROUND WATER LEVELS IN BOREHOLES .............................. 8 2.4 BORING LOGS.................................................................................................................... 8 2.5 SAMPLE CUSTODY........................................................................................................... 9 3.0 LABORATORY TESTING PROGRAM....................................................................................... 10 3.1 CLASSIFICATION TESTS AND MOISTURE CONTENT TESTS .................................. 10 3.2 STRENGTH TESTS............................................................................................................. 10 4.0 SITE OBSERVATIONS OF SURFACE CONDITIONS ALONG ALIGNMENT OF ROADWAY AND DESCRIPTIONS OF SUBSURFACE STRATIGRAPHY ............................. 12 4.1 DESCRIPTION OF SURFACE CONDITIONS ALONG ALIGNMENT OF ROADWAY.......................................................................................................................... 12 4.2 DESCRIPTION OF SUBSURFACE OR STRATIGRAPHICAL CONDITIONS ............... 12 4.2.1 Soil Classification System Used in Subsurface Descriptions ................................... 12 4.2.2 General Description of Subsurface Stratigraphy...................................................... 14 4.2.3 Limitations of General Description of Subsurface Stratigraphy .............................. 15 4.2.4 Water Level Observations........................................................................................ 15 5.0 GENERAL PAVEMENT SYSTEM RECOMMENDATIONS..................................................... 18 5.1 GENERAL ANALYTICAL PROCEDURES FOR DESIGN OF PAVEMENT SECTION FOR PROPOSED ROADWAY.......................................................................... 18 5.2 SUBGRADE CLASSIFICATION........................................................................................ 18 5.2.1 General Discussion of Anticipated Pavement Subgrade Soils ................................. 18 5.2.2 Potential Problem Areas Of Existing Soils Within the Planned Subgrade Zone of the Pavement and Embankment.................................................................. 19 5.2.3 Chemical Stabilization of Roadway Pavement Subgrade Soils ............................... 20 5.3 PROJECTED TRAFFIC VOLUMES AND CHARACTERISTICS .................................... 21 5.4 PAVEMENT SECTION THICKNESS REQUIREMENTS ................................................. 22 5.5 PAVEMENT SYSTEM DRAINAGE AND MAINTENANCE ........................................... 24 5.5.1 Pavement Drainage................................................................................................... 24 5.5.2 Pavement Maintenance............................................................................................. 24 6.0 SITE DEVELOPMENT AND CONSTRUCTION CONSIDERATIONS ..................................... 25 6.1 CLEARING OF EXISTING SURFACE VEGETATION AND STRIPPING OF SURFICIAL ORGANIC MATERIALS............................................................................... 25 ii CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 6.2 PROOF ROLLING OF ROADWAY EMBANKMENT SUBGRADE SOILS .................... 25 6.3 COMPACTION OF SUBGRADE SOILS IN PAVEMENT AREAS .................................. 26 6.4 SITE GRADING AND DRAINAGE.................................................................................... 26 6.5 SELECT ROADWAY EMBANKMENT FILL SOILS MATERIAL CHARACTERISTICS AND PLACEMENT PROCEDURES ............................................. 27 6.5.1 General..................................................................................................................... 27 6.6 PAVEMENT SUBGRADE STABILIZATION REQUIREMENTS .................................... 28 6.7 FLEXIBLE AND RIGID PAVEMENT SECTION MATERIALS REQUIREMENTS ...... 29 6.7.1 Flexible Pavement Base Course and Surface Course ............................................... 29 6.7.2 PCC Pavement, Curb and Gutter, and Drainage Structures ..................................... 29 7.0 BASIS OF RECOMMENDATIONS.............................................................................................. 31 LIST OF TABLES Page Table 1. Additional Pavement Design Values For Proposed Deacon Drive Extension ...................... 4 Table 2. Pavement Thickness Schedule for Conventionally Reinforced and Jointed PCC................. 22 Table 3. Pavement Thickness Schedule for Hot -Mix Asphalt Concrete (HMAC) ............................. 23 LIST OF APPENDICES Appendix A — Figures, Boring Logs, and Key Sheets to Terms and Symbols Used on the Boring Logs Figures Figure I — Project Vicinity Map Figure 2 — Site Plan and Plan of Borings Boring Logs B-1 through 13-11 (borings B-1 through B-8 are for roadway and borings B-9 through B-1 I are for ponds) Key Sheet to Terms and Symbols Used on the Boring Logs Appendix B— Summary of Laboratory Test Results iii CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 1.0 INTRODUCTION This report was prepared by CSC Engineering & Environmental Consultants, Inc. (CSC) and documents the results of the subsurface exploration and geotechnical study of geologic conditions along the planned route of the proposed Deacon Drive Extension. The proposed project will involve the construction of a new roadway as part of development of the Barracks II Subdivision as illustrated on Figure 1 — Project Vicinity Map in Appendix A of this report. The area of the proposed roadway extension project is hereinafter referred to as the project site. The work associated with the subsurface exploration and geotechnical study associated with this project was performed in accordance with CSC's proposal to PE dated May 24, 2011. The proposal was accepted by Mr. Heath Phillips on behalf of Heath Phillips Investments, LLC, the developer of the subdivision, on May 26, 2011. 1.1 PROJECT DESCRIPTION 1.1.1 Sources of Project Information Information concerning the project was initially provided in telephone conversations with Mr. Kent Laza, P.E. on April 19, 2011 and May 12, 2011. Additional layout and design information relative to the proposed alignment was provided in e-mail correspondence on April 20, 2011 which also included the "concept plan" for the proposed Barracks II Subdivision development. Further information concerning preliminary grading plans and utilities along the roadway were outlined in an e-mail communication from Mr. Laza on April 28, 2011. Finally, information concerning anticipated traffic volumes was determined from a traffic study performed by Brown & Gay Engineers, Inc. (BGE) and entitled Zoning Traffic Impact Analysis — The Barracks Development and dated August 2010. 1.1.2 General Description of Proposed Project The proposed Deacon Drive Extension will extend west for a distance of approximately 3,600 feet from the railroad crossing at Old Wellborn Road to Holleman Drive South as illustrated on Figure 2— Site Plan and Plan of Borings in Appendix A. The proposed roadway will extend through improved pastureland and will cross existing ephemeral drainage ways that are situated near the western and central portions of the Barracks II Subdivision. The proposed Deacon Drive Extension is listed as a minor collector in the City of College Station Thoroughfare Plan. However, we understand that the proposed extension will essentially be constructed CSC ENGINEERING . & ENVIRONMENTAL CONSULTANTS, I N C . Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX as a major collector. A major collector is defined under the Bryan/College Station Unified Design Guidelines for Streets and Alleys, which is hereinafter referred to as the Guideline. Table VI — Street Classification Definitions of the referenced Guidelines defines a major collector street as... A street which primarily serves vehicular traffic (in the general range of 5, 000 to 10,000 VP [vehicles per dao] fi•otn residential streets and minor collectors to arterials. A collector may also provide very limited access to abuttingproperties is approved by the City. As part of the development requirements, the previously referenced zone change Traffic hnpact Analysis (TIA) was conducted to ascertain the specific conditions as traffic is routed through the proposed Barracks II Subdivision development. The specific traffic loads developed in the TIA included traffic volumes and patterns that are anticipated through the "full build -out" of the subdivision through 2015. We also understand that the average daily (two-way) traffic count (ADT) for the proposed roadway over its design life period was determined to be approximately 6,780 vehicles per day for the proposed roadway, which lies within the previously cited range of vehicles per day for a major collector street. However, subsequent to the completion of the TIA, the anticipated ADT was modified slightly to approximately 6,075 vehicles per day. This revised ADT was computed on specific design information relative to anticipated land use and is documented in a letter prepared by Mr. Kent Laza, P.E. and entitled "Anticipated Traffic Generation Rates, The Barracks II Subdivision, College Station, Texas, April 1, 201 L" We anticipate that the roadway will be constructed within an 85 foot wide right-of-way (ROW). We anticipate that the paved roadway cross-section, as determined by the TIA, will be approximately 48 feet wide as measured from back-to-back of curb. The paved roadway section will include two (2) drive - through or travel lanes, one turning lane, as well as bike lanes. Sidewalks will be constructed on both sides of the roadway. 1.1.3 Proposed Project Grading Plans Along the Roadway Extension The final grading plans associated with the proposed roadway extension are not known at the present time, but some preliminary site grading concepts have been formulated. The existing topography along the route of the proposed roadway is very flat and the roadway design will have to create a positive slope along the roadway alignment to effectively drain the We believe that approximately 4 to 5 feet of fill will be needed for very limited lengths of the proposed roadway alignment in order to elevate the roadway grades at the proposed drainage way crossing locations. However, we anticipate that most of the remaining length of the roadway will only require less than 2 to 3 feet of excavation or fill placement in order to achieve final grades. 2 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 1.1.4 Traffic Characterization Information for traffic volumes and patterns were developed in the previously referenced TIA and supplemental letter prepared by Mr. Kent Laza, P.E. Consequently, we have assumed an average daily traffic count (ADT) of 6,075 vehicles per day for design of the proposed roadway pavement sections. The traffic volume is believed to be representative for the average daily traffic volume for a "full build -out' condition and incorporates specific growth factors for the area. In addition, we have assumed that a small percentage of the traffic on the proposed roadway will of medium- to heavy -weight trucks. We believe that the percentage of heavy -weight trucks that will be part of the daily vehicle count for the proposed roadways will be in the order of 2 percent of the ADT. We believe that the percentage of trucks using the proposed roadway will be limited by the restricted connectivity of the proposed roadway with any connecting streets to the south of Holleman Drive South. Heavy weight trucks are described as those with two (2) or more axles and six (6) or more tires. Most of the heavy -weight trucks that will utilize the proposed roadways are expected to be no larger than typical solid waste collection trucks, i.e., trucks having a single front axle and a tandem rear axle group. The maximum loading of the front axle is expected to be 20,000 pounds and the maximum loading of the tandem rear axle is expected to be 34,000 pounds that would result in a gross vehicle weight (GVW) of approximately 54,000 pounds. Only a few very heavy -weight bucks, such as large tractor -trailer combinations, are expected to utilize the roadway. The very heavy -weight trucks would have a single front axle, and a middle and rear tandem axle with similar axle loads as previously described for the heavy -weight trucks that would result in GV Ws in the range of 72,000 to 80,000 pounds. Other pavement design values are presented in the following Table I — Other Pavement Design Values. The referenced traffic information was utilized to develop projections of anticipated traffic volumes, patterns, and vehicle characteristics that could be expected for the proposed roadway extension. 1.1.5 Pavement Sections As previously discussed, we believe that both rigid pavement and flexible pavement sections are being considered for construction of the proposed roadway. The rigid pavement section will consist of a surface course of Portland cement concrete (PCC) constructed over a chemically stabilized and compacted subgrade soil layer. The flexible pavement section is expected to consist of a surface course of hot mix asphalt concrete (HMAC), a base course of crushed limestone rock referred to as flex -base, and a chemically stabilized and compacted subgrade soil layer. IF CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX Table I. Additional Pavement Design Values For Proposed Deacon Drive Extension PAVEMENT RIGID' PAVEMENT.. FLEXIBLE DESIGN PARAMETER SECTION PAVEMENT SECTION Reliability 90 percent 90 percent Standard Deviation 0.35 0.45 28-dayFlexural Strength 650 psi -- Load Transfer, J 2.7 Drainage Coefficient 0.9 -- Initial Serviceability Index 4.5 4.2 Terminal Serviceability Index 2.25 2.25 1.1.6 Utilities Associated With Proposed Roadway Project We anticipate that there will be three (3) standard public utility lines along the proposed roadway alignment. The three (3) lines will consists of a domestic water line, a sanitary sewer line, and storm sewer or drainage lines. While the designs of the proposed utilities have not been completed, we anticipate that the domestic water line will have a diameter of approximately 12 inches and a burial depth in the order of 5 to 6 feet. The sanitary sewer line will likely be 12 to 18 inches in diameter with a burial depth expected to be in the order of 6 to 8 feet. The storm drain lines are expected to vary in diameter along the length of the roadway and to have burial depths, in the order of 4 to 6 feet below the existing surface grade. 1.2 OBJECTIVES OF THE EXPLORATION AND STUDY We understand that the current geotechnical study was performed to identify subsurface conditions along the alignment of the proposed roadway. The specific objectives of the subsurface exploration and geotechnical study were to: Secure information on the general surface and subsurface conditions at the boring locations along the length of the proposed roadway. • Evaluate the subsurface soils information developed from the field exploration and laboratory testing program. 4 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX • Perform an engineering analysis of the subsurface information developed from the field exploration and laboratory testing program in order to develop recommendations for pavement design and drainage way crossing structure design associated with the proposed roadway. • Present recommendations for pavement system design and drainage crossing structure design in a written engineering report along with discussions of construction considerations. 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 pavement system and the drainage way crossing of the proposed roadway. 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 [except as their mechanical properties might impact the proposed pavement systems], gasoline, diesel, or other fuels or pollutants in the soil, rock, ground water, or surface waters), historical uses of the site, threatened or endangered species, or the presence of jurisdictional wetlands or "waters of the United States" on the site. These environmental conditions are typically addressed as part of separate biological studies, environmental constraints studies, environmental site assessments (ESAs), or ecological assessments (EAs). 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 project elements. First, descriptions of the field exploration program are presented in Section 2. Appendix A contains the project vicinity map, the project site plan and boring location map (plan of borings) that illustrates where the exploratory borings were drilled. 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 summary discussion of the laboratory tests performed for the project. 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. 5 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX Section 4 of the report offers a description of our observations of surface conditions along the alignment of the proposed roadway at the time of the field study. A general discussion and interpretation of subsurface conditions developed from the field and laboratory studies is also presented in Section 4. Section 5 of this report presents CSC's recommendations for the design and construction of the proposed rigid and flexible pavement systems. Section 6 of the report offers a general discussion of surface and subsurface conditions encountered at the boring locations that might have a significant impact upon site development and construction operations. Section 6 also offers specific guidance with respect to construction material characteristics and placement requirements for the materials expected to be associated with the proposed project. Finally, Section 7 presents the basis for the recommendations given in the report and the general limitations for the information presented as part of the report. 0 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 2.0 FIELD EXPLORATION PROGRAM 2.1 BORING LOCATIONS AND DEPTHS Subsurface conditions along the alignment of the proposed roadway extension were explored by drilling a total of eight (8) sample borings. The boring locations were selected by CSC in consultation with PE. The boring locations are illustrated on the previously referenced Figure 2 in Appendix A of this report. As can be seen from a review of Figure 2, the borings extended along the entire length of the planned roadway alignment with boring B-1 being located near the western end of the proposed roadway alignment near the proposed intersection with Holleman Drive South, and boring B-8 being situated near the planned intersection of the roadway with the existing Old Wellborn Road at the eastern end of the proposed roadway route. In addition, three (3) borings (B-9 through B-I 1) were advanced in the area of proposed detention ponds that will be constructed as pail of the proposed Barracks II Subdivision development. The borings that were advanced along the proposed roadway alignment varied in depth from 6 to 10 feet below the existing ground surface elevation. All of the boring depths are referenced to the ground surface elevation existing at each boring location at the time of the field exploration. Existing ground surface elevations at each of the boring locations are not known at the present time and surface elevations could not therefore be noted on the logs of boring. It should be recognized that subsequent discussions and recommendations presented in this report are referenced to the surface grade existing at the time of the field study. If adjustments to the present surface elevations are made as part of site grading operations prior to construction of the foundation support systems, some adjustment in the subsequent discussions and recommendations with respect to foundation depths may warranted. 2.2 DRILLING AND SAMPLING TECHNIQUES All of the borings were drilled with a buggy -mounted, Failing 36 drill rig using dry auger drilling techniques. The dry auger drilling techniques were used in order to monitor short-term ground water conditions both during and immediately following completion of the drilling activities. Soil samples were obtained from all of the borings continuously to a depth of 6 feet in the shallower borings to 10 feet in the deeper borings. Samples of cohesive soils, i.e., clays, and cohesive -granular soils, i.e., clayey sands, were obtained by mechanically pushing a 3-inch-diameter, thin -wall "Shelby -tube" sampler in general 7 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX accordance with the procedures outlined in ASTM D 1587-00 - Standard Practice for Thin -Walled Tube Sampling of Soils for Geotechnical Proposes. Samples of cohesive —granular soils (i.e., clayey sands) or granular soils (i.e., sands) were generally obtained during the performance of the Standard Penetration Test (SPT). The SPT was performed in general accordance with the procedures outlined in ASTM D 1586 — Standard Test Methods for Penetration Test and Split -Barrel Sampling of Soils. The SPT involves driving a 2-inch diameter split - barrel sampler into the soils. The spilt -barrel or split -spoon sampler is driven into the soil for three successive 6-inch increments with blows from a 140-lb hammer. The vertical travel of the hammer was 30 inches in accordance with ASTM D 1586. 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 (and is represented by the letter 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 100 blows have been applied or if the sampler has not advanced after 10 successive hammer blows. The N-values determined for the SPTs are recorded as part of the performance of the test. The depths at which samples were collected, the types of samples collected, and the results of field tests are presented on the individual boring logs in Appendix A. 2.3 OBSERVATION OF GROUNDWATER LEVELS IN BOREHOLES As previously mentioned, all of the boreholes were drilled using dry auger drilling techniques so that ground water could be observed during and immediately following completion of drilling activities. The results of the ground water observations are presented in a Section 4 of this report. Following completion of drilling and short-term ground water monitoring, the boreholes were filled with soil cuttings to limit moisture infiltration into surface formations and as a safety precaution for pedestrian and animal traffic within the project area. 2.4 BORING LOGS A field geotechnical engineer was present during the field exploration to describe the subsurface stratigraphy and to note obvious anomalies in the stratigraphy that may have been present at specific bor- ing locations. Descriptions of the subsurface conditions encountered at the individual boring locations are shown on the individual boring logs presented in Appendix A of this report. A "Key to Symbols and Soil Classification" sheet explaining the terms and symbols used on the logs is presented immediately following the logs. The logs represent CSC's interpretation of the subsurface conditions based upon the field geotechnical engineer's notes together with engineering observation and classification of the materi- M CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX als in the laboratory. The lines designating the interfaces between various strata represent approximate boundaries only, as transitions between materials may be gradual. 2.5 SAMPLE CUSTODY Representative soil samples recovered during the drilling operations 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. E CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 3.0 LABORATORY TESTING PROGRAM Samples of subsurface materials recovered from the borings were examined and classified by the geotechnical engineer and various laboratory tests were 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 testing study was completed on June 11, 2011. The laboratory test results are presented in a summary tabular form in Appendix B. The results of the laboratory testing programs are also presented symbolically and numerically on the individual boring logs. As previously stated, the symbols and terms used on the logs are explained both on the logs and also on the Key to Symbols and Soil Classification sheet presented immediately following the logs. 3.1 CLASSIFICATION TESTS AND MOISTURE CONTENT TESTS Tests were performed in order to classify the foundation soils in accordance with the Unified Soil Classification System (ASTM D 2487-06 — Standard Test Method for Classification of Soils for Engineering Purposes (Unified Soil Classification System), which is hereinafter referred to as the USCS, and to determine the soil -moisture profile at the boring locations. The classification tests performed consisted of Atterberg limits determinations (liquid limit and plastic limit) and grain -size distribution determinations. The Atterberg limit determinations were performed in general accordance with the procedures outlined in ASTM D 4318-05 — Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. The grain -size distribution tests were also performed to determine the percent of soil particles passing the U.S. Standard sieve size No. 200 (ASTM D 1140-00 — Standard Test Method for Amount of Material in Soils Finer Than No. 200 (75-pm) Sieve). The soil fractions passing the No. 200 sieve size are the silt- and clay -size particles and are generally referred to as "fines," as subsequently discussed in greater detail in Section 4. The natural moisture content of individual samples was determined in accordance with the procedures outlined in ASTM D 2216-05 — Standard Test Methods for Laboratory Determination of' Water (Moisture) Content of Soil and Rock by Mass. 3.2 STRENGTH TESTS 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- 10 CSC E N 13 1 N E E R I N G & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX value of the soils. The unconfined compression test was performed in the laboratory on undisturbed samples of cohesive soils to determine the compressive strength characteristics. The test procedures outlined in ASTM D 2166-06 — Standard Test Method for Unconfined Compressive Strength of Cohesive Soil were utilized. The unit dry weight was also determined for each unconfined compression test sample in accordance with the procedures outlined in ASTM D 2166. In addition, hand or pocket penetrometer tests were also performed both in the field and in the laboratory on 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 site has indicated that the hand penetrometer tests tend to overestimate the unconfined compression strength of the soil samples. CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 4.0 SITE OBSERVATIONS OF SURFACE CONDITIONS ALONG ALIGNMENT OF ROADWAY AND DESCRIPTIONS OF SUBSURFACE STRATIGRAPHY 4.1 DESCRIPTION OF SURFACE CONDITIONS ALONG ALIGNMENT OF ROADWAY The ground surface along the alignment of the proposed roadway consists predominantly of improved pastureland with isolated clusters of native trees. Undeveloped, vegetated woodlands lie generally to the northeast of the proposed roadway alignment. As can be seen from a review of the topographic information on Figure 2, the ground surface elevation along the alignment of the proposed roadway slopes toward the central portion of the roadway alignment near the location of ephemeral drainage ways. The elevations within the drainage ways appear to slope downward in a northerly direction towards the main channel of Bee Creek which is several thousand feet north of the project site. The ground surface slopes downward from approximately EL 312 Mean Sea Level (MSL) near the proposed intersection with Holleman Drive South at the B-1 location, to approximately EL 300 MSL near the central portion of the alignment at boring locations B-5, B-6, and B-7. The ground surface continues to remain relatively flat at elevations of approximately EL 298 to 299 MSL at the location of boring B-8 near the proposed intersection with Old Wellborn Road. 4.2 DESCRIPTION OF SUBSURFACE OR STRATIGRAPHICAL CONDITIONS The subsurface stratigraphy at the boring locations drilled along the route of the proposed roadway is presented in detail on the individual boring logs in Appendix A. The individual boring logs should be consulted for a detailed description of the stratigraphy at a particular location along the alignment of the proposed roadway. The engineering descriptions and classifications used to describe the stratigraphy followed the general guidelines of the previously referenced USCS as discussed in more detail in the following Section 4.2.1 of this report. A general and idealized description of the stratigraphy present at the boring locations based upon the USCS is presented in Section 4.2.2 of this report. 4.2.1 Soil Classification System Used in Subsurface Descriptions The soils comprising the proposed roadway subgrade and foundation zones were generally classified in accordance with the criteria set forth in the previously referenced USCS. Classification of the soils was primarily based upon the test results derived from the laboratory classification testing of the 12 CSC ENGINEERING e. ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX various soil strata within the stratigraphy, but visual and manual classification of some of the soils was also utilized in conformance with the procedures outlined in ASTM D 2488-00 — Standard Practice for Description and Identification of Soils (Visual -Manual Procedure). As previously discussed, 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 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 generally 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, and typically only of 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 (SC), 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 which the soil behaves as a non -plastic material (i.e., a "slightly moist' condition). The plasticity index (PI) 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 = PI). 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). Although the soil classifications utilized in the subsequently presented descriptions and discussions generally follow the criteria established by the current USCS, there is one exception with respect to clays. Under the current USCS, highly plastic clays with a LL value equal to or greater than 50 are given a CH designation (C for clays and H for high plasticity) and clays with a LL value of less than 50 are given a CL designation (C for clays and L for low plasticity). However, when Arthur Casagrande performed the original work for the soil classification system, he proposed an intermediate classification in which clays with LL values between 30 and 49 were termed CM (M for moderate) soils, or clays of moderate plasticity. Therefore, clays of moderate plasticity that have LL values ranging between 30 and 13 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, I N C . Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 49 have been designated by the letters CM in the following discussions in accordance with the originally proposed USCS. Although not adopted by ASTM, the CM designation is still sometimes used to describe in greater detail the soils with plasticities between the low and high ranges. 4.2.2 General Description of Subsurface Stratigraphy The subsurface stratigraphy was quite variable along the approximately 3,600 feet length of the roadway as might be expected. In general, the subsurface stratigraphy at most of the boring locations consisted of a surficial layer of silty sands that was underlain by both clayey sands and by clays of moderate to generally high plasticity. However, there were important variations in the subsurface stratigraphy both horizontally between the different boring locations and also vertically with depth at any single boring location. The subsurface stratigraphy can generally be divided into two (2) distinct zones: (1) a surficial zone that extended to depths ranging from 0.3 to 3 feet at the various boring locations and which generally contained granular soils that consisted of silty sands that typically exhibited a loose relative density; and (2) a near -surface or intermediate zone composed of strong clayey sands, sandy clays, and clays of moderate to high plasticity that extended from immediately below the bottom of the surficial zone to the maximum exploration depths ranging from 6 to 10 feet below the surface at the various boring locations. Each of these zones is described in more detail in the following sub -sections of this report. Surfrcial Zone. The surficial zone extended from the ground surface to depths range from 0.3 feet to 3 feet at the boring B-1, B-2, B-3, B-4, B-5, and B-8 locations and consisted of silty sands. The sands were generally gray, to tan and gray, to brown in color. Laboratory classification tests were performed on samples of soil recovered from the surficial zone. The laboratory classification tests indicated that the percent fines within the soils was high and ranged from 33.5 to 36.8 percent. Since fines are described as silt and clay sized particles, the percentage of the soil samples that are not considered as fines will represent the sand and gravel portions of the samples, with the sands generally being much more common than the gravels. Therefore, the samples of the surficial zone soils that were tested in the laboratory exhibited a wide variation in sand content that ranged from 63.2 percent (100 percent total soil sample — 36.8 percent fines = 63.2 percent sands) to 66.5 percent (100 percent total soil sample — 33.5 percent fines — 66.5 percent sands). As previously discussed, the fines represent either silts or clays. These surficial zone soils were essentially non -plastic, indicating that they were comprised primarily of silt. The sands therefore classified as SM type soils under both the originally proposed USCS and the current USCS. Near -Surface or Intermediate Zone. The near -surface or intermediate zone extended from immediately below the surficial zone to depths ranging from 6 to 10 feet at the boring locations. The soils 14 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, I N C . Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX present within the near -surface or intermediate zone ranged in color from gray, to tan, to tan and brown. The soils within the near -surface or intermediate zone typically consisted of clayey sands, sandy clays, and clays of moderate to high plasticity. The results of the laboratory classification tests performed on samples of the clayey soils of the near -surface or intermediate zone indicated that the clays exhibited LL values that varied widely from 44 to 65, although most of the LL values were above 50. The corresponding PI values ranged from 26 to 44 with most of the PI values being above 30. The measured percentage of fines in the clays also generally varied widely from 50.4 to 72.7 percent. Therefore, the clay samples exhibited a wide variation in sand content that ranged from 27.3 to 49.6 percent. The laboratory tests results indicated that the majority of the clays classified as clays of high plasticity, i.e., as CH type soils both the originally proposed USCS as well as the current USCS. Some of the soils also classified as clays of low plasticity, or CL type soils under the current USCS, or as clays of low medium plasticity, i.e., as CL to CM type soils, under the originally proposed USCS. The results of the unconfined compression test and the pocket penetrometer tests indicated that the consistency of the clays ranged from very stiff to hard and were generally hard throughout the soil profile. The results of the laboratory classification tests performed on the granular formation of the near - surface or intermediate zone indicated that percentages of fines ranged from 33.8 to 48.0 percent which corresponded to percentages of sand ranging from 52.0 to 66.2 percent. The fines generally consisted of silts as indicated by the relatively low LL values of 16 to 29 and the corresponding relatively low PI values of 3 to 14. The soils therefore generally classified as SC type soils, i.e., as clayey sands under both the current and the originally proposed USCS. The relative density of the sand formations was estimated from the results of the SPTs to be medium dense. 4.2.3 Limitations of General Description of Subsurface Stratigraphy The previously described generalized stratigraphy was utilized in the analysis as described in subsequent sections of this report. As previously indicated, it should be recognized that there may be some variations in the generalized stratigraphy between the boring locations along the length of the proposed roadway alignment. Furthermore, subsurface conditions are known to be variable in proximity to drainage ways. Consequently, soil conditions encountered along the portions of the proposed roadway alignment in proximity to the planned crossing of the existing drainage way may vary from the conditions encountered at the boring locations drilled at other portions of the drainage way. 4.2.4 Water Level Observations As previously discussed, all of the borings were advanced using dry auger drilling techniques to the maximum depths of exploration which varied from 6 to 10 feet below the existing ground surface. No 15 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX ground water was observed in any of the eight (8) roadway boreholes either during drilling or immediately following completion of the drilling operations. All of the boreholes were subsequently filled following completion of the ground water observations as a safety measure for animals and/or pedestrians crossing the drill site. The borings were filled with soils cuttings. Therefore, longer term ground water readings could not be obtained for the project. It is also worth noting that there were some granular soils, i.e., silty sands or clayey sands, encountered in the surficial zone at most of the boring locations and also in the near -surface or intermediate zone at some of the boring locations. Sand seams were also present in some of the clay formations comprising the near -surface or intermediate zone of the stratigraphy. Sand strata and sand seams are significant in that they are typical of water bearing zones that can hold and/or transmit ground water. In addition, seams of sands and fissures or cracks in the clay formations can also be sources of ground water. Consequently, it is possible that although no ground water was present within the depths of exploration at the time of the field study, some ground water could be encountered in the sand strata and within the sand seams or fissures present within the clay formations at the time of construction, especially if some of the climatological conditions favorable to ground water development as discussed in the following paragraph are present. It is important to recognize that ground water elevations may vary both seasonally and annually. As previously indicated, the absence of ground water at the time of the field study or the presence of ground water at specific observed depths does not mean that ground water will not be present or will be present at the same observed depths at the time of construction. Ground water elevations at any site are known to fluctuate with time and are dependent upon numerous factors. Ground water levels can be af- fected by such factors as the following, among others: (1) the amount of precipitation in the immediate vicinity of the project site and in the regional ground water recharge area; (2) the amount of infiltration of precipitation through the surface and near -surface soils; (3) the degree of evapotranspiration from surface vegetation at the project site; (4) the water levels in adjacent bodies of water, such as the un-named tributary of Bee Creek; (5) any dewatering operations on adjacent sites; and (6) the construction and post - development site drainage schemes which will influence the volume of storm water runoff directed towards, around, or away from the project site. The amount of precipitation that occurs immediately prior to the start of construction and also during the time frame of construction is especially important and will strongly influence ground water conditions that are experienced during construction operations. Furthermore, it should be understood that ground water information determined during this study was obtained to evaluate potential short term impacts on construction activities and should not be considered a comprehensive assessment of ground water conditions at the site. Consequently, as 16 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, I N C . Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX previously emphasized, the ground water levels observed at the time of the field investigation may vary from the levels encountered both during the construction phase of the project and also during the design life of the proposed project. Also as previously discussed, the long-term ground water levels may be somewhat dependent upon any changes to the existing storm water runoff patterns at the site caused by construction of the subject project or adjacent projects. If the long-term variation of the ground water level is critical to some design aspect of the proposed project, an extended hydrogeologic study involving the installation and long-term monitoring of piezometers should be undertaken to better define the pertinent ground water conditions at the site that may influence the design. 17 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC, Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 5.0 GENERAL PAVEMENT SYSTEM RECOMMENDATIONS This section of the report presents our analysis and recommendations for foundation support of the paving system for the proposed roadway. 5.1 GENERAL ANALYTICAL PROCEDURES FOR DESIGN OF PAVEMENT SECTION FOR PROPOSED ROADWAY The American Association of State Highway and Transportation Officials (AASHTO) design procedure was used to compute the pavement thickness requirements for the rigid and flexible pavement sections being considered for the proposed roadway. We have assumed that both pavement sections would include a chemically -stabilized subgrade soil layer. The anticipated traffic loads and the load - carrying characteristics of the expected subgrade soils were used to determine required constructed thicknesses for both the rigid pavement section and the flexible pavement section as discussed in the following sub -sections of this report. 5.2 SUBGRADE CLASSIFICATION 5.2.1 General Discussion of Anticipated Pavement Subgrade Soils As previously indicated in Section 1 of this report, the final grading plans for the proposed roadway improvements are not known at the present time. However, the preliminary site grading plans indicate that most of the length of the roadway will only require less than 2 to 3 feet of excavation or fill placement in order to achieve final subgrade elevations, except at the proposed drainage way crossing. Approximately 4 to 5 feet of fill will be needed for limited lengths of the proposed roadway at the planned crossings of the un-named tributaries of Bee Creek. The fill will be placed as an earthen "embankment" that will permit the elevation of the roadway pavement surface above low lying areas. We believe that "embankment' fill soils will be placed over the existing soils in the drainage channels, unless the existing soils are not sufficiently strong to be able to support the proposed "embankment." Consequently, we anticipate that the proposed roadway will be constructed on both natural soils and on an "embankment' of fill soils in the area of the proposed drainage way crossings. As previously indicated, based upon the borings drilled along the route of the proposed roadway, silty sands will be present in the surficial zone of the stratigraphy that extends to depths ranging from 0.3 to 3 feet below the existing ground surface at the various boring locations along portions of the roadway. These fine silty soils can develop very poor load support characteristics and can be very difficult to 18 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX compact if they are in a very moist to wet condition at the time of construction. Very moist to wet silty and fine sandy soils will tend to exhibit "pumping" characteristics as subsequently discussed. The soils underlying the surficial sands generally consisted of clays that are generally of moderate to high plasticity. The natural clays are expected to have relatively high PI values of 30 or higher, although the PI of some of the granular soils of the near -surface or intermediate zone may be as low as 3 (boring B-7 location). We also anticipate that the embankment at the drainage way crossing will be constructed of imported clay soils of moderate to high plasticity. Recommended properties of the clay fill soils are presented in Section 6 of this report. The embankment itself will be constructed over existing soils that will represent the subgrade for the earthen embankment (but not the pavement section subgrade). Potential problems with both the roadway subgrade soils and the embankment subgrade soils that could adversely impact the construction of the proposed embankment are discussed in the following sub- section of this report. In the case of both the natural soils and the imported fill soils, we anticipate that the subgrade soil layer for the proposed pavement section will be improved when the soils are chemically stabilized and compacted as subsequently recommended. The chemically stabilized and compacted subgrade soils will provide adequate support for the proposed pavement section. 5.2.2 Potential Problem Areas Of Existing Soils Within the Planned Subgrade Zone of the Pavement and Embankment The nature of the surficial soils of the stratigraphy along the alignment of the proposed roadway is very important since these soils will impact the design and construction of the both the roadway pavement and the earthen embankment being constructed as part of the proposed roadway project. For example, as previously discussed in Sections 4.2 and 5.2.1 of this report, the surficial soils at most of the boring locations consisted of granular soils with a high percentage of silts and/or fine sands. The surficial zone soils generally extended from the existing ground surface to depths ranging from approximately 0.3 to 3 feet. Surficial silty and fine sandy soils of low cohesion can be difficult to process and compact if the soils are in a very moist to wet condition at the time of construction. Surficial silts and fine 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 void spaces of the silt or fine sand soil matrix and not to the soil structure itself. Thus, the compaction energy is "absorbed" by the water within the void spaces 19 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Repoli of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX of the soil structure and not by the actual soil structure. 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 soil water that resembles a "water bed" effect. As a result, the silts and fine sands can remain in a loose condition and will not provide adequate subgrade support for either the roadway pavement or the roadway embankment. Furthermore, although the clay soils of the near -surface or intermediate zone along the drainage ways at the boring B-5, B-6, B-7 locations were relatively strong and exhibited consistencies in the range of very stiff to hard, it is possible that weaker clays with a soft to firm consistency could be encountered across the bottom of the drainage channel in some areas of the proposed earthen embankment location. Consequently, we recommend that if such weak and difficult to process soils are encountered during construction, it will likely be necessary to strip these soils from the areas of proposed construction and replaced them with select roadway embankment fill soils as subsequently specified. Consequently, we believe that it would be prudent to ship the existing weak surficial soils, which are present either along the planned roadway alignment or in the area of the embankment at the drainage way crossings, from the site to at least the previously indicated depths of the surficial zone at the various boring locations. Deeper depths of stripping may be required along portions of the roadway alignment between the boring locations to effectively remove all of the weak surficial soils. The stripped soils should be replaced with select roadway embankment fill soils as subsequently defined in this report. If the existing weak surficial soils and any associated organic matter are not removed, they may be very difficult to process and compact if they are wet at the time of construction. In addition, any ground - supported roadway elements, such as the embankment that are supported on such soils, could experience appreciable movements due to the weak and compressible character of the subgrade soils. The movement could result in some distress to the supported roadway pavement system. 5.2.3 Chemical Stabilization of Roadway Pavement Subgrade Soils The addition and processing of chemical -stabilizing agents, such as hydrated time, fly ash, and/or Portland cement, into the pavement subgrade soils can increase the strength and volumetric stability of the soils within the treated subgrade zone, especially with compaction of the chemically -altered soils. Consequently, we strongly recommend that the subgrade soils for the proposed roadway pavement section be chemically stabilized. If the subgrade soils are not chemically stabilized, there may be a significant loss of subgrade support if the unstabilized soils become wet and saturated during the design life of the pavement system. Accordingly, we have assumed in our analysis that the subgrade soils will be chemically stabilized and compacted to a depth of at least 8 inches below the surface of the subgrade layer to improve the support capacity for the subgrade layer. 20 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, I N C . Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX The chemical used to stabilize the subgrade soils will depend upon the character of the subgrade soils. If the subgrade soils consist of clays or sandy clays of moderate to high plasticity with a minimum PI value of 20 as anticipated over the major portion of the roadway, these types of soils can readily be stabilized by the addition of hydrated lime. Details concerning material characteristics and placement procedures for a lime -stabilized subgrade are presented in Section 6.6 of this report. However, it should be noted that soils with PI values lower than 20 may also be encountered in some areas along the proposed roadway alignment. Subgrade soils with PI values between approximately 8 and 19 (inclusive) should be stabilized with a mixture of Type A hydrated lime or Type C quick lime and Class C fly ash. Similarly, if subgrade soils have PI values of 7 or less, they should be stabilized with either Class C fly ash or with Portland cement mixture. Specific percentages of the stabilizing agents for preliminary planning purposes and other recommendations for chemical stabilization of the subgrade soils are presented in Section 6.6 5.3 PROJECTED TRAFFIC VOLUMES AND CHARACTERISTICS The traffic volume used in the pavement design analyses for the proposed roadway was based upon the assumptions outlined in Section 1 of this report. The characterization of the vehicles that are believed to comprise the traffic using the proposed roadway was also presented in Section 1. In addition, other traffic information that was required for the design of pavement sections was discussed in Section 1 of this report. The loading for all the different types of vehicles that may travel over the paved surface of the roadway is typically expressed in terms 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 l 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 30-year design period for the rigid pavement system and for 20-year design period for the flexible pavement system based upon the estimated average daily traffic volume and other traffic characteristics listed in Section 1. 21 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 5.4 PAVEMENT SECTION THICKNESS REQUIREMENTS The pavement calculations utilized the previously discussed traffic conditions as expressed by the ESALs, the previously indicated subgrade strength properties (assuming that the subgrade soils will be chemically stabilized and compacted to a minimum depth of 8 inches in accordance with the provisions of a subsequent section of this report), and assumed typical paving material strength properties and reliability factors. The required total pavement thicknesses were computed for both rigid and flexible pavement systems and are presented separately in the following tables. The recommended rigid pavement section for the proposed roadway consists of a two -layer system that incorporates a surface course of PCC and a subgrade layer composed of chemically stabilized and compacted soils. The minimum thicknesses for the various layers of the rigid pavement section are presented in the following Table 2. Table 2. Pavement Thickness Schedule for Conventionally Reinforced and Jointed PCC Thickness (inches) """' I Material Description .l 0 Note 2 I Reinforced Portland cement concrete surface course "°" a 8.0 Compacted chemically -stabilized subgrade soils "" 4 15.0 Total constructed pavement thickness Notes: L 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 applicable requirements. 2. The BtyatvlCollege Station Unified Design Guidelinesfor.Streets and Alleys (2009) specifies a minimum "concrete pavement' thickness of 8 inches and a minimum subgrade treatment of"6-in Lime -Stab." For streets classified as collectors. 3. Concrete assumed to have a minimum modulus of rupture (as determined in a third point beam loading test) corresponding to 650 psi (approximately equivalent to concrete with a 28-day compressive strength of 4,000 psi). 4. The requirements for compaction and chemical stabilization of the subgrade soils are presented in Section 6. The recommended pavement section presented in the table represents the minimum required thicknesses for the planned roadway. It should be noted (as indicated in the footnotes to the table) that the Biyan/College Station Unified Design Guidelines for Streets and Alleys (2009) may specify a greater thickness of pavement section for certain street classifications than indicated by the calculated minimum required thicknesses. Also note that tie-in sections to existing streets or highways should be made in accordance with applicable city/state design criteria if these section thicknesses are greater than indicated in the table. All of the 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 PCC paving be reinforced with a minimum of #4 reinforcing steel bars placed at the mid -point of the paving section at spacings corresponding to 18 inches 22 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX on -center, each way as specified in the Bryan/College Station Unified Construction Details for Streets (2009), which is hereinafter cited as B/CS Unified Details. In addition, adequate jointing of the concrete pavement should be included in the design and construction of the pavement system. Concrete pavement should be segmented by the use of control or contraction joints placed a recommended spacing of 12 feet center to center and a maximum spacing of 15 feet. Keyed and doweled longitudinal joints should be located in all roadway sections greater than one lane (10 to 13 feet) in width. Expansion and/or construction joints should be placed at a maximum spacing of 120-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 permanent structures (such as retaining walls or drainage inlets). All joints should be sealed with Sonoborn Sonolastic SLI (or equivalent) to minimize infiltration of surface water to the underlying subgrade soils. Please note that the B/CS Unified Details may require a closer spacing of joints titan recommended in this report. If the proposed roadway will have to carry a significant percentage of truck traffic, we recommend that strong consideration be given to the use of a rigid pavement section for the heavy traffic lanes since the PCC section tends to require less maintenance under moderate to heavy truck loading than flexible pavement systems. If it is anticipated that the truck traffic will exceed the previously indicated volumes and vehicle weights, then the wearing surfaces of the rigid pavement section should be increased to 8 inches. If it is determined that a flexible pavement system would provide the more economical section for the proposed roadway, we recommend the pavement section outlined in Table 3 be employed for the roadway. Table 3. Pavement Thickness Schedule for Hot -Mix Asphalt Concrete (HMAC) Thickness (in) I Material Description 5.0 HMAC (Item 340), To consist of 2" of Type D and 3" of Type C Note 2 8.0 Compacted crushed limestone base (Item 247), Type A, Grade 1 Notes 2,3 8.0 Compacted chemical] -stabilized subgrade soils N°`° 4 _ 21.0 Total constructed pavement thickness Notes: 1. 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 constructed of rigid pavement. 2. Item number refers to sections of the Texas Department of Transportation Shmdard Specificationsfor Construction and Maintenance of Highways, Streets, and Bridges, June I, 2004. 3. The base course should be compacted to at least 95 percent of the maximum density achievable in the Modified Proctor Moisture -Density (Compaction) test (ASTM D 1557) at moisture contents in the range of the optimum moisture content to 4 percent above the optimum moisture content, inclusive. 4. The requirements for compaction and chemical stabilization of the subgrade soils are presented in Section 6. 23 050 ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Repoli of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX The edges or periphery of pavement sections are a natural weak point due 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 indication 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 PCC curb and gutter. In addition, we recommend that the exterior boundary of the chemically -stabilized subgrade layer extend at least 2 feet beyond the edge of the pavement surface layer. These extensions will help to minimize the formation of edge cracks in the pavement system due to either a lack of boundary support under wheel loading as previously 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. 5.5 PAVEMENT SYSTEM DRAINAGE AND MAINTENANCE 5.5.1 Pavement Drainage The control of surface drainage and sometimes even ground water drainage is a critical factor in the performance of a pavement system. Adequate provisions for surface and subsurface drainage should be included in the pavement design scheme. Drainage provisions should include the following, among other items and features: a steeply graded pavement surface to quickly transport storm water to collection or discharge points that drain away from the paved areas; an adequate number of storm water catch basins or curb inlets in the paved areas to capture the storm water; and adequately sized storm sewer piping. In addition, landscaping or "greed" areas and other potential sources for moisture infiltration within the limits of the paved areas should be minimized. The landscape waterings in these "greed' areas should be carefully controlled to minimize the introduction of excess moisture into the pavement subgrade soils. 5.5.2 Pavement Maintenance The owner should institute and budget for a regular maintenance program for the paved areas. 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 storm water infiltration into the underlying pavement system layers and subsequent degradation of performance. Sealants that can withstand exterior exposures, such as Sonoborn SL-I for rigid pavements 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 patching and overlaying of the pavement system should be anticipated over the expected life of the pavement. 24 CSC ENGINEERING E ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 6.0 SITE DEVELOPMENT AND CONSTRUCTION CONSIDERATIONS General construction recommendations for various aspects of the construction phase of the proposed project are offered in the following sub -sections of this report. These items should be considered ,'minimum standards" and are intended to be used in conjunction with the project specifications developed by the design engineer. 6.1 CLEARING OF EXISTING SURFACE VEGETATION AND STRIPPING OF SURFICIAL ORGANIC MATERIALS The existing vegetation, which includes grass and any bushes or trees, as well as all organic topsoils, should be stripped from the areas of proposed paving and the proposed roadway embankments in order to reduce the potential detrimental effects of these organic materials on the proposed pavement systems and roadway embankments. In addition and as previously discussed, we recommend that all of the potentially weak surficial zone soils with high percentages of fines and low clay contents be stripped from the construction areas. Special attention should be directed during the stripping operations to the removal of all roots. It is very important to remove the major root systems associated with any large trees that are either present on the site or which may have been previously present on the site. Removal of the root systems of large trees should include all desiccated soils present within the "root bulbs" of such trees. The clearing and stripping operations should also include the removal of any existing organic materials or "muck" that may be present in the existing drainage ways that cross the proposed roadway alignment. Any identified organic materials or "muck" should be excavated and removed from the site. The excavated organic materials and topsoils should either be removed from the site or stockpiled and used in landscaped areas that will not have to support structural elements. If the existing organic materials and topsoils are not removed from the site prior to construction of the paved roadway area and embankments, it is possible that these existing materials will interfere with the proposed construction and could potentially adversely impact the future performance of the proposed roadway pavement systems and embankment. 6.2 PROOF ROLLING OF ROADWAY EMBANKMENT SUBGRADE SOILS All surfaces exposed after the stripping of the vegetation and topsoils and planned for fill placement should then be proof -rolled with a 20-ton pneumatic roller or equivalent vehicle in order to identify all soft or weak areas of soils, especially in the areas of the existing drainage ways. Any soft or 25 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX weak soils identified during the proof rolling process should be excavated down to "firm" ground. The excavated soils should be removed from the project site and replaced with compacted select embankment fill. The embankment fills should meet the material characteristics and be placed in accordance with the recommendations subsequently presented in Section 6.5. Over -excavated areas or areas of depressions created by the removal of tree root bulbs or existing utilities that are to be replaced or relocated should also be backfilled with compacted select roadway embankment fill. The reasons for proof -rolling of the subgrade is that some soils have been found to compact to minimum density requirements but to still exhibit "pumping" tendencies. Proof -rolling of the subgrade should identify the soils that have a tendency to pump so that they can be removed and replaced with more suitable foundation soils 6.3 COMPACTION OF SUBGRADE SOILS IN PAVEMENT AREAS The subgrade soils in areas planned for fill placement, which includes the roadway embankments, should be compacted following proof -roll testing to at least 95 percent of the maximum density determined by the Standard Proctor compaction test (ASTM D 698-07e1 — Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12, 400 ft-lbf/ft3 (600 W-mhn')) at moisture contents in the range of the optimum moisture content (OMC) to 4 percent above the OMC, inclusive. Compaction characteristics of the subgrade layer in the general fill areas or in the embankment areas should be verified by in -place density tests. The tests should be performed at an average rate of one test for every 5,000 sq ft in the planned embankment base area or for every 300 linear feet of roadway alignment, whichever criterion produces the greater testing frequency. 6.4 SITE GRADING AND DRAINAGE As previously mentioned, the surface soils in some areas of the project may consist of silt and sands that are in a wet condition at the time of construction. As discussed in Section 5.2 of this report, these silty and sandy soils will exhibit poor load -bearing characteristics with increased moisture contents, such as could occur after periods of heavy and/or prolonged precipitation. Consequently, the contractor should make early efforts to crown and grade the surface of the paved areas as soon as possible following stripping of the surface vegetation to promote positive drainage away from proposed embankment and paved areas during construction. Inadequate site preparation and protection of roadway pavement and embankment subgrade soils has been associated with numerous distressed paving systems in this area since the structural layers of the pavement and the roadway embankment are supported on the subgrade soils. In no event should water be allowed to pond next to the paved areas or the area of the embankment. Also, consideration should be given to the stabilization of the exposed soils within ground -supported CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS. INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX pavement areas or in embankment fill areas as soon as possible. Weak or unsuitable surficial soils in these areas should be removed and replaced with select roadway embankment fill soils as previously recommended and as subsequently detailed. The replacement scenario should be consistent with compaction requirements outlined in Section 6.5. As previously discussed, storm water generated by development of the project should be managed to ensure that precipitation runoff does not pond in the work areas but is routed away from the construction areas and discharged downstream of the work areas into existing storm drainage systems. Provisions should be made to the maximum extent possible to discourage utility, trenches serving as pathways for water to migrate from outside to beneath the paved areas. Sloping the bottom of the utility trench away from the paved areas and the use of anti -seep collars (such as thin, vertical "sheets" of compacted clay) should be considered. 6.5 SELECT ROADWAY EMBANKMENT FILL SOILS MATERIAL CHARACTERISTICS AND PLACEMENT PROCEDURES 6.5.1 General Any fill used to adjust grades in the paved areas, to construct the roadway embankments, to fill existing depressions, or to fill over -excavated areas should conform to the requirements of select roadway embankment fill. Select roadway embankment fill is defined as materials that meet the following criteria with respect to material and placement requirements for the fill: Selected fill material used for roadway embankment construction should consist of a generally moderate plasticity material with a PI between 20 and 40, inclusive, and a LL value of between 35 and 60, inclusive. The select fill soils should classify as clays of moderate plasticity or CL type soils under the current USCS (and as CM type soils under the originally proposed USCS), or as clays within the lower range of high plasticity, or in the lower range of CH type soils under both the current and the originally proposed USCS. The minimum PI value of 20 should help to discourage storm water from infiltrating into the soils of the embankment or into the pavement subgrade. • Soils containing an excessive amount of silt (i.e., greater than approximately 20 to 25 percent) should not be used unless there is a corresponding percentage of clay to "balance" the potential negative effects of the silt. Soils classifying as ML, OL, MH, OH, or PT type soils under the previously referenced USCS (ASTM D 2487) shall not be used as fill. • The fill soils placed in embankments and exposed to impounded water should also be characterized as non -dispersive soils. The non -dispersive character of the soils should be documented through the performance of pinhole dispersion tests (ASTM D 4647). • Compaction of the structural fill should be at moisture contents in the range of the OMC to 4 percent above the OMC, inclusive, and should be in lifts not to exceed 6 27 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX inches in compacted thickness. Density should be at least 95 percent of the maximum dry density as determined by the previously referenced Standard Proctor compaction test, ASTM D 698. • Compaction characteristics of the roadway embankment 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 5,000 ft2 of plan roadway area or every 300 linear feet of roadway, whichever produces the greater frequency of testing. 6.6 PAVEMENT SUBGRADE STABILIZATION REQUIREMENTS The pavement design recommendations presented in a previous section were developed assuming that the subgrade soil layer would be chemically stabilized and otherwise prepared as listed below and that the various materials comprising the pavement section would comply with the material requirements and would 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 embankment areas 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 stabilization of 8 inches is recommended. • The pavement subgrade soils will likely consist of clays of moderate to high plasticity with PI values = or > 20). These soils should be stabilized with Type A hydrated lime or Type C quick lime. For preliminary planning purposes, the amount of lime to be added to the soils can be estimated to be approximately 6 percent. The percentage is measured with respect to dry soil unit weight. For example, for a subgrade soil layer of 8 inches in thickness that has a unit dry weight of approximately 100 pcf, approximately 36 lb/ydz of hydrated lime should be used in the mixture. • If any of the pavement subgrade soils consists of clayey sands or very sandy clays of intermediate plasticity (i.e., 7 < PI < 20), these intermediate plasticity soils should be stabilized with a mixture of Type A hydrated lime or Type C quick and Class C fly ash in equal pails. For preliminary planning purposes, we recommend that 3 percent hydrated lime and 3 percent fly ash be used as the stabilizing mixture. The percentages are measured with respect to dry soil unit weight. For example, for a subgrade soil layer of 8 inches in thickness that has a unit dry weight of approximately 100 pcf, approximately 18 lb/yd2 of hydrated lime and 18 lb/yd2 of fly ash should be used in the mixture. • Similarly, in the unlikely event that nearly "pure" granular soils of low plasticity (i.e., PI < or = 7) are present in some of the areas to be paved, these soils should be stabilized with Class C fly ash at a rate of 12 percent as measured by dry weight of soil (72 Ib/yd' for a lift of 8 inches thickness). Alternately, approximately 5 percent Type I Portland may be used in lieu of the fly ash. • Stabilization procedures should be in accordance with the Texas Department of Transportation's Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges (June 2004) Item 260, Lime Treatment For Material Used As Subgrade (Road Mixed), Type A Treatment specification, or Item 265, m CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 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 percent 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 fill soils meeting the requirements presented herein should be at moisture contents within the range of the OMC to 4 percent above the OMC, inclusive. Density should be at least 98 percent of the maximum dry density as determined by the previously Standard Proctor compaction test, ASTM D 698. • The percentages of lime, fly ash and cement to be admixed with the subgrade soils as previously listed are presented for preliminary planning proposes only and should be confirmed by specific laboratory tests performed at the time of construction. 6.7 FLEXIBLE AND RIGID PAVEMENT SECTION MATERIALS REQUIREMENTS The pavement materials used for the proposed roadway construction should comply with the material requirements outlined in the Texas Department of Transportation Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges (2004) (hereinafter abbreviated as SSCMHSTB) and in the current version of the joint Bryan/College Station Unified Technical Speefeations (2009). More specifically, the following pavement material types, properties, and placement procedures are recommended for the various pavement section materials. 6.7.1 Flexible Pavement Base Course and Surface Course Base Course The base course in a flexible pavement section should consist of crushed limestone aggregate base that meets or exceeds the requirements of SDHPT Item 247 — Flexible Base, Grade I. Compaction of the base material should be at a moisture content that is at the optimum moisture content to 4 percent above the OMC, and to 95 percent of the maximum dry density as determined by the Modified Proctor moisture -density relationship test (ASTM D 1557 — Standard Test Methods for laboratory Compaction Characteristics of Soil Using Modified Effort (56, 000 ft-Ibf/f3 (2, 700 kN-m/m'))). Surface Course (HMAC) The HMAC surface course should comply with SDHPT Item 340, Type D. Hveem stability, as determined by ASTM D 1560, should be between 35 and 55. 6.7.2 PCC Pavement, Curb and Gutter, and Drainage Structures The concrete used for the construction of any rigid pavement sections and any curbs and gutters, as well as all drainage structures associated with the proposed roadway construction 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. 29 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX • Submitted mix designs should indicate that the aggregates have been tested in accor- dance with ASTM C 33 within a time period that does not exceed one year. • The concrete used in the pavement system should also have a minimum modulus of rupture of 650 psi (as determined using a third point beam loading test, ASTM C78- 08 — Standard Test Methodfor Flexural Strength of Concrete (Using Simple Bean? With Third -Point Loading), which roughly corresponds to a minimum 28-day compressive strength of 4,000 psi as determined in accordance with ASTM C 39. • The compression strength of the concrete should be verified by testing sets of concrete cylinders. 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 of cylinders being cast during each placement day. One of the cylinders should be tested for compressive strength after a time lapse of 7 days following placement 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. • If fly ash is used in the concrete, the replacement percentage should not exceed 20 percent of the total cementitious material. • An appropriate percentage of air entrainment admixture should be added to the concrete that is exposed to the weather elements. 30 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 7.0 BASIS OF RECOMMENDATIONS The recommendations contained in this report are based in palm 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 or designer should convey the correct or additional information to CSC so that CSC may evaluate the correct or additional information and determine if any of the recommendations presented in this report should be modified The field exploration which provided information concerning subsurface conditions was considered to be in sufficient detail and scope to form a reasonable basis for the conceptual planning and final design of the foundation systems for the proposed roadway project. Recommendations contained in this report were developed based the subsurface conditions encountered at the boring locations and upon generalizations of the subsurface stratigraphy based upon the assumption that the generalized conditions present at the boring locations are continuous throughout the areas under consideration. It should be noted that 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. Therefore, we recommend that experienced geotechnical personnel be employed to observe con- struction operations and to document that conditions encountered during construction conform to the assumed generalizations which formed the basis for the recommendations presented in this report and any supplemental reports. Furthermore, the construction observers should document construction activities and field testing practices employed during the earthwork and foundation construction phases of the project. The owner's construction project manager should review the results of all field and laboratory construction materials tests for conformance with the recommendations presented in this geotechnical report and in the project construction documents and should verify that the assumptions made in design conform to as -constructed conditions. Questionable construction procedures and/or practices and non- conforming test results should be reported to the design team, along with timely recommendations to solve any issues raised by the questionable procedures, practices, and/or test results. 31 CSC ENGINEERING & ENVIRONMENTAL CONSULTANTS, INC. Report of Subsurface Exploration & Geotechnical Study Deacon Drive Extension; College Station, TX 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. This report was prepared for the subject roadway project specifically identified in the report. Information presented in the report shall not be used for structures other than the roadway structure or for other projects in the area of the subject project without the express written permission of the geotechnical engineer. 32 G�L 9-20-12 City of College Station 1101 Texas Avenue College Station, Texas 77842 EAST TEXAS OFFICE GOODWIN • LASITER INC. [936] 637- � FAX [936] 637-6330 6330 ENGINEERS • ARCHITECTS • SURVEYORS CENTRAL TEXAS OFFICE [S79] 776-9700 FAX (97S] 776-3838 RE: LETTER ACKNOWLEGING CITY STANDARDS The Barracks II — Phase 101, College Station, TX Dear Ms. Cotter: The purpose of this letter is to acknowledge that the construction plans for the water, sanitary sewer, streets and drainage for the above -referenced project, to the best of my knowledge, do not deviate from the B/CS Design Guideline Manual. I also acknowledge, to the best of my knowledge, that the details provided in the construction plans are in accordance with the Bryan/College Station Standard Details. Sincerely, John Rusk, PE Project Engineer 4077 CROSS PARK DRIVE • SUITE 100 • BRYAN, TEXAS • 77BO2 • ctex@goodwlnlasiter.ocm TBPE #413 1609 S. CHESTNUT • SUITE 202 • LUFKIN, TEXAS - 75901 - admin@goodwinlasiter.comes.;61418f40021CO"Spondenc V-etter Acknowleging City Sfanderds.dw ENGINEERING COMMENTS NO. 2 1. FYI -Welded wire fabric not allowed for public paving infrastructure or paving in public ROW. Welded wire fabric still appears in Note 4. 2. FYI -Street lights are normally required at all street intersections and access ways, in cul-de- sacs and generally at 300-foot intervals. 3. Street Sign Table — Sign No.4 should read Cullen Trail 3300. 4. Provide BTU agreement for street lights and electric service. 5. Trash pads shall not be located on top of stormwater inlets or utility services. 6. Structural fill required on utilities under trash pads. 7. Verify there is adequate vertical separation between trash pad footing and utilities beneath. Several locations seem deficient, especially over storm sewer pipe. 8. Trash pad located on east side of Cullen Trail closest to Capps Drive is in visibility sight triangle and will have to be relocated. 9. In looking at Phase 100 final product for sidewalks and driveways, there is not a clear enough distinction between the sidewalk and driveway. In many instances the sidewalk was completely blocked by vehicles parked in the driveways. Please propose something to better define the sidewalk limits. 10. Confirm that the 15' Drainage Easement width between structures is sufficient to accommodate equipment, bank slopes, OSHA separation, and area for soil stockpile for future maintenance and repairs. 11. Did not see documentation regarding USPS cluster mailbox locations that was noted as being attached. 12. Signage will need to be erected notifying construction vehicles that Keefer Loop is not a construction exit. Approved construction exit is at Deacon. 13. Regarding cross -lot drainage; The concern is more for future individual lot ownership and drainage issues that develop between neighbors. If there is no defined buffer or easement it is more difficult to private property owners to get improvements or corrections made on property owned by someone else. Reviewed by: Carol Cotter Date: October 16, 2012