ADDENDUM No. 2 BID NO THOMPSON CREEK SUBSTATION DRIVEWAY IMPROVEMENTS PROJECT

Transcription

1 205 E. 28 th St. <77803> P.O. Box 1000 Bryan, TX Phone: FAX: November 2, 2015 ADDENDUM No. 2 BID NO THOMPSON CREEK SUBSTATION DRIVEWAY IMPROVEMENTS PROJECT Please be advised of the following information to the bid request package referenced above: Clarifications (Questions & Answers): Below Geotechnical Report: Attached Clarifications (Questions & Answers): 1. Question: On page 65 of the bid specs it states that substation fence shall be a minimum of 8 feet high (7feet of fabric and a 1 -foot extension of barbed wire). But on the miscellaneous detail page it states a 6ft high fence (7ft overall). Please clarify. Answer: The fence surrounding the WWTP is six feet high woven wire, plus three strands of barbed wire, per the detail on MD-01. The fence surrounding the electrical substation is seven feet high woven wire, plus barbed wire and razor wire, per sheets BTU-TC-601 and BTU-TC Question: The plans state that the contractor is responsible for mitigation of weak subgrade areas (GN-02: Earthwork and Paving Note 3)-No Separate Pay, but the bid specs page 97 of 153 states that the contractors shall only be responsible for the first 10 CY. Which is correct? Answer: The contractor is responsible for mitigating all weak subgrade areas, per GN-02: Earthwork and Paving Note 3. We regret any inconvenience this change may cause you in processing this bid request. This addendum shall be signed and included with your bid package as acknowledgement of the addendum. Failure to acknowledge and submit any addenda may be cause for the bid to be rejected. Bidder Acknowledgement Signature: X Sincerely, Phebe Mosley - BTU Addendum Two # Page 1 of 27

2 Geotechnical Engineering Report Proposed Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A Prepared for: Bryan Texas Utilities Bryan, Texas Prepared by: Terracon Consultants, Inc. College Station, Texas Addendum Two # Page 2 of 27

3 April 15, 2014 Bryan Texas Utilities 205 East 28 th Street Bryan, Texas Attn: Re: Mr. James Tanneberger Division Manager - Transmission Geotechnical Engineering Report Proposed Thompson Creek Bridge Brazos County, Texas Terracon Project No. A Dear Mr. Tanneberger: Terracon Consultants, Inc. (Terracon) is pleased to submit our geotechnical engineering report for the project referenced above in Brazos County, Texas. We trust that this report is responsive to your project needs. Please contact us if you have any questions or if we can be of further assistance. We appreciate the opportunity to work with you on this project and look forward to providing additional geotechnical engineering and construction materials testing services in the future. Sincerely, Terracon Consultants, Inc. (Texas Firm Registration No.: F-3272) Joseph D. Hill, E.I.T. Senior Staff Geotechnical Engineer Alton G. Rogers, P.E. Senior Associate / Office Manager Enclosures Copies Submitted: (1) Bound & (1) Electronic Terracon Consultants, Inc Imperial Loop College Station, TX P [979] F [979] terracon.com Addendum Two # Page 3 of 27

4 TABLE OF CONTENTS Page EXECUTIVE SUMMARY... i 1.0 INTRODUCTION PROJECT INFORMATION Project Description Site Description SUBSURFACE CONDITIONS Geology Typical Profile Groundwater RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION Geotechnical Considerations Foundation Systems Design Recommendations Drilled, Straight-Shaft Foundations Construction Considerations Drilled, Straight-Shaft Foundations Foundation Construction Monitoring GENERAL COMMENTS... 8 APPENDIX A FIELD EXPLORATION Exhibit A-1 Site Location Plan Exhibit A-2 Boring Location Plan Exhibit A-3 Field Exploration Description Exhibits A-4 and A-5 Boring Logs APPENDIX B LABORATORY TESTING Exhibit B-1 Laboratory Testing APPENDIX C SUPPORTING DOCUMENTS Exhibit C-1 General Notes Exhibit C-2 Unified Soil Classification System Addendum Two # Page 4 of 27

5 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A EXECUTIVE SUMMARY This geotechnical engineering report has been prepared for the proposed construction of a new bridge spanning Thompson Creek, located southwest of the existing Thompson Creek Waste Water Treatment Plant, in Brazos County, Texas. Two test borings, designated B-1 and B-2, were drilled to depths of approximately 70 feet below grade (grade existing at the time of our field program) in the area of the proposed bridge. Based on the information obtained from our subsurface exploration, the site can be developed for the proposed project. A summary of our findings and recommendations is listed below. Groundwater was observed during dry drilling at borings B-1 and B-2 at depths that varied from about 41½ to 42½ feet below existing grade. A drilled, straight-shaft foundation system may be utilized to support the structural loads of the proposed bridge provided the subgrade is prepared as discussed in this report. Based on the subsurface conditions observed, the installation of drilled straight-shafts may require the use of temporary steel casing and/or the Slurry Displacement Method to help control groundwater seepage and sloughing of the sidewalls. This summary should be used in conjunction with the entire report for design purposes. Details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled 5.0 GENERAL COMMENTS should be read for an understanding of the report limitations. Responsive Resourceful Reliable i Addendum Two # Page 5 of 27

6 GEOTECHNICAL ENGINEERING REPORT PROPOSED THOMPSON CREEK BRIDGE BRAZOS COUNTY, TEXAS Project No. A April 16, INTRODUCTION Terracon Consultants, Inc. (Terracon) is pleased to submit our geotechnical engineering report for the proposed construction of a new bridge spanning Thompson Creek, located southwest of the existing Thompson Creek Waste Water Treatment Plant, in Brazos County, Texas. Two test borings, designated B-1 and B-2, were drilled to depths of approximately 70 feet below grade (grade existing at the time of our field program) in the area of the proposed bridge. This project was authorized by Mr. Gary Miller, General Manager for BTU, through signature of BTU s Contract for Professional Services on January 11, The project scope was performed in general accordance with Terracon Proposal No. PA , dated January 29, The purpose of this report is to describe the subsurface conditions observed at the two test borings drilled for this project, analyze and evaluate the test data, and provide recommendations with respect to: Site and subgrade preparation; and Foundation design and construction. 2.0 PROJECT INFORMATION 2.1 Project Description Item Project location Site layout Proposed improvements Grading Maximum loads (assumed) Planned foundation system Description See Appendix A, Exhibit A-1, Site Location Plan. See Appendix A, Exhibit A-2, Boring Location Plan. A traffic bridge founded on drilled footings. Assumed to be within approximately on to two feet of existing grade. AASHTO HS-20 Loading Drilled, straight-shaft foundation system. Responsive Resourceful Reliable 1 Addendum Two # Page 6 of 27

7 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A Site Description Item Site location Existing conditions Current ground cover Existing topography Description The areas of the proposed bridge is located southwest of the existing Thompson Creek Waste Water Treatment Plant, near the GPS coordinate of 30º N, 96º W in Brazos County Texas. The site is currently has an overhead transmission line, with the right of way cleared. The area outside of the right away is heavily wooded. The creek was observed to have a depth of about 30 feet Cultivated and native grasses, scattered trees, and dense underbrush. The topography appears to be sloping toward the creek. 3.0 SUBSURFACE CONDITIONS 3.1 Geology Geologically, the site is mapped as the Yegua formation of Eocene geologic age. The formation consists of clay, quartz sand and lignite. The upper part is mostly clay; the lower part is mostly sand. The clay is silty, lignitic and contains various shades of gray and brown. The sand is fine-grained, silty and light gray. The Yegua Formation extends 600 to 1,000 feet below the surface. 3.2 Typical Profile Based on the results of the boring, subsurface conditions on the project site can be generalized as follows: Stratum Approximate Depth to Bottom of Stratum (feet) 1 23 to 35 feet Material Description Fat clay with varying amounts of sand Consistency/Density Stiff to very stiff 2 33 feet (Boring B-1) Sandy lean clay Stiff to very stiff 3 40 feet (Boring B-1) Sandy fat clay Stiff to very stiff 4 45 to 60 feet Clayey and silty sand Medium dense to dense 5 60 feet (Boring B-2) Sandy elastic silt Loose to dense Responsive Resourceful Reliable 2 Addendum Two # Page 7 of 27

8 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A Stratum Continued from Page 2. 6 Approximate Depth to Bottom of Stratum (feet) Undetermined: Boring terminated within this stratum at the planned depth of approximately 70 feet Material Description Sandy silty clay Consistency/Density Very stiff The upper soil encountered in the borings consisted of fat and lean clays with varying amounts of sand, underlain by silty sands, clayey sands, sandy elastic silts, and sandy silty clays. Conditions encountered at the boring location are indicated on the individual boring log. Stratification boundaries on the boring log represent the approximate location of changes in soil types; in situ, the transition between materials may be gradual. Details for the boring can be found on the boring log in Appendix A of this report. 3.3 Groundwater Borings were advanced using dry drilling techniques to their termination depths. Groundwater was initially observed in borings B-1 and B-2 during dry drilling operations. Details for each boring can be found on the Boring Logs in Appendix A of this report. Summary of Short-Term Groundwater Information Boring No. Approximate Boring Depth 2 (feet) Approximate Groundwater Depth (feet) 2 While Drilling at 15 minutes B ½ 3 B ½ Groundwater measurements obtained on March 29, 2014 and April 2, Below existing grade at the time of our field activities. End of Borings water measurement. These groundwater measurements are considered short-term, since the borings were open for a short time period. On a long-term basis, groundwater may be present at shallower depths. Additionally, groundwater will fluctuate seasonally with climatic changes and should be evaluated at the time of construction. Responsive Resourceful Reliable 3 Addendum Two # Page 8 of 27

9 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION The following recommendations are based upon the data obtained in our field and laboratory programs, project information provided to us, and on our experience with similar subsurface and site conditions. 4.1 Geotechnical Considerations Construction operations may encounter difficulties due to wet and/or soft surface soils becoming a general hindrance to equipment, especially following periods of wet weather. If the subgrade cannot be adequately compacted to the minimum densities as described previously, one of the following measures will be required: 1) removal and replacement with select fill, 2) chemical treatment of the soil to dry and improve the stability of the subgrade, or 3) drying by natural means if the schedule allows. Based on our experience with similar soils in this area, chemical treatment is the most efficient and effective method to increase the supporting value of wet and weak subgrade. Terracon should be contacted for additional recommendations if chemical treatment is planned due to soft and wet subgrade. 4.2 Foundation Systems We understand that the proposed bridge is planned to be supported on a drilled, straight-shaft foundation system. Based on the subsurface conditions observed during our field and laboratory programs, this type of foundation system may be utilized to support the proposed building addition planned at this site, provided the subgrade is properly prepared as described in this report. Recommendations for this type of foundation system are provided in the following sections, along with other geotechnical considerations for this project Design Recommendations Drilled, Straight-Shaft Foundations Allowable skin friction and end bearing values for drilled, straight-shaft piers are presented in the following table. These design parameters were computed based on a generalized soil profile and engineering properties of the subsurface soils observed within the depths explored at this site. Responsive Resourceful Reliable 4 Addendum Two # Page 9 of 27

10 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A Depth Below Existing Grade 1 Design Parameters for Drilled Straight-Shaft Piers Net Allowable End Bearing Pressure 2 Allowable Side Friction 3 Allowable Passive Pressure 3 (feet) (psf) (psf) (psf) Disregard Capacity , , , , , ,000 Grade at the time of our field program. The net allowable end bearing pressure refers to the pressure at the foundation bearing level in excess of the surrounding overburden pressure. A minimum penetration of 2 feet or one-half a shaft diameter, whichever is greater, into the desired bearing strata should be achieved with a minimum of 4 feet of the selected bearing stratum beneath the shaft tip to use the recommended allowable end bearing pressure. The allowable passive pressure and side friction are based on a rectangular pressure distribution. Disregard due to depth of the creek A minimum penetration of 2 feet into the desired bearing strata with a minimum of 4 feet of the selected bearing stratum below the bottom of the shaft is required to achieve the recommended allowable end bearing values provided in the above table. Design of drilled, straight-shafts should also include an evaluation of the structural capacity of the foundation element which may limit the allowable capacity. There are numerous factors which contribute to the behavior of groups subjected to axial load. Several of these factors are foundation type, size and length, spacing, overall group size, loading conditions, installation procedures and soil type and strength. We recommend a minimum spacing of three diameters, center-to-center, for shafts placed in groups beneath square or rectangular caps. Closer spacing than three diameters in groups could result in increased group settlement and a reduction of load-carrying capacity of individual foundation elements. Settlement of a single, isolated shaft will depend on the elastic properties of the foundation, the applied load, and the interaction of the soil and foundation. Settlement is anticipated to be primarily elastic and will occur relatively soon as load is applied. Significant consolidation settlement due to applied load is not anticipated for the allowable capacities. Our experience indicates that a single, isolated foundation loaded to about one-half of its ultimate capacity will result in settlements of less than one inch. Groups generally undergo more settlement than single, isolated foundation elements for the same applied load. Based on the above recommended spacing, we anticipate that settlement of a group will be on the order of one inch under working loads with differential settlement between foundations to be one-half inch or less. Responsive Resourceful Reliable 5 Addendum Two # Page 10 of 27

11 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A The drilled, straight-shaft foundations will provide resistance to lateral loads through the passive earth pressure acting on the side of the foundation. A detailed lateral load analysis of the proposed drilled, straight-shaft piers was beyond the scope of this project. If requested, a detailed lateral load analysis of the proposed drilled, straight-shaft foundations can be performed by Terracon. Lateral loads should not exceed the structural capacity of the individual drilled, straight-shaft. Drilled, straight-shaft foundations will provide resistance to structural uplift loads through the mobilization of the skin friction acting at the interface of the shaft sidewall and the adjacent soils. The allowable skin friction values provided in the previous table may be used to calculate the uplift resistance for the shafts Construction Considerations Drilled, Straight-Shaft Foundations The drilling contractor should be experienced in the subsurface conditions observed at the site, and the excavations should be performed with equipment capable of providing a clean bearing area. The drilled straight-shaft foundation should be installed in general accordance with the procedures presented in "Drilled Shafts: Construction Procedures and Design Methods," by Reese, L. C. and O Neill, M. W., FHA Publication No. FHWA-IF , 1999 and "Standard Specification for the Construction of Drilled Piers", ACI Publication No , The successful completion of the drilled straight-shafts will depend to a large extent on the suitability of the equipment and the operator's skills. The operation sequence should be scheduled so that the shaft excavation can be completed, reinforcing steel placed, and the concrete poured in a continuous, rapid, and orderly manner to minimize the time the excavation is open. Concrete should be placed as soon as practical and in all instances should be placed within the same day in order to use the side friction values recommended in this report. Groundwater was observed at borings B-1 and B-2 during dry drilling at depths that varied from about 41½ to 42½ feet below existing grade. These groundwater measurements are considered short-term, since the borings were open for a short time period. Additionally, groundwater will fluctuate seasonally with climatic changes and should be evaluated at the time of construction. Based on the subsurface conditions observed, the installation of drilled straight-shafts will likely require the use of the Slurry Displacement Method and/or temporary steel casing. The use of the Slurry Displacement Method and/or temporary casing will likely be required below depths of approximately 10 feet due to the presence of sand soils below these depths. If drilled shaft installation is attempted without utilizing Slurry Displacement Method or temporary casing, zones of sloughing soils and/or groundwater inflow may occur during construction. Therefore, we recommend that provisions be incorporated into the plans and specifications to utilize slurry or casing to control sloughing and/or groundwater seepage during shaft construction. The need for casing or slurry will depend on the depth of the drilled shaft and the groundwater conditions at the time of construction. If casing is used and seepage persists, the water Responsive Resourceful Reliable 6 Addendum Two # Page 11 of 27

12 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A accumulating in the foundation excavation should be pumped out. The condition of the bearing surface should be evaluated immediately prior to placing concrete, if casing is used in lieu of slurry. If groundwater inflow is too severe to be controlled by the use of casing and pumping or significant sloughing of the sidewalls occurs, the slurry method of construction should be utilized to complete the foundation installation. Where casing is used, removal of the casing should be performed with extreme care and under proper supervision to minimize mixing of the surrounding soil and water with the fresh concrete. Rapid withdrawal of the casing may develop a suction that could cause the soil and water to flow into the excavation. An insufficient head of concrete in the casing during withdrawal could also allow the water to intrude into the wet concrete. Under no circumstances should loose soil be placed in the annulus between the casing and the drilled shaft sidewalls. The casing must be removed in order to utilize the skin friction values previously provided. During slurry displacement, the foundation excavation is filled with a slurry mixture. The level of slurry should be maintained above the groundwater level to maintain a positive head in the foundation excavation. Therefore, the slurry tends to seep out of the excavation, rather than the groundwater seeping into the open excavation. The slurry must be maintained in the foundation excavation until design termination depth is achieved and should be removed only as concreting proceeds. The properties of the slurry including the density, viscosity, and ph must be carefully controlled and should be in accordance with Item 416 of Texas Department of Transportation (TXDOT) Standard Specifications for Construction of Highways, Streets, and Bridges. Slurry left in place for long periods of time will build up on the sides of the shaft causing a reduction in skin friction. The following procedures and equipment are recommended for installation of drilled shafts by the Slurry Displacement Method: 1. The bottom of the drilled straight-shaft should be cleaned as well as practical just prior to concreting to remove cuttings. 2. The concrete should be placed by means of a tremie with a one-way valve to prevent slurry from entering the pipe. The tremie should extend to the bottom of the drilled shaft to allow displacement of the slurry during concrete placement. 3. During concrete placement, the end of the tremie should remain several feet within the concrete mass to reduce the entrapment of slurry. A tremie embedment of 5 to 10 feet is generally considered acceptable. 4. The concrete should be relatively fluid to reduce the entrapment of slurry. We recommend that concrete with a slump of 6 to 8 inches be used. 5. The upper few feet of concrete should be expunged from the shaft excavation if found to be contaminated with slurry or soil. Responsive Resourceful Reliable 7 Addendum Two # Page 12 of 27

13 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A A surface casing may be required in addition to the slurry for shaft installation at this site if sloughing of near surface soils occurs. Where casing is used, removal of the casing should be performed with extreme care as previously discussed in this section. Production shaft installation should be closely monitored by a qualified technician experienced in drilled shaft installation techniques. At a minimum, the technician should observe shaft excavation, note any unusual installation occurrences, monitor slurry properties and/or casing installation and removal, monitor concrete placement and generally evaluate if shaft installation is being performed in accordance with project specifications Foundation Construction Monitoring The performance of the foundation system for the proposed structure will be highly dependent upon the quality of construction. Thus, we recommend that foundation installation be monitored full time by an experienced Terracon soil technician under the direction of our Geotechnical Engineer. We would be pleased to develop a plan for foundation installation monitoring to be incorporated in the overall quality control program. 5.0 GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction, and other earth-related construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, and bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. For any excavation construction activities at this site, all Occupational Safety and Health Administration (OSHA) guidelines and directives should be followed by the Contractor during Responsive Resourceful Reliable 8 Addendum Two # Page 13 of 27

14 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A construction to insure a safe working environment. In regards to worker safety, OSHA Safety and Health Standards require the protection of workers from excavation instability in trench situations. This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. Responsive Resourceful Reliable 9 Addendum Two # Page 14 of 27

15 APPENDIX A FIELD EXPLORATION Addendum Two # Page 15 of 27

16 N SITE LOCATION N:\Projects\2014\A \A dwg : A-1-SiteLocationPlan 1,000' Project Mng. Drawn By: Checked By: Approved By: JDH JDH JDH AGR 0 500' SCALE IN FEET Project No. A Scale: AS SHOWN File No: A Date: ,000' DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES Consulting Engineers & Scientists Addendum Two # Page 16 of Imperial Loop College Station, Texas PH. (979) FAX. (979) SITE LOCATION PLAN Exhibit Proposed Thompson Creek Bridge Brazos County, Texas A-1

17 N B-1 N:\Projects\2014\A \A dwg : A-2BoringLocationPlan B-2 400' 0 200' 400' SCALE IN FEET Project Mng. DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES Project No. JDH A BORING LOCATION PLAN Exhibit Proposed Thompson Creek Bridge Brazos County, Texas A-2 Scale: Drawn By: AS SHOWN JDH Checked By: File No: JDH Approved By: A Date: AGR Consulting Engineers & Scientists Addendum Two # Page 17 of Imperial Loop College Station, Texas PH. (979) FAX. (979)

18 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A Field Exploration Description Subsurface conditions were evaluated by drilling two test borings, designated B-1 and B-2, to depths of approximately 70 feet below existing grade within the proposed bridge area The borings were drilled using ATV-mounted drilling equipment at the approximate locations shown on the Boring Location Plan, Exhibit A-2 of Appendix A. The boring depths were measured from the existing ground surface at the time of our field activities. At the completion of our field activities, the borings were backfilled with soil cuttings. The Boring Logs, presenting the subsurface soil descriptions, type of sampling used, and additional field data, are presented on Exhibits A-4 and A-5 of Appendix A. The General Notes, which defines the terms used on the logs, are presented on Exhibit C-1 of Appendix C. The Unified Soil Classification System is presented on Exhibit C-2 of Appendix C. Cohesive soil samples were generally recovered using open-tube samplers. Pocket penetrometer tests were performed on samples of cohesive soils to serve as a general measure of consistency. Granular soils and soils for which good quality open-tube samples could not be recovered were sampled by means of the Standard Penetration Test (SPT). This test consists of measuring the number of blows (N) required for a 140-pound hammer free falling 30 inches to drive a standard split-spoon sampler 12 inches into the subsurface material after being seated six inches. This blow count or SPT N-value is used to evaluate the stratum. A CME automatic SPT hammer was used in advancing the split-barrel sampler at the borings. A greater efficiency is typically achieved with the automatic hammer compared to the conventional safety hammer operated with a cathead and rope. Published correlations between the SPT N-values and soil properties are based on the lower efficiency cathead and rope method. The higher efficiency of an automatic SPT hammer affects the SPT N-value by increasing the penetration per hammer blow over what would be obtained using the cathead and rope method. Samples were removed from samplers in the field, visually classified, and appropriately sealed in sample containers to preserve their in-situ moisture contents. Samples were then transported to our laboratory in College Station, Texas. Samples not tested in the laboratory will be stored for a period of 30 days subsequent to submittal of this report and will be discarded after this period, unless we are notified otherwise. Addendum Two # Page 18 of 27 Exhibit A-3

19 PROJECT: Proposed Thompson Creek Bridge SITE: Brazos County, Texas BORING LOG NO. B-1 Bryan Texas Utlities CLIENT: Bryan, Texas Page 1 of 2 GRAPHIC LOG LOCATION See Exhibit A-2 DEPTH SANDY FAT CLAY (CH), light tan, stiff to very stiff DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS N=9 STRENGTH TEST TEST TYPE COMPRESSIVE STRENGTH (tsf) STRAIN (%) WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES HP=1½ 6.0 FAT CLAY (CH), dark tan and black, stiff to very stiff 5 HP=4½ HP=4½ HP=4 HP= HP=4½ 20 HP=4½ THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL A GINT.GPJ 23.0 SANDY LEAN CLAY (CL), dark gray, stiff to very stiff CLAYEY SAND (SC), dark gray, medium dense to dense 50.0 SANDY FAT CLAY (CH), dark gray and dark tan, stiff to very stiff Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: Dry augered to the termination depth. Abandonment Method: Borings backfilled with soil cuttings upon completion. WATER LEVEL OBSERVATIONS EOD See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. HP=4½ HP=2 HP=3 HP=3 HP=2½ HP=½ Hammer Type: Automatic Notes: Boring Started: 3/29/2014 Drill Rig: DR Imperial Loop College Station, Texas Project No.: A Addendum Two # Page 19 of Boring Completed: 3/29/2014 Driller: Roger Exhibit: A-4

20 PROJECT: Proposed Thompson Creek Bridge SITE: Brazos County, Texas BORING LOG NO. B-1 Bryan Texas Utlities CLIENT: Bryan, Texas Page 2 of 2 GRAPHIC LOG LOCATION See Exhibit A-2 DEPTH SILTY SAND (SM), dark gray, medium dense to dense DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS STRENGTH TEST TEST TYPE COMPRESSIVE STRENGTH (tsf) STRAIN (%) WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES 55 HP= SANDY SILTY CLAY (CL-ML), dark gray, very stiff 60 HP= N= Boring Terminated at 70 Feet N= THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL A GINT.GPJ Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: Dry augered to the termination depth. Abandonment Method: Borings backfilled with soil cuttings upon completion. WATER LEVEL OBSERVATIONS EOD See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. Hammer Type: Automatic Notes: Boring Started: 3/29/2014 Drill Rig: DR Imperial Loop College Station, Texas Project No.: A Addendum Two # Page 20 of 27 Boring Completed: 3/29/2014 Driller: Roger Exhibit: A-4

21 PROJECT: Proposed Thompson Creek Bridge SITE: Brazos County, Texas BORING LOG NO. B-2 Bryan Texas Utlities CLIENT: Bryan, Texas Page 1 of 2 GRAPHIC LOG LOCATION See Exhibit A-2 DEPTH SANDY FAT CLAY (CH), reddish brown and light tan, stiff to very stiff DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS HP=1 HP=2 STRENGTH TEST TEST TYPE COMPRESSIVE STRENGTH (tsf) STRAIN (%) WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES 6.0 FAT CLAY (CH), dark tan and black, stiff to very stiff 5 HP=4½ HP=4½ HP=4 HP= HP=3½ HP=4 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL A GINT.GPJ 23.0 SANDY FAT CLAY (CH), dark gray and dark tan, stiff to very stiff 35.0 CLAYEY SAND (SC), dark gray, medium dense to dense 45.0 SANDY ELASTIC SILT (MH), dark gray, loose to dense Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: Dry augered to a depth of 45 feet, wet rotary thereafter. Abandonment Method: Borings backfilled with soil cuttings upon completion. WATER LEVEL OBSERVATIONS WD at 5 minutes at 15 minutes See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. HP=3½ HP=3½ HP=2½ HP=2 HP=2½ Hammer Type: Automatic Notes: Boring Started: 3/28/2014 Drill Rig: D50 TRACK 6198 Imperial Loop College Station, Texas Project No.: A Addendum Two # Page 21 of Boring Completed: 3/28/2014 Driller: Roger Exhibit: A-5

22 PROJECT: Proposed Thompson Creek Bridge SITE: Brazos County, Texas BORING LOG NO. B-2 Bryan Texas Utlities CLIENT: Bryan, Texas Page 2 of 2 GRAPHIC LOG LOCATION See Exhibit A-2 DEPTH SANDY ELASTIC SILT (MH), dark gray, loose to dense (continued) DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS N=4 STRENGTH TEST TEST TYPE COMPRESSIVE STRENGTH (tsf) STRAIN (%) WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES N= SANDY SILTY CLAY (CL-ML), dark gray, very stiff N= N= Boring Terminated at 70 Feet N=36 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL A GINT.GPJ Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: Dry augered to a depth of 45 feet, wet rotary thereafter. Abandonment Method: Borings backfilled with soil cuttings upon completion. WATER LEVEL OBSERVATIONS WD at 5 minutes at 15 minutes See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. Hammer Type: Automatic Notes: Boring Started: 3/28/2014 Drill Rig: D50 TRACK 6198 Imperial Loop College Station, Texas Project No.: A Addendum Two # Page 22 of 27 Boring Completed: 3/28/2014 Driller: Roger Exhibit: A-5

23 APPENDIX B LABORATORY TESTING Addendum Two # Page 23 of 27

24 Geotechnical Engineering Report Propose Thompson Creek Bridge Brazos County, Texas April 15, 2014 Terracon Project No. A Laboratory Testing Soil samples were tested in the laboratory to measure their dry unit weight and natural water content. Unconfined compression tests were performed on selected samples and a calibrated hand penetrometer was used to estimate the approximate unconfined compressive strength of some cohesive samples. The calibrated hand penetrometer has been correlated with unconfined compression tests and provides a better estimate of soil consistency than visual examination alone. Selected samples were also classified using the results of Atterberg Limits and grain size analysis testing. The test results are provided on the Boring Logs included in Appendix A and presented in 3.2 Typical Profile section of this report. Descriptive classifications of the soils indicated on the Boring Logs are in general accordance with the enclosed General Notes and the Unified Soil Classification System. Also shown are estimated Unified Soil Classification Symbols. A brief description of this classification system is attached to this report. Classification of the soil samples was generally determined by visual manual procedures. Addendum Two # Page 24 of 27 Exhibit B-1

25 APPENDIX C SUPPORTING DOCUMENTS Addendum Two # Page 25 of 27

26 GENERAL NOTES DRILLING & SAMPLING SYMBOLS: SS: Split Spoon / 8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube 2 O.D., 3" O.D., unless otherwise noted PA: Power Auger (Solid Stem) RS: Ring Sampler " I.D., 3" O.D., unless otherwise noted HA: Hand Auger DB: Diamond Bit Coring - 4", N, B RB: Rock Bit BS: Bulk Sample or Auger Sample WB Wash Boring or Mud Rotary The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the Standard Penetration or N-value. WATER LEVEL MEASUREMENT SYMBOLS: WL: Water Level WS: While Sampling BCR: Before Casing Removal WCI: Wet Cave in WD: While Drilling ACR: After Casing Removal DCI: Dry Cave in AB: After Boring N/E: Not Encountered Water levels indicated on the Boring Logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations. DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS Unconfined Compressive Standard Penetration or N-value (SS) Consistency Standard Penetration or N-value (SS) Relative Density Strength, Qu, psf Blows/Ft. Blows/Ft. < Very Soft 0 3 Very Loose 500 1, Soft 4 9 Loose 1,000 2, Medium Stiff Medium Dense 2,000 4, Stiff Dense 4,000 8, Very Stiff > 50 Very Dense 8,000+ > 30 Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Term(s) of other constituents Percent of Dry Weight GRAIN SIZE TERMINOLOGY Major Component Particle Size of Sample Trace < 15 Boulders Over 12 in. (300mm) With Cobbles 12 in. to 3 in. (300mm to 75mm) Modifier 30 Gravel 3 in. to #4 sieve (75mm to 4.75mm) Sand #4 to #200 sieve (4.75 to 0.075mm) Silt or Clay Passing #200 Sieve (0.075mm) RELATIVE PROPORTIONS OF FINES Descriptive Term(s) of other constituents Percent of Dry Weight PLASTICITY DESCRIPTION Plasticity Term Index Trace < 5 Non-plastic 0 With 5 12 Low 1-10 Modifier > 12 Medium High > 30 Addendum Two # Page 26 of 27 Exhibit C-1

27 UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Coarse Grained Soils: More than 50% retained on No. 200 sieve Fine-Grained Soils: 50% or more passes the No. 200 sieve Gravels: More than 50% of coarse fraction retained on No. 4 sieve Sands: 50% or more of coarse fraction passes No. 4 sieve Silts and Clays: Liquid limit less than 50 Silts and Clays: Liquid limit 50 or more Group Symbol Soil Classification Group Name B Clean Gravels: Cu 4 and 1 Cc 3 E GW Well-graded gravel F Less than 5% fines C Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F Gravels with Fines: Fines classify as ML or MH GM Silty gravel F,G, H More than 12% fines C Fines classify as CL or CH GC Clayey gravel F,G,H Clean Sands: Cu 6 and 1 Cc 3 E SW Well-graded sand I Less than 5% fines D Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I Sands with Fines: Fines classify as ML or MH SM Silty sand G,H,I More than 12% fines D Fines Classify as CL or CH SC Clayey sand G,H,I Inorganic: Organic: Inorganic: Organic: PI 7 and plots on or above A line J CL Lean clay K,L,M PI 4 or plots below A line J ML Silt K,L,M Liquid limit - oven dried Organic clay K,L,M,N 0.75 OL Liquid limit - not dried Organic silt K,L,M,O PI plots on or above A line CH Fat clay K,L,M PI plots below A line MH Elastic Silt K,L,M Liquid limit - oven dried Liquid limit - not dried Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat 0.75 OH Organic clay K,L,M,P Organic silt K,L,M,Q A Based on the material passing the 3-in. (75-mm) sieve B If field sample contained cobbles or boulders, or both, add with cobbles or boulders, or both to group name. C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay E Cu = D 60/D 10 Cc = D (D ) 2 x D 60 F If soil contains 15% sand, add with sand to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. H If fines are organic, add with organic fines to group name. I If soil contains 15% gravel, add with gravel to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 15 to 29% plus No. 200, add with sand or with gravel, whichever is predominant. L If soil contains 30% plus No. 200 predominantly sand, add sandy to group name. M If soil contains 30% plus No. 200, predominantly gravel, add gravelly to group name. N PI 4 and plots on or above A line. O PI 4 or plots below A line. P PI plots on or above A line. Q PI plots below A line. Addendum Two # Page 27 of 27 Exhibit C-2