I. Request for Proposal (RFP) submission REMAINS as June 26, 2017 at 5:00 PM (per preceding Addendum #1).

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2 RFP Addendum No. 2 Attention of all Teams is directed to the following addendum to this RFP 15 17: I. Request for Proposal (RFP) submission REMAINS as June 26, 2017 at 5:00 PM (per preceding Addendum #1). I. RFP Questions and Answers 1.01 QUESTION: What are TXDOT standard work hours in El Paso and does EPWU expect Contractor to work only 9:00 AM to 4:00 PM in its construction schedule? 1.01 ANSWER: Work within TXDOT Right Of Way surface, particularly traffic control operations are limited to 9:00 AM to 4:00 PM QUESTION: What is BNSF s Railroad Flagman rate? 1.02 ANSWER: Currently, BNSF flagman rate is usually quoted between $800 and $1,600 per day, rate is dependent on timeframe they are required. As with all other resources, Contractor should evaluate escalation costs and make appropriate adjustments necessary to hold pricing for the duration of the project QUESTION: Specification section B 12 The maximum allowable over cut shall not be greater than ¾ inch larger in radius than the outside of the jacked pipe You have to overcut to reduce the friction, give room to inject the bentonite lubrication and steer the shield. Is a variance on this acceptable? 1.03 ANSWER: The 30% Design documents supplied are for information only and their interpretation and applicability are the responsibility of the selected Team s Engineer of Record. A complete design packet and its associated specifications will need to be developed by the Team s Engineer of Record QUESTION: Specification section SHAFT EXCAVATION 1.08 A The Contractor will have the sole responsibility for maintenance and protection of existing utilities, structures, and facilities within the zone of influence. The Owner has provided as builds for existing utilities in the work zone (Vol 4 of 4). Do these as builds represent all the existing utilities known to the Owner? Who will have the ultimate responsibility to identify what existing (and potential abandoned) utilities are located in the work zone, Owner or D B Contractor? 1.04 ANSWER: The Design Built Contractor will be responsible for identifying existing utilities QUESTION: Specification section TUNNEL EXCAVATION BY MICROTUNNEL BORING MACHINE 2.01 EQUIPMENT (B) The MTBM shall be a closed full face machine designed and build or rebuilt conditions on this project by a recognized MTBM manufacturer with at least 5 years experience in the design and manufacture of MTBMs of this type. The manufacturer must 2

3 RFP Addendum No. 2 still be in the business of designing and manufacturing MTBMs. Please confirm this is your intent. The US market contains a large number of MTBMs from defunct manufacturers that have the capabilities specified in this spec section as well as the capability to be rebuilt and retrofitted with replacement parts supplied from active manufacturers ANSWER: The 30% Design documents supplied are for information only and their interpretation and applicability are the responsibility of the selected Team s Engineer of Record. Means & methods within the confines of the BNSF & TxDOT permits are the Design Build Team s responsibility QUESTION: 2.01 B (3) The machine shall have a data logger that records all the above at a min of 10 min intervals to a portable digital storage device in a format that can be imported into Microsoft Excel. Would the Owner accept a hard copy record with the required data or must the data be in digital format? 1.06 ANSWER: Hardcopy records will present an unnecessary burden for the Owner s quality assurance team evaluation. The burden of deriving a verifiable digital data file from the data logger s hardcopy records shall reside with the Design Build QUESTION: Specification TUNNEL EXCAVATION 1.04 E, Tolerances to line and grade shall be as follows: H 3 inches, V 3 inches. Should tolerances for the MTBM Spec (1 inch H and V) be equal to those of other methods? 1.07 ANSWER: The 30% Design documents supplied are for information only and their interpretation and applicability are the responsibility of the selected Team s Engineer of Record. Means & methods within the confines of the BNSF & TxDOT permits are the Design Build Team s responsibility. II. The Geotechnical Baseline Report (GBR) is a Draft Document upon which the Design Build Team can rely for bid purposes. The Design Build Team shall build upon said document for the completion of their own Design. It is the responsibility of the Design Build Team to acquire their own information, analyze and conclude the existing field conditions that are present to determine what will be required for a successful project. III. Revised Geotechnical Baseline Report Canal Water Treatment Plant 48 Inch Discharge Transmission Main, June 21,

4 RFP Addendum No. 2 IV. Revised Specification Sections that have been tracked: Tunneling Definitions Shaft Excavation Micro Tunneling Has been re named to PIPE JACKING (Included either microtunneling or shield with cutter wheel Tunnel Excavation This section is deleted Installation of Pipe in Tunnel Instrumentation and Monitoring Low Density Cellular Concrete Has been re named to LOW STRENGTH CONTROLLED GROUT V. Add the following notes to RFP VOLUME 3 PLAN DRAWING SHEET C 4 MONITORING INSTRUMENTATION PLAN: a. MONITORING ARRAY OF SURFACE SURVEY POINTS IS A SUGGESTED ARRANGEMENT OF INSTRUMENTATION IF DAILY SURVEY OF THE POINTS IS TO BE PERFORMED. b. MA LOCATIONS SHOWN ON SCHEDULE IS SUGGESTED LOCATIONS. FINAL LOCATIONS ARE TO BE DETERMINED BY THE CONTRACTOR S ENGINEER OF RECORD. c. IF AN AUTOMATED SYSTEM OF MONITORING PRISM POINTS IS SELECTED BY THE D/B TEAM THESE ARRAYS SHOULD BE PLACED ON TIES AT EACH RAIL TRACK CROSSING. 4

5 Revised Geotechnical Baseline Report Canal Water Treatment Plant 48 Inch Discharge Transmission Main El Paso Water El Paso, Texas June 21, 2017

6 Section 1 Introduction 1.1 Introduction This Geotechnical Baseline Report (GBR) has been prepared for the trenchless portions of the Canal Water Treatment Plant 48-Inch Discharge Transmission Main Project, in the city of El Paso, Texas. This project was designed by CDM Smith originally as a Design/Bid/Build and now revised to a Design/Build contract format. As such this GBR is now considered a Geotechnical Baseline Report Bid (GBR-B). The term Engineer and CDM Smith are equivalent in this report. ForThere will be an opportunity for the selected Design/Build Team (D/BT) to obtain additional subsurface information and if these new data indicate a change in conditions the D/BT can prepare a supplemental GBR. This revised report once accepted by the Owner will serve as the contract baseline report for construction, and will be identified as the GBR-C. This project involves the construction of three vertical launch shafts and two tunneled excavations from shaft to shaft as shown on the Contract Drawings. 1.2 Purpose and Organization of Geotechnical Reports The geotechnical Contract Documents for this project are comprised of Contract Drawings, Contract Specifications, the Geotechnical Data Report (GDR) and the Geotechnical Baseline Report (GBR-B). The GDR provides a description of the procedures and presents the results of the field exploration program, geotechnical field and laboratory testing conducted for this project and the regional and site specific geologic setting and site conditions. The purpose of the GBR-B is (1) to set clear, realistic baselines for geotechnical parameters on construction of the proposed rock tunnel, (2) to provide a uniform basis for ground conditions to be used in bidding, and (3) to provide a basis for resolution of any claims of Differing Site Conditions (DSC) if there is acceptance to the contents of the report. If there are changes by the D/BT that are accepted by the Owner, that document, GBR-C will supersede this GBR-B. Changes from the baselines established in GBR will be handled in accordance with provisions stated in the Contract. 1.3 Hierarchy in Relation to the Contract Documents This GBR and the GDR are part of the Contract Documents for the Raw Water Intake Tunnel. The order of precedence of the contract documents is Contract Specifications Contract Drawings Geotechnical Baseline Report-B Geotechnical Data Report 1-1

7 Section 1 Introduction This GBR does not present the minimum required design and standards of construction. Those are contained in the Contract Drawings and Contract Specifications. Nothing in this GBR-B should be construed as amending the Contract Drawings and Contract Specifications or relaxing the standards of construction or the Contractor s responsibilities according to the Contract Drawings and Contract Specifications. 1.4 Organization of GBR-B An outline of this GBR is presented below: Section 1 Introduction provides the project background, describes the purpose and scope, and limitations of this report and provides a project description. Section 2 Geologic Settings describes the different rock formations encountered, and presents the contract interpretation of subsurface soil, rock and groundwater conditions that underlie the project. Section 3 Ground Characterization describes relevant local project experience and baseline geotechnical parameters for construction of the tunnel and shafts per American Society of Civil Engineers (ASCE) suggested guidelines for geotechnical baseline reports for construction (2007 edition). Section 4 Construction Considerations discusses construction sequencing, ground conditions to be anticipated by the Contractor, excavation methods, rationale for requirements contained in the specifications that prescribe specific means and methods, tunnel support requirements, special construction consideration, groundwater conditions and rationale for baseline estimates of groundwater inflows to be encountered during construction, and ground improvement techniques. Section 5 References 1.5 Warranty This baseline represents a contractual definition of what ground conditions are assumed to be encountered with respect to the Differing Site Conditions (DSC) clause. The provisions in this baseline are not a warranty that the baseline conditions will in fact, be encountered. This Report is not a warranty; rather, it is a promise by the Owner, El Paso Water Utilities, that baseline conditions presented in this report or those conditions in the GBR-C that supersede this GBR-B will be used when interpreting the DSC clause. The baseline values established herein were developed based on geotechnical information and data gathered through exploration borings, laboratory and field tests, and other relevant factors, such as local construction experience. The judgment applied in the interpolations and extrapolations of this information reflects the view of the Engineer and Owner in establishing baselines. Therefore, the geotechnical baseline conditions contained herein are not necessarily geotechnical fact; the actual conditions encountered are expected to be representative of the range of values, but the locations at which they are encountered will vary. 1-2

8 Section 1 Introduction It has been assumed that the Contractor will employ construction methods and industry-accepted levels of workmanship, conforming to the Specifications, Drawings, and as presented in this document. Information and baselines are stated once within this report. 1.6 Project Description The overall project will include the installation of new 48-inch pipeline for two contiguous tunnel crossings planned for the Canal Water Treatment Plant (WTP). One crossing will be approximately 570 linear feet and will pass underneath the Burlington Northern Santa Fe (BNSF) rail yard just west of the existing Canal WTP. The second crossing will be about 315 linear feet and will pass underneath Paisano Drive near the intersection of W. San Antonio Avenue. Three shafts will be constructed to accommodate the tunneling operations. The trenchless section of the project will be supported by a 72-inch steel casing as required by BNSF Utility Accommodation Policy (2011) which states the nominal diameter of steel casing pipe should be 12- to 24-inches greater than the nominal diameter of the carrier pipe. This GBR-B pertains to the tunnel/trenchless portions and the associated shafts of the project only. 1.7 Project Datum The horizontal project datum is the North American Datum of 1983 (NAD 1983), in feet. The elevations (El.) noted herein are in feet and referenced to the North American Vertical Datum of 1988 (NAVD 88). 1-3

9 Section 2 Geological Setting 2.1 Geology General This section describes the project setting in terms of physiography and land use, regional geology, geologic setting, and structural geology. Physiography and Land Use The proposed Canal WTP Tunnel will be constructed for the El Paso Water Utilities Canal Water Treatment Plant located in El Paso, Texas. The trenchless section of this project begins on WTP property west of the plant structures and to the south of the BNSF rail yard in flat undeveloped land. The tunnel alignment from approximately Sta 6+00 will head north underneath the BNSF rail yard to a shaft at the north of the rail yards, approximately Sta From that location the tunnel alignment will generally head to the east underneath Paisano Dr. to a shaft in the general location of Sta and will connect into an existing 48-inch line near the intersection of W. San Antonio Avenue and Anthony Street. The Canal WTP is bounded to the south by the Rio Grande River and a canal network managed by the US Bureau of Reclamation. The Rio Grande River in the vicinity of the project generally forms the border between the United States and Mexico. The GBR specifically focuses on the tunnel crossing with existing ground surface elevations along the alignment generally ranging from 3702 feet at the southwest end to 3709 feet at the northeast end. Based on existing ground surface elevations at the trenchless crossing and proposed flow line elevations, shaft and bore pit excavations will range in depth from approximately 18 to 25 feet. The existing ground surface at the South Shaft location (near boring B-1) consists of a relatively flat undeveloped area north of the canal with similar site conditions at the intermediate shaft north of the rail yard. The existing ground surface at the North Shaft location (near boring B-6) consists of developed property and paved roadways. Regional Geology Regionally, the proposed tunnel alignment is located on recent and ancestral floodplain deposits of the Rio Grande River within the Texas Basin and Range physiographic region. The region was controlled by ancient tensional forces forming the numerous elongated basins separated by mountain ranges giving the area its present-day geomorphology. The most prominent mountain range is the Franklin Mountains that extend from El Paso, Texas north into New Mexico. 2-1

10 Section 2 Sources of Geologic and Geotechnical Information and Geological Setting Geologic Setting The Geologic Map (Figure 2) indicates that the project is situated on floodplain deposits of the Rio Grande River and are mapped as Alluvium of Rio Grande floodplain (Qarg). The GDR indicates that the borings drilled for the trenchless portion of the alignment encountered floodplain deposits of the mapped Qarg unit. Fill Fill was encountered in borings B-2, B-3, B-4, and B-6. The Fill is most likely derived from the surrounding alluvial soils and dumped debris. It is described as heavily contaminated with coal and coal waste. It is described as brown silty sand with traces of yellow brick, slag and gravel. During the original of advancement of boring B-6, construction debris and an unidentified steel object was encountered from 2 to 7-foot of depth. The drilling operations were terminated and the location of boring B-6 was moved two feet north where the logged hole was completed. Alluvium of Rio Grande Floodplain (Qarg) Alluvium of Rio Grande floodplain (Qarg) deposits were encountered in all of the geotechnical borings drilled for the proposed tunnel. The Qarg is described in the geologic literature as having various quantities of sand, silt, mud, and gravel locally covered by undivided windblown sand. The Qarg consists mostly of loose to very dense sands with varying amounts of gravels, silts, and clays (SP, SP- SM, SM, and SC-SM). Distinct gravel layers or lenses were also noted (GP, GM, and GP-GM). Some lean clay (CL and CL-ML) lenses were also observed in borings B-2, B-3, and B-6. Consistency of the finegrained soils classify mostly as very stiff to hard. Structural Geology Regionally, the most dominant structural feature is the Franklin Mountains with a topographic relief up to 7,200 feet mean sea level (msl). El Paso flanks the mountains just to the south and east. The mountain range is bounded on the east by a distinct north trending Quaternary fault, the East Franklin Mountain fault, which crosses the El Paso and North Franklin Mountain Quadrangles. Further to the east are the Hueco Mountains which are separated from the Franklin Mountains by a large basin known as the Hueco Basin. Groundwater The project site is located within close proximity to the Rio Grande River, groundwater levels are highly influenced by the river levels. Groundwater was observed in boring B-6 at around elevation 3,680 feet msl (approximately 30 feet of depth). Downstream water demands will result in water releases that will have a dramatic effect on raising the depth of the water in the river. Because the river runs very low to dry the majority of the time flow in the river during a release results in 2-2

11 Section 2 Sources of Geologic and Geotechnical Information and Geological Setting groundwater flowing out of the river to the surrounding land rather than the more typical condition of groundwater flowing to a river. 2-3

12 Section 3 Ground Characterization 3.1 Introduction This section provides a summary of subsurface conditions based on the exploration data presented in the GDR. In addition, actual baseline parameters are set forth. A plan of the borings and a generalized Subsurface Profile is shown on Figures 3a and 3b. Boring logs are presented in the GDR. Representative index properties, water contents, liquid limits, plasticity indices, percentages of material passing the No. 200 sieve size, compressive strengths are either tabulated on boring logs or presented in tables and graphs in the GDR. Alluvium (Qarg) The floodplain deposits (Qarg) are described in the geologic literature as having various quantities of sand, silt, mud, and gravel locally covered by undivided windblown sand. At the Project site, the Qarg consists mostly of loose to very dense sands with varying amounts of gravels, silts, and clays (SP, SP- SM, SM, and SC-SM). Distinct gravel layers or lenses were also noted (GP, GM, and GP-GM). Some lean clay (CL and CL-ML) lenses were also observed in borings B-2, B-3, and B-6. Consistency of the finegrained soils typically classify as very stiff to hard. Table 3-1 summarizes the Alluvium fine-grained soils Silt & Clay CL w LL PL PI Shear, tsf Average Set And Table 3-2 summarizes the coarse-grained Alluvium soils by sand and gravel. Gravel - GM, GP and GP-GM D100 D60 D30 D10 %GRAV %SAND % SILT & CLAY N values Average ±14 Set Sand- SP and SP-SM Average Set Std Dev CI - 95% porosity,n% 20 to 25% 25 to 30% 3-1

13 Section 3 Ground Characterization Groundwater The river bed is dry most of the year. The river will contain water when there is a called for demand downstream. As stated in the geology section when there is flow in the river, water can be expected to flow out of the river as groundwater contrary to most cases where groundwater flow is to a river. This is due to the demand and release of impounded water. Groundwater was only encountered during drilling in boring B-6 at around elevation 3,680 feet msl. 3-2

14 Section 4 Construction Considerations 4.1 Shaft and Tunnel Soil Property Baseline Values The range of alluvium soil property parameter baseline properties of the soil are presented in Table 4-1 through 4-3. Table 4-1 presents the gradation baseline of the Alluvium sand and gravel strata. There is a limited quantity of gravel samples to develop a meaningful statistical description so only a baseline range is presented based on the limited data available. The index parameter values of the fine-grained, clay stratum in Table 4-2. There is limited quantity of test data to develop a meaningful statistical description of these parameters. A baseline range is presented based on the limited data. Baseline strength and consistency parameters of the Alluvium is presented in Tables 4-3 for the sand, gravel and clay. Table 4-1 Baseline Soil Gradation Properties Granular Soils Sand Gradation D 100 D 60 D 30 D 10 Average size Baseline size 21.5 to to to to 0.13 Gravel Gradation Baseline size 35 to 40 5 to 10.5 to to 0.3 Table 4-2 Baseline Soil Properties Fine-Grained Soils Clay Water Content LL PL Baseline Index Properties 15 to to to 20 Table 4-3 Baseline Soil Strength Properties SPT N value Porosity n% Unit Weight, pcf Ka, Ko and Kp Sand Average 28 27% Baseline 21 to to 30% , 0.5 and 3.2 Gravel Average 45 23% Baseline 30 to to 25% , 0.5 and 35 Clay Compressive, tsf Average to 2.2 Baseline 32 to h-2c, -, h+2c 4-1

15 Section 4 Design and Construction Considerations 4.2 Shaft Support There is expected to be three shafts for the construction of the tunnels. The Contractor has the option of using any one or two of the shafts as a jacking launch shaft. For discussion purposes to identify these shafts approximate locations are at: Sta 6+00, and The subsurface conditions at these shafts are summarized in Table 4-4. Table 4-4 Subsurface Soil Strata at Approximate Shaft Locations Soil Stratum Shaft 6+00 Shaft Shaft Fill 3 to 5 ft 6 to 8 ft 14 to 16 ft Clay 8 to 10 ft Not present Not present Sand (SP - SM) 3 to 5 ft 22 to 26 ft 24 to 30 ft Gravel (GP- GM) 16 to 20 ft 2 to 4 ft Not present Sand (SP-SM) > 20 ft 16 to 20 ft 26 to 30 ft Clay Not present above el 3670 > 14 ft >16 ft The Contractor is responsible for the installation of all initial support systems as specified and shown on the Drawings to provide for the safety of the excavation and to achieve and maintain stable ground conditions until the carrier pipe is installed. The type of initial support to be installed is based on the ground conditions presented in the preceding tables. The Contractor is responsible to develop a support of excavation to the depth required to install the tunnel by jacking the steel casing to line and grade so that the 48-inch carrier pipe can be installed to the line and grade shown on the Contract Drawings. The configuration of each shaft is the responsibility of the Contractor, including design of the thrust reaction block, any required internal bracing, surcharge loading due to stockpile of materials and/or construction equipment that will cause a lateral loading on the shaft support system and changes in groundwater due to either rain events or river flow releases. 4.3 Construction Considerations Shaft The anticipated ground conditions in terms of ground profile at each shaft location is presented in Table 4-3. The Contractor can anticipate that cobbles and boulders will be encountered in the GP-GM stratum. A total of three boulders, 1.5 cu ft volume/ boulder should be anticipated. Groundwater elevation due to either natural causes or river releases is baselined at Elev Tunnels The tunneling is primarily in the coarse-grained alluvium consisting of a mixed face of sand with a layer of gravel alluvium at the tunnel horizon for 90 to 95% of the total alignment. A mixed face of sand and clay layers can be anticipated for less than 5% of the total alignment. A full face of sand can be anticipated in less than 5% of the total alignment. Without any support, the tunnel roof is not stable and therefore a shield or MTBM is required. Without face support the sand can be expected to behave as a slow running material. The unbalanced load moving into the face is about 5 to 10 % of the effective vertical overburden stress at the face of the tunnel. To mitigate lost ground due to this unbalanced load will require either internal face support or ground modification by 4-2

16 Section 4 Design and Construction Considerations grouting. If grouting is the selected option the contractor should assume that injection of grout will require horizontal drilling from the shaft and/or tunnel face. When in the mixed face containing the gravel stratum, the contractor can anticipate encountering cobbles and boulders. A boulder is defined as a rock with minimum dimensions of 12-inches. Stoppage in tunnel advance to remove boulders or nested cobbles that are not removed on a routine basis should be anticipated. For bidding purpose, the contractor can anticipate a total of 75 boulders each in excess of 1.5 cu ft can be expected. The selection of the method of excavating the ground by either microtunneling or shield with cutter wheel is the responsibility of the contractor. In making this selection the contractor should take into account the ability to remove boulders from the face and the delay time associated with this activity versus the requirement to provide adequate face support at all time so that settlement due to boulder removal along with other tunneling activities does not exceed the action levels as specified in the contract documents. In general, the overburden soil above the tunnel is medium dense, with a baseline N value of 10 to 18 blows/ft. Because of this density, volume of the surface settlement trough due to ground loss at the tunnel face and along the tunnel length can be expected to be close to the volume of lost ground. When tunneling in the sand and clay mixed face the clay stratum is stable. However, the contractor should not anticipate a full face of clay to be encountered in the alignment. The clay stratum can be expected to have a high clogging potential due to stickiness. 4-3

17 RFP Addendum No. 2 III. Revised Specification Sections that have been tracked: Tunneling Definitions Shaft Excavation Micro Tunneling - Has been re-named to PIPE JACKING (Included either microtunneling or shield with cutter wheel Tunnel Excavation - This section is deleted Installation of Pipe in Tunnel Instrumentation and Monitoring Low Density Cellular Concrete - Has been re-named to LOW STRENGTH CONTROLLED GROUT IV. Add the following notes to RFP VOLUME 3 - PLAN DRAWING SHEET C-4 MONITORING INSTRUMENTATION PLAN: a. MONITORING ARRAY OF SURFACE SURVEY POINTS IS A SUGGESTED ARRANGEMENT OF INSTRUMENTATION IF DAILY SURVEY OF THE POINTS IS TO BE PERFORMED. b. MA LOCATIONS SHOWN ON SCHEDULE IS SUGGESTED LOCATIONS. FINAL LOCATIONS ARE TO BE DETERMINED BY THE CONTRACTOR S ENGINEER OF RECORD. c. IF AN AUTOMATED SYSTEM OF MONITORING PRISM POINTS IS SELECTED BY THE D/B TEAM THESE ARRAYS SHOULD BE PLACED ON TIES AT EACH RAIL TRACK CROSSING. 3

18 SECTION TUNNELING DEFINITIONS PART 1: GENERAL 1.01 TUNNELING DEFINITIONS A. ANNULUS: The region between the outside of the Pre-fabricated Pipe and the inside of the initial Supportjacked steel pipe casing. B. BASELINE: A definition of certain expected conditions during the work on the Project. The Geotechnical Baseline Report describes conditions that will be used as the basis for differing site conditions of the Work. C. CELLULAR CONCRETELow Strength Controlled Grout (LSCG): Lightweight, ccementitious material which contains stable air or gas cells uniformly distributed throughout the mixture, with compressive strength of 500 psi and is capable of being pumped over a minimum distance of 600 feet.an oven-dried unit weight of 75 pcf or less. D. CUT-OFF GROUTING: The injection of grout materials from the excavated tunnel, behind the tunnel or shaft sidewall to reduce water inflows or maintain the ground water elevation. E. DESIGN/ BUILD TEAM (D/B Team): Parties consisting of Contractor, Contractor s Engineer of Record and all subcontractors on the Contractor s payroll. F. ENGINEER - Unless noted otherwise, the engineer shall mean the Contractor s Engineer of record for the Design. E.G. EXCAVATION NEAT LINE: Theoretical line for excavation inside of which no ground shall protrude. The Contractor will not be paid for excavation outside the neat line without prior written authorization from the Owner. H. GEOTECHNICAL BASELINE REPORT BID (GBR-B); The purpose of the GBR-B is to present an interpretive summary of the results of geotechnical investigations completed for the proposed Canal Water Treatment Plant 48-Inch Discharge Transmission Main Project in El Paso, Texas. The report presents interpretive discussions represent the geotechnical baseline conditions that the Bidder is responsible to meet in development of the means and methods for construction and cost for the tunneling portion of this process for the bid stageis of design for the project as presented in the Contract Drawings and Specifications. It is also intended to establish baseline conditions with respect to subsurface ground conditions in and around the proposed construction horizon. The GBR-B, Contract Drawings and Specifications are intended to provide an interpretation of subsurface conditions and expected behavior of the ground during assist prospective bidders in evaluating requirements for excavating, shoring, dewatering, and tunneling activities necessary to accomplish the work. F. GEOTECHNICAL BASELINE REPORT CONSTRUCTION (GBR-C); This report is a supplement to the GBR-B, and is prepared by the Design/Build team based on new information developed by the D/B team as a result of addition explorations and factual data obtained by the D/B team. Information collected and used by the D/B team to develop this supplemental report Formatted: List Paragraph, Left, Indent: First line: 0" Formatted: List Paragraph, Left, Indent: First line: 0" Formatted: List Paragraph, Left, Indent: First line: 0" % Submittal

19 shall be provided to the Owner for review. The GBR-C shall be reviewed by the Owner s engineer prior to its acceptance by the Owner. The accepted version of the GBR-C shall be used as a basis for any change condition claim by the D/B Team. to assist the Contactor in planning the work and designing temporary facilities; and to assist the Engineer and Owner in reviewing and monitoring the Contractor s submittals and operation and evaluate the validity of differing site condition claims. I. H.J. GEOTECHNICAL DATA REPORT (GDR); the purpose of the GDR was to develop sufficient data to portray subsurface conditions along the tunnel alignment and at the tunnel access shaft. The scope of the investigation included a literature review of pertinent geologic and geotechnical information, exploratory drilling conducted along the tunnel alignment, groundwater level monitoring, and laboratory testing to aid in the classification of subsurface materials and the determination of engineering properties. Formatted: Indent: Left: 0.75", No bullets or numbering I.K. GROUND SUPPORT: 1) steel sets, with or without lagging or tunnel liner plates, installed individually or otherwise, to provide support for the excavated portion of the tunnel or shafts. 2) Steel casing, to provide support for the excavated portion of the tunnels. 3) Sheet piles, with or without additional wales that provides support to an excavated shaft. J.L. INITIAL SUPPORT: The structural or mechanical devices used to stabilize tjacked steel casing to provide ground support during pipe jacking method of tunneling until he tunnel opening long enough to install the carrier pipe is installed and the annular space final between the carrier pipe and steel casing is filled with LSCG. (permanent) support. As specified in Section 02440, Tunnel Ground Support. M. PIPE JACKING Method of tunneling that consists of advancing pipes by applying a thrust to the assembled pipe segments in the shaft. The method of faced support consist of either a microtunnel boring machine (MTBM) or open face shield with cutter wheel and additional support system to control face stability and loss of ground during tunneling. K.N. PRE-EXCAVATION GROUTING: The injection of grout materials through holes drilled in advance of tunnel face or shaft bottom to control water inflows, maintain ground water levels, and/or to stabilize the ground mass. L.O. SHIELD EXCAVATION: Excavation using a jacked shield with cutter wheel to protect the workers and to provide a safe area to excavate the face and to erect the ground support Additional ground support to control ground movement may be required with this method of pipe jacking. Formatted: List Paragraph, Left, Indent: First line: 0" Formatted: Indent: Left: 0" M.P. SPRINGLINE: In a horseshoe tunnel, springline are the points where the curved portion of the roof meets the vertical legs of the horseshoe. In a circular tunnel, the springlines is the straight line connected by pair of are the points at opposite ends of the horizontal centerline. N. TBM EXCAVATION: Excavation by full-face Tunnel Boring Machine (TBM) utilizing a rotating cutterhead, including mucking operation and supporting underground openings. Formatted: Indent: Left: 0.81", No bullets or numbering P.Q. TUNNEL ENGINEER: The Contractor s Tunnel Engineer may either be an individual or % Submittal

20 an engineering consulting firm. The Tunnel Engineer may either be a subcontractor or an employee of the Contractor. The Tunnel Engineer shall include an engineer who is a graduate civil, mining or geological engineer and is a Licensed Professional Engineer in the State of TexasUnited States. Q.R. WATER/CEMENT RATIO: The weight of water divided by the weight of cementitious material used in the grout mix. END OF SECTION % Submittal

21 SECTION SHAFT EXCAVATION PART 1: GENERAL 1.01 SCOPE OF WORK A. The work includes design, procurement, installation, and execution of shaft excavation and support for the shafts associated with the Canal Water Treatment Plant Tunnels. B. The work specified includescontractor S Engineer shall develop requirements for excavation and support of all shafts and any other excavations required for tunnel construction. Requirements shall include d Design, furnish, install, and maintain a system of supports, including all bracing and associated items, to retain excavations in a safe manner and to control ground movements. Upon completion of the required tunnel construction, the shafts shall be backfilled as specified. C. All work specified is the responsibility of the Contractor, subject to the approval of the Engineer. Perform work in accordance with all current applicable regulations and codes of Federal, State, and local agencies. In the event of conflict, comply with the strictest requirements. No part of this specification shall be construed as a relaxation of any of these rules, laws, and regulations. D. Construction methods shall satisfy the requirements of this sectionthe CONTRACTOR Engineer s design while utilizing and preserving the inherent strength of the ground surrounding the shafts. The strength of the ground forms the foundation of the permanent support for this shaft. E. Engineer and CONTRACTOR shall coordinate final location and Excavated dimensions and arrangements shown on the Drawings for the shafts are minimum dimensions. Subject to the approval of the Engineer, the Contractor may select such dimensions as he may required to conduct the work, based on space requirements for the equipment used, installation of components, handling of excavated material, methods of construction, and ancillary services. F. Furnish all labor, materials and equipment to install shaft ground support, as shown on the Drawings, for the shaft ground support type determined by the D/B TeamContractor. F. The Contractor s methods of excavation shall be compatible with the requirements for the initial shaft support, as indicated in the referenced specification items or on the Drawings and allowable ground movement. If the selected shaft ground support type fails to provide satisfactory performance within the encountered ground conditions, another support type shall be provided. H.G. Furnish all labor, materials and equipment to install shaft instrumentation and monitoring system as determined by the Engineer. The Contractor s methods of excavation shall be compatible with requirements for the instrumentation and monitoring as indicated in the referenced specification items and as specified in Section Formatted: List Paragraph, Left, No bullets or numbering, Tab stops: Not at 1.13" Formatted: Indent: Left: 0.5", Numbered + Level: 1 + Numbering Style: A, B, C, + Start at: 1 + Alignment: Left + Aligned at: 0.75" + Indent at: 1" I.H. Furnish all material and labor to install and maintain pumps, piping, drains and other facilities

22 for the control, collection and disposal of groundwater from inside the shaft excavation. J.I. The Contractor shall be responsible for furnishing and installing all electrical equipment required to complete shaft construction activities. The Contractor shall also furnish the electrical equipment for all of the auxiliary systems which shall include but not be limited to transformers, panel boards, security lighting, grounding, power for vent fans, sump pumps, disconnect switches, voice communication equipment, office trailers, etc. K.J. Contractor shall provide fencing and/or barricades around shaft excavations as necessary for safety of vehicles and pedestrians working in the area, and as required by BNSF Railway RELATED WORK A. Section 01510: Interim Tunnel Mechanical Systems B. Section 01520: Construction Power and Interim Electrical Systems C. Section 02430: Tunnel Excavation D. Section 02450: Installation of Pipe In Tunnel E. Section 02460: Groundwater Control F. Section 02470: Instrumentation And Monitoring G. Section 03330: Low Strength Controlled GroutDensity Cellular Concrete 1.03 DEFINITIONS A. See Definitions as provided in Section 01070, Definitions SUBMITTALS A. For submittal procedures refer to Section 01300: Submittals. B. Submit to the Engineer the following a minimum of eight weeks before the scheduled start of the applicable activity. 1. Name and qualifications of person responsible for shaft support system design. This work shall be prepared and sealed by a Professional Engineer licensed in the State of Texas. 2. Shop drawings and design calculations indicating arrangement of supports and construction sequence for proposed shaft support system(s). Show the elevation of struts, braces, or other supports as related to the depth of excavation at intermediate stages of construction. Provide details of working slab, drains, and sump construction. Indicate sizes, shapes, and material specifications for all support elements including lagging, if used. Calculations shall include estimates of likely deflections or deformations of the construction shoring system and maximum tolerable values. 3. Breakout plans indicating type of support installed to transfer loads and maintain excavation support and stability of the excavation when commencing tunneling

23 4. Planned actions to develop provisions for protecting adjacent facilities and utilities if monitoring program shows tolerance levels are met or exceeded REQUIREMENTS A. The Contractor shall have the sole responsibility for the design, construction, maintenance, and backfilling of the shaft, as well as the shaft supply system associated with this work. B. The Contractor shall have the sole responsibility for maintenance and protection of existing utilities, structures, and facilities within the zone impacted by the shaft. The zone of impact shall include the zone of ground movement in the vicinity of this work. C. The Contractor shall have the sole responsibility for sizing the shaft within the limits specified and shown on the Drawings. The size of the excavations shall be adequate to construct all structures required and to gain access to tunneling operations for all materials, equipment, and personnel. D. The Contractor shall allow the Engineer and the Owner s representative access to the shafts, and to use the shafts to access tunnel operations. E. Allow the Engineer and the Owner s representative to review monitored data on a real-time basis the instruments as specified in Section 02470, Instrumentation and Monitoring SAFETY A. The method of construction shall ensure the safety of the work, project participants, the public, third parties, and adjacent property, whether public or private. All work shall conform to the requirements of all Federal, State, and local laws and regulations. The Contractor is solely and completely responsible for maintaining safe work conditions at the site at all times. B. The Safety Officer shall administer an accident prevention program, and shall prepare a code of safe practices and an emergency plan. Provide the Engineer with a copy of each prior to starting tunnel excavation. Hold safety meetings and provide safety instruction for new employees. PART 2: PRODUCTS AND MATERIALS 2.01 MATERIALS A. Structural Steel: Structural steel members, such as fabricated connections and accessories, steel W shapes, plate steel, and other structural steel shall conform to the requirements of ASTM A 572 or ASTM A 36, unless otherwise approved. B. Lagging: Lagging between soldier piles shall be timber, steel plate, or reinforced concrete. 1. Timber Lagging: Timber lagging shall be of construction grade and shall be any species that provides a minimum allowable bending stress of 1,100 psi. 2. Reinforced Concrete Lagging: Reinforced concrete lagging shall be designed by the Contractor to safely resist design ground loads with an appropriate safety factor. As a

24 minimum, design shall include evaluation of methods of connection between the panels and the soldier piles, and bending moments in the panels. C. Steel Liner Plate 5. Steel liner plate shall meet the requirements of AASHTO Standard Specifications for Highway Bridges, Division I Design, Section Design of steel liner plate support shall meet the requirements of BNSF and AREMA Part 8 Tunnels 7. Steel liner plate shall be grouted in place within 12 hours of erection. 8. Grout used shall be neat cement grout or sand-cement grout 9. Wales used to back the steel liner plate shall meet the requirements of 2.01 A above. K.C. Sheet Piles: Steel sheet piling shall be continuous interlocking made in accordance with ASTM A 328 or ASTM A 857 or from steel meeting the requirements of ASTM A 36 or ASTM A L.D. Low Strength Controlled Groutean Concrete: LSCG ean concrete shall have a low strength (in the range of 500-1,000 psi) and small aggregate such that it is easily and evenly chipped away for lagging installation. M.E. Backfill Material: Backfill sand shall conform to ASTM C 778 for sand. Plugging material such as Excelsior or dry pack shall be used to prevent backfill sand from running. Alternatively, lean concrete mixed with sand could be used as backfill material. N.F. Geotextile: A non-woven geotextile that provides separation, filtration and retainment of the soils present and compatible with the construction shoring system(s). The geotextile shall have a minimum tensile strength of 225 lbs. in accordance with ASTM D 4632 and a minimum Mullen burst of 450 psi in accordance with ASTM D O. Welded Wire Fabric: 17. Welded Wire Fabric: ASTM A Size: 4 inches x 4 inches W2.9 x W2.9. T.G. Chain Link Fence Fabric: 1. Chain Link Fence Fabric: ASTM A 392. PART 3: EXECUTION 3.01 GENERAL REQUIREMENTS A. Start: Commence shaft excavation only after the Engineer has reviewed and accepted all applicable submittals. B. Methods: Methods of construction for shaft excavations shall be such as to ensure the safety of the work, Contractor s employees, the public, and prevent damage to adjacent property and improvements, whether public or private

25 C. Slab: Provide all excavations with a concrete working slab equipped with a sump to pump out construction water and storm water. D. Protection: 1. Before beginning construction at any location of this project, adequately protect existing utilities and other existing facilities. Design and construct construction shoring system(s) to limit deformations in accordance with that could damage adjacent utilities. In no case shall deformations be more than the response values included in Section 02470, Instrumentation and Monitoring. The repair of or compensation for damage to existing facilities shall be at no cost to the Owner. If settlement or deflections of supports indicates that the construction shoring system(s) required modification to prevent excessive movements, the Contractor shall redesign and resubmit revised shop drawings and calculations at no additional cost to the Owner. 2. Shaft initial ground support system shall extend a minimum of 36 inches above grade in the work site in order to prevent surface water runoff from entering the excavation, as well as having the site graded to promote drainage away from the excavation. E. Excavation: Excavations, including excavation depth at all stages of excavation and support installation shall be compatible with the design sequence established by Contractor s Engineer. shall be to the dimensions as necessary to accomplish the work. Maintain a minimum of 5-feet clear access on all sides of the shaft. Do not excavate more than six inches deeper than the elevations shown or approved. Excavations carried more than six inches deeper than the elevations shown or approved shall be backfilled with approved compacted material or lean concrete at no cost to the Owner. Methods used in making excavations shall not loosen ground beyond the limits of excavation. F. Unsupported Height: The height of unsupported shaft sidewall span shall not exceed three feet in the tunnel access shaft or other excavations. No unsupported sidewall spans will be allowed to exist for longer than 8 hours. G. Welding: All welding shall conform to the applicable provisions of ANSI/AWS D 1.1. C. Support System Monitoring: Install support system monitoring provisions as indicated in the submittals. Install and monitor instrumentation in conformance with Section 02470, Instrumentation and Monitoring DESIGN A. Design construction shoring system(s) and working slabs to withstand earth pressures, bottom heave, equipment loads, applicable traffic and construction loads, and other surcharge loads to allow the safe construction of the tunnel without excessive movement or settlement of the ground, and to prevent damage to adjacent structures, streets, and utilities. Design construction shoring system(s) to be compatible with the ground conditions presented in the GBR and lateral earth pressures and in accordance with AISC and ACI code provisions, as applicable. B. Design each member or support element to support the maximum loads that can occur during construction with appropriate safety factors

26 C. Employ wales, struts, and beams for bracing and lateral support as required for excavation faces supported by soldier piles and lagging or sheeting systems. Provide struts with intermediate vertical and horizontal supports as required to prevent buckling. Provide timber lagging, pre-cast concrete lagging, or steel sheeting as required to retain soil between supports. D. Design a working slab for each excavation final subgrade bottom to provide stable support for construction operations. E. Locate shaft excavation as indicated on the Drawings, unless otherwise approved by the Engineer and Owner. G.E. Design excavation support systems in accordance with all OSHA requirements. H.F. Design excavation support systems and work site layout in accordance with all BNSF requirements. Formatted: Indent: Left: 0.5", Numbered + Level: 2 + Numbering Style: A, B, C, + Start at: 1 + Alignment: Left + Aligned at: 0.75" + Indent at: 1" I.G. Review of the Contractor s plans and methods of construction by the Owner s Engineer does not relieve the Contractor and his/her design consultants of his/her responsibility to provide and maintain an adequate support system achieving the specified requirements WATER CONTROL A. Water control including but not limited to grouting, surface drainage, water removal, and disposal shall be in accordance with Section 02460, Groundwater Control UTILITIES A. Utilities present in the vicinity of the shaft excavation shall be preserved and service continued without interruption. B. Locate and size shaft excavation to minimize conflicts with utilities. D. Location of utilities shown is only approximate. In Field, locate each utility potentially impacted by the work to verify location prior to beginning underground construction at each location. F.B. Coordinate with each utility agency as necessary prior to relocation, hanging, or upgrade of utilities in the vicinity of shaft excavation. The cost of this work shall be borne by the Contractor, whether performed by the Contractor or the utility agency. Formatted: Indent: First line: 0" Formatted: Indent: Left: 0.75", First line: 0", Numbered + Level: 1 + Numbering Style: A, B, C, + Start at: 1 + Alignment: Left + Aligned at: 0.94" + Indent at: 1.19" SOLDIER PILES AND LAGGING A Predrilled Holes: Install piles in predrilled holes or by pile driving, to the tip elevations shown in the approved submittals. Provide casing or drilling mud to prevent caving of holes and loss of ground in predrilled holes. If pile driving is performed, the Contractor shall be solely responsible for all damage to nearby utilities, structures, and other facilities caused by vibrations. Contractor shall abide by all noise regulations and ordinances. B Concrete Encasement: After soldier pile has been seated plumb in the drill hole, encase it