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    SECTION 02750

    EXCAVATION FOR INTERCEPTOR SEWER

   PART 1 - GENERAL

   1.01 SECTION INCLUDES

    A. Construction of a tunnel for a 102-inch minimum inside diameter reinforced concrete or fiberglass reinforced plastic pipe sanitary interceptor sewer. This Section is intended to be primarily functional in nature and to define, in general terms, the work to be accomplished. The Contractor shall have full discretion to select the method of tunnel construction, subject to review by the Engineer.

    B. Open cut excavation for a 102-inch minimum inside diameter reinforced concrete or fiberglass reinforced plastic pipe sanitary interceptor sewer.

   1.02 RELATED SECTIONS

    A. Section 01390 - Health and Safety.

    B. Section 02111 - Waste Material Disposal.

    C. Section 02112 - Hazardous Substances Handling and Disposal.

    D. Section 02222 - Excavation.

    E. Section 02223 - Backfilling.

    F. Section 02570 - Instrumentation.

    G. Section 02751 - Interceptor Sewer.

    H. Section 02316 - Filter Fabric.

   1.03 REFERENCE STANDARDS

    The publications listed below form a part of this specification to the extent referenced. The publications are referred to in the text by the abbreviations only.

    A. American Railway Engineering Association (AREA) Manual for Railway Engineering (applicable sections).

    B. American Association of State Highway and Transportation Officials (AASHTO).

    C. American Society for Testing and Materials (ASTM).

    1. ASTM A36 - Standard Specifications for Structural Steel.

    2. ASTM A82 - Standard Specifications for Steel Wire, Plain, for Concrete Reinforcement.

    3. ASTM A185 - Standard Specifications for Steel Welded Wire Fabric for Concrete Reinforcement.

    4. ASTM A283 - Standard Specifications for Low and Intermediate Tensile Strength Carbon Steel Plates.

    5. ASTM A307 - Standard Specifications for Carbon Steel Bolts and Studs, 60,000 PSI Tensile Strength.

    6. ASTM A328 - Standard Specifications for Steel Sheet Piling.

    7. ASTM A496 - Standard Specifications for Steel Wire, Deformed, for Concrete Reinforcement.

    8. ASTM A615 - Standard Specifications for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement.

    9. ASTM C33 - Standard Specifications for Concrete Aggregates.

    10. ASTM C150 - Standard Specifications for Portland Cement.

   1.03 SUBMITTALS

    A. Submit, for review, complete working drawings showing details of the proposed method of construction and the sequence of operations to be performed during construction. Show the method of tunnel excavation, muck removal and disposal, type and method of installation of the primary tunnel support system, work shaft locations and construction, shoring and bracing, and dewatering proposed to be used. The submittal shall be reviewed by the Engineer prior to placing orders for materials or equipment. The drawings shall be sufficiently detailed to allow the Engineer to judge whether or not the proposed materials and procedures will meet the Contract requirements.

    B. Submit for review the analysis and structural design of the primary tunnel support system.

    C. Submit for review the analysis and structural design of the trench support system for the open cut portion of the sewer. Show the method of construction and the sequence of operation to be performed during construction. Show the method of bottom stabilization.

    D. Submit for review rock bolting plan and design.

    E. Submit, for review, the layout and design, including structural design of shoring and bracing, of all shafts. Include a design for the temporary cover of shafts where required. All shaft structures and covers shall be capable of carrying an AASHTO H-20 load.

    F. All structural designs submitted by the Contractor shall be sealed by a Professional Engineer registered in the State of Tennessee.

    G. Submit for review, details on safety, lighting, ventilation, and electrical systems.

    H. Submit for review details of grouting plan for filling the voids between the pipe and excavation and the voids between the pipe and tunnel support system.

    I. The Engineer will base the review of submitted details and data upon consideration of requirements for the completed work, safety of the work for the public, possibility of damage to public and/or private property and utilities, and possibility of unnecessary delays in the execution of the work to be construction under this contract. Such review by the Engineer shall not be construed in any way of relieving the Contractor of his responsibilities under the Contract.

    J. Submit for review, details of water control, treatment, and disposal.

   1.04 DESIGN CRITERIA

    A. The primary tunnel support system shall be designed for appropriate loading conditions, corresponding and deflection criteria, including but not limited to: the overburden and lateral earth pressures, handling and installation stresses, loads imposed by the tunnel shield or tunnel boring machine thrust jacks, subsurface soil, rock, and water loads, grouting, and all other conditions of service. Contractor shall be responsible for the design of the primary tunnel support system to carry the thrust of any jacking or other construction forces or loads anticipated.

    B. The design criteria to be used at railroad crossings shall be Cooper E-80 locomotive loading distributions in accordance with AREA specifications for culverts. Additive loadings for multiple tracks shall be accounted for in the design.

    C. The design criteria to be used for truck loadings shall be HS-20 vehicle loading distributions in accordance with AASHTO.

   1.05 TUNNEL CLASSIFICATION

    A. It is anticipated that portions of the tunnel will be classified as potentially gassy as defined by OSHA 29 CFR part 1926.

    B. The tunnel has the potential under certain conditions to be up-graded to gassy during portions of the construction period.

    C. The Contractor shall plan the work, equip the tunnel, and develop appropriate operational procedures in the event the tunnel becomes classified as gassy. The Contractor should base his plan on the requirements of OSHA 29 part 1926 and any local or fire ordinances that may apply.

    D. The costs of upgrading mechanical and electrical equipment including the tunnel boring machine and all systems for operations in potentially gassy or gassy conditions as defined above will not be paid for if, during construction, either initially, or at any time, the tunnel is classified from non-gassy to gassy. Cost that will be paid for if hazardous substances are encountered are defined in section 01025.

   PART 2 - PRODUCTS

   2.01 SUPPORT SYSTEMS

    A. "Primary Tunnel Support System" shall be defined as the tunnel support designed and installed by the Contractor for ground stability during construction preparatory to the installation of the sewer line. Such method of construction shall be of the Contractor's choosing, in accordance with this Specification.

    The Listing of the various methods or reviews by the Engineer of Contractor's submittals shall not be construed by the Contractor as an endorsement or implied warranty by the Engineer that all such methods are constructible or will work for the specific subsurface soils encountered.

    B. The primary tunnel support system may consist of rock dowels with mine straps, steel ribs, steel ribs and lagging, steel liner plates, reinforced shotcrete, precast concrete segments, steel casing pipe, or combinations of these. Lagging may be timber, or steel. Contractor may utilize additional support elements including but not limited to rock bolting, as required to provide a safe, stable excavation.

    C. A steel liner shall be the primary support system for tunneling under railroad right of way.

    D. A temporary bulkhead will be installed at the terminal end of the tunnel with steel liner plate under the railroad right-of-way. After the open cut is completed in railroad right-of-way the bulkhead is to be removed and the steel liner plate will be extended in the open cut area through the railroad right-of-way.

    The bulkhead shall be capable of resisting the lateral earth and hydrostatic pressure and be designed to be removable without damaging the sewer pipe or primary steel liner.

    The design of the bulkhead shall be reviewed by the Engineer and approved by Nashville and Eastern Railroad.

    E. Where the use of the following materials is required, such material shall be in accordance with the following minimum standards :

    Reference

    Material Standards

    Cement ASTM C150

    Structural Concrete See Section 03300

    Reinforcing Steel Wire ASTM A82 or A496

    Reinforcing Steel Wire Fabric ASTM A185 or A497

    Reinforcing Steel Bars ASTM A615, Grade 60

    Sand and Aggregate ASTM C33

    Structural Steel ASTM A36

    Steel Piles, Sheets ASTM A328

    Rings and Ribs ASTM A36

    Steel Plates ASTM A36 and A283

    Lumber and Timber Hardwood, sound or better, as defined by Commercial Standard C560

    Steel Casing Pipe AWWA C200

   2.02 STEEL LINER PLATES

    A. Except as otherwise specified, materials shall be furnished according to the applicable requirements of AREA Manual for Railway Engineering. The liner plate shall be fabricated from hot-rolled carbon-steel sheets or plates, conforming to ASTM A569.

    B. Bolts and nuts shall conform to ASTM A307, Grade A. All nuts and bolts shall be galvanized.

    C. All plates shall be punched for bolting on both longitudinal and circumferential seams and shall be fabricated to permit complete erection from the inside of the tunnel. All plates shall be of uniform fabrication and those intended for one size tunnel shall be interchangeable.

    D. The material used for the construction of these plates shall be new.

    E. Minimum thickness of the metal for these steel plates shall be 8 gauge in order to meet minimum railroad permit requirements. However, gauge shall be thicker than 8 gauge as necessary to meet actual design criteria.

    F. Steel liner plates shall be equipped with approximately 2-inch diameter grout holes furnished with plugs. Holes shall be located at no more than every other plate and shall be staggered.

    G. After the plates are formed to shape and after all holes are punched, the plates shall be galvanized on all surfaces by the hot-dip process. A coating of prime western spelter (zinc), or equal, shall be applied at the rate of not less than 2 ounces per square foot of double exposed surface. If the average spelter coating as determined from the required samples is less than the amount specified above, or if any one specimen shows a deficiency of 0.2 ounce, the lot shall be rejected. Spelter (zinc) coating shall be of first-class commercial quality free from injurious defects such as blisters, flux and uncoated spots.

    H. Field coating material shall be asphalt mastic, Trumbull 5X, or approved equal, and shall be applied with hydraulic spray equipment using a minimum of 2,400 pounds pressure at the nozzle tip. The material shall be supplied at spraying consistency and shall be applied both to the outside and inside of the liner plates. In lieu of spraying asphalt mastic, plates may be hot-dipped in asphalt mastic to produce a similar coating. The coating shall meet all AREA specifications.

    I. Gaskets shall be installed between liner plates to control water seepage.

    J. Steel ribs used with liner plates shall be in accordance with paragraph 2.04.

    K. The Contractor shall submit the design calculations to the Engineer. All steel liner plate designs shall meet the following minimum factors of safety:

    Seam Strength = 3

    Buckling = 2

    Installation Stiffness = 2.5

   2.03 STEEL CASING PIPE

    A. Casing pipe shall be new, uncoated welded-steel pipe, manufactured in accordance with AWWA C200. The design stress in the pipe wall shall be 50 percent of the minimum yield point of the steel or 18,000 psi, whichever is less when subjected to the loading conditions. The design deflection to be used in determining wall thickness shall not exceed 3 percent of nominal casing pipe size.

   2.04 STEEL RIBS AND LAGGING

    A. Steel ribs and auxiliary structural members shall be free of defects which may impair or reduce their structural integrity. Ribs shall be accurately curved to the proper radius of the tunnel section (or shaft section) and rib segments shall fit closely for bolted connections at segmental and transverse joints.

    All steel appurtenances required for the installation of the ribs such as tie rods, bolts, splice plates, dutchmen, drift pins, etc., shall be provided with the ribs.

    B. Minimum factors of safety:

    Buckling = 2

    Stiffness = 3

    Installation Stiffness = 3

   2.05 ROCK BOLT SYSTEM

    A. Rock bolt system shall be as manufactured by Williams Corp. or approved equal. Contractor to submit rock bolting plan and design for approval by the Engineer.

   2.06 FILTER FABRIC

    See Section 02316, Filter Fabric, for requirements of material and minimum installation requirements. Contractor shall install additional fabric, and backer rods, as required to prevent loss of fine-soil sediments into the tunnel.

   PART 3 - EXECUTION

   3.01 GENERAL

    A. Method of construction for the tunnel and open cut shall be such as to ensure the safety of the work, the Contractor's employees, the public, and adjacent property, whether public or private.

    B. All work of dewatering, excavating, lining, grouting, and construction of the tunnel and open cut shall be so executed that ground settlement is minimized; the completed interceptor sewer and primary tunnel support system will have full bearing against earth/rock and no voids or pockets will be left in any portion of the work.

    C. The Contractor shall monitor project conditions 24 hours per day, 7 days per week.

   3.02 SURVEY CONTROL OF LINE AND GRADE

    A. The Engineer will establish the horizontal control points and bench marks indicated on the Contract Drawings. The Contractor shall check these horizontal control points and benchmarks at the beginning of the Contract period and report any errors or discrepancies to the Engineer.

    B. Use the horizontal control points and benchmarks established by the Engineer to furnish and maintain all reference lines and grades for the tunnel and sewer line construction.

    C. Submit, to the Engineer, copies of field notes used to establish all lines and grades; however, the Contractor remains fully responsible for the accuracy of this work and the correction of it, as required.

    D. The Contractor should be aware that settlement of the ground surface may occur during construction of the tunnel which will affect the accuracy of the monuments established by the Engineer. It shall be the Contractor's responsibility to detect and report such movement.

    The locations of the permanent benchmark are indicated on the Contract Drawings; the Contractor can use these to verify temporary benchmark accuracy. Advise the Engineer and the Owner of any settlement affecting the permanent monumentation.

   3.03 TUNNELING DATA

    Daily logs of construction events and observations shall be submitted on at least the following:

    A. location of face by station and progress of tunnel drive during shift;

    B. observation of lost ground and other signs of ground movement;

    C. location and elevation of significant soil strata boundaries and brief soil descriptions;

    D. groundwater inflow location and rates

    E. The submittal shall also include field forms for establishing and checking line, grade, and ground at TBM face.

   3.04 GROUNDWATER CONTROL

    A. General

    1. Contractor shall include in his bid price per lineal foot of interceptor sewer the handling and disposal of up to 1500 gallons per minute of groundwater inflow. The Contractor is to include in his bid price per lineal foot of sewer the cost for testing groundwater as specified in Appendix "D" regardless of the amount of groundwater encountered.

    2. Contractor is responsible for obtaining all permits and approvals associated with discharge from dewatering operations. The method of controlling groundwater shall be submitted to the Engineer for his review. All federal, state, and local regulations shall be adhered to by the Contractor. Appendix "D" contains the Metropolitan Nashville Department of Water and Sewerage Services groundwater discharge requirements.

    B. Tunnel Construction

    1. If the engineer determines that a discrete source of inflow into the excavation should be reduced, the cost of reducing the inflow will be paid for on a time and material basis including the cost of repairing equipment due to the water inflow. However, downtime to reduce the inflow and repair the equipment will not be paid for, but the time will be added to the contract time. The Contractor shall store adequate equipment and/or materials on-site in order to proceed in a timely manner to reduce inflows.

    C. Open Cut Excavation

    1. The maximum allowable groundwater or stormwater pumping from the open excavation will be one (1) gpm per foot of open trench.

    2. The cost for dewatering and providing the trench support system shall be subsidiary to the contract unit price per lineal foot for 102-inch interceptor sewer in open cut.

   3.05 EQUIPMENT

    A. No gasoline-powered equipment shall be permitted in the tunnel or construction shafts.

    B. Diesel, intrinsicly safe electrical, or air-powered equipment will be acceptable, subject to applicable federal and state regulations.

    C. Tunnel Boring Machine

    1. It is intended that the work from the access shaft southward be excavated with a full face tunnel boring machine. Any other method or equipment which the Contractor can demonstrate will produce the specified results will be considered.

    2. The tunnel boring machine shall be capable of minimizing loss of ground ahead and above the machine. In cases where the bentonite layer is located near or above the crown of the excavation, stabilization of the roof rock will be required prior to passage of the TBM tail shield.

    3. Provide a bi-directional drive on the cutter head wheel to minimize drift due to rotation.

    4. Provide means for maintaining the tunnel face under wet and adverse rock or soil conditions.

    5. Provide jacks on the shield which will distribute jacking forces without damaging rock sidewall or previously installed primary supports.

    D. Provide equipment to adequately ventilate the entire tunnel at all times during construction.

    E. Tunnel lighting shall be in accordance with OSHA Regulations.

    F. Provide portable testing equipment for carbon monoxide gas, methane, carbon dioxide, hydrogen sulfide gas, volatile organic compounds and oxygen deficiency.

    G. Provide visible and audible automatic gas alarms and equipment shut-offs to detect explosive gases. Locate the alarm near the tunnel face at all times.

    H. All electrical systems shall be 480V or less unless approved by the Engineer. Motors and controls shall be explosion proof in accordance with OSHA regulations.

    I. Provide a primary and an alternate communication system.

   3.06 SHEETING, LINING, SHORING, AND BRACING

    A. Furnish, place, and maintain all sheeting, lining, shoring, and bracing required to adequately support the sides, floor, and roof of all excavations, including the open cut excavation, tunnel diversion structures and tunnel access shaft.

    B. Additional Shoring and Bracing: If, in the opinion of the Engineer, the methods being employed by the Contractor are not considered reasonably safe, the Engineer may require, and the Contractor shall provide, additional shoring and bracing to afford the required degree of safety. The provision of added precautions shall in no way relieve the Contractor of the sole and final responsibilities for safety of work or public.

   3.07 SHAFTS

    A. The tunnel access shaft easement location is shown on the Contract Drawings. Requests for additional shafts or adjustments to locations must be submitted by the Contractor to the Engineer for approval. If approved, all requirements associated with requests must be provided by the Contractor. These requirements include, but are not limited to, traffic control plans, regulatory governmental agencies' permits, coordination for utility relocations, restoration of disturbed areas, and other submittal requirements listed in this Specification.

    B. Contractor shall make every effort to locate shaft at locations as to cause least disruption to the daily routine of business and commercial establishments, residences, and traffic. Locations of shafts are subject to regulatory agency requirements.

    C. Size of Shaft: The size of the shaft shall be adequate to fit within the permanent easements and provide adequate room to meet the Contractor's operational requirements for tunnel construction.

    D. Construction of Shaft: Work for shaft shall be in accordance with Section 02222, Excavation, and Section 02223, Backfilling.

    E. Traffic: Contractor shall submit a traffic control plan for approval by the Engineer around the shaft site.

    F. Safety: Provide and install a ladder with a safety cage in the shaft and a chain link fence as specified in Section 01500 around the shaft site as shown on the Contract Drawings. Also provide and install a safety cover over the shaft opening when no construction operations are being performed. Said cover shall support a weight of 200 lbs per square foot. The design and material used for the cover must be approved by Engineer.

    G. Vertical shafts shall be protected from surface flooding during construction. The Contractor shall develop and submit contingency plans for protecting all work from flooding equivalent to the 100 year flood elevation from both the Cumberland River and/or Browns Creek, whichever may affect a particular excavation.

    H. Fence must remain in place until tunnel is completed through shaft and the shaft backfilled and surface restoration is started.

    I. Diversion structures used in the construction of the tunnel as access shafts shall conform to the above requirements A. through G.

   3.08 TUNNEL EXCAVATION

    A. Tunnel Excavation

    1. Tunnel excavation shall be within the easements and rights-of-way, to the lines and grades designated on the Contract Drawings, and utilize methods which include due regard for safety of workmen, adjacent structures, utilities and the public. Methods of tunnel excavation shall be at the Contractor's option, subject to the review of the Engineer. Shape the excavation to fit the sewer pipe section and to be of sufficient size to allow the construction of the sewer pipe to the lines and grades indicated on the Contract Drawings.

    2. Furnish all necessary equipment for tunnel construction, provide adequate lights, ventilation, signal systems, communication systems, fire extinguishers, safety equipment and other equipment required, and maintain such equipment in good repair. Locate equipment powered by combustible fuels at suitable distances from shafts and so protect as to prevent the possibility of explosion and fire in shafts or the tunnel.

    3. Unless otherwise specifically designated on the Contract Drawings or ordered in writing by the Engineer, the installation of a tunnel support system, rock bolts, or other type of bracing is at the option of the Contractor. It will be the Contractors responsibility to maintain worker safety and maintain the structural integrity of the rock face of the tunnel during construction operations until the sewer pipe is installed and grout placed in the annular space between the rock face and the sewer pipe. If voids greater than 6-inches in depth occur along the top or sides of the tunnel the Contractor shall brace the affected tunnel section by rock bolts, liner plate, rib and lagging or other methods as approved by the Engineer.

    4. During shut-down periods support face of excavation by positive means; when the shut-down duration exceeds more than 24 hours, fully brace the face and shove the shield tight against it.

    B. Size of Tunnel: The tunnel shall be of sufficient size to permit efficient excavation operations, to provide sufficient working space for placing the tunnel lining if required, and to allow for construction of the sewer as shown on the Contract Drawings or indicated in the Specifications. Determination of an adequate tunnel size and section to meet these requirements shall be the sole responsibility of the Contractor. It shall be understood and agreed that the dimensions shown on the Contract Drawings represent the minimum dimensions acceptable to the Engineer and do not necessarily represent the size and/or section suitable for the construction methods or operational procedures as may be proposed and/or conducted by the Contractor. 

    C. Primary Tunnel Support System

    1. Provide a primary tunnel support system for the tunnel where indicated on the Contract Drawings or at locations to provide bracing in accordance with paragraph 3.08 A.3 above.

    The primary tunnel support system shall be capable of supporting the earth load and hydrostatic forces and resisting construction loads, including jacking forces from the tunnel boring machine for at least 2 years. Liner plates, if used, shall be installed with gaskets to reduce seepage influx.

    D. Supplemental Primary Tunnel Support System

    Supplemental primary tunnel support system shall be as specified above in paragraph C. Supplemental primary tunnel support system is to be used to provide structural integrity to the tunnel in locations other than shown on the plans at locations approved by the Engineer in writing. The supplemental primary tunnel support shall be readily available and be designed to support a 3550 pound per square foot load. A minimum of 100 linear feet of emergency type primary tunnel support, capable of supporting an equivalent load of 3550 psf, be made available at all times during tunneling operations. Emergency support shall not consist of bolts, straps or dowels, but shall support the full bore circumference and be designed to accommodate the final liner.

    E. Earth Movement

    1. The Contractor is advised of the proximity of a railroad, buildings, structures, roads, and utilities to the work. Take precautions to avoid damage or settlement to these. Precautions shall include the use of construction methods and equipment to minimize loss of material at the tunnel face. The maximum allowable ground settlement is one inch.

    2. In the event any movement of earth is detected, the Engineer may order the work stopped and secured. Before proceeding, correct any problems causing or resulting from such movement.

    F. Tolerance

    1. Control the excavation of the tunnel and construction of the primary liner if required to allow construction of the interceptor sewer within 3-inches on line and 1-inch on grade.

    2. When excavation is off line and grade, return to plane line and grade at the rate of 3-inches per 100 feet.

    3. Survey the crown, invert, and springline of the primary support system or at rock face at 100-foot intervals to ensure the alignment is within the tolerances specified. Conduct the survey immediately behind the tunnel excavation to allow immediate correction of misalignment.

    4. If the Contractor is unable to maintain these tolerances, he shall bear full responsibility for correction. If those tolerances are exceeded and redesign of structures is required, the Contractor shall obtain the services of a Professional Engineer registered in the State of Tennessee, at his own expense, for the redesign. Design and drawings showing the changes shall be submitted to the Engineer for review.

    G. Grouting Between Final Liner and Tunnel Excavation Surface

    1. Furnish and operate suitable equipment for all grouting operations.

    2. Grout shall consist of a uniform mixture of one part by weight of portland cement to three parts by weight of clean sand of suitable gradation, or four sacks of masonry cement per cubic yard of sand, at the Contractor's option, together with approved air-entraining agent and a minimum of clean water for placing.

    3. Fill all excavation outside the tunnel liner with pressure-applied grout or other approved fill unless otherwise directed by the Engineer. Use care in grouting operations to prevent damage to adjacent utilities or other properties. Pressure used in grouting shall not be great enough to distort or imperil any portion of the work.

    4. All voids outside the limits of the tunnel excavation created by caving or collapse of earth cover over the excavation or by other cause shall also be completely filled with grout.

    5. All grouting to eliminate voids outside the tunnel limits shall be at the Contractor's expense.

    H. Excavation in and Adjacent to Railroad Right-of-Way

    1. Construction of the sewer between Stations 5 + 00 and 6 + 75 shall include the installation of steel liner plates with gaskets. The liner plates shall be capable of supporting the earth load and hydrostatic pressure as well as the railroad live load. The excavation and installation of the steel liner plates shall be in accordance with requirements of the Nashville and Eastern Railroad. Grouting between the steel liner plate and tunnel surface shall be in accordance with Section 3.08 G. The Contractor shall obtain the railroad permit and all approvals of designs from Nashville and Eastern Railroad prior to any work inside railroad right-of-way.

    I. Rock Bolting

    1. Rock bolts may be used to provide structural integrity to the tunnel excavation where approved in writing by the Engineer. A rock bolting plan and system design must be submitted to the Engineer for approval and must be sealed by a Professional Engineer registered in the State of Tennessee.

   3.09 Open Cut Excavation

    A. The open cut segment of the 102-inch interceptor sewer shall be in conformance with applicable portions of Section 02222 - Excavation, and Section 02223 - Backfilling, unless otherwise specified below.

    B. The additional requirements are as follows:

    1. Installation of trench support system, pipe envelope and backfill shall be in accordance with the typical section for 102-inch interceptor sewer in open cut shown on the Contract Drawings. This work shall be included in the contract unit price per lineal foot for 102-inch interceptor sewer in open cut.

    2. The sewer will be installed under a high pressure 8-inch liquid petroleum pipeline at two locations as shown on the Contract Drawings. The liquid petroleum pipeline must remain in service and be supported in accordance with the details shown on the Contract Drawings. This work shall be paid for at the lump sum contract price for high pressure liquid petroleum pipeline support, including both locations. All work shall be approved by the Colonial Pipeline Company. Colonial Pipeline Company requirements are included in Appendix "C".

    3. In areas where the Contractor will be operating equipment, the high pressure liquid petroleum pipeline shall be protected by the construction of a concrete slab over the liquid petroleum pipeline. This work shall be included in the contract unit price per lineal foot for 102-inch interceptor sewer and open cut.

    C. Work on Railroad Right-of-Way

    1. The 102-inch sanitary sewer will be constructed by open cut excavation in a portion of the railroad right-of-way. The main railroad track and one spur line shall remain operational at all times. Approximately 12 trains per 24-hour period are expected to utilize these tracks. The Nashville and Eastern Railroad must approve the Contractor's design of the trench support system (including the bulkhead at Station 5+65) and all operations of the Contractor which may impact railroad operations. The Contractor shall provide on-site coordination with the railroad and obtain all permits required by the railroad.

    2. The Nashville and Eastern Railroad will relocate the northerly spur track switch point to the adjacent track by their own forces. The cost of work by the railroad is included as an allowance for relocation of railroad spur switch point.

    3. Work in railroad right-of-way shall include installation of gasketed segmental steel liner plates in accordance with AREA specifications. The steel liner plate in the open cut portion must extend and be identical to and connected with the steel liner plate specified for the tunnel section. The trench support system including along the sides of the trench shall remain in place in the railroad right-of-way, the backfill under the railroad track ballast shall be the same material as specified for the pipe envelope around the open cut interceptor sewer, all as detailed on the Contract Drawings.

   3.10 INSTRUMENTATION

    A. Instrumentation shall be installed and maintained by the Contractor to monitor ground behavior and to provide a timely warning for the implementation of remedial measures to prevent possible damages to structures, equipment and utilities.

    B. Instrumentation system shall be as specified in Section 02570, and as shown on the Contract Drawings.

   3.11 SOIL TESTING

    A. Prior to off-site disposal of excavated materials, the Contractor shall employ a qualified environmental consultant to perform sampling and testing to determine the environmental classification and proper disposal requirements at each soil excavation and hazards associated with worker exposure to the uncovered material. The Contractor shall contract with a laboratory approved by the Engineer and pass all costs associated with soil testing. These costs are to be merged into the bid price for the sewers.

    At each separate excavation area, the number of discrete samples to be collected and field screened with an Organic Vapor Analyzer (OVA) shall be based on one sample per every 50 cubic yards of material. The discrete samples shall be fresh (not surface samples) and must be evenly distributed throughout the entire excavated volume. The field screening is to be used to determine which sample has the greatest potential for contamination. The sample(s) with the highest OVA reading, or a randomly selected sample if none are highest, shall be submitted for laboratory testing for total Toxicity Characterization Leaching Procedure (TCLP), which includes EPA methods 1311, 3010, 6010, 7470, 3510, 8080, 8240, 8270, 8150, 9045, 9095, 1010, cyanide, sulfide, DRO, and GRO. The number of samples required for laboratory testing will be determined by the total excavated volume at each separate excavation site. A minimum of one laboratory test is required at each separate site for up to 100 cubic yards, with one additional laboratory sample submitted for each additional 250 cubic yards of material above the initial 100 cubic yards. The pre-disposal testing shall be performed by exploratory borings on a grid pattern prior to excavation.

    B. Excavation from the tunnel construction and rock excavation at the diversion structures and shafts shall comply with the testing requirements listed above except that the lab tests shall be performed at the rate of one lab test per 200 lineal feet of tunnel construction and one test of rock excavation at each diversion structure and shaft location.

    At the diversion structures and shafts a continuous split spoon sample shall be obtained and tests performed on a composite sample.

    C. The results of all field screening and laboratory testing results shall be maintained by the environmental consultant in a bound volume including a scaled site map showing all sampling points. Copies of the results, the environmental consultant's interpretation of the environmental classification of the soil and the resulting material disposition shall be provided to the Engineer at least monthly. The Contractor's environmental consultant shall analyze the results and provide those results to the Contractor and the Engineer along with recommendations and cost estimates for disposal options that conforms to Metro, Tennessee Department of Environment and Conversation, EPA and disposal facility requirements.

   3.12 DISPOSAL OF EXCESS MATERIAL

    All excess excavated material shall be removed from the job site. Removal and its disposal from the job site shall be in accordance with Section 02111, "Waste Material Disposal" or Section 02112, "Hazardous Substances Handling and Disposal", as applicable.

    END OF SECTION