DESCRIPTION
Relocation of Roslyn Road to eliminate the Grade Crossing with the Long Island Rail Road (LIRR) in Mineola,NY requiresthatthe New York PowerAuthority’s(NYPA)high pressure fluid filled 345kV pipe cable circuit (Y-49) be lowered on both the north and south side of the present LIRR mainline crossing to permit construction of the new roadway under the LIRR. The cable circuit, consists of one 8 NPS (8-5/8”OD)corrosion protected steelcable pipe,one 5 NPS (5-9/16”OD)corrosion protected steel fluid return pipe and two 76.2 mm (3” OD)PVC conduits,containing FiberOptic cable,encased in a concrete envelope offluidized thermalbackfill(FTB)thatisapproximately 1.22 m (4’)wide and 0.61 m to 0.76 m (2’to 2-1/2’)in depth.The 12 NPS steel Keyspan gas main will require special support and maintenance when exposed within the trench.
Referring to the Contract Drawings for Plan/Profile and sections of the work on the north side of the LIRR, starting just south of East 2nd Street, a 38.1 m (125’)section ofthepipe circuitmustbe exposed and thecenterportion ofthe section lowered approximately 0.5 m (1.6’);on thesouth side oftheLIRR,a 76.2 m (250’)section ofthe pipe circuitmustbe exposed and the centerportion ofthesection lowered approximately 1.23 m (4.0’).
MATERIALS
Materials required to perform the cable circuit lowering will consist of the following:
a. Approved material consisting of heat-shrinkable wrap-around repair sleeves and hand applied tape to repair any damage to the steelpipe’s1.52 mm (60 mil)thick polyethylene corrosion protective coating.
b. Temporary Wood Sheeting for trench conforming to Subsection 552-2.02A.
c. Wood sheeting and support members to fabricate bend restrictors to prevent kinking steel pipes as they depart from the remaining FTB enclosure.
d. Material for the support structures necessary over the excavation to support the pipes/conduits during excavation of the soil on either side of the enclosure down to the final required depth. e. Sand bags to support the pipes off the trench bottom and position the conduits prior to
embedment in a new FTB enclosure.
f. Backfill material to reconstitute trench conforming to the specifications for select granular fill, when excavated material cannot be reused.
g. Interim wood sheeting to form the new FTB envelope conforming to Subsection 552-2.03A. h. Pressure rated full-circle pipe repair clamps for both the 8 & 5 NPS steel pipes for uses in the
event either pipe is damaged, resulting in a fluid leak, during any phase of the circuit lowering operation.
i. Fluidized Thermal Backfill (FTB) to reconstitute the concrete envelope around the repositioned pipes and conduits.
i.1 FTB shall be composed of fine and coarse aggregate, cement and a fluidizing agent. i.2 Coarse and fine aggregate shall conform to ASTM Standard C 33 with the exception
that the coarse aggregate shall be round pea gravel and limited in size to a maximum of 9.5 mm (3/8 in).
i.3 Cement shall be Type I conforming to ASTM Standard C 150.
i.4 Fluidizer shall be fly ash. The fly ash shall be Pozzolanic grade as used in fly ash concrete conforming to ASTM Standard C 618.
i.5 Mix proportions kg/cubic meter (pounds/cubic yard) shall be Type A as specified below: Component Materials
Coarse Aggregate - 9.5 mm (3/8”) 800.9 kg (1,350 lbs) Fine Aggregate (Sand) 1,133.1 kg (1,910 lbs) Cement (Type I) ASTM C 150 20.8 kg ( 35 lbs) Fluidizer:
Fly Ash 118.7 kg (200 lbs)
Water 220.1 kg (371 lbs)
i.6 Batching should be done by mass. If this is not possible, volume batching shall satisfy the specified mix proportion by mass. Batching and mixing may be made in a central plant and supplied by ready mix concrete trucks.
Fly ash may be added and mixed either in a central batching plant or added to ready mix trucks on site and blended. Fly ash shall be added in dry powder form.
Alternatively, on site batching and mixing may be permitted provided proper facilities are used. i.7 FTB supplied in slurry form shall have a consistency that will enable it to flow readily to fill the
trench ortunnel,with no vibration spreading required.Flowsof177.8 mm (7”)fortrench applications are required and shall be measured in accordance with the following procedures:
i.7.1 Apparatus
i.7.1.1 Mold - The test specimen shall be formed in a mold made of mild steel. The mold shallbeacylinder76.2 mm (3”)insidediameterby 152.4 mm (6”)high, open atboth ends.Theminimum wallthicknessshallbe3.2 mm (1/8”). i.7.1.2 Tamping Rod - The tamping rod shall be a round, straight metal rod, 12.7 mm
(1/2”) in diameter and approximately 203.2 mm (8”) long, with a hemispherical tip.
i.7.1.3 Test Plate - The test shall be carried out on a suitable metal plate to provide a uniform flowing surface.Itshould beofmetal,ofsize508 mm x 508 mm (20” x 20”)and ofasuitablethicknessto remain rigid.Thetestsurfaceshallbe plain and smooth.
i.7.1.4 Rulers - Two 304.8 mm (12”)rulers,graduated in millimeters(inches) shall be provided.
i.7.2 Sample
i.7.2.1 The sample of test mix shall be representative and obtained in accordance with ASTM Standard C 172.
i.7.3 Procedures
i.7.3.1 Dampen the mold and place it in the center of the dampened level test plate. Fill to overflowing with the test mixture and compact with 5 strokes of the tamping rod uniformly distributed over the cross section of the surface.
i.7.3.2 Strike off the surface of the test mixture, remove any material that falls in the area around the mold base, and wipe the, test plate clean.
i.7.3.3 Lift the mold straight up slowly, allowing all of the material to flow out of the mold onto the base.
i.7.3.4 Determine the average diameter of the resulting flow by measuring the diameter across two points at 90 degree intervals.
i.7.3.5 Determine the maximum height of the flow material by standing the mold on the test plate adjacent to the flow material, resting the edge of one ruler across the diameter of the top of the mold. Allowing it to extend out over the flow material, measure the minimum "slump" of the material. Subtract the minimum slump from the height of the mold, to determine the maximum height of the flow.
i.7.4 Recording
i.7.4.1 Record the flow in terms of average diameter in inches to the nearest 2.5 mm (0.1”).Thisaveragediameter(Flow)shallbeaminimum of178 mm (7”). i.7.4.2 Record the height of the flow, as measured in paragraph g.3.5, to the nearest
2.5 mm (0.1”).
i.7.4.3 Record any segregation of solids, bleeding at the edges or any other unusual conditions.
j. Fiber Optic cable shall meet or exceed the following: Single mode, loose tube, 12-fiber optical cable, as manufactured by Corning Cable Systems part number 012RW4-T4100A20 or equivalent. Cable shall be all dielectric, non-armored, 2700N(600lbf) tensile strength, 0.35/0.25dB attenuation at 1310/1550nm, and PE jacket. Provide minimum reel of 1,524 meters (5000 feet) length with all associated splicing hardware.
k. Materials for the temporary support and maintenance of the 12 NPS KeySpan gas main shall be in accordance with the Contract Documents.
CONSTRUCTION DETAILS
The relocation ofRoslyn Road notonly involvesthe lowering ofNYPA’sY-49 cable circuit but also the proposed installation of a 18 inch RCP Sanitary Sewer and a KeySpan 12 NPS gas line adjacent to NYPA’scircuiton the westside,and a 18 inch RCP Storm Sewer and 12 NPS Water line on the east side of the circuit. As a result, construction details for lowering the NYPA circuit will be governed by the construction schedule for these proposed utility additions and will require coordination with other Contractors, one of which will be KeySpan. Temporary support and maintenance of the existing 12 NPS steel gas main where exposed within the trench will be necessary.
The main area of concern is the trench design required for exposing and lowering the NYPA circuit. Addressing only the NYPA circuit,a trench width of2.44 m (8’)isrecommended to provide room on either side of the FTB envelope for removal of the envelope without subjecting the encased pipes and conduits to the risk of external damage.
1. Trenching
Excavation shall conform to Subsection 206-3.01 with the following additions:
a. The present pipe system is located under the edge of the northbound lane of Roslyn Road at a depth ofapproximately 0.91 to 1.22 m (3’to 4’)and,isencased in a1.22 m wide x 0.61 m to 0.76 m deep (4’widex 2’deep)envelope offluidized thermalbackfill(FTB).The originalFTB backfill had a 28 day minimum compressive strength of 345 kPa (50 psi) and a maximum of 1034 kPa (150 psi). The Contractor shall be responsible for exposing the envelope and removal of all FTB from around the PVC conduits, the fluid return pipe and cable pipe without damage to either the PVC conduits or the corrosion protective coating on the steel pipes or the steel pipes. During exposure of the cable system, the pipes may be pressurized at 1379 kPa (200 psi)fluid pressure but will not be energized. The fluid within the pipes is an alkylbenzene containing no additives injurious to personnel or the environment, should a leak occur. Material Safety Data Sheets will be provided by NYPA.
The method of pipe/conduit exposure is optional but must assure personnel safety and proper support of the trench and pipe/conduit system at all times. Sheeting must be provided for trench depthsexceeding 1.52 m (5’)using approved sheeting methods.The Contractorshallsubmit details of the exposure method, including location and type of sheeting proposed for review by NYPA and shall obtain approval from NYPA through the Engineer prior to construction.
b. Starting north of the LIRR crossing, the Contractor is required to expose the FTB encased cable circuitfor38.1 m (125’)and,starting south ofthe LIRR crossing,he mustexpose76.2 m (250’). There is a yellow warning tape on top of the concrete envelope. However, at some locations, the two conduits may have been installed on top of the FTB envelope and not encased in the envelope. On reaching the top of concrete envelope, the soil on both sides of the envelope at the support locations must be removed down to the envelope bottom and the FTB removed from
around the pipes/conduits in the same area to permit installation of the pipe/conduit support system (Paragraph 2a & 2b below).
c. On exposing the entire length of the concrete envelope, the Contractor is required to place survey marks at both ends of the concrete envelope. The Contractor will then make three measurements regarding the marks. One measurement to be made is the exact horizontal distance between the two marks. The second measurement is the length between the two marks as measured with a tape positioned directly on top of the concrete envelope. The third measurement shall be the elevations, with the vertical datum clearly defined, at both mark locations and the highest and lowest points on the exposed envelope. These measurements will be used to analyze the change in pipe stresses levels, when the pipes are lowered into their new final position in the trench. d. The Contractor shall provide surface run-off diversion to prevent surface water from entering the
excavation. 2. Pipe Support System
a. Prior to excavation below and removal of the entire FTB envelope from around the pipes and conduits, a pipe/conduit support system consisting of transverse stringers of wood or steel beams spanning the trench at right angles to the pipe system axis must be installed. The pipe/conduit supportmembersmustbe positioned atintervalsofapproximately 7 m (23’)and be capable of raising or lowering the individual pipes or conduits independently. The Contractor shall also provide additional support at each pipe or conduit joint location, if any. The cable pipe weighs approximately 102.67 kgs/m (69 lbs/ft) and the fluid return pipe weighs 34.22 kgs/m (23 lbs/ft). The fiber optic conduits are light but prone to sagging and may require additional support.
b. Chain falls or coffin hoists attached to the overhead support system and to the pipes / conduits with wide nylon slings are recommended for lowering the pipes/conduits into position after the new trench bottom has been prepared. The chain falls or coffin hoists must have sufficient capacity to support the weight of the pipes.
c. At the support locations, the Contractoristo carefully remove approximately 0.5 m (20”)ofthe FTB from around the pipes and conduits to permit installation of the nylon slings. The slings mustbewideenough and configured to preventdamage to thepipe’sprotectivecoating. 3. Gas Main Support System
a. Prior to excavation below the gas main, a support system integral with the pipe support system consisting of a longitudinal beam supported from the transverse pipe supports specified in paragraph 2.a. above must be installed.
b. Support from the longitudinal beam to the gas main shall be in accordance with the Contract Documents.
4. FTB Removal
a. With the pipes and conduits properly supported, the remainder of the FTB is to be carefully removed. Records indicate that the FTB backfill had compression strength of from 345 kPa (50
psi) minimum to 1034 kPa (150 psi) maximum. However, should the concrete have higher compression strength, Elco International Inc. has a Darda hydraulic splitter for concrete, which has been used successfully for removing concrete from around corrosion protected steel high voltage cable pipes with minimal damage to the pipe coating or pipe.
b. The Contractor will be responsible for the repair of any damage to the steel pipes, including removal and disposal of any fluid leaked from the pipes. Temporary repair clamps must be available on site in the event a leak occurs.
c. On removal of the FTB, the center portion of the trench must be excavated down to final grade and the trench bottom shall be probed and inspected by the Engineer. Any soft or loose areas shall be excavated or compacted to 95% of Standard Proctor Maximum Density.
5. Pipe Protective Coating Inspection
a. On completing all trench work but prior to lowering the pipes into their final position, the Contractor musttestthepipe’scorrosion protectivecoating using arollerspring typeholiday tester capable of producing a voltage of 10,000 –12,000 volts. The Contractor must repair all defects noted. The proposed materials for repairs and the application method must be included in theContractor’ssubmittal,forreview and approvalby NYPA.The Contractormustretestall repaired areas.
6. Pipe Lowering to Final Position
a. On completing the pipe coating inspection, the Contractor is to position sand bags directly below each steelpipeatthe pipe’sdesired elevation and spaced atintervalsofapproximately 3.0 m (10’)to preventpipe sagging.The sand bag supportsmustbehigh enough to position the pipe centersapproximately 0.3 m (12”)offthefinaltrench bottom and centered under the 8 & 5 NPS pipes,which arespaced aparton 0.3 m (12”)pipecenters.
b. In addition, the Contractor is to fabricate bend restrictors from wood sheeting and support members to be placed at each end of the section to prevent kinking the pipes as they depart from the remaining FTB enclosure. The bend restrictors must have a radius not less than 15.24 m (50’).ContractormustadviseNYPA ofthedesign proposed forreview and approvalby NYPA. c. Prior to lowering the cable pipe, the Contractor is to arrange to have the cable splices located in the manholes on either side of the construction site X-Rayed to determine the exact positioning of the splice within the joint casing. After lowering the cable pipe, the splices are again to be X-Rayed to determine whether the splices have moved within the joint casing. Details of the proposed method and procedures used to X-Ray thesplicesmustbeincluded in the Contractor’s submittal, for review and approval by NYPA. The splice manholes are located at approximately 127.1 m (417’)south ofthe LIRR tracksand 387.1 m (1,270’)north ofthe E.2nd
Street/Roslyn intersection on Roslyn Road.
d. Starting at the center of the section, the Contractor shall lower the two pipes uniformly to prevent kinking the pipes, one at a time, down onto the sand bags.
e. The Contractor shall install temporary sheeting, for the new FTB encasement envelope, on either side ofthe trench,positioned 0.3 m (12”)from thepipecentersand extending 0.76 m (30”)above the trench bottom.
f. Prior to lowering the PVC conduits, the Contractor shall inspect the manholes on either side of the construction site to make sure there is slack fiber optic cable available in the event the conduits elongate during the lowering operation. The Contractor shall lower the two conduits and position them approximately 0.15 m (6”)below the top edge ofthe sheeting and 0.1 m (4”)inside the sheeting edge. The Contractor shall place ties around the steel pipes, every 7 m (23’), extending up to the PVC conduits to prevent the conduits from floating up when the FTB envelope is installed. The conduits must also be held from above until the FTB contacts the bottom of the conduits, at which time these upper ties can be removed or left in place.
7. Fluidized Thermal Backfill (FTB) a. Installation
a.1 The FTB shall be supplied and transported in such a way as to minimize segregation and to facilitate installation. The FTB shall be installed by pouring it into the trench without causing excessive segregation or by pumping it through pipes into other inaccessible locations. b. Bleed Water
b.1 The excess water that bleeds off from the FTB shall be drained away to a sump and removed. In poor draining soils, underdrains and vacuum dewatering may be used. Trapped air or bleed water shall be removed, to the Inspector's satisfaction, which may be caused by one or more elevation "crowns" in the profile.
c. Forming
c.1 If the cable trenches are shored, the shoring shall be lifted while the poured FTB is still in a fluid state.
d. Backfilling
d.1 Natural or granular backfills shall not be placed over fresh FTB until 24 hours after its placing, or at the discretion of the Inspector.
e. Winter Construction
e.1 If the FTB is to be placed in winter with temperatures at or below freezing, precautions shall be taken to protect thin lifts of backfill from freezing.
e.2 Protection of bulk pours of backfills may be omitted at the discretion of the Inspector. Any ice within the cable trench shall be removed prior to placing the FTB.
f. Compressive Strength
f.1 Unless otherwise specified by the Engineer, FTB at 28 days shall have a minimum compressive strength of 345 kPa (50 psi) and a maximum of 1034 kPa (150 psi). The compressive strength test shall conform to the ASTM test procedures C 39 for cylindrical concrete specimens, except that specimen molds shall be made of cardboard to facilitate stripping after seven days for further curing and testing.
g. Number of Test Cylinders
g.1 The number of test cylinders to be made shall be as follows:
Minimum No. of Cylinders
Test Breaks (Days) 3 7 28 Extra Until Final Determination of Mix Proportions 6 1 2 2 1 Each 50 cu meters or cu yds For each backfill
Placement: 10 to 150 cu meters or cu yds 4 1 2 1 Each 150 cu meters or cu yds 8. Trench Restoration
a. When the FTB has hardened, the Contractor shall remove the interim sheeting and the trench sheeting, if used, and back fill the trench.
b. Due to the location of the construction activities, all material removed from the trench may have to be trucked from the site. The FTB material cannot be used as backfill.
c. Excavation and backfill materials to be in accordance with the requirements of Subsection 206. All soil compaction must meet the requirements of Subsection 206-3.01. The Contractor shall be responsible for maintaining the new FTB without damage during backfill and compaction. If the FTB isdamaged due to the Contractor’soperations,the FTB shallbe repaired at no expense to the State and NYPA.
9. Drawing Review and Outage Notification
a. Shop drawingspertaining to the lowering ofNYPA’sY-49 and the temporary support of the KeySpan gas main must be submitted to NYPA / KeySpan for review and comment. NYPA / KeySpan will require one-week minimum turn around time.
b. Notification to NYPA for a required circuit outage must not be less than 30 days in advance of commencement of the work on this item. The duration of an outage shall be limited to three weeks.
10. Fiber optic cable
a. The services of a fiber optics testing and installation Contractor shall be prearranged to do testing and in the event that a new fiber optic cables need to be pulled and spliced. The Fiber optical installation Contractor shall provide certification in writing by the company producing the optical fiber cables that the Contractor is technically qualified in design, installation, servicing and testing of the required products for this project, is capable to act as a field advisor and is approved by NYPA. Prior to lowering the fiber optic cables to the final depth, the fiber optic Contractor shall test all fibers in each cable using an Optical Time Domain Reflectometer (OTDR) and Precision Loss Test Set. The Y49 fiber optic cables shall be pulled by hand from Manhole 21 and Fiber Handhole #8, once it has been verified that there is sufficient slack in the cables in these locations.
b. Once the fiber optical cables and conduits have been lowered to the final depth, the fiber optics Contractor will be required to re-test all fibers end-to-end using an OTDR and precision loss test set between East Garden City and the South Transition stations. NYPA will review the (post) to (pre) test results for any increase in db losses or stress in the fibers, and will make a determination for approval to proceed. NYPA will be provided a hard copy of all OTDR and Precision Loss Test results, and will require 2-3 business days for review.
c. In the event the fiber optic tests prove that the fibers were damaged due to the Contractor’s operations, the damaged section must be replaced at no expense to the State and NYPA. The new fiber optic cables shall be pulled by hand from Manhole 21 and Fiber Handhole #8, spliced and tested to the satisfaction of NYPA.
METHOD OF MEASUREMENT
This work shall be measured as a lump sum.
BASIS OF PAYMENT
The lump sum price bid shall include the cost of furnishing all labor, materials and equipment to complete the work except that trench and culvert excavation and, temporary and interim sheeting shall be paid under their respective items. Monthly progress payments will be made in accordance with percent work completed as determined by the Engineer.
