Opinion ID: 1318039
Heading Depth: 3
Heading Rank: 2

Heading: The Construction Techniques Relevant to the Challenged Denial

Text: Islander East proposed to employ three construction techniques in building the offshore section of the pipeline โ horizontal directional drilling, dredging, and plowing โ which the CTDEP concludes would adversely affect the existing and designated uses of the state's coastal waters, particularly as they pertain to shellfish harvesting. We briefly describe these techniques and some of the concerns identified with respect to each.
To install a pipeline running from a natural gas connection site on land in Connecticut into Long Island Sound, Islander East proposed to employ a horizontal directional drill to create a 4,200-foot tunnel underneath nearshore waters off Branford, Connecticut. See Islander East Pipeline Project, Permit Application for: 401 Water Quality Certificate (Permit Application), App. A, Maritime Pipeline Installation Methodology at 1 (Mar. 14, 2003) (Installation Methodology); see also 2006 Denial at 30 & App. B. The tunnel would start some 700 feet inland, where the drill would burrow to a depth of 110 feet below sea level. See Permit Application, Attachment C. The drill would then level off and proceed south for about 2,000 feet, after which it would drill diagonally upwards until it emerged from the Sound's seabed around milepost 10.9. See id. Once the horizontal directional drill bored a small-diameter pilot hole the length of the tunnel, Islander East proposed to enlarge that hole by a process called reaming. See Permit Application, Installation Methodology at 9-10. To effect this enlargement, a drill string would first be driven through the pilot hole to the offshore exit point. There, workers on board a barge would attach a reaming tool to the string, which would, in turn, be pulled back through the tunnel toward the drilling rig on shore. On its way, the reaming tool would cut rock and soil until the tunnel was enlarged to a diameter of 36 inches. See id. at 10. At that point, a mile-long segment of pipe would be pulled into place near the exit hole, then pulled back through the tunnel toward the drilling rig, thereby installing that underground segment of pipeline. See id. at 1, 10. Drilling fluid, a substance composed of 97 percent fresh water and 3 percent bentonite clay, would be continuously pumped into the borehole throughout the drilling process. See Conn. Siting Council, Finding of Facts, Dkt. No. 221 at 19 (Aug. 1, 2002); Permit Application, Installation Methodology at 7. This fluid would travel from equipment on the surface, through the inside of the drill pipe, out the end of the pipe, and back to the surface along the space between the drill pipe and the interior wall of the tunnel. The circulation of drilling fluid would both supply hydraulic power to the drill bit and transport soil and rock cuttings from the drill bit to the surface. See Permit Application, Installation Methodology at 7, 9. Islander East proposed to recapture, filter, and recycle most, but not all, of the drilling fluid. See id. at 7. Based on Islander East's estimates, the FERC concluded that, when the drill exited the seabed at milepost 10.9, approximately 455 barrels of drilling fluid would necessarily be released from the borehole onto the sea floor, covering an area approximately 444 feet in diameter to a depth of 5 millimeters. See FEIS 3-53. In addition to this planned release, the CTDEP identified a risk that drilling fluid could escape into Sound waters through geologic fissures in the bedrock, an unplanned release called a frac-out. See 2006 Denial at 60 (citing FEIS 3-54).
To install the next section of pipeline from milepost 10.9 to milepost 12, an area of shallow waters between 13 and 20 feet deep, Islander East proposed to dredge a v-shaped trench 5 feet into the seabed. See 2006 Denial at 32-33. To accommodate the pipeline's transition from tunnel to trench, Islander East would also dredge an acre-sized exit pit at milepost 10.9 approximately 18 feet deep, 130 feet wide, and 301 feet long. See FEIS 3-53; 2006 Denial at 32. To create this exit pit and trench, Islander East would remove approximately 24,000 cubic yards of sediment from approximately 5.5 acres of seabed. See Islander East Pipeline Project, Offshore Dredge Disposal Permit Amendment at 2 (July 29, 2003). Although Islander East originally proposed that, after installation of the pipeline into the trench, it would backfill the dredged areas with the removed sediment, in response to sedimentation concerns [6] identified by the CTDEP about that process, Islander East modified its proposal to provide for most of the dredged materials, or spoil, to be placed on barges for open water disposal. See id. at 6-10. Islander East would then refill the trench and exit pit with an engineered backfill composed of small non-native rocks and sand. This backfill would be deposited into the trench with a tremie tube, a specialized funnel designed to channel the backfill directly into the trench. See 2006 Denial at 36-37 (citing Haley & Aldrich, Inc., Report on Engineered Backfill Study (May 21, 2003)).
To complete pipeline installation in waters beyond milepost 12, Islander East proposed to continue excavation of the 5-foot-deep trench using a subsea plow, supplemented with hand-excavation by divers in certain areas. See id. at 35; Permit Application, Installation Methodology at 1. Plowing would require a barge to pass over the pipeline route three times: (1) to lay the pipe, (2) to pull a post-lay plow, and (3) to pull a backfill plow. See Permit Application, Installation Methodology at 1, 5-6. At the first step, crew on the barge would weld pipe pieces together to set onto the sea floor. As each length of pipe was so laid, the barge would move ahead approximately forty feet where the welding and laying process would begin anew. See id. at 2-3. At the second step, a barge would make another pass over each area, this time to lower a post-lay plow over the pipeline that had been laid on the sea floor. This plow would hydraulically close to encapsulate the pipe, at which point the barge would move forward, excavating a trench into which the pipe could be released when the plow was reopened. See id. at 5. At the third step, a barge equipped with a backfill plow would fill in the trench with dredged materials. See id. at 6. In each of these three passes, a barge would likely use an anchor-mooring system to move the vessel along the pipeline path, pulling in bow anchor lines and releasing stern anchor lines. See id. at 2, 5. Anchor-handling tugboats would move the bow anchors forward and pick up the stern anchors. See id. at 5. Each time anchors were thus set, they would necessarily strike the sea floor, dispersing sediment and leaving a depression several feet deep over areas of roughly 200 square feet per strike. See 2006 Denial at 41 (citing TRC Envtl. Corp., Impacts Analysis Report at 30 (Feb. 12, 2002)); see also TRC Envtl. Corp., Impacts Analysis Report ง 3.1.3 (May 2003) (updated version of 2002 Report) (estimating that [t]he total area impacted by the anchor drops from the plowing operations would be about 7.3 acres). Meanwhile, the cables attaching the anchors to a barge would drag across the sea floor as the barge moved, resulting in cable sweep, causing shallow depressions in the seabed and further dispersing sediment. 2006 Denial at 40-43 & n. 60 (citing, inter alia, TRC Envtl. Corp., Impacts Analysis Report 28, 30 (Feb. 12, 2002)).