Since the pattern of future OCS development cannot be predicted with certainty, assumptions must be made to allow impact analysis to be performed. These assumptions are the basis of the scenarios developed in this impact state ment. They are not development plans or proposals but are believed to represent reasonable patterns of development which could occur as a result of this sale. This section describes these assumptions and why they have been chosen. Resources The analyses in this EIS are based on estimates of the oil and gas resources in the area being offered for lease and corresponding infrastructure scenarios developed by the Minerals Management Service (MMS) prior to the lease sale. The estimates of the oil and gas resources used in the EIS are produced by a computer model which simulates drilling of identified prospects. The probabilistic resource estimates for the outer continental shelf (PRESTO) model utilized seven variables in determining the potential oil and gas resources of the proposed sale area. These seven variables are: 1) productive area (acres), 2) pay zone thickness (feet), 3) proportion of pay in oil reservoirs, 4) oil recovery factor for oil reservoirs (barrels per acre-foot, 5) gas-oil ratio (cubic feet of associated gas per barrel), 6) gas recovery factor for gas reservoirs (thousands of cubic feet of nonassociated gas per acre-foot), and 7) condensate yeild ratio for liquids produced from gas reservoirs (barrels per million cubic feet of non-associated gas). Using these variables and a probability of whether commercial quantities of hydrocarbons exist in the area, the PRESTO model determines a cumulative probability distribution of the oil and gas resources in the proposed sale area. From this probability distribution a mean, high, and low level of oil and gas is determined. It should be remembered that conditional resource estimates have been used rather than risked estimates. Conditional estimates incorporate the assumption that recoverable hydrocarbons exist in the area, while risked estimates reflect the possibility that the area is dry. Risked resource estimates are used by industry and government analysts to assess the dollar bid value of undiscovered oil and gas in a block. However, since conditional estimates indicate the amount of resources you can expect to find if hydrocarbons are discovered, they are appropriate estimates to use when analyzing environmental impact. Therefore, this EIS is based upon conditional estimates. Transportation of Gas Pipelines have been assumed as the mode of transportation for the proposed Mid-Atlantic mean scenario gas discoveries. Alternative concepts for transporting natural gas, such as converting the natural gas offshore to methanol (petrochemical intermediate), ammonia (fertilizer), or liquified natural gas (LNG), and transporting by tanker, or using the gas to generate electricity offshore and transmitting the electricity to shore by cables, have not been assumed because of economic infeasibility and/or the fact that they are still in various stages of design and have not yet been implemented in offshore operations (Policy Planning & Evaluation, 1983). Therefore, it is assumed that gas discoveries made in the mean scenario for the proposed lease sale area will be collected by numerous small diameter gathering lines which would connect with one 36-inch trunkline assumed necessary to carry Mid-Atlantic gas production based on the estimated gas production schedules for the proposed sale area. A second 36-inch trunkline is assumed for gas produced from previously leased lands. The offshore pipeline routes selected will not necessarily be straight lines to shore. Because of the generally higher cost per mile of offshore pipeline installation versus onshore, a straight line route to the point onshore nearest to the offshore production site would be the economically preferred, however, some deviation often occurs. Therefore, the offshore pipeline routes selected for these scenarios are not always the shortest routes possible but reflect possible constraints that could increase pipeline length such as landfall restrictions (environmentally-related), land-use conflicts, and offshore geological factors. These constraints are considered by studying CZM plans, local land-use policies, and available geological information. Based on the above factors, two possible landfall sites for the gas pipelines have been selected. These two landfall sites are Monmouth County, New Jersey, and Sussex County, Delaware. The proposed landfall in Monmouth County, New Jersey, would come ashore in the general area of Sea Girt, which is already highly developed and fairly densely populated. To avoid inconveniencing the public in Sea Girt, the vicinity of a National Guard Camp located between Sea Girt Avenue and Stockton Lake could be selected as an appropriate landfall. The proposed pipeline would cross an area seaward of the National Guard Camp for a distance of two nautical miles offshore that is restricted to boat traffic because of a small arms firing range located parallel to the beach. Pipeline construction would, therefore, not create any additional navigation hazard. The pipeline would cross approximately 200 feet of beach along an existing beach access. road, which would subsequently be returned to its pre-construction appearance and use. The National Guard Camp would be crossed parallel to one of its borders. The pipeline would then cross Roberts Avenue (Highway 71), merging with an abandoned Penn Central railroad right-of-way which runs northwest to and across Allaire State Park to Interstate 195. A number of environmentally sensitive areas are avoided by this route, including commercially or recreationally valuable shellfish beds, submerged vegetation, the barrier island corridor, undeveloped dunes, and ecologically sensitive coastal wetlands. Because relatively few streets are crossed, potential inconvenience to the public, such as disrupted traffic flow, noise and dust, are minimized. (EMANCO, Inc., 1980.) From the landfall area, the pipeline is assumed to travel onshore to a gas facility assumed to be built in the Wall Township of Monmouth County. This landfall has been identified and studied as a viable choice by both industry and the State. Such a gas plant site was examined in the Monmouth County OCS Plan (Monmouth County Planning Board, 1978). The pipeline could then proceed west to join the ROW utilized by the four other gas pipelines in Mercer County. Eventually, the pipeline would be connected to one of the major gas trunklines which service the east coast. This connection most probably would take place in the Princeton Township of Mercer County. (Golden, 1980.) The pipeline with a proposed landfall in Sussex County, Delaware, most likely would come ashore in the vicinity of Bethany Beach. Once ashore, the pipeline could possibly follow an existing ROW through Kent and New Castle Counties to Chester County, Pennsylvania. Existing ROWS include U.S. Route 13 and 113, Conrail lines that run roughly parallel with Routes 13 and 113, and powerline ROWS of the Delmarva Power and Light Company. If the pipeline utilizes existing ROWs, a possible route could follow Route 26 west to either Route 113 or a Contail ROW, then north to Wilmington (Route 113 merges with Route 13 at Dover). A gas facility could be located in New Castle County in the greater Wilmington area, perhaps adjacent to a chemical plant so as to reduce transportation costs for liquids such as ethane. From this plant, the pipeline route could proceed north into Pennsylvania, looping into an existing Transco ROW to a junction with an interstate line in Chester County. Specific onshore pipeline routes have not been identified. While the impacts of siting certain facilities, such as gas facilities and operations support bases, can be fairly assessed through a county or area-specific identification and analysis, it is believed that the identification of a particular onshore route and specific rights-of-way, even for the sake of impact assessment, is inappropriate at this time. Since the impacts of an onshore pipeline are generally minor in nature, limited in scope, and very specific to the route selected, addressing the impacts of one particular route at this early stage would lead to a very limited, inapplicable assessment. While, for example, industry has certain siting criteria and preferences, actual pipeline routing will involve the balancing of these as well as certain environmental, technical, legal, economic, and social considerations. These factors will also influence the mitigating measures employed and the timing of construction activities. Preferences of all levels of government will have to be considered (See "Land Use and Coastal Management," Section III.D.4). Therefore, based on the limited, isolated impacts associated with onshore pipelines, and tremendous uncertainty associated with onshore routing decisions, a route between landfall site and gas facility has not been identified. Gas Processing and Treatment Plants Because of the present lack of natural gas processing and treatment plants in the Mid-Atlantic Region, it has been assumed that gas plants would have to be constructed. These plants are assumed to accommodate gas from prior sales as well as from proposed Sale No. 111. Two jurisdictions have been identified as possible locations for the gas plants. These are New Castle County, Delaware or Monmouth County, New Jersey. These areas were selected based on their positive attitudes towards development, suitable industrially zoned acreages, and proximities to gas infrastructure or major consumption centers. The nature of these gas plants, as with any gas plant, will depend on the composition of the gas that must be posessed. Dry, low sulfur gas would need virtually no dehydration, processing, and treatment prior to entrance into the existing transmission system. Wet, high sulfur gas may require extensive dehydration, processing, and treatment. Although no information on these characteristics is currently available, it has been assumed, for the sake of impact analysis, that some degree of dehydration, processing, and treatment will be necessary before any of the OCS gas production may enter the existing transmission system and plants employed in the scenario have been identified accordingly. Transportation Oil Offshore oil may be transported to shore via pipelines or tankers. The factors influencing the choice between the different modes of transportation include the size and composition of the offshore field; the field's distance from shore; local weather conditions; oceanographic conditions; and the availability of refineries in the frontier region (Brower, 1981; Policy, Planning, and Evaluation, 1983.) All oil produced under Sale No. 111 and currently leased lands would be collected by numerous gathering lines and connected to two single point moorings located in shallow waters. From here the oil would be transported to shore by tankers. It is estimated that approximately 55 tanker trips (50,000 DWT) will be needed to transport the peak year of oil production. This oil is expected, for the most part, to replace imported oil over the long term. Other Infrastructure Compressor Stations Because of the long distances the pipelines must span, and the assumed gas characteristics, it has been assumed that compressor stations could be necessary to ensure smooth movement within the pipeline. It has been assumed that these compressor stations would be located along the pipeline route at a depth suitable for a conventional bottom-founded platform (see section on resources and production systems). One onshore compressor station is also assumed to be located somewhere between the Bethany Beach landfall and the gas processing facility near Wilmington. Pipecoating Yards Though coating of the pipe could occur at a variety of Mid-Atlantic coastal locations, the expected quantity of work generated by proposed Sale No. 111, as well as the ability of existing yards to meet the required delivery schedule of the oil and gas industry assumed for this sale, imply that pipe coating activity could be accommodated by existing yards. Numerous suitable facilities are located in the Gulf of Mexico Region. From there, the coated pipe would be transported to either the operations support base or the offshore site. Platform Fabrication It has been assumed that platform fabrication and subsea complex construction for proposed Sale No. 111 would occur at existing yards in the Gulf of Mexico Region or Canada. From here, they would be shipped to the Mid-Atlantic offshore area. This assumption was based on 1) the fact that there are no existing platform fabrication yards of subsea complex construction areas on the East Coast, nor any active proposals to set up either, and 2) the MMS estimates of the schedule of production expected and cost required imply that it may be more feasible to ship these platforms and subseas from existing yards than set up new ones. The establishment of new construction facilities involves the consideration of many factors such as overall worldwide demand for platforms and subsea complexes, existing capacities for construction, competitive position of individual companies, and the pace of OCS development on the Atlantic coast. |