Section 5.0 Environmental and Socioeconomic Consequences
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U.S. Department of the Interior Section 5.0 MM S Minerals Management Service Environmental and Socioeconomic Consequences 5.0 ENVIRONMENTAL AND SOCIOECONOMIC CONSEQUENCES 5.1 IMPACT-PRODUCING FACTORS – NORMAL CONDITIONS The identification and description of activities, equipment, materials, and processes that have the potential to create impacts on natural and human resources in areas proposed for use by the proposed action has been divided into two main categories, those items occurring under normal conditions, and under non-routine conditions. Normal conditions are discussed below, which are then followed by the non-routine conditions (Section 5.2). These factors are then used, as appropriate, in characterizing resource impacts in Sections 5.3 and 5.4, as well as to some extent in Section 6.0. It is important to note that these factors need to be considered within the larger context of other sources of the same or similar impact-producing factors that have occurred in the recent past, do currently occur, or could reasonably be expected to occur in the near future, within the site of the proposed action (refer to Table 5.1.1-1 for a summary of Impact Producing Factors). 5.1.1 Maintenance or Construction Vessels and Crew boats Impacts associated with vessels to be used during construction, operation, and decommissioning of the proposed action, many of which are common to most commercial vessels operating in Nantucket Sound, can be placed into three timeframes during transit, while on station, and while at staging areas. The characteristics of how and what impact factors are associated with these three timeframes are described in the following subsections. 5.1.1.1 Vessel Activity (in Transit, on Station, and at Staging or Maintenance Base) The most probable scenario is that the majority of material and equipment would be staged onshore, most likely at existing port facilities in Quonset, Rhode Island, and then loaded onto various vessels for transportation to the offshore site, and ultimately installation. Construction personnel would be ferried by boat and/or helicopter depending upon weather conditions and other factors. Once loaded, if traveling from Quonset, the vessels would pass through Narragansett Bay to Rhode Island Sound then to Vineyard Sound, and then North of Martha’s Vineyard to the Main Channel, a distance of about 63.3 miles (101.9 km). While these vessels are in transit, certain aspects of their operation have the potential to generate a number of impacts on marine resources. During construction and decommissioning, the majority of vessel berthing and loading would likely occur at Quonset. Smaller supply or crew boats may also operate out of Cape Cod ports, such as Falmouth and New Bedford. During the proposed action operation phase, maintenance vessels would operate out of Hyannis or similar Cape Cod port, under normal conditions. These ports have adequate facilities for berthing and loading of the maintenance vessel(s). The impacts from all vessel activity are described below. 5.1.1.1.1 Sumps, Ballast, and Bilge Discharges Bilge water is water that collects in the lower part of a ship. The bilge water is often contaminated by oil that leaks from the machinery within the vessel. The discharge of any oil or oily mixtures is prohibited under 33 CFR 151.10; however, discharges may occur in waters greater than 13.8 miles (22.2 km) offshore if the oil concentration is less than 100 parts per million (ppm). Discharges may occur within 13.8 miles (22.2 km) if the concentration is less than 15 ppm. Ballast water is used to maintain stability and trim of the vessel and may be withdrawn from coastal or marine waters through structures in the hulls of ships called sea chests. Generally, the ballast water is pumped into and out of separate compartments or tanks depending upon the requirements to maintain proper vessel stability and trim as cargo is unloaded. Ballast compartments are not usually contaminated with oil as they are isolated from machinery and engines; however, the same discharge criteria apply as for bilge water (33 CFR 151.10). Cape Wind Energy Project 5-1 January 2009 Final EIS U.S. Department of the Interior Section 5.0 MM S Minerals Management Service Environmental and Socioeconomic Consequences In other instances, vessels that arrive empty or load and unload in different locations associated with the proposed action would also result in the discharge of ballast as cargo is taken on board. For example, a barge that is loaded with construction materials and equipment at the onshore staging area would have minimal ballast. After transit to the site of the proposed action and offloading materials as the WTGs are constructed, these vessels may take on ballast water to maintain trim and stability for the transit back to shore for re-loading. Ballast water withdrawals result in entrainment of planktonic marine life and then the discharge of these organisms at a different location. Withdrawal impacts are described further in Section 5.1.1.1.5. In addition to water quality concerns associated with ballast water discharge, an additional potential impact is the introduction of invasive species into local waters, from vessels coming from over seas or from other U.S. ports. Impact characteristics that result from discharge from vessels described above are also similar to vessels in transit, except for the fact that vessels on station are discharging at a relatively constant location. Whereas vessels in transit have the advantage of a moving discharge resulting in greater dilution and dispersion of the discharged water, vessels on station rely on local currents and passive dispersion mechanisms to dilute the waste water within the receiving water. Should these discharges have characteristics that adversely affect water quality or marine organisms, such as low dissolved oxygen (DO) or pollutants, the severity of the localized impact may be greater than for a vessel in transit. All vessels for the proposed action would comply with applicable mandatory ballast water management practices established by the USCG in order to minimize the inadvertent transport of invasive species as well as the potential for adversely impacting water quality. 5.1.1.1.2 Deck Drainage Deck drainage includes all wastewater resulting from deck washings, rainwater, and runoff from curbs, gutters, and drains including drip pans and work areas. The USEPA general guidelines for deck drainage require that no free oil be discharged, as determined by visual sheen. The quantities of deck drainage vary greatly depending on the size and location of the equipment. Large vessels employed during construction, operation, and decommissioning, particularly those with machinery operating on deck, such as cranes or generators, should be designed to avoid oily deck drainage discharge to the ocean. 5.1.1.1.3 Greywater Discharges On board vessels, domestic wastewater originating from sinks, showers, laundries, and galleys is referred to as greywater. Sanitary wastewater originates from toilets and is referred to as blackwater, which is discussed in Section 5.1.1.1.4. For greywater, no solids or foam may be discharged. In general, operation of large vessels with crew quarters and full live-on-board capabilities would result in the generation of 50 to 100 gallons/person/day (189 to 378 liters/person/day) of greywater. Given the currents and volume of water in an open water setting, it is assumed that where allowed, discharges of greywater are rapidly diluted and dispersed. State and local governments regulate greywater from vessels when operating near shore. Unlike vessels in transit, wastewater discharges from vessels on station would occur more like a point source discharge, with less potential for dispersal and dilution. In these instances, local currents and water depth, would affect the dispersal and dilution factors, and the concentration of a wastewater plume would be higher in the localized area around the point of discharge compared to a vessel in transit. However, again, Horseshoe Shoal is essentially in an open ocean setting and greywater discharges are anticipated to rapidly dilute and disperse. Discharge of greywater would not occur into the harbor while vessels are berthed. Instead, wastewater would either be held until offshore disposal can occur or would be pumped onshore for proper disposal. All vessel waste would be offloaded, stored and disposed of in accordance with all applicable local, state and Federal regulations. Cape Wind Energy Project 5-2 January 2009 Final EIS U.S. Department of the Interior Section 5.0 MM S Minerals Management Service Environmental and Socioeconomic Consequences 5.1.1.1.4 Blackwater Discharges In sanitary waste, floating solids are prohibited. Facilities with 10 or more people must meet and maintain the requirement of total residual chlorine greater than 1 mg/L. In general, operation of large vessels would result in the generation and discharge of 35 gallons/person/day (132.5 liters/person/day) of treated sanitary wastes. All vessels with toilet facilities must have a Marine Sanitation Device (MSD) that complies with 40 CFR 140 and 33 CFR 149. Vessels complying with 33 CFR 159 are not subject to State and local MSD requirements. Type I and II MSDs are systems that mechanically chop up the sewage, chemically treat it, and discharge it through a screen. These MSD systems can not be used, however, in coastal waters that are designated as No Discharge Areas (NDAs). The NDAs are areas where discharge of any treated or untreated sewage is prohibited. There are currently eight NDAs in Massachusetts: the coastal waters of Plymouth, Kingston, and Duxbury, all of Buzzards Bay, Waquoit Bay in Falmouth, the coastal waters of Harwich, Three Bays/Centerville Harbor in Barnstable, Stage Harbor in Chatham, Wellfleet Harbor, and the coastal waters of Nantucket from Muskeget Island to Great Point, including Nantucket Harbor.