Biological Fact Sheet - Cooling Water Intake Structure Bureau of Habitat, Steam Electric Unit

Transcription

1 Biological Fact Sheet - Cooling Water Intake Structure Bureau of Habitat, Steam Electric Unit Name of Facility: Arthur Kill Generating Station Owner/Operator: Arthur Kill Power, LLC SPDES #: NY Location: Arthur Kill Waterway Richmond County 1. Description of Facility The Arthur Kill Generating Station is an 810 megawatt oil and gas fired facility located on the east bank of the Arthur Kill, a tidal straight connecting Newark Bay and Raritan Bay. The facility withdraws, through a shoreline intake, a maximum of 713 million gallons per day of water in their once-through cooling system. The station consists of two units. Unit 20 began operation in 1959, and unit 30 began service in Each unit contains four dual flow traveling intake screens, having 1/8 x 1/8 inch screen mesh. Cooling water is returned to the Arthur Kill waterway through an approximate 900 foot long canal at a point about 525 feet south of the plant. Unit 20 has a maximum delta T of 13.6 degrees F and unit 30, a maximum of 21.3 degrees F. 2. Ecological Resource The Arthur Kill is part of the Hudson-Raritan estuary system, extending approximately 170 miles from the dam at Troy, NY to Sandy Hook, NJ. The estuary system connects to the coastal marine waters of the New York Bight, between Sandy Hook, NJ and Rockaway Point, NY, and to the western end of the Long Island Sound through the East River. More than 140 species of fish have been reported from the Hudson-Raritan system, representing marine, estuarine, freshwater and diadromous fish, as well as species adapted to northern and southern climates. The Arthur Kill is a tidal strait and not a river. Several small tidal creeks and the Fresh Kills marsh provide nutrients as well as nursery areas for many estuarine species. The Arthur Kill is a major waterway for commercial boat traffic, having a 35 foot deep navigation channel along its entire length. Near shore waters, particularly along the eastern side, are shallow with broad mud flats at low tide. The vertical tidal range is 4.7 feet, and channel currents approach 1.7 feet per second. Numerous industries are located along the banks of the Arthur Kill, and the waterway has a history of environmental degradation. In the 1970s dissolved oxygen levels had declined to near 0 mg/l during summer months. Since that time, water quality has improved throughout New York Harbor. During the biological studies conducted at the station in the early 1990's, summer dissolved oxygen remained above 3.8 mg/l, and more than 70 species of fish, mostly marine in origin, were collected in impingement and entrainment samples. Under a 1992 consent order, several biological studies were conducted at the station to determine 1

2 the extent of impact from operation of the cooling water intake system and what could constitute best technology available (BTA) to minimize that impact. An impingement and entrainment abundance study was conducted between September 1991 and September Approximately 9.7 million fish were impinged: primarily bay anchovy, Atlantic herring and blueback herring. Approximately 16.4 million eggs, larvae and young-of-the-year fish were entrained: primarily bay anchovy, goby, northern pipefish and blueback herring. Impingement survival studies were conducted between February 1994 and July 1995 from standard intake screens and from two screens modified with biologically protective mechanisms (specially designed fish buckets, smooth screen mesh, low pressure spray wash and structures to redistribute flow more evenly across the screen face). The studies found that the modified screens substantially improved impingement survival: from 15.2% off standard dual flow screens to 78.9% off modified screens of similar mesh size. Other consent order studies included thermal tolerance assessments of impinged fish, and a study to site a fish return system. A detailed site investigation of an aquatic filter barrier, the Gunderboom MLES, occurred between 2002 and Due to problems with biofouling and maintenance of adequate through fabric flow rates, anchoring in soft sediments, and the barrier s likely encroachment on tidal wetlands nearby, it was determined that this technology is not suitable for the Arthur Kill Station Site, and further development will not be required here. Most recently, an impingement and entrainment study was conducted at the station from April 2006 to April Eighty four taxa of fish were collected from the station s intake screens. Approximately 7.38 million fish were impinged at the full calculated baseline flow. Bay anchovy (76%), Atlantic menhaden (4%), Atlantic croaker (4%) and Atlantic silverside (1.4%) were the predominant species impinged. An estimated 2.6 billion eggs and larvae were entrained at the full calculated baseline flow. Bay anchovy accounted for some 90% of entrainment. Goby, cunner and Atlantic croaker, accounting for a combined 8% of total entrainment were next most abundant. 3. Alternatives Evaluated A Request for Information (RFI), as part of the SPDES permit renewal process, was sent to the applicant in June The RFI included a requirement to submit a Proposal for Information Collection containing a description of the proposed and/or implemented technologies and/or operational measures to be evaluated in a Design and Construction Technology Plan (DCTP). The New York State Department of Environmental Conservation (Department) required that the following technologies and operational measures be evaluated in the applicants DCTP, which was approved in October 2007: Closed Cycle Cooling Modified Ristroph Traveling Screens (with fine mesh) and Fish Return System Cylindrical Wedge Wire Screens Aquatic Filter Barrier Fish Net Barrier Submerged Off Shore Velocity Cap 2

3 Variable Speed Cooling Water Pumps Shutting Down Circulating Water Pumps 4. Discussion of Best Technology Available In accordance with 6NYCRR Intake structures and Section 316(b) of the federal Clean Water Act, the location, design, construction, and capacity of cooling water intake structures must reflect the "best technology available" (BTA) for minimizing adverse environmental impact. The identification of BTA is a technology driven determination, however, the final decision may also consider cost in determining whether the technology can be reasonably borne by the facility and whether one technology or suite of technologies and/or operational measures is more cost effective than another providing essentially the same resource protection (Riverkeeper II, 2007, Riverkeeper I, 2004). A. Location The Submerged Off Shore Velocity Cap would relocate the intake to within the Arthur Kill shipping channel and is considered to be a navigation hazard, and therefore not feasible. All other alternatives evaluated withdraw cooling from the existing shoreline intake, therefore location is not considered further. B. Design Alternatives such as modified Ristroph screens, wedge wire screens, aquatic filter barrier, and the fish net barrier require redesign of the station s intake. All alternatives except Ristroph screens are not considered to be feasible due to problems such as biological fouling, unsuitable substrates for anchoring, lack of sufficient currents for cleaning and shallow depth of the waterway. C. Construction Construction impacts are considered to be major for closed cycle cooling, and wedge wire screen installation. Siting cooling towers will require filling a major part of the fresh water wetlands located north of the station, and is not considered feasible at this site. Installation of wedge wire screens would require significant dredging in front of the station to achieve sufficient depth, and is part of the reason why this alternative is not considered to be feasible. For other alternatives, construction is either confined within the station, or impacts are minor and temporary in nature. D. Capacity Alternatives such as closed cycle cooling, variable speed pumps and circulating water pump shutdown affect capacity. Closed cycle cooling achieves the largest reduction in cooling water use (approximately 95%), but is not feasible due to large construction impacts. Use of variable speed pumps, and shutting off one circulating pump when the Unit is operating at loads of less than 50% will achieve equivalent cooling water reductions. Pump shutdowns is the less costly of the two alternatives. Other alternatives do not affect capacity of the station. 3

4 5. Determination of Best Technology Available After evaluating all of the available alternatives, the Department has determined that the use of Ristroph modified dual flow traveling intake screens, including the use of fine mesh (1.0 mm or less) panels on a seasonal basis, represents the best technology available for minimizing adverse environmental impacts from the cooling water intake structure. These technologies have been determined to be a cost-effective way to meet the requirements of and 316(b) CWA and can be reasonably borne by the facility. SPDES permit conditions implementing BTA for the Arthur Kill facility are listed below. 1. By EDM + 3 months, the applicant shall submit an approvable plan to replace all standard dual flow intake screens at Units 20 and 30 with Ristroph modified dual flow intake screens, and a dedicated fish return system to safely transport impinged fish back to the Arthur Kill waterway. The plan shall contain drawings and descriptions of all work to be done, a schedule for installation of the screens and for testing the use of fine mesh (1.0 mm or finer) panels to minimize entrainment of fish eggs and larvae. By EDM + 4 years, intake screen installation shall be completed. Upon Department approval, the plan and schedule shall become enforceable conditions of this permit. 2. By March 1 of each year, the applicant shall submit a report showing, in tabular fashion, the average monthly volume of cooling water used by each unit for the preceding year. 3. If, upon completion of Verification Monitoring Studies the Department determines that the performance standards contained No. C.3 have not been met, then within 3 months of such notification the applicant shall submit an approvable plan to reduce cooling water use at the Arthur Kill Station. The plan may include, but may not be limited to the shutting down of one cooling water pump when that unit is operating at reduced electrical generation (e.g. loads less than 50% design capacity). Upon Department approval, the plan and schedule shall become enforceable conditions of this permit. In keeping with the Department s established, environmentally-protective BTA requirements for existing facilities with cooling water intake structures, an 80% reduction in impingement mortality and 70% reduction in entrainment, from full flow baseline level, are the minimum impact reductions the Department expects to achieve from implementation of these permit conditions. 6. Monitoring Requirements In accordance with Biological Monitoring Requirement C.(4.) of the attached permit, the permittee must submit to the NYS DEC Steam Electric Unit, for Department approval, a Verification Monitoring Plan. This plan is designed to confirm that the reductions in impingement and entrainment required by this permit are being achieved. At a minimum, the plan must include two years of full scale impingement and entrainment studies during this permit 4

5 term. These studies must quantify by species the numbers of fish and shellfish impinged and entrained at the facility under both estimated full flow baseline conditions and actual operating conditions during the two year study period. The studies must also evaluate the effectiveness of technologies and operational measures implemented to reduce fish and shellfish mortality. 7. Legal Requirements The requirements for the cooling water intake structure in this State Pollutant Discharge Elimination System permit are consistent with the policies and requirements embodied in the New York State Environmental Conservation Law, in particular ; ; b., c.; ; b., c., I., s. and t.; ; ; ; ; ; ; , 4.g.; and the rules thereunder, specifically 6NYCRR In addition, the requirements are consistent with the Clean Water Act, in particular section 316(b). 9. Summary of Changes Table 2. Deletions (Former Permit Conditions) Permit Condition Additional Requirement C.1 Additional Requirement C.2 Additional Requirement C.3 Reason for Deletion Addition. Requirement to submit an impingement mortality and entrainment characterization study. Condition Complied with.. Addition. Requirement to submit a design and construction technology plan to review BTA alternatives. Condition Complied with.. Addition. Requirement to submit BTA measures, for Department approval, to meet requirements of 6 NYCRR Part

6 Additional Requirement No. 9 Condition Complied with.. Condition was revised and renumbered as General Requirement No. C.11 Table 3. Additions/Change (New Permit Conditions) Permit Condition Reason for Addition/Change Additional Requirement - New No. C.1 Technology Installation and Operation Plan Additional Requirement - New No. C.3 Additional Requirement - New No. C.4 Listing of conditions found in section 5, that the Department has determined will constitute BTA for the Arthur Kill Generating Station. Requires installation of BTA within 5 year period of permit and establishes performance standards to be met of 70% reduction in entrainment and 80% reduction in impingement mortality. Requires a contingency plan to be submitted that will reduce cooling water use in the event that the verification monitoring studies show the performance standards are not being met by the BTA technologies installed under Additional Condition No References Con. Ed Arthur Kill Generating Station. Diagnostic Study and Post-Impingement Viability Substudy Report. Prepared by Consolidated Edison Company of New York, Inc. Pursuant to the December 23, 1993 Order On Consent in DEC file No. R January 31, Lawler, Matusky and Skelly Engineers Arthur Kill Impingement and Entrainment Report, September September Prepared for the Consolidated Edison Company of New York. February 1993; Revised August NRG Request For Information. Arthur Kill Generating Station. SPDES No. NY Arthur Kill Power, LLC. Staten Island, New York November Shaw Environmental, Inc. and Normandeau Associates, Inc Cooling Water Intake Structure Design & Construction Technology Review. NRG Arthur Kill Power LLC. Arthur Kill Generating Station. Prepared for NRG by Shaw Environmental, Inc. And Normandeau Associates, Inc. August 31,