1 Site Visit Report Mercer Generating Station Lamberton Road Hamilton Township, NJ 08611 May 26 , 2010 1.0 Background and Objectives The Environmental Protection Agency (EPA) is in the process of developing 316(b) cooling water intake structure requirements that reflect the best technology available (BTA) for minimizing adverse environmental impact for all existing power plants and manufacturing facilities. As part of this process, EPA staff is visiting electric generators and manufacturers to better underst and the cooling water intake structure (CWI S) technologies in use at facilities, including the site

specific characteristics of each facility and how these affect the selection and performance of CWI S technologies. EPA is also visiting facilities to bette r understand cooling water use and specific issues or technologies that can affect 316(b) compliance. Mercer was selected for a site visit due to its proximity to EPA Headquarters and its location on a large tidal ly influenced freshwater river
. 1 2.0 Facility Description Mercer is located on a 115 acre site outside of Trenton, along the Delaware River, 2 and began operations in 1960. The facility is owned by PSEG and employ s approximately 125 people. The facility ’s NPDES permit (NJ0004995) is due to expire o n October 31, 2011. 3.0 Electricity Generation and Transmission Mercer has two coal

- fired generating units, each with a generating capacity of 300 MW (600 MW total)
. The facilit y ty picall y uses eastern bituminous coal from West Virginia. 3 The coal (deliver ed b y barge) is a premium grade with low sulfur content. Mercer is a load

- following plant, with a capacit y factor in recent years of approximately

50
- 70%. The facility

has routine maintenance outages approximately every 18 months. Unit 3 is an old 8

- tur

bine expander turbine generating unit (125 MW total) that is rarel y operated and will be decommissioned in 2015.

1 EPA w as unable to provide a copy of this report to the facility for review prior to publication. 2 Mercer is located in the freshwater portion of the Delaware River, but does experience tidal surges of up to 7 feet. Approximately 3 miles downriver, the Delaware is generally considered to be tidal/brackish. 3 The facility has 3 pulverizers to provide fuel to the generating units. These units can also burn natural gas.2

4.0 Cooling Water System and Intake Structure Mercer uses a once
- through cooling s ys tem and operates a shoreline CWI S. The intake structure is comprised of a trash rack/ice barrier followed by coarse mesh traveling screens (1/2 b y 1/4 inch mesh). There are 4 screens, each with a single fixed speed circulating pump and a service water pump, with a total design intake flow of 610 million gallons p er day (mgd). 4 The design through

- screen velocity is approximately 1.5 feet per second (fps). The facility is permitted to use chlorine as a biocide for up to three 20 minute cycles per day
. The facility is also capable of redirecting heated effluent to the CWI S in the winter to prevent ice formation. As part of the requirements in their current NPDES permit, Mercer will be installing new Ristroph screens with a new directional (i.e., will discharge fish in the direction of the tidal current) fish retur n and dual pressure spray wash next ye ar. The screens will be continuously rotated from May

to October. The new screens will cost approximately $8 million. PSEG selected the Ristroph screens over other designs due to the familiarity from using them at o ther sites and known performance. Mercer will be required to conduct 2 y ears of verification monitoring following the installation of the new screens. 5.0 Impingement and Entrainment Information The facility

conducted extensive impingement and entrainment s tudies in the 1990s (one in 1991

- 1992 and another in 1998

- 1999) and did not find significant impingement, even during the large shad runs each spring. 6.0 Cooling Tower Feasibility The facility

has not extensively

studied a potential retrofit to closed

- cycle cooling. Facilit y representatives noted significant economic challenges (see Section 14.0), as well as space constraints; the facility ’s recently constructed air emissions controls occup y much of the space near the facility. Facilit y representatives als o noted a nearb y highway that could be affected. See Section 12.0 below for information on other potentially available space. Mercer has a wastewater treatment facility onsite and facility

representatives assumed that it would be capable of handling addi tional flow from cooling tower blowdown if the site were required to retrofit to closed

- cycle cooling. 7.0 Debris Handling Mercer does not have significant problems with trash or debris. Episodic debris events occur in spring, when accumulated wood y debris is flushed into the river.

4 Each circulating pump is rated at 105,000 gpm, while each service water pump has a capacity of 875 gpm.3

8.0 Repowering/Future Uses Facilit y representatives stated that there are no plans to expand the facility; at present, Mercer provides PSEG with valuable fuel diversity in its generating fleet. 9.0 Cooling Ponds There are no active cooling ponds on site. Two ash ponds are no longer in service; see Section 12.0. 10.0 Ownership Mercer is owned b y PSE G , an investor

- owned company
. PSEG has fossil plants in New Jersey , Connecticut, New York and Texas, plus nuclear plants in New Jersey
. 11.0 31 6(a) Mercer is subject to thermal discharge limits (discharge temperature, total heat load, and delta T) and has a 316(a) variance that was developed in the 1990s. 12.0 Ash Handling Bottom ash is used for roofing and other products, while fly ash is also use d for beneficial uses. Mercer previousl y operated two ash ponds just northeast of the generating units , but decommissioned these ponds in the 1990s. 13.0 Air Emissions Controls Mercer is constructing a dry scrubber for each generating unit to address SOx. T hese units will become operational in late 2010. The facility also installed electrostatic precipitators in the 1990s to collect dust and particulate matter. In 2004, they

added an SCR to address NOx emissions. By adding each of these control technologi es, the facility has greater flexibility

in the t ypes of coal that it can use. Facilit y representatives noted that PSEG is closing 2000 MW of generating capacity

as a result of compliance with air regulations. They added that new units are being added at some facilities, but that the company will not recover all of the lost capacity
. 14.0 Additional Information In response to the now

- suspended 2004 Phase II rule, facility representatives stated that Mercer was likely to pursue the cost

- benefit test, given th e low impingement and entrainment rates at the site. They noted that NJDEP was likely4 to be supportive of this, as they generally consider Mercer to be a site with low biological impacts. Facilit y representatives stated that the revised rule should contain a site

- specific option, as cooling towers are not a sensible choice for facilities such as Mercer. They believe that a cost - benefit test is the most direct approach, but other options (such as pre

- approved technologies for certain categories of facility) may also be available. Facility

representatives note that PSEG operates a number of facilities that are onl y marginally profitable; a rule requiring closed

- cycle cooling could have a significant effect. Merryll Reservoir is a large off

- river reservoir upstream of the site that was constructed b y power plants in the area to provide supplemental water supplies in times of extreme drought. PSEG deploy ed a Gunderboom at another facility (Bethlehem Energy

Center) and experienced significant problems. The first

- of
- its

- kind fixed panel barrier failed each season it was deployed for a variet y of reasons. Bergen is a sister station to Mercer and recentl y repowered to combined cycle with cooling towers (with plume abatement); a nearb y WWTP supplies the makeup water for the towers.

Attachments Attachment A List of Attendees Attachment B Aerial Photos Attachment C Site Visit Photos5

Attachment A -- List of Attendees Paul Shriner, EPA Headquarters Erik Helm , EPA Headquarters Tom Born , EPA Headquarters S hari Goodwin, Tetra Tech Kelly Meadows, Tetra Tech Mark Strickland, PSEG Carmine DeNicola, PSEG Mark Schwartzkopf, PSEG6

Attachment C

— Site Visit Photos Please see DCNs 10

- 6558B through L accompan ying this document.