1 Site Visit Report

Possum Point Power Station

19000 Possum Point Road Dumfries, VA 22026 March 10, 2009

1.0 Background and Objectives

The Environmental Protection Agency (EPA) is in the process of developing 316(b) cooling water intake structure requi rements 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 generato rs and manufacturers to better understand the cooling water intake structure (CWIS) technologies in use at facilities, including the sitespecific characteristics of each facility and how these affect the selection and performance of CWIS technologies. EPA is also visiting f acilities to better understand cooling water use and specific is sues or technologies that can affect 316(b) compliance. Possum Point Power St ation was selected for a site visit due to its proximity to EPA Headquarters, its use of combined cycle, and its use of partial closed-cycle cooling.

2.0 Facility Description

Possum Point is located on a 640 acre site in Dumfries, Virginia. Most of the developed area of the site is on a peni nsula at the confluence of the Potomac River (a tidal river) and Quantico Creek. The facility began operations in 1948 and employs roughly 110 people.

Possum Point is owned and operated by Do minion Virginia Power (Dominion). The facility’s NPDES permit (VA00 02071) is due to expire May 31, 2009. 1

3.0 Electricity Generation and Transmission

Possum Point consists of four active ge nerating units with a total generating capacity of 1740 MW (gross summer capacity). Units 3 and 4 (100 MW and 225 MW, respectively) are 1950s-era units thatwere converted from coal to natural gas in 2003. 2 Unit 5 (840 MW) was added in 1972 and uses #6 fuel oil. Unit 6 (575 MW) was built in 2003 and is a combin ed cycle gas combustion turbine with a heat recovery steam generator (HRSG). 3 Six small oil-fired (#2) combustion

1 Prior to a recent court ruling, Ma ryland also claimed jurisdiction to regulate discharges to the Potomac River and NPDES permits were jointly issued. The ruling gave sole authority to the state of Virginia; going forward, Possum Point’s permit will be issued by only Virginia.

2 Units 1 and 2 are retired in place.

3 Unit 6 also has the capability to use #2 fuel oil, but rarely uses it; since startup, Unit 6 has used oil for only approximately 250 hours, including startup and testing activities.2 turbines provide additional peak gene rating capacity at 72 MW (gross summer capacity).

Units 3, 4 and 5 operate as peaking units, w ith a capacity utilization rate (CUR) of 15-20%. Unit 6 is approaching becoming a baseload unit, with a CUR of 75- 80%; in the past, it typically cycled off at night, but has been running continuously in recent months. Facility representatives also noted that Possum Point is an important part of grid reli ability and voltage support in the area.

Natural gas (mostly from the Cove Point liquefied natural gas [LNG] facility in Maryland) is provided via new 14-mile pi peline constructed to supply the new Unit 6. There is no natural gas storage ons ite. Fuel oil arri ves via boat at an

onsite dock and is stored in tanks.

The transmission system is owned by Do minion but is operated by a different

business unit.

4.0 Cooling Water System and Intake Structure

Possum Point has two CWISs on the Potomac River; one for Units 3 and 4 and a second for Unit 6. Units 3 and 4 employ once-through cooling and have a design intake flow (DIF) of 224 million gallons pe r day (mgd) and an actual intake flow (AIF) of 207 mgd. Units 5 and 6 were each constructed with mechanical draft cooling towers. 4 Unit 5 withdraws makeup water from the discharge for Unit 3 and has an AIF of 12-28 mgd. 5 Unit 6 withdraws makeup water from the former CWIS for Units 1 and 2, with an AIF of 6-14 mgd; raw water is sent through a treatment process before being fed to the tower. 6

Each CWIS is a shoreline in take structure with a bar ra ck and standard (i.e., 3/8” coarse mesh) traveling screens, as well as a floating boom to divert debris. A debris trough returns debris and impinged organisms to the river just downstream

4 Unit 5 and 6 cooling towers employ drift eliminators, but do not use plume or noise abatement. Unit 5 has two- eleven (11) cell cooling towers of an older less efficient splash bar tower fill design. The tower fill was replaced in with Marley’s Optibar (more effi cient design of polypropylene material) and partial replacement of broken or missing drif t eliminators. The Unit 5 towers operate at 2 or less cycles of concentration when Unit 5 is generating power and do not currently employ chemical treatment. Biocides for maintaining condenser and equipment cooler cleanliness may need to be added in the future. Unit 6 has one-ten (10) cell cooling tower of a modern design that uses high efficiency honeycomb type fill. The fill is more prone to fouling or plugging so cleaner makeup water is provided and chemical treatment is employed consisting of an acid sulfuric acid for scale control and a biocide sodium hypochlorite (bleach) for organics control. The Unit 6 tower operates at 4 or less cycles of concentration.

5 The circulating pumps for Unit 5 operate continuously, even if the unit is not generating; during these periods, circulating water is not pumped to the top of the towers and is bypassed directly to the basin and

returned to the condenser.

6 The treatment process is clarification for suspended solid removal. The Unit 6 intake also supplies high purity demineralized water for boiler makeup at the facility through further processing by sand filtration, carbon filtration, reverse osmosis, and electrodeionizatio n (EDI). As such, not all of the water withdrawn is for cooling purposes.3 of the screens. The CWIS serving Unit 6 has two 8-foot trave ling screens and one dual flow traveling screen. The CWIS for Units 3 and 4 has two 10-foot screens. Both CWISs have two circulating pumps per unit (one operating and one backup), for a total of 8 pumps. Th e traveling screens are rotated automatically on a timer

or based on a head differential across the screen. The design through-screen velocity at each CWIS is 1.3 feet per second (fps).

Facility representatives noted that they will be replacing the traveling screen on

the former Unit 2 soon. Screen maintenan ce is performed on an as-needed basis, with maintenance typically occurring ever y few years. Inspections by divers are conducted approximately every two years.

Possum Point is capable of recirculating hot water to its CWISs to address icing, but has not needed to do so in several y ears. The CWIS also has an air aspiration

device that can create turbulence at th e CWIS; in recent ye ars, continuously operating the aspirator has been sufficient to control icing.

5.0 Impingement and Entrainment Information

The Potomac River is approximately 1.5 m iles wide at the facility and up to 60 feet deep. The river is tida l, but has fairly small changes in depth. As a result of the brackish waters, a mix of marine a nd freshwater species are present. The facility is also home to many rare bird s that reside in the tidal marshes and surrounding areas.

Possum Point collected impingement samp les in 1976 and again in 2005/2006. In order to facilitate comparison of the data , Possum Point used the same procedure and methodology during both sampling pe riods. During the sampling periods, Possum Point conducted impingement sampling two times a month for a year for a total of 24 sampling events. During each 24-hour sampling event, the facility ran the screens continuously and collected impingement samples from each screen

wash for 10 minutes each hour. The f acility did not conduct entrainment sampling during the 2005/2006 study. 7

The table below shows results from the two impingement studies. The facility collected 18 common species during the tw o sampling periods. In both studies, more fish were collected at night. The total fish counts are raw numbers; they do not reflect an annual estimate of impinged organisms.

Sampling Period

1976 2005/2006 Number of species collected 24 24 + 2 shellfish 1

Primary species White perch

Gizzard shad White perch Bluegill

7 In the 2005/2006 study, the study plan assumed that the facility would not meet the 15% CUR threshold and would therefore not be subject to entrainment requirements.4 Pumpkinseed

Total number of fish collected 4550 703

1 The facility did not sample for shellfish during the 1977 sampling period.

During the 2005/2006 sampling period, Po ssum Point also conducted ambient studies, in which the facility co llected 925 fish from 13 species.

6.0 Cooling Tower Feasibility

The two largest units at Possum Point al ready employ closed-c ycle cooling (see Section 4.0). Facility representatives stated that there are no plans to study retrofitting the remaining units to closed-c ycle cooling. They added that, due to the facility’s location on the peninsula, available space is virtually non-existent. Space may be available further inland, but would require an expansion of the facility’s fenced perimeter.

7.0 Debris Handling

Possum Point does not have significant prob lems with debris loading. Facility representatives did note that there are occasional problem s with hydrilla or logs, but these events do not signifi cantly affect operations.

8.0 Repowering/Future Uses

Possum Point has no current plan s for re-powering or upgrades.

9.0 Cooling Ponds

There are no cooling ponds on site.

10.0 Ownership

Possum Point is owned by Virginia Elect ric and Power Comp any d/b/a Dominion Virginia Power, a subsidiary of Domi nion Resources, Inc., an investor-owned

company.

11.0 316(a)

Possum Point has a BTU heat reject ion limit with no 316 (a) variance.

12.0 Ash Handling

Possum Point no longer burns coal, but sti ll maintains two ash ponds onsite. Pond D (or Delta) was constructed in the 1980s a nd is clay lined. Pond E (Echo) is an unlined pond that was built in the 1960s. Pond E was the primary pond for5 handling wet fly and bottom ash that was sluiced from the facility. 8 Pond E would overflow into another pond (referred to as the beaver pond) and eventually into Quantico Creek. Ash was hydraulically dredged into Pond D for long-term storage, which had a projected lifespan of approximately 25 years when Possum Point converted to natural gas. Discharg es from Pond D, although very rare, were

controlled and flowed into Pond E.

Both ash ponds are regulated by the Virg inia Department of Environmental Quality (DEQ) and are subject to licens ing (five year terms) and annual state inspections. Dominion also c onducts quarterly inspections.

13.0 Air Emissions Controls

Possum Point no longer burns coal and ha s no air emissions control equipment.

14.0 Additional Information

With regard to the 2004 316(b) Phase II rule, Possum Point completed its biological studies including impingement . The facility did not complete technology feasibility evaluations nor did they come to conclusions as to how they would have complied with the 2004 rule . However, facility representatives indicated they would have considered pursuing reduction credits that were achieved by improving generating efficien cy and cooling water intake flows. 9

They thought it was imperative that the new rule offer multiple compliance options to allow each facility to accommoda te site specific issues. Specifically, Dominion Power representatives would like to see rule options that consider waterbody type, as man-made reservoirs likely do not merit entrainment protection.

The former coal pile was located at th e southern end of the peninsula; coal handling equipment remains intact to preserve the facility’s ability to switch fuels again if necessary. Remaining coal left af ter the fuel conversion was stored in the ash ponds. This coal is now being re-pro cessed for use at the Chesterfield Power

Station.

Attachments

Attachment A List of Attendees

Attachment B Aerial Photos

Attachment C Aerial View of Possum Point Power Station Attachment D Possum Point Station Water Flow Diagram

8 Pond E also receives other discharges, such as boiler blowdown and industrial wastewater.

9 Unit 6 is a combined cycle generating unit—it is more efficient that other generating units. Up to 2/3 less cooling water is used since approximately 2/3 of the power generated is from the combustion turbines which provide waste heat to generate steam in the HRSGs and do not require the same cooling water quantity as a steam turbine.6 Attachment A--Lis t of Attendees

Paul Shriner, EPA Jan Matuszko, EPA Josh Hall, EPA Erik Helm, EPA Julie Hewitt, EPA Richard Witt, EPA OGC Shari Goodwin, Tetra Tech Kelly Meadows, Tetra Tech Peter Sherman, Tetra Tech Christine Wong, Tetra Tech John Sunda, SAIC Bill Bolin, Dominion Cathy Taylor, Dominion Bill Clancy, Dominion Jeff Marcell, Dominion

# Copyrighted page/s removed. Copyrighted material is not available in Regulations.gov since it may not be reproduced without consent of the copyright holder.

Please contact the EPA Docket Center, Public Reading Room to view this document.

Address: 1301 Constitution Ave, NW

Room 3334 Washington, DC 20004

Telephone: 202-566-1744

Fax: 202-566-9744

Email: docket-customerservice@epa.gov9 Attachment C—Aerial View of Possum Point Power Station

Please see the attached materials.

Attachment D--Possum Point Station Water Flow Diagram

Please see the attached materials.