Document ID: EPA-HQ-OW-2008-0667-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-11-05T05:00Z

Site Visit Report

	Eddystone Generating Station

1 Industrial Highway

Eddystone, PA 

January 23, 2008

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 understand the cooling water
intake structure (CWIS) technologies in use at facilities, including the
site-specific characteristics of each facility and how these affect the
selection and performance of CWIS technologies.  EPA is also visiting
facilities to better understand cooling water use and specific issues or
technologies that can affect 316(b) compliance.  Eddystone Generating
Station (Eddystone) was selected for a site visit due to its use of
wedgewire screens and its source water body type.

Facility Description

Eddystone is located on a 100-acre site on the Delaware River just south
of the Philadelphia International Airport.  Currently owned by Exelon
and employing approximately 140 people, the facility began operations in
1959.

	

The facility’s permit (PA0013714, expired November 6, 2006) is being
renewed.  Eddystone is required to submit information similar to that
required under the now-suspended Phase II rule (source waterbody data,
impingement mortality and entrainment, design and construction plan) in
July 2008.

	

Electricity Generation and Transmission

Eddystone has 4 generating units.  Units 1 and 2 are nearly identical
supercritical steam boiler-turbine generator coal-fired units and were
built in 1959 and 1960.  These units burn coal from western Pennsylvania
and produce 249 MW and 302 MW, respectively, and have a capacity
utilization rate (CUR) averaging 53% over the last 5 years.  Generally,
one unit is taken offline each year for a 5 week routine maintenance
period.

Units 3 and 4 are peaking units that can use either natural gas or fuel
oil and were built in 1974 and 1976.  These units each produce 380 MW
and historically have a CUR under 15%.

Eddystone also has 4 combustion turbines onsite for additional peaking
and blackout start-up capability.  Each combustion turbine is capable of
producing 15 MW and operate on No. 2 fuel oil. These units do not use
cooling water.

PECO owns the switchyard and distributes the electricity to PJM.

Cooling Water Intake Structure

Units 1 and 2 withdraw water through 16 cylindrical wedgewire tee
screens located on a bulkhead at the shoreline.  These screens were
retrofitted in the early 1990s, when the bulkhead was constructed in
front of the existing intake structure for these units (a traveling
screen configuration similar to that at Units 3 and 4).  To accommodate
the wedgewire screens, the bulkhead is approximately 2-3 times wider
than the original CWIS for Units 1 and 2.  The wedgewire screens are
each approximately 20 feet long and 6 feet in diameter and have a slot
width of 6 mm (1/4 in).  At low water, the screens are approximately 7
feet below the surface, and are 4 feet from the river bottom.  An
automated airburst backwash system sequentially cleans the screens to
follow the movement of the tides and ensure that purged materials are
swept away.  Inspections by divers following dredging operations
indicated that siltation underneath the wedgewire screens does not
appear to be an issue.  Facility representatives stated that the
wedgewire screens have been essentially maintenance free.

Units 3 and 4 employ a total of 8 traditional traveling screens with a
standard 3/8” mesh.  This CWIS also uses several design features to
reduce impingement and entrainment: incorporating lateral escape
passages behind the trash rack, increasing the number of screens to
reduce the intake velocity, and locating the intake entirely flush with
the shoreline (instead of slightly set back).  There is no fish return
for Units 3 and 4, as the permit requires that screened material be
disposed in a landfill.

All four units use once-through cooling.  Units 1 and 2 have a combined
design intake flow (DIF) of 634 million gallons per day (mgd) (317 MGD
each), with a through-screen velocity of 0.4 feet per second (fps). 
Units 3 and 4 have a combined DIF of 834 mgd (417 MGD each), with a
through-screen velocity of approximately 0.6 feet per second (fps). 
Biocides are used once per day in each unit.  Heated effluent is
discharged through a combined return line for all intakes that extends
300 feet into the river.  The delta T between the intake water
temperature and point of discharge ranges from 12-15 degrees.

Impingement and Entrainment Information

Impingement and entrainment studies were conducted in the mid 1970s and
found similar species assemblages to other mid-Atlantic facilities. 
Eddystone representatives stated that the installation of wedgewire
screens at Units 1 and 2 has essentially eliminated impingement.

From April 2005 to April 2006, Eddystone conducted a study to quantify
the entrainment reduction realized by the installation of the wedgewire
screens for Units 1 and 2.  By comparing the entrainment densities to
those seen in samples at Units 3 and 4, the facility noted at least a
40% reduction in entrainment.

In general, the species found were the same as in previous studies,
recognizing that water quality has significantly improved and
populations are higher than in the past.  Additionally, the previous
studies had been conducted in a period of low flow and higher salinity,
suggesting that more estuarine species may be found in the vicinity of
the intake than under normal flow conditions.

Facility representatives stated that additional study results indicate
that the enhanced design features incorporated into the CWIS for Units 3
and 4 have reduced impingement by 30-60% over conventional
configurations.

Prior to selecting wedgewire screens, Eddystone considered a number of
technologies for retrofitting Units 1 and 2, and found that wedgewire
screens were the best choice based on an evaluation of costs and
benefits.  At the time, it was the largest wedgewire screen installation
in the United States and flume studies were conducted to help customize
the design criteria to best meet the facility’s needs.  Facility
representatives estimated the length of downtime for the retrofit to be
about 4-6 months, but noted that issues unrelated to the CWIS retrofit
were also addressed during that time.

In order to comply with the now-suspended Phase II rule, Eddystone would
have demonstrated that Units 1 and 2 meet the impingement and
entrainment reductions over the calculation baseline, and that Units 3
and 4 (not subject to entrainment requirements due to the low CUR) also
exceeded the performance of the calculation baseline.

Cooling Tower Feasibility

Facility representatives stated that cooling towers have not been
extensively considered.  They noted that the existing activities at the
site would make siting difficult: the coal pile, transmission yard, oil
storage tanks, and other structures occupy much of the open space. 
Additionally, the tower design might require plume abatement due to the
proximity to the Philadelphia airport, which would increase the size of
the tower array.

Attachments

Attachment A		List of Attendees

Attachment B		Aerial Photo

Attachment C		Slideshow Presentation

Attachment D		Site Visit Photos

Attachment A--List of Attendees

Paul Shriner, EPA

Jan Matuszko, EPA

Ron Jordan, EPA

Kelly Meadows, Tetra Tech

Shari Goodwin, Tetra Tech

Bob Matty, Exelon

Joseph Kuklinski, Exelon

Walt Masny, Exelon

Diana Hart, Exelon

David Piller, Exelon

David Stewart, Exelon

John Tissue, Exelon

Bob Goshey, Exelon

Ed Veneziale, Exelon

Ron Blye, Normandeau Associates



Attachment B—Aerial Photo

Please see DCN 10-6507B accompanying this document.

Attachment C--Slideshow Presentation

Please see DCN 10-6507A accompanying this document.

Attachment D--Site Visit Photos

Please see DCNs 10-6507C-N accompanying this document.

 Facility representatives added that 40% is the lowest reduction
statistically supported by the data; some results indicated even higher
reductions.

 Facility representatives estimated that the wedgewire screen retrofit
costs were approximately $4.5 million.

 PAGE   

 PAGE   1 

 PAGE   

 PAGE   6