Document ID: EPA-HQ-OW-2008-0667-0008
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-11-05T05:00Z

Site Visit Report

	Logan Generating Plant

76 Route 130 South

Swedesboro, NJ

January 22, 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.  Logan Generating Plant
(Logan) was selected for a site visit due to its use of a fine mesh
cylindrical wedgewire screen and its proximity to the Washington, D.C.
area and other site visit locations.

Facility Description

Logan, located on a 105 acre site along the Delaware River, began
operations in 1994.  The facility is owned by Cogentrix and employs
approximately 55 staff.

Logan operates under a zero discharge NPDES permit (NJ0076872, expires
September 30, 2011) but withdraws water to make up for evaporative
losses in the cooling tower and for steam that is sold to nearby
industrial sites.  Additionally, the facility is permitted to reject
chlorides from its reverse osmosis unit approximately once every 2
years.  The facility has a stormwater permit that addresses the four
basins onsite (2 percolation basins, 1 treatment basin, and 1 coal pile
runoff basin) that discharge to one of two outfalls:  one to the
Delaware river and one to a tributary of the Delaware River.

Logan also operates under a permit from the Delaware River Basin
Commission (DRBC), which regulates dischargers in the watershed.  The
facility is charged a fee by DRBC for its water withdrawals to make up
for evaporative losses from the bank of cooling towers. In addition, the
facility operates under a permit with the state of New Jersey as it
withdraws water from the Jersey shore.

Electricity Generation and Transmission

Logan is a coal-fired cogeneration plant with one generating unit that
produces 245 MW (gross) and 230 MW (net) for local household use.  Logan
also provides steam to a neighboring chemical plant. The facility uses
bituminous coal from West Virginia, which is transported by rail to
Baltimore and then by barge to the facility.  Start-up operations, which
typically last six to ten hours, use no. 2 fuel oil.  The facility
typically operates continuously, but is not a baseload generator.  The
capacity utilization over the past few years has been approximately 80%,
but may drop to as low as 25%.  The facility maintains a minimum of 50
MW (at 25% capacity utilization) at all times.  

Atlantic Electric owns the transmission yard and sells the power to
Conectiv.  Most of the electricity generated is used in the nearby metro
area.

Cooling Water Intake Structure

Logan’s CWIS is located at the end of a 1000 foot pier extending into
the Delaware River.  The pier also serves as the receiving point for the
facility’s coal shipments.  Two fine mesh 316 stainless steel (1
mm/.039 in slot width) cylindrical wedgewire screens (each approximately
11 feet long and 3.5 feet in diameter) withdraw water at a depth of
approximately 13 feet below the surface to a common intake well, which
then supplies the facility.  The design through-screen velocity of the
screens is 0.25 feet per second (fps).  The stainless steel screens are
cleaned 1-2 times per day by a forced air blowback system triggered by a
head differential between the river and the intake well.  The screens
are inspected by divers at least once per year and the intake area is
dredged every 3-4 years to accommodate barge traffic.

Behind each screen are three circulating pumps (two operate with one as
a backup) rated at 1050 gallons per minute (gpm) each, for a total
design intake flow of 6.05 million gallons per day (mgd).

The fine mesh wedgewire screens were selected as a result of litigation
during the permitting and construction phase for the facility.  A
Delaware court decision (based on concerns over striped bass
populations) specified intake design parameters and it was determined
that the screens were appropriate to meet these parameters.

The facility has a recirculating cooling water system with a 50 foot
tall, 6-cell mechanical draft cooling tower constructed of pressure
treated red wood.  Two circulating pumps (each 55,000 gpm) pump water
from the condensers to the towers and back.  The condenser was designed
for a delta T of 20 degrees.  Two-speed fans are used for cooling in the
tower.  Facility representatives could not recall any complaints
regarding the plume or noise from the towers.

The facility has never had any difficulty in withdrawing sufficient
flows to meet its cooling needs, but droughts do affect discharges and
other internal operational activities such as the load to the system.

When the facility was constructed, a 30 year lifespan was used for most
design elements, such as fuel contracts.  It was assumed that the
wedgewire screens would also have a similar lifespan.

Logan has a scheduled outage of approximately 2-3 weeks per year.

Facility representatives stated that the wedgewire screens have been
virtually maintenance free, noting that other facility operators have
reviewed the design.  The representatives also stated that they would
use the same design again if the plant were built today.  The only
concern is over the potential for sedimentat accumulation below the
intake, but past experience has shown that this is not a significant
issue.  The screens (and intake pipes leading to the facility) do
experience some icing in winter, but these conditions would affect any
intake technology and have not impacted the facility’s ability to
operate.  In the few instances where an extended freezing period has
occurred, the facility operates the air sparging more frequently or
continuously.

Impingement and Entrainment Information

An initial study was conducted in 1992 to demonstrate the effectiveness
of the technology in reducing losses of striped bass larvae.  Logan has
not conducted any follow-up biological studies since the original study
in 1992, as it is unlikely to be required to further reduce its
impingement and entrainment.

Cooling Tower Feasibility

As described above, Logan already uses a closed-cycle cooling system.

Additional Information

Logan was constructed in an area where dredged materials from the
Delaware River were used to fill wetlands.  As a result, the
facility’s initial NPDES permit required them to mitigate wetland
losses.  Logan has worked with the US Fish and Wildlife Service and
other agencies in restoring the wetlands onsite.  It continues to
voluntarily plant wetland related species in an effort to re-generate
wetlands.

Logan produces a dry fly ash and wet bottom ash.  All ash is hauled
off-site for beneficial re-uses such as capping of landfills and use in
the Wilmington wastewater treatment plant.

Attachments

Attachment A		List of Attendees

Attachment B		Aerial Photo

Attachment C		Flow Balance Diagram

Attachment D		Diagram of Wedgewire Screen Assembly

Attachment E	“Evaluation of the effectiveness of intake wedgewire
screens.”  Chris Ehrler and Carol Raifsnider.  Environmental Science
and policy.  Vol 3, supplement 1, Sept 2000, pages 361-368.

Attachment F		Site Visit Photos



Attachment A--List of Attendees

Paul Shriner, EPA

Jan Matuszko, EPA

Ron Jordan, EPA

Shari Goodwin, Tetra Tech

Kelly Meadows, Tetra Tech

Terry Shannon, Cogentrix

John Kersch, Cogentrix

Mike Salvador, Cogentrix

Attachment B—Aerial Photo

Please see DCN 10-6509D accompanying this document.

Attachment C--Flow Balance Diagram

Please see DCN 10-6509A accompanying this document.

Attachment D--Diagram of Wedgewire Screen Assembly

Please see DCN 10-6509B accompanying this document.

Attachment E--“Evaluation of the effectiveness of intake wedgewire
screens.”  Chris Ehrler and Carol Raifsnider.  Environmental Science
and policy.  Vol 3, supplement 1, Sept 2000, pages 361-368.

Please see DCN 10-6509C accompanying this document.  Document already
appears in the record at DCN 5-4335 in the Phase II NODA docket.

Attachment F--Site Visit Photos

Please see DCNs 10-6509E-HH accompanying this document.

 Logan generates approximately 1.6 million pounds of steam per hour for
its turbine.  Approximately 50,000 pounds of steam is extracted for sale
to other users, e.g., a neighboring chemical processing facility, after
it has passed through the turbines.  This leads to a loss of operational
efficiency, as Logan does not recover the condensate to re-use in its
boiler.

 The coal pile run-off basin has a 60 mL double liner.  The underdrain
ties into the stormwater permit.  The facility noted the discharge can
cause low pH issues.

 Facility representatives noted that New Jersey no longer issues new
permits for coal-fired facilities.

 The cooling towers were installed during construction of the plant.  

 PAGE   

 PAGE   6