Document ID: EPA-HQ-OW-2008-0667-0591
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-04-20T04:00Z

MEMORANDUM

Tetra Tech, Inc.

10306 Eaton Place, Suite 340

Fairfax, VA 22030

phone	703-385-6000

fax	703-385-6007

TO:			Record

FROM:		Kelly Meadows, Tetra Tech

DATE: 		March 19, 2008

SUBJECT:		Brooklyn Navy Yard teleconference notes

The Environmental Protection Agency (EPA) is in the process of revising
its 2004 316(b) Phase II regulation.  As part of this process, EPA staff
is visiting several electric generators to better understand the cooling
water intake structure (CWIS) technologies in use at typical facilities,
including the site-specific characteristics of each facility and how
these affect the selection and performance of CWIS technologies.  

The Brooklyn Navy Yard Cogeneration (Brooklyn) facility was identified
as a site of interest due to its use of fine mesh wedgewire screens. 
Unfortunately, due to scheduling conflicts, EPA is unable to visit the
facility.  However, Tetra Tech staff was able to speak to facility
representatives about the performance of their CWIS technology on March
11, 2008.  A summary of the discussion is presented below.

Facility Information

Brooklyn is located in New York City in the historic Brooklyn Navy Yard
and began operations in 1996.  It withdraws from the East River.

CWIS Information

Brooklyn employs 4 fine mesh wedgewire screens that have a mesh slot
size of 2 mm.  Each screen is 6 feet in diameter and 15 feet long and
was thought to be the largest fine mesh screens in the United States at
the time of construction.  The design intake flow (DIF) for each screen
is 17,300 gpm (24.9 million gallons per day [MGD]) for a total DIF of
99.6 MGD.  Through flow limitations in its NPDES permit conditions, the
facility is only permitted to withdraw 72 MGD in the summer and 55 MGD
in other seasons.

Operational Information

Facility representatives stated that the screens require significant
maintenance and that, given the opportunity, the facility would use a
different intake technology in designing the CWIS.  The East River has a
significant tidal surge, which, when combined with vessel traffic, leads
to a large volume of trash bypassing the trash rack and clogging the
screens.  Additionally, the water quality in the river has improved
substantially in the last 10-15 years (a facility upriver adds a
significant amount of dissolved oxygen), which has led to an increase in
biofouling organisms.  The facility performs a monthly cleaning by
divers to remove seagrasses and other organisms.  The facility also uses
biocides four times per year.  Facility representatives estimated that
at least $50,000 is spent each year in maintenance for the screens.

Biological Information

The facility conducted an entrainment monitoring study in 1997 following
plant startup.  Its NPDES permit is currently being renewed and the
facility expects that another entrainment study will be required. 
Facility representatives noted that the resurgence of the wildlife in
the river makes the interpretation of any monitoring results difficult,
as the number of organisms in the ambient waters increases annually.

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