                                       

                                  MEMORANDUM



Tetra Tech, Inc.
10306 Eaton Place, Suite 340
Fairfax, VA 22030
phone	703-385-6000
fax	703-385-6007

TO:			Paul Shriner and Jan Matuszko, EPA
FROM:		Kelly Meadows
DATE: 		January 7, 2010 (updated March 10, 2014)

SUBJECT:		Cooling Towers in Brackish Waters

EPA requested that Tetra Tech contact individual facilities regarding the prevalence and design characteristics of cooling towers that used brackish water as a source for makeup flows.  This memo summarizes Tetra Tech's efforts to contact those facilities.

Data Sources

Tetra Tech identified facilities using salt or brackish water as the makeup source from two documents:

   1) Maulbetsch, J. and M. DiFilippo. "Performance, Cost and Environmental Performance of Salt Water Cooling Towers." Prepared for the California Energy Commission. June 2007. Table 4-1.
   2) DiFilippo, M., J. Maulbetsch and K. Zammit. Status, Impacts and Operations of High-Salinity Wet Cooling Towers. PowerPoint presentation. 

Facility Calls

Tetra Tech attempted to contact all manufacturing facilities listed in the above documents that have installed salt water towers since the Clean Water Act was passed in 1972, as well as any electric generating facilities that have installed salt water towers in the past 5 years.

A representative from Dow Chemical in California stated that the facility does not operate a salt water cooling tower.  After further discussion, it appears that the facility may have used a salt water tower at one time (the documentation stated it was built in 1976) but the facility currently uses fresh water and has for quite some time.

A representative from Lansing Smith (a power plant in Lynn Haven, Florida) stated that the facility has been in operation with once-through units since the 1960s, but added a natural gas combined cycle unit in 2001.  The new generating unit uses mechanical draft cooling towers, with the makeup water being withdrawn from the discharge of the once-through units.  The cycle of concentration for the tower is approximately 2.0 and the representative stated that they have had no significant problems with operating the towers and that chemical costs have been approximately as expected.  The facility performs its own maintenance on the towers.  The tower also utilizes a drift eliminator, as the facility has drift limits in its air quality permit.

A representative from Watson (a power plant in Gulfport, Mississippi) stated that their facility has several types of cooling towers.  The facility's Unit 5 was built with a round cooling tower approximately 30 years ago; it was recently demolished and replaced with a new linear bank of towers.  The new towers are mechanical draft with a cycle of concentration between 3 and 7 and were designed with plume and drift abatement.  The tower draws its makeup flows from the discharge canal of the other (once-through) units.  Construction of the new tower took approximately 12 months, with 6 months being required for the basins and another 6 months for the fiberglass structure and other above-ground elements.  The tower was tied into the existing cooling system during a planned 30 day outage, but the facility representative noted that the outage would have been shorter if it had been solely for cooling tower tie-in.  The new tower cost approximately $42 million and appears to be meeting its goals for parasitic power needs, chemical usage, and maintenance.  Watson also has a helper cooling tower in its discharge canal; the tower straddles the canal, draws water up into the tower, cools it, and then allows the water to fall back into the canal.  There are no chemicals in use at the helper towers.

Calls to the following facilities were not returned: Delano Biomass (CA), Intalco Aluminum (WA), St. Johns River Power Park (FL), Crystal River (FL).

Calls to the following facilities were not completed, as contact information could not be located: Pfizer (NC).

Update (March 10, 2014)

EPA received correspondence from Southern Company on June 13, 2011 (see DCN 12-6620) regarding requested corrections to the information in this memo. Southern noted the following:

   * The typical COC for Plant Lansing Smith is 1.5.
   * The COC for Plant Watson's cooling tower ranges from 1-4, depending on source water conductivity. When source water conductivity is high (e.g., due to a lack of rainfall), the COC is near the low end of the range.
   * The cooling tower for Plant Watson's Unit 5 does not utilize plume abatement.


