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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
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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cooling towers, with the makeup water being withdrawn from the discharge of the oncethrough units. The cycle of concentration1

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 72and were designed with plume and drift abatement.3 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 aboveground 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 million4and 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).

 

1 Cycle of concentration (COC) represents the accumulation of dissolved minerals in the recirculated 

cooling water. Discharge of a portion of the water (called “blowdown”) is used to control the buildup of 

these minerals. Cycles of concentration can be measured as the ratio of chloride levels in the recirculated 

water or blowdown relative to the chloride levels in the source water, or makeup water.

2 Due to the tidal activity near the facility, as well as precipitation, salinity can vary widely; the frequency 

of blowdown depends on the buildup within the circulating water and varies accordingly.

3 The facility representative noted that there is a nearby highway.

4 The facility representative noted that this cost does not include any retrofit costs, as much of this 

infrastructure was already in place from the previous set of cooling towers.
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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.