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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 request ed 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 . Th is memo summarizes Tetra Tech’s efforts to conta ct 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 an y electric generating facilities that have installed salt water towers in the past 5 ye ars. A representative from Dow Chemical in California stated that the facility d oes not operate a salt water cooling tower. After further discussion, it appears that the facility2

may have used a salt water tower at one time (the documentation stated it was built in 1976) but the facilit y currently uses fresh water and has for quite some time. A representative from Lansing Sm ith (a power plant in Ly nn Haven, Florida) stated that the facility has been in operation with once

- through units since the 1960s, but added a natural gas combined cy cle 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 The new generating unit uses mechanical draft cooling towers, with the makeup water being withdrawn from the discharge of the once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 cy cle of concentration 1 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. T he 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 Gu lfport, Mississippi) stated that their facility has several t ypes of cooling towers. The facility ’s Unit 5 was built with a round cooling tower approximately 30 y ears ago ; it was recentl y demolished and replace d with a new linear bank of towers . The new towers are mechanical draft with a cy cle of concentration between 3 and 7 2 and 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 above

ground elements. The tower was tied into the existing cooling sy stem during a planned 30 day outage, but the facility

re presentative noted that the outage would have been shorter if it had been solely for cooling tower tie

- in. The new tower cost approximately $42 million4 and appears to be meeting its goals for parasitic power needs, chemical usage, and maintenance. Watso n 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 foll owing facilities were not returned: Delano Biomass (CA), Intalco Aluminum (WA) , St. Johns River Power Park (FL) , Cry stal River (FL)

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

.

1 Cy cle of concentration (COC) represents the accumulation of dissolved minerals in the recirculated cooling water. Discharge of a portion of the water (called “blow down”) is used to control the buildup of these minerals. Cycles of concentration can be meas ured as the ratio of chloride levels in the recirculated water or blow down relative to the chloride levels in the source w ater, or makeup water. 2 Due to the tidal activity near the facility, as well as precipit ation, salinity can vary widely; the frequenc y 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.3

**Update (M arch 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 ty

pical COC for Plant L ansing 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.