1 

### MEMORANDUM

Tetra Tech, Inc. 10306 Eaton Place, Suite 340 Fairfax, VA 22030 phone 703 - 385 - 6000 fax 703 - 385 - 6007
DATE: March 5, 2010 TO : 316(b) Record FROM : Kelly

Meadows, Tetra Tech SUBJECT: Winnetka Power Plant teleconference notes The Env ironmental 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 manufacturi ng facilities. As part of this process, EPA staff is visiting electric generators and manufacturers to better understand the cooling water intake structure (CWI S) technologies in use at facilities, including the site

- specific characteristics of each facil ity and how these affect the selection and performance of CWI S technologies. EPA is also visiting facilities to better understand cooling water use and specific issues or technologies that can affect 316(b) compliance. The Winnetka Power Plant ( Winnetka ) was identified as a site of interest due to its low design intake flow (DIF) without using closed

- cy cle cooling
. 1 Unfortunately , due to scheduling conflicts, EPA is unable to visit the facility . However, Tetra Tech staff was able to speak to facility su perintendant Jeffrey

Pietka on July

29, 2009 and March 5, 2010 to gather more information about the facilit y . A summary of the discussion is presented below.

1 Winnetka is one of only 25 Phase III pow er plants with a DIF below 50 million gallons per day (mgd) that does not employ closed

- cycle cooling. In this case, the low flow is simply due to the small size of the generating unit.2

Facilit y Information Winnetka Power Plant is located in the Village of Winnetka, a northern su burb of Chicago with a population of about 15,000 . It withdraws once - through cooling water from Lake Michigan and began operations in 1900. The facility is owned and operated by the municipalit y and has three natural gas - fired steam electric generating unit s and two diesel combustion units with a total capacit y of 32 MW. 2 The capacity utilization rate for the facility

is approximately 5 %. The facility currently has no plans for repowering or adding new generating units. The facility

is located on a sma ll site on the waterfront and sits between public and private beaches, parks, and a boat ramp, and is in close proximity to hundreds of high

value homes. 3 The facility

uses a shoreline intake structure with an intake canal and coarse

- mesh vertical traveli ng screens . The DI F for the facility is 15.7 million gallons per day and when operating, the actual intake flow is 5.2 mgd. The facility

has not conducted an y impingement or entrainment studies. Despite the low intake flows (and subsequentl y s maller coo ling tower footprint) , installing a close

- cy cle cooling s ys tem would likely be difficult at Winnetka due to space constraints ; the small site does not offer significant space and the close proximity of residences would make siting and permitting a close d

- c ycl e sy stem very difficult.

2 All five units utilize lake water for cooling. The combustion units were installed in 1979 and no major renovations (e.g., boiler replacement, etc.) have been completed since that time. 3 Using aerial photos, it is estimated that the site is no mor e than 5 acres, with existing structures, forest, and beach occupying most of the area. There are also a half dozen homes within 200 feet of the facility.