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 Environmental 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 

manufacturing facilities. As part of this process, EPA staff is visiting electric generators 

and manufacturers to better understand the cooling water intake structure (CWIS) 

technologies in use at facilities, including the site-specific characteristics of each facility

and how these affect the selection and performance of CWIS 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-cycle cooling.

1

 Unfortunately, due to 

scheduling conflicts, EPA is unable to visit the facility. However, Tetra Tech staff was

able to speak to facility superintendant Jeffrey Pietka on July 29, 2009 and March 5, 2010

to gather more information about the facility. A summary of the discussion is presented 

below.

 

1 Winnetka is one of only 25 Phase III power 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

Facility Information

Winnetka Power Plant is located in the Village of Winnetka, a northern suburb 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 municipality and has three natural gas-fired steam electric generating units and 

two diesel combustion units with a total capacity 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 small site on the waterfront and sits between public and 

private beaches, parks, and a boat ramp, and is in close proximity to hundreds of highvalue homes.3

The facility uses a shoreline intake structure with an intake canal and coarse-mesh 

vertical traveling screens. The DIF 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 any impingement or entrainment studies.

Despite the low intake flows (and subsequently smaller cooling tower footprint), 

installing a close-cycle cooling system 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 closed-cycle system 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 more 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.