Study Plan for Kentucky Power Plants

Location: Kentucky

Client: E.ON U.S.

Completion Date: Ongoing

Burns & McDonnell is developing a generic study plan for power plants in Kentucky that will need to re-evaluate their discharge limits for temperature and Section 316(a) variances.

Many power plants operate with discharge temperature limits granted under Section 316(a) of the Clean Water Act. Most of the studies to support these variances were conducted 25 or more years ago. Evaluations of these variances were largely not occurring as required with each five-year discharge permit renewal cycle. Substantial evidence, however, exists that hydrological cycles, long-term flows and ambient water temperatures have changed in the past several decades since many of the Section 316(a) variances were issued.

The U.S. Environmental Protection Agency (EPA), therefore, directed certain states to increase attention on thermal discharge limits. The Kentucky Department of Water (KDOW) is now requiring power plants that discharge substantial quantities of warm water to prepare and submit new studies to support their discharge temperature limits with their discharge permit renewal applications.

To streamline the study design and approval process, E.ON U.S. contracted with Burns & McDonnell to develop, in cooperation with the Tennessee Valley Authority, a generic study plan for demonstrating the validity of existing Section 316(a) variances. This plan is to be submitted to the KDOW for approval and subsequently can be used by Kentucky power plants to design the required study.

The plan must have several important qualities:

  • Applicable to the range of conditions represented by all affected power plants in Kentucky
  • Consistent with the EPA's 1977 guidance document for Section 316(a) variance studies
  • Minimizes the scope of work and cost to the utilities

The basic study design describes these basic components:

  1. Thermal discharge plume mapping
  2. Thermal discharge plume modeling
  3. A biological study
  4. A decision tree to evaluate which of these components should be included in the study.

Procedures for each component are specified in as much detail as possible while leaving room for site-specific adaptation. Alternate procedures are given when necessary.

A biological study to demonstrate maintenance of balanced and indigenous aquatic community may be the centerpiece of many Section 316(a) studies. The study plan focuses the biological sampling to the fish community based on:

  • The consideration of fish as integrators of ecological conditions
  • Fish responses to environmental stresses are as indicative of ecological integrity as other communities
  • Fish are relatively easy to collect and process

To further minimize study cost, fish sampling is specified only for summer, when the potential for adverse impacts is greatest, and for autumn, which represents the time when the fish have experienced an annual cycle of overwintering, spawning and potential summer heat stress from the thermal discharge. In addition, the Kentucky Department of Water specified the shellfish community be evaluated by sampling freshwater mussels, and EPA Region IV expects the wildlife community to be studied.