The client was seeking an alternative thermal effluent limitation for its Will County power plant in lieu of the more stringent thermal water quality standards that were recently applied to its receiving stream. As a nationally recognized expert in the development of successful §316(a) Demonstrations, EA was called upon from the outset to design and implement the study plan in conformance with state and federal regulatory requirements, including biological, physical, and chemical evaluations of the source waterbody to determine whether higher thermal compliance temperatures would have any significant adverse impact on the balanced, indigenous aquatic community. EA was also made responsible for all the primary field, technical and regulatory support needed for the development and ultimate proposal of alternative thermal effluent standards.
Based on the site-specific historical database, a list of Representative Important Species was established by EA and approved by the state regulatory agencies. Because of the station’s long operational history, this Demonstration included both Retrospective and Prospective assessments. The Retrospective portion involved an extensive literature review and analysis of all available historical biological and water quality data available for the source water to demonstrate no appreciable harm from past operation of the station. Biotic categories evaluated included phytoplankton, habitat formers, zooplankton, shellfish and macroinvertebrates, fish, and other vertebrate wildlife.
EA also carried out 2 years of new field data collection necessary to provide information to satisfy all the U.S. Environmental Protection Agency §316(a) draft guidance document requirements, including fisheries surveys, habitat evaluation, and the performance of seasonal thermal plume studies. The thermal monitoring work provided the information necessary for the development and implementation of a site-specific, three-dimensional thermal hydrodynamic model used to characterize the expected extent of the station thermal plume under various operating scenarios and developed appropriate outputs for use in the detailed biological thermal effects analyses.
On the client’s behalf, EA interfaced with Illinois regulatory and natural resources agencies on thermal and state threatened and endangered species concerns and provided scientific support to limit the need for extensive additional monitoring while still maintaining a strong case for acceptance of alternative thermal effluent limitations. The comprehensive §316(a) Demonstration document prepared by EA was approved by the Illinois Pollution Control Board.
