Challenge
Clean Water Act under Section 316(b) and evaluate the feasibility, cost and impacts of at least three technologies to reduce fish larval and egg entrainment: retrofitting once-through cooling systems to closed-cycle cooling systems; replacing coarse-mesh on intake screens with fine-mesh; and using alternate water sources (40 CFR 122.21(r)(10)). The regulations also require each facility to evaluate impacts such as: changes in energy use, emissions, noise, safety, reliability, and consumptive use of water.
Approach
ASA prepared site-specific feasibility evaluations for facilities in Illinois, Florida, New Hampshire, Delaware, North Dakota, and Indiana, coordinating with biologists and economists.
ASA sized key equipment and assessed construction methods, routes, and durations, considering the retrofit compatibility with existing infrastructure (e.g. condensers or circulating water pumps) with new components (e.g. closed-cycle cooling towers or fine-mesh screens). The fine-mesh evaluation considers replacing the coarse-mesh on existing screens with fine-mesh; expanding the intake structure to maintain reasonably low intake velocities; and seasonal overlays of fine-mesh over coarse-mesh. ASA prepared cost estimates using vendor quotations, data from past projects, client information, and other costing tools with an accuracy goal of +50/-30 percent.
Changes in energy use were estimated using equipment operations and hydraulics.
Solution
Feasibility and cost evaluation reports (122.21(r)(10)) and non-water quality, environmental and other impacts reports (122.21(r)(12)) prepared by ASA have been peer reviewed by third party engineering experts and determined to be sufficient in their rigor and detail. Acceptance of ASA feasibility evaluation reports by peer reviewers has created a more streamlined and cost-effective compliance process for our power facility clients.
