Sustainability, U.S. clean water act 316(b) final regulations, and best technologies available for design of water intake structures.

Mahmood Naghash

Friday 3 july 2015

10:30 - 10:45h at Africa (level 0)

Themes: (T) Hydro-environment, (ST) Ecohydraulics and ecohydrology, (T) Special session, (ST) Design of intake stations

Parallel session: 15D. Special session: Design of intake stations

The U.S. Environmental Protection Agency (EPA) Section 316(b) guidelines for facilities with cooling water intake structures require that the location, design, construction, and capacity of intake structures reflect the best technology available (BTA) to minimize harmful impacts on the environment. EPA asserts that the withdrawal of cooling water by facilities removes billions of aquatic organisms from waters of the U.S. each year, with most impacts to early life stages of fish and shellfish through impingement and entrainment. The EPA 316(b) regulations for new facilities have been complied with since its inception in 2001 and guidelines for existing facilities was finalized in July 2014 after over a decade long reviews and court appeals. EPA has identified 3 technologies as pre-approved BTA for new facilities which include i) closed-cycle cooling systems, ii) offshore velocity caps, and iii) reduced intake velocities. For existing facilities there are 4 additional technologies to comply with in modifying the existing intake systems. Among the 3 pre-approved BTA the closed-cycle cooling water system is the EPA’s preferred due to its substantial reduction in water withdrawal from natural waters. The other two pre-approved EPA technologies directly affect the design of intake system. The intake inlet velocity criteria (while not directly a technology) results in large inlet structure designs to fulfill the low velocity criterion. The velocity cap technology is required to be offshore at a required distance with least impact to aquatic life. The EPA guidelines are to assure U.S. natural water resources are preserved in a sustainable manner for use by future generation. This paper reviews the sustainability along with EPA 316(b) guidelines on design of water intake structures and evaluates the pre-approved EPA BTA for thermal power plants cooling systems. The additional EPA approved technologies intended for modification of existing facilities also are stated. This paper also addresses innovative measures by the U.S. power industry that have resulted in significant reduction in consumptive water use through recycling of degraded sources of water and use of efficient power technologies minimizing the need for natural waters, protecting the environment and assisting in sustainable use of U.S. natural water resources and protecting aquatic life.

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