The 5-million-gal-per-day (mgd) Taunton River Desalination Plant had to meet local, state and federal regulatory requirements, including 316b requirements for fish egg and larvae exclusion. There was significant concern regarding the potential impact to the migrating spawning fish that pass by the project site seasonally. The system was designed to require minimal operator interface with continuous automated backwash cycle.
Challenges faced include a surface water intake located on an anadromous river, and being subject to extensive environmental regulations for the prevention of entrainment or impingement of all life stages of fish egg and larvae that occur at the intake location. Before receiving approval from the various agencies to install and operate the system, extensive testing using full-size filter elements and live fish eggs and larvae was performed and reported on by Alden Labs. The Alden testing confirmed that the filter eliminates 100% entrainment of the occurring eggs and larvae and that the effects of impingement are minimized to an acceptable level.
Also, because the river is heavily laden with other organic and inorganic matter, backwashing of the 40-micron filter is difficult and has been achieved by means of an automated air/water burst system that provides segmented washing of the filter elements in accordance with a programmable timer which is set in accordance with the varying seasonal load. Recent performance tests have proven the system’s cleaning capability with less than 1% consumption of filtered water for backwashing.