An Evaluation of Exclusionary Devices at the Taunton River Desalination Plant

The Taunton River Desalination Plant (TRDP) is located on the shore of the Taunton River in the Town of Dighton, Massachusetts.  The TRDP currently provides water to the City of Brockton and is capable of providing five million gallons of potable water per day to the City of Brockton and surrounding communities in southeastern Massachusetts. The plant withdraws brackish water from the Taunton River and discharges blended brine from desalination activities into the river through the plant’s intake structure.

At the request of regulatory agencies, including the Water Resource Commission, an extensive fisheries, impingement, entrainment, and water quality monitoring program was undertaken.  The monitoring program was designed to quantify on-site impingement and entrainment by comparison with in-river ichthyoplankton and finfish sampling during operation of the TRDP.  The goal of the operational monitoring was to summarize impingement and entrainment impacts and verify that the design and operation of the TRDP minimizes impacts to all life stages of fisheries resources and water quality parameters.

The focus of this presentation is an evaluation of the exclusionary devices used to minimize impingement and entrainment of aquatic organisms at TRDP.  TRDP incorporated a series of redundant mechanisms in the design to reduce losses. The first line of defense in the exclusionary netting system (Gunderboom Marine Life Exclusion System TM), outfitted with an airburst system.  The second and third lines of protection are the trash racks, located at the mouth of the intake structure, and the permanent wedgewire screens positioned behind the trash racks. The Johnson screens, located behind the wedgewire screens, provide the last line of protection.  The results of the two year monitoring program indicate that the exclusionary devices are effective at preventing or minimizing impingement and entrainment of fish eggs, larvae, juveniles and adults at TRDP.