ENB Region 3 Completed Applications 06/25/2003

Modification and renewal of the Danskammer Generating Station (Danskammer)SPDES permit to require that the permittee, Dynegy Northeast Generation, Inc. (Dynegy), reduce entrainment and impingement impacts to aquatic organisms of the Hudson River from the operation of the Danskammer once through cooling water withdrawal. Reductions are to be accomplished through:  

adjustment of the cooling water flow regime on a daily basis as the existing pump configuration allows and Hudson River water temperature dictates;

changing the May to October temperature differential (delta T) restriction for more flexible flow volume adjustment;

scheduling of routine periodic maintenance (3 to 8 weeks duration) for each of the generating units to occur during early spring entrainable organism abundance period; and,

seasonal installation of a sonic deterrent system.

These measures are required to provide immediate reductions of 70% for entrainment and 85% for impingement impacts from issuance of the permit.  In addition, Dynegy is required to prepare a feasibility study that will result in the deployment of a Marine Life Exclusion System™ (MLES™) or alternate technology that will achieve impact reductions approaching that which could be achieved by closed cycle cooling in year five of the permit.  If the study concludes that either a MLES™ or alternate technology is not feasible, the permit requires Dynegy to reduce impacts from entrainment by 80% and from impingement by 90% for the duration of the permit term.

Technology and water quality assessments of the existing permit limits were conducted and, as a result, existing limits changed for total: Copper; Mercury; Residual Chlorine; Selenium; and, Vanadium.  The draft SPDES permit requires that a tri-axial thermal study be conducted to assess mixing zone requirements. A legislative hearing on the application will be held on July 31, 2003. For additional information, please see the Hearing Notice.