A Flow Modifying Curtain for Reducing Egg Entrainment

HDR was hired by operators of the 286-megawatt (MW) Brooklyn Navy Yard Cogeneration Plant (BNYCP) to address 316(b) compliance for their facility that uses water withdrawn from the East River for once-through cooling.  Because the facility has 2 mm wedgewire screens with low through-slot velocity, it met the New York State’s BTA requirement that impingement mortality be reduced by 84-86%.  However, New York requires that entrainment be reduced by an equivalent percentage. 

Entrainment sampling by NAI found that more than 90 % of the organisms entrained were bay anchovy and cunner eggs and synchronous sampling  of ambient levels of entrainable organisms in front of the intake showed that the majority of these eggs were in the upper layer of the water column. As part of the 316(b) compliance study, HDR examined a suite of alternatives for reducing entrainment at the facility but settled on an innovative approach based on a flow modifying curtain that would enhance the withdrawal from the lower portion of the water column and thereby reduce entrainment of the buoyant eggs that dominated the entrainment estimates. Based on calculations of the curtain’s effectiveness in reducing entrainment NYS accepted it as BTA for entrainment reduction at the facility