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Home My WebLink About06.a.4) (Handout)4P • 0 .0• A4 ) (Nandou*) Whole Effluent Toxicity April 7, 2011 Margaret P. Orr, P.E. Bhupinder Dahliwal Central Contra Costa Sanitary District Overview •Issue • Original Program • Central San early findings • Proposed Policy • Implications • Next Steps Central Contra Costa Sanitary District 1 �. ` V Issue • SWRCB has proposed to replace the current Whole Effluent Toxicity Test (WET) statistical analysis methods with new Test of Significant Toxicity (TST) method Current CCCSD Toxicity Testing • Developed in 1986 • Scientifically based • Revisions 1991 • Five dilutions • Calculation does not incorporate standard deviation • Monitoring in Region 2 • Two decades 2 i Early Findings 1990's • CCCSD detected measured toxicity • Toxicity Identification Evaluation • Organophosphate pesticides • Toxicity Reduction Evaluation • Extensive Public outreach • Chlorpyrifos no longer used by individuals • Cost hundreds of thousands • Led to ban of pesticides Proposed Policy Changes • How testing is conducted • Currently series of dilutions • Proposed one dilution • Statistical Test Method • Currently use t -test • Innocent until proven guilty • Proposed TST Method • Guilty until proven innocent 3 Implications • Will create false violations • Effluent deemed toxic 5 -58% of the time • Based on statistical method it No effect observed in the receiving water • Impairment listing of receiving water • TMDL development • Effluent violations • Enforcement action • Potential for citizen lawsuits • Undermine public perception • Recycled water CCCSD Red Abalone Toxicity Data Analysis Using Current and the Proposed TST Methodology (IWC =10 %) n Current Methodology TST Methodology Test Dace Toxicity Units TU Trigger Yes1NO Teal Pess/Fell Trigger Yee1NO Cosy Trigger Permit Vloletlon 2107 7.0 NO PASS NO 41W 70 NO PASS NO 6107 12 NO FAIL YES 515000 8107 7,3 NO PASS NO 10107 76 NO PASS NO 12 8.3 NO PASS NO 2108 10.5 NO FAIL YES 515000 4105 75 NO PASS NO 6108 92 NO FAIL YES $15000 9108 105 NO FAIL YES $15000 YES 11 77 NO PASS NO 1109 114 YES FAIL YES 515000 4109 77 NO PASS NO 5109 107 YES FAIL YES 515000 7109 195 YES FAIL YES $15000 YES 8109 78 TIE I PASS NO 9109 126 515000 TIE I FAIL YES 515000 12_09 158 I FAIL YES $15000 YES 2110 3.3 NO PASS NO 4 38 NO I PASS NO 6110 <2 NO PASS NO n l f Next Steps • Meetings with SWRCB • April 18, 2011 • NACWA