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ATTACHMENT 1 SCOPE OF WORK SOUTH RO PLANT CONCENTRATE DISPOSAL PERMIT RENEWAL Project Description and Understanding Indian River County ' s (IRC) South RO water treatment plant (Oslo Road) currently has a permit to dispose of concentrate to a surface water body under Florida Department of Environmental Protection (FDEP) Permit 31 -FL0037940 — Minor NPDES Non-POTW Discharge . The permit allows for 1 . 5 mgd maximum daily flow of concentrate disposal to the South relief canal and expires December 14 , 2005 . A permit renewal application, including supporting data, must be submitted at least 180 days (June 17 , 2005 ) before the expiration date of the permit in accordance with specific condition VII. C . 10 The concentrate, or byproduct of the water treatment process, is currently treated to remove hydrogen sulfide and increase dissolved oxygen. The treated byproduct is discharged through a 14" pipe, approximately 3 , 650 ft long into the Indian River County South Relief Canal, a Class III fresh water body. The outfall is downstream of a control structure and thence 10, 000 feet downstream into the Indian River, which is classified at that point a Class III marine body. Chlorination is performed to primarily eliminate the majority of hydrogen sulfide (H2S ), whereas air is injected into the stream to remove the remaining H2S and increase dissolved oxygen . A mixing zone is approved for three parameters : Gross Alpha, Combined Radium (Ra 226 and Ra228) and specific conductivity, all of which have different and distinct mixing zone limits . Turbidity and chromium were limits originally established under the original permit, however, based on historical levels measured well below standards , limits for these parameter were removed from the previous permit . Through discussions with staff, the South County RO plant has indicated historical failures of toxicity testing for mysidopsis bahia (mysid shrimp) and has reported these results to FDEP . Based on this, it is believed that ion imbalance toxicity exists and a variance for acute toxicity and/or a mixing zone for chronic toxicity will need to be addressed under this permit renewal process . IRC ' s current permit does not require testing for chronic toxicity. It is believed that FDEP will request that IRC conduct ion imbalance review and testing. SCOPE OF SERVICES In general , the following scope of services will include review of existing permit and pertinent data, meetings with FDEP and IRC staff, preparation and submittal of permit application including existing information (majority provided by IRC) , existing mixing models , and no changes in capacity or quality of concentrate, conducting ion imbalance water quality testing to address acute toxicity, toxicity investigation evaluation, and H:\044572009\South RO Plant Concentrate Disposal-revl .doc 1