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REGIONAL BOARD RESPONSE (STMCB/OCC FILE A-1483) 11-
<br /> PETITION FOR REVIEW OF WASTE DISCHARGE REQUIREMENTS
<br /> ORDER NOS. R5-2002-0083 AND R5-2002-0084
<br /> CITY OF STOCKTON REGIONAL WASTEWATER CONTROL FACILITY
<br /> limitation is less than 2.5 times the CCC in all cases, the 4-day average cannot exceed the maximum
<br /> daily limitation.
<br /> During preparation of the NPDES permit adopted in 1994, the Discharger submitted information
<br /> showing it was not cost effective to consistently achieve monthly average ammonia-N effluent limits of
<br /> 0.5 mg/L. However,treatment designed to achieve a monthly average of 2 mg/L will likely provide an
<br /> effluent of 0.5 mg/L much of the time, and will be more cost effective to construct and operate.
<br /> Therefore, the adopted permit requires the same ammonia-N effluent limits as the 1994 permit, 5 mg/L
<br /> (daily maximum) and 2 mg/L(monthly average). These values are within the range of calculated limits
<br /> and will provide a significant improvement to water quality.
<br /> THIRD BASIS: PERMIT REQUIREMENTS PERTAINING TO DISINFECTION/
<br /> FILTRATION
<br /> Stockton requests that the State Board direct the Regional Board to modify the disinfection and
<br /> filtration requirements, tertiary treatment operational requirements, and modify the findings,
<br /> conclusions, and effluent limitations for coliform and turbidity.
<br /> The Basin Plan designates the beneficial uses of domestic supply, agricultural supply, and body contact
<br /> and non-body contact water recreation for the SJR. The Regional Board determined that at times there is
<br /> little or no dilution in the SJR in the vicinity of the discharge. Recreational uses identified in the
<br /> immediate vicinity of the RWCF outfall include boating,water skiing,jet skiing, swimming, and fishing
<br /> (both fish and invertebrates). A number of agricultural intakes have been identified through a search of
<br /> the State Board, Water Rights Division database. Within an approximate two-mile radius of the outfall
<br /> there are approximately ten diverters, including the Stockton Golf and Country Club, which draws as
<br /> much as 1.15 cubic feet per second of SJR water near Smith Canal for irrigation of its golf course and
<br /> landscaping. Additionally, subsistence and sports fishing/shellfish harvesting is prevalent in the
<br /> immediate vicinity of the RWCF outfall.
<br /> To protect these beneficial uses, the Regional Board found that the wastewater must be disinfected and
<br /> adequately treated to prevent disease. The principal infectious agents (pathogens) that may be present in
<br /> raw sewage may be classified into three broad groups; bacteria,parasites and viruses. These pathogens
<br /> include Entamoeba histolytica, Giardia lambia, Balantidium coli,Ascaris lumbricoides, Ancylostoma
<br /> duodenale, Necator americanus, Ancylostoma, Strongyloides stercoralis, Trichuris trichiura, Taenia,
<br /> Entrobius vermicularis, Echinococcus granulosus, Shigella, Salmonella typhi, Salmonella, Vibrio
<br /> cholerae, Escherichia coli, Yersinia enterocolitica, Leptospira, enteroviruses (71 types), poliovirus,
<br /> echovirus, coxsackie virus,hepatitis A virus, adenovirus (31 types),rotavirus, and parvovirus (2 types).
<br /> In addition, Giardia and Cryptosporidium have become more of a concern to health officials, drinking
<br /> water purveyors, and the public in recent years.
<br /> The 1994 Permit recognized the possibility of a health risk from pathogens in the Stockton discharge.
<br /> Because the available models indicated only 4:1 long-term dilution was available in the River, the
<br /> Regional Board decided that Stockton should conduct a Health Risk Assessment (HRA) study to
<br /> determine the pathogen impacts of the discharge prior to the Regional Board determining whether Title
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