SITE INFORMATION AND CORRESPONDENCE 1980-1999

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Plant, DHS insisted that to ensure that the process used to disinfect the effluent is reliable, wherever there is less than a 20 to 1 dilution, a 2.2 MPN/100 ml, 7-day median is required. The Tentative Permit should be modified to reflect DHS's recommendations of 2.2 MPN/100 ml as a 7-day median. - As a related note,the Tentative Permit states that Dredger Cut is posted as a wastewater disposal area. DeltaKeeper patrols have noted people fishing and swimming in Dredger Cut(both from the bank and boats). Considering that Dredger Cut is contiguous to Bishop Cut and White Slough, there is no practicable way to eliminate water contact and fishing from Dredger Cut. The beneficial use of contact recreation in Dredger Cut should be protected. V. THE MONITORING PLAN IS INSUFFICIENT TO CHARACTERIZE THE WASTESTREAM AND ENSURE COMPLIANCE. A monitoring program must be sufficient to ensure compliance with permit limitations. DeltaKeeper believes that,whenever limitations are expressed in a permit, specific monitoring monitoring requirements, sufficient to detect non-compliance,must also be included. As we discuss below, there are a number of limitations in the Tentative Permit that have no corresponding monitoring requirement. We are also concerned by the inadequacy of required monitoring frequency. A quarterly composite sample represents approximately one percent of a wastestream and is insufficient to adequately characterize the effluent or detect violations. We appreciating the cost of monitoring and the reluctance of dischargers to accept the expense of increased monitoring frequency,. Therefore, we propose that monitoring frequency be driven by monitoring results. When a routine sampling analysis reveals an exceedance of a water quality standard,the Discharger should be required to conduct additional sampling. This additional sampling would help define the magnitude and extent of the problem. This requirement would place no additional burden on treatment plants that are properly operated and not experiencing exceedances of permit limitations. A. Influent Monitoring Of Wastewater. There is no requirement to monitor influent for pH. A continuous reading meter should be required. PH is related to solubility of metals. In general,pH values less than 6 or greater than 9 have been known to hinder biological treatment processes. As a result, soluble heavy metals may create toxicity that interferes with biological processes (such as sludge digestion) that intensifies with acidic or base pH conditions. Furthermore, metal removal in POTWs is often impaired,particularly in the primary treatment,by acidic or basic conditions. The Regional Board has found that a reasonable potential exists for excursions of zinc, cyanide and lead. DeltaKeeper, in reviewing EPA's Guidance Manual For Preventing Interference At POTWs,has noted that a DeltaKeeper,Tentative NPDES Permit,Lodi, 17 December 1999,Page 8.