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WASTE DISCHARGE REQUIREMPTS ORDER NO. • 6 CITY OF LATHROP AND METROPOLITAN LIFE INSURANCE COMPANY CROSSROADS TREATMENT PLANT NO. 1, SAN JOAQUIN COUNTY Well TDS EC Sodium Chloride Sulfate N 3 TKN TCO FC MW-4 3,840 4,780 584 280 1,690 90.4 1.13 DET <1.0 MW-5 648 835 137 53.9 97.1 2.6 <0.5 DET <1.0 TDS denotes total dissolved solids. NO3 denotes nitrate reported as nitrogen. EC denotes electrical conductivity. TKN denotes total Kjeldahl nitrogen. TCO denotes total coliform organisms.FC denotes fecal coliform organisms. DET denotes detected,numerical value not reported. Analyte not detected and detection limit indicated by<0.5 or <1.0. 33. Total coliform organisms were detected in all groundwater samples collected from the five wells located in the proposed land application areas or nearby areas. The laboratory report did not provide an estimated number of organisms per 100 ml sample. The wells have not been disinfected; based on the results of additional groundwater sample events, disinfection of the wells may be required. Disinfection of the wastewater may also be required. 34. Groundwater monitoring data indicates that groundwater quality in the proposed land application areas is impacted by dissolved solids; additionally, nitrate is elevated at Well MW-4. Background groundwater quality may be best represented by the samples collected from Well MW-5, which is upgradient of the proposed land application areas and wastewater treatment facility. The source of the contaminants in the groundwater in the land application areas is uncertain, but may be a result of previous land use. 35. This Order requires that the Discharger continue groundwater monitoring and complete a technical analysis of groundwater monitoring data to determine applicable background concentrations and the nature and extent of groundwater impacts attributable to the discharge, if any. Groundwater Degradation 36. State Water Resources Control Board(SWRCB)Resolution No. 68-16 (hereafter Resolution 68-16 or the "Antidegradation Policy")requires the Board in regulating the discharge of waste to maintain high quality waters of the state until it is demonstrated that any change in quality will be consistent with maximum benefit to the people of the State, will not unreas8nably affect beneficial uses, and will not result in water quality less than that described in the Board's policies (e.g., quality that exceeds water quality objectives). 37. The Board finds that some degradation of groundwater beneath the wastewater treatment plant (excluding the effluent recycling areas) is consistent with Resolution 68-16 provided that: a. The degradation is confined to a specified area; b. The discharger minimizes the degradation by fully implementing, regularly maintaining, and optimally operating best practicable treatment and control (BPTC)measures; c. The degradation is limited to waste constituents typically encountered in municipal wastewater as specified in the groundwater limitations in this Order; and d. The degradation does not result in water quality less than that prescribed in the Basin Plan.