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WASTE DISCHARGE REQUIREMENTS -2- COUNTY OF SAN JOAQUIN COUNTY SERVICE AREA NO. 15 WWTP SAN JOAQUIN COUNTY 6. The County Service Area No. 15 Wastewater Treatment Plant proposes to discharge 0.08 mgd of monthly average flow from commercial and light industry wastewater to land. The monthly average flow of 0.08 mgd includes existing flow plus a 33% flow increase through annexation. The facility utilizes a package treatment plant which consists of an activated sludge process with an aerated contact tank followed by a concentric ring clarifier. Chlorination is employed prior to discharging into the percolation/evaporation ponds. A fourth pond is used as a sludge drying bed. The flow is rotated among the ponds to allow for mosquito control and discing of the ponds to control the weed growth. Ground water in this area occurs at 90 feet below the ground surface with a south-westerly flow. 7. On 30 October 1991, West Yost and Associates, an engineering consultant retained by the County, submitted an evaluation and expansion study on the County Service Area No. 15 WWTP. The study notes that with a peaking factor of 3.25, the maximum short duration that should be allowed based on clarifier capacity was estimated to be at 0.405 mgd and average rated capacity of 0.125 mgd on the existing wastewater treatment facility. The original rated capacity design of 0.20 mgd was assumed to be calculated on a minimal peaking factor by the manufacturer, in 1966. Additionally, the Discharger lacks the ability to shut the facility for routine maintenance. The County's long-term intent for this facility is to annex the outlet to the City of Stockton's Regional Wastewater Treatment Facility. 8. The County Service Area No. 15 generates approximately 600 ft' of dry sludge annually. The sludge in the designated drying pond is incorporated into the soil by discing annually. 9. The facility is located in a flood zone according to the Federal Emergency Management Agency's Flood Insurance Rate Map. This zone can experience a 100 year flood to a depth of less than one foot. The berm surrounding the ponds is elevated four feet above the adjacent grade and will protect the ponds from a one foot flood depth. 10. San Joaquin County Service Area No. 15 is in Section 30 , T2N , R6E, MDB&M, with surface water drainage to Calaveras River, as shown in Attachment A, which is attached hereto and part of the Order by reference. 11. The Board adopted a Water Quality Control Plan, Second Edition, for the Sacramento - San Joaquin Basin (hereafter Basin Plan), which contains water quality objectives for all waters of the Basin. These requirements implement the Basin Plan.