SU0003074 ENG DES PLN - Laserfiche WebLink

Home Browse Search

development is restrained, and the 5 feet separation distance from the bottom of the _ percolation pond can be maintained during extremely wet hydrologic conditions. Without groundwater level data available on a monthly or at least quarterly basis, it is difficult to predict the average annual pumping which will be required over a long period of time. However, it can be said with confidence that the amount of discharge to the river under this proposal would be significantly less than by direct discharge, due to the ability to assimilate the effluent into the underlying groundwater. The sewage treatment plant effluent will be highly treated; however it is expected that the groundwater discharge, an indirect discharge of the percolated sewage effluent to the San Joaquin River, will be of better quality than the sewage effluent. Therefore, under this proposal, not only will the quantity of water discharged be less than under a direct disposal scheme, but the quality of the water so discharged will also be better. Discharge of the wells into the San Joaquin River will require a Waste Discharge Permit issued by the Regional Water Quality Control Board and appropriate monitoring requirements. The application for waste discharge will further examine the issue of water quality by reviewing the expected quality of the effluent, the ambient groundwater quality, and the water quality of the San Joaquin River. Due to the expected good quality of the effluent and the underlying groundwater, it is anticipated that discharge standards will be met. V. CONCLUSIONS AND RECOMMENDATIONS To optimize pond performance it is recommended that two wells approximately 60 feet deep be installed to discharge to the San Joaquin River. Having the deep wells in place will mitigate any impact on Oakwood Lake and add reliability to the disposal system. It must be recognized that while sophisticated modeling techniques were utilized to simulate transient groundwater conditions, there is always a degree of uncertainty, and the performance of the ponds may be slightly better or slightly worse than predicted APRIL 1994 CCIP/SIMULATION OF PERCOLATION POND PERFORMANCE PAGE 8