SU0006159 - Laserfiche WebLink

Home Browse Search

1 .Or WASTE DISCHARGE REQUIREMENTS BROWN SAND INC. AND MOSSDALE ASSOCIATES, LTD. MOSSDALE RANCH AGGREGATE SAND EXCAVATION AND PLANT SAN JOAQUIN COUNTY -2- 7. Excavated sands will be processed at the plant by washing and screening. It is anticipated that less than 3% of the raw feed will be wasted as fines. Fines from the processing operations will be contained on site by using a process-water sedimentation/recycle pond. The pond will be designed and operated to provide containment from overflow for all washwaters and stormwater generated during a 24-hour storm event with a return frequency of 100-years . A coagulant (NALCO 8852) and a flocculant (NALCO 9810) will be added to the washwater at concentrations of 1 .5 ppm and 3 .0 ppm, respectively. It is estimated that 200 tons per day of fines will be generated during site operations. Fines will be periodically removed from the recycle pond and placed next to the pond for decanting. Ultimate deposition of the fines will be next to the excavation area or sold. See Attachment B for the process flow diagram, incorporated herein and made part of this Order. 8. The washwater may eventually be discharged to the dredge pond, with the elimination of the sedimentation/recycle pond. Elimination of the coagulant and flocculant would also be considered at that time. GEOLOGY AND HYDROGEOLOGY 9. On-site testing and drillers logs from the immediate vicinity of the site indicated that relatively clean fine to course grained sands are present between 10 and 50 feet below ground surface. The sand is comprised primarily of angular quartz with varying amounts of feldspar, heavy minerals, and rock fragments. Below the sands is a clay unit that ranges between 20 and 60 feet in thickness. Operations will not extend into this clay unit. 10. Ground water is presently found 10 to 15 feet below ground surface. Wells in the area obtain their water from below the clay unit, at depths greater than 100 feet. Seepage from the sedimentation/recycle pond will infiltrate into the shallow ground water unit. In addition, the dredging portion of the operation will operate a dredge that is floating on the excavation impoundment which is directly connected with the shallow ground water. 11 . The Discharger has installed a ground water monitor well in the upper water bearing zone. Initial sampling of the ground water has found the pH to be 8.0 and concentrations of TDS of 985 mg/1 , chlorides of 262 mg/1 , iron of 10.75 mg/1 , and manganese of 1 . 25 mg/1 . The iron and manganese concentrations are above their respective Secondary Drinking Water Standards of 0.3 and 0.05 mg/1 . OTHER 12. The Board adopted The Water Quality Control Plan, 2nd Edition, for the San Joaquin Delta Basin (5B) which contains water quality objectives. These requirements are consistent with that Plan.