| OCR Text |
Show a C-Extension has clay lined bottom and embankment It is located to the southeast of Pond'C and occupies slopes. 3.5 acres. Pond C-Extension began receiving sludge in the spring of 1992 and, reached capacity in 1993. This pond contains approximately 58,000 wet tons of sludge. Pond of located west the tailings impoundment and Railroad tracks. of Union It north· the Pacific immediately constructed of 14 was an acres and occupies approximately the capacity of the earthen dike with a clay core. In 1993, was the increased pond by raising height of the embankment. A Claymax liner was placed on the interior slopes and keyed into the initial dike clay core. Pond D is currently in use and contains an estimated 326,000 wet tons of sludge Pond is D Low-lime the from Noranda resulted mid-1989 sludge neutralization process which reduced the pH from 12 to.10 to improve control of the pH in the final effluent. The addition of ferric chloride was resumed in August 1991. The sludge is stored in Ponds B, C and D. In addition to the WWTP sludge, contaminaed soil/waste from the North facilities (Refinery, Concentrator and Smelter) and adjacent areas is included in the scope of this Action. There is an estimated 1.·0 million cubic yards of' soil/waste that contains hazardous substances. Lead, arsenic, cadmium and the selenium are most identified hazardous commonly substances. Concentrations of lead range from several hundred parts per million to greater than 60,000' mg/Kg; arsenic was found as high as 50, 000 mg/Kg with average concentrations between 20 and 1,200 mg/Kg, and selenium was found as high as 7,300 mg/Kg with average concentrations between 5 and 700 Further definition of these areas shall be performed mg/Kg. under the Work Plan developed for, the Site. Until demolition of structures, some areas are not yet available for sampling. II. PURPOSE - OVERVIEW This Statement work that of Work defines the objectives and scope of is involved in fulfilling the requirements of the Administrative Order on Consent (Docket # CERCLA VIII-95-04) The purpose of the work described herein is to develop and implement a response action to address the release or threat of release of hazardous substances at the Site. This includes the removal and disposal of Wastewater Treatment Plant sludge surface in impoundments, soil/debris 'stored on Site, and demolition of structures.' In addition, site Lnves t i qa t Lon activities shall identify those areas that may impact ground water; and, to the extent practicable, response actions will include measures to mitigate release of hazardous ubstances at levels of concern to ground water. . 2 |
