| OCR Text |
Show C-Extension a has clay lined bottom and embankment It southeast of Pond C and occupies is located to the 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 the located west tailings impoundment and It Railroad tracks. Union Pacific north of the immediately of an constructed was 14 and acres occupies approximately the capacity of the In 1993, earthen dike with a clay core. pond was increased by raising the height of the embankment. A Claymax liner was placed on the interior slopes and keyed Pond D is currently in use into the initial dike clay core. Pond and is D contains an estimated 326,000 wet tons of sludge. from the mid-1989 resulted Low-lime Noranda sludge neutralization process which reduced the pH from 12 to 10 to improve control of the pH in the final effluent. The addition The sludge is of ferric chloride was resumed in August 1991. stored in Ponds B, C and D. In addition to the WWTP sludge, contaminated 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 hazardous identified most selenium are the commonly substances. Concentrations of lead range from several_ hundred parts per million to greater than 60,000 mg/Kg; arsenic was found a s. high as 50,000 mg/Kg with average concentrations between 20 and 1,200 mg/Kg, and selenium was found as high as mg/Kg with' average 7,300 mg/Kg. II. Further concentrations definition of these under the Work Plan developed for the of ,structures, areas not PURPOSE - some are between 5 shall performed areas Site. be and 700 Until demolition yt available for sampling. OVERVIEW This Statement of Work defines the objectives and scope of is irivolved 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 in surface impoundments, soil/debris stored on Site, and demolition of structures. In addition, site investigation 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 substances at levels of concern to ground water. work that . 2 |
