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CLEANUP AND ABATEMENT ORDER -2- PIONEER AMERICAS,INC. PIONEER CHLOR ALKALI COMPANY,INC. ALL PURE CHEMICAL COMPANY SAN JOAQUIN COUNTY 6. On 28 January 1988, Board staff inspected the All Pure facility. Water riple `'colI;e from two of the wastewater ponds contained 120 ppb chloroform, 4.3 to 7.5: pb carbo tetrachloride, and other volatile organic compounds (VOCs). 7. The Discharger submitted a 26 July 1989 report entitled Technical Re �r�'dnd Assessmeht o S- oil and Ground Water Contamination. The assessment inel�:died:collecting six s' and five wafer samples from five boreholes along the fence line east: f the wa iewater ponds andiadditi.onl soil and groundwater sampling in three boreholes west df the-ponds. .separate plumes were identified: a plume of purgeable and extractableh iroc:a:t. s along>the eastern property line and a plume of chloroform north and west of the hydrockbon plume. N: VOCs were detected in the two onsite production wells. 8. In October 1989, the Discharger installed and sampled four moniibk ng wells(Figure 2). Chloroform was detected in three of the monitoring wells and carbdt tet'a:chloride was detected in one well. Since quarterly monitoring began n 1X913;; chloroform aritti`carbon tetrachloride concentrations have been as high as 4,0(30µg/I and 3`TQl.,g/l, respectively. Low concentrations of other VOCs also are present in three otl `mezitoring wells; 9. The regional flow direction in the sh 0 g:-oui tiwalpr is.td1he northeast. The shallow groundwater has consistently been shown t floe:southwest' at the All Pure facility since monitoring began in 1991.,;The,anomalouslow diren at All Pure may be due to leakage from the ponds and the resultir'g groundwater moiati.izig<='" 10. Board staff completarepotitled Tracy Well Survey Report on 28 December 1995. The Board survey iderlfied All' ?;pre as a likely source of chloroform and carbon tetrachloride in domestic wells north of the AIf`V-ure;facility. Staff recommended delineation of the nature and extent of carbon tieta"C"Woride andchlcoform plumes beneath All Pure. >bischatg7s from the facilit have used groundwater contamination onsite and offsite to the northeast. 12. ::<:In January and 1V&"1996 staff sampled water from the five ponds at All Pure. Chloroform and carbon tetrachloride were detected at concentrations up to 438 and 196µg/l, respectively. Thighesti< oncentziions were detected in the two lined wastewater ponds. During these samplrg.eytnts' hypalon liners in the two wastewater ponds were observed to be in poor condition, witlk<several large tears observed along the sides and bottoms of the ponds. The '` rmwater pard and the pond used for storage of water containing a high iron content were not 13. The primary maximum contaminant level for drinking water for carbon tetrachloride is 0.5 µg/l. The U.S. EPA Integrated Risk Information Service(IRIS) one-in-a-million incremental cancer risk estimate for drinking water for chloroform is 6µg/l. The Proposition 65 Regulatory Level for chloroform is 10µg/1.