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CLEANUP AND ABATEMENT ORDER NO.R5-2006-0720 NESTLE USA,INC. RIPON, SAN JOAQUIN COUNTY Also, during April and May of 2005, the Discharger pumped and treated an average of approximately 64 gpm from Industrial Avenue extraction well EI-1, but stopped due to high total dissolved solids(TDS)concentrations in the effluent. Apparently, groundwater cannot be pumped from the existing Industrial Avenue extraction wells at rates above approximately 10 gpm without causing a TDS excursion above the City of Ripon's water quality limit for the non-potable water systema The existing extraction wells at the Industrial Avenue Facility are capable of sustaining extraction rates much higher than 10 gpm, but corrective actions have not been implemented to improve pump and treat operations even though the Discharger is permitted to discharge up to 220 gpm to the City of Ripon's industrial sewer. As an interim remedial action,the Discharger needs to immediately increase pumping rates in existing Upper Aquifer extraction wells at the former Facility to design rates or to the maximum discharge rate permitted to the City of Ripon's industrial sewer. Also,the Discharger needs to implement a long-term solution to disposal of treated groundwater that may contain elevated total dissolved solids, nitrates, or other naturally occurring or anthropogenic constituents that cannot be discharged to the industrial sewer system or non-potable water system. 10. Since 1986, the Discharger has installed more than 98 groundwater monitoring wells on-and off-site to delineate the VOC contamination believed to be associated with the Facility("TCE Plume"). The Discharger has also conducted quarterly groundwater monitoring since 1986. In November/December 2000 the Discharger installed guard wells to provide early detection of VOCs migrating to municipal wells MW-3, MW-7,MW-9, and MW-10 as well as Fox River Paper Company supply wells PW-6, -7, and—8 (Figure 3). 11.The extent of the TCE plume appears to be defined west, north,and east of the Facility in the Upper and Intermediate Aquifer Zones. The plume has migrated southward and beneath the Stanislaus River. It is uncertain how far the plume has migrated west of monitoring well cluster M-32, which is located adjacent to the north side of the river. An additional well cluster located west of monitoring well M-32 is needed to complete delineation of the southern extent of the plume. Based on recent monitoring data, the plume appears to be migrating vertically from the Intermediate Aquifer Zone into the Lower Aquifer Zone. The Discharger has installed seven (7)Lower Aquifer Zone monitoring wells on the north side of the Stanislaus River,which is now considered inadequate to detect vertical migration from the Intermediate Aquifer and potential migration towards the City of Ripon's supply wells. Recently, significant increasing TCE and cis-1,2-DCE trends and the maximum historical concentrations of these contaminants have been detected in Lower Aquifer monitoring wells M-613 and M-81),which are located beneath or adjacent to the Discharger's TCE source areas. TCE and/or its degradation products have also been detected in 5 of the 7 Lower Aquifer wells in the past 18 months and Regional Board staff disagree with the Discharger's interpretation that these are isolated detections in the Lower Aquifer Zone. Regional Board staff believes these detections may be part of a continuous plume in the Lower Aquifer Zone and the Discharger needs to delineate the Lower Aquifer plume, install an adequate monitoring network, and implement remedial actions to capture and prevent further migration of the TCE plume in the Lower Aquifer Zone. The City of Ripon recently installed drinking water supply wells MW-13 and MW-14, but the Discharger's monitoring network is unlikely to provide early detection of plume migration towards 3