ARCHIVED REPORTS_2011 REVISED FEASABILITY STUDY

Home Browse Search

Nestle USA, Inc.—Ripon, CA January 28, 2011 2011 Revised Feasibility Study concentrations beneath the Site. Biosparging costs are estimated to be approximately $86,500,000 for treating groundwater in the vicinity of the WWTP (Attachment 113.1). 9.3.2.6 Conclusion In-situ chemical/biological technology is retained for further evaluation for reducing or removing CDCs beneath the Site within the Upper Aquifer. 9.3.3 Intrinsic Remediation Intrinsic Remediation (IR) is the reliance on natural abiotic degradation or biodegradation to reduce COC concentrations in soil and groundwater. By definition, these processes are passive, but can be greatly influenced by local activities or outside influences to the otherwise natural system (such as enhanced redox gradients due to changes in pumping, or enhanced biodegradation due to the recharge of oxygen rich or organic and/or nutrient rich water). IR typically involves sampling and documentation of information such as chemical trends, geochemical indicators, isotope analyses, and microbiological studies to develop multiple lines of evidence indicating that COC destruction is occurring in-situ, due to natural chemical or microbiological conditions within the aquifer system. . Attachment B.4 provides a detailed assessment of the application of IR to the Study Area. 9.3.3.1 Effectiveness IR may be a slow process but it can be combined with other remedies to form a more effective final remedy. An interim IR study was conducted in 2010 to document the occurrence and rate of intrinsic remediation occurring at areas of VOC impacts across the Study Area (Attachment 13.4). As detailed in Attachment 113.4, IR has resulted in substantial COC destruction to date, and its effectiveness across the Study Area will be enhanced in conjunction with other COC treatment alternatives. 9.3.3.2 Implementability Because IR relies on natural processes, it can be readily implemented. A large network of monitoring wells exists in the Study Area and at the Site, therefore, IR is implementable. This monitoring well network would facilitate the monitoring of the IR process, although the network and sampling program should be assessed for the most efficient evaluation of IR progress. Implementing this technology would require gathering additional data to develop lines of evidence that IR is occurring followed by periodic assessment of the monitoring and sampling results. A detailed assessment of IR, and its feasibility within the Study Area, is included in Attachment 113.4. 9.3.3.3 Relative Cost The cost for IR is minimal compared to all other long-term technologies. Typical costs could be on the order of $200,000 for the initial monitoring program, 36