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. Try Regional Recommendation Page 20 of 24 Appendix A groundwater to exceed water quality water quality objectives This may occur at sites objectives where hard to reach soil contamination remains beneath building foundations, and the 4 There are no existing water supply wells, contamination continues to leach to groundwater surface waters or other receptors threatened In these difficult cases, responsible parties may by the remaining contaminants in soil or argue that the incremental cost for further mass groundwater removal exceeds the incremental benefit 5 Pollutants remaining in groundwater do not Regional Board staff believe that in some cases it create or threaten to create risk to human is reasonable to issue a NFAR letter for sites that health and safety, or to future beneficial do not meet water quality objectives but present a use(s) of the groundwater Patterns of low risk and are expected to meet water quality existing and future demands for usable objectives in the near future To receive such case water resources in the area must be closure,responsible parties need to demonstrate considered in determining what period of that site contaminants are degrading, and that site time is reasonable to reach non-detectable contaminants will reduce to levels protective of (or background)concentrates beneficial uses in a reasonable period of time 6 The plume size is stable and sufficiently Numerical water quality limits for petroleum fuel limited in lateral and vertical extent and mixtures, constituents and additives, consistent contaminant concentrations detected in with applicable water quality objectives, are groundwater show a decreasing trend with available in the following staff document time One hydrologic cycle (four quarters) Beneficial Use-Protective Water Quality Limits of monitoring after active remediation for Components of Petroleum-Based Fuels This measures have ceased is usually considered document is updated regularly and available on 0 to be the minimum necessary to determine the Regional Board website at site groundwater and plume conditions http //www swrcb ca gov/rwgcb5/available_docu ments/index htm]#WaterQualityGoals Issuing NFAR letters for low risk cases is consistent with State regulations and policies Board staff are currently requiring the following The practice of closing low risk cases is also information to support requests to issue a NFAR consistent with the actions taken by the State letter at UST sites with contaminant Water Resources Control Board and Regional concentrations above water quality objectives Boards throughout the State 1 Demonstration that the plume is stable with 6 5 NFAR for Cases Exceeding Water Quality either an overall annual decrease in size or Obiectives an annual decrease in contaminant concentration trend The Regional Board and LIA staff are receiving more requests each year from UST owners or 2 Calculations or modeling results,including operators to grant closure of UST cases where monitoring verification of model groundwater has not attained water quality conclusions,which show when water objectives The responsible parties believe that quality objectives are predicted to be they have implemented reasonable cleanup and achieved abatement at these sites and that it is no longer technologically or economically feasible to 3 Verification that there are no current or continue corrective actions and monitoring anticipated uses of the impaired water within the timeframe projected to meet A common example is when remedial actions water quality objectives Institutional have reduced groundwater contaminants by a controls may be needed to prevent such use large percentage,but constituents still exceed if this period is not sufficiently short