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Region 5,No Further Action - 6, U 10 October 1996 DRAFT DRAFT DRAFT DRAFT DRAFT DRAFT DRAFT DRAFT L At times, petroleum hydrocarbon discharges to surface waters occur j from nearby ground water seeps or fuel saturated soils. Such discharges are prohibited and must be stopped and prevented from recurring. Until the discharge to surface water is stopped, the site will not be considered for "low risk" designation. L4. The total pollutant mass remaining in the ground water is decreasing at predicted rates and neither creates, nor threatens to create, a risk to human 'i L health and safety or future beneficial use(s) of the aquifer Fate and transport modeling, (including breakdown rates and travel distances; risk based corrective action data and tests, and petroleum C L hydrocarbon breakdown products resulting from active or passive remediation), may be included in the rationale for determining that . the case is 'low risk The rates predicted must be verified with I L sufficient monitoring. L MANAGEMENT STRATEGY The existing and potential impact of leaving pollutants in aquifers designated for 1 Municipal beneficial uses must be determined by completing a site characterization, 3� remediation and monitoring program. !The determination must demonstrate to the I lead agency that, at''a minimum, by the time the ground water is anticipated to be used, water quality objectives will be achieved and beneficial uses will'be protected. The Responsible Party must provide sufficient evidence and rationale to show that L the remaining petroleum hydrocarbons may be loft in place and are in compliance ` L with applicable statutes, regulations, plans and policies. Documentation of results must be provided in accordance with Appendix B to the Tri-Regional Recommendations. A NFAR letter be issued only when the above work has been completed and site characteristics are shown to meet or exceed the above criteria. With few exceptions, all wat for the highers of the Central Valley.are designated in the'Basin Plans est uses requiring protection`and remediation; i.e. municipal and domestic supply. For these reasons it is imperative that pollution sites be adequately Lcharacterized and remediated as appropriate to protect ground water for its designated E+ beneficial uses. From a water quality perspective, the main goal of remediation is the LLrestoration of the beneficial uses of the water within a reasonable period of time, i.e., by the time the water has the probability of being used. To restore beneficial uses, ` cleanup must at least achieve water quality objectives (limits prescribed in the Central Valley Regional Water Quality Control Plans for the reasonable protection of i L beneficial uses). Staff considers economic and technical feasibility constraints for remediation alternatives for protecting waters for their existing and future beneficial uses. Therefore, it is necessary to determine when petroleum hydrocarbons in the ' environment can be considered or achieve a "low risk" status to remain in place f L Ia