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Ripona Market October 28,2004 Corrective Action Plan northeast trending eclipse approximately 20 feet by 13 feet (Figure 7 ) MTBE contamination was detected in soils excavated during the UST removal I3.5 Contaminant Receptors I There are two municipal and domestics wells that could possibly be impacted by the release The nearest down gradient well, Well #5 is located approximately 1000 feet to the northeast An up gradient well, Well 2S/8E/19F is located Iapproximately 500 feet to the southwest 3.6 Proposed Clean Up Levels The Central Valley Regional Water Quality Control Board has provided guidance on appropriate cleanup levels for impacted groundwater in the 2003 "Compilation Iof Water Quality Goals"which states 1 Groundwater shall not contain chemical constituents in concentrations I that adversely affect beneficial uses 2 Groundwater designated for use as domestic or municipal shall not contain concentrations of chemicals in excess of the maximum contaminants levels stated in Title 22, CCR 3 Groundwater shall not contain taste and odor producing substances in concentrations that cause nuisance or adversely affect beneficial uses 4 Groundwater shall remain free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life Drinking water standards are established as maximum contaminant levels (MCL) by the Department of Health Services for potable water Maximum contaminant levels for volatile aromatics are Benzene 1 ug/l/Prop 65 level 0 35 ug/l Ethyl Benzene 700 ug/l Toluene 150 ug/l Xylenes 1750 ug/l Taste and odor thresholds have also been considered as clean up goals for domestic or municipal beneficial uses Taste and odor thresholds Taste and odor levels for volatile aromatics, MTBE, and petroleum hydrocarbons are Benzene 170 ug/1 Ethyl Benzene 29 ug/l Toluene 42 ug/l Xylenes 17 ug/1 Gasoline 5 ug/l MTBE 5 ug/l I 8 r