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Protect No 014-95262 Page No 13 would explain how chloride could concentrate to the value noted If a floor is not present, a deeper soil boring at this location is necessary to determine the vertical extent of chloride in soil To prevent further addition of chloride to soil in the vault, the vault should be removed or sealed The probable source for the chloride, spillage during filling of the brine tank, should be corrected by prevention and/or secondary containment i 8.4 BdUe Spill Area Results of soil and groundwater data at the location of water sampling location KHP-1 and exploratory soil boring KB-1 suggest chloride from brine spillage, by runoff across the driveway surface and percolation into the soil, has reached groundwater Another possible source for chloride in groundwater is from spillage into the concrete-walled vault (discussed above) and infiltration to groundwater The concentrations in the groundwater sample are lust below the secondary Maximum Contaminant Level (MCL) for chloride (250 mg/L) and are above the secondary MCL for EC (900 µmhos/cm) Due to the high leaching potential for chloride in soils, a mitigative measure for this area may be . to cap the affected soil zones (e g , with asphalt) to prevent further leaching Prevention of further spillage s through modification of procedures or construction of secondary containment, and modification of the vault as noted above, is recommended 8.5 Wastewater Treatment Pond and Plan] Area Information from exploratory soil borings adjacent to the pond suggests elevated chloride is present at a depth of 15 feet bgs in boring KB-3 Nitrate was also elevated in the 20 feet bgs soil sample from boring KB-4, although it was equivalent to the possibly anamalous rutrate concentration in the 20 feet bgs sample from "background" soil boring KB-2 (see discussion in Section 7 2 2) Observations of soil moisture content during advancement of the soil borings suggests possible leakage from the pond The sample from a depth with 15 feet from borings KB-4 was moist At other locations it was generally the bottom-most samples (at 20 or 25 feet bgs) which were moist due to proximity of the water table at the tune of sampling (=25 feet bgs) Groundwater samples KHP-3, KHP-4, and KHP-5 from the vicinity of the pond all exceed the recommended secondary MCL for EC (900µmhos/cm), two of these samples exceed the upper limit MCL for EC (1,600µmhos/cm) Chloride in these samples ranged from 240-470 mg/L, two samples exceeded the secondary MCL for chloride (250 mg/L) KRAZAN& ASSOCIATES, INC Offices Semng the Western United States 95262 P52 i