ARCHIVED REPORTS_XR0013076 - Laserfiche WebLink

Home Browse Search

M"AWArWAr4 ► Working to Restore Nature well MW-1 was dry during two sampling events: Cumulative results of groundwater samples are presented in Table 3. Source Removal Because the .two 1000-gallon gasoline tanks were removed:and approximately 500 cubic { yards of impacted soil was. removed.during soil excavation, it'appears there are no ongoing onsite sources of petroleum hydrocarbons that could affect soil or groundwater at this site. Approximately 623 pounds of TPHg were removed during_soil excavation: ASU -the the average concentration for TPHg at 10,000 ppm. . TPHg = 375 mg/kg X 1x10 kg/mg X 13,500 ft3 X.123 lb,/ft3 622.69 lb 'of gasoline JUSTIFICATION FOR CLOSURE It is 'RESNA'Sr opinion that adequate site investigation and remediation have been performed and the soil and groundwater conditions-at the .site warrant case closure. This ist based on the following. o Ongoing sources of hydrocarbons have been removed. from -the site. Approximately 500 cubic yards of impacted soil were removed(approximately 623 pounds of gasoline). o Approximately 0:006, 0.05, 1.53 and 2.49 pounds of benzene, toluene, ethylbenzene, and total xyienes, respectively, remain in soil in the vicinity of the former tank cavity between 15 to.40 feet bsg. o Groundwater monitoring was,performed for .an appropriate amount of time to adequately document site conditions,..and one monitoring well has been downgradient.of the former.gasoline tanks. -Groundwater beneath the site is not currently affected by hydrocarbons,. and TPHg and BTEX concentrations .have been below detection limits for four consecutive quarters. The direction of..groundwater flow has been consistently to the southwest to northeast with the exception of the first groundwater sampling conducted in July 1993 (gradient-toward the south). o The depth to groundwater has fluctuated between 86 to 88 feet below surface grade. 0504gtak/123009.01 5