2003-11-13_REVISION - M1992069 - Laserfiche WebLink

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Ms. Kate Pickford/DMG - F Street Groundwater Monitoring Plan Project Number 1001015 P!\R/1GON November 11, 2003 Page 2 • After dewatering ceases, monitoring of seven (7) wells will be performed on a weekly basis until the water table reaches approximately 4.5 feet below the pit floor since that is the approximate top elevation of the screened interval of the wells. Collecting groundwater samples when the water table is above the screen would not yield representative samples since the specific gravity of diesel fuel is less than one (1). The screened interval for the two (2) new wells will be approximately two (2) feet below grade which would allow for a longer monitoring period, if necessary. The wells which will be included in the weekly monitoring episodes are MW-1, MW-3, MW-4, MW-5, EW-1 and the two (2) new wells. Monitoring well MW-2 has apparently been destroyed. • Aggregate Industries has estimated that it will take approximately two (2) to three (3) weeks for the water table to rise to the existing pit-floor elevation after cessation of dewatering. If rebound of the water table takes longer than four (4) weeks to reach the top of the well screens, Aggregate Industries will contact the DMG with a request to modify the monitoring frequency. • During each of the previously described weekly monitoring events, the depth to groundwater in the seven (7) wells will be measured and groundwater samples will be collected from each well for chemical analyses. The groundwater samples will be submitted for laboratory analyses of benzene-toluene-ethylbenzene-xylenes (BTEX) and total petroleum hydrocarbons -diesel range organics (TPH-DRO). Aggregate Industries requests that total petroleum hydrocazbons -gasoline range organics (TPH-GRO) analyses not be required, as suggested by the DMG in the Inspection Report, since gasoline was not stored or released at the site. • The laboratory report for each sampling episode will be transmitted to the DMG by facsimile after receipt from the laboratory. Groundwater elevation data, piezometric surface diagrams and the laboratory results will be reported to the DMG in one (1) written report at the conclusion of the monitoring activities. If unusual data is observed during the monitoring activities (such as the presence of free-phase product or an exceedance of a Maximum Contaminant Level), the DMG will be notified and dewatering will resume in accordance with the parameters of the CDPES discharge permit. Obviously, if site conditions observed during the monitoring period warrant additional remediation, a Corrective Action Plan would be developed and submitted to the DMG for approval.