ARCHIVED REPORTS_XR0002784 - Laserfiche WebLink

Home Browse Search

. 2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On February 12, 1998, Ramage Environmental monitored and sampled groundwater at the site 21 Groundwater Monitoring were taken in all five groundwater monitoring wells except Depth-to-groundwater measurements MW-1 and the two deep soil vapor extraction wells (VW-1 and VW-2) to evaluate groundwater ' flow and gradient characteristics Monitoring Well MW-1 was inaccessible due to flooding The depth-to-groundwater beneath the site ranged from 44 72 feet below ground surface (bgs) in MW-4 to 45 56 feet bgs in MW-5 The groundwater elevation beneath the site ranged from 27 53 feet below mean sea level (MSL) in MW-4 to 27 35 feet below MSL in MW-3 Groundwater levels have risen an average of 3 52 feet since groundwater levels were last measured on November 13, 1997 In the past year, groundwater levels have risen an average of 1 35 feet Since May 1992, the groundwater levels have risen 21 84 feet The historical groundwater monitoring data are summarized in Table 1 The groundwater flow direction and gradient are illustrated on the groundwater surface map (Figure 3) In general, the groundwater gradient was calculated at 0 0021 footifoot in a north- northeast direction Because groundwater levels in the five groundwater wells are above the screened interval, the calculated flow and gradient characteristics may be unreliable The groundwater flow and gradient calculations do not utilize groundwater levels in the sod vapor extraction wells because their wellhead elevations have not been surveyed 22 Groundwater Sampling and Analysis Groundwater from the deep sod vapor extraction wells (VW-1 and VW-2) was sampled to evaluate the concentration of gasoline hydrocarbons at the groundwater table The groundwater monitoring wells (MW-1, MW-2, MW-3, MW-4 and MW-5) were not sampled because of groundwater levels significantly above the screened interval of these wells The deep soil vapor extraction wells (VW-1 and VW-2) were purged of at least three well volumes using a decontaminated bailer Following purging, groundwater samples were collected from the two wells using a disposable sampling bailer The groundwater samples were contained in laboratory-supplied glassware, labeled, sealed in a plastic bag and packed in an 2