WORK PLANS - Laserfiche WebLink

Home Browse Search

30 January 2014 AGE Project No , 99-0682 Page 10 of 28 Utilizing VW-2 ( UST area) as a mid-point, the lateral extent of TPH-impacted soil in the 60 to 100 foot zone appears to extend approximately 17 feet to the north , 44 feet to the northeast, 10 feet to the south , 25 feet to the east and 16 feet to the west (Figure 7). Vertically, the extent of TPH-impacted soil appears to be defined on the site . Generally, the vertical extent of petroleum-impacted soil extends to approximate depths between 90 and 100 feet bsg beneath the former UST area (Figures 3 and 4) , but attenuates significantly with depth . Figures 3 and 4 depict selected soil sample locations and the estimated extent of TPH-g concentrations adsorbed in soil in cross sectional view; Figures 5 through 7 depict the estimated lateral extent of TPH-g in plan view. When this data is plotted in both plan view and cross sectional views, the apparent volume of the petroleum hydrocarbon-impacted soil yields approximately 13, 705 pounds of TPH-g , which is equivalent to 2, 192 gallons of gasoline . Mass/volume calculations are included in Appendix C . 6.0 . GROUNDWATER MONITORING AND SAMPLING PROGRAM Between June 2000 and March 2013 fifty-six (56 ) groundwater monitoring events were performed at the site to monitor dissolved petroleum hydrocarbon concentrations in groundwater and to characterize groundwater flow direction and gradient on the site . 6 . 1 . GROUNDWATER LEVEL, FLOW DIRECTION AND GRADIENT Q,� ! ( " groundwSince aoterhasation frangedgroundwater betwe n25monitoring 33program tsite 00depth feet bsg . units generally flows to the east/northeast at relatively flat hydraulic gradients. Maps 1 illustrating the most recent groundwater flow directions and gradients , which include rose khA!� diagrams illustrating historic flow directions, in the shallow and intermediate screened wells o are included as Figures 8 and 9 . 6 . 2 , DISSOLVED PETROLEUM HYDROCARBON CONCENTRATIONS Results from periodic groundwater monitoring events indicate thatthe primary groundwater impact at the site consists of TPH-g , TPH-d , BTEX, TAME , EDB and 1 ,2-DCA. Historically, the most intense hydrocarbon-impact in the shallow groundwater at the site (25 to 50 feet bsg ) has been detected from well MW- 1A and boring B- 1 ( Figures 10 , 11 and 12) . Additionally, elevated hydrocarbon impact has been detected in intermediate groundwater Advanced GeoEnvironmentnl, Inc.