Laserfiche WebLink
S M1 <br /> 1 <br /> 1 S I t y 1t <br /> 08 December 2000 <br /> AGE-NC Project No 95-01'03 <br /> Page 3 of 5 " <br /> ' 3 1 GROUND WATER ELEVATION <br /> Depth to ground water ranged from 11 32 to 13 55 feet below the top of the well casings Ground <br /> water elevation decreased approximately 1 42 feet between the July 2000 and November 2000 <br /> ' monitoring events The ground water flow direction ranged from the southeast to northeast in the <br />` area of the former USTs The average hydraulic gradient was 0 006 ft/ft Figure 3 depicts the ground ` <br /> ' water"elevation contours at the site , <br /> s <br /> 3 2 GROUND WATER ANALYTICAL RESULTS , <br /> 1 <br /> ' TPH-g was detected in samples from monitoring wells MW-1, MW-3, MW-4, MW-5, and vapor <br /> wells VE-1 and VE-6 at concentrations of 5,700 microgramper liter(gg/1),7,500 µg/1,480 µg11, 600 <br /> gg/l, 2,000 gg/1 and 8,700 gg/l, respectively <br /> r <br /> Benzene was detected in five of the water samples(samples MW-1,MW-3, MSV-4, VE-i and VE-6) <br /> at concentrations ranging from 39 gg/l in well MW-3 to 1,400 gg/l in well VE-6 The remairimg <br /> lieBTEX compounds (toluene, ethylbenzene and,xylenes) were detected in samples MW-1, MW-3, t <br /> MW-4,MW-5,MW-6;VE-1 and VE-6,,with the highest concentrations occurring in samples MW-4 <br />` and VE-6 <br /> MTBE was d6tected in the water sample from well MW 1 at a concentration of 25 gg/l DIPE was <br /> detected in samples MW-1, MW`3, MW-5, VE-1 and VW-6 at concentrations as high as,51 µg/1 <br /> ' TBA was detected in samples MW-1,MW-3 and VE;1 at 69 gg/1; 22 gg/l and 41 gg/l, respectively <br /> The analytical results of current and previous monitoring well samples are summarized in Tables <br /> ' 2 and 3 The laboratory report of the currentground water sampling data(MAI sample ID,Numbers <br /> ' 52152 through 52159), quality assurance and quality control (QA/QC) data and'chain-of custody <br /> form are included in Appendix B - <br /> a <br /> 33 IN-SITU AIR SPARGING/SOIL VAPOR EXTRACTION <br /> Elevated concentrations of dissolved oxygen were detected in the ground water samples from <br /> ' monitoring well MW-4, vapor extraction well VE-3 and air sparging observation wells ASO-1 and <br /> ASO-2 <br /> Over the last quarter of air infection, the' dissolved oxygen concentrations for wells ASO, M <br /> 1, W-4 and VE-3, were measured as high as 76 3%, 52 9% and 41 8%, respectively(07 September 2000) <br /> . Wells MW-1, VE-1 and VE-6 had lower dissolved oxygen concentrations of 13 1%, 22 6% and . <br /> ' 14 1%, respectively (Appendix C) Spargmg rates were measured at approximately 10 scfm during <br /> Advanced GeuE.vironmental,Inc <br /> i <br /> r - I <br /> L <br />