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28 May 1999 AGE-NC Project No 95-0128 Page 3 of 5 ' other wells monitored Ground water was inferred to be flowing approximately N 35°W in the properly screened wells(Figure 3)and N 20'W in the deeply screened wells(Figure 4) The gradient determined for the three drowned wells was approximately 0 001 ft/ft, the gradient for the four ' properly screened wells was approximately 0 002 ft/ft If the elevation data for all wells are contoured, contorted lines of equal elevation are produced, suggesting that either frictional forces cause different elevation data between the properly screened and deeply screened wells, or that the ' flow regime in shallow ground water is somewhat independent of the deeper ground water encountered on the site The same effects on ground water elevation were found in the data for the 31 December 1998 ground water monitoring event, as shown on maps included in Appendix D 1 3 2 ANALYTICAL RESULTS FROM GROUND WATER SAMPLES ' MAI received extracted and g analyzed the ground ound water samples on 23 March 1999 MAI issued a ' report dated 30 March 1999 The analytical results from the ground water samples are as follows • During the March 1999 ground water monitoring event, trace quantities of various BTEX compounds were detected in the ground water samples from the drowned wells MW1 and MW3,TPH-g and TPH-d were not detected in the samples Dissolved petroleum hydrocarbons were detected in all the properly screened monitoring ' welIs The highest concentrations of hydrocarbons were detected in the water sample from the vapor extraction well VW 1,which contained 23,000µg/1 TPH-g, 6,100,ug/1 TPH-d, 670 I ktg/l benzene, 3,000 ktg/l toluene, 1,100µg11 ethyibenzene and 5,100 /.cg/l total xylenes The lowest concentrations of hydrocarbons were detected in the sample from the up-gradient monitoring well MW7, which contained 0 73 ,ug/l benzene, 1 8 µg11 toluene, less than 1 1 ,ug/l ethylbenzene and 5 2 ,ugll total xylenes • The concentrations of dissolved petroleum hydrocarbons decreased an order of magnitude in samples from MW4 and MWS, and increased an order of magnitude in the sample from VW1 • TPH-d was detected in samples from all the properly-screened monitoring wells, except MW7, at concentrations as high as 6,100,ug/l (V W I), but was not detected in samples from ine deeper-screen weiis m w 1, M W 2 or M w3 I MTBE was detected in ground water samples collected from monitoring wells MW2 through MW7 and from vapor well V W l Detected concentrations of MTBE ianged from 5 5 ,ug/l (MW2) to 3 200 ,ug/l (MWS) • TAME was detected at 1 2 µg/l in the sample collected from the drowned monitoring well MW3 .4d►,anced CeoEn.fronmental Inc