|
1 v
<br /> ATC
<br /> A S S O C I A T E S I N C .
<br /> ether (DIPE), tertiary amyl ether (TAME), tertiary butyl ether (TBA), 1,2-dichloroethane (1,2-
<br /> DCA), and 1,2-dibromoethane (EDB) utilizing EPA Method 8260B. Groundwater well purge
<br /> ' and sample logs are contained in Attachment 1.
<br /> 2.1 Groundwater Flow Direction
<br /> Water levels were measured in MWI through MWS, MW6a, MW6b, MW6c, MW7a, MW7b,
<br /> MW7c, MW8, MW9a, MW9b, MW9c, MW10a, MWIOb, MW10c and EW1 during the March
<br /> ' 16-17, 2005 monitoring event. The water level data were used to develop the groundwater
<br /> elevation contour maps for the shallow (A), intermediate (B), and deep (C) groundwater zones
<br /> ' (Figures 3 through 5).
<br /> MW1 through MW6a, MW7a, MW9a, MWIOa, and EW1 are screened in the shallow water-
<br /> bearing zone. During the March 16-17, 2005 event, water levels in these wells ranged from 64.82
<br /> ' to 65.80 feet below the tops of the well casing (TOC) elevation. Groundwater in the shallow
<br /> zone beneath the site flowed towards the South-Southeast during the March 16-17, 2005
<br /> groundwater-monitoring event. The average hydraulic gradient in the shallow water-bearing zone
<br /> during the March 16-17, 2005 monitoring event, was calculated to be 0.0001 ft/ft or
<br /> approximately 0.53 ft/mile.
<br /> MW6b, MW7b, MW9b and MWIOb are screened in the intermediate water-bearing zone. Water
<br /> levels in MW6b, MW7b and MW 10b ranged from 65.18 to 66.39 feet below TOC elevation.
<br /> ' Groundwater in the intermediate zone beneath the site flowed towards the Southeast during the
<br /> March 16-17, 2005 groundwater-monitoring event. The average hydraulic gradient in the shallow
<br /> water-bearing zone during the March 16-17, 2005 event, was also calculated to be 0.0001 ft/ft or
<br /> approximately 0.5 ft/mile.
<br /> MW6C, M47c, MW8, MW9c and MWIOc are screened in the deep water-bearing zone. Water
<br /> 1 levels in these wells ranged from 64.62 to 66.45feet below TOC elevation. Groundwater in the
<br /> deep zone beneath the site flowed towards the East-Southeast during the March 16-17, 2005
<br /> groundwater-monitoring event. The average hydraulic gradient in the shallow water-bearing zone
<br /> ' during the March 16-17, 2005 monitoring event was also calculated to be 0.001 ft/ft or
<br /> approximately 5.2 ft/mile.
<br /> A summary of groundwater monitoring data is presented in Table 1.
<br /> 2.2 Groundwater Analytical Results
<br /> The groundwater samples from MW2, MW3, MWS, MW6a and EWl contained detectable
<br /> concentrations of TPHg. BTEX constituents were detected in samples from MW2, MW3 and
<br /> EW1. None of the groundwater samples contained detectable concentrations of TPHd.
<br /> MTBE was detected in groundwater samples from MW1, MW2, MW4, MW6b, MW6c, MW7a,
<br /> MW7b, MW7c, MW i Ob and EW I. The groundwater samples from MW2 and MW6a contained
<br /> ' 5:1268231QM reports12005 lstQR.doc 3
<br />
|