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Mr. Maurice Benson <br /> February 3, 2003 <br /> Page 2 <br /> Specific Comments: <br /> 1. Page ES-1, section ES.2.2; This section discusses that ground water (GW) <br /> elevation contour maps were not developed for the D-zone because only eight <br /> wells are screened in this zone and widely spaced across the installation. Please <br /> restate that there were insufficient data points in the D-zone due to the widely <br /> spaced wells across the installation in order to generate a GW elevation contour <br /> map. <br /> 2. Page ES-1, section ES.2.2; This paragraph mentions "GW north of the site was <br /> flowing southwest toward the depression west of the North Balloon area." Please <br /> elaborate on the depression (i.e. lithology, GW elevation, etc,). <br /> 3. Page ES-5, section ES.4.9, last sentence; Please describe in the report why the <br /> significant statistical trends were not supported by an evaluation of the time <br /> series plots. <br /> 4. Page ES-7, section ES.5.5, If extraction well EWCC3 is "critical to the hydraulic <br /> control of the off-depot Trichloroethene (TCE) plume" in the CA, then it is <br /> probably safe to say the inconsistent operation of EWCC3 "is" responsible for the <br /> migration of the plume, rather than "may" be responsible. Please make the <br /> necessary changes to this section of the report. <br /> 5. Page ES-8, section ES.6.5; This section states that MW527A "should be <br /> replaced with a well that has a deeper screen interval." Please be more specific <br /> in the report in identifying the screen interval deemed necessary in order to <br /> record any water level measurements. <br /> 6. Page 3-3, section 3.3.3, last sentence; This last sentence is misleading by <br /> implying that the Mann-Kendall is used to show analytical variability rather than <br /> real concentration ranges. Please rephrase to "In this case, although statistically <br /> significant, probably do not indicate real concentration changes." <br /> 7. Page 3-20, figure 3.4-2; This figure shows the error for wells in 2002 is much <br /> higher than any of the previous year's error. Please provide an explanation at <br /> either the bottom of the figure or in the recommendations and conclusions for the <br /> uncharacteristically high error. <br /> 8. Page 4-4, section 4.2.5.2; Please discuss in the report what actions are planned <br /> to prevent chromium in soil from leaching into the groundwater in the SB. <br />