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U.S. ARMY ENGINEER SACRAMENTO DISTRICT CORPS OF ENGINEERS <br /> DESIGN REVIEW COMMENTS Project: _CA ARNG Site Investigations—Stockton AASF <br /> ❑ SITE DEV&GEO ❑ MECHANICAL ❑ SAFETY ❑ SYSTEMS ENG REVIEW Final Work Plan—Former USTs <br /> ❑ ENVIR PROT&UTIL ❑ MFG TECHNOLOGY ❑ ADV TECH ❑ VALUE ENG DATE 27 July 2007 <br /> ❑ ARCHITECTURAL ❑ ELECTRICAL ❑ ESTIMATING El OTHER <br /> ❑ STRUCTURAL ❑ INST&CONTROLS ❑ SPECIFICATIONS NAME Marcus Pierce—RWQCB <br /> DRAWING NO. <br /> ITEM OR REFERENCE COMMENT ACTION <br /> 3. In several sections of the Work Plan,CA ARNG implies that the 2004 Work Plan text has been revised to state that the 2004 <br /> investigation defined the lateral extent of soil contamination south and southeast investigation did not determine the lateral extent of <br /> of the former 5,000-gallon and 20,000-gallon USTs.The three borings(B-1,B-2, contamination resulting from leakage from the former <br /> and B-28)advanced during this investigation provide information on potential 5,000-gallon USTs,but did provide partial lateral extent <br /> leakage south and southeast of the former 20,000-gallon USTs,but are more than determination to the south and east of the former 20,000- <br /> 100 feet from the former 5,000-gallon USTs.The 2004 investigation does not gallon USTs. <br /> provide useful information on the lateral extent of contamination resulting from <br /> leakage from the former 5,000-gallon USTs. Revise these sections to clarify the <br /> 2004 investigation provides information on the lateral extent of contamination <br /> resulting from leakage from the former 20,000-gallon USTs only. <br /> 4. CA ARNG should sample the three existing monitoring wells as part of the The Work Plan has been revised to include groundwater <br /> investigation proposed in the Work Plan.These wells have only been sampled sampling of the three existing monitoring wells. <br /> twice in the past seven years and have not been sampled since March 2004. <br /> Specific Comments <br /> I. Page 3,Section It is misleading to conclude that the site groundwater table is flat.There is a The work Plan text has been revised to state that the <br /> 1.4.2 measurable gradient of 0.004 foot/foot.Also,there are only three monitoring wells groundwater gradient calculations based on only three <br /> at the AASF and these wells are closely spaced,so any conclusions drawn on closely spaced wells cannot be accurately measured. <br /> local gradients should be qualified.Revise the Work Plan accordingly. <br /> The groundwater gradient was determined to flow north.The reference for this Text has been revised to state that the conclusion that <br /> information is"Hilyard,2007'.The Work Plan should be revised to indicate this groundwater flows to the north is based solely on <br /> conclusion is based on the historical groundwater measurements collected by CA historical groundwater measurements collected by the C. <br /> ARNG from the three AASF monitoring wells and reviewed by the author of the ARNG from the three AASF monitoring wells. <br /> Work Plan(URS)rather than implying CA ARNG says groundwater flows north. <br /> CESPK FORM 7 (Revised) PREVIOUS EDITIONS OF THIS FORM ARE OBSOLETE PAGE 2 OF t <br /> 15 Apr 89 <br />