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Y <br />Expect DIMP to be in the dissolved phase at these low concentrations (not floating or <br />sinking). <br />One is not likely to find DIMP in soils outside the Rocky Mountain Arsenal (RMA). <br />CDPHE-HMWMD. Federal Facilities, RMA <br />Ed LaRock, (303)692-3324 <br />Per an October 7, 2004 telephone conversation with Ed LaRock: <br />• Tri-County Health and the USGS (Nevi) Gaggiani 303-289-0346) produce two "exceedence" <br />maps every five years for the RMA. The last one was issued in December 2003 and entitled, <br />Estimated Areas Exceeding Containment System Remediation Goals for Water Year 2002. <br />The SEO should have a copy (used to prevent issuance of well permits in contaminated <br />areas). <br />• They have no concern about reversing or affecting the groundwater gradient by pit pumping. <br />They are close to the S. Platte and there is a very strong ground water gradient to the NW, <br />towards the S. Platte. <br />• Larger pits north of the site and much closer to the plume have been dewatering with no <br />discernible effect on the DIMP plume, indicating that the plume is relatively stable. <br />• DIMP does not adsorb to soil easily; but it is extremely soluble. <br />• Sec. 16 is about 1%: miles NW of the RMA boundary and historical sampling shows DIMP is <br />not in the area at any level of concern. The last remnants are'/, mile away. <br />• They commonly sample from domestic and other private wells, so Mr. LaRock agrees with <br />Mr. Naugle that the 150 GPM Flow rate should not affect the outcome of the analysis for the <br />semi-volatile DIMP. <br />• In conclusion, he would not be concerned about DIMP at these properties. <br />Sampling by the Contractor for the Operator <br />I left a phone message on Friday, October O8, 2004, for Mark Molen, with Molen & Associates, <br />LLC [(303)450-1600], who performed the sampling, requesting a copy of his field notebook <br />documenting the well water was "stable," as defined by CDPHE ground water sampling protocol, <br />prior to collecting the DIMP sample. <br />Mark Molen returned my call on Thursday, October 14, 2004, with a message saying that he was <br />waiting on the OK from his client to provide us a copy of his field notebook regarding these <br />samples. <br />A meeting has been set with him and Mike Refer of Aggregate Industries for Tuesday, October <br />25, 2004. <br />In a telephone conversation with Mark Molen on Thursday, October 21, 2004, he indicated that <br />arranging access to the site was difficult, so he attempted to make it as easy on the well owner as <br />possible and do everything in one trip. As such, he obtained the flow rate information (150 GPM) <br />from a neighbor who apparently has an agreement with the well owner to use this well for <br />irrigation (or farms the owner's land). Anecdotally, Mr. Molen reported that with the well <br />operating, the stream of water discharged from the 2-%' pump discharge pipe had such force that <br />he could not hold the 5-gallon bucket in front of it, but had to catch the sample as the pump shut <br />down. This is not really indicative because at 45 gpm, this flow would fill the bucket in less than 7 <br />seconds. <br />Perhaps we/he should invite that District's Water Commissioner (or Asst.) to join him next time to <br />assess whether the well is not exceeding its permitted flow rate and has not changed its place of <br />use. <br />2 <br />