2005-02-02_REVISION - M1999034 - Laserfiche WebLink

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Mrs. and Mr. Topper M-1999-034 February 2, 2005 Page 2 Division -Rocky Mountain Arsenal team, as well as Tri-County Health Department, indicate that DIMP is highly soluble, and therefore not sinking or floating (neither a DNAPL nor an LNAPL), especially at current RMA concentrations. The same contacts report that DIMP is not likely to volatilize, as it is semi-volatile, and that it is fairly common to sample from irrigation (150 GPM) wells without concerns for volatilization. In the February 1, 2005, letter to Aggregate Industries, the Division clarified the Board Order's requirement for a Monitoring Plan and elements that the Monitoring Plan must and should include. When these items are addressed, it will simultaneously address any remaining monitoring plan components noted in your October 22, 2003 letter. The February 1, 2005, letter to Aggregate Industries also distinguishes the need to purge casing volumes not borehole volumes and provides related calculation corrections. As we have discussed, the pre-mining sample of the well will need to be repeated since the purge time was inadequate. Use of a temporary inline flow meter for two well sampling events would be acceptable, but will not be required by the Division. Since well and pump data is often lacking on wells sampled by TCHD, their procedure is to purge wells for 45 minutes prior to sampling. In this case, well construction and pump installation reports for this well from the Division of Water Resources have been used. Granted, unless the pump has been replaced, it is 36 years old so its pumping capacity may have diminished. However, at the time the pump was tested it delivered a constant yield of 70 GPM, but was and is limited by the permit to 45 GPM. Unless you indicate otherwise, the Division will assume that a 45 GPM flow rate is a low estimate, and suitable for well purge volume calculations. In your December 7, 2004 a-mail, you expressed concern over "purging five boring volumes" due to the waste of water and the electrical cost. Using this conservative estimate, the minimum purge time is 12 minutes, much less than the 45 minutes called for in TCHD's procedures. In your a-mail, you proposed that the Division review the sampling protocol per the U. S. EPA Region Vlll Minimum Requirements for Field Sampling Activities. This e-mail has been forwarded to Aggregate Industries, and they may propose to implement its provisions. As stated in the Division's February 1, 2005 letter, "CDPHE's 'Ground-Water Permit Guidance Suggested Monitoring Well Sampling Protocol' and Tri-County's extensive DIMP experience at the Rocky Mountain Arsenal and targeted procedures more specifically and comprehensively address this particular analyte than any others the Division has encountered. Therefore, their procedures are considered competent for our purposes, as well. Lake sample collection per the Texas Commission on Environmental Quality's (TCEQ, f/k/a TNRCC) 'Surface Water Quality Monitoring Procedures' is acceptable." The CDPHE guidance is available online at htto://www.cdohe.state.co.usJwa/PermitsUnit/GW Well Mon Guide.PDF The Board Order does not require sampling separate surface water bodies. The Findings of Fact in the State Engineer's Hearing Order Case No. 03-SE-08 stated that Well No. 32883 "cannot legally operate unless it is included in acourt-approved plan for augmentation....and therefore, the well cannot legally operate at this time." Pursuant to a conversation between Mr. Topper and me in November 2004, Mr. Topper was going to obtain a letter from the State Engineer's Office ("SEO") authorizing pumping the well for sampling purposes. I advised providing the request, in writing, to Jeff Deatherage of the SEO. The Division has still not seen the request or the SEO letter. I have since spoken with the SEO, and as long as the pumped water is not put to beneficial use, the well can be pumped solely for water quality monitoring purposes.