2008-04-25_REVISION - M1988112 - Laserfiche WebLink

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Preliminary Adequacy -ssues 2 April 25, 2008 AM-03, M-1988-112 Through AM-03, the Applicant proposes to discontinue the water treatment program and route the West Pit water to the Salazar Ranch where it will be released, untreated, as irrigation water. The irrigation activity proposed at the Salazar Ranch is located in an aquifer recharge area and in close proximity and up-gradient to the water supply for the Town of San Luis. As noted by the objecting parties, many of whom are residents of San Luis, the proposed cessation of water treatment and release of the untreated water on the Salazar Ranch appears to increase, rather than minimize, the potential for disturbance to the hydrologic balance. Pursuant to Rule 3.1.6, please demonstrate how the proposed irrigation activity at Salazar Ranch will minimize disturbances to the prevailing hydrologic balance as opposed to continuation of the water treatment program. Pursuant to Rule 6.4.20(1)(e), please clarify how the proposed plan will provide for net improvements in the protection of human health, property or the environment. As noted in the attached memo from DRMS staff member David Bird, the alluvial aquifer underlying the Salazar Ranch has been classified by the Colorado Water Quality Control Commission (WQCC). Therefore, the Salazar Ranch is a specified area and pursuant to Rules 3.1.6(1)(b) and 3.1.7(1)(b), the water quality standards listed on Tables 1 through 4 of The Basic Standards For Ground Water, 5 CCR 1002-41 (Regulation 41), shall apply. As such, the permit condition values proposed on Table G.4-3 of AM-03 for iron at 0.3 mg/L, manganese at 0.05 mg/L, sulfate at 250 mg/L, and pH at 6.5 to 8.5, are appropriate. However, the values proposed for fluoride at 4 mg/L and Total Dissolved Solids (TDS) at 500 mg/L exceed the standards of Regulation 41 and must be revised to 2 mg/L for fluoride and 400 mg/L for TDS. As discussed below, the Division recommends expansion of the list of parameters for analysis to include the full suite of water quality standards listed in Tables 1 through 4 of Regulation 41. The irrigation activity proposed at the Salazar Ranch appears to have potential to release unauthorized pollutants to the ground water. According to section G.3 of AM-03, the untreated West Pit water exceeds the water quality standards for fluoride and manganese. As noted in the attached staff memo, the untreated West Pit water also exceeds the standard for TDS, and application of the untreated water to the soils of Salazar Ranch has potential to leach arsenic to the ground water. AM-03 attempts to address the fluoride and manganese but does not appear to address the arsenic and TDS. Please address the issues identified in the attached staff memos from David Bird and Allen Sorenson. Pursuant to Rule 3.1.5(11), AM-03 must demonstrate that no unauthorized release of pollutants to ground water will occur from any materials mined, handled or disposed of within the permit boundary. Therefore, an adverse impact on ground water quality may reasonably be expected and pursuant to Rule 3.1.7(7)(a), the Division requires a ground water monitoring plan sufficient to verify compliance with Rules 3.1.6(1)(b) and 3.1.7(1)(b). Under section G.4.2.1, the Applicant proposes to verify compliance for the 281-acre irrigation area with only one monitoring well, SLM-2. SLM-2 is located on the south permit boundary approximately 3,500 feet and down- gradientfrom the application site, and approximately 2,000 feet and up-gradient from the Town of San Luis water supply wells. SLM-2 is located at the most distant down-gradient opportunity for a point of compliance, and as such, appears to benefit from the maximum opportunity for attenuation and dilution. of contaminants. However, being proximal to the permit boundary, SLM-2, as the solitary monitoring well for the irrigation activity, inappropriately minimizes opportunities for remediation necessary to prevent off-site damage.