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<br />Review of CC&V Response to Commitment No. 36 <br />Memo to B. Keffelew, June 27, 1994 <br />Page 2 <br /> <br />Arequa Gulch downstream of the proposed facility will be regulated of course as surface water <br />and will be subject to compliance with surface water regulations already established by WQCD. <br />Surface and or groundwater that flow through the underdrain and then recharge groundwater will <br />be subject to regulation under the groundwater program. <br />For groundwater, the list of regulated elements and compounds depends on the groundwater use, <br />whereas the list for surface water consists of that established by CDH for the Arequa Gulch <br />discharge permits. Because it is the charge of the Division of Minerals and Geology to regulate <br />the sources of potential contaminants, it follows that the Division must assure that the <br />appropralte materials have been collected and that the applicable elements and compounds have <br />been analyzed. <br />For purposes of this review, the Division assumes that the surface meteoric water which will <br />flow through the underdrains, and the groundwater which will exit into Arequa Gulch and flow <br />through the underdrains, ultimately will rechazge both to groundwater through fractures and to <br />surface water. Therefore, the Division concludes that all surface water and groundwater <br />parameters, elements and compounds that are regulated should be measured in water dischazging <br />from the underdrains in Arequa Gulch. The Division assumes that rock to be placed in the <br />underdralns have a furite solubility, and that solutions discharging from the underdrains will be <br />changed as a result of interactions with the underdrain material. The Division further concludes <br />that these parameters, elements and compounds must be measured using techniques capable of <br />detecting those components either at or below the levels to which they may be regulated. These <br />assumptions and conclusions are acknowledged in some form in the permit commitments. <br />DATA REVIEW <br />A. Acid -Base Potential <br />Results of acid base accounting are adequate to demonstrate that weathering of the Arequa Gulch <br />Underdrain by local ephemeral flushing of rainwater will not present an acid problem for either <br />surface water or groundwater. Provided the tested materials are representative of those that <br />willb a used in the underdrain, no further acid-base testing will be necessary. <br />B. Metals Leaching Potential (Meteoric Water Mobility Procedure) <br />CC&V analyzed the 10 samples for 20 metals, alkalinity, pH, nitrate, TDS, chloride, fluoride <br />sulfate, total cyanide and WAD cyanide following leaching under the Meteoric Water Mobility <br />