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April 9, 2004 <br />would be discorrtinued for that season. If after zero head is realized, monitoring would only continue in <br />a particulaz season in the case that unusual weather conditions are conducive to significant amounts of <br />precipitation and subsequent infiltration to the mine workings. On the basis of historical data, such a <br />condition would be very rare. Discharge has not been observed from the mine during the typical <br />"monsoon" or high precipitation season in late July and August. Furthermore, the NPDES (CDPS) <br />permit (Permit No. 600000, Facility No. COG-600452) exempts monitoring during the months of <br />December through March due to winter inaccessibility to the site. <br />Mine Scepage Monitoring <br />Demonstrating that there is no near term shortcirouiting from the mine pool to the surface in the forth <br />of seeps or springs is an issue that will require study and further discussion. The physical <br />characteristics of the area adjacent to and downgradient of the Research Mine are important to mention <br />here. The gulches that are at the head of Logan Wash and immediately adjacent to or down gradient <br />from the Research Mine are considered ephemeral. These gulches, in fact, have not flowed during <br />work visits conducted by W WL and others at the mine during at least the last 10 years. Lower Logan <br />Wash, approximately 5 miles downgredient from the mine, has been observed flowing after intense <br />thunderstorms. in addition, a spring located adjacent to the Research Mine originates several hundred <br />feet above the portal, and its flow infiltrates the access road bench and has never been observed flowing <br />across the road. During past periods of peak mine discharge, the discharge water flowed across the <br />mine access road, into a steel gathering pipe, and then infiltrated into the fill and gulch colluvium <br />within a short (10 ft) distance downgradient <br />W WL and past operators at the Logan Wash Mine and Research Mine, have not identified any seeps or <br />springs downgradient of the Research Mine within the mine permit area; a thorough reconnaissance has <br />not been conducted. At this time, it is not possible to conclude that water within the Research Mine is <br />hydraulically wnnected to downgradient seeps, if they exist, or that seep water would have received <br />groundwater with or without the mine's influence. Should a seep be discovered, it is possible that the <br />seep has received groundwater from the Research Mine workings, or naturally from the general area for <br />many years. The conditions of the CDPS discharge permit do not disallow discharge from the mine <br />through natural flow (i.e. porous or fracture flow). Furthermore, water has historically discharged from <br />the mine and allowed by CDPS permit to flow into the adjacent dry gulch. Within the past 5 years, <br />only one parameter, oil and grease, exceeded its permitted concentration during two sampling events in <br />July 2000, and April 2001. However, immediate follow-up sampling showed low and no detection of <br />oil and grease in the mine water. It is possible that the initial detection of oil and grease was due to field <br />or laboratory error, including contamination from the discharge pipe itself. <br />W WL is in the process of sampling springs in the mine and surrounding area as part of a study aimed at <br />the possibility of inactivating the CPDS permit. To address the possibility of new seeoaee from the <br />sealed mine, W WL will conduct a seep and spring reconnaissance of the area adjacent to and <br />downgradient of the Research Mine portal prior to potential head build-up in the spring of 2004. <br />Identified seeps will be marked in the field for future monitoring. Monitoring of identified seeps and <br />springs and reconnaissance for new seeps will continue on a monthly basis during the period from <br />April to December or until head has subsided to zero R. Photographs will be taken of the mine portal <br />area during each visit. Should any new seeps (areas where evidence of previous seepage is lacking) be <br />identified, W WL will consider alternatives for assessing the potential hydraulic connection between the <br />mine pool and identified seeps. <br />W WL will implement the above monitoring plan for mine pool head and surface seepage once <br />approved by DMG. As indicated in TR No. 4, GSHI may decide to initiate other water management <br />ahematives for mine pool water within the Research Mine. W WL will inform DMG of any changes in <br />