2014-09-30_PERMIT FILE - M1983067

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Epvi0roi)Mei)t, lC. LARRY E. O'BRIAN 7985 VANCE DRIVE, SUITE 205A FOUNDER ARVADA, COLORADO 80003 STEVAN L. O'BRIAN 303 - 423 -7297 PRESIDENT FAX 303 - 423 -7599 September 25, 2014 Mr. Tyler O'Donnell Division of Reclamation, Mining & Safety 1313 Sherman St, Suite 215 Denver, CO 80203 Dear Tyler; ®jV' RE: Albert Frei & Sons, Inc. DIVI SEP 3 0 2014 Stagecoach Pit - Update AQN�N 6R S�ATIp M.L.R.B. Permit # M- 1983 -067 AND SAFE N On behalf of my client Albert Frei & Sons, Inc. I am submit- ting this correspondence to update and keep you appraised of what Albert Frei & Sons, Inc., is doing to investigate and mitigation the ground water issues to the east of the Stagecoach Pit. In the last update (9/5/14) I laid out a plan to begin investigating the Zigan Lake overflow drain pipe and to make changes to the outlet in an attempt to improve or increase the flow thru the pipe to lower the lake level. In the past this was an accepted method for regulating the groundwater elevation between the lake and the Stagecoach slurry wall and it worked for nearly 4 years. On Friday, September 12, 2014 a "T" was installed on the discharge end of the pipe. An extension was added to divert the flow from the catch basin so that the catch basin was taken out of the line in hopes of improving flow thru the system. A meter was installed in the discharge pipe so Frei could monitor the amount of water leaving the Zigan Lake. Once the water began to flow thru the pipe, the meter registered a flow of between 490 and 520 feet per minute. Attached are pictures taken on 9/16/14 showing the newly installed "T ", diversion pipe and the meter. Note that the catch basin was partially drained. At this level there is no longer discharge from the basin and we believe that it will eventually dry up. The photo taken 9/18/2014, shows the water over the inlet grate after 6 days the ones taken on 9/25/14 shows, Ben Frei standing on the grate in one inch or less of water. We estimate the lake level had dropped by 8 to 10 inches based on photos in the inspection report and that approximately 7,414,600 gallons ( =22.75 ac -ft) had been discharged from the lake during the 13 days.