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---- - - - - -- Forwarded message ---- - - - - -- <br />From: John Hamrick <John.Hamrick @cotterusa.com> <br />Date: Mon, Apr 1, 2013 at 8:50 AM <br />Subject: Cotter <br />To: "Kaldenbach - DNR, Tom" <tom.kaldenbach @state.co.us> <br />T�X 100 <br />Toni — the adequacy comments should go out today, and here is the answer to question 6. <br />6. Please add to Exhibit E the minimum criteria that must be met before the in -situ trial is terminated and full -scale in -situ <br />treatment begins. <br />In -situ treatment of the mine pool will occur in two stages, the first being the addition of a heavy organic carbon source <br />into the mine as part of the backfill slurry during initial dewatering, which is expected to take up to four months. During <br />this initial dewatering, mine pool conductivity, oxidation /reduction potential (ORP), pH, and temperature will be monitored <br />continuously. Additionally, the constituents in the chart below will be analyzed on a monthly basis to supplement Cotter's <br />current quarterly mine -pool analysis, which shall continue to be performed. If beneficial effects from the initial addition of <br />the heavy carbon source are confirmed, Cotter will proceed with full -scale in -situ treatment of the mine pool at a level at <br />least 150 feet below the Steve level. <br />TDS <br />U <br />SO4 <br />Mo <br />Ra 226 <br />As <br />Ba <br />Fe <br />Table 1. Constituents to be Analyzed Monthly <br />I will also call. <br />John Hamrick <br />Vice President, Mill Operations <br />719 - 275 -7413 x 202 office <br />303 - 332 -1504 cell <br />