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February 9, 2001 <br /> Page 4 of 4 Pages <br /> No impact to the surface water hydrologic balance of the Middle Thompson Creek drainage was <br /> anticipated(permit,page 4-114). Monitoring through 1985 did not establish depletion to the North <br /> Thompson Creek and Middle Thompson Creek, and monitoring was discontinued in 1986 (permit, <br /> page 5-115b). <br /> "Surface entries and other accesses to the underground workings are located so that no gravity <br /> discharge of water from the mines occurs." (permit, page 4-115). Seals were designed for lower <br /> elevations projected to be below stable water levels subsequent to mine filling (permit,page 4-66). <br /> Seeps were noted from the Mine 1 portals on April 28, 1988 (seeps were actually reported in 1985 <br /> by a Department of Health, Environment and Safety inspector in the vicinity of the air return). <br /> Grouting was determined not to be a viable alternative to seepage control (permit,page 4-66g). Flow <br /> from the#3 Mine was anticipated and is described on page 4-115b of the permit. At this time,gravity <br /> discharges are evident at the Mine 1 and Mine 3 portals. Portal discharges, from both the Mine 1 and <br /> Mine 3 are collected and treated. <br /> "Water discharged will comply with the applicable CDPS permit." (permit,page 4-126)The report <br /> validates this statement for 2000 discharges. <br /> A statement that discharges from outfall 001 may slightly impact the quality of water in north <br /> Thompson Creek, and a hypothetical case, is described on page 4-122 of the permit. An increase of <br /> less than 10% in conductivity is considered insignificant (a discharge of 52 gpm, conductivity of <br /> 2083, stream flow of 5 cfs). A statement on page 4-122 of the PAP, and page 5 of the report, is that <br /> the Department of Health can consider a loading of one ton of salt per day a no-salt discharge. An <br /> expected maximum flow rate of 100 gpm from the No. 1 mine, with a TDS concentration of 1500 <br /> mg/l would yield a salt concentration of 0.9 tons per day. The average flow for 2000 was 36.8 gpm <br /> which equates to a discharge of 0.29 tons of salt per day(page 5 of the report) <br /> CC: Permittee <br /> Dan Hernandez <br /> C:\WPDOCS\NorthThompson\ahrrvwOO.025.doc <br />