2002-11-01_REVISION - M1977424 - Laserfiche WebLink

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Early mining and MIS operations were conducted at the Research Mine (the southeast portion of the Logan Wash Mine workings) where shale oil was first recovered from MIS Retort ] E in 1973. Occidental developed and produced shale oil from a total of eight retorts using the underground MIS process. Oil shale was produced from Retorts lE, 2E, and 3E in the Research Mine. These small retorts produced a combined 4,200 barrels of shale oil. Retort 3E, the largest of the experimental Research Mine retorts, was 32 feet (ft) long by 32 ft wide by 113 ft high. Commercial-size retorts 4, 5, 6, 7, and 8 were constructed in the main Logan Wash Mine, located immediately (2000 ft) north of the Research Mine portal. These retorts varied in size from 120 ft long by 120 ft wide by 257 ft high (Retort 4) to 165 ft long by 165 ft wide by 245 ft high (Retorts 7 and 8). The combined production from Retorts 7 and 8 was approximately 200,000 barrels of shale oil. The last commercial-sized retort (Retort 8) was shut down in February 1983. Between 1983 and 1991, portions of the mine's infrastructure (piping, instrumentation, and other equipment) was dismantled and transported offsite for reuse. The mine has been inoperable since the winter of 1991, when OOSI ceased oil shale exploration activities. GSHI, on behalf of OOS[, has overseen management at the Logan Wash Mine since 1996. Occidental began collecting water quality data from the wells, springs, and retorts as early as 1976. The monitoring program was modified through the years to meet State permit requirements. In 1983, as many as 9 alluvial wells, 12 deep (bedrock) wells, two retort 7 wells, two retort 8 wells and two springs were being sampled on a monthly or quarterly basis. Between April 1997 and November 1999, OOSI monitored five surface water sites as required by CDPHE to support a proposed combined discharge of mine water and retort water from the evaporation pond. These sites included: P-1 (the upper manhole above the lined evaporation pond); POND-1 (the lined evaporation pond), lIN-1, (near the mouth of an unnamed drainage at Road 204, and downstream from Logan WashBoan Creek confluence); RC-1 (Roan Creek above confluence with Logan Wash and below Conn Creek); and RC-2 (Roan Creek near its confluence with the Colorado River). Sampling of these sites was discontinued because it was found that the combined waters would not meet water quality discharge requirements. In 1982, Occidental began monitoring water quality under the NPDES program. In September of 1986, Occidental formally acquired NPDES permit CO-0029947 and has since monitored two NPDES discharge sites near the mine, outfall 00t located in the Logan Wash drainage below the main mine waste-rock pile and outfall 002 located at the Research Mine portal. The NPDES outfall sites discharge non-retort mine water.