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..,. = ~ III IIIIIIIIIIIII III^ i ~ ~ ~ 999 - . FOX 8~ ASSOCIATES OF COLORADO, INC. CONSULTING ENGINEERS AND GEOLOGISTS DENVER OFFICE 47651NDEPENDENCE STREET WREAT RIDGE, COLORADO 60033 (303)424-5578 Mount Carbon Metropolitan District P.O. Box 27923 Denver, Colorado 80227 Attention: Martha Taylor June 20, 1984 Job No. 1-1107-6292-00 Subject: Subsidence Potential for a Proposed Roadway Alignment Over Under- mined Areas, Sections 24 and 25, Township 4 South, Range 70 West, Jefferson County, Colorado References: 1) Mine Maps on File with the State of Colorado, Division of Mines for the Rooney-White Ash, Satanic, Sharon, and Bluebird Nos. 1 and 2 Mines 2) Geologic Map of the Morrison Quadrangle, Jefferson County, Colorado by G. R. Scott, 1912, U.S.G.S. Map I-790-A 3) Subsidence Hazard Map, Morrison Quadrangle, Prepared for the Jefferson County Planning Department by Amuedo and Ivey, 1978, Map No. 7657-D-5 Dear Ms. Taylor: At your request, we have reviewed literature and performed field work with regard to past mining activities north and south of Alameda Parkway in the Laramie Formation. This investigation was undertaken to preliminarily eval- uate subsidence potential in the area to allow conceptual feasibility plans for development of the vacant land in the area. Of particular concern to the tlient is thle hazard potential for the routing of McIntyre Street as it has been preliminarily planned to pass over undermined areas. Between 1910 and 1936, five underground coal mines operated in Sections 24 and 25, Township 4 South, Range 70 West. The mines all extracted sub-bitu- minous coal from the lower Laramie Formation. The Laramie coals strike approximately north 24 degrees west and in outcrop dip to the east at from 60 degrees to near vertical. Coal mine maps indicate that the dip flattens considerably with depth. The Rooney-White Ash Mine was operated from 1910 to 1915 and was iocated north and south of the present alignment of Alameda Parkway. Records indicate that more than 3,800 tons of coal were mined from a seven foot thick seam during those years. To the south along strike of the coal, a series of coincidental mines were operated until 1936 adjacent to the White Ash Mine, beginning with the Satanic Mine between 1918 and 1922 which mined an eight to 15 foot thick seam of coal on two levels up to 200 feet deep, extracting more than 44,000 tons. That mine was continued as the.Sharon Mine between 1923 and 1929 with a reported extraction of just under 10,000 tons. The seam was last mined in the area as the Bluebird Nos. 1 and 2 until 1936. The maps of the Bluebird Mines were last dated in 1934, with the A FO% COMPANY