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Suite 200. 760 So. Cobrado Blvtl. P. 0. for 17583, Terminal Annex Denver, Cobrado 80217 Tekphone 303.753-1W00 III IIIIIIIIIIIII III RECEIVED DFC 22 1980 MINED LAND RECLAMATION=COAL' COLO. DEPj, OF NATURAL RESOURCES December 18, 1980 Jim Herron Reclamation Specialist Mined Land Reclamation 423 Centennial Boulevard 1313 Sherman Street Denver, Colorado 80203 Dear Jim: Northern Coal Company Herein is a report of the groundwater monitoring related to construction of the coal refuse facility near P1eeker. Construction began on November 3, 1980 and was completed on December 5, 1980. Included is a list of all piezometers within the area, with groundwater measurements taken before, during and after the construction process. Weather during the construction was generally mild; November 13 was the only day in which precipitation was experienced in the form of light rain mixed with snow. During construction, a number of wells were necessarily removed, and these are shown on the revised map Figure 13.2.2-B. Also shown is the location of the newly installed piezometer, RD-16, as requested during our meeting of October 2, 1980. The trench drain between piezometers P-2 and P-3 was constructed according to the permit plans on December 1 through December 3. Maximum depth was 16 feet and no trace of water was encountered anywhere in the excavation. In view of this, piezometers RD-16 and P-3 showed relatively no change in groundwater level. Because no water was encountered in the trench drain on the refuse side of the road, there was no need to install the tentative drains on the south side. During construction, water was encountered in only two locations: 1) a soggy area in the watershed diversion ditch near the lower stock pond. 2) a wet area along the inside toe of the road from station 2+50 to 4+30. To insure road stability, an additional trench drain was installed along this area as shown on revised map 13.2.2-B. Average depth of the drain was 3 feet and it produced water at a rate of about 5 gallons per minute.