1999-03-08_PERMIT FILE - M1999025

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Grand Junction Pipe Surficial Geology Investigation Proposed Soaring Eagfe Gravel Pit, Grand Junction, Colorado January 25, 1999 Page 3 thin bedded to laminated bedded carbonaceous shale, mudstone and sil[stone. 1 GROUND WATER ' The ground water elevations are believed to be within 5 feet of the ground surface and arc largely controlled by the elevation of the Colorado River. This ground water should be considcred a permanent future of the site. Dewatering of the open pit during Honing will be required. A deeper ground water is present in the underlying rock deposits. This lower ground water is within several confined aquifers. Some of these confined water are potable. Information available to Lincoln DzVore, the U S. Geological Survey Professional Paper ii 4~ I, Geology and Artesian Water Supply, Grand Junction area, Colorado, S.W. Lohman, 1965, provides a drillers log of several walls penetrating some of the confined ' aquifers. Making corrections for topography and the structural dip of the beds, a sa1N ground water in the Dakota Formation could be anticipated approximately )50 foet below the ground surface, a thin potable aquifer in the Somerville Formation approximately 700 fee[ below the growmd surface and potable water in the Entrada Sandstone approwmately 1000 feaK below the ground surface. As can be seen from these depths, the confined water strata would be found az significant depths and would be separated from the proposed mineral extraction. SURFACE WATER ' Surface water on this tract, resulting from storm runoff is expected to be quite small, providing flooding of the Colorado River does not occur. ' ECONOMIC GEOLOGIC DEPOSITS ' The ecaromic deposit of consequence on this site is the sand and gravel of the Ancient Colorado River Terrace. The perched ground water on this site, which may be encountcre~ lx;RVeen 3 to 5 feet below the present ground surface, contains solubk: sulfate salts and other minerals in suflicicnt quantity [hat the water is not considered potable. These waters may, in some instances be utilized for irrigation but, are normally considcred to have excessive rrunerals. The confined waters in the Dakota, Summerville and Entrada Formauons are generally considered of minor consequence in this area It is not believed this proposed gravel extraction operation would ' a@'ect, either positively or adversely, these deeper, confined ground waters. I Some petroleum and significant amounts of natural gas have been prospected for and extracted from the Dakota, Burro Canyon and Momson Formations. The established producing gas fields are located north and northwest of this tract. These established producing gas fields are located in the desert area north of the Government Highline Canal and within the Bookcliffs, approximately 12 miles north of [his site. To our ' knowledge, exploration for natural gas or petroleum has not been accomplished in this portion of the Grand LJ