Site selection and characterization of the Sand Point landfill site, Eddy County, New Mexico

—Two landfills in southern Eddy County have been closed and the remaining landfill is expected to be closed by about mid-I994. Several sites and locations for a new landfill near Carlsbad have been examined and the Sand Point site (NW 1 / 4 sec. I 1, T2 IS, R28E) east of Carlsbad was selected for characterization. Four deeper drill holes were converted to hydrological observation wells after obtaining geological samples. Ground water depths range from about 168 ft to 222 ft below the surface. Five shallower boreholes (140 to 150 ft) were drilled to verify the geology of the interior of the site and that ground water would be more than 100 ft below the base of a landfill. Surface features show minor drainage along the southeastern corner of the site. The Mescalero caliche underlies soil from the Serino series and elongate fields of coppice dunes. The Plio(?)-Pleistocene Gatuňa Formation is nearly 300 ft thick in drill holes at the site and is underlain by the Permian Dewey Lake Formation. The Dewey Lake may be somewhat thicker under the site because of subsidence before Gatuňa erosion. The Dewey Lake– Gatuňa relationships may indicate erosion and valley fill. Sand Point meets siting criteria in New Mexico Environment Department regulations. Some additional hydrological work is expected at the site and a permit will be sought during 1993.