2010-07-07_INSPECTION - C1981008 (2)

Home Browse Search

STATE OF COLORADO DIVISION OF RECLAMATION, MINING AND SAFETY Department of Natural Resources 1313 Sherman St., Room 215 Denver, Colorado 80203 Phone: (303) 866-3567 FAX: (303) 832-8106 DRMS INTERNAL MEMORANDUM DATE: JULY 7, 2010 TO: MARCIA TALVITIE FROM: DAN MATHEWS ' RE: NEW HORIZON SOIL SAMPLES PERMIT C-1981-008 COLORADO D I V I S I O N OF RECLAMATION MINING SAFETY Bill Ritter, Jr. Covemor James S. Martin Executive Director Loretta E. Pineda Director As you may recall, during my inspection at New Horizon Mine on June 4, 2010, 1 took six soil samples from subsoil and Bench 1 overburden horizons, in various locations where the material had been exposed by stripping operations. I delivered the samples to Grand Junction Labs on June 7, and received analyses for the samples on June 17, 2010. Due to cost considerations (GI Labs does not accept credit cards), analyses were limited to pH, conductivity, and estimated texture (as opposed to the more costly texture by particle size analysis). All of the pH and conductivity levels were in the acceptable range; the prime farmland lift B soil sample and one of the upper Bench 1 overburden samples had an estimated texture of Loamy Sand, which is listed in the permit Table 2.05.4(2)(d)-1 as "unacceptable". These were in essence "grab" samples, as I did not attempt to sample through the entire thickness of the Lift B soil horizons or the upper Bench 1 overburden on the prime farmland. Given the thick lifts that are removed for both the Lift B soil and the Bench 1 overburden, it is likely that mixing of the loamy sand material with finer textured materials higher in the profile (with respect to Lift B soils), or lower in the profile (with respect to Bench 1 overburden) would result in the acceptable sandy loam to sandy clay loam textures typically reported. It should also be kept in mind that the textures reported here are based on estimates, and not on particle size analysis. The operator should, however, exercise care in salvage operations to ensure that the material replaced as Lift B Topsoil on the Morgan West prime farmland, or as Bench 1 subsoil substitute on the Morgan East prime farmland, does meet the soil texture suitability criteria. Note also, that Sample #4 from the thinly bedded, weathered sandstone/shale strata near the base of the Bench 1 zone contained a high percentage of pebble size rock fragments. It is likely that this lower zone is the source of a significant component of the gravel that is reported in the Bench 1 surface spoils following replacement. Another source of rock fragments of various sizes would be the sandstone lenses that occur higher in the Bench 1 overburden zone, occasionally quite near the soil surface. Operator needs Office of Office of Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines