Data from core analyses, aquifer testing, and geophysical logging of Denver Basin bedrock aquifers at Castle Pines, Colorado

Abstract

In 1987, the U.S. Geological Survey began an investigation to obtain detailed geologic and hydrologic data pertaining to the bedrock aquifers in the Denver basin and to evaluate techniques for estimating aquifer characteristics by use of core analyses, aquifer tests, and geophysical logs. This report contains data collected during this investigation at a test site at Castle Pines, Colorado. Data consist of lithologic descriptions of about 2,400 feet of drill core and laboratory determinations of mineralogy, grain size, bulk and grain density, porosity, specific yield, and specific retention for selected core samples. Water-level data, atmospheric-pressure measurements, aquifer-compression measurements, and borehole geophysical logs also are included.

Groundwater levels in the Denver Basin bedrock aquifers of Douglas County, Colorado, 2011-2013

“…Studies within Douglas County that contributed to understanding the hydrologic resources include Hillier and others (1978), who examined the hydrology and water quality of the Arapahoe aquifer in the Englewood-Castle Rock area, and the Castle Pines core hole that fully penetrated the Arapahoe aquifer (Raforth and Jehn, 1990;Robson and Banta, 1990;Robson and Banta, 1993;Robson, 1995). Moore and others (2007) examined groundwater use and population growth and summarized the problems associated with groundwater development in Douglas County.…”

Quality of groundwater in the Denver Basin aquifer system, Colorado, 2003-5

“…33) and in surface efflorescence deposits in the basin (Herring and Walton-Day, 2007). Lignite is present in the bedrock aquifers, including in extensive beds (Soister 1978a(Soister , 1978bRobson and Banta, 1993;Raynolds and others, 2001) (table 1). Silicate reactions such as the dissolution of albite and precipitation of kaolinite were considered on the basis of the lithology of the bedrock aquifers for a number of samples but did not result in models with notable differences in adjusted ages; as a result, the simpler models (not including albite and kaolinite reactions) are described in this report (table 11).…”

“…For some models, recrystallization of calcite (isotopic exchange) was included as a mechanism to increase the modeled δ 13 C value when realistic mass-balance reactions alone resulted in modeled δ 13 C values that were too low relative to measured values. Carbonate minerals are present in the bedrock aquifers (Robson and Banta, 1993;Raynolds and others, 2001), although based on bedrock aquifer mineralogy, calcite recrystallization is not likely to be a dominant geochemical process; as a result, the modeled proportions of isotopic exchange included were relatively minor (≤0.6 millimoles per kilogram) (table 11). Gypsum has been detected in the bedrock aquifers (Raynolds and others, 2001; Amber Brenzikofer, Colorado Mineral Society, written commun., 2013) ( fig.…”

A geoarchaeological interpretation of the Lamb Spring Site, Colorado

“…Results of atomic absorption spectroscopy performed on the light mineral (sand) fraction (Table I) indicate the bedrock is significantly arkosic, with a total of 43.7% feldspars. While this might appear to support the earlier Dawson Arkose identification of Scott, all geological formations in the Denver Basin are frequently characterized as arkosic (Robson and Banta, 1993).…”