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Research about Rocky Mountain Arsenal

Source-linked reports with geographic coverage including Rocky Mountain Arsenal.

5 recordsLinked to original sources
USGS2012

Reservoir analysis of the Denver earthquakes: A case of induced seismicity

Injection of fluid wastes into the fractured Precambrian crystalline bedrock beneath the Rocky Mountain Arsenal near Denver triggered earthquakes in the 1960's. An analysis, based on the assumption that fluid flow in the fractured reservoir can be approximated by flow in a porous medium, is presented. The configuration and hydrologic properties of the reservoir are determined from two lines of evidence: (1) locations of earthquake hypocenters determined by seismic arrays installed at the Arsenal and (2) observed long-term decline in fluid levels in the injection well. Together these two sets of data indicate that a long, narrow reservoir, aligned in the direction N 60°W, exists. The reservoir is 3.35 km in width, extends 30.5 km to the northwest and infinitely to the southeast, and spans a depth interval from 3.7 to 7.0 km below land surface. It has a transmissivity of 1.08×10-5 m2/s and a storage coefficient of 1.0×10-5. Computed pressure buildup along the length of the reservoir is compared with the spatial distribution of earthquake epicenters. The comparison shows that earthquakes are confined to that part of the reservoir where the pressure buildup exceeds 32 bars. This critical value is interpreted as the pressure buildup above which earthquakes occur. The migration of earthquake epicenters away from the injection well, a phenomenon noted by previous investigators, can be accounted for by the outward propagation of the critical pressure buildup. The analysis is extended to examining the effects of rapid flow in fractures opened by high injection pressure. The results show that the effect is confined to a small region within 1 km of the injection well. The existence of a critical pressure buildup above which earthquakes occur is completely consistent with the theory on the role of fluid pressure in fault movement as presented by Hubbert and Rubey.

Colorado↗
USGS1999

Health status and relative exposure of mule deer and white-tailed deer to soil contaminants at the rocky mountain arsenal

We evaluated the health of 18 radio-collared deer [13 mule deer ( Odocoileus hemionus ) and 5 white-tailed deer ( O. virginianus )] from the Rocky Mountain Arsenal, near Denver, Colorado, USA, a Superfund site contaminated with a variety of materials, including organochlorine pesticides, metals, and nerve gas production by-products. Radio-collared deer were tracked for 1 to 3 years (1989–1992) to identify relative exposure to contaminants based on telemetry locations plotted on grid maps depicting known soil contaminant concentrations. At the end of the study, all animals were in fair or good body condition at the time of necropsy. Mean ages of mule deer and white-tailed deer were 7.4 (range 4–12) and 10.6 years (range 5–17), respectively. At necropsy, tissues were collected from the deer for serology, histopathology, and analysis for eight chlorinated hydrocarbons and two metals. Detectable residues of mercury were found in the kidneys of 10 deer (range 0.055–0.096 μg/g), dieldrin was found in fat ( n = 9) (range 0.02–0.72 μg/g), liver ( n = 4) (range 0.017–0.12 μg/g), and brain ( n = 1, 0.018 μg/g), and DDE was found in the muscle of one animal (0.02 μg/g). Relative exposure estimates derived from telemetry and soil contamination data were correlated with tissue levels of dieldrin ( p < 0.001) and mercury ( p = 0.05). Two mule deer had severe testicular atrophy, and one of these animals also had antler deformities. The prevalence of antibodies against epizootic hemorrhagic disease serotype 2 was 85%.

Colorado↗
USGS1985

Hydraulic gradient control for groundwater contaminant removal

The Rocky Mountain Arsenal near Denver, Colorado, U.S.A., is used as a realistic setting for a hypothetical test of a procedure that plans the hydraulic stabilization and removal of a groundwater contaminant plume. A two-stage planning procedure successfully selects the best wells and their optimal pumping/recharge schedules to contain the plume while a well or system of wells within the plume removes the contaminated water. In stage I, a combined groundwater flow and solute transport model is used to simulate contaminant removal under an assumed velocity field. The result is the approximated plume boundary location as a function of time. In stage II, a linear program, which includes a groundwater flow model as part of the set of constraints, determines the optimal well selection and their optimal pumping/recharge schedules by minimizing total pumping and recharge. The simulation—management model eliminates wells far from the plume perimeter and activates wells near the perimeter as the plume decreases in size. This successfully stablizes the hydraulic gradient during aquifer cleanup.

Colorado↗
USGS1977

Modeling chloride movement in the alluvial aquifer at the Rocky Mountain Arsenal, Colorado

A solute-transport model that can be used to predict the movement of dissolved chemicals in flowing ground water was applied to a problem of ground-water contamination at the Rocky Mountain Arsenal, near Denver, Colo. The model couples a finite-difference solution to the ground-water flow equation with the method-of-characteristics solution to the solute-transport equation. From 1943 to 1956 liquid industrial wastes containing high chloride concentrations were disposed into unlined ponds at the Arsenal. Wastes seeped out of the unlined disposal ponds and spread for many square miles in the underlying shallow alluvial aquifer. Since 1956 disposal has been into an asphalt-lined reservoir, which contributed to a decline in ground-water contamination by 1972. The simulation model quantitatively integrated the effects of the major factors that controlled changes in chloride concentrations and accurately reproduced the 30-year history of chloride ground-water contamination. Analysis of the simulation results indicates that the geologic framework of the area markedly restricted the transport and dispersion of dissolved chemicals in the alluvium. Dilution, from irrigation recharge and seepage from unlined canals, was an important factor in reducing the level of chloride concentrations downgradient from the Arsenal. Similarly, recharge of uncontaminated water from the unlined ponds since 1956 has helped to dilute and flush the contaminated ground water.

Colorado↗