Geology topics

Research about Globe, Arizona

Source-linked reports with geographic coverage including Globe, Arizona.

3 recordsLinked to original sources

USGS2002

Characterization of hydraulic conductivity of the alluvium and basin fill, Pinal Creek Basin near Globe, Arizona

Acidic waters containing elevated concentrations of dissolved metals have contaminated the regional aquifer in the Pinal Creek Basin, which is in Gila County, Arizona, about 100 kilometers east of Phoenix. The aquifer is made up of two geologic units: unconsolidated stream alluvium and consolidated basin fill. To better understand how contaminants are transported through these units, a better understanding of the distribution of hydraulic conductivity and processes that affect it within the aquifer is needed. Slug tests were done in September 1997 and October 1998 on 9 wells finished in the basin fill and 14 wells finished in the stream alluvium. Data from the tests were analyzed by using either the Bouwer and Rice (1976) method, or by using an extension to the method developed by Springer and Gellhar (1991). Both methods are applicable for unconfined aquifers and partially penetrating wells. The results of the analyses show wide variability within and between the two geologic units. Hydraulic conductivity estimates ranged from 0.5 to 250 meters per day for the basin fill and from 3 to 200 meters per day for the stream alluvium. Results of the slug tests also show a correlation coefficient of 0.83 between the hydraulic conductivity and the pH of the ground water. The areas of highest hydraulic conductivity coincide with the areas of lowest pH, and the areas of lowest hydraulic conductivity coincide with the areas of highest pH, suggesting that the acidic water is increasing the hydraulic conductivity of the aquifer by dissolution of carbonate minerals.

Arizona↗

USGS1996

Hydrology and geochemistry of aquifer and stream contamination related to acidic water in Pinal Creek basin near Globe, Arizona

Hydrologic and geochemical research has identified and characterized the physical and chemical processes that control the evolution and movement of metal contaminants in ground water beneath Miami Wash and lower Pinal Creek. The dissolution of calcite in the alluvial aquifer has slowed and neutralized part of the acidic plume, and the sorption of some metals such as nickel and copper to other solids in the subsurface has lowered concentrations of these metals in the ground water.

Arizona↗

USGS1996

Colloidal-facilitated transport of inorganic contaminants in ground water: part 1, sampling considerations

Investigations at Pinal Creek, Arizona, evaluated routine sampling procedures for determination of aqueous inorganic geochemistry and assessment of contaminant transport by colloidal mobility. Sampling variables included pump type and flow rate, collection under air or nitrogen, and filter pore diameter. During well purging and sample collection, suspended particle size and number as well as dissolved oxygen, temperature, specific conductance, pH, and redox potential were monitored. Laboratory analyses of both unfiltered samples and the filtrates were performed by inductively coupled argon plasma, atomic absorption with graphite furnace, and ion chromatography. Scanning electron microscopy with Energy Dispersive X-ray was also used for analysis of filter particulates. Suspended particle counts consistently required approximately twice as long as the other field-monitored indicators to stabilize. High-flow-rate pumps entrained normally nonmobile particles. Difference in elemental concentrations using different filter-pore sizes were generally not large with only two wells having differences greater than 10 percent in most wells. Similar differences (>10%) were observed for some wells when samples were collected under nitrogen rather than in air. Fe 2+ /Fe 3+ ratios for air-collected samples were smaller than for samples collected under a nitrogen atmosphere, reflecting sampling-induced oxidation.

Arizona↗