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P. C. Mills

Publications and source records attributed to P. C. Mills.

14 recordsLinked to original sources
USGS2015

Wolfcampian brachiopods from the Bird Spring Group, Wamp Spring area, Las Vegas Range, Clark County, Nevada

The Wamp Spring section of the Bird Spring Group consists of approximately 1,600 feet of carbonate rocks subdivided into a basal platy limestone member, lower cliff-forming member, and upper cliff-forming member. Triticites, Schwagerina , and Schubertella kingi in the platy limestone member indicate an early Wolfcampian age. Schwagerina, Schubertella kingi , and a distinctive assemblage of brachiopods, similar to the West Texas fauna, including Kozlowskia kingi, Elliottella aff. E. multicostata, Leurosina sinesulca, Gypospirifer cf. G. infraplicus , and Composita cf. C. apheles , indicate that the upper cliff-forming member is late Wolfcampian. The lower cliff-forming member is tentatively assigned to the middle Wolfcampian. The Wamp Spring sequence correlates temporally with the BSe “formation” of the Bird Spring Group. In addition to the previously mentioned taxa, the fossil-rich upper cliff-forming limestone member includes the new species Pontisia boodi, Crurithyris wampensis , and Calliprotonia (?) n. sp. A, as well as Hustedia culcitula, Crenispirifer (?) sp., Cenorhynchia (?) sp., Kutorginella (?) sp., marginiferids, lyssacine hexactinellid sponges, pleurotomarid and bellerophontid gastropods, cidaroid echinoids, rugose corals, cylindrical cryptostome bryozoans, and nuculids.

Journal of Paleontology↗
USGS2007

Water balance at a low-level radioactive-waste disposal site

The water balance at a low-level radioactive-waste disposal site in northwestern Illinois was studied from July 1982 through June 1984. Continuous data collection allowed estimates to be made for each component of the water-balance equation independent of other components. The average annual precipitation was 948 millimeters. Average annual evapotranspiration was estimated at 637 millimeters, runoff was 160 millimeters, change in water storage in a waste-trench cover was 24 millimeters, and deep percolation was 208 millimeters. The magnitude of the difference between precipitation and all other components (81 millimeters per year) indicates that, in a similar environment, the water-budget method would be useful in estimating evapotranspiration, but questionable for estimation of other components. Precipitation depth and temporal distribution had a very strong effect on all other components of the water-balance equation. Due to the variability of precipitation from year to year, it appears that two years of data are inadequate for characterization of the long-term average water balance at the site.

Water Resources Bulletin↗
USGS2005

Herbicides and degradates in shallow aquifers of Illinois: Spatial and temporal trends

During the fall of 2000, the occurrence was examined of 16 herbicides and 13 herbicide degradates in samples from 55 wells in shallow aquifers underlying grain producing regions of Illinois. Herbicide compounds with concentrations above 0.05 μg/L were detected in 56 percent of the samples. No concentrations exceeded regulatory drinking water standards. The six most frequently detected compounds were degradates. Water age was an important factor in determining vulnerability of ground water to transport of herbicide compounds. Unconsolidated aquifers, which were indicated to generally contain younger ground water than bedrock aquifers, had a higher occurrence of herbicides (73 percent of samples) than bedrock aquifers (22 percent). Temporal analysis to determine if changes in concentrations of selected herbicides and degradates could be observed over a near decadal period indicated a decrease in detection frequency (25 to 18 percent) between samplings in 1991 and 2000. Over this period, significant differences in concentrations were observed for atrazine (decrease) and total acetochlor (increase). The increase in acetochlor compound concentrations corresponds to an increase in acetochlor use during the study period, while the decrease in atrazine concentrations corresponds to relatively consistent use of atrazine. Changes in frequency of herbicide detection and concentration do not appear related to changes in land use near sampled wells.

Illinois↗
USGS2003

Hydrogeologic and ground-water-quality data for Belvidere, Illinois, and vicinity, 2001–02

This report presents miscellaneous geologic, hydrologic, and ground-water-quality data collected in and near Belvidere, Ill. during May 2001–November 2002. The data were collected for two studies conducted by the U.S. Geological Survey during 1990–2002, but subsequent to publication of the final interpretive reports for the studies. The cooperative studies with the U.S. Environmental Protection Agency and Illinois Environmental Protection Agency evaluated the hydrogeology, ground-water-flow system, and distribution of contaminants in the glacial drift and bedrock (primarily Galena-Platteville) aquifers underlying the vicinity of Belvidere, including the Parson's Casket Hardware Superfund site. Data presented in the report include lithologic descriptions, geophysical logs, water levels, hydraulic characteristics, field-measured characteristics of water quality, and laboratory analyses of volatile organic compounds, major ions, trace elements, nutrients, and herbicides.

Illinios↗
USGS2000

Geology, hydrology, and ground-water quality of the upper part of the Galena-Platteville aquifer at the Parson's Casket Hardware Superfund site in Belvidere, Illinois

The geology, hydrology, hydraulic properties, and distribution of contaminants in the upper part of the Galena-Platteville aquifer at the Parson's Casket Hardware Superfund site in Belvidere, Illinois, were characterized on the basis of data collected from boreholes by use of packer assemblies, flowmeter logging, and borehole ground-penetrating radar. Four permeable intervals were identified in the upper part of the Galena-Platteville aquifer: (1) a shallow, subhorizontal fracture from 37 to 40 feet below land surface; (2) an inclined fracture from 75 to 85 feet; (3) a shallow, vuggy interval from 90 to 100 feet; and (4) a deep, vuggy interval from about 140 to 180 feet. The calculated horizontal hydraulic conductivity of the two fractured intervals exceeds 50 feet per day and is more than an order of magnitude greater than that of the vuggy intervals. Water levels in the Galena-Platteville aquifer respond to pumping cycles in the Belvidere municipal-supply wells below a depth of at least 180 feet. Results of flowmeter logging and constant discharge aquifer testing indicate that the shallow, subhorizontal fracture is hydraulically connected to the overlying unconsolidated aquifer. Discrete inclined fractures are the primary conduits for vertical ground-water flow between the permeable units within the upper part of the Galena-Platteville aquifer, and perhaps for flow to the deeper parts of the aquifer. The inclined fractures may become less permeable with depth. A maximum effective porosity in the deep, vuggy interval of 8.8 percent was calculated from hydrologic and borehole radar-tomography data collected during tracer testing. The average maximum horizontal ground-water velocity through this interval was calculated at 21.4 feet per day using cross-hole radar tomography under a hydraulic gradient of 1.25 feet per foot. Trichloroethene, trichloroethane, and tetrachloroethene are the primary volatile organic compounds detected in the aquifer. There is no distinct pattern of the concentration of volatile organic compounds with depth; however, the highest concentrations tend to be present in the shallow part of the aquifer at the site. Movement of organic compounds through vertical fractures may account for their presence in the deeper parts of the aquifer.

Illinois↗
USGS1998

Geologic, hydrologic, and water-quality data from selected boreholes and wells in and near Belvidere, Illinois, 1989-96

This report presents selected geologic, hydrologic, and water-quality data collected in and near Belvidere, Ill., during 1989-96. The data were collected primarily by the U.S. Geological Survey and U.S. Environmental Protection Agency in support of an ongoing ground-water study of the glacial drift aquifer and bedrock aquifers of Ordovician and Cambrian age underlying the area. These data were collected from 8 boreholes and 52 wells within a 4 square-mile urbanized part of the 80 square-mile study area. Data include stratigraphic, lithologic, and physical descriptions of rock cores from 5 boreholes; geophysical logs of 23 boreholes; surface-geophysical surveys at 3 sites; ground-water levels at 46 wells; horizontal hydraulic conductivity estimated from slug tests at 32 boreholes and wells; and ground-water-quality information at 26 boreholes and wells. Ground-water-quality information include field characteristics and laboratory analyses of inorganic constituents, tritium, volatile organic compounds, and semivolatile organic compounds. Also included are construction logs for 11 monitoring wells and descriptions of the methods used for data collection.

Illinois↗
USGS1997

Rock-stratigraphic nomenclature, lithology, and subcrop area of the Galena-Platteville bedrock unit in Illinois and Wisconsin

The Galena-Platteville bedrock unit is a dependable source of ground water for many private well owners and some municipal-water-supply systems in northern Illinois (Hackett, 1960) and in Wisconsin. The carbonate lithology of the unit contributes to the availability of ground water and also to the susceptibility of the unit to ground-water contamination. Susceptibility to contamination is greatest in areas where the unit is overlain by only a thin layer (less than 50 feet) of soil or unconsolidated glacial deposits. Within the study area in Illinois and Wisconsin (fig. 1), volatile organic compounds and other contaminants have been detected in groundwater samples from various sites (Kay and others, 1989; Mills, 1993a, 1993b; Kay and others, 1994). Known and suspected sources of contaminants are numerous, including landfills and industrial facilities. To determine the possible effects of contamination on the ground-water supply, an understanding of the regional hydrogeologic framework of the Galena-Platteville bedrock unit is needed. Published map and point data describing the geologic and hydrologic properties of the Galena-Platteville bedrock unit are available from many sources. The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, Region 5, has selected and compiled pertinent data. The objective of this study is to publish these data in a series of concise map reports and a bibliographic report listing available sources of information by county for the Galena-Platteville bedrock unit. Investigators involved in site-specific studies within the subcrop area will be able to utilize these reports to design effective site investigations. This report presents the rock-stratigraphic nomenclature of the lithologic units that make up the Galena-Platteville bedrock unit (fig.2) and provides a brief, generalized description of the lithologic characteristics of each unit. Sources with more detailed descriptions of lithology can be found below in SELECTED REFERENCES. Figure 3 is a map, created from published maps of various scales, showing the areal extent of the Galena-Platteville subcrop and major known geologic structural features in Illinois and Wisconsin. The subcrop area of the Galena-Platteville bedrock unit is that area where the unit crops out, or is the uppermost bedrock unit and is overlain by soil or glacial deposits. The unit is present at depth under younger bedrock units south and east of the subcrop area and is absent north and west of the subcrop area. Data sources used to prepare the map are included in SELECTED REFERENCES.

Illinois, Wisconsin↗
USGS1993

Vertical distribution of hydraulic characteristics and water quality in three boreholes in the Galena-Platteville Aquifer at the Parson's Casket Hardware Superfund site, Belvidere, Illinois, 1990

The U.S. Geological Survey investigated contaminant migration in the Galena-Platteville aquifer at the Parson's Casket Hardware site in Belvidere, Ill. This report presents the results of the first phase of the investigation, from August through December 1990. A packer assembly was used to isolate various depth intervals in three 150-foot-deep boreholes in the dolomite aquifer. Aquifer-test data include vertical distributions of vertical hydraulic gradient, horizontal hydraulic conductivity (K), and response of water levels in observation wells to borehole pumping. Water-quality data include vertical distributions of field-measured properties and laboratory determinations of concentrations of volatile organic compounds (VOC's). vertical hydraulic gradients in the aquifer were downward. The downward gradients ranged from less than 0.01 to 0.37 foot/foot. The largest gradient was associated with an elevated-K interval at 115 to 125 feet below land surface. The hydraulic characteristics of strata within the aquifer seem to be generally consistent across the site. The strata can be subdivided into five hydraulic units with the following approximate depth ranges-and K's : (1) a 1- to 5-foot-thick weathered surface at about 35 feet below land surface, 1-200 ft/d (feet per day); (2) 35-80 feet, 0.05-0.5 ft/d; (3) 80-115 feet, 0.5 ft/d; (4) 115-125 feet, 0.5-10 ft/d; and (5) 125-150 feet, 0.5 ft/d. Water-level drawdowns were detected in one shallow bedrock observation well during pumping of some of the packed intervals in a nearby borehole, indicating that the degree of vertical connection between some intervals in the aquifer may be greater than that between others. During development pumping of one borehole, drawdowns were detected in a nearby well screened in the lower part of the overlying glacial-drift deposits, indicating hydraulic connection between the glacial drift aquifer and the bedrock aquifer. VOC's were detected throughout the upper half (about 150 feet ) of the bedrock aquifer beneath the site. The detected compounds were predominantly chlorinated ethenes and ethanes (maximum concentration was 570 ppb (parts per billion) of trichloroethylene. There was a positive correlation between concentrations of VOC's, specific conductance, and K. The distribution of VOC concentrations indicate that the low-K dolomite beds in the Galena-Platteville aquifer may impede the downward migration of the VOC's and that the high-K beds and fissures may provide pathways for the lateral migration of VOC's through the aquifer. Contaminant migration is possibly affected by ground-water flow through vertical fractures that connect shallow beds with deeper beds in the aquifer, thus explaining the detections of some VOC species at intermittent depths.

Open-File Report↗
USGS1993

Hydrogeology and water quality of the Galena-Platteville aquifer at the Parson's Casket Hardware Superfund site, Belvidere, Illinois, 1991

The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, investigated the hydrogeology of the Galena-Platteville aquifer and its relation to contaminant migration at the Parson's Casket Hardware Superfund site in Belvidere, Ill. This report presents the results of the second phase of the investigation, which lasted from March through October 1991. The uppermost bedrock units beneath the study site are the Galena and Platteville Groups1; these bedrock units immediately underlie a glacial drift aquifer. The Galena and Platteville Groups, which consist predominantly of dolomite, compose the Galena-Platteville aquifer, and extend from about 40 to 320 feet below land surface. The unconfined Galena-Platteville aquifer is partitioned into five hydrogeologic units. The uppermost unit, the weathered surface of the bedrock, has a horizontal hydraulic conductivity that ranges from about 1 to 200 feet per day. The four underlying units have hydraulic conductivities that range from about 0.01 to 1 foot per day. Vertical hydraulic gradients in the aquifer are typically downward. Horizontal groundwater flow generally is southward to southeastward from the site toward the Kishwaukee River. Three notable bedding-plane solution fissures and three fractures that crosscut the bedding planes are identified within the dolomite bedrock. The inclined fractures are assumed to function as conduits that connect high conductivity horizontal fissures, thus allowing more rapid vertical movement of ground water and contaminants than would be expected in the generally low conductivity dolomite matrix. A multiple-well, constant-discharge aquifer test confirms the heterogeneity and anisotropy of the dolomite aquifer. The hydraulic characteristics of the uppermost part of the bedrock aquifer are somewhat different than the characteristics of the deeper part(s) of the aquifer. This is because the principal conduits for water movement are in the deeper part(s) of the aquifer. Ground-water flow in the Galena-Platteville aquifer beneath the study site is affected by pumping of Belvidere Municipal Wells No. 4 and No. 6. Water levels in wells screened near the vertical midpoint of the aquifer are affected by the municipal-well pumping substantially more than are water levels in wells screened near the top of the aquifer.

Open-File Report↗
USGS1993

Hydrogeology and water quality of the Galena-Platteville aquifer at the Parson's Casket Hardware Superfund site, Belvidere, Illinois, 1991-92

The purpose of this letter is to describe the results of the final phase (phase 3) of the U.S. Geological Survey's (USGS) ground-water investigation at the Parson's Casket Hardware site, Belvidere, Ill. (figs. 1 and 2), for the U.S. Environmental Protection Agency (USEPA). Included in this letter are brief descriptions of (1) study methods employed in the phase 3 investigation that have not been previously described in earlier reports, and (2) results of the phase 3 investigation as they relate to the results of the previous phases of the investigation. The data from the phase 3 investigation that are presented and described herein were collected during November 1991-January 1992. The Galena-Platteville aquifer is the uppermost bedrock aquifer beneath the site. The Glenwood Formation of Ordovician age, a potential confining unit, separates the Galena-Platteville aquifer from the underlying St. Peter Sandstone aquifer (fig. 3). The St. Peter Sandstone aquifer is an important source of ground water to Belvidere and other cities in the region. The phase 3 investigation was done (1) to determine the lithology of the Glenwood Formation; (2) to determine the vertical distribution of horizontal hydraulic conductivity (K) and concentrations of volatile organic compounds (VOC's) in the upper 150 ft (feet) of the Galena-Platteville aquifer at an existing monitoring location, borehole G127GP (figs. 2 and 3) ; and (3) to confirm the presence or absence of VOC's in the St. Peter Sandstone aquifer at a new monitoring location, well G127SP (figs. 2 and 3). Additional components of the site investigation described in this letter include determination of vertical hydraulic gradients between the Galena-Platteville and St. Peter Sandstone aquifers and in situ measurement of selected water-quality characteristics (pH, temperature, specific conductance, Eh, and dissolved oxygen) in borehole G127GP. The results of the first and second phases of the USGS investigation at the Parson's Casket Hardware site are presented in two previous USGS Open-File Reports prepared for the USEPA (Mills, 1993a, 1993b) . These reports describe the hydrogeology of the study site, principally the Galena-Platteville aquifer, and the distribution of VOC concentrations in the Galena-Platteville aquifer. (The stratigraphic nomenclature used in this report is that of the Illinois State Geological Survey (Willman and others, 1975, p. 47-87) and does not necessarily follow the usage of the USGS. The aquifer nomenclature is that generally used by the Illinois State Geological Survey and the U.S. Environmental Protection Agency.) The previous two reports also describe most of the study methods employed in the phase 3 investigation.

Open-File Report↗
USGS1992

Effects of low-level radioactive-waste disposal on water chemistry in the unsaturated zone at a site near Sheffield, Illinois, 1982-84

A 1982-84 field study defined the chemistry of water collected from the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois. Chemical data were evaluated to determine the principal naturally occurring geochemical reactions in the unsaturated zone and to evaluate waste-induced effects on pore-water chemistry. Samples of precipitation, unsaturated-zone pore water, and saturated-zone water were analyzed for specific conductance, pH, alkalinity, major cations and anions, dissolved organic carbon, gross alpha and beta radiation, and tritium. Little change in concentration of most major constituents in the unsaturated-zone water was observed with respect to depth or distance from disposal trenches. Tritium and dissolved organic carbon concentrations were, however, dependent on proximity to trenches. The primary reactions, both on- site and off-site, were carbonate and clay dissolution, cation exchange, and the oxidation of pyrite. The major difference between on-site and off-site inorganic water chemistry resulted from the removal of the Roxana Silt and the Radnor Till Member of the Glasford Formation from on-site. Off-site, the Roxana Silt contributed substantial quantities of sodium to solution from montmorillonite dissolution and associated cation-exchange reactions. The Radnor Till Member provided exchange surfaces for magnesium. Precipitation at the site had an ionic composition of calcium zinc sulfate and an average pH of 4.6. Within 0.3 meter of the land surface, infiltrating rain water or snowmelt changed to an ionic canposition of calcium sulfate off-site and calcium bicarbonate on-site and had an average pH of 7.9; below that depth, pH averaged 7.5 and the ionic composition generally was calcium magnesium bicarbonate. Alkalinity and specific conductance differed primarily according to composition of geologic materials. Tritium concentrations ranged from 0.2 (detection limit) to 1,380 nanocuries per liter. The methods of constructing, installing, and sampling with lysimeters were evaluated to ensure data reliability. These evaluations indicate that, with respect to most constituents, the samples retrieved from the lysimeters accurately represented pore-water chemistry.

Open-File Report↗
USGS1992

Effects of low-level radioactive-waste disposal on water chemistry in the unsaturated zone at a site near Sheffield, Illinois, 1982-84

A 1982-84 field study defined the chemistry of water collected from the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Ill. Chemical data were evaluated to determine the principal, naturally occurring geochemical reactions in the unsaturated zone and to evaluate waste-induced effects on pore-water chemistry. Samples of precipitation, unsaturated-zone pore water, and saturated-zone water were analyzed for specific conductance, pH, alkalinity, major cations and anions, dissolved organic carbon, gross alpha and beta radiation, and tritium. Little change in concentration of most major constituents in the unsaturated-zone water was observed with respect to depth or distance from disposal trenches. Tritium and dissolved organic carbon concentrations were, however, dependent on proximity to trenches. The primary reactions, both on-site and off-site, were carbonate and clay dissolution, cation exchange, and the oxidation of pyrite. The major difference between on-site and off-site inorganic water chemistry resulted from the removal of the Roxana Silt and the Radnor Till Member of the Glasford Formation from on-site. Off-site, the Roxana Silt contributed substantial quantities of sodium to solution from montmorillonite dissolution and associated cation-exchange reactions. The Radnor Till Member provided exchange surfaces for magnesium. Precipitation at the site had an ionic composition of calcium zinc sulfate and an average pH of 4.6. Within 0.3 meter of the land surface, infiltrating rainwater or snowmelt changed to an ionic composition of calcium sulfate off-site and calcium bicarbonate on-site and had an average pH of 7.9; below that depth, pH averaged 7.5 and the ionic composition generally was calcium magnesium bicarbonate. Alkalinity and specific conductance differed primarily according to composition of geologic materials. Tritium concentrations ranged from 0.2 (detection limit) to 1,380 nanocuries per liter. The methods of constructing, installing, and sampling with lysimeters were evaluated to ensure data reliability. These evaluations indicate that, with respect to most constituents, the samples retrieved from the lysimeters accurately represented pore-water chemistry.

Illinois↗