William R. Meyer | Geology Reports

USGS1979

Effects of seepage from fly-ash settling ponds and construction dewatering on ground-water levels in the Cowles unit, Indiana Dunes National Lakeshore, Indiana

Part of the Indiana Dunes National Lakeshore shares a common boundary with the Northern Indiana Public Service Company (NIPSCO). This area is underlain by unconsolidated deposits approximately 180 feet thick. NIPSCO accumulates fly ash from the burning of coal in electric-power generating units in settling ponds. Seepage from the ponds has raised ground-water levels above natural levels approximately 15 feet under the ponds and more than 10 feet within the Lakeshore. NIPSCO is presently (1977) constructing a nuclear powerplant, and construction activities include pumping ground water to dewater the construction site. The company has installed a slurry wall around the site to prevent lowering of ground-water levels within the Lakeshore. Plans call for continuous pumping through at least December 1979. A multilayered digital flow model was constructed to simulate the ground-water system. The model was used to demonstrate the effects of seepage from the fly-ash ponds on ground-water levels. Also, the model indicated a decline of 3 feet or less in the upper sand unit and 5 feet or less in the lower sand unit within the Lakeshore.

Indiana↗

USGS1979

Geohydrologic setting of and seepage from a water-supply canal, Indianapolis, Marion County, Indiana

The Indianapolis Water Company Canal is underlain by alluvial and outwash deposits. The water level in the canal on July 21, 1978, was above the water table along the entire reach of the canal upstream from the Fall Creek aqueduct, and, therefore, water was seeping downward from the canal into these deposits along this entire reach. Because of the highly variable lithology of the deposits underlying the canal, the seepage rate was probably also highly variable. Discharge measurements were made at selected points along the canal, and differences between successive measurements were calculated to determine the rate of water loss. The differences were smaller than the potential error in any of the measurements, however, and thus do not directly substantiate that water is being lost. The rate of water loss over the Fall Creek aqueduct by the skimming process could be as high as 43 cubic feet per second, assuming a 5% potential error for discharge measurements made at both ends of the aqueduct. Lower stages and water temperatures would decrease the rate of water loss. Observed ground-water levels were above the canal bottom at three locations along the canal. Lowering these levels below the bottom would increase seepage by approximately 9 cubic feet per second.

Indiana↗

USGS1975

Availability of ground water in Marion County, Indiana

County constitute the most extensive aquifers in the county. Four areally distinct sand and gravel aquifers were mapped in the drift during the course of this study. The aquifer of greatest economic importance consists of sand and gravel deposits of glacial-outwash origin which coincide with the courses of the White River and Fall Creek. Ground water in this aquifer is generally unconfined. Three thin, areally discontinuous, sheetlike deposits of sand and gravel situated one above the other occur in the till-plain area of the county. These deposits coalesce in some areas, but generally are separated by beds of silt and clay of varying thickness which cause the ground water in the till-plain aquifers to be semiconfined. The uppermost 100 feet (30 metres) or so of limestone and (or) dolomite underlying the glacial drift constitutes an aquifer of secondary importance in the county. This aquifer is separated from the unconsolidated aquifers either by silt and clay or by shale. The present movement of ground water through these aquifers is generally toward the White River, Fall Creek, Eagle Creek or Buck Creek. Based on seepage data, water levels in the aquifers in April and May 1974, and subsequent electric-analog-model analysis, discharge of ground water by seepage into the streams in the glacial outwash averages about 42 cubic feet per day per foot (3.9 cubic metres per day per metre) of channel length. A four-layer electric-analog model incorporating the geometry and hydraulic characteristics of the aquifers, the confining beds and the stream- aquifer connection was constructed to determine the feasibility and hydrologic results of proposed plans for future ground-water development. Three large well fields were simulated in the model of the glacial-outwash aquifer, with pumping nodes situated so as to take advantage both of high transmissivity areas in the aquifer, and of recharge from the streams. A series of model experiments were carried out to test the capacity of the aquifers to sustain increases in pumpage. In all of these, a new equilibrium was established within 6 years of simulated pumpage. In two of these experiments, water levels in the discharging wells were allowed to draw down to approximately half of the saturated thickness of the glacial-outwash aquifer. At this drawdown limit, the total discharge of wells in the system was found to be 59 million gallons per day (2.6 cubic second) assuming that the streams were fully connected to the upper third of the glacial-outwash aquifer. In two other experiments, discharging wells were allowed to drawdown an average of two-thirds of the saturated thickness of the glacial-outwash aquifer. At this limit, the total discharge was found to be 72 million gallons per day (3.2 cubic metres per second) using the conservative stream-aquifer connection, and 103 million gallons per day (4.5 cubic metres per second) assuming a full connection. Some dewatering of the aquifer was associated with the 72 million gallons per day (3.2 cubic metres per second) discharge. In all experiments, the amount that could be pumped from the confined aquifers without disturbing existing domestic wells was found to be small.

Indiana↗