The United States Geological Survey (USGS) has conducted two hydrologic investigations related to the uranium enrichment facility near Piketon, in the Scioto River Valley in south-central Ohio. The Scioto is a tributary of the Ohio River, flowing into the Ohio at Portsmouth, upstream from Cincinnati.

The site and vicinity are underlain by an incised bedrock valley filled with about 70-85 feet of sand and gravel outwash, deposited by meltwater streams at the edge of an active glacier. The glacial outwash sediments are covered by a thin veneer of alluvium deposited during more recent flooding of the Scioto River and Big Beaver Creek.

The sand and gravel outwash in the Scioto River Valley is one of Ohio’s principal aquifers. Because of its high yields, it is widely used as a source of public and private water supply. One of the DOE wells at the southwest corner of the Piketon site yields as much as 1300 gallons per minute. The water table typically is about 15 feet below land surface, with fluctuations as great as 12 feet annually.

Piketon is about 20 miles beyond the southern limit of glaciation in a rugged, hilly terrain. The Scioto River winds through this scenic, sparsely settled region in a wide, flat-bottomed, and steep-sided valley, 400-500 feet below the general level of the higher adjacent hills. At Piketon the valley is about 1 1/2 miles wide.

The Scioto River valley predates the modern river, having been established by streams of former drainage systems which cut through 35 to 55 feet of shale to create a deep, narrow valley with steep walls. As the glaciers melted, outwash filled the valley with 100 feet or more of sand, gravel, and silt. The modern Scioto River has since removed 20 to 30 feet of the outwash deposits. The remnant terraces on the sides of the valley mark the original level of the glacial deposits. The village of Piketon is built above the present flood plain on one of these sand and gravel terraces.

At the site, groundwater in the outwash deposits, received as surface runoff from the thinly covered bedrock uplands, as deep percolation from direct precipitation, and as recharge from Big Beaver Creek, flows beneath the terraces and discharges to the Scioto River. The average velocity of horizontal groundwater flow is on the order of 1 to 2.5 feet per day. The southwest corner of the Piketon site is only 2000 feet from the Scioto River. Under ordinary conditions, groundwater could travel this distance in as little as 2 to 5 years.

However, groundwater and surface water at the site are highly interconnected. High-stage events on the Scioto River cause frequent flow reversals in the outwash aquifer that allow streamwater to travel as much as 190 feet inland. Bank-storage events occur frequently. In 1991, approximately 19 flow reversals occurred. One flow-reversal event in July and August 1992 lasted 17 days. Once every one to two years, on the average, the Scioto River overflows its banks and inundates the flood plain. A severe flood in March 1963 produced a peak discharge of 47 million gallons per minute.

There is also a groundwater aquifer in the bedrock underlying the glacial outwash. Generally, water flows upward from the underlying bedrock to the outwash aquifer. However, during periods of bank-storage in the outwash aquifer, vertical flow between the two formations is reversed, and groundwater flows from the outwash into the bedrock aquifer.

It would appear that the Piketon site is a risky, even reckless, location for nuclear reprocessing and incineration facilities, or for relocation of spent nuclear fuel, even on a “temporary” basis. Containment would have to be fail-safe and fool-proof. Failure of containment would jeopardize both the scenic Scioto River and a vital groundwater aquifer. Because the two are highly interconnected, contamination of one would inevitably contaminate the other.

DIRECT TESTIMONY ON THE PROPOSED GNEP SITE AT, PIKETON, OHIO
March 8, 2007

From 1963 to 1965, and again in 1991 and 1992, the United States Geological Survey (USGS) conducted hydrologic investigations related to the Portsmouth facility, one of three gaseous diffusion plants in the United States which enrich uranium with the uranium-235 isotope. The facility is located at a site near Piketon, in the Scioto River Valley in south-central Ohio. The Scioto River is a first-order tributary of the Ohio River, flowing into the Ohio at Portsmouth, upstream from Cincinnati.

The site and vicinity are underlain by an incised bedrock valley filled with about 70-85 feet of sand and gravel outwash, deposited by meltwater streams at the edge of an active glacier. The glacial outwash sediments are composed predominantly of dolomite, quartz, and calcite, and are covered by a veneer of modern alluvium deposited during more recent flooding of the Scioto River and Big Beaver Creek. The alluvium is composed of clay and silty clay, interbedded with sand and gravelly sand. The alluvium is generally 5-10 feet thick, although greater thicknesses are found near the Scioto River, in old meander scars, and near Big Beaver Creek.

The sand and gravel outwash in the Scioto River Valley is one of Ohio’s principal aquifers. Because of its high yields, it is widely used as a source of public and private water supply. One of the DOE wells at the southwest corner of the Piketon site yields as much as 1300 gallons per minute. Sand and gravel deposits similar to those in the Scioto River valley occur in nearly all the major valleys in Ohio as well as in major valleys throughout the glaciated region. Approximately three-fourths of the groundwater used in Ohio is pumped from such aquifers.

Piketon is about 20 miles beyond the southern limit of glaciation in a rugged, hilly terrain. The area is underlain by a thick sequence of sedimentary rocks, consisting predominantly of shale interbedded with sandstone. The Scioto River winds through this scenic, sparsely settled region in a wide, flat-bottomed, and steep-sided valley, 400-500 feet below the general level of the higher adjacent hills. At Piketon the valley is about 1½ miles wide.

The Scioto River valley predates the modern river, having been established by streams of former drainage systems. Prior to glaciation, the ancestral Portsmouth River flowed northward along a path roughly parallel to, and 2 miles east of, the present-day Scioto River, but at an elevation approximately 150 feet higher than the present-day river valley. The Portsmouth River was a short tributary that emptied into the ancestral Teays River at a point 5 miles north of Piketon, near Waverly. When the Teays River drainage system was disrupted by the Kansan glacial advance, the direction of flow was reversed, and the former Portsmouth river valley became part of the southward-flowing ancestral Newark River. It generally followed the course of the older stream, but near Piketon it cut a new channel farther to the west.

Regional uplift occurred after the Newark River was established, causing the rejuvenated stream to downcut its channel into a deep, narrow valley with steep walls. The Newark River cut through 35 to 55 feet of shale to an elevation of approximately 465 feet above sea level. The ancestral Newark River flowed near the west valley wall, as does the present-day Scioto River. The valley floor was broad and relatively flat, with very steep sides, especially along the west valley wall.

The second (Illinoian) and third (Wisconsinan) glacial advances both halted about 20 miles north of Piketon. As the glaciers melted, outwash filled the Newark River Valley with 100 feet or more of sand, gravel, and silt. The modern Scioto River, which came into existence during the final retreat of the Wisconsinan glacier, has since removed 20 to 30 feet of the outwash deposits. The remnant terraces on the sides of the valley mark the original level of the glacial deposits. The village of Piketon is built above the present flood plain on one of these sand and gravel terraces.

Today the glacial outwash deposits are a groundwater aquifer. At the site, the aquifer flows in a west-southwestward direction, perpendicular to the terrace ridge. The water table typically is about 15 feet below land surface. The altitude of the water table fluctuates approximately 4 feet annually beneath the eastern half of the valley; but closer to the Scioto River, the water table fluctuations are greater, as much as 12 feet annually.

A groundwater budget, or water balance analysis, for the site and vicinity indicates that the outwash aquifer received 17.7 inches of recharge during 1992. Of this amount, 72% came from infiltrating precipitation, and 28% came from the surface waters of Big Beaver Creek.

Most outwash aquifers are anisotropic, which means that their permeability is not the same in all directions. The permeability of an outwash aquifer, measured vertically, or transverse to the bedding, is typically much lower than the permeability measured horizontally, or parallel to the bedding. Relatively low vertical permeability of a sand and gravel aquifer commonly results from the presence of interbedded layers of fine-grained sediment such as silt or clay, which retard downward percolation. (Scientists classify soil particles according to size, the finest particles being clay, and successively larger particles being silt, sand, and gravel. In general, the smaller the particle size, the lower the permeability). In the field test, the flow of water through the outwash aquifer was largely horizontal, that is, parallel to the bedding.

The ability of an aquifer to transmit water is defined by its transmissivity (measured in ft2/day), which is equal to the thickness of the aquifer (in feet) multiplied by its hydraulic conductivity (in ft/day). The outwash aquifer is 70-85 feet thick. Its horizontal hydraulic conductivity, based on results of multiple-well aquifer tests, ranges from 400 to 560 feet per day.

Groundwater flows through an aquifer in relation to its hydraulic conductivity and its hydraulic gradient. The level to which water rises in a cased well is the hydraulic head. When a number of cased wells tap the same aquifer, the drop in hydraulic head between two wells divided by the horizontal distance between them is the hydraulic gradient. In most cases, groundwater velocity is proportional to the hydraulic gradient. However, where an aquifer is anisotropic, the flow direction will reflect a balance between the path of least resistance (maximum hydraulic conductivity) and the steepest hydraulic gradient.

At the site, groundwater in the outwash deposits, received both as surface runoff from the thinly covered bedrock uplands and as deep percolation from direct precipitation, moves under low gradients to discharge into the Scioto River. Natural groundwater gradients are estimated to range between 5 and 10 feet per mile. The average velocity of groundwater flow is on the order of 1 to 2 feet per day (Norris and Fidler, 1969), or 1.5 to 2.5 feet per day (Jagucki et al., 1995). The southwest corner of the Piketon site is only 2000 feet from the Scioto River. Under ordinary conditions, groundwater could travel this distance in as little as 2 to 5 years.

However, groundwater and surface water at the site are highly interconnected. Water levels in test wells clearly illustrate that Big Beaver Creek recharges the outwash aquifer east of the site. From this area, groundwater flows beneath the terraces at the site and discharges to the Scioto River west of the site. All of the near-river hydrographs are characterized by rapid fluctuations in response to changing river stage (water levels in the river), an indication that the riverbed is relatively permeable and the outwash aquifer and the river are in close hydraulic connection.

High-stage events on the Scioto River cause frequent flow reversals in the outwash aquifer that allow streamwater to travel a maximum observed distance of 190 feet inland, as indicated by multiple-well aquifer test data. A zone of oxidizing waters is found in shallow groundwater for several hundred feet adjacent to Big Beaver Creek and the Scioto River. This zone of oxidizing groundwater is caused by the periodic inflow of surface waters to the aquifer.

Bank-storage events occur frequently, as evidenced by records from electronic data loggers at the site. In 1991, approximately 19 flow reversals occurred. The maximum duration of a flow-reversal event during the study period was 17 days in July and August 1992.

Once every one to two years, on the average, the Scioto River overflows its banks and inundates the flood plain. A severe flood in March 1963 produced a peak discharge of 105,000 cubic feet per second (47 million gallons per minute).

There is also a groundwater aquifer in the bedrock underlying the glacial outwash. Generally, the hydraulic heads in the bedrock aquifer are higher than in the outwash aquifer, in which case, consistent upward leakage from the underlying bedrock to the outwash deposits occurs. However, during periods of bank-storage in the outwash aquifer, vertical flow between the two formations is reversed, and groundwater flows from the outwash into the bedrock aquifer.

It would appear that the Piketon site is a risky, even reckless, location for nuclear reprocessing and incineration facilities, or for relocation of spent nuclear fuel, even on a “temporary” basis. Containment would have to be fail-safe and fool-proof. Failure of containment would jeopardize both the scenic Scioto River and a vital groundwater aquifer. Because the two are highly interconnected, contamination of one would inevitably contaminate the other.

REFERENCES

Robert L. Bates and Julia L. Jackson, Editors, 1984, “Dictionary of Geological Terms,” Third Edition, Anchor Press/Doubleday, Garden City, New York.

Martha L. Jagucki, Christopher D. Finton, Abraham E. Springer, and E. Scott Blair, 1995, “Hydrogeology and Water Quality at the Management Systems Evaluation Area near Piketon, Ohio,” United States Geological Survey Water-Resources Investigations Report 95-4139.

Stanley E. Norris and Richard E. Fidler, 1969 “Hydrogeology of the Scioto River Valley Near Piketon, South-Central Ohio,” United States Geological Survey Water-Supply Paper 1872.

Richard H. Phillips and David T. Snow, 1998, “A Conceptual Model for Contaminant Transport in Karst Aquifers at the WIPP Site,” Submitted to the United States Environmental Protection Agency.

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Richard Hayes Phillips holds a Ph.D. in Geomorphology from the University of Oregon, 1987. His dissertation is entitled: “The Prospects for Regional Groundwater Contamination due to Karst Landforms in Mescalero Caliche at the WIPP Site near Carlsbad, New Mexico.” He has written or co-authored more than twenty professional papers on proposed or existing nuclear sites in New Mexico, Oklahoma, and Texas, and has been recognized as an expert witness in Resource Conservation and Recovery Act (RCRA) proceedings. He has taught courses in geology, geography and history at seven colleges and universities.