Effect of reduced industrial pumpage on the migration of dissolved nitrogen in an outwash aquifer at Olean, Cattaraugus County, New York

Abstract

Ground water beneath an industrial park at Clean, N.Y. , contains nitrogen compounds in concentrations that in 1979 ranged from 100 milligrams per liter (mg/L as N) to 1,840 mg/L as N. Continuous pumping from seven industrial production wells and a purge well at the site has created a cone of depression within which all nitrogen compounds are contained and are thus prevented from migrating to nearby private and municipal-supply wells. Water from three of the production wells and the purge well contains 98 percent of all nitrogen removed at the well field. This water is used by a fertilizer plant in the industrial park for cooling and is continuously discharged to Twomile Creek a small intermittent stream in West Olean. A quasi-three dimensional two-layer digital ground-water flow model was developed to evaluate the effects of industrial and municipal pumping on the migration of the nitrogen-bearing ground water in the shallow outwash aquifer. The aquifer system consists of extensive coarse sand and gravel outwash that lies mostly within the top 100 feet of unconsolidated deposits beneath the floors of major valleys. In some areas, fine-grained lacustrine or till deposits confine deeper outwash. Several hypothetical schemes to minimize pumping while containing the nitrogen-bearing water were simulated to predict changes in the rate and direction of movement of contaminated ground water. Simulation of a full shutdown of the industrial well field and the purge well indicated that ground water flowing laterally from the area of contamination would migrate south to southwestward for about 5 years before reaching the municipal well field along the Allegheny River. Nitrogen concentrations of ground water arriving at the municipal well field would probably be significantly lowered through dilution, mechanical dispersion, and adsorption. With only the purge well in operation, ground water along the southwestern edge of the containment area could probably escape but would require 8 to 9 years to migrate to the municipal well field. Relocating the current industrial discharge from Twomile Creek to Allegheny River would cause water levels near Twomile Creek to decline an additional 1 to 3 ft, but operation of the industrial-production wells and the purge well would keep the contaminated ground water within the cone of depression. The loss of infiltration from Twomile Creek would cause streamflow in the Allegheny River and Olean Creek to decline by an additional 0.45 and 0.05 cubic feet per second, respectively. INTRODUCTION The U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, has been investigating the effects of industrial and municipal development of a shallow glacial outwash aquifer at Olean, N.Y. , in southeastern Cattaraugus County (fig. 1). The focus of these studies has been an area at and near an industrial park in north Olean, where large amounts of nitrogen compounds, including ammonia and urea, are manufactured for use in fertilizer and animal feed. Since 1969, high concentrations of nitrogen, primarily ammonia and nitrate, have been detected in the shallow aquifer at the industrial park. Although no single predominant source has been identified, the high concentrations have been attributed to various spills and leaks of fertilizer, process compounds, and wastewater that have infiltrated the soil and the aquifer system in this area over the years (Randall, 1977). 78° 30'00 78°27'30 I 78°25'00 i___ 78° 22'30 'Cattaraugus Co.I I I 42° 05'' '~~^ CITY , MUNICIPAL ^,<^fAkl WELL FIELD OLEAN X N. ^ OIL COMPANY'S PRODUCTION WELL FERTILIZER COMPANY'S PURGE WELL ?~~} APPROXIMATE AREA WHERE NITROGEN CONCENTRATIONS Q *'' EXCEED 10 MILLIGRAMS PER LITER BOUNDARY OF MODELED AREA CITY OR CITY OR VILLAGE BOUNDARY 2000 4000 6000 FEET 50