U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting, Colorado Springs, Colorado, September 20-24, 1993, Water-Resources Investigations Report 94-4015

Use of Flowpath Simulation to Determine Contributing Areas and Traveltimes of Nonpoint-Source Ground-Water Contamination, Gloucester County, New Jersey

Abstract

The area of direct surficial recharge, potentially affected by nonpoint-source contamination, to the Potomac-Raritan-Magothy aquifer system in Gloucester County, New Jersey, extends a maximum of 0.5 to 2 miles downdip from the outcrop area as determined by use of a finely discretized ground-water-flow model and flow-path simulation by use of particle-tracking analysis. The areas contributing water to three water-supply wells, determined by simulation, were found to contain chemical-product-manufacturing or petroleum-refining land use. A relatively short minimum travel time of 30 years between the petroleum-refining land use and one of the wells indicates that contamination by volatile organic compounds is likely. The minimum traveltimes of greater than 50 years to the other two wells indicate that, to date, contamination by volatile organic compounds is not likely. These interpretations are consistent with available water-quality data. The results of the analysis also indicate that the two wells heretofore unaffected by contamination probably will be affected by contamination in the future and that the concentrations of volatile organic compounds in water from the affected well are likely to increase. The method of analysis used in this investigation could be applied to other locales provided that a finely discretized ground-water-flow model and high-resolution land-use data are available.