Area of influence and zone of contribution to superfund-site wells G and H, Woburn, Massachusetts

Abstract

Groundwater contamination by chlorinated volatile organic compounds detected by the Massachusetts Department of Environmental Quality Engineering in 1979 forced the closing of public supply wells G and H in the City of Woburn, MA. The EPA has ranked the wells G and H site on the National Priorities List as a CERCLA (Superfund) site and currently is conducting a feasibility study to determine a remedial action cleanup plan for the site. A 30-day aquifer test was conducted to determine the hydraulic properties of the stratified drift aquifer in the vicinity of the wells, and to determine the area of influenced and zone of contribution to wells G and H under pumping conditions. The area of influence of wells G and H described in this report is considered to be a snapshot representative of the hydrologic and pumping conditions of the 30-day aquifer test. Most of the water pumped by the wells is obtained directly from the part of the aquifer immediately surrounding both wells and from induced infiltration of surface water from the overlying river and wetland. The remaining part of the zone of contribution is that area of the Aberjona River drainage basin upgradient and outside the area ofmore » influence of wells G and H. A small amount of the surface water in the river entering the northern end of the study area, which is derived from groundwater discharge and surface water runoff in the up-gradient drainage area, is induced from the river to the wells under pumping conditions. The size of the area south of wells G and H that contributes water to the wells is variable, dependent on pumping rates and hydrologic conditions. 14 refs., 6 figs., 1 tab.« less