Introduction
During summer 2000, the U.S. Environmental Protection Agency (USEPA) began an investigation of the Tremont City Landfill Site near Tremont City, Ohio. The site is about 1 mile west of Tremont City, just south of the Clark-Champaign County line. The closed site consists of three main areas: an 8.5-acre barrel fill, a 14-acre waste-transfer area, and a 58-acre landfill. The local hydrogeology is complex, and multiple ground-water-flow directions at the site have been described; however, offsite ground-water levels and flow directions were poorly defined, because they were based on static water levels reported over many years by well drillers. In October 2000, the U.S. Geological Survey (USGS), in cooperation with the USEPA, measured water levels in residential and onsite monitoring wells to prepare a map of the potentiometric surface so that directions of regional ground-water flow could be better delineated in the vicinity of the site.
The topography of the study area (extent of map) is characterized by a nearly level till plain with minor relief along incised streams draining east-southeast to the Mad River. The Tremont City Landfill Site is in an upland area between two east-southeast-trending streams. Storms Creek is about 1 mile north of the site. The southern extent of the landfill is within about 500 feet of Chapman creek.
The surficial geology of the study area consists of unconsolidated glacial sediments that overlie Silurian-age Lockport Dolomite. These glacial sediments consist of fine-grained till interbedded with layers of silt, sands, and gravels. Sand and gravel layers are commonly found just above the bedrock surface. Onsite monitoring wells have been installed into several thin, permeable zones in the glacial sediments. Most residential wells in the area produce sufficient water for residential use (as much as 100 gallons per minute), from either sand and gravel layers in the glacial sediments or from the carbonate bedrock. The most productive aquifer in the area is the highly permeable glacial outwash in the buried bedrock valley beneath the Mad River. These outwash sands and gravels can yield more than 1,000 gallons per minute. If weathered, the Lockport Dolomite can be a productive source of water near the top of the unit.
