Trace Metals in Ground Water at Prime Hook National Wildlife Refuge, Delaware
WRD PROJECT #: MD156
PROJECT CHIEF: Soeder, Daniel J.
BEGIN DATE: 01-Oct-2000
END DATE: 30-Dec-2001
Customers currently supporting the project:
U.S.
Fish and Wildlife Service
U.S. Geological Survey
Problem
The Prime Hook National Wildlife Refuge near Georgetown, Delaware is adjacent to the Broadkiln Gun Club and skeet shooting range that was in operation for approximately 40 years. During this time, shot that contained lead and possibly other metals was deposited onto the grounds of the shooting range and adjacent land in the Prime Hook reserve. The shooting range was shut down in 1999, but lead shot is still present in the surface and shallow subsoil. The USEPA and USFWS personnel are trying to assess the potential environmental risks and have detected lead in the surface waters and soils surrounding the facility.
Objectives
The major objectives of this study are to
- Develop a ground-water sampling network for lead, arsenic, and antimony in the vicinity of the lead shot source area.
- Determine if lead is in surface water including the slough area and Prime Hook Creek adjacent to the shooting range.
- Roughly configure the potentiometric surface and the hydrogeology of the shallow unconfined aquifer.
Approach
The USGS will install 10 shallow and 6 deep wells in addition to the original 7 wells that were sampled in June 2000. The wells will be installed using hand equipment or machinery that can be transported by foot, since the area of interest is inaccessible to vehicles. As each well is installed, the stratigraphy of the shallow aquifer will be documented. Four deep wells will be installed near the original shallow wells to provide "well nests" for investigation of vertical transport, and shallow-deep well pairs will be placed in the slough downgradient of the drop zone and near Prime Hook Creek. The additional 10 shallow wells will be installed at various locations around the lead-contaminated area to help define the plume boundaries, but complete definition of the plume boundaries may not be possible at this stage of the investigation.
The USGS will develop each borehole and collect samples for water chemistry in the spring of 2001. This time of year is selected because the high water conditions are such that lead is likely to be the most mobile. All samples will be analyzed for lead, antimony, and arsenic at the USGS National Water Quality Lab in Denver, Colorado, and selected samples will be made for pH, dissolved oxygen, temperature, and specific conductance.
