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| Publications— Scientific Investigations Reports |
In cooperation with the U.S. Environmental Protection Agency
U.S. Geological Survey Scientific Investigations Report 2006-5167
By Curtis L. Schreffler
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
View the full report in PDF 16.8 MB
Extensive remediation of the Drake Chemical Superfund Site has been ongoing since 1983.
Contaminated soils were excavated and incinerated on site between 1996 and 1999. After 1999, remedial efforts focused on
contaminated ground water. A ground-water remediation system was started in November 2000. The source area of the
contaminated ground water was assumed to be the zone 1 area on the Drake Chemical site. The remedial system was designed to
capture ground water migrating from zone 1. Also, the remediation system was designed to pump and treat the water in an
anoxic environment and re-infiltrate the treated water underground through an infiltration gallery that is hydrologically
downgradient of the extraction wells. A numerical ground-water flow model of the surrounding region was constructed to
simulate the areas contributing recharge to remedial extraction wells installed on the Drake Chemical site. The
three-dimensional numerical flow model was calibrated using the parameter-estimation process in MODFLOW-2000.
The model included three layers that represented three poorly sorted alluvial sediment units that were characterized
from geologic well and boring logs.
Steady-state ground-water flow was simulated to estimate the areas contributing
recharge to three extraction wells for three different pumping scenarios—all wells pumping at 2 gallons per minute, at
approximately 5 gallons per minute, and at 8 gallons per minute. Simulation results showed the contributing areas to the
three extraction wells encompassed 92 percent of zone 1 at a pumping rate of approximately 5 gallons per minute. The
contributing areas did not include a very small area in the southwestern part of zone 1 when the three extraction wells
were pumped at approximately 5 gallons per minute. Pumping from a fourth extraction well in that area was discontinued
early in the operation of the remediation system because the ground water in that area met performance standards. The
areas contributing recharge to the three extraction wells did encompass zone 1 at a pumping rate of 8 gallons per minute.
At pumping rates of 2 gallons per minute, the contributing areas for the three extraction wells did not encompass zone 1.
Abstract
Introduction
Purpose and Scope
Modeled Area
Previous Investigations
Geology
Simulation of Ground-Water Flow
Model Design, Layers, and Boundary Conditions
Model Layers
Model Boundaries
Calibration of Numerical Model and Errors
Model Limitations
Areas Contributing Recharge to Extraction Wells
Summary and Conclusions
References Cited
Appendix 1--Water-Level Hydrographs
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
View the full report in PDF 16.8 MB
For more information about USGS activities in Pennsylvania contact:
Director
USGS Pennsylvania Water Science Center
215 Limekiln Road
New Cumberland, Pennsylvania 17070
Telephone: (717) 730-6960
Fax: (717) 730-6997
or access the USGS Water Resources of Pennsylvania home page at:
http://pa.water.usgs.gov/.
