EPA 5 Year Review Peoples Nat'l Gas Superfund
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Region 7
Iowa
Kansas
Missouri
Nebraska
Fact Sheet
September 2005
Second Five-Year Review Completed
Peoples Natural Gas Superfund Site, Dubuque, Iowa
Introduction
.
The U.S. Environmental Protection
,.. . .
Agency (EPA) conducts regular five-year
reviews on Superfund sites where
cleanups have been conducted. These
reviews are required by the Superfund
law [42 U.S.C. 9 9621 (c)]. EPA Region 7
has completed the second five-year
review of the Peoples Natural Gas site in
Dubuque, Dubuque County, Iowa.
Site Background
The site is the location of a former coal
gasification plant which manufactured gas
from approximately the 1930s to 1954.
Production ceased when natural gas was
introduced to the community. During the
operation of the plant, waste products,
such as coal tar were generated and
disposed at the site. The coal tar
contained several hazardous substances
that contaminated the soil and ground
water at the site. Volatile organic
compounds, such as benzene, and
polycyclic aromatic hydrocarbons (PAHs)
were present in the soil and ground water
at levels that could harm people if they
were to come into contact with them.
The site occupies approximately five
acres and is located between East 11 th
Street and Kerper Boulevard,
approximately one-fourth mile east of
downtown Dubuque in an industrial area
near the Mississippi River. The city of
Dubuque owns the eastern portion of the
site and operated a public works garage
on the property. Highway 61 was
constructed on the western portion of the
site after contaminated soil was removed
from that area and treated off site.
Following the completion of a remedial
investigation and feasibility study, and an
opportunity for public comment on the
proposed remedy for the site, the EPA
presented the selected remedy in a
Record of Decision (ROD). The selected
remedy included the following actions:
· excavation and treatment of
contaminated soil and coal tar;
· extraction and treatment of
contaminated ground water in the silty
sand and alluvial aquifers; and
· in situ bioremediation of contaminated
soil and ground water;
During the design of the ground water
extraction and treatment system, it was
determined that extracting water from the
deeper of the two aquifers (the alluvial
aquifer) would result in contamination
being pulled down from the more heavily
contaminated silty sand aquifer. The
ROD was modified, through an
Explanation of Significant Differences
(ESD), to provide for monitoring, rather
than extraction, of ground water from the
alluvial aquifer. A second ESD modified
the clean up levels for benzene and
napthalene to the current federal
regulations.
In December 1992, a Consent Decree
was finalized with Midwest Gas (currently
known as MidAmerican Energy
Company), Enron Corporation, the city of
Dubuque, and the Iowa Department of
Transportation. They agreed to design
and perform the site cleanup.
MidAmerican Energy has conducted the
work at the site. Excavation and
treatment of contaminated soil and coal
tar was completed in 1998. Extraction
and treatment of ground water began in
1996. The system was shut down in 2003
due to problems with the operation of the
system. Studies are underway to
determine the best approach for dealing
with the contaminated ground water. The
in situ bioremediation system operated
from October 2000 through October 2002.
Periodic monitoring of ground water in the
silty sand and alluvial aquifers continues.
Five-Year Reviews
The first five-year review was conducted
in 2000. The site was found to be
protective of human health and the
environment.
The second five-year review determined
the remedy remains protective of human
health and the environment in the short-
term. To be sure the remedy will remain
protective in the long-term, the follow-up
actions listed in the report addressing
ground water contamination will need to
be implemented.
The follow-up actions include, among
other things, additional site investigation,
followed by a.focused feasibility study that
will evaluate alternative remedies for the
extraction and treatment system that is no
longer functioning. After the appropriate
remedy is determined, EPA will follow
with an amendment to the ROD.
The current deed restrictions on the
properties owned by the city of Dubuque
and the Iowa Department of
Transportation limit exposure to soil and
prohibit installation of drinking water wells
in the contaminated ground water plume.
However, these current restrictions may
not be enforceable as written and will be
replaced by enforceable environmental
covenants imposing the same limitations.
If the federal regulations on napthalene
toxicity standards change in the future,
EPA will modify action levels at the site if
warranted.
Additional Information
Detailed site information is available at
the following locations:
EPA Records Center
901 N. 5th Street
Kansas City, Kansas
Carnegie,-Stout Public Library
11 th and Bluff
Dubuque, Iowa
If you have questions or need more
information on the Peoples Natural C
Superfund site or the five-year review
process, please contact:
Fritz Hirter
Community Involvement Coordinator
U.S. EPA Region 7
901 North 5th Street
Kansas City, KS 66101
(913) 551-7003
Toll Free: (800) 223-0425
E-mail: hirter.fritz@eoa.qov
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