A COOPERATIVE EFFORT TO REMEDIATE A HISTORICAL
PCB DISPOSAL SITE
Marshall K. Sonksen, Staff Environmental Engineer
Aluminum Company of America
Davenport Works
Davenport, Iowa 52808
David V. Crawford, Sanitarian
United States Environmental Protection Agency, Region 7
Kansas City, Kansas 66101
INTRODUCTION
Alcoa is one of the largest producers of aluminum and aluminum products in the world. Started in
Pittsburgh, Pennsylvania in 1888, Alcoa now has mining, fabricating, and related businesses located
throughout the world. Its primary activities have included mining bauxite, producing alumina and
related chemicals, and fabrication of aluminum products. Recent decentralization and diversification
activities, however, have expanded Alcoa's interests into such integrated areas as waste and water
treatment, ceramics and associated composite materials, and various non-metal packaging materials.
One of Alcoa's primary aluminum fabrication facilities is its Davenport Works which was constructed along the banks of the Mississippi River in Davenport, Iowa in 1947. The plant, over a mile
long with 120 acres under roof, produces well over one million pounds of aluminum plate, sheet, and
foil each day. Diversified products from the Davenport facility can be found on space shuttles and
satellites, incorporated in auto bodies and truck trailers, and such familiar packaging products as
soda, cereal, and cigarettes.
BACKGROUND
Major waste streams for an aluminum hot and cold rolling mill are spent rolling oils, hydraulic
fluids, and oily wastes from routine pumping of pits. Prior to 1956, sludge and residual from the
chemical treatment of these wastes at Davenport Works was accumulated in concrete lagoons for
disposal. In 1956, due to insufficient space in the original concrete lagoons, a larger surface impoundment was created in a vacant area south of the plant. It was located in a natural depression in silty
clay. As with most surface impoundments constructed during that period, no artificial liner was used.
However, the south and west sides were constructed of compacted dikes with clay cores installed to
limestone bedrock which was located 10 to 20 feet below grade.
Prior to 1966, operation of the lagoon consisted of draining water off the bottom into the Mississippi River and removing free oil from the top for alternate ingot plant fuel. Beginning in 1966, this
water was returned to the chemical treatment plant for processing prior to discharge. A pair of million
gallon tanks were also installed to promote faster removal of the oil and reduce the size of the lagoon
which, by this time, had grown to nearly 14 acres. In 1976, a new $1.5 million ultrafiltration waste
treatment plant was installed that reduced the amount of sludge generated by nearly 80%. By 1979,
efforts to eliminate the lagoon had succeeded in reducing its size to approximately 2.5 acres.
THE PROBLEM
In 1979, Alcoa discovered that material in the lagoon contained polychlorinated biphenyls (PCBs).
Following extensive laboratory and field testing, the pumpable liquids were removed from the lagoon
to a PCB disposal facility permitted by the Environmental Protection Agency (EPA). The remaining
sludge was solidified with nearly 17,000 tons of cement kiln dust. This work was completed in
December 1981. In addition to this effort, an extensive network of monitoring wells was installed
around the site to evaluate groundwater quality.
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