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Congressional District # 04


EPA ID# WID039052626
Last Updated: March, 2015

Site Description

The 88-acre Moss-American Superfund site is located in Milwaukee, Wisconsin.  In 1921, the T.J. Moss Tie Company established a wood-preserving facility west of the Little Menomonee River in Milwaukee and the plant reportedly treated wooden railroad ties, poles, and fence posts with creosote, a preservative that consists of a mixture of numerous chemical compounds derived from coal tar, and No. 6 fuel oil, but not with pentachlorophenol. (Operations at a creosote plant typically include storage facilities for both creosote and fuels; a boiler used to make steam to heat the creosote and aid in application to the wood through usage of heat and pressure; unloading, storage, and transportation of incoming timbers to the creosote application facility; and subsequent storage of treated timber in a drying area. After these processes were completed, the treated timbers would then be shipped to customers. Potential for release of contamination exists throughout the storage, application, and drying processes.)

For a time, the Moss facility discharged wastes to settling ponds that discharged to the river. The discharges later ceased when the plant diverted its process water discharge to the Milwaukee sanitary sewerage system.  Production at the facility ceased in 1976.

In September 1984, the United States Environmental Protection Agency (EPA) placed the Moss-American (Kerr-McGee Oil Co.) site on the Superfund National Priorities List.

Site Responsibility

The Moss-Amercian site is being addressed under a combination of federal and state actions and by potentially responsible party (PRP) actions under federal and state oversight.

Threats and Contaminants

Groundwater samples taken at the Moss-American site showed elevated levels of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs).  Free-standing creosote or an oil sheen was observed in three monitoring well samples; similar observations were noted in eight test pits dug at the site.  Contaminants that were found in the soil in the processing area and vicinity, the treated wood storage area, and the northeast and southeast landfills include components of creosote: PAHs and benzene, ethylbenzene, toluene, and xylene (BTEX compounds).  PAHs were detected in a ditch that drains water from the site to the Little Menomonee River and have been detected in river sediment.

Potential health risks exist for individuals inhaling volatilized chemicals or ingesting or coming into direct contact with the contaminants in the river sediment, and site soil, groundwater, or surface water.  Both carcinogenic (cancer-causing) and noncarcinogenic health effects could occur if people were to be exposed to PAH compounds.

Cleanup Progress


EPA conducted a remedial investigation and feasibility study (RI/FS) at the site in 1987 to determine the nature and extent of contamination (RI) and to analyze potential cleanup alternatives (FS). EPA selected a cleanup action in a 1990 Record of Decision (ROD) and then entered into negotiations with the former site owner/operator, Tronox LLC (formerly Kerr-McGee), to implement the selected cleanup action at the site.  On December 30, 1991, the U.S. Department of Justice (DOJ) lodged a remedial design (RD)/remedial action (RA) consent decree (CD) with the Federal District Court in Milwaukee for comment. The agreement called for Tronox to implement the remedy as set forth in the 1990 ROD. The CD was entered by the court in March 1996. Parties bound by the decree include EPA, the Wisconsin Department of Natural Resources (WDNR), and Tronox.

The construction schedule for the cleanup was outlined in the RD/RA workplan contained in the CD. Based on predesign sampling results, EPA requested that priority be given to removing the free product (creosote) in the groundwater and directed Tronox to design the groundwater collection/treatment portions of the cleanup project first. From 1995 to 1997, approximately 10,000 gallons of free product and related wastewater were collected and removed from the site. In April 1997, EPA and WDNR approved the use an innovative in situ funnel-and-gate process as a means of managing site groundwater. The in situ funnel-and-gate approach utilized air and nutrient injection into the groundwater to promote biological degradation of dissolved contaminants. Construction of the funnel-and-gate system began in 1999 and was completed in July 2000.

In 1998, EPA, with the concurrence of WDNR, modified the soil cleanup plan in the 1990 ROD to allow for treatment of the most highly contaminated soils via the thermal desorption technique to reach commercial/industrial cleanup standards, provided that Tronox placed the appropriate deed restrictions on the property.  The deed restrictions were filed in 2000, and Tronox also completed the RD of the thermal desorption action that year.  After the soil treatment work was completed in early 2002, a total of 137,000 tons of contaminated soil had undergone treatment.

In early 2002, RD plans for management of contaminated sediments in the nearby Little Menomonee River were submitted to EPA for approval. After RD approval in August 2002, EPA conducted a public availability session in September 2002 to discuss the pending cleanup work.

Five reaches of the river were affected, and remedial work was conducted in phases. River Reach 1 stretched from Brown Deer Road to Bradley Road.  For most of this length, a new river channel was created slightly east or west of the existing channel and water flow was diverted into it.  Contaminated sediment was then removed from the dewatered former channel and then the former channel was filled in with soil that was excavated from the new river channel. 

In 2003, similar design plans were completed for River Reaches 2 and 3, which extend from Bradley Road to Good Hope Road then to Mill Road. Cleanup actions in these reaches of the river were completed December 30, 2004, which also included the development of aquatic habitat.  River sediment management for River Reaches 1, 2, and 3 is now complete.

Progress to date

On October 31, 2008, Tronox submitted a work plan for cleaning up the final reach of the Little Menomenee River (Reach 4/5), which EPA approved on March 4, 2009.  In January 2009, Tronox declared Chapter 11 bankruptcy and informed EPA in April 2009 that it would temporarily suspend the remaining work at the site. Subsequent to this decision by Tronox, EPA decided to finish work on Reach 4/5 using Superfund monies.  Tronox is no longer continuing its responsibilities under the CD after settlement of the Chapter 11 bankruptcy case in 2010, with an approved bankruptcy reorganization plan entered in court on 2012. 

On August 3, 2009, EPA began work at Reach 4/5, which was completed in November 2009.  EPA issued a preliminary construction completion report on November 25, 2009 to document that construction of the remedy components were completed.  WDNR is now responsible for conducting semiannual and annual groundwater monitoring as well as other operation and maintenance duties.

In July 2011, EPA began some minor site restoration work, which included the removal of excess material (pipes, tubings, fencing, concrete barriers, etc.), excavating and off-site disposal of soil/asphalt/gravel used in road-building, and regrading of two soil piles and a 1/4-mile temporary access road. This work was completed in September 2011.

In 2012, EPA and WDNR entered into a cooperative agreement (CA) for implementing recommendations to optimize the existing groundwater treatment system.  WDNR will lead this effort, with EPA providing funding to conduct the work. In 2013-2014, WDNR completed the first phase of the optimization work, which was to collect soil and groundwater samples at the site. In 2015, WDNR expects to start the second phase of the project which involves implementing recommendations from its contractor on addressing the continuing exceedances of groundwater contamination at certain wells in the monitoring well network. 

Five-Year Reviews 

On March 18, 2015, EPA completed the fourth five-year review (FYR) of the site.  The 2015 FYR report recommended, among other things, that long-term stewardship procedures be implemented at the site, along with implementing response actions for optimizing the groundwater treatment system, as recommended in the 2011 Corps of Engineers remediation system evaluation (RSE) report. 

Property Reuse

Milwaukee County (65%) and the Union Pacific Railroad (35%) own the majority of the Moss-American site.  Tronox owned a small sliver of property in the northeast corner of the site that was not associated with past operations.  Some interest was expressed in re-using the Tronox parcel, but no progress is noted to date.


Remedial Project Manager, U.S. EPA
Rosauro Del Rosario (delrosario.rosauro@epa.gov)
(312) 886-6195

Community Involvement Coordinator, U.S. EPA
susan pastor
(312) 353-1325




Site Profile Information

This profile provides you with information on EPA's cleanup progress at this Superfund site.


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