Project Summaries

Primary Client
Alliant Energy (AE) and Interstate Power & Light Company (an AE Company)
Cedar Rapids, Iowa

Mr. Dean A. Hargens

Project Summary
Energy Recovery and Cost-Effective Remediation of Manufactured Gas Plant Waste at a Fixed-Base Medium Temperature Thermal Desorption Facility.


DCI Environmental, Inc. (DCI), in cooperation with Iowa Power and Light Company (IPL) and its affiliates (Alliant Energy is the parent Company) implemented an innovative approach to manufactured gas plant (MGP) site remediation.  In the late 1990s, with the change in the characterization of MGP waste as hazardous, DCI, IPL, and MEC sought a cost-effective strategy for treatment of contaminated materials removed from their MGP sites.  It was ultimately determined that thermal desorption using DCIs mobile and fixed-based Medium Temperature Thermal Desorption (MTTD) systems was the solution.  In cooperation with the Iowa Department of Natural Resources (IDNR), DCIs fixed-based facility was set up at the Cedar Rapids, IA, USA, Bluestem Solid Waste Agency Landfill in 2001.  The facility successfully treated 395,866 tons of source materials and contaminated soil from over 25 MGP sites.  The facility used methane gas generated by the landfill to provide energy for the thermal desorption of MGP wastes.  Treated soil was typically used as daily cover at the landfill.

The processes required to get to the successful implementation of the thermal desorption facility, included facility siting, permitting and trial-burn requirements, fuel sources, material processing, treatment criteria, treated soil disposal, and the economies of scale.  The merits of energy recovery through the use of methane gas to power the unit and landfill conservation by using treated waste, as cover material was explored and employed.  It was demonstrated why USEPA Headquarters Washington, D.C. was quoted that ?this approach to energy recovery and cost effective remediation warrants replication.?


Future environmental liability has always been on the for-front of IP&Ls corporate mindset, therefore IP&L has limited the use of landfills for disposing of wastes from MGP sites.  Thermal desorption is commercially and technically capable of treating the wide range of waste types and contaminate concentrations that are present at MGP sites.


IPL has been identified as a potential responsible party (PRP) for 57 MGP sites.  The sites are located in six states: Iowa-33, Minnesota-6, Wisconsin-14, Illinois-2, Nebraska-1 and Colorado-1.  This cooperative effort concentrated upon IPLs Iowa, USA locations based upon IPL identifying 33 MGP sites that requiring some form of Interim Removal Action (IRA).

DCI Environmental, Inc. formerly Dustcoating, Inc. (DCI), was incorporated in 1977 to provide environmental services including, Low Temperature Thermal Desorption (LTTD) of petroleum-contaminated soils.  In 1993, DCI introduced a Medium Temperature Thermal Desorption (MTTD) unit to the Utility industry. 

Since 1988, IPL has completed several removal actions. These removal actions included the excavation, treatment and disposal of both TCLP hazardous and non-hazardous contaminated material. The treatment methodologies that have been utilized include co-firing with coal in utility boilers, use as a raw material substitute in cement kilns, combustion in hazardous waste incinerators, and Medium Temperature Thermal Desorption (MTTD) in fixed and transportable thermal desorption units (TDUs).

Since 1995, IP&L has worked with DCI to thermally desorb contaminated soil. In 1995, IP&L worked in cooperation with United States Environmental Protection Agency (USEPA) and IDNR to remediate the MGP site located in Mason City, Iowa, using MTTD.  This IPL site was the first MGP site in Iowa, USA to use the MTTD process and both Air Quality and Soil Cleanup requirements were established.  In 1999, IPL began working with DCI on the remediation of sites in Storm Lake and Chariton, Iowa.

In 2001, DCI and the Bluestem Solid Waste Agency (BSWA) entered into an agreement that allowed DCI to utilize a portion of the BSWA facility located in Cedar Rapids, Iowa, as a fixed base site for the accumulation and treatment of non-hazardous contaminated soil using its MTTD unit. The treated soil was used by BSWA for daily cover (an average of $10.00 US ton monetary value) at the landfill. IPL was the first utility to utilize the DCI Iowa fixed base facility when contaminated soil was transported to Cedar Rapids from a MGP site in Oelwein, Iowa.  


Linn County Siting Process
DCI was required to obtain County Board approval from County Commissioners.  What aided DCI during this process was the fact that DCI had temperately used the landfill for the treatment of an utility MGP site that was located in the City of Cedar Rapids which is where landfill is located.  During this project, there were no operational, administration, nor public concerns regarding past operations.  Furthermore, DCI paid a host community-tipping fee in which Linn County profited from during this project tenure.

Air Quality Use Permit

The MTTD unit operated under an Iowa Department of Natural Resources and a Linn County Air Quality Use permit.  DCI demonstrated annually, either a 99.99% Destruction Removal Efficiency (DRE) of Polynuclear Aromatic Hydrocarbons (PAHs) and a 99.7 DRE for Sulfurhexafloride (SF6).  The PAH DREs were measured based upon the PAH contamination level in the soils.  The SF6 was measured based upon spiking the MTTD unit with SF6 surrogate.  The SMF does not require a permit from USEPA in Region 7 however, was endorsed by USEPA Kansas City as DCI accepted other USEPA MGP project soils for treatment.

The IPL MGP site remediation that was conducted in conjunction with USEPA, Region 7, the MTTD operated at identical conditions throughout the required stack test and both, the PAH and the SF6 testing was performed by an independent third party (Interpoll Laboratories) to correlate the PAH and the SF6 DRE.  The outcome was when operating under the same conditions a 99.99 PAH DRE is equal to a 99.7 SF6 DRE.

Soils Management Facility Permit
The MTTD unit and its soils management operates under this permit in which is issued by the IDNR.  This permit identifies requirements for soils operational and administrative management including the soil acceptance and treatment criteria.  This permit also encompassed an Emergency Response Remedial Action Plan contingency. 

For beneficial reuse, the treated soil must meet IDNR treatment standards of less than 5 mg/kg total PAH and less than 100-ppm total petroleum hydrocarbons based upon composite sampling of 300-ton stockpile increments.

The DCI MTTD unit is located on a 300 by 600 foot area adjacent to the composting facility in the southeast corner of the landfill. The thermal system and contaminated soil are located on an impervious asphalt pad. The pad is sloped so that all water drains to a sump area where it is treated by activated carbon and discharged to the City of Cedar Rapids wastewater treatment facility.

Waste Water Discharge Permit
The DCI SMF operated under this permit in order to discharge treated run-on and run-off water from the Contaminated Soils Staging Area (CSSA) and the MTTD Plant Operations Area (POA).  The City of Cedar Rapids, Iowa USA dictated which compounds of concern treatment requirements to be achieved before discharge to the local sanitary disposal facility.


This project provided for the reuse of energy from a waste source to aid in the treatment of contaminated soil by using the gas generated at the BSWA landfill. Not only did this project reuse a recovered energy source but it also eliminates the need for second energy sources such as propane if quality, quantity and infrastructure for methane gas are available. Furthermore, the treated soil was used by the landfill as daily cover reducing the landfill's need to import soil. 

Addition utilities transporting MGP soils to DCI's SMF were as follows;

MidAmerican Energy Company (MEC)
Sioux City, Iowa
Ms. Michelle Wei / Kathy Willums

Kansas Gas Service (KGS) a Division of Oneok
Topeka, Kansas
Mr. Alan Kettle, P.E.