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Congressional District # 03


EPA ID# ILN000510194
Last Updated: March, 2015

Site Description

The 15.5 acre Throop Street Station former Manufactured Gas Plant (MGP) site  is located at the intersection of South Throop Street, South Eleanor Street, and West 25th Street in Chicago, Cook County, Illinois.  The site is bounded to the north by the South Branch of the Chicago River, to the south by South Eleanor Street and West 25th Street, to the west by Loomis Street, and to the east by Commonwealth Edison property.  The western portion of the site was part of the former South Station MGP site but is included in the Throop site because of the common ownership and use.

Land use near the site is predominantly industrial and residential.  The site is currently owned by Brandenburg Demolition, Inc. (Brandenburg) and is used as a storage yard for equipment and debris.  Office buildings, tractor trailers, cranes, construction material, and debris associated with the demolition company are located on-site.  Much of the site is covered in crushed rock and gravel.  Although environmental conditions at the site have not been thoroughly investigated, surface staining has been observed; this staining may be associated with Brandenburg’s operations or with the previous MGP operations. 

The Throop Street Station was constructed in 1892 by Consumers Gas Company as a gas holder facility. MGP structures at the site included three gas holders (with capacities of 4.2 million, 5 million, and 10 million cubic feet) and associated underground water tanks, aboveground tar and oil tanks, exhaust holders, and boiler and pump houses. The Peoples Gas Light and Coke Company (“Peoples Gas”) acquired the site in 1897.  The site operated as a manufactured gas storage and distribution facility.  In 1944, a mixing plant was constructed to mix manufactured and natural gas on-site.  The 4.2 million cubic foot gas holder was retired from service in 1954 and dismantled in 1957. The 5 million cubic foot gas holder was retired by 1963 and the 10 million cubic foot gas holder was retired in 1971.  The station was closed in 1972 and sold in 1981.  All above ground structures associated with the gas holder facility have been demolished.

The Throop Street Station site is being addressed under EPA's Superfund Alternative (SA) site program.

Site Responsibility

The Throop Street Station MGP site is being addressed through potentially responsible party (PRP) actions under federal and state oversight.

Threats and Contaminants

Peoples Gas installed two soil borings in the southwest corner of the site in 2002 and observed black stained soils exhibiting strong odors beneath the water table and a sheen on the groundwater surface.  The general direction of groundwater flow at the site is expected to be north toward the South Branch of the Chicago River.  Contaminants present in groundwater and soil at the site include the volatile organic compounds (VOCs) benzene, toluene, ethylbenzene, and xylene (BTEX), and polyaromatic hydrocarbons (PAHs).  

The site is adjacent to the South Branch of the Chicago River.  Sediment samples were collected from a location in the South Branch approximately 750 feet downstream of the site (adjacent to the South Station former MGP site) in 2000 as part of an EPA study of sediment contamination.  These samples contained high levels of PAHs, polychlorinated biphenyls (PCBs), oil and grease, and metals; the concentrations of these substances generally increased with depth. Many of the reported concentrations of total and individual PAHs, PCBs, and metals suggest toxicity to organisms that live in the sediment (benthic invertebrates).  Peoples Gas sampled the sediment in 2006 and found tar-like impacts in a number of the sediment borings.

Cleanup Progress

In 2005, EPA was approached by Wisconsin Public Service Corp. (WPSC) with a request to investigate and clean up seven former MGPs throughout Wisconsin under EPA’s Superfund Alternative site (SA) program.  The SA program addresses cleanup sites, which might otherwise be eligible for the National Priorities List (NPL), and has them investigated and cleaned up by a cooperative PRP without formally listing the site on the NPL.  WPSC later merged with Peoples Energy to form Integrys Energy Group and EPA was then approached by Integrys in 2007 to address an additional thirteen former MGPs in Illinois, two in Waukegan and eleven in Chicago, under the SA program.  The Throop Street Station MGP site is one of the thirteen Illinois MGP sites.

EPA and Integrys entered into an Administrative Order on Consent (AOC) for Remedial Investigations and Feasibility Studies at the two Waukegan sites and an AOC for Engineering Evaluations and Cost Analyses (EE/CAs) at the eleven Chicago sites.  Since all twenty MGP sites have similar conditions and contaminants, and Integrys is the PRP for each, the agreements allow a streamlined approach to site investigation and remedy development. Some benefits of the agreement include the use of multi-site documents, a mechanism to review the adequacy of past work, and scheduling flexibility to allow progress on the "worst problems first."  By the end of 2008, all of the multi-site documents had been approved, and site-specific work had begun on several of the sites. On October 31, 2008 EPA and Integrys entered into an AOC which converted the EE/CA AOC for the 11 Chicago former MGP sites to an remedial investigation and feasibility study (RI/FS) AOC.

To more effectively manage all eleven Chicago-area MGP sites, the RI/FS AOC organized them into 4 sites: the North Shore Avenue Site, the North Branch Site, the South Branch Site. and the Crawford Site.  Both the North Branch Site and the South Branch Site have several operable units. The North Branch Site is comprised of the Division Street Station Operable Unit (OU), the North Station OU, and the Willow Street/Hawthorne Avenue Station OU. One site is the the North Shore Avenue Station Site. The South Branch Site is comprised of the 22nd Street Station Upland OU, the Hough Place Station Upland OU, the Pitney Court Station Upland OU, the South Station Upland OU, the Throop Station Upland OU, and the South Branch River OU.

Investigations and Remediation Previously Performed

Initial on-site environmental investigations were limited to a few borings in the southwest corner of the site in 2001-2002.  Conditions in the river adjacent to the site were investigated by installing borings at selected locations in 2006.  Evidence of tar impacts (tar globules, sheen, and odor) was observed at a number of sediment boring locations.  Data obtained with a tar-specific green optical screening tool (“TarGOST”) device indicate the presence of coal tar at several locations, and laboratory analyses of sediment samples found high levels of PAHs.

EPA approved the RI work plan for Throop Street Station in December 2012 and field sampling work began in spring 2013.  At least 4 rounds of groundwater sampling was collected by summer 2014.  In October 2014, Integrys submitted an RI summary report to EPA for review and approval.  A draft RI report is expected by fall or winter 2015. 


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



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