HEALTH CONSULTATION
DU QUOIN GAS PLANT
(a/k/a DUQUOIN MANUFACTURED GAS PLANT)
DU QUOIN, PERRY COUNTY, ILLINOIS
BACKGROUND AND STATEMENT OF ISSUES
The Illinois Environmental Protection Agency (IEPA) requested that the Illinois Department of Public Health evaluate the DuQuoin Manufactured Gas Plant (MGP) for any public health issues. MGP site is an 8-acre area along Gas Plant Road on the southern edge of DuQuoin, Illinois, in Perry County (Attachment 1). The site is an abandoned town gas manufacturing facility operated in the past by both Central Illinois Public Service (CIPS) and Commonwealth Edison (ComEd). The Illinois Central Railroad borders the western site boundary; a commercial shopping center development borders the eastern boundary. Farm land is north of the site, and a residential area is south of the site. The nearest home is approximately 400 yards south of the site.
MGP began operations as a coal gasification plant in 1923 and continued until 1946 [1]. The processes at MGP involved reacting coal with steam to create gas for heating and lighting homes and businesses. Facilities at the site included gas generators, gas holders, gas purification facilities, and tar processing facilities. A 1927 map of the area shows four iron/tar purifiers, two tar processors, two oil tanks, and one tar tank on the site [1]. After tar separators removed tar particles from the gas, the purifiers removed hydrogen sulfide and hydrogen cyanide from the gas. This was accomplished by passing the gas through a mixture of iron oxides and wood chips. The tar processors dehydrated the tar by-products. The entire process resulted in several wastes including ash, slag, clinkers, coal tar, sludge, spent iron oxide wastes, and wood chips. Some by-products were salvaged and recycled. Wastes that were not recycled were placed in a lagoon on the northern portion of the site and various ditches on the site.
In 1986, IEPA initiated a remedial investigation at the site. Shallow soil borings performed then identified cinder fill material in the upper 2 feet of the soil throughout the site. The fill was oily in some places and contained coal and brick fragments. A noticeable chemical odor was described and the oily material was visible at the soil surface in many areas. Coal tar was found approximately 2 feet thick in the lagoon area. Wood chips treated with iron oxide were identified in the northwestern portion of the lagoon. The area south of the lagoon also contained coal tar and cinder waste.
In 1987, three shallow (17-feet deep) on-site groundwater monitoring wells were installed. Two additional wells were installed in 1988, one up-gradient and one down-gradient. The up-gradient well was off the site, southwest of the southern site boundary. Groundwater samples did not contain any contaminants at levels above comparison values used to select contaminants that may be of concern if people are exposed to them. Groundwater at the site flows northeast. No residential wells were identified near or down-gradient from the site.
The site remained unfenced and accessible to the public until the late 1980s. In 1988, a chain-link fence was installed around the site boundaries. Much of the site was overgrown with weeds and small trees. Major features on the site included the shallow coal tar lagoon, a concrete tank pad, and three buildings (Attachment 2). The buildings were in the southwest portion of the site. CIPS used one building as a garage. An electrical/plumbing contractor used the other two buildings as a machine shop and storage facility. The storage building has been demolished. The largest building formerly housed a storage area and the boiler, compressor, and exhauster rooms. A chain link fence now surrounds each building. Drainage ditches are on the eastern and western boundaries of the site. A small, intermittent, unnamed creek flows in a westerly direction across the northeastern part of the site. The intermittent creek, which drained the coal tar lagoon and the western drainage ditch, flows off the site at the northwest corner, eventually joining Half Mile Creek about 0.3 miles north. Half Mile Creek merges with the Little Muddy River approximately 5.5 miles south of the site [2].
Laboratory analysis of tar and wood chip waste samples, sediment samples, and soil samples collected on the site identified polycyclic aromatic hydrocarbons (PAHs) as the primary contaminants present. PAHs are commonly identified contaminants associated with crude oil, coal, and gasoline. They are produced whenever substances are burned and also are present in products made from fossil fuels, such as coal-tar, creosote, and asphalt. Benzo(a)pyrene (BaP) is one of the most potent PAHs and probably the most studied. Little is known about the potential health effects related to many of the other PAHs. To estimate the potential human health effects from exposure to the complex mixture of PAHs, toxicity equivalency factors (TEFs) for many PAHs have been developed based on the compound's toxicity compared with BaP [3]. The total TEFs for all the PAHs detected in the soil samples for this site were compared with the BaP value.
A BaP equivalent concentration of 5,063.67 parts per million (ppm) was detected in the coal-tar sample collected on the site near the coal-tar lagoon. Soil samples collected from 0-12 inches and soil samples collected deeper than 12 inches contained a maximum BaP equivalent concentration of 247.84 ppm and 8.78 ppm respectively. A maximum BaP equivalent concentration of 4,651.61 ppm was detected in sediment samples [1]. Sediment samples were collected from the drainage areas and the intermittent creek that flowed across the northeastern portion of the site. The highest concentrations of sediment contamination were found in the western drainage area that received effluent from the lagoon area.
Benzene, a volatile organic compound (VOC), was also detected in the coal-tar sample at 370 ppm. Surface soil samples contained a maximum benzene concentration of 6.2 ppm. A maximum benzene concentration of 73 ppm was detected in sediment samples [1]. No other VOCs were detected at levels above comparison values.
Air samples were collected in May 1987 at three different locations on the site: one upwind of the lagoon; one downwind of the lagoon; and the third in the center of the lagoon. The samples were analyzed for PAHs and VOCs including benzene, toluene, ethyl benzene and xylene (BTEX). None of those contaminants were present above detection limits [1].
In January 1997, CIPS and ComEd contracted PDC Response, Inc., to remediate the impacted soils at the site. The remediation included removal of the coal tar and wood chips from the lagoon area for management off the site. The materials were transported by truck to a hazardous waste landfill. The contaminated sediment was removed from the drainage ditch and replaced with clean soil. All other impacted soil was removed and replaced with clean soil. The contaminated soil and sediment were placed in the excavated lagoon area where it was stabilized with a cement mixture. The lagoon was then covered with a clean soil fill [5]. A 6-inch clay cap was placed on all remediated surfaces. The excavation and remediation were completed in April 1997. Prairie grass and flowers were planted throughout the remediated property and bluebird and kestrel nesting boxes were placed on the site [6].
Perimeter air monitoring was conducted before and during remediation activities. Of particular concern was the commercial strip mall next to the eastern boundary and the residential development south of the site. Before site remediation began, air samples were collected for five, 24-hour periods. During remediation, air monitoring was performed whenever excavation and stabilization of impacted soils occurred. Wind direction was recorded daily with the downwind sample station selected for analysis. Emissions measured included PAHs, BTEX, and total suspended particulates.
Total PAH and BTEX concentrations generally measured at or below detectable limits during pre- and post-remediation; however, during remediation, both increased on February 10, 1997, and fell several days later. Of the PAHs, phenathrene was detected most frequently, although acenaphthylene was detected at the highest concentration of 2.55 micrograms per cubic meter (µg/m3). BaP was not detected in any of the samples. Of the BTEX group, benzene was detected at a maximum concentration of 1,456 µg/m3. The elevated air concentrations corresponded to excavation and stabilization activities at the northern lagoon area. Elevated air concentrations were also detected in early March. This corresponded to the south hot spot excavation, southwest hot spot excavation and soil stabilization, and west side and railroad hot spot excavations. Total suspended particulate values showed an upward trend during that time also, but peaked in late March as backfilling was completed (Attachments 3, 4 & 5)[7].
On February 13, 1997, Illinois Department of Public Health (IDPH) staff visited the site. Remediation activities were ongoing at that time. Air monitoring activities were discussed and monitoring stations were noted. The on-scene safety officer said that besides the ambient air monitoring stations, periodic air samples were collected with Drager tubes to monitor benzene concentrations for worker safety. Workers involved in the excavation work wore protective clothing and were working with supplied air. In addition, the fresh air intakes on the air handling units for the commercial strip mall next to the site were closed and covered for the duration of the remediation.
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