Introduction

A temporary structure called the Interim Storage Facility was built on the property of the WTTP to house contaminated material removed from other locations in Bloomington: the Anderson Road Landfill, stream sediments that were dredged from Clear Creek and Richland Creek, sludge from the WTTP digesters, and capacitors taken from various locations.

Twenty-three years after the PCB contamination was first discovered, the WTTP cleanup finally began and the site is now officially clean to the satisfaction of the government parties and the Bloomington community.

The complete cleanup of the WTTP site is the successful conclusion to many years of difficult negotiations between the government parties to the Consent Decree, Westinghouse/CBS and the Bloomington community. Remediation of the WTTP occurred in two phases: the 1987 Interim Remedial Measures (IRMs), and the 1997-99 Final Remediation Activities.

In 1987, Interim Remediation Measures prescribed bythe Consent Decree were completed. The IRMs included removing sediment along 1,100 feet of Clear Creek, constructing a security fence around the tertiary lagoon, and placing the excavated sediment in an Interim Storage Facility (ISF) on site. The ISF also housed PCB-contaminated solid waste resulting from IRMs at other locations in the Bloomington area.

Negotiations to remediate the entire WTTP site began in earnest in the mid 1990s. The components of the WTTP site that required cleanup included the 17-acre tertiary lagoon, abandoned lagoons, sludge drying beds, four digesters, a trickling filter, piping, structures, soil on-site and off-site, plus the contents of the Interim Storage Facility. In 1996, sampling activities, risk assessments and remedial work plans were produced. Remediation of the four digesters, three drying beds, piping associated with the digesters and drying beds, soil from east of the entrance road and soil from west of Clear Creek was performed in 1997. In 1998, remediation was performed on the abandoned lagoons, trickling filter, the perimeter of the drying beds, the south berm of the tertiary lagoon, the interior of Digester 4 was re-cleaned, and contaminated soil adjacent to Digester 4 was removed. Remediation of the 17-acre tertiary lagoon began in 1998 and was completed in the Fall of 1999. Each of these areas is discussed in the sections that follow.

Four anaerobic sludge digesters were used at the WTTP to process sludge prior to application on the three drying beds. The digesters are circular concrete structures 40 to 50 feet in diameter. In 1991, Westinghouse removed and treated 410,000 gallons of water that had accumulated in the digesters over the years. The solid waste that was generated during the treatment of this water was stored in the Interim Storage Facility. The sludge that remained in the digesters ranged in depth from 17 to 24 feet. Westinghouse began dewatering the sludge in the digesters in 1996 by pumping free liquids to an on-site treatment system. The free water was removed through 8-inch diameter well points equipped with submersible pumps. In 1997, OHM Remedial Services Corporation, under contract to CBS, removed approximately 62,600 cubic yards of sludge from the four digesters. Information describing some activities related to digester remediation (sludge removal and disposal, and spray washing the digesters) is not currently available to COPA. Forty wipe samples were collected from the interior of the digesters following pressure washing: OHM collected 8 samples, and EPA collected 32 samples. Three of the EPA samples exceeded the maximum allowable PCB concentration of 100 ug/ 100 cm². In 1998, PSARA inspected and resampled these three areas, and re-cleaned the interior of Digester 4 until the wipe samples were all below the acceptable limit. An area of soil adjacent to Digester 4 became contaminated during the sludge removal activities, and this soil was excavated until the PCB concentration was below 1 ppm.

OHM removed vegetation, sludge and contaminated sand from the sludge drying beds in 1997. Seven of the 17 soil samples collected along the perimeters of the drying beds contained PCBs over 25 ppm, and two of these contained PCBs in excess of 100 ppm. More detailed information describing the 1997 remediation of the drying beds is not currently available, but will be added to this report when it becomes available. In 1998, soil was removed from the perimeters of the drying beds until the PCB concentration in post-excavation samples was below 25 ppm. Excavated soil was disposed of at the TSCA landfill in Belleville Michigan. During excavation along the perimeter of drying bed 1, dark material containing PCBs was found. This area, on the south berm of the tertiary lagoon, was excavated in 1998. All excavated areas were backfilled with clean soil, clay, or decontaminated stones from the trickling filter.

The abandoned lagoons covered 2 acres. Based on the results of sampling performed in 1996, remediation was required along the perimeter and in the interior areas of the lagoons. An intermittent creek was diverted 10-15 feet south during remediation of the abandoned lagoons, and was later restored to its original location. The lagoon area was divided into 25ft x 25 ft grids for excavation and post-excavation verification sampling. Where post-excavation composite sampling of a grid showed more than 25 ppm PCBs, additional 6-inch layers of soil were scraped until the grid composite concentration was below 25 ppm. The final concentration of PCBs in all grids was below 25 ppm, and the average of all grid composite samples in the abandoned lagoon area was 5.1 ppm, well below the maximum allowable concentration of 15 ppm. The abandoned lagoon area was covered with 9 inches of clean fill and 3 inches of topsoil.

All spring water and storm water collected during remediation of the abandoned lagoons was treated on site and discharged to the sewer, meeting the discharge criteria of 0.01 mg/l. The intermittent spring in this area was sampled twice, in October 1998 and May 1999,and contained PCBs on both occasions. Additional sampling will be performed, and the need for monitoring and treatment will be determined at a later date.

Four air monitoring stations equipped with PUF samplers were maintained during remediation of the abandoned lagoons. The highest reading was 787.8 ng/m³, below the maximum allowable limit of 1000 ng/m³.

Remediation of the 17-acre tertiary lagoon to below 1 ppm is the most significant accomplishment of the WTTP remediation effort. Cleanup began in 1998 and was completed in the Fall of 1999. The lagoon was dewatered and dredged, and the saturated sludge was dewatered and pressed into filter cake. The water was treated on-site to below 0.01 mg/l and discharged to the municipal sewer. The lagoon bottom was divided into 35ft by 35ft grids for excavation and post-excavation sampling. The original cleanup criteria called for the composite of four samples within each grid not to exceed 25 pm PCBs, and the average of all grid composites within the tertiary lagoon not to exceed 15 ppm. The lagoon was then to be covered with 6 to 12 inches of clean fill. However, midway through the remediation of the tertiary lagoon, Westinghouse/CBS chose to leave no more than 1 ppm PCBs in any area of the tertiary lagoon, eliminating the need for clean soil cover or deed restrictions of this area of the site. The scraped material that contained between 1 and 25 ppm PCBs was placed in the south berm of the lagoon. The south berm was then covered with 12 inches of clean soil. The sludge filter cake was disposed of at the TSCA landfill in Bellevue, Michigan. Additional information describing remediation of the tertiary lagoon has been requested, and this summary will be updated when that information becomes available.

The trickling filter consisted of a sub-grade concrete structure 280ft x 245ft in surface area, and extending 7.5 ft into the ground. It was equipped with a network of vertical and horizontal drains, and filled with angular limestone gravel 2-3 inches in diameter. The remediation of this unit involved removing all of the stones and piping from the trickling filter, and sorting this material into small diameter pipes, large diameter pipes, oversized stones, mid-sized stones and undersized stones. 23,851 tons of mid-sized stones were pressure washed on-site, and sampled to confirm that the PCB concentration on the surface of the stones was below 10 ug/100 cm². All stones met this treatment criteria with one cycle of washing. The decontaminated mid-sized stones were stockpiled in the former Drying Bed 1, and used as backfill in some locations on site. The debris produced during the stone washing process contained less than 10 ppm PCBs and was taken to the South Side special waste landfill in Indianapolis. The undersized stones were sampled and confirmed to be non-TSCA waste, and were also taken to the South Side landfill for disposal. 109 tons of small-diameter pipes were taken to the TSCA landfill in Bellevue, Michigan for disposal. The large diameter pipes were pressure-washed within the empty trickling filter. Information describing the ultimate disposal of these pipes has been requested and this report will be updated as appropriate. The walls and floor of the trickling filter was then pressure washed and wipe sampled to confirm that the PCB concentration on the surface was below 10 ug/100 cm². 45,000 gallons of process water plus 318,000 gallons of collected storm water was treated on site to below 0.01 mg/l PCBs, and discharged to the municipal sewer.

Information describing the remedial activities at the Interim Storage Facility is not currently available to COPA. This report will be updated when additional information is received.

Information describing the removal of soil east of the entrance road has been requested. This report will be updated when additional information is received.

The Action Memorandum called for the removal of 10,300 cubic yards of soil, down to a PCB concentration of 1 ppm, although up to 15 ppm could be left below at a depth of 18 inches Documents describing actual quantity of soil removed, and the PCB concentration of soil remaining at the site are not yet available to COPA. This summary document will be updated as information becomes available.

COPA has requested information concerning long-term monitoring of groundwater, surface water in Clear Creek, and soil cover in areas where soil cover was required. This document will be updated as appropriate when information becomes available.

To confirm that remediation at the WTTP plant is adequate and permanent, long term monitoring of groundwater and surface associated with the site is necessary.

Successful remediation WTTP is an important milestone for the Bloomington community. The removal of accessible PCB-contaminated soil, sediment, sludge, water and structures results in a dramatic reduction in risk to human health and the environment. However, it is important to recognize that the PCBs from this site have not disappeared. Some PCB contamination remains in the soil and bedrock under the site, and large amounts of PCB contaminated material are being stored in TSCA and industrial landfills. The landfills will likely provide adequate long-term containment of the PCBs, but the integrity of the landfill liners will degrade while PCBs remain in storage. Therefore, vigilant monitoring of the landfills for PCB releases, and prompt corrective action as needed, are essential for the continued protection of human health and the environment.