A daytime relocation program ended Wednesday for 11 families who returned home to the neighborhood surrounding the Van der Horst plant, the state's No. 1 Superfund clean-up site.
Unde a program that began July 28, families spent daylight hours at a local motel as a respite from odors, dust and noise created by the removal of chromium from the former industrial site.
Chromium seeped from the plant's underground vats between 1940 and 1987 and mixed with groundwater and soils. The operation is the third round of state or federal environmental work undertaken there and at another Van der Horst plant in more than 10 years. The cleanup was complicated by dust and a greasy substance that appeared in the groundwater.
Officials later said the groundwater contained a weathered diesel fuel or kerosene from another source and tentatively traced the dust to passing diesel trains. Residents were alarmed by the fuel's odor as it evaporated from the surface of groundwater bubbling up in a deep excavated pit, and many complained publicly of ill effects.
After meeting with residents in late July health and environmental officials began more stringent air monitoring and reduced the odor by covering the groundwater with materials that soaked up some of the fuel.
Dan Gore of Spruce Street believes said Wednesday that he and his neighbors are not relieved to be back home.
"We don't feel secure. Until we raised our voices about this whole thing nothing was done to protect us," he said.
Gore said he and others who fear permanent health problems from airborne contaminants after excavation was started in May will continue to pressure the state Department of Health for blood screening for heavy metals -- in addition to a cancer cluster survey that has been requested by state officials.
"We were getting headaches and some even complained of lightheadedness," he said, adding residents believe the market value of their homes has been adversely affected.
Last week, contractors began pumping three million gallons of chromium-laden groundwater through an ion-exchange resin treatment system as the final stage of the cleanup before filling in the excavated area. The cleaned groundwater is then discharged into a Penn Avenue sanitary sewer where it travels through the city's wastewater treatment plant.
Marty Doster, regional engineer for the state Department of Environmental Conservation, said the project goal is to restore the aquifer resource to as clean a condition as possible so it can be used by the next generation.
"In our lifetime it will never come back to a usable condition," he said, adding it is hoped nature's restoration efforts will render it useful to the next generation.
Doster said the relocation cost the state Superfund an estimated $20,000. In addition, cleanup costs at Plant No. 1 reached $6 million by July 1, with other outstanding costs yet to be paid for. Final cleanup costs at Plant No. 2 were $3 million and at least $500,000 was spent on a federal Environmental Protection Agency emergency response action after 1987, he added.
City Public Works Director Peter Marcus said he has looked at lab records and visited the site repeatedly and is satisfied that all but very minimal levels of fuel and chromium have been removed from the groundwater.
He said Wednesday that the process will probably continue another six weeks, somewhat longer than originally estimated. He said he is confident the city's wastewater treatment plant will not be harmed.
But Marcus said questions have arisen about the concentrations of chromium that will remain underground and were untouched by the cleanup. He also pointed to the long-term potential for the groundwater to travel along its natural course to the southwest to reach the city's water wells 1 1/2 miles away.