Industrial site cleanup, including groundwater extraction and treatment, began in the 1970s, and the EPA has continued to operate remediation systems for a Missouri National Priority List (NPL) site using pump-and-treat technology.
In 1990, a partnership formed to implement a plan for a groundwater extraction and treatment system to capture groundwater contamination from an industrial disposal site within the U.S. Environmental Protection Agency’s (EPA) Region VII. Twenty years later, that same team continues to operate the system according to plan, remediating the National Priority List site using pump-and-treat technology.
The environmental regulations initiated in the 1970s and ’80s launched many efforts to clean up industrial sites around the country, including the former home of the Conservation Chemical Co. along Front Street adjacent to the Missouri River in northeast Kansas City, Mo. From 1960 to 1976, a mix of hazardous and industrial wastes were treated and disposed of in six unlined basins. Leachate from the basins contaminated the groundwater beneath the site.
The Missouri Department of Natural Resources closed the site in 1976, and the top portion of the basins were stabilized and covered. The EPA began a remedial investigation in 1979, and the U.S. District Court signed a consent decree in 1988 outlining a containment plan. The Front Street Remedial Action Corp. (FSRAC) was formed at that time by four firms from among more than 200 waste generators: AK Steel, FMC, Alcatel Lucent and IBM.
The consent decree selected pump-and-treat groundwater remediation from more than 20 other methods studied, making it the first such system to be implemented in EPA Region VII. Burns & McDonnell, which had been the technical consultant for then-parent company AK Steel, was added to the team to prepare the conceptual design for a system to pump groundwater, treat it to remove metals and organic chemicals, and discharge it to the Missouri River. FSRAC was tasked with funding the design and construction of the containment system and its operation.
The Conservation Chemical site is small, with the six basins covering approximately 7 acres. As a result of site space constraints, including a levee and adjacent industrial businesses, the treatment plant would require a small footprint for the systems removing the more than 20 contaminant types identified.
“The proximity of the river and area geology also meant the contamination was unconfined on the site,” says Jeff Keller, Burns & McDonnell operations manager for the project since 2000. “The pump-and-treat design had to accommodate the changing water flow patterns intrinsic to the river environment.”
The FSRAC members knew from the beginning that operations would continue for an extended period. Any solution would need to be cost-effective and durable — one that would work smoothly for multiple decades.
The chain of liquid treatment processes were designed and sequenced within the plant to maximize effectiveness while minimizing plant size. The 11,000-square-foot facility has a mezzanine to elevate some systems, and the layout maximizes efficiencies.
“To draw the groundwater from below the site into the remedial wells to be pumped and treated, instead of migrating to the river, eight paired piezometer wells precisely measure the flow of groundwater from the area beneath and around the site into the two wells, drawing groundwater from depths of 90 to 100 feet,” Keller says.
The challenge to design and operate a facility that would pump and treat groundwater 24 hours a day for decades required vision and creative solutions, given that only one of the FSRAC members had local headquarters. “Burns & McDonnell was contracted to provide all necessary operations and maintenance services at the plant through our Facility Operations Services,” says Burns & McDonnell Associate Vice President Pete Zanoni, who has been part of the project since 1990. “Jim Henson, who provided construction and startup oversight, has supervised the treatment plant operations ever since.”
“It’s been an excellent working relationship over the years,” says Tom Morris, IBM environmental engineer and president of the FSRAC board. “There has always been a high level of attention to this project from the Burns & Mac management team, and when we ask for something, we know it’s going to be done right. Our group has 100 percent confidence in Burns & Mac’s ability.”
The plant’s performance has been exemplary. In 20 years, the contaminant levels in the groundwater beneath the site have been knocked down significantly, while effluent samples taken from the plant outfall have always met required levels. “It also survived the Midwest floods of 1993, with only minimal downtime, despite the wells and surrounding property being submerged for 90 days,” Zanoni says. “The plant site is elevated to the 500-year flood level, and rising waters came within three feet of plant infrastructure. But aside from minor damage to fences, trees and monitoring wells, everything stayed in place.”
For more information, contact Pete Zanoni, 816-822-3241.
The Treatment System
Six major systems were initially incorporated in the FSRAC treatment plant:
- Equalization: Blends the flow from both withdrawal wells and aerates the water to convert iron compounds to the ferric form, while also removing at least half of the volatile organic compounds (VOCs).
- Hydroxide precipitation: Removes metals through several steps including pH adjustment, rapid mixing with polymer and slow mixing for floc formation, clarification, and further pH adjustment before flowing to biological treatment systems.
- Biological treatment: Reduces soluble organics and phenols via two fixed-film, packed towers with forced-draft aeration.
- Filtration: Removal of solids from the biotowers by a dual-media filter to protect the carbon adsorption columns.
- Carbon adsorption: Reduces the remaining concentration of organics to permitted levels.
- Sulfide precipitation: Uses soluble sulfide to reduce metal compounds in effluent. In 2003, this process proved to be unnecessary, and the EPA approved its removal.
The treated water is used for every plant water need except potable water and then held in a storage tank before metered discharge to the Missouri River. Effluent analysis has demonstrated since startup that the processes have successfully met the limits established for more than two decades, despite the complex mix of chemicals that must be treated.