U.S. Environmental Protection Agency (EPA) continues its cleanup effort at the Standard Chlorine of Delaware Superfund Site, also known as the Metachem Site, located in New Castle County, Delaware. EPA has been cleaning up the site in four separate parts called "operable units" or OUs. The EPA has announced a proposed Record of Decision (ROD) Amendment for addressing off-site contaminated soils at the site. These off-site soils are referred to as Operable Unit 2 (OU-2). EPA held a public meeting in Delaware City to discuss the OU-2 Proposed ROD Amendment on Jan. 12, 2016. The EPA OU-2 Proposed Plan for the ROD Amendment is available here.
EPA working to stop infiltration: In spring 2015, EPA restored areas of the soil bentonite containment barrier wall, or "barrier wall" that have shown signs of infiltration from groundwater outside of the contaminated groundwater plume. The barrier wall is a subsurface, vertical barrier around the site that helps keep the contaminated groundwater plume from migrating off-site and allows the pump-and-treat system to work efficiently. It is also sometimes called a "slurry wall." The barrier wall has been highly effective by containing contaminated groundwater inside of it that enables more effective and efficient treatment. During cleanup operations, EPA detected groundwater entering the barrier wall. The water entering the confined area does not contain site contaminants. It is, however, adding to the volume of water that is being treated, which affects the treatment system’s efficiency. EPA will repair the section of the barrier wall in the southwest corner of the site where infiltration has been detected this spring. For more information, please see the EPA's fact sheet.
In 2013, the US EPA-National Renewable Energy Laboratory (NREL) Solar Feasibility Study for the former Metachem (a/k/a Standard Chlorine of Delaware) Superfund Site was completed and is available here. WHS’ Site Investigation & Restoration Section (SIRS) submitted an application to the US EPA in 2011 for a grant to fund the feasibility study. NREL provided technical assistance for the project. The purpose of the study was to assess the site for a possible photovoltaic (PV) system installation and estimate the cost, performance, and site impacts of different PV options. The study also reviewed financing options that could assist in the implementation of a PV system at the site. For more information, please visit the USEPA’s RE-Powering Feasibility Studies webpage.
Photo: An excavator arm capable of achieving 90-foot depth works on preparing a slurry wall that acts as a groundwater remedy at the Metachem site near Delaware City. Photo by Todd Keyser
Metachem Products, LLC and its predecessor, Standard Chlorine of Delaware, both manufactured chlorinated benzene chemicals at an 85-acre site near Delaware City for more than 35 years. The facility operated as Standard Chlorine from 1966 to late 1998 when it was purchased by Connecticut-based Charter Oak Capital Partners and renamed Metachem.
Throughout its operation, and particularly in the 1990s, Standard Chlorine had a history of chronic non-compliance with numerous environmental laws. The site was listed on the US Environmental Protection Agency's Superfund National Priorities List (NPL), having been cited because of numerous tank-related spills and soil and groundwater contamination in the 1980s.
Standard Chlorine’s legacy of non-compliance was transferred to the new owners who eventually negotiated a Consent Decree with the State of Delaware in 2001 providing for compliance and site cleanup. However, poor market conditions in the chlorinated benzene business caused the company to declare bankruptcy in May 2002, and Metachem abruptly closed and abandoned the plant. With no environmental cleanup funds set aside by the company, or its owners Charter Oak Capital, the cost of removing accumulated hazardous product and waste was left to the state of Delaware and the U.S. Environmental Protection Agency (USEPA).
In an effort to remove feedstock chemicals that otherwise would have become hazardous waste, the USEPA resumed limited operation of the plant. With state oversight of the USEPA's Removal and Remedial Programs, chemicals were solidified and stabilized for feedstock, and as needed, for disposal, thereby reducing the potential for further environmental problems and accompanying costs. Today, what comprised the chemical portion of the plant – which previously encompassed buildings, process vessels and piping, and a wastewater treatment plant – has been properly decommissioned and is being dismantled, with state support from DNREC's Division of Air and Waste Management. The Division's Site Investigation and Restoration Branch (DNREC-SIRB) was part of the coordination of multiple contractors tasked with demolition, asbestos abatement, and contaminated material removal for incineration. SIRB also ensured that the contractors were provided with an active water supply for remediation, construction and fire safety.
In 2008, construction was completed for groundwater remediation at the site, including a subsurface concrete barrier wall around the site and a system to pump and treat the contaminated groundwater inside the wall. The concrete slurry wall that encircles the site, along with the pump and treat system, is a complex groundwater remediation system with multiple extraction wells. The system is designed to treat the groundwater to drinking water standards before discharging the water to the Red Lion Creek. The slurry wall "keys into" a basal clay layer up to 70 feet beneath the surface and creates a “bathtub” that contains the majority of the contaminated groundwater at the site.
Implementation of this interim groundwater remedy was a combined effort of oversight by USEPA Region 3 and DNREC-SIRB. The USEPA hired a environmental consultant to implement the construction of the slurry wall and treatment system. DNREC-SIRB has been part of the update and progress meetings, as well as the decision-making process for implementation. In addition, SIRB worked with the Division's Tank Management Branch on an unanticipated underground storage tank removal of tanks that were in the line of the slurry wall as it progressed along the southern edge of the site. Removal of the previously closed tanks was not part of the original scope of work, but was undertaken when wall was realigned to enable a more stable work platform for the excavator.
The groundwater treatment system has been active for several months. However, the groundwater remedy is a long-term solution with an as-yet-to-be determined timeframe – possibly ongoing over decades. Other remedial tasks also are ongoing at the site, including chemical disposal, and a soil and wetlands contaminant investigation. A specific remedy has not been selected for the soils or the wetlands; however, several innovative treatment methods are being evaluated that are less costly and more efficient. DNREC-SIRB will have a consequential role in this decision-making process as it progresses.
For more information, please contact Todd Keyser, the DNREC-SIRB Project Manager, at 391 Lukens Drive, New Castle, Delaware 19720; phone: (302) 395-2600, fax: (302) 395-2601; or e-mail: Todd.Keyser@state.de.us. Additional site information can be found at the following websites: