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Project Details


Geosyntec’s regulator-approved phased approach to risk assessment and cost evaluation work at the LCP Holtrachem site resulted in a time- and cost-efficient evaluation.




Decommissioning and Demolition Plans and Mercury Containment Removal at a Former Chlor-alkali Manufacturing Plant

Project Objective
The LCP Holtrachem Site is a former chlor-alkali manufacturing facility which used the mercury cell process, located along the Cape Fear River near the coast of North Carolina. This ecologically sensitive area serves as a fishery, fisheries nursery area, and spawning area for the endangered short nosed sturgeon. Chlorine production lasted at the site from 1963 until 1999. In 2002, Honeywell entered into an Administrative Order on Consent (AOC) for a time-critical removal action of various mercury contaminated structures and wastes under the Engineering Evaluation and Cost Analysis (EE/CA) process. In addition to mercury, contaminants of concern at the site included lead, polycyclic aromatic hydrocarbons (PAHs), dioxins, and polychlorinated biphenyls (PCBs).

Geosyntec’s Scope of Services
Honeywell initially retained Geosyntec to assist in preparing decommissioning and demolition plans. Geosyntec then advised the client’s construction management team throughout the removal action on the mercury cell building and other mercury contaminated structures and wastes. Subsequently, in 2004, U.S. EPA issued another order for a non time critical removal action (an EE/CA) to address former waste disposal impoundments and contaminated environmental media on the facility and offsite along floodplains of the Cape Fear River (including sediments within the river). Geosyntec compiled all of the historic site characterization data records into a relational database and Geographic Information System (GIS) for the scoping of the EE/CA site characterization and ecological risk assessment, and; prepared the comprehensive, multi-media EE/CA project plans, including terrestrial and aquatic ecological risk assessment of the site and Cape Fear River. Early phases of site characterization and ecological risk assessment process (at Step 3 screening level risk assessment) quickly identify PCB as a primary human health and ecological risk driver for this site both within the site proper and in the offsite floodplain setting. Conditions within the Cape Fear River were demonstrated to be acceptable, and no further ecological investigation is required for this domain.

Notable Accomplishments
Geosyntec presented a novel approach to U.S. EPA for the ecological assessment for the floodplain whereby a projected human health-based cleanup would be modeled in terms of ecological risk reduction, with the strategy of opting out of the cumbersome (both time consuming and very costly) 8-step ecological risk assessment process at the preliminary screening level stage (Step 3). U.S. EPA and North Carolina Department of Environment and Natural Resources (NC DENR) concurred with this concept. Another element of the work involves the dredging of an offsite lagoon contaminated with PCB from site runoff, and the regulatory issues in the State associated with high-level PCB contaminated soil. Geosyntec is working with the regulators on the concept of an on-site Corrective Action Management Unit (CAMU) for the management of the high-PCB material. This solution would affect millions of dollars of cost avoidance over treatment and disposal options. Geosyntec obtained a variance of Land Disposal Restriction for the disposition of the removal-action wastes and debris, allowing for direct off-site disposal without the added cost of pre-treatment.

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