Selected Projects
Groundwater Assessment for the FMC Corporation
Jacksonville, Florida
Exponent provided technical support and consulting services to FMC at its pesticide formulating and repackaging plant in Jacksonville, Florida. The services provided at this site included an in-depth groundwater investigation, including the evaluation of natural attenuation of BHC, and a sulfur-isotope study to evaluate sources of elemental sulfur (and sulfate) in the groundwater aquifer; implementation of a groundwater monitoring program to evaluate the effects of the source removal (excavation) action; and a feasibility study for groundwater to evaluate groundwater treatment technologies to remove arsenic, pesticides, and volatile organic compounds from groundwater.
Exponent completed an in-depth groundwater investigation at this site, which included an evaluation of the potential for natural attenuation of BHC. This included an assessment of the mass of BHC lost over time, of the distribution of different isomeric forms of BHC, and the enantioselective degradation of alpha-BHC, to determine the extent to which the natural processes of adsorption, hydrolysis, and biodegradation were attenuating BHC migration. The results from this evaluation indicated that natural processes were effectively attenuating BHC in a large portion of the contaminant plume.
Exponent also conducted a feasibility study to determine the most efficient and cost-effective method for treatment of the groundwater contamination. The feasibility study included the development of a groundwater model to assess alternative treatment scenarios. It also included an evaluation of the implementability and economics of both in-situ and ex-situ groundwater treatment technologies, including a zero-valent iron wall, injection of nano-scale iron, air sparging, groundwater hydraulic control (pumping), and several physical and chemical ex-situ treatment technologies (e.g., activated carbon, activated alumina, and chemical precipitation). Given the complexity of the subsurface conditions, and the broad array of contaminants in groundwater, hydraulic control with ex-situ treatment was recommended as the remedy for this site.
EPA Risk Assessment Workgroups
As recognized experts in the field of ecological risk assessment, Exponent EcoSciences staff in the Boulder office have been invited to participate in national multi-stakeholder workgroups organized by the U.S. EPA on issues pertaining to ecological risk. These workgroups are working toward the development of ecological risk-based soil screening levels (EcoSSLs) and the development of an EPA framework for metals risk assessment.
St. Lawrence River Natural Resource Damage Assessment
Massena, New York
Exponent is providing technical support to Alcoa and General Motors during settlement negotiations in this nationally recognized NRDA involving sediments contaminated with PCBs and other substances from historical releases from industrial facilities to the St. Lawrence and Grasse rivers at Massena, New York. Active negotiations with state, federal, and tribal trustees have involved development and presentation of technical positions regarding threshold effects levels and concomitant injury levels for PCBs in sediment (benthic effects), birds, and fish. Technical positions are being developed in support of a streamlined cooperative process that focuses on achieving agreement on a settlement, rather than development of a quantitative NRDA.
Enhanced Natural Attenuation of Organic Solvents in Groundwater
International Paper Retail Packaging Facility
Wilmington, North Carolina
Exponent has developed a groundwater remediation plan based
on enhanced natural attenuation of organic solvents, which
will yield a net savings of up to $2 million compared to a
groundwater extraction and treatment system required under
the facility’s RCRA permit. To persuade state regulators
to adopt the revised plan and modify the permit, Exponent’s
environmental scientists and engineers used existing site
monitoring data to present a compelling technical case demonstrating
the effectiveness of natural attenuation for reducing chemical
concentrations, and developed a plan for enhancing these processes
using Oxygen Release Compound (ORC®). Exponent
also supported International Paper in developing regulatory
strategy, negotiating with agencies, preparing technical documents
and the RCRA permit modification application, and conducting
public meetings regarding the permit modification.
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