Formatted Title:

Use of Multiple Lines of Evidence to Assess Risk, Develop Remedial Alternatives, and Select a Preferred Remedy for the Lower Genesee River

Background/Objectives:

The Lower Genesee River (LGR) in Rochester, New York, has been the focus of a RCRA Facility Investigation (RFI) and a Corrective Measures Study (CMS) conducted on behalf of the New York State Department of Environmental Conservation’s (NYSDEC’s) Division of Environmental Remediation. Silver was determined to be the primary contaminant of concern in river and wetland sediments from Kodak’s film-making operations at its former Kodak Park facility. Remedial alternatives were evaluated for their ability to reduce potential impacts to the environment from silver. The selected alternative was finalized in 2020, and remedial construction was largely completed in 2021 with minor restoration tasks completed in 2022. Procurement of federal, state, and local permits began in 2019, with final permits secured in 2021 prior to the start of construction.

Approach/Activities:

The RFI was conducted to develop an understanding of the nature and extent of contamination in the LGR and to determine whether corrective actions to prevent impacts to human health or the environment were warranted. RFI tasks included multi-media sampling and chemical analyses, geochronology cores for radioisotope analysis, physical characterizations and hydrodynamic modeling of the river channel, assessments of sediment toxicity and bed mobility, and a fish and wildlife resource impact analysis. Based on results of these activities, the RFI concluded that no human health impacts were anticipated under the passive recreational use standard. However, a robust ecological community was identified with potential impacts in mussels and forage fish exposed to high concentrations of silver in localized areas of the site. Therefore, a toxicity-based action level of 70 mg/kg was developed to screen potential ecological risk impacts due to silver contamination of river and wetland sediments at observed concentrations.

The CMS was then performed to evaluate corrective measure alternatives for river and wetland sediments and to determine which remedial technologies were best suited for remediation of the LGR. Multiple lines of evidence were used to evaluate each alternative’s ability to meet the overall goals of preventing exposure to ecological receptors and preventing transport of impacted sediments to areas of the river with little or no impacts. Lines of evidence included ecological assessments, scour potential, and site-specific sediment toxicity.

Results/Lessons Learned:

Based on the multiple lines of evidence evaluated, the remedial action objective focused on remediation of areas with the potential for transport of contaminated sediments exceeding the toxicity-based action level for silver. The final remedy consisted of dredging followed by placement of an isolation cap in two areas of the river that exhibited high scour potential and silver concentrations above the site-specific action level of 70 mg/kg. In a portion of one of these areas, a cap only approach was implemented to mitigate adverse structural impacts to an adjacent wastewater treatment plant (WWTP) and infrastructure associated with the WWTP. The remedy also included excavation and backfill in a wetland area where silver concentrations exceeded the toxicity-based action level. Restoration was accomplished through wetland plantings and natural channel restoration methodologies. Restoration monitoring is ongoing and additional enhancements to the planting may be required in the emerging wetland areas due to elevated river levels after the initial planting was completed.

Kristen Brooks

Affiliation

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Use of Multiple Lines of Evidence to Assess Risk, Develop Remedial Alternatives, and Select a Preferred Remedy for the Lower Genesee River