Site Investigation and Remediation Case Study:
Hydrogeologic Evaluation and Development of Groundwater Monitoring Plan

CASE: Hydrogeologic Evaluation & Development of Groundwater Monitoring Plan

LOCATION: Westchester County Airport, NY

OBJECTIVE: Determine if groundwater beneath Airport impacts nearby Rye Lake
STRATEGY:

First Environment’s task was to determine if groundwater beneath the Westchester County Airport (the Airport) flows toward Rye Lake and, if so, to develop a sampling plan to determine if the groundwater had been impacted by Airport activities. This project was initiated voluntarily as a matter of good environmental policy rather than because of any legal obligation.

The mission assigned to First Environment was threefold. First, to complete a hydrogeologic evaluation of the Airport to develop a conceptual understanding of groundwater flow patterns and recharge areas. Second, to conduct a detailed evaluation of the Airport property to identify all possible activities and associated contaminant sources, and to investigate each possible source individually to determine its effect, if any, upon the surrounding environment. Third, to devise a monitoring plan that will ensure the County’s ability to systematically evaluate and react to any potential groundwater contamination threat from the Airport to the waters of Rye Lake and the surrounding environment.

As a result of the first task, we determined that a relatively small portion of the groundwater flow beneath the surface of the Airport moves toward Rye Lake. For the second task, documents related to Airport operations and incidents were reviewed. Data gaps were identified and recommendations were made to close these gaps, either by virtue of additional documentation or intrusive investigation.

Using the information garnered, First Environment developed a Draft Groundwater Flow Evaluation and Sampling Plan Report (Draft Report). The Draft Report discussed the hydrogeologic findings and presented an area-by-area discussion of both present and past on-site activities. Recommendations were made for additional investigation, as appropriate. Copies of the Draft Report were distributed to the regulatory community and the community at large. Open meetings were held to discuss the findings of the report, the iterative nature of the process, the ultimate goal and to address concerns of the public. Written comments were received on behalf of the community at large, the New York State Department of Environmental Conservation (NYSDEC), the New York City Department of Environmental Protection (NYCDEP) and technical recommendations were provided by the New York State Attorney General’s office.

The Airport prepared an Investigation Work Plan, which responded directly to the issues raised in the State Attorney General’s technical recommendations. The additional investigation/remediation activities described in the Work Plan are ongoing and are designed to develop a complete set of data necessary to confirm that the operations at the Airport are not adversely impacting the Rye Lake or the surrounding environment and to design and develop a monitoring plan that will ensure the County’s ability to systematically evaluate and react to any potential groundwater contamination threat from the Airport to the waters of Rye Lake and the surrounding environment.