The site-wide remedy (designated by the U.S. Environmental Protection Agency as OU4) addresses impacted soils, groundwater, and impoundments that have not been previously addressed, with the exception of Impoundments 1 and 2 (OU8).
On December 8, 2015, a formal agreement (i.e. Consent Decree) between the United States, on behalf of the U.S. Environmental Protection Agency (USEPA), and Wyeth Holdings LLC (WH) was signed authorizing WH to move forward with implementation of the site-wide remedy as described in the Record of Decision issued by USEPA on September 27, 2012.
Construction of the bedrock and overburden groundwater containment, extraction, treatment, and reinjection system, a major component of the site-wide remedy, is complete and the system is fully operational.
Pre-design and design activities related to the site-wide soils remedy, including design of the stabilization/solidification treatment process for waste materials located in Impoundments 3, 4 and 5, will occur in 2023.
Site-wide Remedy Components
The site-wide remedy, as described in USEPA’s Record of Decision, will provide long-term protection to human health and the environment and will return the property to beneficial use. The major components of the remedy are listed below:
- The existing bedrock groundwater collection system has been improved by modifying the primary extraction wells and by adding several new extraction wells to ensure that all site-related groundwater is captured. In addition, an overburden groundwater collection system and containment walls were constructed. The groundwater collected at the site is now treated on-site and reinjected to bedrock groundwater following treatment.
- An ecological risk assessment was performed for three impoundments located in the flood plain. Based on the results of the ecological risk assessment, impacted areas identified within the top two feet of the impoundment caps and found to be an exposure risk may be relocated and consolidated in the North Area under the appropriate engineering controls.
- Waste material located within Impoundments 3, 4, and 5 will be treated entirely in place through stabilization and solidification technologies to prevent migration. This treatment method is a proven technology that immobilizes contaminants. Following solidification, an impermeable engineered vapor control barrier will be installed.
- For site-wide soils that exhibit similar characteristics as identified within Impoundment 3, 4, and 5, complete excavation and relocation to Impoundments 3, 4, and 5 will be required along with the same treatment methods mentioned above.
- For site-wide soils determined to require a vapor control barrier, which also includes a vapor mitigation system, an impermeable multi-layered engineered cap will be constructed. These soils typically contain volatile and semi-volatile organic compounds that have the potential to migrate into the atmosphere.
- For site-wide soils determined to require a direct contact barrier, an engineered soil cover will be utilized. Soils requiring this engineered cover typically consist of low-level contaminated media above the soil remediation standards outlined in the USEPA Remedy decision document.