Summary

This 100 acre former wood treating site is located in Nashua NH along the Merrimack River. The site is being addressed via a consent decree between the owner and the New Hampshire Department of Environmental Services. The past history of pressure treating of various wood products, such as rail ties and utility poles with creosote, have resulted in the presence of Dense Non Aqueous Phase Liquids (DNAPL) in the subsurface. KEY and its affiliate FTS have been involved in the investigation and remediation of the site. Remediation challenges at the site were further complicated by varied geologic conditions, bordering along a navigable river used for recreation, and being adjacent to a city owned park. Remediation planning took into consideration redevelopment of the site.

Techniques

Investigation:

Tar Specific Green Optical Screening Tool (TarGOST)

Extensive terrace deposit and bedrock investigations soil and groundwater investigations

River sediment investigations

Environmental Visualization Software (EVS )

DNAPL recover evaluations

Permitting:

NHDES- wetlands, shoreland, alteration of terrain and groundwater injection

USACOE – Wetland

City

Community relations

Remediation:

Well abandonment

DNAPL Recovery

Cement bentonite barrier wall

River sediment excavation

River restoration using reactive core mat and capillary break

In-situ chemical stabilization

On-site consolidation and capping of impacted soils

Air monitoring

Operation and Maintenance (FTS)

Daily operation of remediation components

Triannual groundwater monitoring and reporting

Waste management