X-740 Plume Excavation

Work is underway at Portsmouth on the first
of five legacy groundwater plumes which will
be excavated to obtain soil for use in the newly constructed On Site Waste Disposal Facility (OSWDF) as engineered fill during demolition debris placement. The 5M cubic yard OSWDF requires a 2.4:1 ratio of fill material to waste. Using soil from legacy groundwater plumes and old landfills on site avoids buying clean fill for the OSWDF, expedites the environmental cleanup of the site and provides more land for future reuse.

Since the 1990’s plume contaminants, mainly industrial solvent trichloroethylene (TCE) used during the plant operations, have been extracted from the ground with traditional groundwater pump-and-treat operations. However, it’s a slow process that can be costly over time. By digging up the remaining contaminant sources and contaminated soils, the cleanup of the groundwater plumes is significantly accelerated. Removal and consolidation of legacy environmental concerns including groundwater plumes and old landfills also makes more land available for future community reuse /

reindustrialization – a benefit for stakeholders
who want to build a sustainable economic future
at the site post-cleanup. DOE has already begun
the process of transferring clean parcels of land to
the designated Community Reuse Organization,
the Southern Ohio Diversification Initiative (SODI).
The first parcel, 80 acres, was transferred to SODI
in 2018 and another 220 acres is scheduled to be
transferred this year.

The work is performed with regulatory approval
under a Natural Resources Damage Act settlement
and DFF&O (Director’s Final Finding and Order)
authorizing excavation of five existing groundwater
plumes as well as five closed waste units (e.g.,
landfills). Each individual waste unit or plume

Aerial view looking east at the X-740 as operations continue blending and loading impacted soil for placement at the PORTS On-Site Waste Disposal Facility.
Aerial view looking east at the X-740 as operations continue blending and loading impacted soil for placement at the PORTS On-Site Waste Disposal Facility.

then needs an approved Excavation Work Plan
before excavation can be initiated - ensuring that
excavation can be done safely, protectively, and
compliant with all ARARs (Applicable or Relevant
and Appropriate Requirements). The excavated
materials will then be used as engineered fill in
the OSWDF according to the approved Waste
Acceptance Criteria.

X-231B and X-231A Landfills will be excavated
in the next two years to place X-326 debris in the
OSWDF.