Environmental Project

Remedial Investigation, Risk Assessment, and Removal Action

Dominion Energy South Carolina, Inc. Columbia, SC

Solution Overview


Dominion Energy South Carolina, Inc.

Business Challenge:

  • Dense, non‑aqueous phase liquids (DNAPL)-impacted soil and debris at site managed under requirements of voluntary cleanup contract (VCC)


  • Prepared remedial investigation (RI) report and performed risk assessment to develop remedial action objectives (RAOs) for removal of manufactured gas plant (MGP)‑impacted material


  • Following successful interim removal action (IRA), Apex Companies developed and implemented an effectiveness monitoring plan (EMP) to determine post‑remediation groundwater quality and subsequent occurrence of natural attenuation


The client (formerly SCANA Services, Inc. which was acquired by Dominion Energy and became Dominion Energy South Carolina, Inc.) hired Apex to develop a RI and perform risk assessment for the site of a former MGP—located in a busy downtown—in which much of the subsurface was found to contain DNAPL‑impacted soil and debris. The Apex team worked under the guidelines of the responsible party VCC and the state agency (South Carolina Department of Health and Environmental Control) administratively managing the site.


Apex’s remedial investigation was used to develop RAOs for an IRA. Working closely with the client in a collaborative effort, Apex recommended removal of the MGP-impacted material as the preferred approach for the IRA.

Apex developed project specifications and provided procurement and onsite management support, oversight of the remediation contractor, and project documentation.

The multi-year removal action included:

  • Demolition of existing site structures

  • Removal of approximately 125K tons of impacted material

  • Excavations that ranged in depth from 2 to 29 feet below ground surface

  • Removal and replacement of approximately 270 linear feet of a 6-foot diameter concrete storm drain

  • Site restoration and placement of a stone surface cover


Following the successful completion of the IRA, Apex developed and is currently implementing an EMP to determine post-remediation groundwater quality and the subsequent occurrence of natural attenuation. Our team has also assisted the owner with potential opportunities for divestiture of the property.

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