On February 4, 2019, DHEC approved SCE&G (now Dominion Energy) to move forward with the permitting process for a Modified Removal Action (MRA) to address tar-like material (TLM) in the Congaree River. This MRA was derived from meetings between SCE&G, DHEC, and primary stakeholders to target areas for removal where TLM is at its thickest and has the greatest potential for human exposure. This MRA acknowledges that some TLM might remain in the riverbed but situated in areas that would pose very little future risk to human exposure.
The proposed MRA consists of two areas. Area 1 is approximately 2.6 acres and has a similar footprint to the original full-scale Phase 1 area. Area 2 is approximately 0.5 acres in size. Assuming successful completion of the MRA as proposed, an estimated 73% of the total TLM is expected to be removed from the Congaree River.
Regulatory permits and approvals will be required from the USACE, various sections within DHEC, the SC Department of Natural Resources, the Federal Emergency Management Agency local floodplain coordinators, the City of Columbia, and other related state and local authorities to conduct the proposed work within and adjacent to the Congaree River.
The figure below provides a visual representation of the areas targeted for a modified removal action and their location.
Figure 3 provides an updated depiction of the average TLM thickness with estimated volume, using a similar GIS tool in which the TLM representation extends into the adjacent data point.