On March 21, 2013, DHEC held a public meeting to discuss the Engineering Evaluation/Cost Analysis (EE/CA) and present Alternative 4 — Removal of the TLM and Impacted Sediments, as the preferred remedy for cleanup of the Congaree River sediments. All of the comments received during the public comment period were in favor of Alternative 4.
In October 2013, SCE&G began the design and permitting process for construction of a cofferdam to allow for excavation of sediments and tar-like material (TLM) in the Congaree River under dry conditions. From 2013 through the first half of 2015 meetings were held between numerous state and federal stakeholders - including DHEC, SCE&G, and the US Army Corps of Engineers (USACOE), in pursuit of the cofferdam design. During the permitting process, several significant design issues with the cofferdam were identified and caused the need for a re-evaluation of the proposed removal action. These issues included:
In July 2015, SCE&G submitted a Work Plan proposing to try an alternate removal approach of building a temporary dam using large sandbags to allow for excavation in the river. DHEC and the USACOE agreed to allow SCE&G to conduct a pilot test to see if this alternative could work. SCE&G began the pilot test on September 29, 2015. However, on October 4, 2015, historic flooding washed out the old canal upstream of the removal area and deposited up to 5 feet of sediment over some of the areas to be excavated.
On July 12, 2016, SCE&G submitted a Field Demonstration Project Documentation Report on the pilot test to DHEC. The report concluded that the sandbag approach would not work. SCE&G requested that DHEC reconsider allowing capping of the area due to current river conditions and the negative effects of the proposed cofferdam.
On August 16, 2016, after careful evaluation of all the previously considered alternatives, DHEC sent a letter requesting SCANA to evaluate if Alternative 3 -Sediment Capping and Institutional Controls would meet the USACOE permitting requirements. The purpose of this was to determine if the USACOE permit requirements could be met for the capping alternative, as they could not be met for the removal alternative.
On September 22, 2016, SCE&G submitted the Joint Federal and State Application to the USACOE for review of the capping alternative. This application is currently under review by the USACOE. Pending a decision by the USACOE, DHEC will pursue finalizing a cleanup alternative. Additional opportunities for public engagement will be provided by DHEC prior to selection of a final cleanup action.