In June 2010, DHEC responded to a report of tar-like material (TLM) in the sediments of the Congaree River. The affected area begins directly south of the Gervais Street Bridge, extending approximately 200-300 feet into the river from the eastern shoreline, and approximately 2,000 feet south downriver towards the Blossom Street Bridge. At that time, DHEC began an investigation that included collecting surface water and sediment samples. DHEC also posted metal signs warning against swimming or wading in the area as a precautionary measure.
Preliminary sample results indicated that the TLM had similar chemical and physical characteristics as coal tar, a by-product of Manufactured Gas Operations which were common in cities from the late 1800s until the 1950s. Additional research found that the most likely source of the TLM was a former Manufactured Gas Plant (MGP) located northeast of the river at 1409 Huger Street that operated from about 1906 until the mid-1950s. Later this was the location of the city bus terminal until 2008.
MGPs produced a flammable gas from coal that was used for heating, cooking and lighting purposes prior to the construction of interstate natural gas pipelines. The coal tar material was a waste product from coal-gas production. Once the gas was produced, the coal tar by-product was discharged into a former stream which originated at what we know today as Finley Park, past the MGP site, and into the Congaree River just below the Gervais Street Bridge. The Huger Street MGP was operated by predecessor companies of South Carolina Electric & Gas (SCE&G) beginning in the early 1900s and ending in the 1950s, prior to the existence of environmental regulations and permitting.
SCE&G had previously entered into a Voluntary Cleanup Contract (VCC) with DHEC in August 2002 to conduct environmental assessment and cleanup activities at the former Huger Street MGP site. SCE&G has worked proactively and cooperatively with DHEC under its existing VCC to determine the extent of TLM in the Congaree River and to develop a plan for cleanup.