2013 Sewer Spill Summary

Sewer spills, also referred to as sanitary sewer overflows or SSOs occur when raw sewage is discharged from a sewer collection system and are one of the top water quality concerns in the Midlands.  SSOs, because they contain raw sewage, can result in serious public health concerns as well as ecological damage to streams and rivers.


Sewer Spills on the Lower Saluda River

According to DHEC records obtained through a Freedom of Information request there were more than 200 SSOs in the Broad, Lower Saluda and Congaree watersheds in 2013 resulting in a total volume of more than 1.8 million gallons spilled.  It is important to note that most entities are only required to report a spill to DHEC if it is more than 500 gallons or if it enters a waterbody.  The City of Columbia is a notable exception, as they are required to report all of their SSOs.  The chart below provides a summary of the number of spills and volumes for each of the 18 sewer systems that reported a spill.

As can be seen in the chart, the City of Columbia is responsible for more than half of the volume of all SSOs in the region.  With approximately 1,200 miles of pipe Columbia operates the largest sewer collection system in the region, larger than the next three systems combined.  The City also recently entered into a consent agreement with DHEC, the EPA and the Department of Justice to address their ongoing sewer spills.

The 10 largest spills in our area are responsible for approximately 75% of the total volume of SSOs.  The details, including location, affected waterbody, and cause, for all SSOs 10,000 gallons and greater are listed in the chart linked here: SSOs over 10,000 Gallons Chart.

Analysis showed that three specific areas account for more then half of the volume of all the SSOs.  Those areas are Gills Creek/Mill Creek, the Saluda River basin and Crane Creek (a tributary to the Broad River).

A majority of the SSOs, by volume, were caused by malfunctions at treatment plants, construction related activities, and human error.  Another significant cause of SSOs was inflow and infiltration.  Inflow and infiltration occurs during precipitation and high water events when rain or floodwater enters the sewer system through failing infrastructure like broken pipes and missing manholes.  Inflow and Infiltration is responsible for most of the SSOs on Crane Creek as well as many other areas.

As alarming as 2013's SSO numbers are, 2014 is already off to a worse start.  So far this year there have been 33 spills totaling over 600,000 gallons.  A number of these spills were related to a rain and high water around January 11th, including one spill by the City of Columbia of about 420,000 gallons on Crane Creek.  

You can view a list of all recent SSOs across the state on DHEC's website hereā€¦http://www.scdhec.gov/HomeAndEnvironment/Pollution/DHECPollutionMonitoringServices/WastewaterOverflows/