Church Creek Drainage Basin

Background

The Church Creek drainage basin drains a total of area of nearly 5,000 acres located along the western side of the Ashley River. Historically the area was composed mainly of old phosphate mines and marsh areas and today is approximately 80% developed with mainly residential and some commercial development. The present city limits consist of the residential neighborhoods of Shadowmoss, Hickory Hill, Hickory Farms, Grand Oaks, Village Green, Forest Lakes, and Canterbury Woods. The Church Creek drainage facilities consist of a natural drainage channel and marsh area located between the outlet under U.S. Highway 61 and the Seaboard Systems Railroad. Upstream of the Seaboard Systems Railroad portions of the existing channel have been improved between Bees Ferry Road and the railroad.

Significant development of the Church Creek drainage basin began in the early to mid-1970s. In 1986 townhomes constructed on Two Loch Drive flooded during a rain event. In response to this flood, Charleston County, SCDOT, and the City of Charleston combined efforts to increase the capacity of the basin's main outfall beneath the CSX railroad, adding three 72-inch culverts to the existing 66-inch culvert.

  • In the 1990s, new homes were constructed in the Still Shadow section of Shadowmoss. Throughout the 1990s these new homes were flooded during several rain events. After determining that the accepted engineering standards applied to stormwater system design were not effective in this drainage basin, the city approved a nine month building moratorium and initiated a detailed study of the drainage basin.
  • In 2001 the city, through its consultant, developed an ICPR model of the basin which was calibrated through comparison of know flood events. The study resulted in new design standards for new development in the basin and recommendations for system improvements that could lower flood levels.
  • In 2005, capacity was added to provide additional stormwater storage in conjunction with construction of the Middleboro section of Shadowmoss.
  • In 2007, the city completed a diversion project that intercepted a significant portion of stormwater runoff from the eastern side of Shadowmoss Plantation. The new system included a new canal and dual 4 by 8 feet box culverts which created a second outfall to Church Creek.
  • In 2010 the city constructed a 4 by 12 box culvert to add additional capacity from the Bridge Pointe pond to the main channel.

Updates

So far the city has spent $3,671,476 to construct improvements and monitor the effect of stormwater runoff from new development so that it does not adversely affect existing development. Determined to continue to alleviate the drainage challenges in this basin, the City of Charleston is continuing to update the existing ICPR model, review proposed development designs to ensure adherence to the strict stormwater design standards for the basin, maintain the existing collection and conveyance system, and seek out additional capital improvement projects to improve drainage.

Documents & Maps

Original 2001 Church Creek Drainage Basin Master Plan

Volume 1 Sections

Volume 2 Sections

Volume 2 Appendices

2015 Updated Data

Additional Documents