EPA Enforcement Action to Protect Creek in Columbia, Mo.

A developer and a contractor will plant native trees, shrubs and grasses along the northern bank of Hinkson Creek in Columbia, Mo., and will pay a penalty of $146,833 for environmental harm they caused to the stream and a tributary.

The U.S. Environmental Protection Agency today announced the settlement of Clean Water Act violations with the developers of the Wal-Mart Supercenter and shopping center on Grindstone Parkway in Columbia.

The administrative penalty against THF Grindstone Development LLC and contractor Emery Sapp & Sons Inc., both of Columbia, is one of the largest for construction-related violations of the Clean Water Act ever imposed by EPA Region 7, which includes Missouri, Iowa, Kansas, and Nebraska. The penalties were imposed for illegal discharges of sediment, earth, and concrete into an unnamed tributary of Hinkson Creek.

EPA determined that the construction site lacked proper erosion controls, leading to runoff of sediment into the Hinkson Creek tributary in violation of the state discharge permit and federal stormwater requirements.

The U.S. Army Corps of Engineers notified EPA that there were concrete culverts built directly onto the banks and into the Hinkson Creek tributary without a permit required by the Clean Water Act.

The illegal culverts, which increased the speed of the stream, made erosion and sediment shifting problems worse.

EPA determined that the construction activities conducted by THF and Emery Sapp worsened environmental conditions in Hinkson Creek, which already had been classified by Missouri as impaired. Hinkson Creek was historically popular for its many recreational uses, but increased agricultural and urban runoff during the last decade caused the water quality of Hinkson Creek to deteriorate as the stream bank eroded.

The settlement agreement requires THF and Emery Sapp to prevent further erosion by restoring two acres of the Hinkson Creek stream bank near Scott Boulevard with plantings estimated to cost $70,000.