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Torrence Creek BMP Project

Water Quality Improvement

The North Mecklenburg Recycling Center offers the best of both worlds: recycling for the public and cleaner storm water runoff.

Three large rain gardens built by Storm Water Services now catch 100% of the storm water that flows off the five-acre Recycling Center site in Huntersville. Rain gardens are BMPs or "Best Management Practices."

This picture tells the story. "Before" shows a sample of storm water runoff as it enters a rain garden at the Recycling Center.

"After" shows that same water after it was filtered by grassy rain gardens at the Recycling Center. 
     Before and after samples of storm water runoff

Compared with runoff from other commercial sites, storm water at the Recycling Center in Huntersville tends to have higher concentrations of metals, bits of dirt and debris, and fertilizers. That runoff used to go to Torrence Creek, part of the McDowell Watershed. That watershed empties into the lake that supplies Charlotte-Mecklenburg's drinking water.

But now, the storm water runoff is directed to one of the BMPs where many of the pollutants are filtered out naturally.

Rain garden filled with storm water
Rain gardens slow the flow of storm water
and remove many contaminants

The BMPs temporarily hold the water, allowing contaminants to filter through the grass and specially-formulated soils.

By slowing the flow of the runoff, the rain gardens also reduce bank erosion in Torrence Creek and may reduce some risk of localized flooding. 
 
Monitoring has now begun. Storm Water Services is collecting data to observe how much pollution is being removed from the runoff. The data also compares the effectiveness of the types of plants and types of soils in the rain gardens.


Objectives:

  • Build rain gardens to treat 100% of storm water running off the property
  • Improve storm water quality and decrease amount of storm water runoff after typical rain events
  • Monitor performance of new techniques regarding design and function of rain gardens 
 This September 2010 mailer shows how this project is making a big difference in water quality.
 
 

Sign at North Mecklenburg Recycling Center property

Construction completed: November 2009 
Water quality monitoring: Began 2010
Construction Cost: $307,000
(Design, construction, landscaping)

Sources of Funding:
Charlotte-Mecklenburg Storm Water Services--$148,000
Mecklenburg County Solid Waste Services--$14,000
NC Clean Water Management Trust Fund--$145,000

Project Manager:
David Woodie
Charlotte-Mecklenburg Storm Water Services
704-336-3873