Dec 12, 2016

Webb Bridge Park Water Quality Improvements

Lake Windward, the largest lake in Alpharetta, Ga., was a financial liability for the city. It required constant upkeep and regular dredging to remove sediment, which was negatively impacting the environment and recreational use of a private lake.

Following an inquiry from the lake owner, the city established a team to study the area. The team conducted field assessments, measured water quality and performed hydrologic and hydraulic analyses. The city ultimately restored 350 ln ft of a local stream, installed three bioretention ponds, updated three parking lots and repaired aging storm water infrastructure.

“The success of these projects has shown that it is not as difficult to retrofit water quality measures into dated infrastructure as once thought,” said Pam Bush, civil engineer for the city.

While attractive to the eye, the in-stream features and grading provided several management functions. Both sides of the stream reach incorporated a bankfull bench and the banks were tied back into the existing grade at a 2-to-1 slope. Rock J-hooks, step pools and riffles were constructed, and a geo-lift structure stabilized the banks while re-establishing vegetation.

Community involvement became an important facet of the project.

“[Residents] are fully invested in their local government and the future of the city,” said Jill Bazinet, senior storm water engineer for the city. “The surrounding residents have always been involved in the park, but the environmental concerns downstream at Lake Windward helped prioritize this project.”

Those living downstream from the project have noted improvements on their properties, particularly a reduction in erosion. The project’s success extended beyond its practical use.

“Because of the park’s location, it is an ideal spot for school children to learn about water quality sampling and protection of our natural resources,” said Terry Porter, environmental programs coordinator for the city of Alpharetta.

Project Year:
Contractor: River Works Inc., Blount Construction Co. Inc., Tri Scapes Inc.
Designers: Manhard, Woolpert
Owner: City of Alpharetta
Location: Alpharetta, Ga.
Cost: $900,000
Size: 95-acre park, 350 ln ft of stream restoration, 1.3 acres of bioretention