Nashville Zoo Croft Pond: Silt Stop and Floc Logs Restore a Habitat Under Foot Traffic

Croft Pond is one of the first habitats visitors see at Nashville Zoo—roughly 90′ 260′ (about 23,400 ft) and home to waterfowl including Black Neck Swans. Historically the pond struggled with low summer flow, leaks, a contaminated spring, and industrial-park stormwater. After failed dam-seal attempts, a mild storm in March 2005 drained the lake completely. Before repairs, about 7,000 tons of sediment under three feet of water had to come outbut limited walkway access ruled out large excavators, and even a small trackhoe was unsafe on muskrat-riddled banks and cracked concrete.

Consultant Gary Moody (Jen-Hill) sent soil and water samples to APS for a site-specific match, then deployed 250 pounds of APS 705 & 712 Silt Stop powders with eight APS 703d Floc Logs. Upstream flow was pumped back into a wetland for a zero-flow work zone. Each morning, clean water discharged over Floc Logs into a gabion detention area; Floc Logs also treated the spring-fed stream and stormwater ditch. After about two hours of dewatering, crews removed sediment that had been isolated and stabilized with Silt Stop the afternoon before—sometimes mixing powder into the water and soils with a submerged pump nozzle until the muck solidified for scooping into single-axle trucks.

The project cost over $130,000 and finished in 28 days while the zoo remained open. After sediment removal, an island was built for birds; the dam was repaired with GSE Polylock and a geomembrane to stop further draining and off-site contamination. Native riparian plants, special grasses, and wetland sod completed the exhibit. Croft Pond reopened on time and on budget as the Black Neck Swan habitatwork that conventional methods could not have done under the zoos access and operations constraints.