Aquifer Protection and Dynamic Engineering-Water Quality Pond Rehabilitation Project

Challenges

TRC assisted a client with characterization and removal of accumulated sediments in a Water Quality Pond in the Edwards Aquifer Recharge Zone and the sensitive Barton Creek Watershed. The pond served a major highway intersection and had to remain in service while TRC performed the work. Therefore, samples had to be collected through standing water, making collection of representative samples difficult. Standing water, access restrictions and continued operation of the pond during removal required careful planning and close attention to weather events.

Solutions

TRC was able to safely collect representative samples through shallow standing water. Where deeper water was encountered, a dredge sampler was used to collect sediment samples. Construction proceeded only after TRC biologists determined that there were no sensitive species or habitats in the pond or nearby. With the representative sample information and knowledge of the sediment source, TRC was able to negotiate more reasonable disposal rates that allowed the project to proceed. TRC developed a staged construction approach that allowed operation of the pond to continue while sediments were removed. Standing water was pumped from the pond through filter bags to avoid negatively impacting the receiving stream or the karstic Edwards Aquifer Recharge features located there. Finally, loading and transportation operations were adjusted to minimize disruptions to local businesses.

Results

The water quality pond is critical to maintaining sensitive environmental features of the Edwards Aquifer Recharge Zone and to the Barton Creek watershed. TRC was able to facilitate timely and cost-effective rehabilitation of the pond without taking it out of service. The rehabilitation project restored the effectiveness and functionality of the pond in removing sediment and debris from stormwater prior to discharge thus protecting critical features and habitats.