Govalle Wastewater Treatment Plant Flow Diversion

Austin, Texas

The project consisted of the diversion of flow around the existing diversion structure located at the old Govalle Wastewater Treatment Plant (WWTP) north of the Colorado River and the decommissioning of the SAR Transfer Station (an old existing lift station) south of the Colorado River. The Linger Lane Lift Station portion of the project (north of the Colorado River) was a great engineering project as it involved several old existing lines that drain into the existing diversion structure at the Govalle WWTP. The diversion structure accepts flow from a 36-inch gravity line, a 48-inch gravity line, and a 36-inch force main from Boggy Creek Lift Station. The diversion structure basically equalizes the flow, surcharging the system, until there is enough head to push the flow through the siphons under the river. However, the surcharging is causing the system to back up for miles upstream into East Austin.

The new lift station was designed to capture and divert the flow from the 36- and 48-inch gravity lines. Meanwhile, the 36-inch force main from Boggy was rerouted around the diversion structure. Altogether, the new lift station and rerouting of the 36-inch force main from Boggy Creek Lift Station allowed the diversion structure to be removed. As an alternative, a 30-inch gravity line was constructed to divert the flow from the 36- and 48-inch gravity lines instead of the lift station. The 30-inch gravity line would extend from the Govalle WWTP to the Boggy Creek Lift Station 1 mile away. Meanwhile, a new 36-inch force main was designed to go from the Govalle WWTP site, under the Colorado River, bypass the SAR Transfer Station on the south side of the river, proceed east along Hergotz Lane, and empty into an existing gravity manhole 500-feet east of the SAR Transfer Station. The new 36-inch force main was designed utilizing state-of-the-art horizontal directional drilling methods so that it can be tunneled under the Colorado River such that the existing and deteriorated siphons could be abandoned, all while not disturbing the environmentally sensitive Colorado River.

The SAR Transfer Station portion of the project on the south side of the Colorado River is equally as great an engineering challenge as it involved having to decipher record drawings of many old lines (some dating back to the 1940s) in order to determine the best way to bypass and decommission the existing lift station.