The city of Austin Watershed Department presented its preliminary engineering report for flood mitigation efforts along Oak Knoll Drive at a public meeting Feb. 27.

Plans include adding storm drains and improving existing storm drains that project managers have said are outdated and not up to the city’s capacity standards. The increased drainage will lead to a detention pond the Watershed Department plans to construct behind the post office at Jollyville Road, project managers said. Runoff will also be directed beyond the detention pond to Walnut Creek watershed, the plan states.

Acquiring land for the detention pond will require approval from the federal government because the land belongs to the US. Postal Service.

“That will require working with the federal government, which takes a little longer than usual because it takes some extra steps,” Project Supervisor Reem Zoun said.

The project is funded by the city’s Drainage Utility Fund and considered a “high-priority” area of localized flooding, Zoon said. The project may also receive funding from a potential 2018 bond, however, it can be completed using solely drainage utility funding, if necessary.

Some attendees of the meeting raised concerns over the project’s ability to keep up with increased density limits proposed for the area in the third draft of CodeNEXT, the city’s land development code.

Zoon said the city’s existing land development code requires that new commercial and multifamily developments must not increase the “peak flow” of water created by the existing infrastructure on the property. The proposed draft of CodeNEXT requires even further flood mitigation efforts and requires that redeveloped land only create as much runoff as it would as an undeveloped site, meaning many sites would require detention ponds.

“CodeNEXT requires that you're going to not only not increase the peak flow off your site but you're going to have to go back to undeveloped condition,” Zoun said.

The project now enters the design and permitting phase, which project managers expect to last until 2021 after which construction will begin.

For more information, visit the project website.