Storm Water

Water Quality Success for LOWE's Southwest Austin Store

In June of 2003, Cunningham-Allen, Inc. (CA) was retained to work in conjunction with the project Civil Engineer on the design and permitting of the new Lowe’s store in Southwest Austin.

The project site is in the Edwards Aquifer Recharge Zone and in the Barton Springs SOS Zone. These are environmentally critical areas established by the Texas Commission on Environmental Quality (TCEQ) and the City of Austin (COA), respectively, and require additional water quality measures and permitting.

In particular, the Barton Springs SOS Ordinance imposed a “zero degradation” standard to storm water quality, meaning that water quality measures had to ensure that the quality of the storm water runoff flowing over the improvements has been returned to its pre-development condition before it is released from the site.

CA was very familiar with these design requirements because we had worked with the City of Austin on developing water quality measures for one of the first projects that had to comply with this new ordinance.

For the LOWE’S project, we worked in conjunction with the project Civil Engineer and designed a system that collected all the storm water that runs off the impervious cover (such as roofs and parking lots) and directed it to a retention basin. Storm water is allowed to settle in the retention basin for 12 hours, then it is pumped via a pumping system to be irrigated over an area of the site that had been dedicated for this purpose and left undisturbed. The size of the irrigation area was calculated based on the estimated volume of runoff (or water quality volume) and the estimated soil infiltration rate such that the entire water quality volume infiltrates the soil and is naturally treated through the existing vegetation’s root system and other microorganisms. As an additional measure of safety, berms were constructed downstream of the irrigation field such that runoff, if any, is captured and recycled through the retention pond and irrigation system.

This design, known as a “retention/re-irrigation system” was submitted to the COA and was approved with minor modifications.

As mentioned above, the project was also under TCEQ’s jurisdiction, which required specific permitting for storm water and wastewater. CA prepared the necessary permit applications and assisted the Owner in securing these approvals as well.

Finally, CA was excited to participate with the Owner, the project Architect, and the Civil Engineer on this project to assist them in securing a Bronze Certificate for LEED design (Leadership in Energy and Environmental Design) based on the innovation and effectiveness of the water quality system.