Two Storm Water Treatment Units Work in Tandem Under New Retail Site
To protect the Edwards Aquifer in Texas, the site developer of the new Natural Grocers store in Georgetown, Texas decided to use two storm water management systems to provide a higher-than-usual rate of filtration and trapping of debris.
The Natural Grocers store is part of the 1,100-acre Wolf Ranch planned community, which has 2,400 single-family homes, 900 multifamily units plus shopping areas. Storm water quality standards for the development are established by the Texas Commission on Environmental Quality (TCEQ).
Running under most of south-central Texas - about 4,350 square miles - that includes San Antonio and Austin, the Edwards Aquifer is the main source of drinking water for nearly two million people and the primary water supply for agriculture and industry in the region. Because of its karst hydrogeology, chemicals and debris that enter the system can move through the aquifer and quickly contaminate the water. Aquifers in general can be easily contaminated when pollutants enter the recharge zone.
One of the prime goals for the developer of the 1.6-acre Natural Grocers property was to protect the aquifer as much as possible, and also provide maximum control for storm water runoff.
“Initially, our engineers looked at options including an open pond, along with a sand filtration system and standard large concrete detention basin underneath,” explained Kevin Beck, development manager for Equity Ventures Commercial Development (Topeka, KS). “Within the state of Texas and especially in and around Austin, there’s significant sensitivity to the environmental areas,” he continued. “This aquifer is of particular importance to the state and to the region, and therefore to protect it and still allow development, we wanted to go with the higher removal rates to be very protective of that aquifer.”
The storm water management system Beck decided on consists of two units that work in tandem and designed to handle a 100-year storm with a capacity of nearly 17,000 gallons of water.
The detention system with an installed volume of 2,255 cubic feet of water consists of 198 StormTech® SC-740 chambers with an Isolator Row. Water enters from one grate in the parking lot and goes into the StormTech Isolator Row, which is first area to trap sediments and other contaminants. The water then flows to the BayFilter™ Model 522 with six removable filters for additional treatment, and is discharged into the San Gabriel River. The BaySaver Technologies’ BayFilter system, which has TCEQ approval for unrestricted use over the Edwards Aquifer, is designed to remove fine sediments using replaceable spiral wound media filters. It meets the Edwards Aquifer Rules Technical Guidance on Best Management Practices RG-348.
“With this combined system,” Beck stated, “we were able to achieve 87 percent removal of Total Suspended Solids.” StormTech chambers and the BayFilter unit are products of Advanced Drainage Systems, inc. (ADS) (NYSE: WMS).
Installing the storm water management system underground instead of using the land for an open pond provided more parking spaces for the store. StormTech chambers provide live and dead load safety factors and superior structural integrity. Manufactured using polyethylene and polypropylene, the chambers are rated by ADS for a 75-year service life.
“Because this project is above the Edwards Aquifer that is the reason why we used the two StormTech systems we did,” Beck explained. “There are stringent guidelines regarding pollutant removal from storm water runoff in this area, which we exceeded, removing 87 precent of the particulates including oils, fuels, dirt and sand plus debris.”
Additional information about ADS can be found at: www.adspipe.com
Editor's Note: Scranton Gillette Communications and the SGC Water Group are not liable for the accuracy, efficacy and validity of the claims made in this piece. The views expressed in this content do not reflect the position of the editorial teams of Water & Wastes Digest, Water Quality Products and Storm Water Solutions.