The Reuse Loop Hoops

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ABSTRACT
The San Antonio Water System owns and operates the nation's largest recycled water distribution system, which is tied to several major water recycling centers and constructed as a 'reuse loop' around almost the entire metropolitan area. In addition to providing recycled water to commercial and industrial customers, the dual-use system also provides streamflow augmentation and environmental enhancement discharges to the San Antonio River and Salado Creek. If operated as planned, effluents from several facilities would be commingled before discharge to receiving waters. Since effluent commingling is not allowed under current permits, SAWS began working with state and federal regulatory agencies in 2002 to develop an innovative, first-of-its-kind integrated municipal permit that would be one of the first issued in support of EPA's Watershed-Based Permitting Policy. It would also support Texas State Water Plan goals for water reuse and provide SAWS with operational flexibility and system redundancy. Initially, state regulators were highly supportive. After four years of negotiations and permit development, the Texas Commission on Environmental Quality (TCEQ) determined it could not implement EPA's Watershed-Based Permitting Policy because it could potentially lose significant revenues from Water Quality Assessment Fees. SAWS is currently awaiting issuance of standard permit renewals and will renew negotiations on an integrated permit when these are received. The distribution system will not be operated as a 'reuse loop' as planned. The structure of TPDES permits is among the many issues that Texas will have to address if the state intends to support effluent reuse.

BACKGROUND
San Antonio effluents are groundwater based and the in-stream flows in the area are heavily dominated or entirely dependant on wastewater effluents. In 2006 the San Antonio Water System (SAWS) completed the final phase of construction of the nation’s largest recycled water distribution system. To reduce dependence on the Edwards Aquifer, and in support of State Water Plan objectives for reuse and conservation, SAWS has invested over $140 million in almost 85 miles of large diameters mains, tanks, and pump stations to provide tertiary treated effluent for reuse. The system has the capacity to deliver 35,000 acre-feet per year to industrial and commercial customers (Figure 1).

Additionally, the system uses the same infrastructure for delivery of water to points in the San Antonio River and Salado Creek for streamflow augmentation. Three new 'remote' discharge locations were constructed for the purpose of environmental enhancement and conservation of potable supplies. A fourth discharge location is nearing completion of construction. The San Antonio River Walk, one of the state's top tourist attractions, was supported by Edwards Aquifer wells and new regulations would limit future use of the wells. Further, regulations would require the complete cessation of Edwards Aquifer flow to the river under drought conditions. At strategic locations, recycled water discharges have replaced use of potable water for baseflow maintenance. Since recycled water discharges commenced in 2001, significant environmental benefits have been quantified and applauded by state and federal agencies.

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