Multi-source Water Supply Model and Source Development
The San Antonio Water System (SAWS), which has historically relied on the Edwards Aquifer as its primary water supply source, hired HDR to evaluate potential alternative water supplies following increased regulation of the Edwards Aquifer. HDR studied groundwater availability and water quality assessments in the Trinity Aquifer, Edwards-Trinity Aquifer, and in the Carrizo-Wilcox Aquifer. The assessments included data review and groundwater model development and simulations. It also led to a major test-drilling project in Gonzales County.
For evaluation of remote water supplies, HDR prepared preliminary designs for well fields, transmission, pump stations, and storage facilities. To balance the average and peak demands, terminal storage such as quarries and small reservoirs near San Antonio were considered. The design report also included the evaluation of an Aquifer Storage and Recovery facility with the development and testing of a groundwater model. Each preliminary design includes estimates of the capital and operating and maintenance costs.
To evaluate the complex water supply options, HDR developed the SAWS Multi-Source Water Supply Model to simulate the operation of adding new water sources to the existing system. The model interacts with a state-approved groundwater model that simulates aquifer pumping and drought management aquifer level targets to determine long-term water supply reliability. Based on model results, the user can allocate additional sources to meet projected water demand and determine projected utilization of new supplies for a range of hydrologic conditions.
SAWSs customers are accustomed to very high quality drinking water. To gain public acceptance of new sources, SAWS requested several water treatment assessments and studies of potential blending to address compatibility and maintain finished water quality.
The Multi-Source Model can function as a planning tool to select which water source to bring online next, a budgeting tool to forecast operation and maintenance costs, and/or an operational tool to determine what action should be taken to either avoid or mitigate adverse impacts to supply.