ASSESSING SUPPLEMENTAL UNCONFINED AQUIFERS AS POTABLE GROUND WATER RESOURCE IN CENTRAL TEXAS, MCLENNAN COUNTY

This presentation describes research assessing Brazos River alluvium and terrace aquifers (BRATA) in McLennan County in order to provide additional water for local residents. In McLennan County, Lake Waco and the confined Trinity aquifer are the primary potable sources for community water. In parts of the county, the Trinity aquifer groundwater chemistry is above acceptable potable USEPA arsenic drinking water concentration levels. In addition, the Trinity aquifer has about ten feet per year of water level decline due to recharge being less than groundwater pumping discharge. Lake Waco water requires pipelines and new users may have limited access during droughts. Thus, the need to assess and find other sustainable water supplies, such as, shallow unconfined fluvial terrace and alluvium aquifers. Two funded research projects have studied the suitability of the unconfined BRATA, a county-wide evaluation with the Southern Trinity Groundwater Conservation District (STGCD), and a specific study focused on a rural community water supply performed by a student intern provided by an engineering consulting firm. From an educational viewpoint, the intern and other students provided exposure to groundwater assessment research methods normally used in industry. The assessment methodology included: a search of the literature and published databases, department Geoprobe® drilling rig to confirm unconfined aquifer properties, making water-level measurements, water quality sampling and well hydraulic testing. Finally, the above BRATA assessment reports were orally presented to the STGCD and engineering firm with our findings. These projects have provided improved understanding of the BRATA for potential water supply and educated students as professionals.