Groundwater Advisory Unit

1. Groundwater Protection Determination LettersNorman Gearhart, P.G.Manager Groundwater Advisory Unit

2. Groundwater Advisory Unit Purpose • Provide recommendations for groundwater to be protected during oil and gas drilling and production. • Evaluate Saltwater Disposal Well applications for geologic isolation from the base of usable-quality water and injection below the underground source of drinking water. • Hydrogeological evaluation concerning groundwater contamination.

3. Protected Aquifers For oil and gas wells • Freshwater (less than 1,000 mg/l total dissolved solids, TDS), and • Usable-quality water (less than 3,000 mg/l TDS, waters known to be used, and waters identified by the Texas Water Development Board for use in desalination) For saltwater injection wells in addition to the above • Underground source of drinking water (less than 10,000 mg/l TDS)

5. Types of Applications • Surface Casing Applications • Microseismic Applications • Seismic Applications (shot holes) • Saltwater Disposal Applications (W-14)

6. What Requires a Surface Casing Letter • New Drills • Well Integrity Test • Plugging and Abandoning • Cathodic Protection • Microseismic Boreholes • Re-entering a Well

9. Seismic Letter • Send a Dated letter Including • Company Name and Address • Contact Person and Phone Number • Project Name • County Name(s) • Shot Hole Depth • Map Showing Shot Points • Receive a Seismic Groundwater Protection Letter (Base of Usable-Quailty Water)

13. Carrizo Base of Usable-Quality Water Base Underground Source of Drinking Water

17. Contact Information