Texas Groundwater Protection Committee

Western Shandong Province, China, covering an area of 83,700 km², is a study area that contains various representative hydrogeological conditions. The development of accurate and detailed large-scale hydrogeological models remains a significant challenge, with limited scientific and effective solutions available. To mitigate that challenge, a refined building method for regional hydrogeological models based on hierarchical modeling idea was proposed. In this framework, each preceding model constrains the subsequent one. Additionally, a systematic design for structural and attribute models was conducted before modeling, based on hydrogeological conditions and data distribution. This ensures precise characterization of geological objects while minimizing data requirements. Calculation methods for predicting groundwater resource storage variables and single-well water inflow were explored based on hydrogeological attribute models. The hydrogeological structure and its internal attributes at the regional scale were described in detail using the aforementioned methods. The prediction results of groundwater storage variables and single-well water inflow based on attribute models may improve forecasting accuracy to some extent. These findings provide a valuable reference framework for the efficient and accurate construction of large-scale hydrogeological models and promote the further application of 3D geological modeling in hydrogeological computations. • A refined building method for large-scale hydrogeological models was proposed. • A systematic design for structural and attribute models was conducted before modeling. • The modeling results accurately reproduce the spatial structure and internal attributes of four types of aquifers. • Groundwater storage variables and single-well water inflow were calculated based on the attribute models.

Editor-in-Chief ’s Note: September 1 of every odd-numbered year is the date when most new legislation from the most recent session of the Texas Legislature typically goes into effect. With this in mind, the Texas Water Journal invited seven organizations that work closely with the Texas Legislature to provide their take on the changes to Texas water policy and law that were made during the 2023 session. The opinions expressed in these summaries are the opinions of the individual organizations and not the opinions of the Texas Water Journal, the Texas Water Resources Institute, or the Bureau of Economic Geology.

Editor-in-Chief’s Note: September 1 of every odd-numbered year is the date when new legislation from the most recent session of the Texas Legislature typically goes into effect. With this in mind, the Texas Water Journal invited five organizations that work closely with the Texas Legislature to provide their take on the changes to Texas water policy and law that were made during the 2019 session. The opinions expressed in these summaries are the opinions of the individual organizations and not the opinions of the Texas Water Journal or the Texas Water Resources Institute.Organizations:• Sierra Club, Lone Star Chapter and Save Our Springs Alliance• Texas Water Conservation Association• Texas Alliance of Groundwater Districts• Texas Rural Water Association• Texas Water Infrastructure Network Citation: Kramer K, Mullins C, Robbins D, Steinbach SA, Martinsson L, Hightower T, Fowler PL. 2019. Commentary: 86th Texas State Legislature: Summaries of Water-related Legislative Action. Texas Water Journal. 10(1):75-100. Available from: https://doi.org/10.21423/twj.v10i1.7100.

Editor’s Note: September 1 of every odd-numbered year is the date that new legislation from the Texas Legislature session that ended the previous spring typically goes into effect. With this in mind, the Texas Water Journal invited five organizations that work closely with the Texas Legislature to provide their take on the changes to Texas water policy and law that were made during the 2011 session. The opinions expressed in these summaries are the opinions of the individual organizations and not the opinion of the Texas Water Journal or the Texas Water Resources Institute. Organizations: • Sierra Club, Lone Star Chapter • Texas Alliance of Groundwater Districts • Texas and Southwestern Cattle Raisers Association • Texas Farm Bureau • Texas Water Conservation Association Citation: K Kramer, SA Steinbach, J Skaggs, B Howe, D Robbins. 2011.Commentary: 82nd State Legislature Regular Session: Summaries of water-related legislative action. Texas Water Journal. 2(1):23-38. Available from: https://doi.org/10.21423/twj.v2i1.5886.

To further our understanding of the groundwater-to-indoor-air exposure pathway, a database of 270 paired groundwater and indoor air measurements of volatile organic compounds (VOCs) from 31 sites has been compiled and analyzed. Using regression analyses, these data have been analyzed to (1) detect evidence of indoor air impacts from dissolved petroleum hydrocarbons or chlorinated solvents in underlying groundwater, (2) estimate the true attenuation factor for volatilization from groundwater to indoor air, and (3) assess the utility of popular groundwater-to-indoor-air transport models for evaluating this exposure pathway. Key findings include the following: (1) > 95% of the indoor air concentrations fall within or below the range of national background indoor air values; (2) there is no correlation between petroleum constituent concentrations measured in groundwater and the concentrations of these VOCs in indoor air of overlying structures; and (3) for chlorinated solvent cases, a correlation between groundwater and overlying indoor air is observed; however, the average true attenuation factor, after correcting for background, is approximately 6.9 × 10−5, well below the default 1 × 10−3 value used by USEPA Vapor Intrusion Guidance to determine groundwater screening levels.

Over the past five years risk-based corrective action (RBCA) has become a more important approach for managing releases of chemicals to the environment. One of the key forces behind this transformation has been the efforts of American Society for Testing and Materials (ASTM) committee members who have developed standardized frameworks for implementing RBCA programs. Currently over 40 states are considering adoption of RBCA procedures for management of corrective action at USTs (Underground Storage Tanks) based on an XSTM (American Society of Testing and Materials) standard issued in 1995. A new ASTM Standard, Standard Provisional Guide to Risk-Based Corrective Action” (I’S 104-98) was issued in 1998 and supercedes the older petroleum release standard. The new standard is more generic, and addrtsses a wide variety of chemical releases to the environment. Overall, the new focus on risk-based approaches is a positive development. A risk-based approach means environmental cleanups can be conducted on a rationale manner based on tht! actual risk that the site poses to society, and allows for a flexible approacl- to managing those risks. Movement towards risk-based approaches does raise a concern that they will impose greater complexity on site evaluation processes, with significant variability among states. However, software tools can help to make make it easier to implement RBCA approtiches at a wide variety of sites.