Ground-Level Monitoring Committee Meeting December 1, 2016

Agenda Siting Study for the Pomona Extensometer Facility Background and Objectives Methods Results and Conclusions Recommendations and Next Steps GLMC Next Steps Review and comment on this report Upcoming meetings and reports

Data Gaps from the Hydrogeologic Conceptual Model Background Data Gaps from the Hydrogeologic Conceptual Model Lack of deep, high-resolution lithologic data Installation of two boreholes (shallow and deep) and each equipped with a dual-nested piezometer and an extensometer Lack of depth-specific piezometric data New installation of pressure transducers in existing wells New piezometers in areas of greatest observed subsidence Lack of depth-specific aquifer-system deformation data Extensometer installation and conduct controlled aquifer-system stress testing and passive monitoring Lack of knowledge of the pre-consolidation stress within the compacting intervals of the aquifer-system Extensometer installation Conduct controlled aquifer-system stress testing

Target Locations for the Pomona Extensometer

Dual-Nested Cable Extensometer Schematic

Background Design and Install the PX: Select a location for the PX Perform siting study to identify and rank potential sites Discuss construction and permanent easements with owners Conduct environmental review pursuant to CEQA Select a site for the PX Prepare technical specifications for PX Prepare bid package and incorporate technical specifications Acquire construction and permanent easements Conduct bidding process, and select and retain drilling contractor Construct and test PX; begin monitoring Prepare completion report for the PX

Methods Develop criteria to identify and rank potential sites Site-Identification Criteria Parcel-Ranking Criteria Acquire and compile information necessary to apply the criteria Utilize ArcGIS to apply the Site-Identification and Parcel-Ranking criteria Add ranking from each criterion to calculate total rankings

Site-Identification Criteria Must be within Target Areas Must have undeveloped space sufficient for construction and operation. Site must not have overhead obstructions that may prevent safe rig access and operation Site must be at least 1,000-ft from active production well. Site must be at least 300-ft from heavy-traffic streets and 50-ft away from light-traffic streets. Site must be required distances from infrastructure and facilities according to the DWR Bulletin 74-81 and Water Well Standards Bulletin 74-90. Must not have unresolvable environmental challenges.

Target Locations for the Pomona Extensometer

for the Pomona Extensometer Target Area A for the Pomona Extensometer

for the Pomona Extensometer Target Area B for the Pomona Extensometer

Parcel-Ranking Criteria Parcel Ownership Publically owned (Cities of Pomona or Claremont) Publically owned (other) Privately owned Proximity to maximum land subsidence (Mar-11 to Jan-16). Inside -0.24-ft contour Between -0.20-ft and -0.24-ft contours Outside the -0.20-ft contour Distance to nearest heavy-traffic street More than 1,000-ft 500-1,000-ft 300-500-ft

Potential Locations for the PX Parcels A and B

Recommendations Further evaluate top-ranked sites to determine the ultimate location of the PX: Parcels A and B were the highest ranked parcels. Parcels C, D, and E are acceptable alternatives.

Next Steps Design and Install the PX: Select a location for the PX Perform siting study to identify and rank potential sites Discuss construction and permanent easements with owners Conduct environmental review pursuant to CEQA Select a site for the PX Prepare technical specifications for PX Prepare bid package and incorporate technical specifications Acquire construction and permanent easements Conduct bidding process, and select and retain drilling contractor Construct and test PX; begin monitoring Prepare completion report for the PX

Schedule and Milestones – PX Siting Study December 22, 2016 Committee submits comments on the PX Siting Study tech memo Tara Rolfe trolfe@weiwater.com Andy Malone amalone@weiwater.com

Next Steps – Ground-Level Monitoring Committee Finalize Initial Hydrologic Conceptual Model and Monitoring and Testing Program for the Northwest MZ‐1 Area Report Draft Develop and Evaluate the Baseline Management Alternative (BMA) Draft Develop and Evaluate the Initial Subsidence- Management Alternative (ISMA) Scope and budget for the Initial Monitoring Program expansion Draft Technical Specifications for the PX