West Yost has supported the City of Woodland’s (City) Aquifer Storage and Recovery (ASR) Program since 2010, conducting services directly for the City and for the WDCWA. Under the ASR program, the City is implementing a comprehensive ASR program to help address its water supply needs during periods of water right curtailments, peak demand conditions, and/or drought periods.
During the initial phases of the work, West Yost conducted feasibility assessments of alternative water supply sources to supplement a planned surface water supply from the Sacramento River. ASR was identified as the most feasible, least-cost alternative and a Work Plan for ASR Program development was prepared.
Implementation included the following:
Monitoring Network Construction and Baseline Monitoring
The West Yost team designed and acted as the City’s representative during the construction of the City’s ASR monitoring network. The team conducted baseline groundwater level and quality monitoring in network wells as part of the ASR program.
Quantification of Water Budget/Numerical Modeling
The West Yost team used the California DWR Modeling Support Branch’s Integrated Water Flow Model (IWFM) to develop a three-dimensional groundwater flow model for Yolo County. The model results supported ASR design efforts and preparation and adoption of the required CEQA Supplemental Environmental Impact Report (SEIR).
The West Yost team conducted geochemical modeling to establish the potential for plugging of the ASR wells or aquifer, and the potential for mobilization of naturally occurring constituents in the aquifer matrix, including hexavalent chromium.
ASR Injection Testing Using Isotopes and Noble Gases
The West Yost team conducted a stable isotope study to assess the age, movement, and mixing of recharged and native water in the aquifer.
Data Analysis, Interpretation, and Reporting
The West Yost team prepared a comprehensive report on the ASR program studies that was used to support the ASR program in the SEIR, and modification of the surface water right to allow the long-term storage needed for ASR operations.
State Water Resources Control Board Permitting for ASR
The West Yost team acted as the City of Woodland’s representative and prepared on the City’s behalf a Notice of Intent (NOI) to conduct short-term injection testing and a NOI to conduct pilot testing and operations under the State Board ASR General Order. Working with a water right attorney, the West Yost team prepared the technical content for the Underground Storage Supplement application, which was filed with State Board to modify the appropriative water right to allow the long-term storage needed for ASR operations.
ASR Well Design
The West Yost team designed and provided services during the construction of the City’s first ASR well, which won the 2013 ASCE Sacramento Section Sustainable Engineering Project of the Year Award and also won an APWA, Sacramento Chapter, Project of the Year Award. To achieve maximum flexibility, the well was designed and constructed to be used as a standard municipal supply well while also being ASR capable. The West Yost team provided hydrogeologic services during the design, construction and testing of the City’s next two ASR wells.
- Subsurface information was very limited during the initial stages of ASR feasibility assessment.
- Groundwater modeling challenges included developing 3-D representations of the subsurface geology and assigning pumping rates to private wells in agricultural and rural residential areas where pumping records are very limited or nonexistent.
(Banner image: West Yost identified the ASR production zone and constructed a numerical model of the aquifer system.)