Water quality meters monitor the ASR well.
GSI helped the City assess the feasibility of aquifer storage and recovery (ASR) as a solution for managing costs by reducing reliance on purchased wholesale water during peak demand periods. We completed an in-depth proof-of-concept study involving exploratory well drilling and testing. We then worked with the City to obtain an ASR limited license and underground injection control permit from the state, and supported the design and installation of ASR Well No. 1 and subsequent pilot testing efforts. Since then, we have provided ongoing support for operations, well rehabilitation, troubleshooting, and permit compliance, including annual reporting and re-licensing.
During initial pilot testing of the injection system, the ASR well began showing signs of performance declines from biofouling. GSI helped diagnose the causes of diminished performance and identified that a low residual chlorine concentration combined with a high nutrient load in source water were contributing to create a favorable environment for biofouling in the well. GSI worked with engineering partners to evaluate and modify the City’s distribution system operations to eliminate the causes of the low chlorine residual and to restore well performance. The City resumed full-scale operational testing of the ASR well in 2011 and has successfully stored up to 100 million gallons in the basalt aquifer each year. The system modifications and operational changes have continued to maintain the performance of the well.
In addition to routine ASR operational monitoring, we recently identified and evaluated the effects of dewatering operations in a nearby quarry on the basalt ASR storage aquifer and the City’s ASR recovery capacity. We also have supported the City with developing and implementing water quality sampling plans to comply with successive phases of the Unregulated Contaminant Monitoring Rule under the federal Safe Drinking Water Act.
GSI's work involved: