Groundwater Master Plan, and Well Siting, Design and Construction Management
City of Santa Rosa, California

For the last 13 years, West Yost team members have served as the City’s water resources consultant, working closely with City staff to provide technical support on water supply and groundwater projects/programs. This support has ranged from groundwater basin management planning and technical studies, through groundwater modeling, well siting, wellfield management, well rehabilitation, wellhead treatment, development of groundwater GIS support tools and Aquifer Storage and Recovery. Most recently, West Yost prepared the Groundwater Master Plan (GWMP) for the City which documents recommended policies and prioritized capital improvement program projects using the City’s available groundwater resources.

Key elements associated with the GWMP include: identification of specifically recommended short-term, mid-term, and long-term projects which must be implemented if the City is to reach its emergency groundwater supply production goals; establishment of a comprehensive GIS groundwater database; key interface with other on-going City programs: Exploratory Test Well Drilling Program, Water System Master Plan, Salt and Nutrient Management Plan and Stormwater Program; integration of the on-going field exploration activities to identify potential, future City emergency municipal well locations; preparation of an ASR well siting feasibility study; development of a key well groundwater monitoring network to establish baseline hydrologic conditions, and track future conditions in response to future groundwater management decisions; preparation of an Annual Groundwater Report Template, which is based on the identified Key Well Monitoring Network (also developed as part of the GWMP) and presents comparison tables of long-term and seasonal spring-to-spring water level changes to track both long-term and seasonal changes in groundwater storage; and preparation of an ASR Program well siting feasibility study.

Exploratory Test Well Construction Program: For the Exploratory Test Well Construction Program West Yost’s team oversaw the identification, siting, and construction of two test wells for the City. The intent of the effort was to identify lithologic formations and evaluate hydrogeologic characteristics with the goal of constructing an emergency municipal production well at each site. Two 1,000 foot deep test borings were drilled at two different City park sites, and based on the encountered aquifer materials and water quality results obtained from aquifer zone sampling, each boring was reamed and cased to a depth of approximately 700 feet. Both step-drawdown and constant rate aquifer pump testing and associated water quality sampling was conducted to determine aquifer hydraulic quality. Since the drilling was conducted in a very urban setting, the logistics of mitigating the noise and light generated by the drilling rig, handling and disposal of cuttings, drilling mud, development and test water, traffic control, site security,public notification/outreach, and site restoration were all issues that had to be properly addressed.

Additional Water and Groundwater Services: For the City, West Yost team members have also completed the following projects: Water Master Plan; Emergency Test Well Siting Program; 2005 and 2010 Urban Water Management Plan Updates; assisting City staff on water supply policy issues during negotiations with the Sonoma County Water Agency and drafting of the New Restructured Agreement; serving as the City’s technical representative for the joint USGS Santa Rosa Plain Groundwater-Surface Water Model Development Project; preparing the Engineer’s Report to the California Division of Drinking Water requesting that the status of Farmers Lane Wells 1 and 2 be changed from standby to active potable supply; evaluating the City’s additional storage needs, particularly within the Aqueduct Zone; conducting hydraulic water system modeling and analyses to meet fire flows in the City’s Hillside pressure zones; and other “on-call” water supply, infrastructure evaluations, design, and resource studies as requested by City staff.