West Yost is developing a groundwater model for eastern Nevada
and western Utah. The work is being conducted jointly for the
U.S. Fish and Wildlife Service, U.S. Bureau of Land Management,
National Park Service, and U.S. Bureau of Indian
Affairs. The model covers an area of about 25,000 square
miles. The model will be used by theses agencies to assess
the impacts of proposed groundwater exports from the model
area.
West Yost is responsible for managing and directing technical
work associated with the feasibility of implementing an aquifer
storage and recovery (ASR) program for the City. This program
involves the injection of treated surface water (when available
during the winter months) into the groundwater basin for storage
and later extraction during peak demand periods or dry years.
West Yost is currently providing hydrogeologic consulting
services for investigation and aquifer performance testing of the
Lower Tuscan Aquifer as part of the Stony Creek Fan Conjunctive
Water Management Program, a multi-year research program in Glenn
County. The study will help characterize the extent, hydraulic
properties, water quality and sources of recharge in the Lower
Tuscan Formation and related parts of the aquifer system.
West Yost is supporting the City of Woodland’s (City) efforts to
expand and improve the quality and sustainability of its
groundwater supply. The City relies completely on
groundwater, which is produced from an intermediate depth
aquifer. The City is expanding its groundwater production to meet
projected water demands and improve water quality by constructing
new wells in a deeper aquifer zone which, locally, has superior
water quality. West Yost has evaluated hydrogeologic conditions
and groundwater quality, designed the wells, and provided
hydrogeologic support during construction. West Yost is currently
preparing a groundwater management plan for the City.
West Yost is supporting the City of Woodland’s (City) municipal
ASR well design efforts, and efforts to expand and improve the
quality of its groundwater supply. The City currently depends
completely on groundwater, which is produced from an intermediate
depth aquifer. The City is seeking to expand its groundwater
production to meet projected water demands and improve water
quality by constructing new ASR wells in a deeper aquifer zone
which, locally, has superior water quality, and will have the
ability to inject treated water supply from the future
Davis/Woodland Surface Water Treatment Facility.
West Yost evaluated the capacity of the deep aquifer zone
(approximately 700 to 1,500 feet below land surface) for future
water supply development by the cities of Davis and Woodland and
UC Davis. As part of this study, West Yost performed aquifer
tests using City and University production wells. The largest
test involved pumping at an average rate of approximately 2,500
gpm for 13 days.
West Yost provided design services for a new 6,000-gpm
groundwater supply in Sacramento County. Typical production
depths in the area yield groundwater with arsenic concentrations
that can approach or exceed the 10-µg/l federal Maximum
Contaminant Level (MCL). Deeper zones can contain concentrations
of manganese, iron and other constituents that exceed secondary
MCLs and can require treatment. Groundwater from the wells meets
all drinking standards. The wells were designed and constructed
to enable sealing of zones that may be affected by water quality
changes in the future.
West Yost conducted an initial hydraulic analysis of the
potential to blend the elevated uranium concentrations in one
well with water from other wells to produce an acceptable blended
uranium concentration (less than or equal to 80 percent of 30
mg/L MCL). Utilizing the City’s water system hydraulic model,
West Yost estimated the extent of possible dilution and
coordinated with City staff to develop a proposed well operation
plan and valving arrangement to force water from other wells to
the Smyrna Well vicinity.
