Page 208 - _ 180314 Special Yucaipa GSA Packet

Edwin H. Lin, PG, CHG

Managed Aquifer Recharge Feasibility Study, Western Alto Subarea, Upper Mojave River
Basin, Mojave Water Agency
The Mojave Water Agency (MWA) is evaluating the feasibility of recharging State Water
Project (SWP) water in off-river surface spreading basins within the western Alto Subarea of
the Upper Mojave River Groundwater Basin (Basin). A successful managed aquifer recharge
(MAR) project in the region would increase MWA’s capacity to store and recover SWP water
and provide future long-term replenishment of the Regional Aquifer. Since 2016, Todd
Groundwater has been assisting MWA with field investigations to characterize the subsurface
stratigraphy and infiltration potential of the vadose zone, which extends down to 550 feet
below ground surface. As Project Manager, Mr. Lin designed and supervised the first phase of
field investigations, which included regional surface geophysical surveys and field-scale
infiltration testing complemented by borehole infiltration tests. Infiltration tests were
conducted at three sites by MWA staff under direction of Todd Groundwater, with test basin
2
geometries ranging from approximately 600 to 1,800 ft . Tests were conducted from 15 to 21
days. Results indicated that near-surface soils at all three sites are relatively permeable and
generally suitable for recharge through surface spreading basins. Average vertical infiltration
rates were 1.6, 4.3, and 11.1 ft/day for the three sites. The project is proceeding to the second
phase of investigation with drilling, installation, and groundwater quality sampling of two
sonic-drilled monitoring wells, evaluation of geochemical (leaching) properties of selected
vadose zone sediments, and borehole instrumentation to track the vadose zone wetting front
during future pilot-scale infiltration tests.

Managed Aquifer Recharge Feasibility Studies for Mid-Valley and CVWD Palm Desert Areas,
and Groundwater Replenishment Expansion Evaluation of the Thomas E. Levy (TEL) Facility,
Coachella Valley Water District
As Project Manager/Lead Hydrogeologist for three independent CVWD managed aquifer
recharge feasibility studies, Mr. Lin reviewed CVWD’s domestic pumping and recharge
operations to assess the feasibility of expanding groundwater replenishment through surface
spreading of Colorado River water in the West and East Whitewater River Subbasin Areas of
Benefit. For these studies, Mr. Lin obtained pertinent data from CVWD to characterize
lithologic, groundwater production, groundwater level, and water quality conditions across
60 mi2 of CVWD’s service area. Mr. Lin oversaw the construction of three local-scale
MODFLOW/MT3D groundwater flow and solute transport models used to simulate future
groundwater level and water quality impacts from proposed recharge. Results indicated that
desired recharge amounts could be accommodated in the Mid Valley and Palm Desert and
provide long-term water level and water quality benefits for nitrate and chromium-6. CVWD
is currently moving forward with environmental planning and final facility design at the Palm
Desert site. Results of the TEL study indicated that future District recharge, pumping and drain
operations could be optimized to maximize groundwater storage, recovery effectiveness, and
water quality.

Page 2 of 4
Yucaipa Groundwater Sustainability Agency - March 14, 2018 - Page 183 of 226