Agenda - City of Santa Monica

Additional Local Groundwater Opportunities
In addition to implementing the water conservation programs described above, the City
will also need to expand local groundwater resources. Currently, the City obtains local
groundwater from the Santa Monica Basin via five wells. These wells are located within
the Arcadia and Olympic Sub-basins, and can produce approximately 3,000 acre feet
per year (AFY). Additionally, there are five wells located outside of the City limits in the
Charnock Sub-basin with a combined production capacity of approximately 6,000 AFY.
However, since 1995, the City has had to purchase most of its annual water supply
needs from the Metropolitan Water District (MWD) as the Charnock well field was shut
down due to methyl tertiary butyl ether (MTBE) contamination. This supply is now being
used in the system after treatment at the Charnock Water Treatment plant. The total
groundwater production capacity from the Arcadia, Olympic, and Charnock sub-basins
is currently estimated at approximately 9,000 AFY.
Another study of the groundwater basin was recently performed by Richard C. Slade
and Associates, LLC (RCS). T he study suggests the City may have additional local
groundwater opportunities within the Olympic, Charnock and Coastal Sub-basins. The
Coastal sub-basin has not been utilized as a g roundwater source to date due to salt
water intrusion; additional treatment would be required to utilize water from this basin.
Additional efforts are needed to assess potential sites and derive the potential quality
and quantity of additional well production for the City's supply portfolio. Incorporating
the RCS study with the SWMP’s evaluations and discussions, has led to the following
preliminary recommendations for additional local groundwater production and treatment
facilities. These preliminary recommendations are:
• Expansion of the existing Arcadia Water Treatment Plant
• Design and c onstruct new Olympic Water Treatment Plant (Gillette/Boeing
Settlement Project)
• Rehabilitate old wells and drill additional new wells in the Olympic, Charnock and
Coastal Sub-basins
• Develop and i mplement improvements in treatment efficiency to reduce the
amount of water lost to brine disposal during treatment (reduction of brine water
losses from 18% to 9%)
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