2.0 Alternatives Considered
Onshore Borrow Sites and Other Sand Sources
2.3.2
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Onshore sources ofmaterialwere also considered including: (1) dredging sand from behind Henshaw Dam,
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or other dams that act as sediment "sinks"; (2) removing dams that currently interrupt river-borne sediment;
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or (3) terminating regional sand mining activities that prevent sand from reaching the shoreline. Dredging
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sand from behind any dam and transporting that material to the shoreline would involve the use of trucks
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for transportation. A typical truck carries 14 cy of material. Receiver sites for this action would vary in
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size from 100,000 to 570,000 cy resulting in over 7,140 trips for the smallest site and over 40,700 truck
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trips for the largest site. Transportation and construction from onshore borrow sites would result in air
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emissions, noise impacts and conflicts with beach users for parking and access that resulted in its
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elimination.
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San Diego is a semi-arid region and precipitation is highly variable. The need for a consistent source of
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water has lead to the construction of dams on all major water courses in the region, except the Santa
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Margarita River. Since the late 1940s, local water sources have been supplemented by imported water
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which has been stored in reservoirs created by those dams (Pryde 1992). The local supply of water is
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limited and efforts continue to increase the amount of water storage and improve the delivery system. The
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San Diego County Water Authorityis currently implementing the Emergency Water Storage Project, which
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will provide additional local water supplies by constructing a new dam in Olivenhain as well as raise the
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height of the dam at the San Vicente Reservoir. The need for local water supplies for the growing
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population would make it infeasible to remove dams in the region and allow sediment to flow naturally to
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the ocean.
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Sand and aggregate mining in San Diego County is used to support the construction industry and provides
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raw material for making concrete, preparing road beds, and other uses. It is a necessary raw material also
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for road maintenance. The California Division of Mines and Geology Special Report 153 (n.d.) estimates
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a need for approximately 760 million tons of aggregate in San Diego County through the year 2030. If sand
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mining in San Diego were halted, or reduced, other sources would have to be found, mostly likely from
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Riverside and San Bernardino counties. This would necessitate additional truck trips to carry the material
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resulting in air and noise impacts, and there may not be enough material to support the localdemand. Given
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the economic importance of the construction industry, it would not be feasible to interrupt the local supply
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and wait for local material to make its way down the river system to the ocean.
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Page 2-8
Regional Beach Sand Project EIR/EA
99-69\SANDAG EIREA 3.4.wpd 7/17/00
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