4.1 Geology and Soils
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Table 4.1-2
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Estimated Location of Offshore Sand Bar and Project-Related Increase in Sand Bar Depth
Feet Above Average Historical Bar(1)
Offshore Bar
Alternative 1
Alternative 2
Range (feet from
Receiver Site
back of beach)
Average
Maximum
Average
Maximum
South Oceanside
600 to 1,750
0.3
0.6
0.3
0.6
North Carlsbad
350 to 1,700
0.7
1.4
0.7
1.4
South Carlsbad
500 to 1,700
0.1
0.2
0.4
0.8
(North and South)
Batiquitos
400 to 2,000
0.4
0.9
0.6
1.3
Moonlight Beach
600 to 1,800
0.4
0.8
Not measurable
Not measurable
Cardiff
700 to 1,800
0.1
0.3
Not measurable
Not measurable
Solana Beach
500 to 1,800
Not measurable
Not
Not measurable
Not measurable
measurable
Del Mar
700 to 1,450
0.5
0.9
0.5
0.9
Torrey Pines
500 to 1,500
0.4
0.8
0.4
0.8
At end of year 1, assuming average wave conditions
(1)
Note: Values are not included for Leucadia because historic profiles do not exist to calculate the sandbar. Values
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are not provided for Mission and Imperial beaches because numerical modeling was not performed due to
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simplified coastline conditions and lack of sensitive resources.
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Littoral Processes
For each receiver site situated within the South Oceanside Littoral Cell (i.e, South Oceanside to Torrey
Pines) sediment placed onshore would be distributed along the coast by the net littoral sand transport to
the south at approximately 100,000 to 250,000 cy per year. This downcoast net transport movement is
the difference between upcoast and downcoast sand transport rates, which are predominantly driven by
the angle of wave approach to shore.
South Oceanside. Alternative 1 involves placing approximately 380,000 cy of dredged sediment at the
South Oceanside receiver site. Previous placement of fills on the beaches in Oceanside have not shown
dramatic changes in the littoral process. Since 1955, over 13 million cy of fill have been placed onshore
or nearshore in Oceanside by the USACOE and the City with no adverse geologic or soils impacts
recorded. These past beach fills quantities have been in the same range as the proposed fill. Therefore,
based on past fill events, placement of sediment onshore at the South Oceanside receiver site would not
be anticipated to impact the littoral transport process.
Page 4.1-6
Regional Beach Sand Project EIR/EA
99-69\SANDAG EIREA 4.1 to 4.13.wpd 7/17/00
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