4.1 Geology and Soils
Table 4.1-1
Predicted Retention Time of Beach Fill at Each Receiver Site
Approximate Time for Receiver Site to
Receiver Site
Return to Pre-Fill Condition (years)
South Oceanside
1 to 2
North Carlsbad(1)
4 to 5
South Carlsbad North
1
South Carlsbad South(2)
1
Batiquitos(1)
1 to 2
Leucadia (1)
1 to 2
Moonlight Beach(1)
1 to 2
Cardiff
4 to 5
Solana Beach
1 to 2
Del Mar
1 to 2
Torrey Pines
1 to 2
Mission Beach
2 to 3
Imperial Beach
2 to 3
Alternative 1 only.
(1)
Alternative 2 only.
(2)
Under average wave conditions
(3)
Source: Moffatt & Nichol 2000a
Near each receiver site, sediment would move from the beach to an offshore sandbar during the winter
season. Sediment movement after beach fill placement would follow natural seasonal and littoral trends.
A minor increase in the average sand thickness at the nearshore bar is anticipated for each receiver site.
Table 4.1-2 provides a summary of the location of the existing seasonal offshore sand bar and the increase
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in depth of that bar resulting from the project at the end of the first year. The increased depth is provided
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assuming average wave conditions and for average and maximum depths of cover. Appendix F contains
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a more detailed table with estimates for the full five year modeling. Generally, project related sediment at
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the bar is measurable only off North Carlsbad and Cardiff for that entire time period. No long-term
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significant impacts to coastal geology are anticipated due to sediment transport or the increased sediment
thickness at the existing, seasonal offshore bar.
Regional Beach Sand Project EIR/EA
Page 4.1-5
99-69\SANDAG EIREA 4.1 to 4.13.wpd 7/17/00
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