'Regional Beach Sand Project EIR/EA' by KEA Environmental, Inc.

1.0 Introduction

Silver Strand Littoral Cell extends from south of the international border to the Zuniga Jetty at San Diego

Bay and includes the shorelines of the cities of Imperial Beach and Coronado.

Within the littoral cell, sand can move up and down the coast as well as on and offshore. Sand can also

be carried by littoral drift into submerged canyons. For example, it has been estimated that Scripps

Submarine Canyon near La Jolla may, in some years, receives 220,000 cy of sand from littoral drift

(Moffatt & Nichol 2000a). Sand that drifts into submerged canyons essentially exits the littoral cell, and

it is no longer available to replenish beaches during the summer. The seaward edge of an active littoral cell

is defined as its "depth of closure." Substantial quantities of sand from coastal littoral cells do not usually

travel outside of this depth and into the deeper ocean. Correspondingly, sand outside the depth of closure

does not move back into the littoral cell. In San Diego, the depth of closure ranges from approximately -26

to -46 feet (Moffatt & Nichol 2000a). The proposed dredging activities would take sand from borrow

sites2 outside (deeper than) the depth of closure and place sand within the three littoral cells. The new sand

being introduced to the system is expected to remain within the respective littoral cells and enter the

seasonal cycle of beach loss and gain. Conversely, dredging inside (shallower than) the depth of closure

would merely relocate sand material already within the littoral cell. (More information on littoral processes

and coastal geology is found in Sections 3.1 and 4.1 of this EIR/EA.)

In response to the concerns about erosion voiced by citizens and communities up and down the coast, and

documented by the CCSTWS, SANDAG worked with member agencies to prepare the Shoreline

Preservation Strategy for the San Diego Region (SANDAG 1993). The Shoreline Preservation

Strategy is a strategy with a menu of solutions to address shoreline erosion including beach building by

placing large amounts of sand on eroded beaches, structures such as groin fields to help hold sand in place,

structures such as seawalls and sand berms to protect property, and policies and regulations regarding the

use of the shoreline and its development such as bluff top building setbacks. Further, these tactics are

divided into regional scale actions (beach building, redistributing sand via groins, breakwaters, etc.) and

local scale methods (requiring setbacks, bluff top erosion management via irrigation controls, seawalls and

revetments).

The Shoreline Preservation Strategy recommends further engineering, economic and environmental

design studies. It does not identify generalized locations for structures such as groins, but it does contain

recommendations for sand volumes to be placed in each of the three littoral cells along the San Diego

The term "borrow" refers to material to be taken from one location to be used as fill at another location.

Regional Beach Sand Project EIR/EA

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