Table 4.2. Natural Sediment Delivery Compared to Proposed Sediment Volumes.
Natural Sediment Delivery
Proposed Sedimentation by BEACON
Beach Fill Site
630,000 1,510,000 2,140,000
Source: Noble Consultants, 1989
(1) Assumes 70% fines per BEACON report (1989) for the Santa Clara River.
(2) 25% for Goleta Beach and Ash Avenue and 35% for all other beach fill sites.
Beach fill material will be consistent in color with existing beach sand after the material has been
washed and reworked by waves, bleached under exposure to the sun and the marine environment,
and mixed with the existing sand. The USACE Shore Protection Manual (USACE 1984) states
that "...fill material darkened by organic material (Surfside/Sunset Beach, California) or
"reddened" by oxidized clay minerals (Imperial Beach, California) will be bleached quickly by
the sun to achieve a more natural beach color."
As demonstrated by the Ponto Beach demonstration project in Ponto Beach, California
(Sherman, et al. 1998), beach fill that is significantly darker in color then the existing beach will
be rapidly reworked by waves if placed seaward of the mean high tide line, leaving the material
that is sand-sized and sand-colored on the beach and in the nearshore environment. However, if
BEACON chooses to proactively address color changes prior to beach placement, several
planning options are available. The options include designing the project to place the material
below the mean high tide line during construction, and/or implementation of a public information
program (See Section 3.0). It is important to note, however, that color incompatibility alone
presents no adverse physical or chemical effects to the coastal environment. As a result, material
lacking in color compatibility will still be considered as a candidate for beach fill.
Moffatt & Nichol Engineers