EIR: Appendix H. Coastal Consistency Determination •
APPENDIX H.
COASTAL CONSISTENCY DETERMINATION
FOR i'i
RANCHO PALOS VERDES FEASIBILITY STUDY
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JUNE 2000
•
• DETERMINATION OF CONSISTENCY
with the
California Coastal Act of 1976
Rancho Palos Verdes Feasibility Study
Rancho Palos Verdes, California
June 2000
Introduction
The following Coastal Consistency Determination is prepared in compliance with the Federal
Coastal Zone Management Act of 1972, Section 307 (16 USC 1456(c)), which states that Federal
actions must be consistent with approved state coastal management programs to the maximum
extent practicable. The California Coastal Act is the state of California's approved coastal
management program applicable to the proposed project. To document the degree of consistency
with the state's program, the Act and Federal Regulations (15 CFR 930.37) require the
preparation of a Consistency Determination(CD)whenever a project could directly affect the
coastal zone. This CD provides a description of the Proposed Action, identifies each relevant
policy of the California Coastal Act, discusses the proposed action's consistency with each of the
policies, and where applicable, describes measures, which when implemented, will result in project
consistency with state policies to the maximum extent practicable.
• Project Description
The proposed action involves the construction of a 2500-foot-long dike located 400 feet seaward
from the existing bluff toe and"surrounds" the Portuguese Bend slide area on the Palos Verdes
Peninsula(Fig. 3.la of the DEIS). The dike is located at about the -16 MLLW contour line and
the highest crest elevation is about +24 ft. MLLW.
Dike Construction. The dike has a core of quarry run material to +6 ft. MLLW to retain sediment
to the Mean Higher High Water(MHHW) tide level, thereby preventing or significantly reducing
the landslide sedimentation potential downcoast. Depending on the location along the structure,
different layers of stone are prescribed as armor stone. The stone gradation and quantity, armor
stone crest widths and thickness of typical cross sections of the dike are described in detail in the
Coastal Engineering Appendix - Section 7 (see Volume II).
Rock for the construction of the dike would come from either a mainland quarry or a quarry on
Catalina Island. Rock obtained from a mainland source would be trucked to the project site.
Rock obtained from Catalina Island would be delivered to the site by a barge. Ocean based rock
placement would be from the floating barge with a crane except from stations 0+00 to 5+00 (see
Fig 3.2a of the DEIS). Land based construction is expected for this portion of the dike.
Construction would progress from the closest to shore seaward. Annor stone would be keyed
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into position such that the long axis of the stone is perpendicular to the face and center line of the
dike. •
For the ocean-based operation, it is assumed that the-10 ft. depth is adequate for barge
operations without compromising the barge's loading capacity. No excavation is expected to be
required except for the area between stations 0+00 and 5+00.
Maintenance. It is estimated that approximately 7 million cubic yards (cy) of material will need to
be removed from behind the nearshore dike every 50 years as landslide material migrates toward
the dike. Part of the material behind the dike is expected to be submerged in the water behind the
dike, and part of the material is expected to be dry material adjacent to the landslide bluff.
Material from behind the dike would be removed by loaders,truck mounted crawler cranes, and
dozers. Material is expected to be suitable for disposal at the LA-2 disposal site. Transport of
material from the dike to the disposal site would be: via conveyor to scow barges mored off the
dike which are then towed to the LA-2 site, or via trucks to barges berthed at Los Angeles or
Long Beach Harbor where barges are towed to the LA-2 site. (see Coastal Enginerring Appendix,
Section 7.2.4).
Project Location
The Study Area is located along the south central coastline of the Palos Verdes Peninsula in the
City of Rancho Palos Verdes, California, about 20 miles south of the City of Los Angeles (Fig.
1.1). The boundaries of the Study Area are defined by the coastal zone below Palos Verdes Drive •
South in the limits of the City of Rancho Palos Verdes. As stated above, the proposed dike is
located in Portuguese Bend in the City of Rancho Palos Verdes, California.
The LA-2 ocean disposal site was officially designated for disposal of dredged material in 1991.
L A_2 is located near the of the continental shelf, 7.7 miles (A 7 nautical miles) south nfthe
vv�aw� edge � \
San Pedro Breakwater. The area of the site is approximately 2.38 square miles, and the water
depth varies from 387 to 1,050 feet. This site is used for material that is too silty for disposal
within the littoral zone.
Project Need
The purpose of the Rancho Palos Verdes Feasibility Study is to determine the Federal interest in
measures to restore the marine environment of Portuguese Bend Cove and adjacent areas. Due
to the landslide movement at Portuguese Bend, which has moved material 200-400 feet into
Portuguese Bend Cove, the previous sub-tidal hard bottom habitat has been covered with
landslide debris and sediment eroded from the shoreline by waves and tide, and nearshore and
offshore areas have been impacted by siltation and turbidity. The study focus is on controlling the
sedimentation and turbidity in the nearshore and offshore zones that result from erosion at the
shoreline, which impacts the marine biological community of the area(see Fig. 2.1 of the DEIS).
Since the Corps has no authority relative to landslide abatement, the measure(s).identified are not
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• to have any effect on the existing landslides of the area. (Also see Section 2.1 of the DEIS for a
more detailed discussion of Purpose and Need.)
Prior to the 1950's, rocky reef areas and many intertidal pools were present along the shore and in
the nearshore area from Abalone Cove, around Portuguese Point and Inspiration Point, and
through Portuguese Bend to Bunker Point. These are now silted and smothered to a lesser or
greater degree by landslide-generated sediment. Portuguese Bend supported a rich and diverse
marine flora and fauna typical of Southern California intertidal and subtidal communities.
Unaffected rocky reefs adjacent to Portuguese Bend (e.g., Palos Verdes Point) support an
extremely productive kelp forest; they serve as a graphic reminder of the diverse biological
community that is lost to the extensive sedimentation and turbidity caused by the eroding landslide
bluff. (Wilson et al 1980:85 & 90; Stephens, personal observations cited in Pondella and
Stephens 1998:C-1; Stephens 1990: pg. C-2-1;Pondella et al. 1996:61) (For information on the
historic kelp canopy coverage on the Palos Verdes Peninsula - see North 1983:150; Wilson et al.
1980:84; and Wilson and Togstad 1983:306.) (Note that the Literature Cited in this Appendix
appears in Section 9 of the DEIS).
As the vast majority of shallow marine substrates in southern California are unconsolidated sand
or mud (as much as 95 percent by an MBC 1988 estimate), soft bottom habitat is not a unique
habitat-type in the study area. Natural hard rocky reef, however, is an extremely rare, productive,
and valuable habitat-type. Natural hard rock habitat is so rare and valuable that California
Department of Fish and Game's (CDF&G)Marine Resources Divisions has a program to create
• and improve artificial reef habitat to augment the scarce natural reefs (cf. Carlisle et al. 1964,
Lewis and McKee 1989, and CDF&G 1998). As natural rocky reef habitat is so rare and supports
a large, diverse assemblage of marine plants and animals, any effort to restore damaged or
degraded natural reef habitat would be extremely beneficial to the marine biological community
and is of great interest to resource agencies such as CDF&G and National Marine Fisheries
Service (NMFS).
Determination of Consistency
The following Determination of Consistency is prepared in compliance with the Federal Coastal
Zone Management Act of 1972, Section 307 (Title 16, U.S.C. Section 1456(c)), which states that
Federal actions must be consistent with approved state coastal management programs to the
maximum extent practicable. Sections of the California Coastal Act of 1976 that are applicable to
this project, as determined by the Los Angeles District, include: Article 2 -Public Access
(Section 30210); Article 3 -Recreation(Section 30220-30224); Article 4 -Marine Environment
(Section 30230-30235); and Article 5 -Land Resources (Section 30240). This Consistency
Determination summarizes the Rancho Palos Verdes Feasibility Study DEIS/DEIR. The
DEIS/DEIR provides greater detail on the proposed project, the existing environment, and the
project's potential environmental effects.
It is the opinion of the Los Angeles District Corps of Engineers, based on a review of the
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applicable sections of the Act, and on the data presented in the DEIS/DEIR prepared for the
Feasibility Study, that the proposed action is consistent with the California Coastal Act of 1976, •
to the maximum extent practicable. This Determination of Consistency has been prepared with
the following applicable sections of the California Coastal Act of 1976:
a. Article 2 -Public Access (Section 30210):
Since there is no public access to Portuguese Bend, the proposed dike construction would have
no impact on the public's ability to access the beach. (Also see section 4.4 of the DEIS/DEIR.)
b. Article 3 -Recreation (Sections 30220-30224):
Once very popular to the local residents, recreational use at the private Portuguese Bend Club has
diminished due to the deterioration of the beach by the adjacent landslide. (Note that there is no
public access to the beach at Portuguese Bend.) The area is now used mostly for family picnics
and barbecues by the Club's 200 member families. The proposed action is not expected to
significantly affect any land based public recreational usage. Whatever minor recreational usage
(e.g., sunbathing, tide pool viewing, swimming) that currently occur along the 1800 feet of
shoreline that would be enclosed by the dike would be lost. This impact is considered adverse,
but not significant as these are minor usages by local residents.
Should turbidity and sedimentation be reduced as expected, the area may, once again, become a
popular site for snorkeling and scuba diving. The natural calm ocean conditions of the cove made •
the area a popular site for those recreational pursuits prior to increased sedimentation and
turbidity. Significant beneficial impacts to this recreational activity are expected to result from
implementing the proposed action.
Impacts from the deposit of suitable material dredged from the Pogrtuuese Rend area at L A-2
b" b"
would be negligible, considering the frequency of discharge and the fact that only a small area
would be affected at any one time. Several years of site monitoring data at LA-2 indicate that
dredged material disposal has no discernable impact on commercial or recreation fisheries in the
area(MEC 1994). Disposal has occurred in the area since 1978. Commercial fish catch statistics
were analyzed over the 16-year period from 1970 to 1985 to evaluate the significance of fish
resources at LA-2 and surrounding areas, and to determine if dredged material disposal has had a
discernable impact. The recreation fish catch was similarly evaluated over a 10-year period.
Based on this analysis, the proposed dredging and disposal project is also expected to have no
effect on commercial or recreation fisheries at LA-2.
The recreation activity most likely to be affected by use of the LA-2 disposal site is pleasure
boating, particularly for boats traveling from Los Angeles and Orange County harbors to Santa
Catalina Island. However, the dredge would dump its load quickly at the LA-2 site and so, for
the most part, would be just one other vessel moving about in the offshore area. Sportfishing in
the area is rare due to the depth, so there should be little or no impact on that activity.
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• c. Article 4 -Marine Environment (Sections 30230-30235):
Water Quality
Water Quality Within the Dike. As the area behind the dike gradually fills with landslide material,
the quality of the water enclosed in the dike is expected to be adversely affected. The most
adverse conditions (i.e., a decline in dissolved oxygen concentrations)would probably occur
during the summer months as stratified water behind the dike might create biologically stressful
conditions for marine organisms. During this time period dissolved oxygen might be expected to
drop to 2-5 ppm (from the exiting 9-10 ppm). It is estimated, however, that at least 25% of the
volume of water behind the dike would be exchanged with each tide cycle as water moves
through the interstitial spaces of the dike above its impervious core (see Coastal Engineering
Appendix- Section 7.5.2). Although adverse, anoxia or hypoxia(dissolved oxygen of 0 ppm or
from 0-2 ppm)is not expected for behind-the-dike waters, and significant impacts are not
expected. During the Preconstruction Engineering and Design (PED) phase a more quantitative
evaluation of the movement and exchange of water behind the dike is proposed to further verify
this assessment. (Note D.O levels that constitute anoxia, hypoxia, and biological stress used are
as defined in NOAA 1998:3).
Water Quality Outside of the Dike. The proposed dikes are intended to trap all of Portuguese
Bend derived sediment and turbidity. The ocean waters outside of the dike are expected to
• become free of all turbidity caused by erosion of Portuguese Bend landslide material; significant
beneficial water quality impacts are expected from eliminating near-constant turbidity caused by
eroding landslide material from the water column of the study area.
Impacts from Dredging and Disposal of Dredged Material. Maintenance dredging is expcted to
be needed every 50 years to remove the seaward extent of the slide that is expected to encroach
within 50 feet of the dike during that time period. The dredging of material behind the
containment dike is not expected to impact local water quality, as any dredge-generated turbidity
will not escape the containment dike.
Disposal impacts at LA-2 would include temporary increases in turbidity and suspended solids,
along with associated decreases in dissolved oxygen. These water column conditions may
contribute to a decrease in light penetration. Most such impacts would be confined to the
immediate vicinity of dredging activities, with turbidity levels dissipating rapidly through
resettlement. The high percentage of silts would cause some sediments to remain suspended in
the water column for a period of time. Average surface water column concentrations in the
vicinity of a dredge are generally less than 100 mg/1 (LaSalle, 1991). Oceanic currents at the LA-
2 disposal site would aid in dilution and dispersal of the turbidity plume.
Significant changes to without-project water quality at the LA-2 disposal site from the
resuspension of pollutants, toxic materials, or trace metals are not expected. Even without the
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proposed action, sediment is being mixed by bioturbation and currents generated by wave surge •
and local circulation, and sediments are moving and mixing throughout the study area(Sadd and i
Davis 1997:12 & 22; Drake et al. 1994:8;Kayen et al. 1994:8). The propoosed action, therefore,
is not expected to affect the bio-availability of the low level of contaminants in the nearshore
sediment any differently than under without project conditions
Sediment Quality
Physical Quality. The quality of the marine sediment in the project area is discussed in sections
4.2.1 and 4.6.2 in the DEIS. Briefly, there is a fairly wide range of silt and clay fraction content
in the study area. Sediments with the lowest silt and clay fractions occur along the coast and in
the shallow and intermediate depths of Portuguese Bend near the southeast part of the area.
There is a general trend of increasing silt and clay in the offshore direction from east to west, with
sediment in the central part of the Bend characterized by a high percentage of silt and clay (50%
for most samples) (see Figures 7 and 8 of Sadd and Davis 1997 [provided as Appendix B]).
Chemical Quality. The chemical quality of the sediment in the Project Area is discussed in detail
in sections 4.6, 5.1 and 5.6 of the DEIS. The description and location of the effluent-effected
mound in some 50-60 meters of water offshore (and outside of the Study Area) are discussed in
detail in section 4.6.1 of the DEIS.
All of the existing, ongoing monitoring of contaminated marine sediment has been performed in
depths of 30 meters to 500 meters (cf L.A. Co. Sanitation District 1992; Lee 1994). As part of411
the sediment surveys performed for this feasibility study, contaminant sediment analysis was
performed nearshore sediment samples s1� the Study Area (see Appendix B of the DEIS).
V11V1111�\1 on heat J11V1 V JV4lment JalllY leJ in Study
Vibra-cored sediment samples were taken at five nearshore (7.6-17 m. in depth) locations in
Portuguese Bend and one location in Smugglers Cove. These six samples were further divided
into an upper, middle, and lower subsample. All 18 subsamples were analyzed fnr heavy metals,
pesticides, and organic pollutants as per EPA/USACOE (1993: Appendix D).
Chemical analysis of sediment show that cadmium and nickel occurred at all vibra-cored locations
in concentrations that could cause possible environmental effects as defined by Long et al. 1993
(i.e., the concentrations exceed the ERL [effects range - low] level). The highest concentrations
of these metals were found in the upper and middle layers of sediment in the central part of
Portuguese Bend. No metal concentrations, however, exceeded the ERM(effects range -
medium) level at any locations.
DDT and its derivatives (i.e., 4,4'-DDD, 4,4'-DDE, and 4,4'-DDT, and Total DDT) were also
detected in vibra-cored samples. DDE concentrations exceeded the 27 ppb ERM level at all but
one vibra-core location. (Levels that exceeded the ERL level of 2.2 ppb occurred at all
locations.) DDE was found in the upper, middle and bottom vibra-core sediment subsamples
(Sadd and Davis 1997:Table 6). Cores from the farthest east, however, showed an increasing
pattern of total DDT from top to bottom; westernmost cores had the opposite pattern. Sediment
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• rates and/or vertical mixing of sediment (by physical and/or biological processes)may explain the
observed patterns (Sadd and Davis 1997:22).
Dredged Sediment. In compliance with the Marine Protection, Research and Sanctuaries Act of
1972 (MPRSA) and the Clean Water Act of 1972 (CWA), testing of material taken from
proposed dredge sites will be evaluated under the"Evaluation of Dredged Material Proposed for
Ocean Disposal: Testing Manual" (i.e., the Green Book) (EPA/USACOE 1991)to determine if
material is suitable for disposal at LA-2. The disposal of the dredged material, if determined
suitable, will have no significant effect on marine biota at the LA-2 site.
Biological Impacts
Impacts to biological resources are discussed in detail in section 5.3 of the DEIS. No impacts are
expected to terrestrial biological resources. Significant net beneficial impacts to the marine
biological community are expected once hard rock reef is reexposed and landslide-generated
turbidity is eliminated from the project area (see section 5.3.2 of the DEIS).
The effluent-affected mound offshore the Palos Verdes Peninsula is not expected to be affected by
the proposed dike for reasons discussed in section 5.1 of the DEIS; the bio-availability of
contaminants in nearshore sediment is expected to be the same with or without the proposed dike
(see discussion in section 5.1 and 5.6 of the DEIS). As such, the proposed dikes are not
expected to affect existing sediment contamination or alter its bio-availability.
•
Endangered Species (Determination of No Effect)
Of the listed threatened or endangered species reasonably expected to occur in the study area(see
section 4.3.3 of the DEIS), only the least tern and the brown pelican may be affected by the action
alternatives. All other species are terrestrial, and no terrestrial impacts are anticipated from the
the proposed action. A more detailed analysis of the impacts to threatened and endangered
species appears in the Biological Assessment (Appendix J of the DEIS/EIR).
Since brown pelicans and least terns forage by plunge diving into ocean water, both species are
expected to benefit from the improved water clarity expected to result from the proposed action.
(No least tern nesting colonies occur in Portuguese Bend.)
In Southern California offshore dikes and breakwaters consistently provide high-capacity night
roost for brown pelicans (Jaques et al. 1996:45). The proposed dike may also serve as a night
roost for brown pelicans, but more likely be used by pelicans as a day roost area.
Containing sediment behind the proposed dike is expected to have no affect on the effluent-
affected mound offshore the Palos Verdes Peninsula. No "uncapping" of the contaminated
mound is expected, and contaminants associated with the mound are, therefore, not expected to
be any more biological available to threatened or endangered species than without the proposed
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dike. (Also see discussion in Section 5.6 of the DEIS)
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d. Article 5 -Land Resources (Section 30240):
The proposed action is not expected to impact any existing land use of the area. The action will
not affect the existing building moratorium, any current or future open-space or residential use
zoning, or any existing or future residential or commercial development in the study area.
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