EIR: Section 05 Environmental Impacts • SECTION 5 - ENVIRONMENTAL IMPACTS
5.1 INTRODUCTION
This Section of the Draft EIS addresses the potential environmental and socioeconomic impacts of
the alternatives. The impacts of the alternatives were evaluated relative to the existing baseline
conditions described in the previous Section(i.e., Section 4, Affected Environment) and the "Without
Project Condition Assumptions" identified below. This analysis attempts to identify all relevant
issues, including both adverse and beneficial effects of the project. For each environmental resource
(or issue area)potential impacts were identified and compared to predetermined significance criteria.
Significance was considered on both a regional and local level. Environmental Commitments (also
known as mitigation measures) have been presented to avoid or reduce significant adverse effects.
Each impact was classified based on the applicable significance criteria and mitigation commitment
effectiveness, as follows:
Class I - Significant; cannot be mitigated to a level that is not significant.
Class II - Significant; can be mitigated to an insignificant level
Class III - Adverse, but not significant
Class IV-No impact
Class V -Beneficial
• 5.1.1 General Impacts Common to the Action Alternatives
The action alternatives (i.e., the two containment dikes) are intended to contain sedimentation and
eliminate turbidity from entering the marine environment beyond the containment dikes. The
following discussion pertains to the potential impacts expected to environmental resources within the
dike, the potential beneficial impacts of reducing the sediment load and turbidity in the Study Area
(especially nearshore areas), and the potential impact that reduced sediment input into the marine
environment has on the effluent-affected mound offshore.
Within the dike impacts. It is assumed that all existing marine life would eventually become
smothered by the increasing sediment load contained within the dike, and marine life is expected to
be completely lost. The quality of the water behind the dike is expected to be adversely affected, but
some flushing/exchange of water is expected to take place above the impervious core of the dike.
(Approximately 25% of the volume of the water behind the dike is expected to be exchanged twice
a day [i.e., every tidal cycle].) Impacts to the quality of the water are expected to be adverse, but
not significant (See further discussion in Section 5.2.4.1 and see Plate 8 of Coastal Engineering
Appendix).
Benefits of Reduced Sedimentation. The thickness of the sediment covering subtidal areas of
Portuguese Bend is shown in Figure 5.1. (The information was generated by side-scan sonar images
• 5-1
taken of the Portuguese Bend Area[Dill and Norall 1995] and nearshore data is corroborated by the
findings reported in Sadd and Davis [1997] [see Appendix B].)
In this impact analysis,it is expected that, if new sedimentation could be contained by the containment
dikes - natural marine erosive process (i.e., waves and currents) would eventually remove existing
sediment to, at least,the-30 foot MLLW depth contour and re-expose the underlaying hard bottom
(Areas 2, 3, and part of Area 5; see Fig. 5.1). (Also see Coastal Engineering Appendix- Section
7.3.8.)
The time estimated for waves and currents to naturally uncover the underlaying hardrock reef once
the proposed dikes are constructed varies from a 8 to 14 years for shallow areas (depths less than -20
MLLW) to 53 to 87 years for sediment in deeper waters (i.e., from-20 to -30 MLLW) (Table 7).
(The only difference between Alternatives 1 and 2 is that fewer hard rock acres in the shallow parts
of Portuguese Bend are available, and they become exposed sooner.)
Table 7. Time needed to naturally uncover various nearshore hard rock reef areas in the
Study Area-Alternatives 1 & 2 (adapted from Coastal Engineer Appendix- Table 24).
Depth Range Area I Volume Time to
Location' IILWj (acres) (cu yds) Uncover(yrs,)
l0 to -20 23b 93,318b 14b •
Portuguese Bend I I (13)° I(52,550)c I (8)C
(Area 2)
-20 to -30 28 334,626 87
IPortuguese Bend -20 to -30 11 33,991 9
(Area 3)
Bunker Pt. to Whites -10 to -20 18 70,686 11
Pt. (Area 5)
-20 to -30 17 201,398 53
'See Figure 5 1 for locations:;b Area under Alternative 1;
'Area under Alternative 2.
To expedite the restoration process, an option to dredge the sediment off of covered reefs in Areas
2 and 3 is analyzed (Alternative la and 2a). Under this option, uncovering of hard rock in Areas 2
and 3 would be immediate once dredging has been completed. (Note that Area 5 has a kelp
41,
5-2
• • •
A. .
Q4, Ci a4, :_ Figure 5.1 S(Medimentodifiedfrom ThiCoastalcknessEngioverneering BedroAppendix ck-&see Areas
11, of
Plate Potential8) Restoration.
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.4MAJOR CONTOURS AT 10 FOOT INTERVALS
44444114441rx
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11111111111111141111111111114‘111 4 111 '.. • .;A .
AREA 4 «.•..•.»..... HOLECENCE SEDIMENT THICKNESS CONTOUR (DILL
). 42 ASSUMED HOLOCENE SEDIMENT THICKNESS
` POTENTIAL HARD BOTTOM RECOVERY AREA
AREA 3 ! Area 1-Area behind dike(Alt. 1 = 9 ac.;Alt 2. = 17 ac.)
41
Area 2-Nearshore area between-10 and-30 MLLW
a='zk 5 Y^. 'N, ! �''4.t. (Alt. 1 =51 ac.;Alt.2 =41 ac.)
10` .. , Area 3-Nearshore area between-20 and-30 MLLW(11 ac.)
., ... •.•. -..oi`•.,. AREA J Area 4-Bunker Point Reef-existing kelp bed(173 ac.)
ss. • •. . Area 5-Bunker Pt.To Whites Pt.-existing kelp bed(220 ac.)1
1000 ..500 0 1000 2000EI0 i'' • `r
\
SCALE. 1"._1000' .
NOTES, a.m.is WAN LOWS LOY VOTER
1. HOLOCENE SEDIMENT THICKNESS OVER BEDROCK 0
a Lti
(CONTOUR INTERVAL 5 FT) . SOURCE' R.F. DILL ET AL, 1995Rvls=
AMOT
2. CORPS' 07-95 HYDRO SURVEY CONTOURS AT 10 FT INTERVALS. LOS ONCEI
ES
CAPS OF CNOINEERS
3. LAND CONTOURS FROM 08-95 AERIAL SURVEY AT 10 FT INTERVALS. RANCHO PALOS VERDES FEASIBILITY STUDY
SUPPLIED BY THE CITY OF RPV. ... LOS ANGELES COUNTY. CALIFORNIA
' SEDIMENT THICKNESS
1 ...0 ...m... aresrrr.. . .• MT
N.
......:. ... .... ... ......:..... .. ....:,. ., :.. .. ................ � '.r... .. ... .OL5IRICT FM N0. .....EI
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canopy that might preclude access of dredging equipment, and was, therefore, not considered.)
I•
In this following impact analysis it is expected that, once exposed, this hard bottom surface would
be re-colonized by marine plant and animal life like those occurring upcoast in the unaffected areas
of the peninsula(e.g.,Palos Verdes Point reference site - see discussion in Section 4.3.2). (Note that
a detailed discussion of the negative effects of sedimentation on kelp forest appear in Foster and
Schiel [1985:10].)
(It should be noted that the sediment thickness(as per Dill and Nordall 1995 depicted in Fig. 5.1) is
less than 5 feet for most of the nearshore area. However, Sadd and Davis (1997) (Appendix B)
reported that sediment is, in general, less than a meter(3.3 ft.)thick as far out as the 25-foot isobath.)
Benefits of Reduced Turbidity. The near-constant turbidity plume and its associated water column
impacts on existing kelp beds are presumed to extend at least to the 30-foot isobath from Portuguese
Bend to Whites Point. This area of impact includes the 173 acres of reef area at Bunker Point
(identified as "Area 4" on Fig. 5.1) which is largely sediment free, and the nearshore area from
Bunker Point to Whites Point(approximately 230 acres) depicted as Area 5 on Figure 5.1.
The impacts of turbidity(i.e., decreased light penetration) on marine plants, especially giant kelp, is
discussed in detail in Forster and Schiel (1985:12). (Also see Stephens et al. 1994:1222.). Since all
kelp and marine plants of the kelp forest start life on hard bottom substrate, sufficient light must
penetrate to the bottom substrate to permit photosynthesis in gametophytes attached on the bottom. •
Luning(1981) suggest that kelp plants do not grow where irradiance is reduced to 1% of that at the
surface (known as the euphotic depth). Surveys to document the extent of light penetration in the
water column were performed for the Reconnaissance Report for the Rancho Palos Verdes area.
These surveys document that the sediment plume does, at times, inhibit 1% irradiance from reaching
some of the bottom substrate that could support kelp (Cee Stephens 1990:C-2-18 and Stephens
1990:Appendix A,Figure A-1). Stephens(1990:C-2-18) concluded that"[d]uring periods of strong
plume development, kelp growth is certainly inhibited or completely suppressed".
In addition to limiting the depth at which kelp plants can grow, less than optimal light levels have
been shown to reduce growth rates, fertility, and survivability of gametophytes of established plants
(Dean and Deysher 1983; Luning 1980; Luning and Neushul 1978). All of these factors affect the
quality of kelp forest habitat. (Also see further discussion of turbidity impacts to the marine
biological community of the Study Area in Pondella et al. 1996:56-58.)
The action alternatives are designed to contain all landslide-generate turbidity; the water clarity is
expected to be immediately improved to pre-landslide conditions. As such, the improvement in
habitat quality of some 400 acres of existing kelp beds(Area 4+Area 5)is expected to be immediate.
Evidence to support the expected benefits. There are several facts supporting the prediction that
5-4 1110
• giant kelp in the area may be restored as expected. First, sediment covering the nearshore area is
unconsolidated material and no cementation or unusual compaction was reported from sediment
surveys(Sadd and Davis 1997:9). Secondly, several studies report that wave-generated currents are
actively eroding landslide-generated sediment that is deposited into Portuguese Bend from the
nearshore to offshore and downcoast areas(Drake et al. 1994:8;Kayen et al. 1994:8; Sadd and Davis
1997:12). Thirdly, a 744-foot long tiered gabion structure constructed in 1988 (and later lengthened
to 2100 feet)by the City of Rancho Palos Verdes in Portuguese Bend was reported to have reduced
sedimentation and turbidity in the immediate nearshore area and resulted in the development of a lone
kelp stand in the area(see USACE 1992:15 and Stephens 1990: page C-2-18). Also, as mentioned
in section 4.3.2, a few clumps of kelp have appeared in Portuguese Bend this year which indicates
that kelp was likely an important component of the Bend's marine environment. Finally, giant kelp
forest occurs in Portuguese Bend in areas when sedimentation is relatively thin and/or where hard
bottom is repeatedly uncovered (see Appendix A:15 and 55).
Contaminated Sediment - Offshore. As discussed in Section 4.6.1, an effluent-affected
contaminated mound occurs about 160-200 ft. offshore the peninsula. It has been speculated that
sediment from the Portuguese Bend landslide covers portions of the effluent-effected mound and
thereby prevents the release of contaminants from the mound(see USFWS letter dated June 13, 1995
in Appendix K).
By use of predictive models, Drake et al. (1994:45) contend that portions of Portuguese Bend
landslide sediment reside on the inner and middle continental shelf(<60 meters) and is being moved
by currents to deeper waters in the northwest. They contend that sediment is contributing to covering
up the northwestern portion of the effluent-affected contaminated mound. Their analysis predicts
that, assuming sedimentation rates from the landslide will decrease (when measures to control the
landslide significantly halt erosion), the contaminated mound will erode in the northwestern part
(Drake et al 1994:49). They further make predictions of the effect of biological mixing and
desorption of DDT and predict what future background contaminant levels might be in the next
century.
The Corps' sediment budget analysis indicate that most of the sediment remains in the nearshore and
a considerable amount moves downcoast and offshore. No estimate is given as to how much
sediment moves offshore, let alone an estimate as to what amount might be contributing to the
covering of the effluent-affected mound (see Coastal Engineering Appendix, Plate 3). The Corps
specifically requested the Environmental Protection's Agency's (EPA) opinion of the impact that
containment of Portuguese Bend landslide-generated sediment might have on the effluent-affected
mound offshore. EPA feels that sediment from the landslide makes no significant contribution to the
stabilization of the offshore mound (EPA, 1998 per corn).
As such, the containment of landslide-generated sediment is considered to have no effect on the
effluent-affected mound on the continental shelf.
4110 5-5
Contaminated Sediment-Nearshore. As previously mentioned in Section 4.5.2, cadmium, nickel,
and DDE(a derivative ofDDT)were detected in nearshore sediment. The most likely source of this
contamination is, of course, the contaminated mound further offshore the Palos Verdes Peninsula.
(It bears repeating [from Section 4.6.2] that the contamination levels found in the nearshore cores
taken in Portuguese Bend are similar to"background" contaminated sediment levels in Santa Monica
Bay [see Sadd and Davis 1997:25] and several times less than the levels found in and near the
effluent-affected contaminated mound offshore the Peninsula.)
The fact that heavy metals tended to be in the upper layers of sediment and DDE occurred in all layers
(but more common in lower layers in the eastern part of the study area)lend support to the thought
that the nearshore sediment column is being mixed by physical and biological processes (Sadd and
Davis 1997:22). There is no reason to believe that Portuguese Bend sediment is"capping" nearshore
contaminants or that containment of landslide-generated sediment would make the contaminates
found in nearshore sediment any more biologically available than without containment of landslide-
generated sediment (i.e., without the project).
Dredging Impacts. As previously mentioned, alternative la and 2a involve dredging sediment off
of existing hard rock reef(see section 3.2 and 3.4). Alternative la involves dredging some 462,000
cu. yds. and Alternative 2a involves dredging some 422,000 cu. yds. of material. Also, all alternatives
involve dredging behind the dike (350,000 cu. yds. every 20 years for Alternatives 1 or la and
680,000 cu. yds. once during the life of the project for Alternatives 2 or 2a). •
The impacts of dredging on marine biological resources are discussed at length in LaSalle et al.
(1991). That review provides summaries on much of the literature concerning impacts of the physical
and chemical alterations associated with dredging on shellfish, fish, benthic organisms, seabirds, and
marine mammals. That report describes, in detail, specific environmental consequences - such as,
suspended sediments, sedimentation, dissolved oxygen reduction, and entrainment-which are caused
by dredging. That report is hereby incorporated by reference as per 40 CFR 1502.21.
The expected effects of dredging on the marine environment of the project area are discussed in detail
in Appendix E(404(b)(1) evaluation- sections II.d, II.e, IIIc-g). In summary, the adverse impacts
of dredging are largely caused by the resuspension of sediment and the increased turbidity in the water
column when compared to background levels. Dredging behind the dike is expected to have no
impact on the marine environment as dredge-generated turbidity turbidity will be confined within the
dike.
The dredging to uncover shallow hard rock areas will be of small quantities and turbidity impacts are
expected to be localized and short term. The beneficial impacts of removing sediment from hard
rock reef and allowing it to be recolonized by marine plants and animals are expected to be
significant. The dredged material is expected to be suitable for disposal into the LA-2 ocean disposal
site, and no adverse impacts are expected to be associated with this disposal of sediment. Therefore,
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• no significant adverse impacts to the marine environment from dredging and disposing of material in
the project area are expected.
5.1.2 Without Project(i.e., No Action ) Condition Assumptions
The impacts of the proposed alternatives were evaluated relative to existing baseline conditions (see
Section 4)and conditions that are assumed to continue to occur in the future without implementation
of the action alternatives. In the impact analysis, the following future without project conditions are
assumed to occur over the next 50 years:
► Sedimentation into the marine environment at Portuguese Bend will continue at the estimated
average annual rate of 146,000 cu. yds. The rate of the Portuguese Bend Landslide is expected
to continue at 7.6 ft./yr. throughout the life of the project.
► Over the next 50 years,the landslide is expected to contribute 89,000 cu. yds of sand size materials
per year and 58,000 cu. yds of clay and silt size materials offshore per year. This sedimentation
and the high downcoast turbidity will continue to affect marine water quality.
► The City of Rancho Palos Verdes will continue its efforts to halt movement in the Portuguese
Bend Landslide Area. The efforts include the current stabilization measures of ground and surface
water management, and the grading and redistribution of the land mass.
► The current building moratorium will remain in effect for the Portuguese Bend landslide area.
• • Current land uses in the Study Area will not significantly change.
5.2 Physical Environment
5.2.1 Geology
Significance Criteria. Based on the following significance criteria, the action alternatives would
have significant adverse impacts on the geology of the study area if it would:
► Substantially alter topography beyond that which results from natural erosion and deposition
► Trigger or accelerate the Portuguese Bend landslide through construction or construction related
disturbances.
5.2.1.1 Impacts and Mitigation Measures.
Topography. Neither alternative would have any significant impact on the existing topography of
the area. Both proposed dikes are largely offshore; only about .5 acres(100'x 200') of nearshore area
will be disturbed by the dike's connection to the nearshore (see Fig 3.la and 3.2a, stations 0+00-
2+31).
• 5-7
Landslide/slope stability. The offshore dike(Alternative 2) may be beyond the toe of the seaward
subslide of the Portuguese Bend Landslide. The nearshore dike may be within the toe of the existing
landslide, however,the proposed structure is not expected to have any accelerating effect on the slide
or movement of the land mass. (See discussion in the Main Report, Chapters 3 and 4.)
5.2.2 Marine Currents and Tides
Significance Criteria. Based on the following significance criteria, the action alternatives would
have significant adverse impacts on marine currents and tides of the study area if it would:
► Substantially alter ocean currents(longshore or cross-shore) or tide/water levels in the study area
► Result in substantial accretion or shoreline erosion of adjacent beaches.
5.2.2.1 Impacts and Mitigation Measures
Shoreline erosion or accretion. Scour is expected to occur immediately downcoast of the dike.
The scour is expected to have a minor impact on the downcoast beach as it is composed mostly of
cobbles. No other local scour is expected to occur(see Coastal Engineer Appendix, section 7.6.1).
5.2.3 Air Quality
Significance Criteria. Air qualityimpacts due to the proposed construction activities fall under both •
i� P P P
Federal and State regulation. Determination of compliance with these regulations necessitates
estimation of criteria pollutants emissions(i.e., oxides of nitrogen(NO„), reactive organic compounds
(ROC), oxides of sulfur (SO,), PM-10, and Carbon Monoxide (CO)). Although ozone is also a
criteria pollutant, emissions do riot need to be estimated because it is not emitted directly, but formed
through the interaction of NOR, ROC, and sunlight.
The Clean Air Act (CAA) as amended in 1990, specifies in Section 176(a) that no department,
agency, or instrumentality of the Federal Government will engage in, support in any way, or provide
financial assistance for, license or permit, or approve, any activity which does not conform to an
implementation plan after it has been approved or promulgated under section 110 of this title.
"Conformity" is defined in Section 176 (c) of the CAA as conformity to the State Implementation
Plan's purpose of eliminating or reducing the severity and number of violations of the National
Ambient Air Quality Standards and achieving expeditious attainment of such standards, and that the
activities will not:
1. Cause or contribute to any new violation of any standard in any area; or
2. Increase the frequency or severity of any existing violation of any standard in any area; or
3. Delay timely attainment of any standard or any required interim emission reductions or other
milestones in any area.
5-8 •
Criteria for compliance with the above provisions are specified in 40 CFR 93.153(b). This section
lists de minimis levels for which exceedance would necessitate a formal conformity determination.
As mentioned in Section 4.1.3, the SCAB (South Coast Air Basin) is in "extreme" non-attainment
for the NAAQS for 03, "serious" non-attainment for the NAAQS for CO and PM10, non-attainment
for the NAAQS for NO2, and in attainment of the NAAQS for SO2. The Air Resources Board (ARB)
also designates areas of the state as either in attainment or non-attainment of the CAAQS. An area
is in non-attainment if the CAAQS has been exceeded more than once in three years. At the present
time,the SCAB is in"severe" non-attainment for the CAAQS for 03, NO2, and CO, non-attainment
for the CAAQS for PM10i and in attainment of the CAAQS for SO2 (SCAQMD 1994).
Criteria to determine the significance of air quality impacts are based on federal, state, and local air
pollution standards and regulations. Impacts are considered significant if total project emissions:
► increase ambient pollutant levels from below to above the NAAQS or CAAQS;
► substantially contribute to an existing or projected air quality standard violation
► are inconsistent with Air Quality Management Plan(AQMP)
► exceed the following thresholds that the SCAQMD defines as significant under CEQA as shown
below.
• SCAQMD Significance Thresholds
Construction Alternative .Q NOz LM ROC SQX
Operation(lbs/day) 550 55 150 55 150
Construction(Daily) (lbs/day) 550 100 150 75 150
Construction(Quarterly) 24.75 2.5 6.75 2.5 6.75
(Tons/Quarter)
Sourcq: SCAQMD 1993
5.2.3.1 Impacts and Mitigation Measures
A detailed air quality analysis of emissions expected to be generated from the action alternatives for
initial construction and future maintenance is provided in Appendix G. The projected emissions were
calculated as recommended in the SCAQMD handbook(SCAQMD 1993).
The proposed construction of a nearshore dike is, in general, expected to generate less than
significant SCAQMD threshold levels for most pollutants. Fugitive dust is expected to be above
significant thresholds unless impacts are mitigated by watering the work site at least twice a day. This
measure is expected to reduce dust levels to below significant thresholds identified by SCAQMD (see
•
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Appendix G, Table 1).
Since rock for dike construction could be obtained from an offshore source(i.e., barged from Catalina
Island) or from a remote mainland source (trucking rock from Riverside was used as a worst case
scenario), both sources were analyzed for air quality impacts. Barging rock is not expected to
generate pollutants above significant thresholds, but tug boat NOx emissions contribute a large
percentage of daily totals. (Note this is consistent with a press release by SCAQMD 1998.) Trucking
rock from 75 miles away, however, is expected to generate NOx levels above significant thresholds
(see Appendix G, Table 1). The daily emissions of NOx can be lowered to below threshold levels by
extending the construction period another six months (i.e., to 2 years). This would have the effect
of reducing the number of trucks hauling rock per day and, thereby, the daily total NOx emissions.
Emissions from activities associated with future maintenance are expected to be below SCAQMD
thresholds for all pollutants except fugitive dust (see Appendix G, Tables 3 and 4). Dust impacts
could be mitigated to below significant levels by watering the site twice daily, as recommended for
initial construction.
5.2.4 Water Resources and Water Quality
Significance Criteria. Based on the following significance criteria, the action alternatives would
have significant adverse impacts on the water resources or water quality of the study area if it would:
1. •
Substantially degrade the local water quality
Substantial change the rate and amount of surface runoff or change the amount of water in any
body of water.
5.2.4.1 Impacts and Mitigation Measures
Neither alternative will affect surface runoff nor any terrestrial body of water.
Water Quality Within the Dike. As the area behind the dike gradually fills with landslide material,
the gn2lity 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 (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 (Class III). During the Preconstruction Engineering and
Design(PED)phase a more quantitative evaluation of the movement and exchange of water behind
•
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11111 the dike is proposed to further verify this assessment. (Note D.O. levels that constitute anoxia,
hypoxia, and biological stresses cited above 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 the 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(Class V).
5.3 Biological Resources
Significance Criteria. Based on the following significance criteria, the action alternatives would
have significant adverse impacts on the biological resources of the study area if it would result in:
► substantial loss of natural vegetation, either marine and terrestrial.
► substantial loss of species diversity.
► disruption or interference with heavily used fish or wildlife migration corridors or routes.
► the net degradation or loss of a sensitive habitat (e.g., kelp beds).
► loss or disturbance of individual listed Federal or State Threatened or Endangered species.
► substantial loss of individuals of a Federal Candidate species.
•
5.3.1 Coastal Zone Resources
5.3.1.1 Impacts and Mitigation Measures
Vegetation. Land access to the dike construction site would be via the haul road described in
section 3.1. As mentioned in section 3.1, the improvement of the existing road and extending it to
accommodate the hauling of numerous rock-laden dump trucks would require the disturbance of
about 25,000 - 30,000 sq-ft and the loss of 0.6-0.7 acres of mostly ruderal, exotic grassland
vegetation. The impact of removing less than an acre of this vegetation to expand and extend the
existing road is expected to be insignificant (Class III).
The dike's attachment to the shoreline involves only about 0.5 acres (100'x 200') of nearshore area
which will be disturbed by the dike's connection to the nearshore (see Fig 3.1a and 3.2a, stations
0+00-2+31). That area of shoreline is highly disturbed by the moving land mass and no significant
adverse impacts to shoreline vegetation is expected to result from dike construction. The proposed
action alternatives,therefore,will not significantly affect onshore vegetation. The proposed dikes are
not expected to stabilize the Portuguese Bend landslide nor slow its current rate of movement. The
existing onshore vegetation is expected to continue to be disturbed by the ongoing landslide.
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Wildlife. As with coastal vegetation, no coastal or terrestrial wildlife are expected to be significantly
effected by the action alternatives. The proposed dikes will not stabilize the Portuguese Bend •
landslide nor slow its current rate of movement. The quality of the existing coastal/terrestrial wildlife
habitat will not be affected by the action alternatives. As such, no coastal or terrestrial wildlife is
expected to be negatively impacted by the action alternatives.
Bradley and Bradley (1993) speculated that the return of kelp to portions of the Palos Verdes
Peninsula resulted in an increase in winter shorebird densities. The return of kelp to the peninsula
resulted in increased kelp windthrow along the shore; Bradley and Bradley (1993) presumed the
increased windthrow provides an increased food base for foraging shorebirds (e.g., spotted sandpiper,
wandering tattler, whimbrel, and the black and ruddy turnstones) that led to the increased winter
shorebird density they observed. As such, a beneficial impact to wintering shorebirds might be
expected from the action alternatives.
5.3.2 Marine Biological Resources
The following discussion is an analysis of the potential positive and negative impacts of the action
alternatives on the marine biological resources in the study area. The impacts are evaluated relative
to existing baseline conditions and without project assumptions (see Section 5.1.2).
Corps regulations (EC 1105-2-210)require a quantitative evaluation of habitats restored under the
various alternatives for environmental restoration feasibility studies. A quantitative habitat valuation •:
is presented in Appendix C, and the reader should review that Appendix for a quantitative analysis
of the expected net gain of habitat value from the action alternatives.
5.3.2.1 Vegetation -Impacts and Mitigation Measures
Marine Vegetation Within the Dike. As mentioned previously, the area behind the dike will
gradually be filled with landslide material. All existing marine vegetation(i.e., the predominant green
algal mats common to the intertidal portions of the study area- see Section 4.3.2.1)within the dike's
footprint are expected to be smothered by sediment. The basalt outcrop of Inspiration Point provides
hard rock surface for intertidal marine plants such as, feather boa kelp (Egregia menziesi); all marine
vegetation in that portion of the outcrop within the dike(about 200 feet in length) is expected be lost.
Despite the heavy sediment deposit some giant kelp exist on a few exposed hard surfaces in
Portuguese Bend - especially in the southern end of the Bend. As previously mentioned (section
4.3.2)a few scatered clumps of kelp have recently appeared in the Bend probably as a result of very
favorable(to kelp)La Nina conditions of this year. During most years, however, there are no longer
any significant kelp beds in Portuguese Bend. Subtidal surveys performed for this study detected
giant kelp, mostly beyond-30 MLLW(see Appendix A, pg. 15), in that portion of the Bend. Neither
5-12 •
• dike alternative(especially the nearshore dike) is likely to impact the few existing kelp stands of the
area as the dikes are within the -20'MLLW contour.
The loss of marine vegetation is expected to be adverse but not significant(Class III). Green algal
vegetation or the intertidal vegetation is expected to be smothered by landslide sediment; a net gain
of a sensitive marine resource (i.e., kelp forest) is expected to result from containing landslide
sediment within the dike (see following discussion).
Marine Vegetation Outside of the Dike. The proposed dikes are designed and intended to contain
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 landslide material; sediment covering
hard bottom down to the -30 ft. MLLW contour is expected to be uncovered by natural processes
(Alternatives 1 or 2) (see discussion on pages 5-1 and 5-2) or by mechanically dredging sediment
(Alternatives la or 2a). It is estimated that some 50-60 acres (Alternative 2 or 1, respectively) of
hard rock will be re-exposed and re-colonized by marine vegetation, especially giant kelp and its
associated understory vegetation(see Table 7 in Section 5.1.1).
Under both action alternatives approximately 173 acres of existing kelp forests at Bunker Point and
230 nearshore acres from Bunker Point to Whites Point are expected to benefit from eliminating the
almost constant turbidity that impacts these beds. As such, significant beneficial impacts to marine
vegetation are expected (Class V).
•
Also, the oceanside of the dike, itself, will create intertidal and subtidal hard rock habitat. Intertidal
and subtidal plants are expected to colonize the structure immediately after its construction.
5.3.2.2 Invertebrate Animals - Impacts and Mitigation Measures
Invertebrate Animals Within the Dike. As mentioned previously, the area behind the dike will
gradually be filled with landslide material. All existing invertebrate animals (i.e., the predominant soft
bottom species [e.g., sea pens, sand stars, brittle stars, tube worms - see Section 4.3.2.2])within the
dike's footprint are expected to be smothered by sediment. The basalt outcrop of Inspiration Point
provides some hard rock surface for rocky intertidal/subtidal invertebrates (e.g., gorgonian, sea
urchins, mussels, and sea anemone);all invertebrate animals in that portion of the outcrop within the
dike (about 200 feet in length) are expected be lost.
As mentioned for marine vegetation, despite the heavy sediment deposit some giant kelp exist on a
few exposed hard surfaces in Portuguese Bend-especially in the southern end of the Bend. Subtidal
surveys performed for this study detected giant kelp, mostly beyond -30 ft. MLLW(see Appendix
A, pg. 15), in that portion of the Bend. Some kelp associated animals (e.g., gastropods, and the
elbow crab)were also observed. Neither dike alternative (especially the nearshore dike) is likely to
impact the few existing kelp stands of the area as the dikes are within the -20'MLLW contour.
•
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The loss of intertidal and subtidal invertebrate animals in the dike is expected to be adverse but not
significant (Class III), as these animals are not a sensitive resource, and a net significant gain of a
sensitive marine resource(i.e., kelp forest and its associated diverse animal community) is expected
(see following discussion).
Marine Vegetation Outside of the Dike. The proposed dikes are designed and intended to contain
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 the erosion of landslide material; sediment covering
hard bottom down to the -30 ft. MLLW contour is expected to be uncovered by natural processes
(Alternatives 1 or 2) (see discussion on pages 5-1 and 5-2) or by mechanically dredging sediment
(Alternatives la or 2a). It is estimated that approximately 50-60 acres (depending on the action
alternative) of hard rock will be re-exposed and re-colonized by marine vegetation and animals,
especially giant kelp and its associated biological community of plants and animals.
Under both action alternatives approximately 173 acres of existing kelp forests at Bunker Point and
230 nearshore acres from Bunker Point to Whites Point are expected to be benefited by eliminating
the almost constant turbidity that impacts these beds. As such, significant beneficial impacts to
invertebrate animals associated with kelp beds and hard rock substrate are expected (Class V).
Also,the oceanside of the dike, itself, will create intertidal and subtidal hard rock habitat. Intertidal
and subtidal invertebrate animals are expected to colonize the structure immediately after its
construction.
5.3.2.3 Marine Fishes -Impacts and Mitigation Measures
Marine Fishes Within the Dike. As mentioned previously, the area behind the dike will gradually
be filled with landslide material. As mentioned in section 4.3.2.3, the fish community of Portuguese
Bend is a depauparate fish community, especially when compared to unimpacted areas upcoast(e.g.,
Rocky Point). Nevertheless, all fishes trapped within the dike are expected to eventually die as a
result of the deteriorating water quality.
The loss of this depauparate fish community within the dike is expected to be adverse but not
significant (Class III), as these fish are not a sensitive resource, and a significant net gain of a
sensitive marine resource(i.e., kelp forest and its associated diverse fishes) is expected (see following
discussion).
Marine Fishes Outside of the Dike. The proposed dikes are designed to contain 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 the erosion of landslide material; sediment covering hard bottom
outside of the dike down to the -30 ft. MLLW contour is expected to be uncovered by natural
processes (Alternatives 1 or 2) (see discussion on pages 5-1 and 5-2) or by mechanically dredging
•
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• sediment(Alternatives la or 2a). As discussed above, it is estimated that some 50-60 acres of hard
rock will be re-exposed and re-colonized by marine vegetation and fishes, especially by giant kelp and
its associated biological community of plants and fishes.
Under both action alternatives approximately 173 acres of existing kelp forests at Bunker Point and
230 nearshore acres from Bunker Point to Whites Point are expected to be benefited by eliminating
the almost constant turbidity that impacts these kelp beds and the water column. As such, significant
beneficial impacts to marine fishes are expected from restoring important marine fish habitat(i.e., the
kelp forest) and by improving the quality of existing kelp areas through elimination of the near
constant turbidity caused by eroding landslide material (Class V).
5.3.2.4 Essential Fish Habitat
As mentioned above (section 5.3.2.3), many native marine fish are expected to benefit from
eliminating the negative impacts that the landslide-generated sediment has had on covering hard rock
reef and the negative impacts that the near-constant turbidity plume has on existing kelp beds
downcoast. Several"managed species" (i.e., species covered by the three fishery management plans
(FMPs)under the auspices of the Pacific Fishery Management Council [NMFS 1998:Table 1]) occur
in the project area. Also, many other native marine fish in the study area undoubtedly serve as prey
for many of the managed species. Eliminating the negative impacts of the landslide-genetated
sediment and turbidity from the nearshore marine environment is expected, therefore, to improve the
• habitat quality of"managed" fish species and fish that may serve as prey for managed species. As
such, the Corps has determined that the proposed restoration plan is expected to have a significant
net beneficial impact on Essential Fish Habitat.
5.3.3 Threatened and Endangered Species
Of the listed threatened or endangered species reasonably expected to occur in the study area(see
section 4.3.3), only the least tern and the brown pelican may be affected by the action alternatives.
A more detailed analysis of the impacts to threatened and endangered species appears in the
Biological Assessment (Appendix J).
5.3.3.1 Impacts and Mitigation Measures
Since the proposed dike will be offshore, the dike, itself, is not expected to affect any terrestrial
resources. The dike will not alter the existing Portuguese Bend Landslide and it is estimated that the
current rate of land movement will continue, unchanged throughout the life of the project. (In fact,
the proposed maintenance dredging during the project's 50-year life is necessary to remove debris
expected to accumulate behind the dike as a result of the continued movement.) Whatever land
movement that currently occurs and its affects on existing terrestrial vegetation will continue and not
be affected by the offshore dike.
•
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The grassland area that will be used for hauling rock material to the construction sight is not known
to have any threatened or endangered species (see City of RPV 1999:sections 2.3 and 2.4). As such,
no impacts to any terrestrial or endangered species are expected to occur. The NCCP Subarea Plan
Phase I Summary Report, however, does identify the area as a possible"reserve area" and an area
with"moderate"restoration potential (City of RPV 1999: sections 2.5 and 2.8). The proposed haul
road are not expected to alter that possible usage.
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 action alternatives.
(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. Jacques et al. (1996:45)estimated that 65% of all pelicans in southern California
roosted on artificial structures(i.e., groins,jetties, and breakwaters) associated with harbors. (The
breakwaters of Los Angeles consistently support hundreds of roosting birds during the day.) The
proposed dike is expected to serve as a day roost for brown pelicans. (Since it will be attached to
the shoreline-it probably will not be used as a night roost.) The creation of brown pelican roosting
habitat is expected to be a beneficial impact.
Containing sediment behind the proposed dike is expected to have tic, affect on the effluent-affected
offshore mound. 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 dike. (Also see discussion in Section
5.6.)
Impacts to the endangered species California brown pelican and Califonia least tern are expected to
be beneficial (Class V).
5.4 Land Use and Recreation
Significance Criteria. Based on the following significance criteria, the action alternatives would
have significant adverse impacts on existing land usage or recreation activities of the study area if it
would:
► Result in long-term disturbances that would diminish or change the quality and character of a
particular land use.
► Result in permanent preclusion of a permitted use or a particular land use
► Result in the long-term loss or degradation of the recreational value of a major recreational activity
5-16 •
• 5.4.1 Impacts and Mitigation Measures
Land Use. The action alternatives (the proposed offshore and nearshore dikes) are not expected to
impact any existing or future land uses planned for the area(Class IV). The action alternatives are
not expected to affect any existing or future land uses, i.e., the existing building moratorium, any
current or future open-space or residential use zoning, any existing or future residential or commercial
development, or future plans to establish an NCCP preserve in the study area.
No existing residential areas are expected to be affected by any construction related activities (e.g.,
truck/vehicle traffic or construction or traffic noise) because construction-related traffic will be via
roads away from residential areas.
Recreation. The action alternatives are not expected to affect any land based 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 (Class III) as these are minor usages by local residents.
(There is no public access to the beach).
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 action alternatives (Class V).
5.5 Aesthetics
Significance Criteria. Based on the following significance criteria, the action alternatives would
have significant adverse impacts on aesthetic resources of the study area if it would:
► Permanently change important scenic characteristics of a landscape that could be viewed by a large
number of viewers
► Impair or obstruct views from public gathering places of scenic resources identified in Federal,
State, or local plans.
5.5.1 Impacts and Mitigation Measures
The proposed dikes of the action alternatives would be a significant, hard structure constructed along
the coast. As designed,the offshore dike would be 18' at its widest section and as much as 28' above
MLLW at its highest point;the nearshore dike is 14' at its widest section and 14' above MLLW at its
highest point. Despite its size, from land the dike would be visible to mainly local residents of
1111 Portuguese Bend yacht club area. From Rancho Palos Verdes Drive South Portuguese Bend is only
5-17
visible at a few brief locations. When traveling west on Rancho Palos Verdes Drive South, •
Portuguese Bend cove is visible for only about a 0.2 mile stretch just past the Schooner Drive
intersection and a 0.2 mile stretch past Portuguese Canyon. There are no locations, however, where
the public can pull over on Rancho Palos Verdes Drive South and get an unrestricted view of
Portuguese Bend.
The structure would also be visible from Inspiration Point, but there is no public access to Inspiration
Point. As mentioned in Section 4.4,Portuguese Point and Smugglers Cove receive remarkable usage
from swimmers and sunbathers, despite its awkward access; these recreationists, however, rarely
venture around Inspiration Point to Portuguese Bend. From offshore, the structure would be visible
to any vessels or boats traveling through the area.
The impact to the aesthetic quality of the area is considered adverse, but not significant (as per the
above significance criteria) (Class III), because it would not impair the view of the general public.
The adverse aesthetic impact of the dike to local residents, however, is expected to be significant and
not mitigable.
Significant benefits to the aesthetic quality of a large number of ocean viewers could be realized as
the structure eliminates the large turbidity plume that is visible from several shoreline locations (Class
zn
V).
5.6 Sediment Chemical Contamination �..
Significance Criteria. Based on the following significance criteria, the action alternatives would
have significant adverse impacts on sediment quality of the study area if it would:
► Result in a substantial increase, above existing background levels, in the chemical contamination
of sediment.
► Result in the uncovering of buried contaminated sediment, thereby increasing their bio-availability
to marine plants or animals.
5.6.1 Impacts and Mitigation Measures
Impacts to the effluent-affected mound offshore. As discussed in Section 5.1.1, some have
speculated that sediment from the Portuguese Bend landslide contributes a significant covering of
the effluent-affected mound offshore the Palos Verdes Peninsula.
EPA staff involved in the Palos Verdes investigation, however, feel that sediment from the landslide
makes no significant contribution to the stabilization of the offshore mound (EPA, per corn 1998).
As such,the containment of landslide-generated sediment is considered to have no affect on the bio-
5-18 •
• availability of contaminants from the effluent-affected mound (Class IV).
Impacts to Nearshore Sediment. Impacts to nearshore sediment were discussed earlier(Section
5.1). As mentioned, the detectable contaminant levels in sediment are similar to the background
levels found throughout Santa Monica Bay. These detectable levels of DDE, and heavy metals
appear in upper, middle, and lower layers, and there is no evidence that Portuguese Bend sediment
serves as a natural cap of nearshore sediment. Even without the proposed action alternatives,
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 Davis 1997:12 & 22;
Drake et al. 1994:8; Kayen et al. 1994:8). The action alternatives, therefore, are not expected to
affect the bio-availability of the low level of contaminants in the nearshore sediment any differently
than under without project conditions (Class IV).
5.7 Cultural Resources
Significance Criteria. In accordance with the national Historic Preservation Act of 1996, and the
Advisory Council Regulations (36 CFR 800.9), Criteria of Effects and Adverse Effect, impacts to
cultural resources are considered significant if one or more of the following conditions would result
from implementation of the action alternatives:
• (a) An undertaking has an effect on a historic property when the undertaking may alter
characteristics of the property that may qualify the property for inclusion in the National Register.
For the purpose of determining effect, alterations to features of a property's location, setting, or use
may be relevant depending on a property's significant characteristics and should be considered.
(b) An undertaking is considered to have an adverse effect when the effect on a historic property
may diminish the integrity of the property's location, design, setting, materials, workmanship, feeling,
or association. Adverse effects on historic properties include, but are not limited to:
(1) Physical destruction, damage, or alteration of all or part of the property
(2) Isolation of the property from or alteration of the character of the property's setting
when that character contributes to the property's qualification for the national register
(3) Introduction of visual, audible, or atmospheric elements that are out of character with
the property or alter its setting
(4) Neglect of a property resulting in its deterioration or destruction
(5) Transfer, lease, or sale of the property
110
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The National Park Service USDI(No Date)recognizes different types of values embodied in districts,
sites, buildings, structures, and objects. These values fall into the following categories: •.
(a) Associative Value (Criterion A and B): Properties significant for their association or linkage
to events (Criteria A) or persons (Criteria B) important to the past.
(b) Design or Constructive Value (Criterion C): Properties significant as representative of the
manmade expression of culture or technology.
(c) Information Value (Criterion D): Properties significant for their ability to yield important
information about prehistory or history.
5.7.1 Impacts and Mitigation Measures
Application of the Criteria of Effect and Adverse Effect per 36 CFR 800.5 cannot be completed until
any identified archeological site within the APE has been evaluated for eligibility regarding the NRNP.
Cultural resources will be avoided, if possible. Sites that cannot be avoided will be evaluated. Data
recovery (mitigation), if necessary, will be implemented prior to construction.
The potential exists for National Register eligible sites being located within the Project APE.
A detailed underwater archeological survey will be conducted of the project area during the
•
Preconstruction Engineering and Design (PED) phase to determine if any significant
cultural/archeological resources exist and identified sites would be evaluated regarding eligibility for
listing in the National Register of Historic Places (IVRHPP).
5.8 No Action Alternative
Under the No Action alternative none of the adverse or beneficial impacts associated with the action
alternatives would occur. Adverse impacts to nearshore marine plants and animals from dike
constructions(including operation and maintenance) and eventual silting in that is expected to occur
behind the proposed dikes would not occur. The adverse impact to the water quality of ocean water
trapped behind the dike would not occur. The adverse aesthetic impact caused by the dike would not
occur.
None of the expected beneficial impacts would be realized under this alternative. Sedimentation and
its associated turbidity would continue; the current adverse impacts of sedimentation and turbidity
to water quality,marine plants and animals would continue. No hard rock habitat would become re-
exposed and re-colonized by marine plants or animals. The existing kelp beds and rocky subtidal
areas downcoast would continue to be adversely affected by the extensive turbidity plume from
Portuguese Bend.
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• 5.9 Cumulative Impacts
5.9.1 Projects Considered in Cumulative Analysis
This section addresses potential "cumulative impacts," that is, environmental effects associated with
the proposed action that could be compounded or increased as a result of combined effects of past,
present and reasonably foreseeable projects. Cumulative effects of other projects are relevant to this
analysis in terms of those types of impacts that could occur during the same time frame and affect the
same environmental conditions as the impacts associated with the proposed action. Projects that are
distant from the subject Study Area or which would have no interactive effects relative to the
proposed action are not addressed. Table 8 lists the other projects that are currently underway or in
the planning stage that are relevant to this cumulative impact analysis.
The Cumulative Analysis does not include completed projects as existing projects are included in the
baseline (without project) assumptions and considered part of the environmental setting for issue
areas in Section 4 (Affected Environment).
5.9.2 Cumulative Effects
No impacts to the physical environment,terrestrial biological resources, cultural resources, nearshore
• of offshore marine sediment, or land use in the area are expected from the proposed action. The
proposed action, therefore, is not expected to have any cumulative effects with future or proposed
activities. Impacts to marine biological resources are expected to be beneficial and, therefore, no
negative cumulative effects are expected. Of the environmental resources considered in the
DEIS/DEIR(physical, biological, land use, aesthetics, offshore and nearshore marine sediment, and
cultural), only the impacts to air quality, land use/recreation, and aesthetic resources from the action
alternatives and planned/future projects are expected to experience cumulative effects.
Air Quality.
Construction emissions would occur over a large area from mostly mobile sources (i.e., tug boat
and/or hauling trucks) and only limited localized impacts are anticipated. (Note that as stated in
Section 5.2.3 emissions from the proposed action alternatives would not exceed SCAQMD
thresholds.) Since other projects proposed for the area are scheduled to be completed by the time
construction of the proposed dikes are initiated, construction related emissions from the various
projects are not expected to be cumulative.
5-21
Table 8. Cumulative Projects List
Projectt> Location Project 'T�pe Status/Estimated completion Date
Ocean Trails Golf Coastal bluffs just south of - 75 residential lots Construction underway for golf course and
Course' Bunker Point. - 4 affordable housing units approx. '/2 residential lots. Golf course tentatively
- 18-hole golf course w/clubhouse and scheduled to open by summer 1999. Site
261 acres maintenance facility improvements anticipated to be complete by
Public trails and open space 2002. Residential buildout based on market
conditions.
Altimira Canyon Storm Altimira Canyon north of P.V. Construct miscellaneous storm drainage In final design. Six-month construction estimated
Drain Improvements Drive So.,above Portuguese improvements. to commence in summer of 1999.
Point.
Long Point Specific P.V. Drive So.,between Long - Habitat Conservation/Enhancement Sept. 1999
Plan Point and Palos Verdes Point. - Public Parking,Trails and Paths,Beach Access
- 9-hole Golf Course
171.7 acres - Resort Hotel(400 rooms and 150 casitas)
- Resort Villas(32 Units)
- City Hall Facilities
Abalone Cove Sewer Abalone Cove residential Construction and operation of a sanitary sewer In planning stage. Six-month construction phase
System community north of P.V.Drive system anticipated to begin mid-1999.
So,overlooking Abalone Cove
and Portuguese Bend.
Abalone Cove Beach City Park site between P.V. Refurbish existing beach cabana and restrooms, In planning stage. Three-month construction
Park Improvements Drive So. and Abalone Cove build new shade structures,improve beach access phase may commence in late summer or fall of
shoreline road,construct new paved parking area near 1999.
beach.
Palos Verdes NCCP3 Coastal sage scrub in the study Habitat/natural resource conservation Currently under development
area
'Information provided by Otyof Rancho Palos Verdes Department of Planning;.Building and Code Enforcement
xlt;zs assumed that!:actions relative to stat alizing•the recent Ocean Trails Landslide will occur in a$ocattiot with this pio�ect
3See Section 4.4 for discussion of the Palos VetdesPeninsula NCCP
5-22
• • .
• Potential cumulative air quality impacts could occur from localized construction emissions, including
fugitive dust and emissions from trucks and other vehicles, along with exhaust from construction
equipment. Since the mainland quarry option could generate near-significant daily emissions of NOx
associated with truck traffic, and since fugitive dust emissions from dike construction could also
exceed daily particulate standards, there is a potential for significant cumulative construction
emissions (i.e., exceedance of SCAQMD daily emission standards) if multiple projects are under
construction at the same time. This impact would be temporary, perhaps for periods of minutes hours
during the work day and would not be concentrated in one area, due to the spatial distribution of the
projects listed in Table 8. Routine construction controls such as watering to control dust and proper
maintenance of equipment and vehicles to minimize exhaust emissions would also help reduce
cumulative impacts on air quality. Since a dike would not generate ongoing air emissions during its
operational life,it would not contribute to long-term, cumulative air quality impacts. Given the short-
term nature of potential construction effects, together with the absence of permanent air emissions
associated with a dike, no significant cumulative air quality impacts are anticipated.
Emissions from operation and maintenance would occur twice during the 50-year life of the project
under the nearshore dike alternative and once under the offshore dike alternative. No estimates exist
for projects 25 (or 50)years out, but they would probably be similar to projects presently proposed
(i.e., subdivisions). Emissions generated by future dike maintenance activities are not expected to
cause cumulative air quality impacts with the type of projects expected in the future life of the project.
• Land Use and Recreation. As stated in Section 4.4, the existing use in the area is primarily
residential and recreational. The proposed action is intended to restore high quality marine biological
habitat in Portuguese Bend and the downcoast areas. This may encourage snorkeling and scuba
diving of the area and possibly commercial fishing and commercial kelp harvesting of the area. This
increased usage, in combination with existing and future recreational use, is not expected to result
in significant adverse cumulative impacts to recreational or any other existing land usage(e.g., the
existing building moratorium, future commercial or residential development, potential NCCP preserve
areas, etc . . . ).
The proposed action would not contribute to any cumulative land use impacts, since it would have
no effects on the physical arrangement of any established land use and would not conflict with any
land use plans, policies or regulations. The proposed action would not generate any demand for or
have any direct effects upon land-based recreation sites or facilities and would not, therefore,
contribute to any cumulative impacts to existing or planned land-based recreation facilities.
Aesthetics. As discussed in Section 5.5, construction of a nearshore or an offshore dike would have
unavoidable, significant local impacts on the scenic ocean vista currently enjoyed by local residents
of the Portuguese Bend Area. None of the other projects listed in Table 8, however, would place any
structures within the marine environment and would not affect scenic views of the ocean water
surface beyond the limits of their specific sites. The proposed action, therefore, would not result in
significant cumulative aesthetic impacts at land-based viewing locations involving views of ocean-
•
5-23
jim
based structures. „
5.10 Relationship Between Short-Term Uses and Long-Term Productivity of the
Environment
The Council of Environmental Quality's (CEQ) regulations for implementing NEPA(40 CFR 1500)
require that the relationship between short-term uses of the environment and the maintenance and
enhancement of long-term productivity be discussed in Impact Statements. This includes effects
which narrow the range of beneficial uses of the environment or pose long-term health and safety
risks. In addition, the reasons why the proposed project is justified now, rather than reserving an
option for future alternatives, should be explained.
Implementation of the Action Alternatives would result in short-term adverse impacts associated with
construction of the dike as discussed in this Section(i.e., Section 5, Environmental Impacts). Over
the long-term, the effects of the action alternatives are beneficial, especially for marine biological
communities in Portuguese Bend and the nearshore areas immediately downcoast. The intent of the
action alternatives is to restore some of the habitat value historically associated with hard rock reef
habitat. As such, the proposed action should contribute to the long-term biological productivity in
the study area. The project is important at this time because of the scarcity of hard rock habitat in
Southern California. (Also see Section 2, Purpose and Need).
•
5.11 Irreversible and Irretrievable Commitment of Resources
Significant irreversible and irretrievable commitments of resources must be identified, as per CEQ
regulations for implementing NEPA. This includes non-renewable resources during the initial and
continued phases of the project which would be irreversible because a large commitment of such
resources makes removal or reuse unlikely.
During project construction, fossil fuels will be consumed by construction equipment and various
natural materials will be committed in the construction. For all practical purposes, the resources and
materials used in project construction are irretrievably committed to the project. Regular, routine
maintenance of the dike and dredging behind the dike (for the Proposed Action)will also require the
consumption of fuel by construction equipment and the commitment of construction materials. The
existing marine plants and animals that would be trapped behind the dike and subsequently buried by
eroded landslide material and/or buried underneath the dike will be irretrievably lost. (The habitat
area restored as a result of the action alternatives would,however, results in a substantial net increase
in the quality of marine plant and animal habitat in the study area.)
•
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• 5.12 Growth Inducing Impacts
As required by Section 15126(G) of the CEQA guidelines, an EIR must include a discussion of the
ways in which the proposed action could "foster economic or population growth, or the construction
of additional housing, either directly or indirectly." This discussion should also address characteristics
of the project which may encourage and/or facilitate other activities that, either individually or
cumulatively, could significantly affect the environment.
Currently,the unstable bluff and land above Portuguese Bend are under a building moratorium. As
the proposed dikes will not alter or stabilize the existing landslide whatsoever(in fact it is assumed
that the landslide will continue at, at least, its current rate throughout the life of the project), the
proposed dikes will not lead to a lifting of the building moratorium. No increased population growth
or residential/commercial development of the area will result from the construction of the proposed
dikes.
Restoration of high quality marine biological habitat may encourage snorkeling and scuba diving of
the area and possibly result in commercial fishing and commercial kelp harvesting of the area. These
uses are not, however, expected to significantly affect economic or population growth of the area.
•
•
5-25