[Federal Register Volume 63, Number 29 (Thursday, February 12, 1998)]
[Notices]
[Pages 7131-7138]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-3614]
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DEPARTMENT OF DEFENSE
Department of the Navy
Record of Decision for the Santa Margarita River Flood Control
Project and Basilone Road Bridge Replacement Project at Marine Corps
Base Camp Pendleton, California
AGENCY: Department of the Navy, DOD.
ACTION: Notice of record of decision.
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SUMMARY: Pursuant to section 102(c) of the National Environmental
Policy Act (NEPA) of 1969, and the Council on Environmental Quality
Regulations (40 CFR parts 1500-1508), the Department of the Navy
announces its decision to construct a 14,500 foot-long levee and a
2,300 foot floodwall combination and associated stormwater management
system and a replacement Basilone Road Bridge at Marine Corps Base
(MCB) Camp Pendleton, California. The Environmental Impact Statement
(EIS) for these projects was prepared jointly by the Department of the
Navy and Army Corps of Engineers. In addition, the U.S. Fish and
Wildlife Service and the San Diego Regional Water Quality Control Board
served as cooperating agencies during the analysis of potential impacts
to the environment that may occur during construction, operation and
maintenance of these projects.
FOR FURTHER INFORMATION CONTACT: Mr. Lupe Armas, Assistant Chief of
Staff, Environmental Security, Marine Corps Base, Camp Pendleton,
California, 92055, telephone (760) 725-3561.
SUPPLEMENTARY INFORMATION: Pursuant to section 102(c) of the National
Environmental Policy Act (NEPA) of 1969, and the Council on
Environmental Quality Regulations (40 CFR parts 1500-1508), the
Department of the Navy announces its decision to construct a 14,500
foot-long levee and a 2,300 foot
[[Page 7132]]
floodwall combination and associated stormwater management system and a
replacement Basilone Road Bridge at Marine Corps Base (MCB) Camp
Pendleton, California. The Environmental Impact Statement (EIS) for
these projects was prepared jointly by the Department of the Navy and
Army Corps of Engineers. In addition, the U.S. Fish and Wildlife
Service and the San Diego Regional Water Quality Control Board served
as cooperating agencies during the analysis of potential impacts to the
environment that may occur during construction, operation and
maintenance of these projects.
Proposed Action
The Proposed Action consists of construction of a flood control
structure (a levee) at MCB Camp Pendleton to provide protection to
Marine Corps Air Station (MCAS) Camp Pendleton, the Chappo Area, Sewage
Treatment Plant (STP) 3, and the Santa Margarita Ranch House complex
from a flood event of up to 100 years in magnitude; a stormwater
management system to direct runoff from MCAS Camp Pendleton and the
Chappo Area into the Santa Margarita River without creating a flood
hazard; and replacement of a north-south circulation route across the
Santa Margarita River at or in the vicinity of Basilone Road and
Vandegrift Boulevard. The flood control structure would consist of a
14,500-foot-long levee and a 2,300-foot floodwall combination extending
from STP 3 to just upstream of the Santa Margarita Ranch House complex.
With this alignment, minimum airfield safety distances along the length
of MCAS Camp Pendleton would be maintained. The alignment would
transition sharply to run parallel to Vandegrift Boulevard downstream
of the airfield for approximately 2,300 feet, and finally would be
aligned to bulge out and around STP 3. The structure type would change
from earthen levee to a floodwall along the 2,300-foot run parallel to
Vandegrift Boulevard. This alignment would also include an upstream
guide vane to the main levee. This vane would improve the hydraulics of
the levee structure with respect to the impinging flow, and
significantly reduce scour depths at the upstream end of the levee and
the need for revetment protection.
The stormwater management system would drain surface runoff that
becomes trapped behind the flood control structure. The system would
have the capacity to manage runoff from approximately 2,100 acres,
including MCAS Camp Pendleton and the Chappo Area. The collected
stormwater would be pumped back into the river. The system would be
designed to manage a storm event with a duration of up to 24 hours and
a recurrence interval of up to 100 years.
The Basilone Road Bridge replacement project would involve
construction of a 1,155 foot long, two-lane bridge over the Santa
Margarita River. The bridge would be constructed to meet engineering
standards for transporting military loads, as well as providing surface
transportation for other users. The new bridge would allow water flow
to pass safely underneath the bridge during a 100-year flood event.
Rifle Range Road would be used for temporary access during project
construction. In preparation for this use, a ten foot corridor on
either side of the road would be maintained free of vegetation and the
road would be resurfaced. Upon completion of project construction,
Rifle Range Road would be removed and the area restored to the natural
river condition.
Purpose and Need
The basic project purposes for the proposed action are:
1. To provide protection for all U.S. Marine Corps assets within
the limit of the 100-year floodplain of the Santa Margarita River,
including the entire MCAS Camp Pendleton.
2. To provide a permanent, all-weather crossing over the Santa
Margarita River in the southeast portion of MCB Camp Pendleton.
MCB Camp Pendleton and MCAS Camp Pendleton maintain and operate
facilities and provide services to support operations of aviation
activities and units of operational forces of the Marine Corps. MCB
Camp Pendleton is the only west coast Marine Corps installation where a
comprehensive air, sea, and ground assault training scenario can be
executed; therefore, its ability to operate is considered to be of
paramount importance to national security. Facilities and operations in
the portion of MCB Camp Pendleton adjacent to the Santa Margarita River
are located in the 100-year floodplain for the river.
Heavy rainfall in 1993 resulted in the flooding of MCAS Camp
Pendleton, portions of MCB Camp Pendleton, and destruction of the
Basilone Road Bridge. The readiness and ability to support the missions
of MCB Camp Pendleton and MCAS Camp Pendleton were seriously
jeopardized because of the flooding and resulting damage. The flood
damage caused operations to cease in the flood damaged areas and
reduced the ability of the installation to perform the required
missions for a period of seven months. The flooding also damaged
structures and facilities, including buildings in the historic Santa
Margarita Ranch House complex, structures in the Chappo Area, and STP
3. A temporary bridge was erected on the site of the destroyed bridge
to reestablish the north-south road network.
To prevent future damage to property and the disruption of
essential operations, construction of flood control facilities is
required. These facilities would protect Marine Corps assets within the
100-year floodplain of the Santa Margarita River. In addition,
replacement of the temporary Basilone Road Bridge is required in order
to provide reliable north-south access across the Santa Margarita River
in the southeast portion of MCB Camp Pendleton. The bridge must
withstand a 100-year flood event.
Alternatives Considered
In preparing the EIS for the projects, an alternatives screening
analysis was performed. The selection criteria were based on the need
to optimize hydraulic control, sediment control, channel maintenance,
channel width, military mission, air station flight operations,
timeliness, project cost, water resources and biological resources.
These criteria are discussed in detail in Appendix C of the Final EIS.
A screening analysis of flood control options for the Santa
Margarita River evaluated an in-stream levee, an upland levee,
relocation of the air station, a concrete-lined channel, a soft bottom
channel, and an on-base detention dam. A previous evaluation of an off-
base dam/reservoir on De Luz Creek was also reconsidered. The concrete-
lined channel, soft-bottom channel, upland levee, on-base detention and
off-base detention alternatives, and the relocation of MCAS Camp
Pendleton were eliminated.
Camp Pendleton Alternatives Eliminated
1. Upland Levee
An upland levee would have to be adjacent to the runways at the air
station. This would violate air safety criteria and preclude routine
air station operations.
2. Concrete-Lined Channel
The height of levees on a concrete channel would intrude into the
flight path and violate airfield safety criteria and this alternative
would result in significant adverse environmental impacts.
3. Soft-Bottom Channel
The soft-bottom channel would not eliminate the need for routine
channel
[[Page 7133]]
maintenance and would result in significantly adverse environmental
impacts.
4. On-Base Detention Basins
Construction of on-Base basins would take an extensive amount of
time to design and permit, delaying flood protection for the air
station for an extended period of time. In addition, a basin would
reduce downstream groundwater recharge and would adversely affect
biological resources from both construction and inundation by water
held in the dam.
5. Relocation of MCAS
The possibility of off-site alternatives on MCB Camp Pendleton was
eliminated as infeasible based on the requirement that any relocation
of MCAS Camp Pendleton must successfully accommodate safe air
operations while minimizing impacts on the environment, local
communities, military operations, and military and civilian airspace.
The proposed flood control project would protect approximately 800
developed acres that include numerous buildings and facilities,
including MCAS Camp Pendleton. To relocate these facilities would
require the dedication of 800 acres of land either on or off base.
There would be potential significant impacts to listed species and
habitat in this 800 acres. In comparison, the proposed project would
permanently impact only 14.5 acres of habitat and 2.6 acres of
jurisdictional wetlands. The proposed project would have much less
impacts than relocating the facilities it would protect.
MCB Camp Pendleton operational siting constraints include potential
interference with ordnance impact areas, ranges and ground training,
amphibious, and aviation training activities. Important considerations
include the air safety restrictions associated with proximity to
training ranges. The locations of these ranges would cause approach,
departure, and pattern flight tracks to traverse restricted or
hazardous airspace.
There are 33 training areas at MCB Camp Pendleton that are used for
tactical exercise and field training, including cantonments, ordnance
impact areas (41,850 acres), and maneuver training areas. A deficiency
of live-fire ranges exists at MCB Camp Pendleton as addressed in the
Land and Training Area Requirements for MCB Camp Pendleton.
MCB Camp Pendleton is the only location on the west coast where
Marine Corps amphibious training operations can be combined with
elements of aviation activities to develop, evaluate, and exercise the
full range of combat techniques. Functions provided by the aviation
combat element include air reconnaissance, anti-air warfare, assault
support, offensive air support, electronic warfare, and control of
aircraft and missiles. Training for all of these functions is supported
by the restricted airspace and Military Operating Areas of MCB Camp
Pendleton.
Air Installation Compatible Use Zone requirements are another major
factor affecting the siting of MCAS Camp Pendleton. This program
includes analyses of Airfield Accident Potential Zones, Noise Zone
impacts, and Imaginary Surface obstructions. Underlying land uses must
be compatible with these restrictions and requirements.
Other geographic restriction criteria exclude relocation of these
facilities. There are limited areas of sufficient topography to
accommodate relocating this facility. Other constraints include
earthquake faults and steep topography. Direct seismic effects include
ground shaking and ground rupture, while indirect effects include
dynamic settlement, rock falls, and slope instability. Large areas in
excess of five-percent slope are also a constraint in locating an
alternative site for MCAS Camp Pendleton.
The Detailed Inventory of Naval Shore Facilities Report for MCAS
Camp Pendleton reflects the Current Plant Value (the return for selling
a particular building) as of September 30, 1995. The listed figure of
$235,213,000 was adjusted to $336,213,000 to include construction
between 1995 and 1999 which is underway. The costs to cover site
preparation, utility infrastructure to the site and environmental
mitigation was estimated at $64,000,000. This total estimate of
$400,000,000 covers only the 410 acres of the airfield area and does
not cover the almost 400 acres of billeting, personnel support,
maintenance, storage, office spaces and equipment parking located in
the surrounding areas of Camp Pendleton which support the 3d Marine
Aircraft Wing units that utilize the airfield. Current construction
costs at MCAS Camp Pendleton and MCAS Miramar for the same type
buildings shows that replacement costs would be significantly greater
then the Current Plant Value used to evaluate this alternative. In
comparison, the estimated cost of construction, mitigation, and
maintenance of the flood control project is $21.3 million. Permanent
all weather crossing of the Santa Margarita River would be required
regardless of the location of MCAS Camp Pendleton. The total cost of
relocating MCAS Camp Pendleton would be over 20 times the cost of the
proposed projects.
Off Camp Pendleton Alternatives Eliminated
1. Off-Base Dam/Detention Basin
An off-Base detention dam would lengthen the time required to
approve and construct flood protection, leaving MCB and MCAS Camp
Pendleton unprotected for a longer period of time. In addition, the
off-Base detention dam would reduce downstream groundwater recharge and
would adversely affect biological resources from both construction and
inundation by water held in the dam.
2. Relocation of MCAS
Off-Base relocation would include acquisition of property,
personnel requirements, infrastructure requirements, and base operating
costs. Relocating MCAS Camp Pendleton would include recreating the
facilities needed for the 3,100 personnel and 160 helicopters currently
assigned to MCAS Camp Pendleton. Additionally, as a result of the
implementation of decisions by the Base Realignment and Closure (BRAC)
Commission, two helicopter squadrons from MCAS Tustin and two
helicopter squadrons from MCAS El Toro will be relocated to MCAS/MCB
Camp Pendleton in 1999.
Marine Corps Bases/Air Stations are geographically positioned into
interdependent complexes of supporting installations on the East Coast,
West Coast, and in the Pacific. The major ground operational/tactical
base on the West Coast is MCB Camp Pendleton. MCAS Camp Pendleton lies
completely within the boundaries of MCB Camp Pendleton and allows for
intense helicopter operations without the requirement for excessive
transit time or flight within civil air space.
Other air stations within 200 air miles (near the upper-most range
limits for the CH-46 helicopters) of MCAS/MCB Camp Pendleton are MCAS
Miramar, Naval Air Facility (NAF) El Centro, Naval Air Station (NAS)
North Island, and March Air Force Base (AFB).
In accordance with the approved recommendations of the Base
Realignment and Closure Commission, MCAS Miramar will receive four
additional helicopter squadrons and associated support operations. MCAS
Miramar does not have the operational capacity or facilities to receive
MCAS Camp Pendleton's existing 3,100 personnel, 160 rotary-wing
aircraft with
[[Page 7134]]
associated maintenance and administration support resources in six
helicopter squadrons, and the four additional helicopter squadrons
mandated by BRAC.
The primary purpose of NAF El Centro is to support transient
aircraft using nearby ranges. However, the base was built in 1943 and
has severely deteriorated; the hangars are substandard, maintenance
facilities are insufficient, only one runway is operational, and the
remaining runways are closed due to their deteriorated condition.
Additionally, the distance, although less than 200 miles, is at the
upper limits for the range of CH-46 helicopters, thus requiring
refueling at Camp Pendleton to conduct operations and training in Camp
Pendleton airspace. Utilization of this facility would require huge
financial expenditures.
NAS North Island is located approximately one mile from Lindbergh
Field (the major commercial airport in San Diego, California) and is
adjacent to downtown San Diego. NAS North Island is considered fully
utilized at present with almost no expansion capability. Further,
training events such as helicopter touch and go and Ground Control
Approach (GCA) could not be efficiently conducted.
March AFB is in the process of being converted to an Air Force
Reserve Base and joint civilian use facility in accordance with the
1993 BRAC Commission's recommendations. The facilities are insufficient
and could not facilitate Marine Corps operational requirements.
Relocation to March AFB would require increased infrastructure, costs,
manpower needs, and delays in training.
Discussion of these other alternative air station facilities that
were considered but eliminated is contained in the Realignment to MCAS/
MCB Camp Pendleton EIS (BRAC EIS) which is referenced in the Final EIS
for the current flood control and bridge replacement projects.
In addition to the infrastructure costs associated with relocating
the MCAS on Camp Pendleton (if even possible), the relocation costs
off-Base would include land acquisition. This would include replacing
the approximately 800 acres, as well as other required replacements
such as additional family housing, recreational facilities,
commissaries and exchanges at the new location.
Proposed Levee Alternatives
The results of the screening analysis identified a levee and
associated stormwater management system as the most feasible and least
environmentally damaging flood control method. Three alternative levee
alignments were identified and analyzed in detail in the Final EIS.
Levee Alignment 3, the preferred alternative, is a 14,500 foot-long
levee and a 2,300 foot floodwall combination extending from STP 3 to
just upstream of the Santa Margarita Ranch House Complex. With this
alignment, minimum airfield safety distances along the length of MCAS
Camp Pendleton would be maintained. The alignment would transition
sharply toward and then run parallel to Vandegrift Boulevard downstream
of the airfield for approximately 2,300 feet, and finally would be
aligned to bulge out and around STP 3. The structure type would change
from earthen levee to a floodwall along the 2,300 foot run parallel to
Vandegrift Boulevard. This alignment would also include an upstream
guide vane to the main levee. This vane would improve the hydraulics of
the levee structure with respect to the impinging flow, and
significantly reduce scour depths at the upstream end of the levee and
the need for revetment protection. The guide vane would be constructed
in the same manner as the levee and would result in a significantly
smaller cumulative footprint and less potential impacts to riparian
habitat than the training structures proposed with levee alignments 1
and 2.
Levee Alignment 1 is a 16,585 foot-long levee extending from STP 3
north to approximately 1,000 feet upstream of the Santa Margarita Ranch
House Complex. This alternative would include three upstream flow
training structures and shaving of the hillside upstream of Basilone
Road Bridge. Minimum airfield safety distances along the length of the
MCAS Camp Pendleton airfield would be maintained. This levee alignment
would be a smooth line between the west end of the airfield and STP 3.
Levee Alignment 2 is a 15,200 foot-long levee extending from STP 3
to just upstream of the Santa Margarita Ranch House Complex. This
alternative would not include hillside shaving, but would incorporate
six river training structures upstream of Basilone Road Bridge and
several similar structures downstream of Basilone Road. This alignment
would be identical to Levee Alignment 1 from STP 3 to the downstream
side of Basilone Road. Minimum airfield safety distances along the
length of the MCAS Camp Pendleton airfield would be maintained.
Construction of a levee would require a stormwater management
system to drain surface runoff that becomes trapped behind the flood
control structure. The system would need the capacity to manage runoff
generated from approximately 2,100 acres during a 100-year storm event
with a 24 hour duration. The stormwater system would collect stormwater
and pump it back into the Santa Margarita River. Two alternative
stormwater management systems to accommodate surface runoff
requirements associated with each levee alignment were analyzed in the
Final EIS. For Levee Alignment 3, the preferred alternative, an
existing inundation area would be used for temporary management and
removal of stormwater through existing culverts under, and an earthen
ditch parallel to Vandegrift Boulevard, and then discharge into the
Santa Margarita River. The Stormwater Management System for levee
alignments 1 and 2 would use the same existing inundation area as Levee
Alignment 3, but an additional inundation area would be created behind
the levee and used to manage stormwater runoff. The inundation areas
used to manage stormwater for levee alignments 1 and 2 would
necessitate smaller emergency pumps than those required for Levee
Alignment 3.
Proposed Bridge Replacement Alternatives
A Camp Pendleton transportation planning analysis identified five
alternatives for the replacement of Basilone Road Bridge. Construction
of a suspension bridge was eliminated because it would violate airfield
safety criteria and compromise the operational readiness of the air
station. Construction of a new bridge at Hospital Road was eliminated
because it would bisect critical training areas and would not be
consistent with the operational requirements of the base. The remaining
three alternatives involve various alignments along Basilone Road. Each
of these three alternatives is summarized below as bridge alignments A,
B, and C.
Bridge Alignment A, the preferred alternative, will follow the
existing alignment. With this alternative, the temporary Basilone Road
Bridge will be replaced in its existing alignment providing a river
channel width of approximately 1,155 feet over the newly constructed
levee. The height of the new bridge will not cause an encroachment into
the runway approach-departure clearance zone of the MCAS Camp Pendleton
airfield; however, certain high profile vehicles (e.g., tractor-trailer
trucks), will intrude into the approach-departure clearance zone.
Traffic lights will be installed, which will be operated by the MCAS
control tower, to control the flow of traffic on the bridge to
[[Page 7135]]
prevent this encroachment during landings and take-offs of aircraft.
Bridge Alignment B is an east curve alignment. This alignment would
begin at the existing Basilone Road alignment on the north bank of the
river and curve to the east to avoid runway approach-departure
clearance zone encroachment from traffic on the bridge. Bridge
Alignment B would be slightly longer at 1,375 feet.
Bridge Alignment C, the Rattlesnake Canyon Road alignment, would
construct a new roadway and bridge alignment. The bridge would be
created about 1,200 feet northeast of the existing alignment and
southwest of the existing intersection of Rattlesnake Canyon Road and
Vandegrift Boulevard. With this alternative, a 2,000 foot-long bridge
would be constructed and 2,500 feet of new roadway would be required on
the north bank of the river.
A comparison of the three levee alternatives, three bridge
alternatives, and two stormwater management alternatives is provided in
Table 1.
Table 1.--Comparison of Alternatives
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Levee alignment 3 stormwater management:
pumphouse
-----------------------------------------
Influencing factor Bridge Bridge Bridge
alignment alignment alignment C--
A--existing B--east Rattlesnake
alignment curve Canyon
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Ground Disturbance--Permanent
(acres)...................... 25 25 27
Levee A................... 18 18 18
Spur Dikes/Silt Fences.... 0 0 0
Bridge Approaches (North &
South, feet)............. 3,150 3,150 8,650
Ground Disturbance--Temporary
(acres)...................... 66 66 85
Levee..................... 51 51 51
Spur Dikes/Silt Fences.... 0 0 0
Bridge and Roadway
Approaches............... 15 15 34
(2) Levee alignment 1
stormwater management:
pumphouse
Ground Disturbance--Permanent
(acres)...................... 67 67 69
Levee A................... 51 51 51
Spur Dikes/Silt Fences.... 9 9 9
Bridge Approaches (North &
South, feet)............. 3,150 3,150 8,650
Ground Disturbance--Temporary
(acres)...................... 76 76 95
Levee..................... 50 50 50
Spur Dikes/Silt Fences.... 11 11 11
Bridge and Roadway
Approaches............... 15 15 34
(2) Levee alignment 2
stormwater management:
pumphouse
Ground Disturbance--Permanent
(acres)...................... 41 41 43
Levee A................... 16 16 16
Spur Dikes/Silt Fences.... 18 18 18
Bridge Approaches (North &
South, ft.).............. 3,150 3,150 8,650
Ground Disturbance--
Temporary (acres)........ 75 75 94
Levee..................... 44 44 44
Spur Dikes/Silt Fences.... 16 16 16
Bridge and Roadway
Approaches............... 15 15 34
------------------------------------------------------------------------
AIncludes earthen levee, floodwall, guide vanes, roadway realignments,
and hillside grading as they apply to each conceptual project
alternative.
Rationale for the Preferred Alternative
The three alternative levee alignments and three alternative
Basilone Road Bridge Replacement alignments were combined to provide
nine project alternatives, which were evaluated in the Final EIS. The
no action alternative was also evaluated. The preferred alternative
(3A) combines Levee Alignment 3 and associated stormwater management
system, and Bridge Alignment A.
Hydraulic and Sediment Transport Analyses, conducted in February
1997, at the request of the Army Corps of Engineers, U.S. Environmental
Protection Agency, and U.S. Fish and Wildlife Service, concluded that
the proposed projects would not significantly alter the system-wide
geomorphology and river mechanics of the Santa Margarita River. Project
effects on flow depth, velocity, and sediment transport capacity would
be minimal and predominantly confined to three areas within the project
limits. Hydraulic and sediment transport effects upstream and
downstream of the project area would be negligible.
Although levee Alignments 1 and 2 would have more favorable cost
and engineering factors, Alignment 3 is the least damaging from an
environmental perspective. The design of alternative 3 avoids and
minimizes impacts to riverine habitats to the maximum extent practical.
Differences between Alignment 3 and the other levee alternatives
include elimination of proposed spur dikes and reconfiguration of the
downstream portion of the levee to a floodwall along Vandegrift
Boulevard. The preferred alternative represents a reduction of impacts
to riverine habitat when compared with the other levee alternative
alignments of 20 acres less direct permanent impact, 8.4 acres less
direct temporary impact, and 48 acres less indirect impacts due to
isolation of habitat. The preferred alternative has resulted in a
reduced impact to Corps jurisdictional waters of the U.S. and wetlands
by 7.8 acres less permanent impact, 4.2 acres less temporary impact,
and 30.9 acres less
[[Page 7136]]
impact associated with isolation of habitat.
Tables 2 and 3, respectively, show the permanent, temporary and
isolation impacts of the levee and bridge alternatives. In all cases,
levee Alignment 3 and Bridge Alternative A would result in lower
impacts to habitat and wetlands than the other alternatives considered.
The lower impacts to riparian habitat will translate to less impacts to
Federally-listed endangered species and other riparian dependent
species. Therefore, the preferred alternative would be consistent with
the requirements of NEPA and the Clean Water Act, is the least
environmentally damaging, and is determined to be the environmentally
preferred alternative.
Table 2.--Comparison of Habitat and Wetland Impacts Associated With Alternative Levee Alignments
----------------------------------------------------------------------------------------------------------------
Permanent impacts (acres) Temporary impacts Isolated acreage
--------------------------- (acres) --------------------------
Levee alternative --------------------------
Total Wetlands Total Total Wetlands
habitat habitat Wetlands habitat
----------------------------------------------------------------------------------------------------------------
1............................... 70.1 13.8 116.3 16.2 148 45.5
2............................... 29.6 10.1 37.5 14.9 129 42.3
3............................... 13 2.8 34.6 10.7 78.8 11.4
----------------------------------------------------------------------------------------------------------------
Acreage of wetland impacts is a subset of the acreage of total habitat impacts.
Table 3.--Comparison of Habitat and Wetland Impacts Associated With Alternative Bridge Alignments
----------------------------------------------------------------------------------------------------------------
Permanent impacts Temporary impacts (acres)
(acres) ---------------------------
Bridge alternative --------------------------
Total Total Wetlands
habitat Wetlands habitat
----------------------------------------------------------------------------------------------------------------
A......................................................... 1.5 0.3 2.1 0.6
B......................................................... 3.7 0.8 4 1.3
C......................................................... 5.8 1.2 7.5 3
----------------------------------------------------------------------------------------------------------------
Acreage of wetland impacts is a subset of the acreage of total habitat impacts.
Mitigation
The lower Santa Margarita River is an intact riparian corridor
ranging from 1,000 to 2,000 feet wide. The river corridor contains a
mosaic of riparian and freshwater marsh habitats, but suffers from
infestation by invasive, exotic weeds, primarily Arundo donax. The full
suite of hydrologic, biogeochemical, and biologic riverine functions
are performed at a level at or above most other rivers in southern
California. The Santa Margarita River supports some of the largest
known populations of the federally-listed endangered least Bell's
vireo, southwestern willow flycatcher, and southwestern arroyo toad.
Survey data from 1996 indicate the Santa Margarita River supports about
492 breeding pairs of vireo and 10 breeding pairs of flycatcher.
Because the proposed project will be built in the floodplain of the
Santa Margarita River, it will result in significant impacts to
wetlands, riparian habitat and endangered species. The following
provides a discussion of how these impacts will be mitigated.
Impacts to Corps jurisdictional waters of the United States and
wetlands (Table 4) would be mitigated by restoration of wetlands and
riparian habitat at Ysidora Flats. This 90 acre area is within the
floodplain of the Santa Margarita River, downstream of the proposed
project site. Ysidora Flats were historically separated from the river
by a series of berms and used for percolation and groundwater recharge.
The percolation ponds were damaged during the flooding of 1993 and
subsequently discontinued. The Marine Corps has removed the berms,
restoring the hydrologic connection between the area previously
encompassing the ponds and the river. The area has been recontoured,
and will be subject to ongoing invasive weed control and revegetation
with native riparian species. It is expected that most of Ysidora Flats
will become Corps jurisdictional wetlands and the remainder will become
non-jurisdictional floodplain riparian habitat. This area is being used
to mitigate the impacts of the previously authorized air station
expansion as well as the proposed project.
Table 4.--Mitigation for Impacts to Corps Jurisdictional Waters of the U.S. and Wetlands
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mitigation at Ysidora On-site revegetation Exotic weed control (per
Acreage of ------------------------------------------------------ BO)
Type of impact impact --------------------------
Ratio Acres Ratio Acres Ratio Acres
--------------------------------------------------------------------------------------------------------------------------------------------------------
All Permanent Impacts.................................... 2.6 3:1 7.8 0:1 0 10:1 26
Temporary Impacts to Freshwater Marsh.................... 5.2 1:1 5.2 a 1:1 5.2 1.13:1 5.9
Temporary Impacts to Riparian Woodland................... 5.1 1:1 5.1 b 1:1 5.1 2:1 10.2
Temporary Impacts to Unvegetated Waters of U.S........... 1 1:1 1 c 1:1 1 0:1 0
Full Isolation Behind Levee (all habitat types).......... 4.5 1.5:1 6.8 0:1 0 0:1 0
Partial Isolation Behind Guide Vane...................... 6.9
(5)Monitored until after the first 10-year event. If
impacts occur, mitigation would be 3:1 at Ysidora. If
impacts do not occur, no mitigation would be required.
[[Page 7137]]
Total................................................ 25.3 ........... 25.9 ........... 11.3 ........... 42.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
a Revegetation would occur via natural recruitment.
b Revegetation would occur via active planting.
c Area would be recontoured to pre-construction conditions.
All temporarily impacted areas, including wildlife habitat,
wetlands and waters of the U.S., will be kept free of invasive exotic
plant species for five years to allow natural revegetation. This
mitigation scheme is based on the Final Wetland Mitigation Plan for
BRAC Projects at the MCAS Camp Pendleton, which was published on
September 8, 1997. Monitoring concerning wetlands mitigation will be in
accordance with the provision of this Plan. Consultation shall take
place, prior to construction, with the Regional Water Quality Control
Board to determine any necessary changes in the National Pollution
Discharge Elimination System/Section 401 general permit.
Mitigation ratios for impacts to Army Corps of Engineers
jurisdictional areas are summarized in Table 4. The Marine Corps would
mitigate for indirect impacts to non-Clean Water Act jurisdictional
floodplain riparian habitat which would be isolated behind the levee by
either restoring jurisdictional wetlands at Ysidora Flats at a 0.33:1
ratio or by restoring non-wetland riparian habitat at Ysidora Flats at
a 0.5:1 ratio. This would translate, respectively, to 29 or 41 acres of
restoration at Ysidora Flats to compensate for loss of function
associated with floodplain isolation.
In addition to the mitigation required by the Army Corps of
Engineers, the U.S. Fish and Wildlife Service Biological Opinion (BO)
1-6-95-F-02 of October 30, 1995, requires that permanent impacts to all
habitat types (including Army Corps of Engineers jurisdictional areas)
be mitigated by removal of invasive weeds from the Santa Margarita
River at a 10:1 ratio. Temporary impacts must be mitigated by removal
of invasive weeds at ratios ranging from 0.5:1 to 2:1 depending on the
sensitivity of the habitat type being temporarily impacted. This BO
fulfills compliance requirements under Section 7 of the Endangered
Species Act. Monitoring for this mitigation will be accomplished as
provided for in the BO.
Sensitive habitats will be properly delineated to determine
construction zones and access roads. Lay-down areas will be located in
disturbed or developed areas, and shall be fenced when adjacent to
sensitive habitats. A qualified biologist shall monitor construction to
insure there are no inadvertent impacts to sensitive species. To
minimize impacts to arroyo southwestern toads during construction,
exclosure fencing will be constructed around the footprint to a height
minimum of 12 inches. In addition, surveys for this species and
monitoring will be conducted. No habitat will be cleared during the
breeding season of the least Bell's vireo and the southwestern willow
flycatcher (March 15-August 31).
The Santa Margarita River Estuary will be monitored for
sedimentation from construction activities. However, extensive
hydrogeomorphic modeling performed for this project indicates that
there should not be adverse downstream sedimentation effects. An
erosion and sedimentation control plan will be prepared prior to
construction.
Pre-construction surveys of biological resources and monitoring
plans will be provided to the U.S. Fish and Wildlife Service. Pre-
construction meetings with the U.S. Fish and Wildlife Service and the
Army Corps of Engineers will be conducted relating to biological
resources and to cultural resources. An upstream guide vane to mitigate
the potential for turbulent flow conditions and associated erosion
potential at the upstream end of the levee will be constructed as part
of the preferred alternative. Monitoring of the jurisdictional wetlands
and waters of the United States, partially isolated behind the guide
vane, will be conducted for a minimum of five years, which must include
a 10-year storm event.
Construction of the preferred alternative will require the
disturbance of an archeological site eligible for listing on the
National Register of Historic Places, and construction near the Santa
Margarita Ranch House Complex which is listed on the National Register.
Per 37 CFR 800.6(a), a Memorandum of Agreement, executed on February 5,
1998, among the U.S. Marine Corps, California State Historic
Preservation Office, Advisory Council on Historic Preservation, and the
Pechanga and Pauma bands of the Luiseno Mission Indian Tribe has been
implemented. This agreement provides for the preparation of an Historic
Properties Treatment Plan to specify the treatment for each historic
property, including archaeological sites and buildings, within the Area
of Potential Effect. This Agreement completes Section 106 requirements
of the National Historic Preservation Act.
Public Involvement
Preparation of the EIS began with a public scoping process to
identify issues that should be addressed in the document. Involvement
in scoping was offered through a combination of public announcements
and meetings with federal and state regulatory agencies. A Notice of
Intent (NOI) to prepare an EIS was published in the Federal Register on
January 9, 1996. In addition, copies of the NOI and Notice of the
Public Scoping Meeting were sent to federal, state, and local agencies,
as well as other interested parties; to radio, television, and print
media; and to libraries in the vicinity of MCB Camp Pendleton.
Advertisements announcing the scoping meeting were placed in several
local and regional newspapers and posted on the community calendars of
local cable television companies. The scoping period was from January 9
to March 10, 1996. A public scoping meeting was held on January 25,
1996 to solicit comments and concerns on the proposed action from the
general public. Comments received on the scoping process focused on
alternatives to the proposed action, alternative designs of the levee,
wetlands, water quality, biological resources, cultural resources, air
quality, and hazardous material handling during construction. The
Notice of Availability of the Draft EIS was published in the Federal
Register on July 18, 1997. The review and comment period for the Draft
EIS was from July 18, 1997, through September 5, 1997. A public hearing
regarding the Draft EIS was conducted on August 13, 1997. Comments were
received from 18 agencies and organizations that
[[Page 7138]]
identified the following major concerns; relocation of facilities out
of the floodplain, range and depth of alternatives, species and habitat
types impacted, potential effects to archaeological sites, river
hydrology and water quality, and wetlands. The Final EIS addressed
issues raised in comments to the Draft EIS. The Notice of Availability
of the Final EIS was published in the Federal Register on December 19,
1997. The Final EIS was distributed to federal, state, and local
agencies, interested parties, and public libraries on December 19,
1997, and the comment period closed on January 19, 1998.
Agency Decision
On behalf of the Department of the Navy and the U.S. Marine Corps,
I have decided to implement the proposed action through the preferred
alternative, Alternative 3A, (Levee Alignment 3--A 14,500 foot-long
levee and a 2,300 foot floodwall combination and Bridge Alignment A--
Existing Alignment). The requirements of applicable Executive Orders
have been considered. Specifically, the following determinations are
made with respect to these Executive Orders:
Executive Order 11988, ``Floodplain Management''. I have determined
that implementation of the Santa Margarita Flood Control Project is the
only practicable alternative, consistent with law and policy, to avoid
the potential severe consequences posed by potential significant flood
events to existing multi-million dollar facilities at MCB Camp
Pendleton and MCAS Camp Pendleton. All practicable means to avoid or
minimize harm to the floodplain are included within those mitigation
measures associated with the preferred alternative for this project.
Executive Order 11990, ``Protection of Wetlands''. I have
determined that the preferred alternative is the least environmental
damaging practicable alternative for the implementation of the Santa
Margarita Flood Control Project. I have further determined that the
preferred alternative incorporates all practicable measures to avoid or
minimize adverse impacts to wetlands which may result from this
project. In addition, all practicable mitigation measures to offset
wetland impacts will be implemented. This determination includes
consideration of, among other factors, the economic consequences and
the potential impact upon the national security missions of MCB Camp
Pendleton and MCAS Camp Pendleton posed by significant flood events
within the Santa Margarita River.
Executive Order 12898, ``Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations''. The
proposed action has been evaluated with respect to environmental and
social impacts, as well as access to public information and an
opportunity for public participation in the NEPA process as required by
this Executive Order. The project is consistent with the goals and
provisions of this Executive Order and no disproportionate impacts to
minority or low-income populations will occur.
I have determined that the preferred alternative is the least
environmentally damaging practical alternative for the implementation
of the Santa Margarita flood control and bridge replacement projects.
The Department of the Navy believes there are no remaining issues to be
resolved with respect to these projects. Questions regarding the Final
EIS prepared for this action may be directed to Mr. Lupe Armas,
Assistant Chief of Staff, Environmental Security, Marine Corps Base,
Camp Pendleton, California, 92055, telephone (760) 725-3561.
Dated: February 8, 1998.
Duncan Holaday,
Deputy Assistant Secretary of the Navy (Installations and Facilities).
[FR Doc. 98-3614 Filed 2-11-98; 8:45 am]
BILLING CODE 3810-FF-P