HomeMy WebLinkAbout3622; FARADAY ROAD EXTENSION; WETLAND MITIGATION PLAN; 2004-05-01INTRODUCTION................................................................................................................. ....................................... 1
LOCATION ....................................................................................................................................................................1
SITE CHARACTERISTICS..............................................................................................................................................1
RESTORATIONDESIGN ........................................................................................................................................4
GRADING .................................................................. ....................................................... ........................................ ....4.
IRRIGATION .................................................................................................................................................................6 PLANTING PROGRAM...................................................................................................................................................
MAINTENANCE.....................................................................................................................................................10
SELECTIVE WEED ABATEMENT ................. ............................ .................................................................................... 10
REPLACEMENT PLANTING ........................................................................................................................................10
CONTROL OF VANDALISM ........................................................................................................................................10
MONITORING AND SUCCESS ASSESSMENT ..................................... ................. ............................................. 11
REFERENCES..........................................................................................................................................................12
LIST OF TABLES
TABLE 1. IMPACT ACREAGE AND PROPOSED MITIGATION ............................. ........................................ .4
TABLE 2. RESTORATION PLANT MATERIALS ................ . ...................................................... .......................... 6
TABLE 3. RESTORATION SEED MIX FOR CISMONTANE ALKALI MARSH AREAS ............................ 9
TABLE 4. RESTORATION SEED MIX FOR DIEGAN COASTAL SAGE SCRUB AREAS...........................9
TABLE 5. HABITAT SUCCESS MILESTONES ................................................................................................... 11
LIST OF FIGURES
FIGURE 1. PROJECT VICINITY MAP ....... ........................................................................................................... 2
FIGURE 2. PROPOSED MITIGATION SITE ........................................................................................................3
FIGURE 3. PRELIMINARY GRADING PLAN FOR THE WETLAND MITIGATION SITE ........................ 5
FIGURE 4. HABITAT RESTORATION ZONES . ............................................................................ ..................... 7
FIGURE 5. TYPICAL PLANTING LAYOUT ............................................................................. ............................ 8
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Faraday Avenue - Conceptual Mitigation Plan •May 2004
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TABLE OF CONTENTS
Merkel & Associates, Inc. # 97-104-08 1
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Faraday Avenue - Conceptual Mitigation Plan May 2004
MILTIGATION PLAN
FARADAY AVENUE EXTENSION, -
SOUTH AGUA HEDiONDA SEWER INTERCEPTOR, AND
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. CARLSBAD OAKS NORTH BUSINESS PARK
Merkel & Associates, Inc.
May 2004
I INTRODUCTION
This mitigation plan addresses the wetland resources and waterways identified as being impacted by
I the proposed Faraday Avenue Extension, South Agua Hedionda Sewer Interceptor, and Carlsbad
Oaks North Business Park projects. Jurisdictional wetland delineation performed by Merkel &
Associates, Inc. (M&A) revealed that approximately 2.7 acres of wetlands and waterways would be
I impacted by these projects. These impacts consists of 1.4 acres of Southern Willow Scrub, 0.4 acre
of Freshwater Marsh, 0.4 acre of Cismontane Alkali Marsh, 0.1 acre of Disturbed Wetland, and 0.4
of Non-wetland Waters of the U.S.
This document provides revegetation plans to mitigate for wetland and non-wetland water resources
identified as being impacted by the proposed projects. Mitigation will be on-site, with 3.5, acres of
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creation and 12 acres as enhancement. Site preparation, consideration for hydrology and flood flows,
planting designs and materials, as well as maintenance and monitoring plans are included in this
conceptual mitigation plan.
I LOCATION
The proposed project site is located in the City of Carlsbad, to the northeast of the Palomar Airport
Road and El Camino Real crossing. The project site and proposed mitigation areas are located in
unsectioned lands of Township 11 South, Range 4 West of the San Bernardino Base and Meridian;
USGS
7.5' San Luis Rey, California Quadrangle (Figure 1).
SITE CHARACTERISTICS
The proposed mitigation site for wetland creation consists of a 3.5-acre area of Non-native Grassland
on the eastern side of the property near Melrose Drive (Figure 2). This area is adjacent to Southern
Willow Scrub and Southern Coast Live Oak Riparian Forest habitat. Impacts to the existing habitat
that are anticipated to occur as a result of the mitigation implementation have been considered under
the project environmental document and are incorporated into the environmental mitigation program.
I Mitigation will also consist of approximately 6 acres of wetlands enhancement and 6 acres of riparian
fringe enhancement. This enhancement will occur through the eradication of exotic Pampas Grass
and Tamarisk within on-site wetlands and surrounding riparian fringe areas that are not considered
I jurisdictional wetlands but which must be enhanced to prevent immediate reinfestation of the
wetlands by these species. The enhancement efforts are to be focused on the on-site removal of
exotics along the main La Mirada canyon fork of Agua Hedionda Creek and the two on-site
I .impacted tributary drainages including that paralleling the El Fuerte Road extension and the
freshwater seep drainage that lies within the open space north of the La Mirada fork of Agua
Hedionda Creek. While not a part of the proposed wetland mitigation, Oak Woodland mitigation
I under CEQA is also indicated on Figure 2 as it provides an integratiàn of restored habitats.
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Faraday Avenue - Cbnceptual Mitigation Plan May 2002
RESTORATION DESIGN
The mitigation plan has been designed to compensate for impacts by creating 3.5 acres of wetland
habitat from disturbed areas that are either dominated by non-native upland vegetation and which
also contains upland areas with little to no vegetation. The proposed mitigation will replace the
impacted wetlands and Non-wetland Waters as indicated below in Table 1. All the impacted wetland
habitats and Non-wetland Waters will be mitigated with an in-kind replacement except for disturbed
wetlands and non-wetland habitats that are to be mitigated by other represented wetland habitats.
In addition to the created mitigation habitat, enhancement is to be accomplished within 6 acres of
jurisdictional wetlands and 6 acres of wetland fringe habitats that are heavily infested by Pampas
Grass (Cortaderia sp.) and Tamarisk (Tamarix sp). Within this areas invasive exotics are to be
removed and the area is to be included within a perpetual managed conservation area under the
Carlsbad Habitat Management Plan.
The proximal placement of the restoration area to existing wetlands and Oak woodland habitat
restoration would enhance the quality of both the mitigation area and the existing wetlands by
combining the two to create a larger, diversified riparian habitat. Furthermore, since the surrounding
conditions of this area have supported the existing wetland, minimal preparation is needed to
establish the restoration area. The soils and hydrology are anticipated to be well suited to support the
additional riparian vegetation.
Table 1. Impact Acreage and Proposed Mitigation
Jurisdictional Type Impacted
Acreage.
Creation
. . . Mitigation
. Ratio
. Creation
Acreage
Enhancement
. . . Mitigation
Ratio
Enhancement
Mitigation
Acreage
Southern Willow Scrub 1.4 1:1 1.9 4:1 6
Freshwater Marsh 0.4 1:1 0.4
Cismontane Alkali Marsh 0.4 3:1 1.2
Disturbed Wetland 0.1 1:1 --
Non-wetland Waters of the U.S. 0.4 1:1 --
Total 2.7 . 3.5 6.0
GRADING
Minor grading is proposed for the mitigation area (Figure 3). Most of the mitigation site consists of
relatively flat terrain that is at a slightly higher elevation than the existing wetland habitat; therefore,
this area should require minor grading in order to create proper wetland conditions. The floor of the
mitigation area will slope towards the existing drainage at a 0.5% grade and will rise two feet above
the adjacent channel elevations. This elevation is well below the maximum elevations of adjacent
wetlands that are dominated by southern willow scrub habitats. Soil from the mitigation site grading
will be disposed of up-slope of the mitigation areas. and will be revegetated to a native sage scrub
habitat to create a buffer along the eastern edge of the mitigation site.
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Faraday Avenue - Conceptual Mitigation Plan May 2002
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IRRIGATION
I A temporary irrigation system will becorstrncted for the restoration site. This system will be
designed to provide water for the entire wetland mitigation. Operation of the system is to be under
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the control of the restoration specialist in order to avoid promoting excessive weed growth or
damaging target plant species. Toward the end of the monitoring period the system will be gradually
phased out to allow plantings to acclimate to the reduction in water availability. The irrigation
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system will be turned off a minimum of one year prior to the termination of the monitoring program.
The system will be abandoned with the removal of all above ground components (including risers
and sprinkler heads) subsequent to the end of the monitoring program.
I PLANTING PROGRAM
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Plant materials that would grow well within the proposed revegetation area were extrapolated from
adjacent wetland areas and are to be established in habitat restoration zones that take advantage of
the developed topography and hydrology of the site. Along the lowest elevations of the basin,
freshwater marsh habitat is proposed to be developed (Figure 4). Cismontane alkali marsh is
proposed on the poorly drained flats in the central portion of the mitigation site. Southern willow
scrub is proposed along the fringes of the mitigation site where greater soil drainage is expected to
foster growth of woody wetland vegetation. Container species to be utilized in the restoration work
are listed in Table 2 along with the unit sizes, approximate planting densities, and the total number of
units to be used. A typical section of the planting zones (Figure 4) is illustrated as a planting plan
within the restoration area (Figure 5). Seed mixes are to be used in areas to support cismontane
alkali marsh and Diegan coastal sage scrub upland buffer areas. Seed mixes are identified in Tables
3 and 4, respectively.
Table 2. Restoration Plant Materials
Species Unit Size Approximate Density Count (in clusters)
Artemisia douglasiana 1 gallon 5 foot centers on 782 Mugwort wetland fringe
Baccharis salicfolia 1 gallon 7 foot centers on 657 Mule Fat we wetland fringe.
Juncus acutus 1 gallon 5 foot centers on 306 Southwestern Spiny Rush wetland fringe
Populusfremontii 5 gallon 15 foot centers 180 Fremont Cottonwood
Rosa calfornica
1 gallon
5 foot centers on 490 California Rose wetland fringe
Rubus ursinus 1 gallon 5 foot centers on 524 California Blackberry wetland fringe
Salix exigua 1 gallon 7 foot centers on 269 Narrow-leaved Willow wetland fringe
Salixgooddingii
Gooddmg's Black Willow
1 gallon 15 foot centers 307
Salix lasiolepis
Arroyo Willow 1 gallon 10 foot centers 1430
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CALIFORNIA BLACKBERRY (RUBUS URSINUS)
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1" = 30' TYPICAL PLANTING LAYOUT 5
Merkel & Associates. Inc.
Faraday Avenue - Conceptual Mitigation Plan May 2002
Table 3. Restoration Seed Mix for Cismontane Alkali Marsh Areas
Species
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Lbs seed/per acre
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Suggested Purity/Germination
Artemisia douglasiana 0.5 15/50 Mugwort
Juncus acutus - - 2.0 90/60 Southwestern Spiny Rush
Iva hayesiana
San Diego Marsh Elder. 1.0 90/60
Distichlis spicata
Saltgrass : 0.25 20/40
Pluchea oderata
Marsh Fleabane .
0.25 40/20
Scirpus robustus
Prarie Bulrush .
1.0 90/60
Table 4. Restoration Seed Mix for Diean Coastal Sage Senib Aes
Species Lbs seed/per acre Suggested Purity/Germination
Artemisia calfornica
. 4.0 15/50 California Sagebrush
Salvia apiana
White Sage 4.0 70/50
Isomeris arborea 4.0 90/60 Bladderpod
Afriplex canescens 90/40 Four-winged Saltbush
Rhamnus crocea
Spiny Redberry 2.0 90/40
Baccharis sarothroides
Broom Bacchans -
2.0 05/40
Yucca shidigera 2.0 90/60 Spanish Bayonet Yucca,
Isocoma menziezii ssp. menziesii
Coast Goldenbush 2.0 20/40
Eriogonumfasciculatum
Flat-top Buckwheat 70 10/60
Lotus scoparius
Deerweed 6.0 9,0/60
Mimulus aurantiacus formapuniceus
San Diego Monkey-bush 2.0 5/50
Salvia mellfera 2.0 . 70/50 Black Sage %
Lupinus succulentus 3.0 90/80 Arroyo Lupine
Phacelia ramosissima
Caterpillar Phacelia 1.0 90/80
Salvia collumbariae
Chia 1.0 90/60
Eschscholtzia calfornica -
California Poppy 2.0 90/80
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Faraday Avenue -- Conceptual Mitigation Plan May 2002
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Any exotic, invasive plants cleared during the process of grading will need to be removed and
I disposed of properly. No soil amendments are proposed to be used. Planting will be in conformance
with the typical planting plan layout and will not use regular patterns, but more natual clustering and
distributions of plant materials.
I Container materials will be planted by excavating a hole with dimensions tha t are twice the diameter
and depth of the container. The sides of the holes will be irregular to allow for root petietration.
Each planting hole will be filled with water and allowed to drain prior to planting. Backfill will
I consist of site soils and all plants are to be thoroughly watered immediately following planting.
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MAINTENANCE
Maintenance of the restoration area will be .carried out over a 5-year period following the completion
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of all planting activities. Maintenance will consist of weed and exotic plant control, plant
replacement, control of vandalism, and incidental activities, as necessary, to ensure adequate
development of wetland vegetation. Early termination of the maintenance program would be
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. allowed if all fifth year success áriteria were met during any prior year.
SELECTIVE WEED ABATEMENT
I Weed abatementon-site will be performed to control particularly noxious or competitive species that
could inhibit the growth of desirable native vegetation. Hand weeding will be performed as needed
over the maintenance period. Exotic plants to be removed from the site will include, but not be S
I limited to, Pampas Grass, Tamarisk, Short-pod Mustard, Cocklebur, Castor-bean, Tree Tobacco,
Fennel (Foeniculum vulgare), and Russian Thistle (Salsola tragus). Other weedy plants that invade
the site in prohibitive numbers will be removed if they pose a significant threat to the growth or
I survival of the target vegetation
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REPLACEMENT PLANTING
Failed starts of tree and shrub materials will be replaced, as necessary, to achieve the restoration
goals or as prescribed in the monitoring program. As necessary, dead .plant materials will be
I .replaced by container-grown trees. Where micro-site conditions are more favorable for growth of a
different native riparian species of similar character (i.e., canopy tree, understory shrub), -plant
substitutions, as directed by the restoration specialist, may be made from the list of plants originally
I selected for planting at the site. This will allow reasonable assurance for the continued survival and
recruitment of plant materials. . ..
I CONTROL OF VANDALISM
The mitigation site will be posted as a habitat restoration area using all-weather, plastic-printed "No
I Trespassing" signs indicating who should be contacted with regard to any questions or concerns
about the site. Signs will be placed at site - access points. Temporary fencing or barriers will be
erected, if found to be necessary, along aôcess points to, discourage pedestrian trespassing and
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vandalism. Temporary fencing is not proposed unless access to the area is identified as a problem.
Trash removal will be performed, as necessary, to prevent damage to plantings. -
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Faraday Avenue - Conceptual Mitigation Plan May 2002
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MONITORING AND SUCCESS ASSESSMENT
I Monitoring of the site to assess the status of the revegetation effort will be initiated following the
completion of planting. Monitoring surveys will take place 0, 6, 12, 24, 36, 48, and 60 months after
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beginning the monitoring/maintenance period. This period will be shortened if final success
milestones are achieved early.
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The monitoring program will incorporate the use of fixed transects and photo plots to determine the
total plant cover within each planting zone, the percent cover of each species present, and the percent
survival of container revegetation materials utilized in the restoration program. In addition to
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transect monitoring, a general overview of the site will be made in order to assess overall compliance
with success criteria, species richness of the site, and areas requiring special modifications to the
maintenance program.
Progress milestones have been established in order to track project status and facilitate a successful
restoration project. Each milestone is accompanied by the maintenance required if the project fails to
reach the ultimate goals. Milestone requirements and corrective maintenance are outlined in Table 5.
Within one month following each monitoring period, a report detailing the results of the monitoring
and prescribed remedial maintenance to be performed will be completed. The results will be
provided to the California Department of Fish and Game, ACOE, RWQCB, and the City of Carlsbad
for review, comment, and general status information. Any comments on the monitoring program or
site conditions should be forwarded to the project-restoration specialist.
Table 5. Habitat Success Milestones
Milestone Assessment Criteria
- J Maintenance Action
0 Month Baseline information; no coverage criteria; all planting Plant densities brought up to meet requirements.
densities achieved.
100% survival of all container plants.
6 Months Target vegetation cover totals at least 10%. If cover or survival criteria fail to achieve minimum
standards, plant densities will be brought up to 100% of
80% overall survival of all container plants materials, the initial planting densities.
12 Months Target vegetation cover totals at least 40%. - If cover or survival criteria fail to achieve minimum
standards, plant densities will be brought up to 100% of
100% survival of all plants achieving 6 month milestone. the initial planting densities:
24 Months Target vegetation cover totals at least 60%. If cover criteria is not met, additional planting will be
performed to bring all areas up to initial planting
100% survival of all plants achieving 12 month milestone densities.
and/or 65% cover.
36 Months Target vegetation cover totals 75%. If cover criteria is not met, additional planting will be -
performed to bring all areas up to initial planting
Survival of individual units dropped as criteria. Natural densities.
recruitment of target vegetation exhibited along transects.
48 Months Target vegetation cover totals 80%. If cover criteria is not met, additional planting will be
performed to bring all areas up to initial planting
Natural recruitment of target species noted on transects. densities. Native riparian plant substitutions will be
made based on prevailing conditions and successful
Irrigation completely phased out. development of stock..
60 Months Target vegetation cover totals 90%. If parts of the revegetation failed to achieve the outlined
goals, an analysis will be made by the regulatory
Average canopy exceeds 6 feet and Arroyo Willows, agencies to determine reasonable alternatives which
Goodding's Black Willows, and Fremont Cottonwoods could be exercised to satisfy mitigation requirements.
exceed 9 feet.
Natural recruitment of target species noted on transects.
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Faraday Avenue - Conceptual Mitigation Plan May 2002
REFERENCES
Army Corps of Engineers. 1993. Habitat Mitigation and Monitoring Proposal Guidelines. June 1,,
1993
Bowman, R. H. 1973. Soil Survey, San Diego Area, California. U.S. Department Of Agriculture,
Soil Conservation Service And Forest Service, In Cooperation With The University Of California
Agricultural Experimental Station, The United States Department Of The Interior, Bureau Of
Indian Affairs, The Department Of The Navy, United States Marine Corps, The, Department Of
Housing And Urban Development, And The County Of San Diego Planning Department
December.
Hickman, James C., ed. 1993. The Jepson Manual, Higher Plants of California. University of
California Press, Berkeley. 1400pp
Holland, Robert F. 1986. Preliminary Descriptions of the Terrestrial Natural Communities of
California. California Department of Fish and Game. .
Munsell Color. 1974.. Munsell Soil Color Charts. Macbeth, a Division of Koilmorgeri Corporation,
Baltimore, Maryland. 0
Rogers, Thomas H. 1965. Geologic Map of California, Santa Ana Sheet (fifth printing 1985). State
of California, The Resources Agency Department of Conservation, Division of Mines and
Geology.
U.S. Army Corps of Engineers. 1987.. Corps of Engineers Wetlands Delineation Manual: Appendix
C, Section 1; Region 0 - California. Technical Report Y-87-1. U.S. Army Engineers Waterways
Experiment Station, Vicksburg, Mississippi
U.S. Department of Agriculture - Soil. Conservation Service. 1986. Hydric Soils of San Diego
County.
U.S. Fish and Wildlife Service.. 1988. National List of Plant Species that Occur in Wetlands:
California (Region 0). Biological Report 88. (26.10). May 1988 . . 0
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