HomeMy WebLinkAboutCT 97-16A; Kelly Ranch; Tentative Map (CT) (3)1
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Conceptual Wetland Mitigation Plan
for the
Kelly Ranch "Core Area"
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Carlsbad, California
May 14, 2001
Prepared by:
Planning Systems
1530
Carlsbad,
Faraday Avenue
California 92008
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Conceptual Wetland Mitigation Plan
for the
Kelly Ranch "Core Area"
Carlsbad, California
1. Proj ect Summary
Kelly Ranch is a largely undeveloped 432.4 acre property in the City of Carlsbad, San
Diego County, California. The "Core Area" of Kelly Ranch is 154.85 acres,
supporting the Kelly homestead, agricultural activity, and natural vegetation as
shown in Figure 1. A development project is proposed that involves the
subdivision and development of the Core Area for residential uses. The resulting
project will impact natural vegetation occurring on the site including wetland
vegetation and Waters of the U. S. This Conceptual Mitigation Plan is an
attachment to the "Biological Assessment and the "Natural Habitat Revegetation
Program", providing a conceptual framework for revegetation of wetland native
plant communities on-site.
A jurisdictional delineation of the waters of the United States was conducted for the
"Core Area" by Glenn Lukos Associates (GLA)(1). GLA has determined that without
the inclusion of a settling basin, created in 1986, the project will impact 0.06 acres of
jurisdictional waters. The impacts identified include two non-vegetated drainage
(0.02 acres each), and an isolated wetland (0.02 acre).
This Conceptual Mitigation Plan proposes that mitigation measures occur within
the 186 acre Upper Agua Hedionda Lagoon, presently offered for dedication to the
California Department of Fish and Game. Upland areas currently supporting
ruderal vegetation and Eucalyptus Woodland are identified as candidate locations
for non-tidal salt marsh. Small areas of southern willow scrub and/or freshwater
marsh may also be revegetated as site conditions indicate. The proposed
revegetation includes installation of container plants and hydroseeding, supported
by a fully automatic irrigation system. Plant installation will be followed by 5 years
of monitoring and maintenance for wetland plant communities.
2. Proposed Project Impacts
Three wetland areas totaling 0.06 acre, designated II, 12, and 13, as shown on the
"Wetland Impacts / Mitigation Map" (Figure 2), are impacted by the proposed
project. All wetland acreage and habitat descriptions are per the GLA report dated,
May 18,1999 (1).
Impact Area II and 12 - Two Non-Vegetated Drainage, (0.02 acre each)
1) Drainage A - is located in the mid-western portion of the site, is
approximately 720 feet in length, and comprises approximately 720 square feet
(0.02 acre) of Corps jurisdiction, none of which consists of jurisdictional
wetlands. The ordinary high water mark (OFIWM) is approximately one foot
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IMPACTS SUMMARY KNC I l_<"it'NI^' (III IVJ»"i I I
AREA NO.
II
12
13
DESCRIPTION
DRAINAGE A
DRAINAGE B
ISOLATED WETLAND
VEGETATION TYPE
NON-VEGETATED
NON-VEGETATED
RUDERAL WETLAND
TOTAL
ACRES
0.03
0.02
0.02
0.0fc
[ca^^^l PIEQAN COASTAL SAOE SCRUB
I TO&^^j REVEOETATED COASTAL SAGE SCRUB
WETLAND PLANT ASSOCIATIONS
SOUTHERN HILLOM SCRUB
MITIGATION SUMMARY
AREA NO.
Ml
M2
M3
EXISTING PLANT
COMMUNITY
EUCALYPTUS WOODLAND
RUDERAL
EUCALYPTUS WOODLAND
RUDERAL
DISTURBED MULEFAT SCRUB
EUCALYPTUS WOODLAND
PROPOSED REVEGETATION
/ RESTORATION
NON-TIDAL SALT MARSH
COASTAL SAGE SCRUB 'CUT SLOPE.)
NON-TIDAL SALT MARSH**
NON-TIDAL SALT MARSH**
TOTAL
WETLAND
ACRES
0.83
0.13
0.21
1.83
UPLAND
ACRES
0.01
0.01
TOTAL
ACRES
0.96
0.13
0.21
1.321
UPPER SALT MARSH
FREStWATER MARSH
OPEN WATER
SALT PANNE
TIDAL CHANNEL
** SCIAU. ASEXiS Of MULEFAT SCRUB, FRESHWATER MARSH, AND/OR SOUTHERN WILLOW SCRUB MAT ALSO BE
REVEQETATED IN AREAS M2 AND/OR M3 IF CULTURAL CONDITIONS FAVOR ESTABLISHMENT OF A FRESHWATER COMMUNITY.
LEGEND
DISTURBED DIEOAN COASTAL 8ASE SCRUB
BICALYP1US WOODLAND
RUDERAL
ORNAMELTAL / DEVELOPBD
DISTURBED
DISTURBED WETLAND PLANT ASSOCIATIONS
DISTURBED SOUTHERN WILLOW SCRUB
DISTURBED MULEPAT SCRUB
DISTURBED UPPER SALT MARSH
AREA C
NOT A PART
APPROXIMATE AOUA HEDICNDAOPEN SPACE DEDICATION AREA
' A i: _X
AREA A
NOT A PART DRAINAGE A
:DRAINAGE B
;<ELLT RANCH "CORE AREAAREA F / /— "
NOT A PART / /- - -
I3):JURISDICTIONAL WETLAND=
SOURCE NOTE:
PROPOSED WETLAND HPACT
PROPOSED DRAINAOE IMPACT
DISTURBED MULEFAT SCRUBPROPOSED AS A MITKkATION SITE
KELLY RANCH -CORE AREA'
NOTE:
MITIGATION AREAS Ml, M2, M3, ARE
AREAS NOT PREVIOUSLY IDENTIFIED
AS MITIGATION SITES.
FIGURE 2
WETLAND IMPACTS / MITIGATION MA
KELLY RANCH CORE AREA
VEGETATION IN THE UPPER AQUA HEDIONDA LA3OON WAS INVENTORIED
BY FRED T. SPROUU, BIOLOGIST, AND GRE<3 EVANS, LANDSCAPE ARCHITECT,
LA»S902>, IN THE SPRING OF 1991. A VEGETATION MAP WAS DRAWN IN THE
FIELD USING A 1ZXD SCALE AERIAL PHOTOGRAPH, AND A TOPOGRAPHIC
OVERLAY OF EXISTING SITE CONDITIONS.
IMPACTS ANALYSIS DERIVED FROM GLENN LUKO9 ASSOCIATES WETLANDS
ASSESSMENT LETTER REPORT, KELLY RANCH AT CARLSBAD, SAN DIEGO
0 250 500 PS #961238
REV. MAY
JULY
10, 2001
28, 1999
I FARADAY AVENU& SUITS 100. CARLSBAD. CA
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in width for the entire length of the drainage. No wetlands or riparian
vegetation are associated with Drainage A".
2) "Drainage B - is located in the mid-western portion of the site, is
approximately 525 feet in length, and comprises approximately 1,050 square
feet (0.02 acre) of Corps jurisdiction, none of which consist of jurisdictional
wetlands. No wetland or riparian vegetation is associated with Drainage B.
Impact Area 14 - Isolated Wetland, (0.02 acre)
An isolated wetland occurs along the mid-western boundary of the site. Vegetation
associated with this wetland area consists of ruderal wetland species including,
cocklebur (Xanthium strumarium) , curly dock (Rumex crispus), rabbitfoot grass
(Polypogon monspeliensis), common sow-thistle (Sonchus oleraceus), marsh-
fleabane (Pluchea odorata), arroyo willow (Salix lasiolepis), and Mexican tea
(Chenopodium ambrosioides), Approximately 1,071 square feet (0.02) acre of Corps
jurisdiction is associated with this wetland (1).
3. Proposed Mitigation Measures
Areas to be impacted by the proposed project are dominated by disturbed, non-
native vegetation, or support no vegetation at all. This mitigation plan proposes a
1:1 mitigation ratio for the wetland impacts identified. This ratio is proposed in
recognition of the poor habitat value of impacted areas, the manufactured nature of
the settling basin wetland, and the expected high value of the wetlands to be created.
Coastal sage scrub is proposed for revegetation on cut slopes created when
mitigation site elevations are lowered. Coastal sage scrub is proposed for restoration
in an area straddling two mitigation sites where disturbed coastal sage scrub
presently exists. Restoration of this upland habitat would create a contiguous area of
revitalized natural habitat, better capable of supporting indigenous faunal resources.
Mitigation Site Selection
Upper Agua Hedionda Lagoon is a 186-acre tidal-flushed basin supporting a
predominance of wetland vegetation, but also containing pockets of non-native
upland species that are candidates for restoration and revegetation. The dedication
area was surveyed in the summer of 1997 to identify plant communities in
preparation for offering to dedicate Upper Agua Hedionda Lagoon to the California
Department of Fish and Game (CDF&G). The survey was conducted by Fred T.
Sproul, Biologist, and Greg Evans, Landscape Architect, LA #3900.
The survey identified approximately 1.90 acres of eucalyptus woodland and ruderal
vegetation at three sites located in the extreme northeastern corner of the basin as
shown in Exhibit 2. Photographs of these sites are provided in Appendix A. The
Eucalyptus trees in the areas proposed as mitigation sites area gradually dying, likely
the result of increasing inundation or subsidence. Thus these sites make ideal
candidates for revegetation of wetland species.
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Eucalyptus trees do provide perching habitat for raptors. If resource agencies prefer
leaving dying and dead trees in place to allow for continued raptor use, the ground
level may still be lowered to allow for successful wetland vegetation establishment.
The lower ground level will eventually kill the eucalyptus trees, allowing wetland
vegetation establishment, while still providing raptor perches.
Proposed Revegetation
Three sites totaling 1.90 acres of non-native upland vegetation are proposed for
revegetation to 1.83 acres of wetland habitat and 0.07 acre upland habitat. In order to
make this upland habitat suitable for wetland vegetation it will be necessary to
lower the elevation of the site. Present elevations at the site range from 3 feet above
mean sea level (MSL) to approximately 0 feet MSL at the wetland boundary. It is
proposed that this area be lowered to the same elevation as the existing wetland
boundary. Best Management Practices (BMP) for control of sediment runoff will be
used during the grading required to lower these site. BMP practices include
delineation of the project site and installation of silt fences.
Wetland plant communities currently occur adjacent to the sites proposed for
revegetation. These wetland communities include: non-tidal salt marsh, mulefat
scrub, freshwater marsh, and southern willow scrub. The specific revegetation
pallet will attempt to match the plant mix on the habitat adjacent to each site. As
part of the restoration activity each site will be cleaned of trash, construction debris
and dead plant material prior to the placement of container plants and application
of the hydroseed mixture. The approximate revegetation acreage for each plant
community as shown below.
Table 1. Mitigation Summary
Area
Name
Existing Plant
Community
Proposed Revegetation /
Restoration
Wetlam
Acres
I Upland
Acres
Total
Acrei
Ml
M2
Eucalyptus Woodland/
Ruderal
Eucalyptus Woodland/
Ruderal
M3 Eucalyptus Woodland
Non-tidal Salt Marsh
Coastal Sage Scrub
(cut slope)
Non-tidal Salt Marsh**
Non-tidal Salt Marsh**
0.89
0.73
0.21
0.07
0.96
0.73
0.21
TOTAL 1.83 0.07 1.90
Small areas of freshwater marsh and southern willow scrub may be revegetated in these
locations where existing habitat indicates proper cultural conditions.
Lowering these sites to wetland levels will create small areas of slope between the
new wetland and the existing upland. These slopes will be revegetated with coastal
sage scrub habitat. It is estimated that these slopes will occupy approximately 0.05
acres. Additionally an area of disturbed coastal sage scrub occurring between
mitigation sites Ml and M4 will be restored to better quality coastal sage scrub
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habitat. Prior to the initiation of CSS restoration activities, a qualified restoration
specialist will determine if the upland restoration area should be raised to provide
greater probability for restoration success. Coastal Sage Scrub restoration will receive
supplemental irrigation, container plantings and seeding as determined by the
restoration specialist.
Prior to initiation of this project all easements and encumbrances will located on the
property and excluded from the revegetation activities.
Revegetation Program Objectives
To offset the loss of 0.02 acre of isolated ruderal wetland and 0.04 acres of non-
vegetated waters of the U. S. with:
• revegetation of 1.83 acres of non-tidal salt marsh,
• revegetation of 0.07 acres of coastal sage scrub,
To restore functioning salt marsh, and coastal sage scrub habitat that is self-
sustaining over time and capable of supporting native plant and animal species.
To insure to proper establishment of the habitat through the implementation of a
five year monitoring and maintenance program for wetland plant communities.
Coastal sage scrub revegetation will receive regular maintenance to assist in proper
establishment, but no monitoring is proposed.
4. Performance Standards and Mitigation Monitoring
Monitoring Methods
At the time that the initial planting effort has been fully installed, the non-tidal salt
marsh revegetation, (and southern willow scrub and freshwater marsh if installed)
will begin a five year monitoring period. Monitoring will occur quarterly during
the first year, and twice a year for the remainder of the monitoring period.
Quantitative data will be collected once a year using the "belt transect" or "point
intercept method" in order to evaluate survivorship, species coverage, and species
composition. Qualitative surveys, consisting of a general site walkover and habitat
characterization will be completed curing each monitoring visit. General
observations, such as fitness and health of the planted species, pest problems, weed
establishment, irrigation performance, mortality, and drought stress, will be noted
in each site walkover. The Revegetation Monitor will determine remedial
measures necessary to facilitate compliance with performance standards.
A map of transect monitoring locations shall be provided to the Corps for approval
prior to initiating long-term mitigation monitoring work. Transects must be located
to provide data for each plant community installed.
In the event that planting should fail to meet the specified requirements,
compliance will be ensured by the performance of either or both of the following
remedial procedures by the Landscape Contractor on an as-needed basis as directed
by the Revegetation Monitor: (1) replacing unsuccessful plantings with appropriate
sized stock or seed mixes to meet stated cover or survival requirements, and/or (2)
performing maintenance procedures to ensure the site conditions are appropriate
(e.g. non-native species removal).
Remedial actions in planting areas shall be based on detailed investigations (such as
soil test and excavation of failed plantings to examine root development) to
determine causes of failure.
Performance Standards
7.1 Performance Criteria
The revegetation plan proposes first to establish the same dominant plant species as
are found naturally in each plant community. In non-tidal salt marsh, low growing
ground cover are the key functional elements, those for which minimum cover
values are expected by the end of the monitoring phase. In small areas that may be
revegetated with freshwater marsh or southern willow scrub, larger trees, shrubs
and other plants will be installed to reflect the plant community character and
species diversity, such as arroyo willow, mugwort, tule, cattail, etc... The
composition and percentages of species installed will follow reference area transects
of existing habitats adjacent to each revegetation area.
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A) 90 Day Performance Standards:
I * Survival of 100% of the contractor installed container material.
• Survival of 85% of the contractor installed cutting material.
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B) First Year Performance Standards:
• Survival of 100% of the contractor installed container material, unless their
function and value has been replaced by natural recruitment.
• Achievement of 20% of ultimate vegetative cover of key vegetation, and 80%
survival of key species.
• Survival of 65% of containers planted.
C) Second Year Performance standards:
• Achievement of 40% of ultimate vegetative cover of key vegetation, and 80%
survival of key species.
• Survival of 65% of containers planted.
D) Third Year Performance Standards:
• Achievement of 60% of ultimate vegetative cover of key vegetation and 80%
survival of key species.
• Survival of 65% of containers planted.
• Supplemental irrigation must be shut off by year-end.
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E) Fourth Year Performance Standards:
• Achievement of 75% of ultimate vegetative cover of key vegetation and 80%
survival of key species.
• Survival of 65% of containers planted.
• No supplemental irrigation allowed.
F) Fifth Year Performance Standards:
• Achievement of 90% of ultimate vegetative cover of key vegetation and 80%
survival of key species.
• Survival of 65% of containers planted.
• No supplemental irrigation allowed.
Annual Reports
Annual mitigation maintenance and monitoring reports shall be submitted to the
Corps (cc: USFWS, and CDF&G). Vegetation will be analyzed to report on the cover
and relative dominance of all plant species. Height, spread, suckering and growth
measurements will also be recorded. Management recommendations should be
included that relate to the goals of the revegetation plan. Such recommendations
should include observations regarding: weed species and control, watering regimen,
replacement plantings, vandalism, encroachment problems or anything relevant to
the success of the project.
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I REFERENCES
• Glenn Lukos and Associates, Wetland Assessment for Kelly Ranch at
Carlsbad, California, Laguna Hills, California, May 1999.
' Planning Systems, Biotechnical Report for the Kelly Ranch Property, Carlsbad,
California, October 1997.
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APPENDIX A
PHOTOGRAPHS
Site 1 - Showing Ruderal Vegetation and Eucalyptus Trees.
Site 2 - Showing Ruderal Vegetation, Eucalyptus Trees and Proximity to Lagoon.
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APPENDIX A
PHOTOGRAPHS
Site 3 - Showing Ruderal Vegetation, Transient Encampment and Proximity to Lagoon.