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HomeMy WebLinkAboutCT 97-16A; Kelly Ranch; Tentative Map (CT) (3)1 1 1 1 1 1 1 1 Conceptual Wetland Mitigation Plan for the Kelly Ranch "Core Area" 1 • 1 1 1 1 1 1 1 • 1 1 Carlsbad, California May 14, 2001 Prepared by: Planning Systems 1530 Carlsbad, Faraday Avenue California 92008 I I I I I I I I I I I I I I I I I I I 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 eo S3_ n•ocoI w DC a.B. •o n O uc03 _>, "3 asbO• iHPH I I I I I I I I I I I I I I I I I 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 I I I I I I I I I I I I I I I I I I I 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. I I I I I I I I I I I I I I I I I I I 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 I I I I I I I I I I I I I I I I I I I 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. I I I I I I I I I A) 90 Day Performance Standards: I * Survival of 100% of the contractor installed container material. • Survival of 85% of the contractor installed cutting material. I I I I I I I I 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. I I I I I I I I I I I I I I I I I I I 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. I 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. I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I APPENDIX A PHOTOGRAPHS Site 1 - Showing Ruderal Vegetation and Eucalyptus Trees. Site 2 - Showing Ruderal Vegetation, Eucalyptus Trees and Proximity to Lagoon. I I I I I I I I I I I I I I I I I I I APPENDIX A PHOTOGRAPHS Site 3 - Showing Ruderal Vegetation, Transient Encampment and Proximity to Lagoon.