HomeMy WebLinkAbout3190; Rancho Santa Fe Rd Realignment & Bridge; Rancho Santa Fe Rd Realignment & Bridge; 2011-05-01o
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EXECUTIVE SUMMARY
This report reviews Year 3 of postinstallation maintenance and monitoring for the on-site
restoration (revegetation) of 0.54 acre of southern willow scrub along San Marcos Creek within
areas of temporary impact adjacent to Rancho Santa Fe Road Bridge. The construction project
widened and realigned Rancho Santa Fe Road from two lanes to a six-lane prime arterial
roadway. The project extends from approximately 100 feet south of the La Costa
AvenuelRancho Santa Fe Road intersection to approximately 100 feet north of the Melrose
Drive/Rancho Santa Fe Road intersection. The project also included the replacement of the
bridge crossing at San Marcos Creek.
Impacts to jurisdictional habitat (including state and federal wetlands/waters) included temporary
impacts to 0.97 acre and permanent impacts to 0.93 acre. Proposed mitigation was presented in
the Conceptual Wetland Mitigation and Monitoring Plan for the Rancho Santa Fe Road
Realignment and Bridge Replacement Project -City of Carlsbad, California (Dudek 2000).
Ba~ed on approval of the plan by the City of Carlsbad (City) and the resource agencies, permits
were issued in 2000 by the California Department ofFish and Game (SAA No. 5-142-00), U.S.
Army Corps of Engineers (404 Nationwide Permit No. 200001251), and Regional Water Quality
Control Board (401 Certification File No. 00C-045). In accordance with the mitigation plan, the
0.54-acre revegetation site is providing a portion of the mitigation for temporary construction
impacts. Because of bridge shading effects, the remainder of mitigation for temporary impacts
will occur at the project's off-site mitigation site within the University Commons property along
San Marcos Creek. Permanent impacts to jurisdictional habitat for the project will also be
mitigated at the 3.6-acre off-site mitigation area. Reporting on behalf of the City on the status of
the off-site mitigation area is provided within separate reporting.
After construction of the bridge was completed, implementation of the 0.54-acre on-site
mitigation, in the temporary impact areas, began in March 2007 and continued through August
2007. Implementation of this mitigation area included restoration of appropriate soil grades and
conditions, installation of a temporary overhead spray irrigation system, and install,ation of
specified native container plants and seed. Installation Was successfully completed in August
2007, which marked the beginning of the 120-day plant establishment period (PEP). The
120-day PEP was successfully completed on December 13,2007, which marked the beginning of
the 5-year maintenance and monitoring program for this site. Starting in 2008, Habitat West was
retained by the City to conduct site maintenance on behalf of the project. AECOM was retained
as a subcontractor to Habitat West and is conducting monitoring and reporting.
RSFR Realignment and Bridge Replacement Project
Wetland Mitigation On-Site Year Three Monitoring Report
OIlOROO 17 RSFR Hrulg. OI/-SlI, Yr 3 Momlorl/lll Rpl.doc 2 17 '2011
Page v
Overall, the project was successful during Year 3. Container plant survival of planted tree and
shrub species was more than 95 percent, and, based on visual assessment, native plant cover
averaged approximately 90-plus percent. In accordance with the mitigation plan (Dudek 2000),
botanical transect data were collected during Year 3 (July 2009). Based on the Year 3 botanical
transect data, native absolute cover was 101 percent. Total cover recorded along the transects
was more than 100 percent because of overlapping understory and overstory strata in portions of
the site. Native plant cover of 90-plus percent exceeded the Year 3 standard of 80 percent (60
percent from trees and shrubs, and 20 percent from understory species). As a positive indicator
of the site's suitability for southern willow scrub restoration, 20 wetland and riparian native plant
volunteer species were detected on-site during Year 3. In addition, weeds and exotic plant
species were effectively controlled and nonnative cover was maintained at less than 10 percent,
which met the standard of maintaining nonnative/exotic cover at less than 10 percent.
Container shrubs and trees are healthy and exhibited positive growth during Year 3. Arroyo, red,
and black willows range in height from 12 to 35 feet, with an approximate 22-foot average.
During Year 3, the mitigation habitat continued to develop understory, midstory, and early
successional overstory vegetation layers (strata). The mitigation area is also providing foraging
and cover habitat for wildlife. As the habitat continues to develop, it will become more
structurally diverse and suitable for a greater variety of wildlife species.
The temporary irrigation system was operated during a portion of Year 3 to help establish the
seeded and planted species. The irrigation system was permanently phased out on December 1,
2010 after Habitat West and AECOM determined that the mitigation plantings were established
and self-sustaining and no longer required supplemental irrigation. Discontinuation of the
irrigation system before the end of Year 3 is consistent with the project goal of the site being
without irrigation for at least 2 years (to demonstrate it is established and self-sustaining) before
the end of the 5-year maintenance and monitoring program.
Since the site met or exceeded its Year 3 success standards and no significant problems were
detected on-site, no remedial measures are recommended at this time. Specified maintenance and
monitoring will continue in Year 4 and through the remainder of the scheduled 5-year maintenance
and monitoring program. Maintenance will continue to focus on care of native seeded and planted
species, control of nonnative and exotic plant species, erosion control, and trash removal.
Horticultural monitoring during Year 4 will continue to focus on site conditions, presence of native
and nonnative species, and the overall health and development of the mitigation site. In addition,
quantitative transect monitoring will be conducted in Year 4 during the summer of20 11.
Page vi RSFR Realignment and Bridge Replacement Project
Wetland Mitigation On-Site Year Three Monitoring Report
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