HomeMy WebLinkAbout3338; Agua Hedionda & Calavera Creek Dredging; Calavera Creek Rip Rap Replacements Project; 2005-09-21WETLAND DELINEATION STUDY FOR THE CALAVERACREEKRIPRAPREPLACEMENTPROJECT LAND USEJCOASTAL PLANNING LANDSCAPE ARCHITECTURE LA3900 POLICY AND PROCESSING ENVIRONMENTAL MITIGATION 1530 FARADAY AVENUE SUITE 100 CARLSBAD, CA 92008 (760) 931-0780 FAX (760) 931-5744 info@planningsystems.net * Prepared for: The City of Carlsbad Public Works Department 1635 Faraday Avenue Carlsbad, California 92008 21 September 2005
TABLE OF CONTENTS Summary of Findings 1.0 Project Description 2.0 Objective 3.0 Environmental Settings 4.0 Methods 5.0 Results 6.0 USACE Jurisdiction 7.0 Findings Appendix A
SUMMARY OF FINDINGS Implementation of the proposed Calavera Creek Rip Rap Replacement Project, in the city of Carlsbad, San Diego County, California will result in the permanent loss of approximately 0.13 8 acres of waters of the United States, a habitat under the jurisdiction of the U.S. Army Corps of Engineers (USACE). The habitat consists of 200 foot length of drainage channel, north of Don Lorenzo drive within the city of Carlsbad. Approximately 84 feet of the channel is earthen bottomed. The remaining 1 16 feet have been been previously coated in gunite concrete. The site is within an urban area of the city and is surrounded by ruderal, disturbed and developed lands. No species of plants or animals listed as rare, threatened, endangered or otherwise sensitive by the U.S. Fish and Wildlife Service (USFWS), California Department of Fish and Game (CDFG) or the California Native Plant Society (CNPS) are present on or adjacent to the site. The total area is 0.222 acres. The area within the project area that falls under the jurisdiction of the USACE and CDFG is approximately 0.138 acres. Implementation of the project will result in the permanent loss of 0.138 acres of jurisdictional habitat. The activity represents stabilization and reinforcement (maintenance) of an existing flood control improvement and thus under the conditions of USACE Nationwide Permit 3 does not require mitigation for the loss. The project will require a Streambed Authorization Pennit pursuant to Section 1603 of the California Fish and Game Code to cover the loss of 0.138 acres of streambed and bank that is under the jurisdiction of CDFG. A Section 401 water quality certificate (or waiver) will be-required from the California Regional Water Quality Control Board to permit the in channel placement of rip rap and the replacement of the gunite bank with Vmax P550 Turf Reinforcement Mat. Wetland Delineation for the Calavera Creek Rip Rap Replacement Project 1
1.0 Project Description The project involves replacement of 65 linear feet of erosion control rip rap rock that was placed on the south Bank of Calavera Creek, below Don Lorenzo Drive, in the Rancho Carlsbad development within the city of Carlsbad, California (Figure 1). The rip rap was emplaced under emergency conditions to reduce significant and rapid erosion that was occurring during flooding conditions of 10 January 2005. The project area has since been reviewed by a hydrologist to determine what permanent measures must be taken to stabilize the situation. The hydrologist recommends removal of the emergency laid rip rap and replacement with larger rock (1 ton) and replacement of existing gunite-covered banks with Vmax P550 Turf Reinforcement Mat. The proposed project area will impact approximately 200 linear feet of creek bank and bed comprised of 34 feet of vegetated creek bank, 50 feet of rip-rap and 1 16 feet of gunite-covered bank. There are four different surface types in the work area: vegetated creek banks, rip-rap covered creek banks, gunite-coated creek banks, and creek bottom (Figure 2). Surface Type 1 Total Project Area 1 3 Acres Vegetated Creek Banks Rip-rap Covered Creek Banks Gunite-Coated Creek Banks Creek Bottom 2.0 Objective - -- 0.106 0.026 0.044 0.046 The objective of this assessment is to determine the boundaries of USACE Section 404 jurisdictional wetlands and CDFG Section 1601-1603 jurisdictional wetlands within the proposed work area. This wetland delineation study will determine what percentage of the total 0.222 acre site must be classified as jurisdictional wetlands. 3.0 Environmental Setting Little Encinas Creek flows along the north edge of the Rancho Carlsbad mobile home park in a semi-natural dirt bottomed channel that has been straightened, stabilized and landscaped as part of the trailer park development process. The banks of the creek as it flows through the park have been heavily landscaped and in one section the side banks have been concreted to prevent erosion. The proposed rip rap project continues west from the edge of the concrete bank which is now being undercut by flow from Calavera Creek. Wetland Delineation for the Calavera Creek Rip Rap Replacement Project 2