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t Page 80 The reasons for'realigning the creek are as follows: • to eliminate floodplain areas from the horizontal landfill expansion areas; I F • to provide surface water run-on control for the horizontal expansion phases by eliminating the primary potential run-on source; F • to allow maximum capacity development of the site allowing refuse filling between the horizontal and vertical expansion phases;and • to eliminate the potential of subsurface wattr migration into the existing landfill waste by lining the creek channel. Additionally,the project proposes to create a landfill surface water detention to collect run-off(surface water)from the expanded landfill and to detain 100-year flood flows from the site. This feature,to be located in the southwest corner of the project site,would cover 4.3 acres, and would be fenced to restrict access. Collectively, 11.3 acres of surface water features(7.0 acres of realigned creek and 4.3 acres of detention basin)would be constructed as part of the proposed project. s The existing onsite portion of the North Branch of the South Fork of Little Johns Creek has been extensively modified and degraded by historic and ongoing site operations. As recently as two years,the channel was cleared of sediment and in-channel and bank vegetation for flood control purposes(Nisperos, E— Pers.comm.). Although several valley oaks grow along the banks(see discussion below),the creek does 1 not support any developed natural plant communities,and may have poor water quality. Nonetheless,it is likely an important local wildlife resource,and may support several special status aquatic species(see ' discussions below). i The Regional Water Quality Control Board also will need to issue water quality certification (or waiver) for the proposed project,according to Section 401 of the Clean Water Act. Section 401 water quality certification is necessary prior to final issuance of the Section 404 individual or nationwide permit,and also requires compliance with CEQA (i.e., a certified EIR). Execution of a Section 1603 Streambed Alteration Agreement with the CDFG may also be required for F relocation of this drainage prior to initiation of any on-site modification. The project proponent should' contact CDFG regarding the project's need for a Streambed Alteration Agreement at least 30 days prior to channel disturbance. Implementation of the measures presented below are intended to satisfy mitigation requirements/conditions attached to the CDFG Agreement,the Corps individual or nationwide permit, F and the RWQCB's Section 401 water quality certification. FiMitigation Measure F.1 Proposed as Part of the Project (a) The Wetland Mitigation and Monitoring Plan for the Austin Road Landfill Expansion(Jones and Stokes, 1996)will be implemented as part of the proposed project,consistent with the terms and conditions of the Section 404 Permit issued by the U.S. Army Corps of Engineers. The plan and permit post-date preparation of the 1994 EIR The plan provides for FI! FI' GRA&=I EMMONMENTAL CONSULTING