Res07 14829 - Laserfiche WebLink

Browse Search

12/17/2007 marina bottom sediments and would create temporary water quality impacts, resulting in a potentially significant impact. Mitigation 9-3: Require the following mitigation measures to reduce water quality impacts associated with proposed project flushing channels dredging and marina filling operations: 1. As a condition of project approval, require the applicant to apply to the U.S. Corps of Engineers (Corps) for an Individual Department of Army Fill Permit, and abide by any conditions imposed by the Corps and its sister agencies of the Dredged Materials Management Office (DMMO) pertaining to the disposal of dredged sediments. 2. Contract with a water quality and sediment testing laboratory certified by the State of California to conduct an updated testing of marina and flushing channel sediments. Flushing channel sediments will have to be drawn as core logs during a pre-project, pre-excavation testing program. Results of the updated testing shall be submitted along with the Department of Army Permit application to the Corps, and the 401 Water Quality Certification request to the RWQCB. 3. Implement the dredging operations utilizing a suction dredge that minimally disturbs adjacent sediments (see Mitigation 8-1 herein). Confer with the Corps to determine the appropriate method for the site conditions (e.g., sediment characteristics) and the least environmentally damaging method for sheet pile/bulkhead installation and worksite segregation from Bay waters. Findings: Implementation of these measures would reduce the impacts of flushing channel dredging and marina filling operations to a less-than-significant level. D. Marina and Creek Sedimentation and Associated Creek/Bay Water Qualitv Impacts Potential Impact 9-4: Project implementation, including an approximately 9.50- acre reduction in marina open water area, would reduce the tidal prism (the water volume exchanged between higher high and lower low waters) which functions to scour tidal sediments from the marina entrances and from the lower reaches of Redwood Creek. Rates of siltation in these water bodies would increase. Future dredging and spoils disposal could be required at higher than existing frequencies, resulting in more frequent water quality disturbances and higher costs to the City. This constitutes a potentially significant impact. Mitigation 9-4: Require the following mitigation measures to reduce potential siltation impacts on the marina inlet channels and the project reach of Redwood Creek (extending to the Smith Slough confluence), corresponding dredging needs, and associated water quality impacts: 1. Require the applicant to conduct additional hydraulic analyses to verify to the satisfaction of the City Engineer that the marina inlets will operate at close to a self-scouring condition. If the analyses do not verify probable maintenance of such a condition, the project design shall be adjusted accordingly. Atty/Reso/Reso.1772 121707 26 14829 Muff# 613