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Ponds 6, 7 & 8. Napa Sonoma Marsh Restoration Group Meeting USGS San Pablo Field Station Office, Building 505, Mare Island September 26, 2006. Presentation. Project Overview Upper Ponds (8 & 7/7A) Goals and Solutions Ponds 6/6A Goals and Solutions Geotechnical Investigation and Survey
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Ponds 6, 7 & 8 Napa Sonoma Marsh Restoration Group Meeting USGS San Pablo Field Station Office, Building 505, Mare Island September 26, 2006
Presentation • Project Overview • Upper Ponds (8 & 7/7A) Goals and Solutions • Ponds 6/6A Goals and Solutions • Geotechnical Investigation and Survey • Schedule
Existing Conditions • Situated on former Napa River floodplain • Current Flow from Pond 8 to Ponds 7/7A to Ponds 6/6A • Pond 7 Bittern
Upper Ponds (8 & 7/7A) System Goals: • Perimeter Levee Improvement • Internal Levee Improvement (wave run-up) • Reduce Pond 7 Salinity to Acceptable Level • Mix Pond 7 Bittern with Tidal Flows in Mixing Chamber • Increase Tidal Flows to Mixing Chamber • New Outfall for Mixing Chamber Discharge into Napa Slough
Upper Ponds (8 & 7/7A) System Solution Options: Option 1: • Increase Flow to Pond 8 From Mud Slough • Improve System to Allow Increased Flows to Mixing Chamber Option 2: • Find Alternate Source for Mixing Chamber Source Water • Mud Slough Finger Into Pond 7A
Upper Ponds (8 & 7/7A) System Design Components: • Perimeter Levee Improvement • Internal Levee Improvement • Mixing Chamber Design • New Discharge Pipe/Control Structure at Napa Slough • New System to Increase Tidal Flows to Mixing Chamber
Ponds 6/6A Goals: • Perimeter Levee Improvement • Internal Levee Improvement • Demolish Siphon from Ponds 7/7A • Decrease Residence Time (one week)
Options: • New Intake from Napa Slough • New Intake/Outfall at China Slough (south side) • New Control Structure through Internal Levee • Outfall to Devil’s Slough • Outfall to Little Island Farms Ponds 6/6A
Design Components: • Perimeter Levee Improvement • Raise Internal Levee & Fix Breach • Demolish Siphon from Ponds 7/7A • New Systems to Improve Residence Time Ponds 6/6A
Geotechnical and Survey Scope Geotechnical: • Levee Walk to Assess Conditions • Geotechnical Scope for Upcoming Investigation Survey: • Field Survey to obtain Bathymetry and Topography for Design
Ongoing Tasks • Finalize Geotechnical and Survey Scope • Alternatives Analyses • Complete Geotechnical Investigation • Complete Survey • Plans to 50% - February 2007