Lower American River Bank Protection Workgroup 30Apr2024

00:09 Video start and introduction
08:20 30-Year History and Accomplishments of the LAR Task Force/BPWG, (Tim Washburn, SAFCA) 1986 Flood Response/Auburn Dam Proposal
09:37 Auburn Dam alternatives & formation of Lower American River Task Force
10:37 Erosion identified as long-term management issue
12:07 Erosion protection design development & formation of Bank Protection Working Group
15:27 1996 River Park levee repair & subsequent 1997 Flood
18:47 Additional erosion protection sites constructed using new design concepts & River Corridor Management Plan development
20:22 160,000 cfs flow conveyance benchmark
29:37 Hydrology of the American River Basin/Lower American River, (Ben Tustison, MBK) Overview of American River Watershed & mean precipitation
31:47 Types of flooding in watershed (snowmelt runoff & rain flood)
37:27 Where does precipitation and runoff go
39:57 Historical rain floods
41:57 Folsom Joint Federal Project & operation during flood events
49:42 Forecast Informed Reservoir Operation (FIRO)
54:32 Folsom Dam Raise and operational effects
1:07:47 Comprehensive Flood Risk Reduction Approach for the Sacramento Region, (Brian Wardman, NHC) Floodplain history
1:09:37 Folsom Dam construction and historical flood records
1:10:55 Flood management challenges and solutions (increase storage and controlled higher flows)
1:13:00 Conveyance infrastructure and levee failure methods
1:13:42 Flood risk and 1986 flood response: Folsom improvements and levee improvements, erosion protection remaining element
1:17:52 Status Updates on Contracts 1, 2 & 3A, (William Polk, USACE, Brian Wardman, NHC), Status of project designs (Contracts 1, 2, 3A, 3B, 4A)
1:19:22 Contract 1 (River Park), worst first - construction and revegetation update and effects of superficial erosion
1:25:28 Contract 2, Site 2-3 (Campus Commons) design considerations, including increasing flow capacity and creating gentler slope for river access
1:28:47 Contract 2, Site 2-3 revegetation progress- starts summer 2024
1:32:07 Contract 2, Site 2-3 pre-project conditions, project implementation including off-haul of 300,000 cy of material to reduce water surface, compaction remediation
1:34:07 Contract 2, Site 2-3 performance, recent lower bench inundation and fish habitat
1:36:33 Contract 2, Site 2-2 design and revegetation progress- starts summer 2024
1:39:50 Contract 2, Site 2-2 pre-project conditions, design and implementation
1:43:47 Contract 2, Site 2-2 winter flow condition, fish habitat
1:44:18 Contract 2, Site 2-2 Biotech alternative considerations & discussions
1:46:57 Contract 3A, Site 1-1 design and status overview, contract award 2024
02:01:37 Status Updates on LAR Bank Protection Contract 3B (Sites 3-1, 4-1, 4-2), (Brian Wardman, NHC and Dan Mielke, USACE)
02:01:37 Site selection process
02:02:07 2D Hydraulic model – developed post 2017, calibrated to 1997 event, includes effects of vegetation, Flora literature review
02:08:27 Trees on riverbanks provide limited erosion resistance
02:11:47 Levee failure processes: overtopping, erosion, under and through seepage
02:15:01 Site selection approach – river delineated into 81 individual segments
02:16:57 Expert Opinion Elicitation – local and national expert review of each segment and designate as Tier 1, Tier 2, Tier 3 coupled with Baseline Risk Assessment conducted by Risk Cadre (specialized multi-disciplinary risk group)
02:20:07 Existing Contract 3B site conditions: steep banks, undercut vegetation, past performance, weathered material
02:25:30 C3B overview/orientation: Sites 3-1, 4-2, 4-1 and typical cross section and project features – only high risk sections targeted
02:31:17 Design goals: collaboration, address lateral erosion and vertical scour potential, minimize habitat impacts, provide on-site mitigation
02:33:37 Design for different flow conditions – 160,000 CFS and also more seasonal flows that affect aquatic habitat800-2,600 CFS
02:34:29 Design process, including collaboration timeline, iterative phases 10%, 35%, 65%, 95%, 100%, addresses one of highest flood risk systems in USACE’s portfolio across the nation, over 100 individuals involved in design and review
02:37:31 10% design phase overview and concepts
02:39:40 35% design phase overview and concepts – determine that design had high habitat impacts and did not fully meet risk objectives and design needed significant alterations
02:43:37 65% design phase overview and concepts- started with a new Design Charette to evaluate alternatives and refinements, habitat impacts dramatically reduced
02:46:27 95% design phase overview and concepts- further data collection efforts, design refinements to meet flood risk objectives and minimize impacts
02:48:37 Cross section review of Sites 3-1, 4-1, 4-2