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Upper Petaluma River Watershed Flood Control Project Kent Gylfe Principal Engineer

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Presentation on theme: "Upper Petaluma River Watershed Flood Control Project Kent Gylfe Principal Engineer"— Presentation transcript:

1 Upper Petaluma River Watershed Flood Control Project Kent Gylfe Principal Engineer

2 Introduction

3 2005/06 New Years Day Flooding

4 Similar Studies in Three Watersheds Sonoma County Marin County Napa County Laguna Mark West Sonoma Valley Petaluma River Zone 2A

5 Planned Process – Phases of Work Feasibility Gaps Analysis Alternatives Analysis Design/ Construction Predesign/ Permitting Implementation Funding Visioning, Develop Objectives Concept Development Scoping Stakeholder Involvement FUTURE PHASES

6 Scoping Study Schedule Stakeholder input Stakeholder input May 2011 Sept 2011 Dec 2011 Oct 2011 Define project purpose and objectives Review data and consider problems being addressed, strategies, and issues Develop conceptual alternatives and screening criteria Identify priority concepts Review prioritization results Apr 2011 Dec 2011 Develop project implementation strategy

7 Project Participants SOLICITING INPUT FROM… Sonoma County Water Agency RMC Water and Environment Study Area Residents City of Petaluma Son. County Open Space & Ag Son. County Regional Parks Zone 2A Committee Friends of the Petaluma River Petaluma River Council North Bay Watershed Assoc. North Bay Agricultural Alliance United Anglers OWL Foundation Southern Sonoma County RCD The Bay Institute Petaluma Wetlands Alliance LandPaths Sonoma Land Trust Sonoma Mtn.Preservation Grp. Western United Dairymen River Clean-up Committee KOA Campground P.L.A.N. Regulatory Agencies

8 Project Basis Two core objectives – Provide flood hazard reduction – Increase groundwater recharge Seven supporting objectives – Water quality – Water supply – System Sustainability – Ecosystem – Agricultural land – Undeveloped land – Community benefits Projects are multi-benefit – Improve likelihood of outside funding – Provide additional implementation value – Broaden support by stakeholders and community Projects reflect input of partners, stakeholder groups, regulators and study area residents – Multiple workshops – Project tour Consistent with Water Agency mission and initiatives

9 Supporting Project Objectives

10 Project Concepts- Multi-Benefit Approach

11 Conceptual Locations General concept location criteria – Undeveloped land – Relatively flat – Relatively close to waterway or floodplain – Relative location to geologic formation Individual concepts have unique considerations Preferred project locations to be confirmed during Feasibility Phase based on additional criteria

12 Recharge Criteria Wilson Grove and Petaluma Formations are most effective for water supply recharge Alluvium above Wilson Grove and Petaluma also considered viable for water supply recharge Other alluvium could provide benefits other than water supply recharge

13 Concept 1: Managed Floodplain Goal: Maintain flood protection and recharge benefits provided by existing floodplain Continued effectiveness of downstream flood projects depends on avoiding upstream attenuation degradation

14 Concept 2: Off-stream Detention Goal: Divert high flows to temporary holding ponds for flood reduction and recharge Concept keeps low flows in the channel to maintain environmental conditions and sediment transport characteristics

15 Concept 3: In-stream Detention Goal: Detain high flows for flood reduction and recharge using the existing stream as a basis Possible to integrate multiple basin uses with waterway.

16 Concept 4: Floodplain Modification Goal: Create additional storage volume and potential recharge area using existing floodplains as a basis Same concept as Petaluma’s Denman Terracing Project Modified Floodplain Added Floodplain Storage

17 Concept 5: Levee/Floodwall Goal: Constrain flows to a narrower pathway than the existing floodplain Project impact area directly correlated with benefit area

18 Concept 6: Channel Modification Goal: Reshape channel section for increased capacity and recharge area Additional Hydraulic Capacity Minimal Impacts to Opposite Bank

19 Concept 7: Bypass Channel Goal: Divert high flows to parallel channel for flood reduction and potential recharge Concept keeps low flows in the channel to maintain environmental conditions and sediment transport characteristics Existing capacity leads to flooding At-grade bypass can reduce flooding Buried bypass can reduce flooding

20 Concept 8: Bridge Improvement and Debris Removal Goal: Improvement of bridge areas to reduce potential for flooding due to debris build-up Concept could lead to less emergency operations and maintenance

21 Concept 9: Low Impact Development Goal: Reduce development-related runoff and provide opportunity for recharge Many LID practices improve runoff water quality

22 Concept 10: Policy Review and Development Goal: Identify policies that impact flood hazards and groundwater recharge and update as necessary Collaborative concept could be applied at local or county-wide scales.

23 Concept 11: Direct Recharge Goal: Pump water directly into aquifers Better control of water quality entering aquifers than percolation methods

24 Concept Screening & Prioritization

25 Prioritization Process 2 Stages – Screening – Prioritization Is the concept suitable for this Project? Does the concept align well with the objectives (compared to the other concepts)? No Yes Concept Recommended for Feasibility Analysis Concept Pool

26 Screening Process Yes = Advanced to the prioritization process No = Not advanced to the prioritization process – Water Agency could consider participation through other venues Does the Concept Provide Flood Hazard Reduction and Groundwater Recharge (Key Project Purpose)? ConceptResponse 1. Managed FloodplainYes 2. Off-stream DetentionYes 3. In-stream DetentionYes 4. Floodplain ModificationYes 5. Levee/FloodwallNo 6. Channel ModificationYes 7. Bypass ChannelYes 8. Bridge Improvement & Debris Removal No 9. Low Impact DevelopmentYes 10. Policy Review and Development Yes 11. Direct InjectionNo

27 Objectives Support Concept Prioritization Core Objectives Screened Concepts Supporting Objectives Priority Concepts

28 Additional Project Types Low Impact Development (LID) Ecosystem enhancement Other smaller-scale projects Have the potential to: – Bring additional cost-share dollars to the table – Significantly increase the attractiveness of a proposed project to funding agencies – Generally broaden public support for a project among the community

29 Next Steps Dec 2011 Review prioritization results Dec 2011 Develop project implementation strategy Review worksheet input and comments Update concept descriptions and prioritization Identify focus locations for feasibility study Final public Scoping Study workshop Phase 2: Feasibility Study

30 Upper Petaluma River Watershed Flood Control Project Kent Gylfe Principal Engineer

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