Culvert Prioritization Model: Aiding Communities in the Selection of Priority Restoration Projects

Transcription

1 Culvert Prioritization Model: Aiding Communities in the Selection of Priority Restoration Projects Meeting #1 of the Technical Advisory Committee March 18,

2 Press 2 Prepared February 2016

3 Undersized Culverts! Culvert Sizes (~7,500 VT culverts) 6,000 5,000 69% Number of Culverts 4,000 3,000 2,000 21% 3 1, % 2% 3% < >125 Culvert Size (% of Bankfull Channel Width)

4 Project Goals 1. Create an easy to use Excel based tool for municipalities in prioritizing culvert replacements and stream crossing restorations. 2. The tool will be community driven with built in flexibility in weighing key environmental, engineering and road safety related factors in prioritizing road, stream crossing and culvert infrastructure upgrades prior to emergency repairs. 3. The aim is to get ahead of the storm and work with and train three municipalities in developing, field testing and implementing the tool The tool will be designed and available for all eleven municipalities located in the Piscataquog River Watershed.

5 Former culvert (MMI, 2015) New culvert 5

6 Scope of Work 1. Project Planning and Conceptual Design 2. Project Development Team and Outreach 3. Design Screening Tool 4. Run and Test Model 5. Create User Friendly Instructions 6. Project Team Review 7. Project Summary and Town Reports 8. Concept Designs and Community Outreach 6

7 Existing Information 7

8 Existing Information 8 (SNHPC, TU, DES, 2015)

9 Existing Information 9 (SNHPC, TU, DES, 2015)

10 Existing Information 10

11 Geomorphic Compatibility Screen 11 (Schiff et al., 2008)

12 Incorporating Culvert Restoration into Paving 12 (MMI, 2013)

13 Stream Power Total Stream Power (TSP) [W/m] = *Q*S Specific Stream Power (SSP) [W/m 2 ] = *Q*S / w Source: Bagnold, 1966 Source: Brierley and Fryirs, 2005 Source: Kleinhans and van den Berg, 2010

14 Flood Sensitivity Coarse Screen (Schiff et al., 2015)

15 River Sensitivity Coarse Screen 15 (MMI, 2015)

16 Culvert Vulnerability Screening Vulnerability Score < 0.4 >=0.4 to 0.6 >=0.6 to 1 High Medium Low Specific Stream Power versus Bed Resistance Specific Stream Power (W/m 2 ) Dominant Particle Size (Bed Resistance) Silt Sand Gravel Cobble Boulder Bedrock Structure Width Structure Width / Channel Bankfull Width (%) < 50% 50 75% >75 100% > % >125% Change in Slope Local Channel Slope Structure Slope (feet / feet) > 0.03 and <= 0.03 <= 0.02 > 0.02 and <=0 >0 and <=0.02 >0.02 and <=0.03 > Sediment Continuity Upstrea m Bed Downstream Bed Erosion None Aggradation Aggradation None Erosion Structure Alignment Skewed Aligned Legend Highest Vulnerability Lowest Vulnerability (MMI, 2016)

17 Culvert Vulnerability Screening 17 (MMI, 2016)

18 Culvert Vulnerability Screening 18 (MMI, 2016)

19 Draft Screening Draft Culvert Scoring System (V.2) GC = Geomorphic compatibility (NHGS) combined with a variable describing the predicted relationship between stream power and bed resistance (see below). Risk STR = An indicator of the structure condition from field observations combined with the approximate hydraulic capacity (TU/SNHPC) (see below). AOP = Aquatic organism passage (TU/SNHPC) plus fisheries prioritization data (NHFG). C = Criticality of the structure such as essential links, public safety routes, proximity to infrastructure, paving schedules, etc. (Town) R = Overall risk that is the intersection between vulnerability and criticality. Specific Stream Power & Bed Resistance Specific Stream Power (W/m 2 ) Dominant Particle Size (Bed Resistance) Silt Sand Gravel Cobble Boulder Bedrock GC Geomorphic Compatibility Aquatic Organism Passage AOP STR Structure Condition and Approximate Hydraulic Capacity Criticality C NEW CONDITION OTHER CONDITION (Potentially bad condition) Hydraulic Capacity Category Hydraulic Capacity Category Flood Pass Transition Fail Flood Pass Transition Fail (RI year) Hw/D< >1.15 (RI year) Hw/D< > L H H 2 L H H 10 L H H 10 L H H 25 L M H 25 L H H 50 L M M 50 L H H 100 L M M 100 L M H Risk Scoring Examples Risk Fisheries Prioritization Data (NHFG) AOP Category (TU) wild book trout sculpin / trout 0 0 dace only none Green Gray Orange Lowest Risk Low Risk Moderate Risk High Risk Highest Risk 19 Red Prepared February 2016

20 20 Anticipated Screening Results

21 Draft Screening Add power / resistance to NH GC screen Specific Stream Power & Bed Resistance Specific Stream Power (W/m 2 ) Dominant Particle Size (Bed Resistance) Silt Sand Gravel Cobble Boulder Bedrock Prepared February 2016

22 Draft Screening 22 Prepared February 2016

23 Draft Screening Fisheries Information (from NHFG) Fish Category Fisheries Prioritization Data (NHFG) wild book trout AOP Category (TU) wild book trout sculpin / trout?? dace only none sculpin / trout?? dace only none Green Gray Orange Red 23 Prepared February 2016

24 Draft Screening Criticality (Identified by Town) Critical link Near public safety Near infrastructure Replacement need aligns with paving cycle High traffic volume Near village center Risk AOP not in risk screen Vulnerability Criticality Risk GC STR C R 24 Prepared February 2016

25 Additional Slides 25

26 Recent Design Guidance 26 (Schiff et al., 2014)

27 Project Area 27

28 Funding Sources NH Department of Safety and Homeland Security FEMA NH Department of Environmental Services Aquatic Resource Mitigation (ARM) Funding Local Capital Improvement Programming Local Conservation Funding Local Bonding 28

29 Existing Hydraulic Capacity Information Hw/D> >Hw/D>0.85 Hw/D<0.85 (TU and SNHPC, 2014) 29

30 Screening Culverts for Risk Reduction and AOP (MMI, 2014) VT116 30

31 Geomorphic Compatibility Screen 31 (Schiff et al., 2008)

32 Retrofit Potential Screen 32 (MMI, 2008)