Funding, Designing, and (eventually) Building Miles of Shoreline and Acres of Wetlands and Oyster Reefs on an Urbanized River!

Transcription

1 CW Gaskill City of Norfolk Funding, Designing, and (eventually) Building Miles of Shoreline and Acres of Wetlands and Oyster Reefs on an Urbanized River! Don Cole Brown and Caldwell C. W. Gaskill City of Norfolk

2 Outline Project background and history Objectives and grant metrics Challenges & solutions Lessons learned

3 Project Background and History Sandy Coastal Resiliency Grant for Lafayette River Awarded $4.6MM from NFWF Green Infrastructure Plan Public Education Shoreline Restoration

4 Project Location

5 Objectives and Grant Metrics Grant Metrics (Shoreline Restoration) 12,200/11,500 lf of shoreline restoration 3.34 acres of wetland creation 1.44 acres of oyster reef creation

6 Existing Conditions

7 Existing Conditions

8 Existing Conditions

9 Historic Conditions

10 Challenges Grant parameters Compressed schedule Restoration metrics Sea level rise Large storm events Biological integration Urban river Citizen concerns

11 Restoration Locations

12 Site Evaluation

13 Site Evaluation

14 Site Evaluation

15 Urbanized River

16 Selected Restoration Locations 7 projects identified to meet metrics 3 upper Lafayette River Required NW 27 coordination First phase design and construction 4 lower Lafayette River Require Section 408 and 106 coordination Second phase design and construction

17 Restoration Metrics Recommended Projects for Construction Project Shoreline Restoration Wetland Creation Oyster Reef Creation North Shore Road 804 lf 29,185 sf (0.67 ac) 15,246 sf (0.35 ac) Hermitage Museum 972 lf 107,593 sf (2.47 ac) 4,356 sf (0.10 ac) Hermitage East 872 lf 46,608 sf (1.07 ac) 18,731 sf (0.43 ac) Beach Avenue 896 lf 59,241 sf (1.36 ac) 24,394 sf (0.56 ac) Villa Circle 2,639 lf 104,979 sf (2.41 ac) -- Lindenwood/Barraud Park 2,458 lf 125,888 sf (2.89 ac) -- Norfolk International Terminal ~3,000 lf ~90,000 sf (2.06 ac) -- TOTAL ~11,641 lf ~563,494 sf (12.93 ac) 62,727 sf (1.44 ac) GRANT RESTORATION GOAL 11,500 lf 145,550 sf (3.34 ac) 62,597 sf (1.44 ac)

18 Compressed Schedule Analyzed and prioritized projects Quickly evaluated shorelines for suitability Concurrently gave NTP to surveyor on certain project sites 3 design teams to design sites simultaneously Projects prioritized based on proximity, length, ease of construction access, and ease of permitting Held early site meetings w/ USACE and VMRC to obtain early agreement on project feasibility

19 Schedule

20 Advancing the schedule Design Resources! Early and close coordination Design with construction in mind Construction City is looking to pre-qualify contactors Projects sized to attract large and small contractors Project sites logically clustered

21 Innovative Design Hybrid Sill Detail for Low and Medium Wave Energy Re-use Existing Concrete Debris and Rubble Oyster Bags on Top of Concrete (Counts toward oyster creation metric) 3:1 Seaward Slope (Typically 1.5:1 Slope) 16 Coir Log Landward of Sill Sill Height (Some Coordination with VIMS) Trip Waves Rather Than Block Consider 1.5 foot Sea-Level Rise in 50-years Set to Provide Natural Flushing of Created Wetlands Set to Improve Fisheries Connection Stormwater Outfall Treatment Estuary/Bay Type Design at Outfalls Below Sill Height

22 Innovative Design Wetland Micro-topography Provides Pockets of Habitat Engineering Principles as Foundation of Design Generate Wave Return Period Wave Generation Modeling (ACES) Geotech of River Bed Bottom Outreach to Lower Construction Costs Volunteers to Plant Tidal Wetlands (Spartina) Team with VIMS for Mussel/Clam Reuse and Conservation

23 Sea Level Rise Resiliency and designing for future conditions Sea Level Storm events Wave heights

24 Future Sea Level Estimate living shoreline lifecycle of 20 years 2013 VIMS Report: Recurrent Flooding Study for tidewater Virginia Sea level graphs utilized Low SLR scenario at 2036 is 1.5 High SLR scenario at 2036 is chosen as design goal Design sill crest 0.75 above current level Expect the Living Shoreline to adjust and to slowly rise in conjunction with SLR

25 Engineered approach Wave Prediction Utilized Wave Prediction Model Design aspects Determined top width of sill based on point where wave crash would occur Verified material size of sill Determined potential impact to proposed bank at shore

26 ACES Model Output

27 Permitting Held pre-app mtg w/ USACE to walk each site Addt l pre-app w/ VMRC and VIMS Helped determine up front all required permits: Section 408 Coord. Navigational Channels Section 106 Coord. Historic District Coord with VMRC for Public Oyster Ground and Private Lease areas Coord with USFWS under Migratory Bird Treaty Act

28 Lessons Learned

29 Lessons Learned Clock starts ticking with grant signing by grantor Understand locality processes with receiving these grants and including in timeline Account for learning curve by City staff on shoreline design Pre-evaluation of sites saves time and budget Engaging stakeholders truly saved time This was fun! Design is truly innovative

30 Thank you. Questions?