Scope 9 (or 10) Shoreline Stabilization Approaches

Transcription

1 Sustainable Shorelines Comparative Cost Analysis Review Jon K. Miller, Ph.D. Andrew Rella Center for Maritime Systems Stevens Institute of Technology Scope 9 (or 10) Shoreline Stabilization es o Wood and Steel Bulkheads, Crib Walls, Live Crib Walls, Revetments, Rip-Rap, Joint Planting, Bio Wall, Sill, Vegetative Geogrid 3 sites o Poughkeepsie, Henry Hudson Park (Albany), Bowline Point Park (Haverstraw) 2 Sea Level Rise Scenarios o Current Rate (2.77mm/yr), Rapid Ice Melt (48 by 2080) 1

2 An engineering analysis for nine (10) shoreline approaches Traditional Bulkhead Timber Cribbing Revetment Rip-Rap Alternative Live Stakes/Joint Planting Live Crib Wall Green(Bio) Wall Sill Vegetated Geogrid Bulkhead Figure 4: Timber pile/wale bulkhead (NC DCM, 2008). Figure 5: Steel sheet pile bulkhead (photo credit: Emilie Hauser). 2

3 Revetment Figure 9: Rock revetment (NC DCM, 2008). Figure 8: Typical revetment cross-section (USACE, St. Paul District). Rip Rap Figure 15: Constructed rip-rap shore protection project (USDA, 1996). Figure 14: Typical rip-rap slope cross-section (NYS DEC, 2005). 3

4 Timber Cribbing Figure 20: Typical Timber Cribbing Cross-Section and Plan View National Engineering Handbook, August, 2007). Live Crib Wall Figure 22: Live crib wall installation (NYS SWCC, 2005). Figure 21: Typical live crib wall cross-section (NYS DEC, 2005). 4

5 Vegetated Geogrid Figure 27: Typical vegetated geogrid (Iowa DNR, 2006). Figure 25: Typical geotextile roll slope protection ( Live Stakes Figure 27: Figure 28: Typical joint planting (NYS DEC, 2005). 5

6 Sills Figure 49: Sill and marsh shore protection project. (Jefferson Paterson Park & Museum). Figure 48: Typical sill/perched beach cross-section (Jefferson Paterson Park & Museum). Green (Bio) Walls Figure 18: Laboratory study of wave run-up along a green wall (Herrington, et al., 2005). Figure 19: Laboratory study of circulation adjacent to a green wall (Herrington, et al., 2005). 6

7 For 3 different sites Bowline Point Henry Hudson Park Poughkeepsie Listed from lowest energy to highest energy Bowline Point Park, Upper Haverstraw Bay, Rockland County Site Characteristics Extremely Mild Slope (1:20) Shallow (~10 ft) Wide (15,000 ft) 7

8 Poughkeepsie, near Kaal Rock, Dutchess County Site Characteristics Extremely Steep Slope (1:1.5) Deep (~50 ft) Henry Hudson Park, Bethlehem, Albany County Site Characteristics Mild-Moderate Slope Shallow (~20 ft) Narrow (1,000 ft) 8

9 Cost analysis includes: Initial Costs (IC) o Material and labor costs to construct the stabilization measure Maintenance and Repair Costs (M&R) o Costs associated with routine maintenance and repairs (i.e. not associated with any given storm) Damage Costs (DC) o Costs associated with restoring a structure to its original function after a specific storm causes damage Replacement Costs (RC) o Costs of replacing a structure once it reaches the end of its serviceable life. (Typically associated with material decay/degredation) Designs based on: Data as originally presented in the Alden & ASA (2006) report. Additional information on wind wave climate. Main features considered so that reasonably accurate quantities could be developed. Wakes & Ice considered crudely through application of rules of thumb as detailed information for each site was not available. 9

10 Initial Costs Based on material & labor costs &/or bulk costs Every attempt was made to be consistent within and across methods Cost information was obtained from a combination of research studies and actual recent construction bids o Significant variability Consideration of Sea Level Rise: M&R costs increased for vegetated (+10%) and wood (+5%) structures Number of storms likely to be encountered and the damage costs resulting from them increase with SLR. Since the rate of SLR increases under the rapid sea level rise scenario, the 70-yr period is discretized into two 25-yr periods and a 20-yr period 10

11 s = n/t r 11

12 Present Day Dollars Inflated according to US Army Corps of Engineers, Civil Works Index System guide (1.7%). Discount rate 0f 4.0% (Federal guidance) Methodology follows US EPA s A Guide to Developing and Documenting Cost Estimates During the Feasibility Study 12

13 Conclusions Generally, a number of alternatives exist at each site for which the costs are relatively similar. Under the rapid ice melt scenario, all 3 sites will be underwater within 70 years Ecologically enhanced alternatives can be cost competitive with traditional approaches o Consistent with NOAA s Weighing Your Options report. Wake Analysis 13

14 Sites Out of 60 possible locations, nearly 40 acceptable locations were determined. Wakes were observed at a final number of 32 sites over the course of 4 days. Experimental Set-up 14

15 Sample Video 15