Cost / Benefit Analysis for the Restoration of Riverine Systems Impacted by Legacy Sediment Presented to2012 Choose Clean Water Conference Lancaster, PA By Conor Gillespie, CPESC, MBA Conor@landstudies.com May 2012
Existing Conditions Legacy Sediment Hydric Soils Basal Gravels Legacy Sediment is the impairment to the aquatic resource
Hard Armor Approach Cost $200 - $250 / lf Existing Grade Legacy Sediment Hydric Soils Basal Gravels Imbricated Wall Artificially Elevated Streambed Short Term Benefit Long Term Risk - Reduced erosion of impairment - Failure of armoring resulting in- Minimal improvement to aquatic resource renewed erosion of impairment
Soft Armor Approach Cost $100 - $150 / lf Existing Grade Legacy Sediment Hydric Soils Basal Gravels Bioengineering Short Term Benefit Long Term Risk - Reduced erosion of impairment - Failure of bioengineering resulting - Moderate improvement to aquatic in renewed erosion of impairment resource
Floodplain Restoration Cost $100 - $200 / lf Existing Grade Hydric Soils Basal Gravels Short & Long Term Benefit - Removal of impairment - Restored function of aquatic resource
Hydrologic Functions: Maximizing Sediment, Nutrient, and Carbon Retention in Natural SystemsBeaver Dam Controlled Stream Marshland
Potential Objectives of Riverine System Restoration Sediment and Nutrient Reduction Groundwater Recharge Stormwater Management Wetland Creation Regional Flood Reduction Carbon Retention Wildlife Habitat Improvement Invasive Species Removal Fisheries Improvements Thermal Improvements – Base Flow
Big Spring Run Restoration Restore the natural floodplain, stream and riparian wetland functions to its natural ecological potential. Maximize removal of nutrients and sedimentsSmall headwater stream/springs – characteristic of a sedge dominated wet meadow – Bog Turtle Habitat. Areas seasonally flooded and extremely wet. Frequent exchange and interaction between channels and floodplain.Over time, vegetation will encroach upon the channel increasing carbon, nutrient and sediment retention. The objectives willimprove over time and not be considered optimum immediately after restoration similar to the previous projects discussed.
Full-Depth Floodplain Restoration Design Features Channel directly linked to groundwater/bedrock. Floodplain Elevation – Preferably 6 to 12 inches withvernal pools to maximize – retention areas. This allowsthe root zone to quickly access and stabilize thefloodplain. Planform is sinuous, single, multi-thread channel or nodefined channel; similar to headwater marshes or wetmeadows. Maximize width of floodplain and condition soils forvegetation/root penetration. Woody debris throughout channel(s) & floodplain.
Cost Benefit Analysis Big Spring Run Case Study 3,060 lf of RestorationBenefit Value Hard Armor Soft Armor Floodplain $225 $125 Restoration $170Total Cost $688,500 $382,500 $522,500Stream Mitigation Dollar Values Vary Mitigation Possibly Mitigation Mitigation Achieved by State Achieved AchievedWetland Mitigation $77,500 / ac $0 $0 $310,000$ / ac* ($60,000 - $85,000) (4 ac)Wildlife Habitat Conservation Minimal Medium Maximum Banking CreditsSediment / Nutrient N – $3.37 ??? / yr ??? / yr ??? / yrReduction (On-site)** P – $4.73 Short term Short term Long TermSediment / Nutrient N – $3.37 $0 / yr $0 / yr ??? / yrfrom upstream sources P – $4.73 Transport Transport RetentionLegacy Sediment Re- $14 $2,380 $4,760 $280,000use*** $3 - $25 / cy (170 cy) (340 cy) (20,000 cy)Floodwater Storage None Minimal 12 ac/ftInfrastructure Maint. Likely Likely MinimalRequirements*Courtesy of Resource Environmental Solutions, LLC; Estimated Wetland Mitigation Credit Prices for the State of PA based offcurrent market conditions** Prices based of results of PennVEST Spot and Forward Nutrient Auctions; October 28, 2010 - March 21, 2012*** Courtesy of Joe Sweeney, based on estimated re-sale value of Legacy Sediment from Big Spring Run project
Cost Benefit Analysis Big Spring Run Case Study 3,060 lf of RestorationBenefit Value Hard Armor Soft Armor Floodplain $225 $125 Restoration $170Total Cost $688,500 $382,500 $522,500Total Monetary Benefit $2,380 $4,760 $590,000Simple Return on - 99.65% - 98.75% 12.9%Investment Additional Site Specific Benefits with Monetary Value - Sustainable, Low Impact Site Development - On-site water retention and usage - Reduction in stormwater fee’s due to increased infiltration Future Market Drivers - MS4 Permit Requirements - Chesapeake Bay TMDL’s - Wetland Creation & Mitigation