Floating Wetlands Pilot Project: Investigating the Potential for a New Stormwater BMP Karen Duhring Virginia Institute of Marine Science Center for Coastal Resources Management May 24, 2012
Floating Wetlands Pilot Project What are Floating Wetlands? VIMS Teaching Marsh Project Objectives Design Initial Monitoring Results Next Steps
WHAT ARE FLOATING WETLANDS? Manufactured floating platforms designed to grow plants in open water Used for water quality & habitat improvements
The islands are engineered to grow any type of plants. Nutrients for plant growth are obtained from the water. Microbial growth occurs in the matrix and among the plant roots. Both microbial and plant growth result in improved water quality. Islands function in any depth of water. At least 2.5 ft prevents rooting into benthic substrate during low water levels. Floating Island Southeast Hanging network of roots, rhizomes, and attached biofilms provides surface area for biochemical & physical processes
Potential Applications Urban stormwater ponds TMDL credits Wastewater lagoons Animal feedlots Fish farms Wetland replacement Fluctuating water levels Invasive species dominance Shoreline stabilization Aesthetic improvement Photos by Floating Island Southeast
FLOATING WETLAND PILOT PROJECT
William & Mary Sustainability Plan Carbon offset program Facilities management Energy & water use Transportation Student Green Fees $15 per student per semester $225K annually Project Awards granted by Committee on Sustainability April 2011 grant award for floating wetlands at 2 locations VIMS Teaching Marsh & Williamsburg campus
Floating Wetland Pilot Project Objectives Learn how to design & install Monitor plant survival & Phragmites invasion Monitor water quality before & after deployment (W&M campus only) Share experiences with other region projects Provide outreach education Involve students
VIMS Teaching Marsh Project Small shallow pond connected to Coleman Bridge stormwater detention pond Phragmites dominates pond edges Floating wetlands to increase plant diversity & treatment potential Freshwater Pond
VIMS Teaching Marsh Project Pond surface area approx. 576 sf 180 sf floating wetland (+ 30%) 3 12 x 5 ft sections Cable together or float separately $25/sf for basic design Cost range $25-30 per sq ft Cost depends on customization
Recycled PET plastic matrix 8 inches thick BioHaven Floating Island Injected marine foam for buoyancy Built-in anchor points PVC frame with cable to connect island sections together Design Specifications Planting holes on 8-inch centers through first 2 layers, 2.5 inch diameter circles Can be custom shaped
BioHaven Floating Island Design Specifications 4 layers in matrix PVC pipe for cable connection of separate modules Inert marine foam provides buoyancy
Plant Selection Popular, Versatile, and Available native plants for constructed wetlands as per DCR stormwater design specification No.13 Salt tolerance up to 5 ppt Occasional tidal flooding
Plant Selection Arrow Arum Soft Rush Pickerelweed Bulltongue Arrowhead Blueflag Iris Northern & Southern types Marsh Hibiscus Seashore Mallow Swamp Milkweed Joe Pye Weed New York Ironweed
Plant Purchase Edenton, North Carolina Genetically adapted to Carolinas & SE VA Container grown in large plugs $0.94 each
Large plugs, no soil used Approx. 2/3 of the holes planted for budget reasons
Tall flowering plants in center New York Ironweed, Swamp Milkweed, Joe Pye Weed Shorter plants around edges Pickerelweed, Peltandra, Bulltongue, Iris
Launch April 30, 2012 Cinder blocks & steel cable for anchors 2 anchor points per section
Launch April 30, 2012 Planted mat with anchors pulled into pond Anchors set based on proximity to Phragmites
Launch April 30, 2012 Only 2 of 3 sections installed at this time Look smaller in pond than on land
2 Weeks Later May 12 Noticeable loss of leaves weather & planting stress No evidence of muskrat grazing West section floating higher than east section Phragmites rhizomes reaching out but not touching
2 Weeks Later May 12 Northern blue flag Iris versicolor Healthy roots with new leaf growth
2 Weeks Later May 12 Removed dead leaves Pushed viable roots down into holes to make contact with water Recorded species survival
Initial Survival after 2 weeks Best Condition Hibiscus New York Ironweed Iris versicolor Switch grass Soft rush OK with wet roots Iris virginica Joe Pye Weed Pickerelweed Arrow Arum Bulltongue Not so good Seashore mallow
Lessons Learned So Far Purchasing process took longer than expected Delay planting until weather conditions are suitable, keep mats dry in the meantime Islands look bigger on land than in the water Push plugs all the way into holes Add soil if plant plugs are smaller than holes
Other Hampton Roads Projects VA Zoological Park, Norfolk VA Agriculture Experimental Research Facility, VA Beach Elizabeth River Project, Chesapeake Any others not mentioned here?
Next Steps Design, plant & launch 3 rd section Obtain water quality data from main campus project What is feasibility for TMDL credits? Facilitate network of Hampton Roads projects Share lessons learned & monitoring data Collaborate outreach efforts
Thanks for Your Interest Contact Information: Karen Duhring Virginia Institute of Marine Science College of William & Mary PO Box 1346 Gloucester Point, VA 23062 (804) 684-7159 karend@vims.edu
Open Discussion Any upcoming events of interest? Any final thoughts or questions? Please fill out Workshop Evaluation Workshop presentations will be posted to a web site Contact list of participants will be e-mailed Opt out of e-mail list with Dawn Fleming
Optional Field Trip Self-guided tour of VIMS Teaching Marsh & beach 3 stations with VIMS staff Floating Wetlands Salt Marsh Beach with Breakwaters and Planted Dune Limited facilities, use restrooms here Walk or drive to Boat Basin area
Boardwalk to Beach Parking Stations