Watershed Nutrient Management: Stormwater BMP
- Effectively manage nutrients and sediment from urban and agricultural runoff
- Ideal for fluctuating water levels
- Easily retrofit into existing stormwater ponds
- Straightforward sizing protocol
- Quality-of-life restored to a functional waterbody
BioHaven floating islands efficiently treat runoff while delivering quality-of-life benefits. They act like a natural wetland, increasing the aesthetic value and wildlife abundance of any stormwater pond and farm pond. Easily installed, they protect the environment from harmful pollutants and sediments carried downstream by urban, industrial and agricultural runoff. In many US states, BioHaven floating islands have been approved as a BMP and can be used to gain nutrient credits.
- Capable of treating non-point source pollution throughout the watershed
- Deployed in retention ponds to trap scum and particulates, which are then mechanically and biologically sequestered
- No need to remove plants – in fact, to do so is counter-productive
- Installation is non-disruptive to the environment
- BioHavens have been proven by premier wetland scientists throughout the world. They can be trusted.
The BioHaven Solution
Description of Technology
The basis of the BioHaven solutions is the permeable, tiny fibers of the matrix, together with mature plants and extensive roots that grow through them. This makes up the massive surface area to support the growth of biofilm, a sticky substance that contains the microbes responsible for treating pollutants in stormwater. Through the processes of organic digestion, particle settlement, filtration, adsorption and direct uptake, BioHavens can treat oil and grease, excess nutrients and heavy metals. Put another way, pollutants are circulated through the islands and glom on to the sticky biofilm covering the root surfaces and island matrix. They either fall off into the sediments below when they get too heavy or are digested by the incredible food web inside the island and the plant-root mass.
BioHavens Floating Islands can be adapted to suit a wide range of situations with very little effort.
For example, they can be:
- Fit into any existing space or waterbody shape
- Operated in extreme climate or environmental conditions
- Designed to remove specific pollutants aerobically or anoxically
- Effective in fluctuating water levels, without drying out or being inundated
- Deployed to slow down flow and increase detention times
- Can be installed in stages to meet changing treatment requirements.
Design and Deployment Considerations
Sizing a BioHaven solution is based on a proprietary model based on historical data collected from a host of BioHaven-specific studies.
As far as possible, placement should take advantage of natural circulation to bring water into the treatment process. Aerators or circulators may be added to enhance circulation. Placement close to inflow and outflow is often most effective, though this may need to be balanced with aesthetic considerations.
Depending on customer preference, BioHavens can be anchored or tethered to shore.
Plants should be selected from a known range of species that thrive on BioHavens and produce a perennial, bushy root-mass. Hyper-accumulator plants can be recommended for specific parameters of concern (e.g. sulfates).
Waterfowl may need to be considered. They do not pose a threat to the islands, which are armored for protection, but may pluck out young plants. FII recommends using netting around the islands until the plants are well established.
BioHavens are very winter-hardy, withstanding cycles of freeze /thaw without impact. Perennial plants will revive along with their land-based counterparts. It may take up to 4 weeks after thaw for the islands to regain their normal buoyancy.
Maintenance involves periodically checking tethers, anchor chains and placement. Invasive plants and volunteers may need to be weeded out. Plants do not need to be harvested but may be trimmed periodically for neatness or to promote root growth.
Minimal Environmental Impact
BioHaven treatment approach requires zero land use, and has many other environmental benefits:
- Standard BioHavens require no power to operate
- Plants harmonize with the surrounding vegetation and create new habitat
- Reduces or eliminates the need for chemical dosing
- The manufacturing process is low-energy
BioHaven Floating Islands can effectively treat ponds, streams and ditches to restore a watershed to health:
- Effectively reduce algae blooms, cyanobacteria and Golden Algae
- Reduction in phosphorus and nitrogen halts widespread loss of aquatic life
- Reduction in fecal coliforms makes water healthier for humans and animals to drink
- Sediment trapping and removal prevents choking of pristine waters
- Prevention of erosion maintains stream and river bank integrity
Case Studies and Research
Successful treatment of industrial stormwater runoff using Floating Island Technology at a site in Billings, MT
Metra Park Industrial Area, Billings, MT, USA
This two-year study documents the success of an FTW installation in treating light industrial stormwater runoff.
Mermaid Pool: Passive Biohavens remove phosphorus in a New Jersey stormwater pond
Mermaid Pool, Somerset County, New Jersey
This study, undertaken by Princeton Hydro, demonstrates that even without added aeration, BioHaven floating islands qualify as a BMP for removal of phosphorus from stormwater ponds. They are effective even at low concentrations of 0.1 mg/L.
BioHavens north of Chicago win storm water BMP award for local conservation group
The Citizens for Conservation used BioHaven floating islands to augment a wetland for storm water treatment in a housing sub-division in Barrington, IL. Their algae problem disappeared and dissolved oxygen levels went up – and Sandhill cranes successfully reared chicks on the islands.