EWRI - Kansas City Construction and Performance of Bioretention Cells G.O. Brown, R.A. Chavez, D.E. Storm, and M.D. Smolen

EWRI – Kansas City Objectives  Demonstrate use of bioretention cells to improve water quality; primarily P reduction.  Develop simple to follow design procedures.  Quantify cell hydrology.  Long-term test of fly ash in filter media. 8: at Grove on Grand Lake 2: at Stillwater, including a control pair

EWRI – Kansas City General Design  3% to 5% of area.  Sized for runoff:  ½” in pool  ½” in filter  1’ topsoil.  Sand plug on 25% of surface for infiltration.  Filter media a blend of sand and 5% fly ash.  Overflow designed for 50 year, 1 hour storm.

EWRI – Kansas City A high-tech hole in the ground

EWRI – Kansas City Infiltration plugs minimize standing water  Designed to only pond water for 24 hr.  Addition of sand “plugs” on surface compensate for lower conductivity of top soil.  25% of surface layer are sand plugs with a specification that none touch.  Proved to be easy to construct and effective. plug

EWRI – Kansas City Class C fly ash significantly reduces P and metals in effluent  Batch sorption for Kd  Column experiments simulated leaching within the cell.  BCTs were fitted to find transport parameters.  Long-term effluent modeled with fitted parameters.

EWRI – Kansas City Phosphorous adsorption K d, mL/gRetardation Peat moss-5.81 Teller loam0.413 Dougherty sand2.111 Expanded shale (MO)1.27 Limestone1260 Expanded shale (KS)2801,400 Class C Fly ash218011,000

EWRI – Kansas City Fly ash will provide long-term P reductions Effluent P Concentration Exceeds Lifetime, yr PavementLawn mg/L mg/L mg/L3699 Lifetime of filter calculated assuming 1 ppm P inflow Runoff volume from pavement will be higher than lawns. Assumes reversible adsorption.

EWRI – Kansas City Fly ash significantly reduces K  Adding fly ash decreased the hydraulic conductivity of the sand exponentially  Maximum 5% fly ash in Dougherty K s =3.6 cm/hr 5.0% fly ash Hydraulic conductivity of sand – fly ash mix.

EWRI – Kansas City Plantings  Wet and dry tolerant  No nitrogen fixers  No invasive species  Low-maintenance requirements  Offer a color variety  Plants had to be easily attainable and replaceable  Included some native species in the plant list.

EWRI – Kansas City Lots of discussion about the plants… Plant TypeSurface Area % Trees8 to 10 Shrubs15 to 20 Flowering Perennials1 to 5 Ornamental Grasses10 to 15 Rock Accents1 to 5 Of course, you could just plant grass. Heritage River Birch

EWRI – Kansas City Constructed Cells Land Use Drainage Area (acres) Volume (m3) Elm Creek PlazaPaved Lendonwood GardensTurf Grove High SchoolPaved Grand Lake Association Turf & Paved Cherokee Queen RiverboatsPaved Spicer ResidenceTurf Clark ResidenceTurf Early Childhood CenterTurf OSU Botanical Gardens, Cell APaved OSU Botanical Gardens, Cell BPaved

EWRI – Kansas City Construction

EWRI – Kansas City Construction costs $7,500 + $51* volume $1,600 * $47 * volume

EWRI – Kansas City Mixing fly ash proved difficult

EWRI – Kansas City Wide distribution in fly ash

EWRI – Kansas City Hydraulic testing

EWRI – Kansas City % reduction in peak flow

EWRI – Kansas City Water Quality Data are Inconclusive  Water quality data collected to date are generally inadequate to draw strong conclusions.  Problems arise due to the long response time of these cells and the difficultly of measuring both inflows and outflows over extended periods.  Long-term, we will take core samples of the cells and determine the species and quantity of pollutants trapped.  A comparison between the fly ash and sand filter control is possible for the initial operation.

EWRI – Kansas City Impact of fly ash on effluent ParameterCellNMeanSt Dev pHControl Fly Ash NO3-N (mg/l) Control Fly Ash Ortho-P (mg/l) Control Fly Ash Fe (mg/l) Control Fly Ash Cu (mg/l) Control8< Fly Ash Pb (mg/l) Control8< Fly Ash6<

EWRI – Kansas City Two-sample T-test (95%) ParameterT-ValueP-ValueDF Significant Difference? pH Yes (Higher) NO3-N No Ortho-P Yes (Lower) Fe No Cu Yes (Higher) Pb No

EWRI – Kansas City Next steps  Finish analysis of cell hydrology.  Quantify impact of the spatial variability in conductivity.  Perform more field tests.  Model results.  Relate to watershed hydrology.  Sample cells to determine retention of pollutants.  Explore filter additives that will reduce N.

EWRI – Kansas City Acknowledgements  Funding for this project was provided by the Oklahoma Conservation Commission as part of a U.S. EPA Region VI, 319h grant.  Fly ash donated by Grand River Dam Authority.  Modeling by Reid Christianson

EWRI – Kansas City