Greener Alternatives for Storm Water

1. Greener Alternatives for Storm Water Jonathan Stanton Public Health Engineer

2. What are Some Alternatives That Can Be Used for Storm Water Pollutant Removal? • Bioswales • Rain Gardens • Pervious Pavements • Rain Barrels • Bioretention Facilities

3. Bioswales • Bioswales are landscaped elements to remove silt and pollution from surface runoff water • Can remove pollutants from runoff such as sediment turbidity, heavy metals, oil and grease, and other pollutants • Some pollutants are removed by vegetation whereas others are removed by the slowing of flow to allow for settling or biota consumption. • So if we remove the sediment we remove a lot of the pollutants that are attached !! • Bioswales can reduce TSS by 4-19% in general and can

4. Rain Gardens • Rain gardens are shallow depressions in landscape planted with trees, shrubs, and ground cover. • Use layers of mulch, soil, and plant root systems where pollutants such as bacteria, nitrogen, phosphorous, heavy metals, and oil and grease are retained, degraded and absorbed. • Removals can be around: • Total Suspended Solids: 23% - 81% • Total Phosphorus: 38% - 72% • Nitrate (as N): 8% - 80% • Lead: 62% - 91% • Zinc: 63% - 76% • Copper: 53% - 65 • Cost can be around $10-$12 a square foot. Normal residential gardens are typically 100-300 square feet in size.

5. Pervious Pavements • Pavement designed to allow percolation or infiltration of storm water through the surface into the soil below where water can be naturally filtered and pollutants removed. • Removals can be around: • Total Suspended Solids: 95% • Total Phosphorus: 65% • Nitrate (as N): 82% • Metals: 98-99% *Winer 2000 • Cost is approximately 10-15% higher than traditional asphalts or pavements.

6. Rain Barrels • Rain barrels are one of the fastest growing storm water runoff tools and can be used in any residential or commercial application. • Rain barrels are hooked into downspouts to capture all roof rainwater thus removing that water from the storm water system. • A typical rain barrel can collect: • 1” rain event; Roof area of 2400 sq feet • 1 inch * (1 ft/12inches)*2400 sq. ft. * 7.48 gallons/ 1 cubic foot*75% capture rate= 1122 gallons of water captured! • Cost of rain barrel about $80-$100

7. Bioretention Facilities • A bioretention facility promotes infiltration of storm water in order to reduce its volume, improve its quality, and increase groundwater recharge. • The major function of these facilities is to increase the duration of underground ponding. • Removals can be around: • Total Suspended Solids (TSS) 81% • Metals (Cu, Zn, Pb) > 51-71% • Total Phosphorus 29% • Total Kjeldahl Nitrogen 49% • Ammonium 60-80% • Organics 90% • Bacteria 58% • Cost of these facilities can be found by using the equation: • C = 7.30 V0.99 • Where: C = Construction, Design and Permitting Cost ($)V = Volume of water treated by the facility (cubic feet)This amounts to about $6.80 per cubic foot of water storage.

8. Typical layout of these facilities

9. Questions ???