Effectiveness of Coanda Screens for Removal of Sediment, Nutrients, and Metals from Urban Runoff

Transcription

1 Effectiveness of Coanda Screens for Removal of Sediment, Nutrients, and Metals from Urban Runoff Presented to by Steve Esmond Robbin Webber June 26, 2012

2 Inventor of the Coanda Effect: "A moving stream of fluid in contact with a curved surface will tend to follow the curvature of the surface rather than continue traveling in a straight line." Henri Coanda Romanian inventor Aerodynamics pioneer Builder of world's first jet powered aircraft US Patent No. 2,052,869 Device for Deflecting a Stream of Elastic Fluid Projected into an Elastic Fluid by Henri Coanda, Sept. 1, 1936

3 How the Coanda Effect Works Tilted Wedgewire Screen Technology

4 How the Coanda Effect Works Tilted Wedgewire Screen Technology Wahl, Tony, US Bureau of Water Reclamation, Denver, CO, Hydraulic Performance of Coanda- Effect Screens, Journal of Environmental Engineering Division, ASCE, Vol. 127, No. 6, June 2001,

5 Advantages of Coanda Screens These screens have large flow capacities and are hydraulically self-cleaning without moving parts, so they require minimal maintenance. * * Design Guidance for Coanda-Effect Screens, Report No. R-03-03, U.S. Department of the Interior, Bureau of Reclamation Technical Service Center, Water Resources Services, Denver, Colorado, July 2003.

6 Advantages of Coanda Screens 1. Built with no moving parts 2. Self-cleaning and maintenance-free except for periodic trash pickup 3. Corrosion-resistant 100 percent stainless steel construction 4. Designed to remove 100 percent of trash and sediment at peak flow

7 Curb Inlet BMP Design

8 Curb Inlet Installation

9 Curb Inlet Study Performed by USC Focus on Debris and Sediment Plastics, paper, cans Leaves, sticks, wood chips Mulch, grass, bark, nurdles Sediment, seeds

10 Pollutant Removal USC Study Pollutant Percent Removal Turbidity NTU 79 Dissolved Solids 10 Chemical Oxygen Demand 25 Biochemical Oxygen Demand 25 Total Organic Carbon 25 Total Phosphates -- Total Nitrates 80 Total Iron 72 Zinc 81

11 Debris & Nutrient Removal Rates Two-Year Case Study in Texas Enlarged view of a residential neighborhood draining into a major Dallas water supply lake which suffers from eutrophication

12 Residential Curb Inlet

13 BMP In Service

14 Debris After Removal

15 Debris Collected, Lbs/Ac/Day Debris Collected, lbs per acre p Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09 Jan-10 Feb-10 Mar-10 Date

16 Percent Debris Composition by Wt Debris Composition by Wei 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09 Jan-10 Feb-10 Mar-10 Date

17 Nutrients & Metals Removed in Sediment

18 Sediment vs Debris Sediment 40% Debris 60%

19 Total-N Sediment 26% Debris 74%

20 Total-P Sediment 23% Debris 77%

21 Arsenic Sediment 32% Debris 68%

22 Cadmium Sediment 50% Debris 50%

23 Copper Sediment 25% Debris 75%

24 Lead Sediment 29% Debris 71%

25 Nickel Sediment 28% Debris 72%

26 Zinc Sediment 25% Debris 75%

27 Fecal Coliform Sediment 26% Debris 74%

28 Capture Coefficients kg/km 2 per year Debris Sediment Total Debris 15, ,300 Sediment -0-10,200 10,200 Total-N Total-P Arsenic Cadmium Copper Lead Nickel Zinc

29 Loadings vs. Capture Kg per km 2 per year % Capture Loading Capture Debris 15, % Sediment 10, % Total-N (Lee) % Total-P (Lee) % Arsenic (s) Cadmium (s) Copper (s) % Lead (s) % Nickel (s) Zinc (s) %

30 Sediment Buildup in Lake 1968 Lake Completed, began to fill Cumulative Sediment = 37,960 AF Lake Drainage Area = 1,074 sq.mi. Therefore, the historical Sediment Accumulation Rate = 8,700 kg/km 2 per year. Sediment Capture Coefficient measured in this study was 10,200 kg/km 2 per year.

31 Comparative BMP Performance Pollutant of Concern Biofilters Treatment Control BMP Categories Detention Basins Infiltration Basins Wet Ponds or Wetlands Filtration Hydrodyna mic Separator Systems Coanda Screens Trash & Debris L M/H U U M/H M/H H Sediment Turbidity M/H M/H M/H M/H M/H M/H H Nutrients L M M M M L M Organic Compounds L L U L/M M L L/M Bacteria U U M/H M/H M/H L L/M Oil & grease M/H M/H U U M/H L/M L Pesticides U U U U U L L Legend: L=Low, M=Medium, H=High, U=Unknown. Sources: Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters (1993), National Stormwater Best Management Practices Database )2001), Guide for BMP Selection in Urban Developed Areas (2001), and peer-reviewed field performance data.

32 Capture Efficiency: Conclusion #1 100 percent for both coarse and fine debris, 30 percent for nitrogen, 10 percent for phosphorus, Variable but measureable percentage for metals.

33 Comment on Conclusion #1 On average, 45% of the phosphorus load and up to 50% of the metal (cadmium, copper, zinc) load is present in stormwater in dissolved form. Andrew J. Erickson, PE, Advanced Stormwater Treatment: Dissolved Pollutants, University of Minnesota, St. Anthony Falls Laboratory, Stormwater Magazine, February 2, 2012,

34 Conclusion #2 Fecal Coliform Capture: CFU per sq.km. per year.

35 Conclusion #3 If 5.0 mm particle size is employed as a regulatory standard for trash, then approximately half of the solids, and almost one third of the nutrients and metals, and half of the bacteria, will pass into the environment, carried by particles ranging from 0.5 mm to 5.0 mm.

36 Summary Implementation Costs Installation Cost ~ $1,500 per acre O&M Cost: $150 per ton $20 per acre per year 250 lbs of debris per acre per year

37 Cost To Remove 1 Lb of Sediment & Debris Capital Cost = $1,500 per acre = $101 per acre per year amortized for 20 3%. CC = 101 / 250 = $0.404 per lb. O&M Cost = $150 per ton = $0.075 per lb. Total Cost = = $0.479 per lb.

38 Cost Comparison Structural BMP Cost to Remove 1 Lb of TSS Dredging 1 $ 0.01 Street Sweeping 2 $ 0.11 Coanda $ 0.48 Detention Basin 2 $ 0.63 Sand Filters 2 $ 4.28 Infiltration Basin 2 $ 4.56 Catch Basin Insert 2 $ 4.65 Hydrodynamic Separator 2 $ Paul Pounds, Ft. Worth Water Dept. 5/7/12 Lake Worth Dredging Project 2 Karen Nichols and Hilary Ahrens, What s the Cost to Remove One Pound of Sediment From Stormwater? StormCon 2011

39 Life Cycle LA County - more than 10 years USBR more than 20 years Coanda 30 to 40 years

40 For Further Information Contact: Steve Esmond, PE (714) Robbin Webber (972)