What s up in North Carolina: Water Harvesting, Fingerprints, Going

Transcription

1 Chagrin Watershed Partners 18Sep13 What s up in North Carolina: Water Harvesting, Fingerprints, Going After LID, & What s the Disconnect? Bill Hunt, PE, PhD, D.WRE Professor, Extension Specialist & University Faculty Scholar NC State University, Raleigh, NC, USA

2 Special Acknowledgements Kathy DeBusk Jon Page Corinne Wilson Natalie Carmen Ryan Winston Cities of Wilmington, Raleigh, New Bern, Durham Project hosts (Tryon Palace, Regency Partners, River Bend Country Club, NCDOT) Grantors: Clean Water Management Trust Fund, NC DENR 319(h)

3 What s Going on in D.C.? A National Stormwater Rule is Under Review by the OMB Schedule to be released in June 2011, Sept 2011, June 2013, Would require any Phase II Jurisdiction to capture (not just detain) the 85%, 90%, 95%, 98%? Storm Event WFH Hunch: 1.2 to 1.5 inches for communities across NC Look for increase in non pond technology as a result

4 We Bring Engineering to Life

5 Cistern Use Craven Co. Ag Center

6 We Bring Engineering to Life

7 We Bring Engineering to Life

8 Cistern Use Kinston Pub. Util.

9 And then came the Town of Holden Beach, NC We Bring Engineering to Life

10 We Bring Engineering to Life

11 We Bring Engineering to Life

12 We Bring Engineering to Life

13 We Bring Engineering to Life Insert Jack Smith Irrigation

14 Holden Beach Cistern Water Level : Irrigation of Garden n) Water Level (i Rainfa all (in) Aug Aug-05 4-Sep Sep Sep-05 4-Oct Oct Oct-05 Date Mr. Smith Rainfall 0

15 The Key: Passive Release Concept Credit: Phil Reidy

16 This has become a norm in NZ

17 New Bern, NC

18 NC Department of Transportation 202 m 2 roof area Streetsweeping, equipment filling/washing 8,330 L tank

19 Detention Detention volume = 2,275 L (~27mm RF) Retention volume = Retention ti 6,055 L Drawdown time = 3 days

20

21 99,310 L Released 59,740 L Used by NCDOT 82% Volume Reduction

22 Better Performance if Thecapture volume had been the correct water quality volume (38mm v. 28 mm) We would have had more space dedicated to rainfall 28 v. 38 mm?

23 Active Management of RWH SE QLD, Australia

24 Weather Forecasts

25 Pilot Application: Tryon Palace 25,000 L 300 m 2

26

27 Location for Irrigation

28 Internet Gateway (Powered by iobridge) Cisterns Overflows from Tanks Automatic Drain Valve Irrigation Pump

29 Discharge Location

30 Tryon Palace Dashboard System Behavior Week of 4/5/ :52 AM

31 Hurricane Sandy (10/29/12)

32

33 Tryon Palace Results Runoff Volume Reduction (%) 91% Average Peak Flow Reduction (%) 93% Overflow Frequency (%) 18% Volume Used (gal) 9,658 Drawdown Volume (gal) 23,414 Volume Released During Rainfall (%) 4% Demand Events Satisfied (%) 100%

34 Also major changes to RWH Irrigation Recommendations

35 Revised Rainwater Harvester Model

36 Fingerprinting Retrofits Wilmington

37 SCMs: Construction: BRCs Crowned Centerline South BRC in LID Catchment

38 SCMs: Permeable Pavement Flow Diverters

39 SCMs: Filterra Unit

40 BRC Filterra Outlet TIA decreased from 60% to 58% DCIA decreased from 24% to 12% PP I PP II N 100 Photo Credit: Google Earth

41 Monitoring Design Paired watershed study 1,2 Two watersheds, two monitoring periods Analysis of covariance (ANCOVA) Least Squared Means (LSM) Quantify change Period Calibratio n Catchment LID Control No SCMs No SCMs Treatment SCMs No SCMs Data Collection V notch weirs and weir boxes Record stage: Q P P, T L L, RO D and C R Flow weighted water quality samples collected: TSS, TKN, TAN, NO 2 3 N, TP, O PO 3, 4, Cu, Pb, Zn 1 Clausen and Spooner, 1993; 2 Grabow et al., 1999

42 Results: Runoff Depth (RO D ) Calibration Treatment Runoff Depth ANCOVA No impact at greater values of RO D Log(LID Runoff Dep pth) (mm) Y C Y T LSM Difference = 52% Greater decrease at lower values of RO D Log(Control Runoff Depth) (mm)

43 Flow diverters Results: Runoff Depth (RO D ) Overwhelmed during intense storms, only 16 mm tall (0.6 in) Little to no capture of runoff for 39% of DCIA Clogged permeable pavement Permeable pavement maintained i approximately every 4 months Bean et al. (2007): Infiltration rates reduced dby three orders of magnitude, from 20,000 mm/hr to 80 mm/hr

44 Results: Runoff Threshold (RO T ) ff Depth (mm) Runof X=5.2 mm LID Runoff Threshold y = x R² = % greater Rainfall Depth (mm) ff Depth (mm) Runof X=3.5 mm Control Runoff Threshold y = x R² = Rainfall Depth (mm) RO T : Minimumrainfall depth that generates runoff Hood et al. (2007): LID Residential: 6.0 mm Untreated Residential: 3.0 mm

45 Results: Runoff Coefficient (C R ) C R : fraction of rainfall converted to runoff NC Undeveloped NC Residential C R RO Measured R P Measured LID Residential LID Treatment 0.18 Post retrofit, LIDC R decreased 47% LID Calibration 0.38 Hood et at. (2007): LID C R =0.07 Control Hood et al., 2007; Line et al., 2002; Line and White, 2007

46 Results: Nutrient and Sediment Loads Nutrient and sediment export rates (kg/ha/yr) Stationti C R n TKN TAN NO 2,3 NN TSS O PO 3 4 TP Control LID Calibration LID Treatment LSM Difference 78%* 61%* 46% 91%* 55%* 73%* LID Residential NC Residential NC Undeveloped *Statistically significant change

47 Going After It in Raleigh Low Impact Development Site (Market at Colonnade) hectares - 84% Impervious - Treatment via ISMP Conventional Development Site hectares - 65% Impervious - Treatment via Dry Detention Sources: Google Maps

48 Site Layout: LID Underground detention/infiltration system

49 LID: How it Works Grocery Store Infiltration Gallery Detention ti Chamber (not to scale)

50 Site Layout: Conventional Dry Detention Basin

51 Hydrology: Runoff Depth Rainfall/ /Runoff De epth (mm) Julian Day Rainfall 30.6 LID Inflow 20.3 Conv. Inflow 18.4 Conv. Outflow LID Outflow 0.6 Rainfall Conv. -Inflow Conv. -Outflow LID-Inflow Inflow LID-Outflow

52 Hydrology: Runoff Coefficient This study 0.49 Conventional Development Line et al. (2012) 0.44 Hood et al. (2007) Rushton (2001) This study 0.02 LID Line et al. (2012) 0.58 Hood et al. (2007) 0.07 Rushton (2001)

53 Hydrology: Peak Discharge 7/28/12 Storm Da ate 7/21/12 7/4/ Peak Discharge Depth (mm/hr) Predevelopment No Treatment Conventional Development LID

54 Water Quality: Loading Conv. LID Conv./LID Ratio TN (kg/ha/year) TP (kg/ha/year) TSS (kg/ha/year) Neuse TMDL LID Conventional Development LID (Line et al., 2012) Conventional Dev. (Line et al., 2012) TN Loading (kg/ha/year)

55 Falls Lake Jordan Lake

56 Downspout Disconnection (DSD) Item Sample Budget Cost (Lowes) 10 of 4 $6.22 corrugated pipe Subtotal Converter $9.51 $15.73 Joint Screws $3.97 $19.70 Hacksaw $16.98 $ Splash block $6.57 $43.25

57 Construction

58 4 SLOPE A B Slope (%) Length (ft) Roof Area (sf) Infiltration rate (cm/hr) B A

59 1 LENGTH A B Slope (%) Length (ft) Roof Area (sf) Infiltration rate (cm/hr) A B

60 2 LENGTH A B Slope (%) Length (ft) 5 10 Roof Area (sf) Infiltration rate (cm/hr) A B

61 3 AREA A B Slope (%) Length (ft) Roof Area (sf) Infiltration rate (cm/hr) A B

62 1 Low Volume Threshold 150 A B ume per st torm (cf) 100 Cumulative % Reduction A Slope (%) Length (ft) Roof Area (sf) Infiltration rate (cm/hr) B Outflow vol Inflow volume per storm (cf)

63 2 Similar Behavior 30 ume per st torm (cf) 20 A Slope (%) Length (ft) 5 10 Roof Area (sf) Infiltration rate (cm/hr) B Outflow vol 10 A B Cumulative % Reduction Inflow volume per storm (cf)

64 3 Strong Difference A B ume per st torm (cf) Cumulative % Reduction A Slope (%) Length (ft) Roof Area (sf) Infiltration rate (cm/hr) B Outflow vol Inflow volume per storm (cf)

65 4 Clear Difference ume per st torm (cf) Cumulative % Reduction A B A Slope (%) Length (ft) Roof Area (sf) Infiltration rate (cm/hr) B Outflow vol Inflow volume per storm (cf)

66 Summary of DSD Data Site Mean Percent Cumulative Percent Watershed Ratio Reduction Reduction (contributing: receiving) Length of Run (ft) 1A Slope (%) 1B A B A B A B Mean/ Median 79.9/ / / / / 6.3

67 Conclusions Big Changes to Rainwater Harvesting Design Guidance (incl. new model) Green Roofs, too Fingerprinting Retrofits to coincide with street renovation can make a difference Going all out with Green & Gray Infrastructure can eliminate nearly all runoff even in the Piedmont Simple (Disconnects) can be effective

68 For the Real Storm Geeks Out There First 3 of these studies are newly minted and available for free from NCSU. Best way to get there: Google: NCSU Stormwater Publications Scroll toward bottom & look up: Page, Jonathan Wilson, Corinne DeBusk, Kathy

69 Thanks! Questions?