Sustainable Stormwater Research

Transcription

1 2013 NJASLA Designing Healthy Communities Sustainable Stormwater Research Robert G. Traver, Ph.D., PE, D.WRE Professor & Director, Villanova Center for the Advancement of Sustainability in Engineering, Villanova Urban Stormwater Partnership Department of Civil and Environmental Engineering, Villanova University And Dr s Welker, Wadzuk, Komlos and many grad and UG students!

2 The mission of the Villanova Urban Stormwater Partnership is to advance sustainable stormwater management and to foster the development of public and private Partnerships through research on innovative SWM Best Management Practices, Directed Studies, Technology Transfer and Education. 2

3 Stormwater Capture it, Transport it Get it out of the way! First there was drainage... uk.com/historyuk/england History/RomanRoad.jpg

4 China Forbidden City

5 Wingohocking Creek Combined Sewer under construction, 1909 Green City Clean Waters

6 Prior to 1978 Pa Code Drainage May not divert or obstruct natural flow of a watercourse to the injury of another In urban areas,.. Can obstruct sheet flow if done in a non negligent fashion. Can not reasonably change the quality or quantity in a natural channel Shopping centers reasonable precautions

7 1978 PA ACT 167 Peak Flows Limited to Preconstruction Levels 24 hour extreme events single peak year All Points Leaving Site Municipal Implementation Individual site downstream property line Detention / Retention Basins

8 State of the Practice? Detention Only Routing and Computer Power Maintenance? Ownership Rational vs TR 55 8

9 L1 9 Next?... What about Quality?

10 Rain Gardens 1983 (From The Bioretention Manual, Prince George's County, Maryland)

11 Revolutionary Change Goals: xxx 1970 s Nuisance Drainage Goals: Property/Safety Based Drainage Flooding (Detention) Goals: Future? Sustainability Ancillary Benefits SCM BMP Goals: Now? Property/Safety Based Drainage Flooding Receiving Water Based Water Quality & Temperature Surface Water Groundwater Stream Channel Geomorphology Base Flow

12 Philadelphia Water Department Green City Clean Waters Thanks to PWD

13 Philadelphia Green Thanks to PWD 13

14 To do this right, we need to understand how they work

15 Rainfall (inches) Chadds Ford Depth (in.) event Per Year 28 events > 0.5 in 12 events > 1.0 in 6 events > 1.5 in ( ) 15

16 Philadelphia Water Department Percent less then Percent Storm Percent Capture Rainfall 16

17 Villanova s BMP SCM Research and Demonstration Park 17

18 Villanova s BMP SCM Research and Demonstration Park Green Roof 18

19 Villanova s BMP SCM Research and Demonstration Park Bio Infiltration (12 14?) Bio Retention (1) Bio Swale (1) 19

20 Villanova s BMP SCM Research and Demonstration Park Porous Pavements Infiltration Trenches 20

21 Stormwater Wetlands 21

22 Hydrologic Rainfall / Temp. Inflow Outflow Surface Subsurface Level Soil Moisture Water Quality First Flush Grab Samples Automated Lysimeters BioInfiltration Monitoring Interests 22

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26 Traffic Island Surface Water Analysis Lifetime Totals # of Storms Inflow Outflow Removal Efficiency Water Quantity (All Events > 0.25") Water Quantity (Events with Hydrology Measured) ,381,067 L 11,325,457 L 47.0% Water Quantity (Events with Quality and Hydrology Measured)* 116 8,143,140 L 5,017,837 L 38.4% Water Quantitiy (Events <=1.6") 298 8,111,677 L 1,102,204 L 86.4% Total Suspended Solids (TSS) kg 123 kg 93.2% Total Dissolved Solids (TDS) kg 171 kg 84.9% Total Nitrogen (TN) as N g 630 g 83.2% Total Kjeldahl Nitrogen (TKN) as N g 1479 g 69.3% NO2 as N g 258 g 56.5% NO3 as N g 569 g 79.0% Total Phosphorus (TP) as P g 4250 g 47.0% Total Kjeldahl Phosphorus (TKP) as P Phosphate (PO4) as P g 1255 g 59.6% Chloride (CHL) kg 122 kg 58.9% Total Cadmium mg 9556 mg 70.8% Total Chromium mg mg 71.2% Total Copper mg mg 39.0% Total Lead mg mg 91.9% *Number of events here could be less than number of sampled events for any particular pollutant because these events are only > 0.25" of rainfall **Assumes Curve Number flow of 98 from impervious surface

27 Peak Flow Exceedence Probabilities Remaining reduced by at LEAST 50% Peak Flow (cms) % chance NO outflow Inflow Outflow cfs =.045 cms Exceedence Probability 1/27/

28 Output from SlopeFinder program 0.5 BioInfiltration Traffic Island Temp. [C] Recession Rate [in/hr] seven point moving average best fit periodic function 0 Y = *Sin(X(days)/55) BTI (4.25 years of data) EMERSON 28

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30 700 Inflow vs. Outflow for All Storm Events Villanova University Outflow Volume (m^3) VTI 1:1 Regression UB LB Regression Slope = 0.96 x_intercept = % CI = Inflow Volume (m^3) Breakpoint 30

31 Bioretention Water Balance Flow Pollutants Evapotranspiration Bowl Surface Storage Infiltration Bowl Overflow Discharge Media Root Zone Lower Media Storage Percolation Underdrain Discharge If present Native Soils Groundwater Baseflow Davis, Traver, Hunt, Brown,, Lee, Olszewski, in review

32 Soil Moisture Definitions Saturation Everything is full! Field Capacity of Soil Moisture above this is drained by gravity Wilting Point Moisture below this cant be extracted by plants Davis, Traver, Hunt, Brown,, Lee, Olszewski, in review

33 Water Availability Effects Example Loamy Sand Media 55.5% Saturation 44.5% Field Capacity 13.6% Wilting Point 8.0% Sat Hyd Conductivity 2.63 /hr 30.9% Volume that drains through gravity 5.6% Volume that drains only by ET

34 Surface Layer Root Zone Lower Media Storage Bioinfiltration No Underdrain Soil Moisture VU Wilting Point 13.8% Not Accessible by Plants Field Capacity 22.2% Start of Gravity Drainage Saturation 43% Start of Hydraulic Conductivity Conclusions Bowl Always Available Root Zone Normally at Wilting Point So Saturation WP is available Lower Media Storage??? Best LMS At Wilting Point Worst Bowl Volume Only Undisturbed Soil Hydrologic Performance of Bioretention Stormwater Control Measures ASCE Journal of Hydrologic Engineering (2011) Allen P. Davis, Robert G. Traver, William F. Hunt, Robert A. Brown, Ryan Lee, and Jennifer M. Olszewski

35 60 50 VTI 1:1 Regression UB Inflow vs. Outflow for All Storm Events Villanova University Regression Slope = 0.96 x_intercept = % CI = 2.4 Outflow Volume (m^3) LOW BAV AVE BAV HIGH BAV Inflow Volume (m^3) 1/27/

36 Bioretention with Underdrain Surface Layer Root Zone (RZMS) Bowl Not normally used (outflow rate has to be lower then inflow) Root Zone Normally at Wilting Point Lower Media Storage Normally at Field Capacity Best Add in Bowl! Worst Root Zone only Ave BAV = RZMS * (Sat WP) + LMS * (Sat FC)) Lower Media Storage (LMS) Low BAV = RZMS * (Sat WP) High BAV = Bowl Vol. + (RZMS*(Sat WP) +LMS * (Sat FC)) Undisturbed Soil Hydrologic Performance of Bioretention Stormwater Control Measures ASCE Journal of Hydrologic Engineering (2011) Allen P. Davis, Robert G. Traver, William F. Hunt, Robert A. Brown, Ryan Lee, and Jennifer M. Olszewski

37 BioRetention w IWS Surface Layer Root Zone Really Depends on Whether the IWS infiltrates or Stays wet! With Permeable Soils Acts as Bioinfiltration WO Perm. Soils Use Bioretention Lower Media Storage Undisturbed Soil Hydrologic Performance of Bioretention Stormwater Control Measures ASCE Journal of Hydrologic Engineering (2011) Allen P. Davis, Robert G. Traver, William F. Hunt, Robert A. Brown, Ryan Lee, and Jennifer M. Olszewski

38 But where does it go? Rain in Rain gone Infiltration ET Dr s Bridget Wadzuk and Robert Traver

39 Evapotranspiration Water transpires from plant leaves and evaporates from the surface of plants and soil Driven by energy Heat (via solar radiation) Temperature Water vapor pressure gradient, wind speed, plant and soil characteristics are also key components that drive ET Source: 39

40 Weighing Lysimeters

41 Design Bioretention with an underdrain 76 cm diameter 91 cm soil depth Bioretention with an internal water storage (IWS) layer 76 cm diameter 61 cm soil depth 15 cm IWS ET Rain Percolation Out Change in Weight

42 Soil Water Characteristic Curve Bioretention with underdrain Created using the Fredlund et al. (2002) approach Weight is indicator for the soil moisture 565 kg Gravimetric water content = 2.6% Soil suction = 100,000 kpa) Wilting point 615 kg Gravimetric water content = 22.8% Soil suction = 10 kpa Field capacity.

43 Total ET, Percolation and Rain (mm) 1/1/2010 2/1/2010 3/1/2010 4/1/2010 5/1/2010 6/1/2010 7/1/2010 8/1/2010 9/1/ /1/ /1/ /1/2010 Average Weight (kg) Total ET, Percolation and Rain (mm) ET Rain Perc Wt Avg /1/2011 2/1/2011 3/1/2011 4/1/2011 5/1/2011 6/1/2011 7/1/2011 8/1/2011 9/1/ /1/ /1/ /1/2011 Average Weight (kg) Bioretention with Underdrain Daily Average 2011 ET 5 mm Percolation 3 mm Daily Average 2010 ET 4 mm Percolation 3 mm ET Rain Perc Wt Avg

44 Bioretention with IWS Total ET, Percolation and Rain (mm) 1/1/2010 2/1/2010 3/1/2010 4/1/2010 5/1/2010 6/1/2010 7/1/2010 8/1/2010 9/1/ /1/ /1/ /1/2010 Average Weight (kg) Total ET, Percolation and Rain (mm) ET Rain Perc Wt Avg Daily Average 2011 ET 6 mm Daily Average 2010 ET 6 mm Percolation 0 mm Percolation 0 mm /1/2011 2/1/2011 3/1/2011 4/1/2011 5/1/2011 6/1/2011 7/1/2011 8/1/2011 9/1/ /1/ /1/ /1/2011 Average Weight (kg) ET Rain Perc Wt Avg

45 When Water is Abundant May data IWS yields more storage > more ET Total Rain, Percolation and ET (mm) Rain Perc ET Under 2011 Under 2010 IWS 2011 IWS

46 Summary Evapotranspiration is a substantial part of the annual budget When water and energy are abundant Bioretention with underdrain ~ 5 mm/day ET Bioretention with IWS ~ 8 mm/day ET Annually Bioretention with underdrain~ 4 mm/d (~ 1.5 m annually) Bioretention with IWS ~ 7 mm/d (~ 2.5 m annually)

47 Lessons Learned We have time to ET soil moisture Not worried about back to back storms We have more capacity for ET then we use. Back to Back? First storm > 1! Second Storm has to exceed available storage 47

48 Now... Back to Back Storms WQ Probability of second events given initial 1" or greater event (avg 14.9/year) PRELIMINARY!!!!!!!!!!!!!!!!!!!!!!!!!!! 4% chance of having 1 or greater any day Probability of having 2 1 storms back to back..04*.03 = 0.1% Probability beginning within 24 hr beginning within 48 hr beginning within 72 hr beginning within 96 hr Probability of having two 1 storms in 3 days.04*.09= 0.4% Probability of having two 1 storms in 4 days.04*.8= 3.3% Now I know why we don t see any effect of back to back storms at VU Secondary Event Rainfall (inches) So if we accept 3% risk of a second storm,...we have plenty of time for ET and or infiltration to empty soil! 48

49 ET Lessons Learned Bioretention We have time to utilize ET Root zone is most productive Not worried about back to back storms We think... (still working) Soil Storage ET is significant as a yearly volume we don t infiltrate it all. If bad soils... We can still remove a significant fraction using root zone and slow release. underdrain with upturned elbow. (yes BILL! IWS!) Roots must reach water! 49

50 Design for ET? 50

51 Design for ET! 51

52 Urban Sidewalk Street Flood overflow To storm sewer Temporary Storage in Rock Bed Above root zone

53 Questions I have... Volume... Or Volume + ET + Base Flow WHY SO FAST? (soil media) ET / BF only instead of Slow release Don t forget Sustainability

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55 CO Establishment of vegetation Construction Global warming potential break even point metric tons CO2 eq over 30 years mt CO2 eq Kevin Flynn 70.0 Year 1/27/

56 Parking Deck (~0.1 ha, 10,000 ft 2 ) (2) Vegetated swale Two rain gardens in series Infiltration trench Six monitoring points Treatment Train

57 The mission of the Villanova Urban Stormwater Partnership is to advance sustainable stormwater management and to foster the development of public and private Partnerships through research on innovative SWM Best Management Practices, Directed Studies, Technology Transfer and Education. 57