The UNH Stormwater Center NEIWPCC 2007 NPS Conference, Newport, RI May 2007

Transcription

1 LID Stormwater Management Systems Demonstrate Superior Cold Climate Performance than Conventional Stormwater Management Systems Robert M. Roseen, Thomas P. Ballestero, James J. Houle, Pedro Avellaneda, Robert Wildey, Joshua Briggs, Kris Houle, George Fowler NEIWPCC NPS Conference, Newport, RI May

2 Why Stormwater? Water Quality Stormwater runoff is the #1 pollution source, out of fourteen identified non-point sources Shellfishing beds are routinely closed after >1/2 inch of rainfall in 24 hours Contaminated stormwater discharges are responsible for the impairment of one-third of all assessed waters in the United States, according to the EPA. 40% of our rivers, lakes, and estuaries are still too polluted for safe fishing or swimming.

3 Goals for Future SW Control The Primary Cause of WQ Degradation is Altered Hydrology Can be Corrected By LID design: Storm volume reduction through infiltration infiltration thereby replacing lost hydrologic functions from impervious surfaces by reducing hydrologic footprint Water quality treatment by filtration of stormwater through engineered soil media which replaces the lost treatment benefits of natural soils.

4 What is Low Impact Development design (LID)? The GOAL of LID is to preserve pre- development hydrology Runoff Volume Runoff Rate (Peak flow) Groundwater Recharge Stream Base-flow Runoff Water quality The design of SW TX systems using nature as the model Recreate lost hydrologic functions (infiltration, evapotranspiration) ) and to a lesser extent some ecological functions (biodegradation, and adsorption)

5 Pre and Post Development Hydrographs Post-Development Runoff Rate Peak has been knocked down Post-Development Peak Control Pre-Development But sustained high flows continue Courtesy Jeff Dennis, ME DEP, and CEI Time

6 90 Ecological Impacts of Imperviousness and Hydrologic Alterations 80 WATERSHED IMPERVIOUSNESS (%) STREAM IMPACT REDUCTION IN BIODIVERSITY ADAPTED FROM SCHUELER, ET. AL., 1992; USGS SIR

7 LID and the Future During the last census many communities experienced as much as 25% population growth The tremendous growth pressure has municipalities and other watershed stakeholders working to develop strategies for managing growth while maintaining watershed health.

8 LID and Climate Change Recent research examining impacts of climate change on rainfall depths (28-60% increase) demonstrated existing urban infrastructure (culverts) will be under- capacity by 35% There are 2 near-term achievable solutions: Upgrade infrastructure-- --$$$$ Implement wide-scale LID requirements

9 Barriers to Implementation Performance Concerns Cold Climate Long-term term-clogging and durability Water quality performance Construction Challenges Modern design specs Staging Issues: logistics and placement Maintenance Misperceptions Cleaning frequency Snow and ice treatments

10 Dedicated to the protection of water resources through effective stormwater management Research and development of stormwater treatment systems To provide resources to stormwater communities currently involved in design and implementation of Phase II requirements

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12 Hydrodynamic Separator Subsurface Infiltration Unit Filter Unit Porous Asphalt Retention Pond Rip Rap Swale Gravel Wetland Sand Filter Bioretention Unit Tree Filter

13 Seasonal Monitoring

14 Filter Media Frost Penetration 1/13/2005 1/25/2005 2/4/2005 2/16/2005 2/25/2005 3/8/2005 3/15/2005 3/28/ Frost Depth (cm) Temp (C) Sand filter Bioretention I Gravel Wetland Rain Ave. Temp -30

15 Surface infiltration rates for the porous asphalt 11/04-10/06 10/06 Surface Inf. Rate (in/hr) 2,500 2,000 1,500 1, Point A Point B Point C 10/1/04 12/31/04 4/1/05 7/1/05 10/1/05 12/31/05 4/1/06 7/2/06 10/1/06 Date ; 2,500 Even with 99% clogging the IR=10 in/hr > most sands 500 & soils 2,000 1,500 1,000 0 A B C Point

16 Salt Reduction and Porous Asphalt DMA 1-HR AFTER PLOWING, 11AM -4*C PA 1-HR AFTER PLOWING, 11 AM -4*C

17 Salt Reduction and Porous Asphalt Weighted Skid Resistance (BPN) DMA1-100% DMA2-50% DMA3-25% DMA4-0% PA1-100% PA2-50% PA3-25% PA4-0% Study Area

18 Cold Climate Performance Results

19 Performance Efficiencies Filtration/Infiltration Bioretention 2 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% TS S TP H-D DIN Zn TP Summer Winter Annual Gravel 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% TS S TP H-D DIN Zn TP Summer W inter Annual

20 Performance Efficiencies Filtration/Infiltration 100% 90% Flow (gpm) 80% 70% 60% 50% 40% 30% 20% 10% 0% Pourous Asphalt DMA PA ,000 1,500 Time (min) TSS TPH-D DIN Zn TP Precip (in) Summer Winter Annual ADS Subsurface Infiltration 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% TS S TP H-D DIN Zn TP Summer W inter Annual Summer W inter Annual

21 Performance Efficiencies -Conventional Swale 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% TS S TP H-D DIN Zn TP Summer Winter Annual Vegetated Swale 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% TS S TP H-D DIN Zn TP Summer Winter Annual

22 Performance Efficiencies -Conventional Hydrodynamic Separators 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% TS S TP H-D DIN Zn TP Summer Winter Annual Settling Velocity [cm/s] T = 30 C FreshW ater T = 0 C Hi [Cl] Stormwater The effect of T and [Cl - ] is to nearly double the settling time from 1.6 to 3.4 cm/sec *Oberts (2003 ), Jokela (1990) Particle Diam e te r [m icrons ]

23 Particle size distribution for influent vs. sediments captured within hydrodynamic separators Median HS Total Capture Particle Diameter (mm) % Finer

24 Sediment Size Removal Influent PSD Range D for N=8 Storms by Total Capture Gravel Wetland Effluent PSD Range D for N=2 Storms by Total Capture Bioretention Effluent PSD Range D for N=2 Storms by Total Capture Dimension (mm) Dimension (mm) Dimension (mm) D15 D50 D85 D15 D50 D85 D15 D50 D85

25 MTEC ME So What Really Bugs You? MPAC MPAC

26 NH Shellfishing beds are closed after >1/4 inch of rainfall in 24 hours

27 Bacterial Concentrations for Structural Systems Maximum Enterococci (cfu/100ml) % 72 Median 25% 4 4 Minimum 1 INF SF W DP BA GW RLS Key

28 Bacterial Concentrations for Manufactured Systems Maximum 1000 Enterococci (cfu/100ml) % Median 25% 4 Minimum INF W QI SFC HS ID Key

29 LID Site Design, Does it Really Work? Jordan Cove Project, USEPA Funded Dr Jack Clausen and Dr Michael Dietz

30 LID Design Results for Runoff Depth-- Jordan Cove Yearly runoff depth (cm) R 2 = 0.02 R 2 = Total impervious area (%) Traditional LID LID Traditional Courtesy of Mike Dietz, NEMO

31 LID Design Results for TN Export -- Jordan Cove TN export (kg/ha/yr) R 2 = 0.08 R 2 = 0.92 Traditional LID LID Traditional Total impervious area (%) Courtesy of Mike Dietz, NEMO

32 Summary Conclusions LID designs have a high level of functionality during winter months and frozen filter media does not reduce performance Infiltration and filtration systems have the highest removal efficiency It is interesting to note that many of the systems used routinely, without concern for reduced winter performance, are showing otherwise. Future designs focusing on the use of : Storm volume reduction through infiltration Water quality treatment by filtration Will addresses the primary cause of water quality degradation

33 Acknowledgements Funding Source: Manufacturers: Hydro International, Stormtech, CONTECH, ADS, CDS, Environment 21, AquaShield

34 Questions? View of Mt Washington by moonlight 2/06 from Mt Zealand, NH