Green Infrastructure BMPs. Hydrologic Performance Small Storms

Green Infrastructure BMPs Hydrologic Performance Small Storms Clay Emerson, Ph.D. Princeton Hydro Robert G. Traver, Ph.D., PE Department of Civil and Environmental Engineering Villanova University Director, Villanova Urban Stormwater Partnership www.villanova.edu/vusp 1

Mission Statement The mission of the Villanova Urban Stormwater Partnership is to advance the evolving comprehensive stormwater management field and to foster the development of public and private Partnerships through research on innovative SWM Best Management Practices, Directed Studies, Technology Transfer and Education. Research and directed studies will emphasize comprehensive watershed stormwater management planning, implementation, and evaluation. Technology transfer will provide tools, guidance and education for the professional. Partnership Goal is to promote cooperation amongst the private, public and academic sectors. www.villanova.edu/vusp 2

What is the Objective of Stormwater Management? Protecting Life & lessening Public Health & Safety Risk Reducing Risk of Monetary Damage to Private / Public Property Minimize disruption of Community Affairs Protecting Quality of Surface and Groundwater Enhancement of the Quality of Life in Urban Areas (ASCE Manual of Practice Late 80s) ASCE Code of Ethics Engineers shall hold paramount the safety, health, and welfare of the public and shall strive to comply with the principles of sustainable development in the performance of their professional duties (ASCE 2002) www.villanova.edu/vusp 3

Past Practices Flooding Based Peak Flow Focus Large Long storms Detention Focused www.villanova.edu/vusp 4

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2008 Green Infrastructure Goals Flooding Water Quality Surface Water Groundwater Stream Channel Geomorphology Base Flow Tools Problem Minimization LID Product Substitution Vol Control Infiltration ET Reuse Extended Detention Water Quality www.villanova.edu/vusp 6

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CONCEPT Bioinfiltration Research MIS? Perceptions Mechanisms What We Learned www.villanova.edu/vusp 8

Brandywine River Runoff 6.5 15% ET Base Flow 14 (.25 ) 30% 24.6 - (1.25 ) 55% www.villanova.edu/vusp 9

Philadelphia Water Department 1902-2000 Percent less then 100.00 90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 Percent Storm Percent Capture 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 Rainfall www.villanova.edu/vusp 10

Rainfall (inches) 6 5 4 3 2 1 Chadds Ford 1999-2001 Depth (in.) Per Year 28 events > 0.5 in 12 events > 1.0 in 6 events > 1.5 in (1948 2001) 0 1 12 23 34 45 56 67 78 89 100 111 122 133 144 155 166 177 188 199 210 221 23 24 25 26 27 28 event www.villanova.edu/vusp 11

Morphological Characteristics Channel Geometry 1.5 2 year storm Sediment Transport Rate Frequency of Discharge Effective Sediment Transport Maximum Effective Discharge Copied from Loucks River Flow www.villanova.edu/vusp 12

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Bioinfiltration Traffic Island (PA Growing Greener Grant -2001) Watershed 1.3 acres Bowl Size -.3 Watershed Inches -.6 off impervious. NEVER any runoff until over??? Land Use - The watershed includes a student parking lot, roadway and lawn areas. It is approximately 50% impervious. Design.. The island is designed to control smaller storms (1-1.5 inches); infiltrating runoff, reducing downstream stormwater volumes, stream bank erosion, and nonpoint source pollution to the headwaters of the Darby Creek.. www.villanova.edu/vusp 14

BioInfiltration Traffic Island - Watershed 1.3 Ac 46% Imp. - (10:1) www.villanova.edu/vusp 15

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Ultrasonic Level Detector Rain Gage Invert (El 444.25) Weir El 445.20 Soil Moisture Meters Lysimeters www.villanova.edu/vusp 19

Hydrologic Performance 2003 - Traffic Island Volume Cubic Meters 1,400 1,200 1,000 800 600 400 200 Rainfall Volume BMP Inflow BMP Outflow 0 JAN FEB MAR APR 68 % removal of Runoff 88 % removal of Rainfall MAY JUN JUL AUG SEP OCT NOV DEC Average www.villanova.edu/vusp 20

Hydrologic Performance 2004 - Traffic Island Volume Cubic Meters 1,400 1,200 1,000 800 600 400 Rainfall Volume BMP Inflow BMP Outflow 200 0 JAN FEB MAR APR 59 % removal of Runoff 80 % removal of Rainfall MAY JUN JUL AUG SEP OCT NOV DEC Average www.villanova.edu/vusp 21

Hydrologic Performance Volume Cubic Meters 1400 1200 1000 800 600 400 200 0 Rainfall Volume BMP Inflow BMP Outflow 71% removal of Runoff 86% removal of Rainfall Jan Feb Mar Apr May Jun 2005 - Traffic Island Jul Aug Sep Oct Nov Dec Average www.villanova.edu/vusp 22

Example 2005 TI Storm Time Begin Time End Rainfall WF Modeled 77 Events 48 Rainfall (not all snow included) 7 Events Overflowed Yearly Summary 5.5 - Overflow 2.5 Pre (Meadow B) (in) (ft^3) 59 10/6/05 17:35 10/9/05 5:40 6.01 11705 26 4/1/05 22:30 4/3/05 14:20 4.04 4297 46 7/7/05 21:50 7/8/05 13:55 2.2 1272 74 12/15/05 19:40 12/16/05 5:55 2.06 2196 6 1/13/05 22:35 1/14/05 11:50 1.95 2291 15 2/14/05 12:05 2/15/05 1:20 1.95 1967 25 3/27/05 17:45 3/31/05 12:20 1.62 0 38 6/3/05 4:25 6/4/05 9:00 1.54 NA 62 10/21/05 7:25 10/22/05 21:05 1.48 NA 63 10/24/05 17:55 10/26/05 3:45 1.46 NA 56 9/15/05 5:15 9/17/05 19:20 1.32 NA 71 11/29/05 15:50 11/30/05 0:50 1.13 202 24 3/23/05 4:45 3/23/05 22:20 1.06 0 60 10/10/05 8:10 10/14/05 23:05 1.06 0 68 11/21/05 15:45 11/22/05 11:50 1.06 0 3 1/5/05 0:50 1/6/05 17:30 1.05 0 12 2/5/05 14:20 2/7/05 7:00 1.05 0 47 7/15/05 16:10 7/18/05 4:20 1.03 0 www.villanova.edu/vusp 24

William Heasom www.villanova.edu/vusp 25

Output from SlopeFinder program 0.5 BioInfiltration Traffic Island 30 0.4 20 10 0 Temp. [C] Recession Rate [in/hr] 0.3 0.2 0.1 seven point moving average best fit periodic function 0 2003 2004 2005 2006 BTI (4.25 years of data) Y = 0.24-0.058*Sin(X(days)/55) EMERSON www.villanova.edu/vusp 26

October 6-8 th BioInfiltration TI Oct 06, 2005 Storm 447.00 6.02 0 0.1 446.50 0.2 Elevation (ft) 446.00 445.50 445.00 Weir El = 445.92 0.3 0.4 0.5 Rainfall (in/5 min) 0.6 444.50 0.7 444.00 0.8 10/6/05 0:00 10/7/05 0:00 10/8/05 0:00 10/9/05 0:00 10/10/05 0:00 10/11/05 0:00 10/12/05 0:00 Time Bill Heasom www.villanova.edu/vusp Rainfall 27 WS El (Oct Param)

Oct 06, 2005 Rainfall Vs Inflow and Outflow Rainfall (in / 5 min) 2 0 0.02 0.04 Pervious Inflow ( ft^3/sec) 1 1 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0 0.2 10/8/05 0:00 10/8/05 2:24 10/8/05 4:48 10/8/05 7:12 10/8/05 9:36 10/8/05 12:00 10/8/05 14:24 10/8/05 16:48 10/8/05 19:12 10/8/05 21:36 10/9/05 0:00 Bill Heasom Time www.villanova.edu/vusp 28 Inflow Surface outflow Rainfall

GW Mounding? BioInfiltration Traffic Island Groundwater Level Monitoring 431 0.0 MW1 430 MW2 MW4 0.1 Groundwater Elevation (ft) 429 428 Rain 0.2 0.3 Rain (in) 427 0.4 426 8/4 8/6 8/8 8/10 8/12 8/14 8/16 8/18 8/20 8/22 8/24 8/26 8/28 8/30 www.villanova.edu/vusp 29 Date 0.5 Machusick

Sustainable Stormwater Longevity and Maintenance to get there is a FUNDAMENTAL issue! www.villanova.edu/vusp 30

Mis? Perceptions PGC Md, Galli 1993 > 60 Infiltration (mostly trenches) Most not working as designed Listed sediment in pre treatment, location, construction and maintenance (used 72 hour rule to evaluate) Suburban Md Lindsey, Roberts et al. 1992 188 basins (repeat of earlier study) > ½ failed >1/3 sediment buildup www.villanova.edu/vusp 31

Mis? Perceptions Washington State Hilding 1996 Majority working 1/3 had sediment buildup NJ Pine Barrens Princeton Hydro, LLC 2005 47 basins - 70% failed the 72 hour test Two investigated Poor maintenance Designers missed restrictive soil layer So, if you design, locate, construct, and maintain poorly.. It will fail 50% of the time.. www.villanova.edu/vusp 32

Villanova Seepage Pit www.villanova.edu/vusp 33

Villanova Seepage Pit www.villanova.edu/vusp 34

INFILTRATION BMPs Villanova Infiltration BMPs Pervious Concrete Infiltration Basin (PCIB) BioInfiltration Traffic Island (BTI) Infiltration Trench (IT) All BMPs are retrofits and were constructed for research and demonstration purposes and have been the subject of continuous hydrologic monitoring. Emerson 2008

INFILTRATION BMPs Pervious Concrete Infiltration Basin (PCIB) Constructed in 2002 Underground storage beds overlain with pervious concrete. Dormitory rooftops directly connected (piped) to storage beds

INFILTRATION BMPs Pervious Concrete Infiltration Basin (PCIB) Shallow (18 ), underground crushed stone storage beds Depth in lower bed measured using a pressure transducer (~2 year record) Soil moisture content Temperature Rainfall

INFILTRATION BMPs Pervious Concrete Infiltration Basin (PCIB) 1.3 Ac 62% Impervious 6:1 DCIA to BMP (3:1) 270 in/yr (135 in/yr)

INFILTRATION BMPs BioInfiltration Traffic Island (BTI) 1.3 Ac 46% Impervious 10:1 DCIA to BMP 450 in/yr

INFILTRATION BMPs Infiltration Trench (IT) Constructed in 2004 Deep (~6 ft) crushed stone bed Most urban-like retrofit

INFILTRATION BMPs Infiltration Trench (IT) Depth measured using a pressure transducer Rainfall and temperature measurements Intentionally under (poorly) designed

INFILTRATION BMPs Infiltration Trench (IT) 0.47 Ac 100% Impervious 130:1 DCIA to BMP 5,900 in/yr

PERFORMANCE INDICATOR How should the performance of an infiltration BMP be assessed? Annual runoff capture efficiency - Influenced by drainage area characteristics Post storm ponded time - Most regulations include ponded time - 72 hr failure Ponded recession rate - Can be related to physical properties - Direct indication of the infiltration process

PERFORMANCE INDICATOR Ponded Recession Rate Not always constant with depth Each BMP has its own characteristic recession limb (shape) from storm to storm Can be compared over time (longevity)

LONGEVITY BioInfiltration Traffic Island (BTI) 0.5 BioInfiltration Traffic Island 30 0.4 20 10 0 Temp. [C] Recession Rate [in/hr] 0.3 0.2 0.1 seven point moving average best fit periodic function 0 Y = 0.24-0.058*Sin(X(days)/55) 2003 2004 2005 2006

LONGEVITY Pervious Concrete Infiltration Basin (PCIB) Avg. Temp. (C) 30 20 10 0 Pervious Concrete Infiltration Basin Recession Rate (in/hr) 1.0 0.8 0.6 0.4 1.4 to 1.2 ft 1.2 to 1.0 ft 1.0 to 0.8 ft 0.8 to 0.6 ft 0.6 to 0.4 ft 0.4 to 0.2 ft 0.2 to 0.02 ft 0.2 0.0 Jan-04 Apr-04 Jul-04 Oct-04 Jan-05 Apr-05 Jul-05 Oct-05 Jan-06

LONGEVITY Infiltration Trench (IT) 100 Infiltration Trench 30 20 10 Temp. [C] 10 0 (log scale) Incremental Slope [in/hr] 1 0.1 5 to 4 ft 4 to 3 ft 3 to 2 ft 2 to 1 ft 1 to 0.1 ft 0.01 Jul-04 Jan-05 Jul-05 Jan-06 Jul-06 Jan-07

LONGEVITY Only the IT shows visual evidence of a systematic change (decrease) in performance All three BMPs show significant (two-fold) seasonal variation What is the origin of seasonal variation in infiltration BMP performance? Why does only one (IT) show a systematic decrease?

SEASONAL VARIATION What is the origin of seasonal variation? BioInfiltration Traffic Island

SEASONAL VARIATION What is the origin of seasonal variation? Infiltration Trench

SEASONAL VARIATION The viscosity of water varies ~twofold over average annual temp. ranges K = k ρg µ Where: K = hydraulic conductivity [LT -1 ] k = intrinsic permeability [L 2 ] ρ = fluid density [L -1 T -1 ] g = gravitational acc. [LT -2 ] µ = fluid dynamic viscosity [ML -1 T -1 ]

SEASONAL VARIATION Hydraulic Conductivity [in/hr] 0.60 0.40 0.20 Summary of Regressions Observed Regression Fluidity Correction Regression Bounds (p=0.05) Infitlration Trench BioInfitlration Traffic Island 4.0E-004 3.0E-004 2.0E-004 1.0E-004 [cm/s] All obs. regressions are significant at the >95% level Predicted variations (viscosity correction) all lie well within the 95% CI of the regressions Pervious Concrete Infiltration Basin 0.00 0 5 10 15 20 25 Temperature [C] 0.0E+000

LONGEVITY Do the PCIB or BTI show any signs of a systematic decrease over time? Multiple linear regressions (temperature & age) Multiple Linear Regression Slope (Temp.) Slope (Age) n in/hr/c -95% +95% in/hr/yr -95% +95% r 2 P PCIB 15 0.0029 0.00093 0.0046 0.030 0.00090 0.060 0.52 0.012 BTI 53 0.0037 0.0015 0.0059 0.0064-0.023 0.035 0.19 0.0046 ( ) n 5 k + 2

LONGEVITY The IT data show undeniable evidence of a decrease over time. To be fair, the IT data includes first 1.5 yr of operation (PCIB and BTI do not) 100 Infiltration Trench 30 10 Infiltration Trench 30 10 20 10 0 Temp. [C] 8 20 10 Temp. [C] Incremental Slope [in/hr] 1 5 to 4 ft 0.1 4 to 3 ft 3 to 2 ft 2 to 1 ft 1 to 0.1 ft 0.01 Jul-04 Jan-05 Jul-05 Jan-06 Jul-06 Jan-07 Incremental Slope [in/hr] 6 4 5 to 4 ft 4 to 3 ft 3 to 2 ft 2 to 1 ft 1 to 0.1 ft 0 2 0 Jan-06 Jul-06 Jan-07

LONGEVITY What impacts the longevity of infiltration BMPs? There are many processes that tend to decrease the rate of infiltration. There are also many processes and soil characteristics that resist degradation and can improve the overall rate of infiltration. not including native soil profile, depth to groundwater, and construction techniques. Good Not so good Bad

LONGEVITY PCIB Low (3-6:1) ratio of DCIA to BMP area Inflow with characteristically low TSS concentrations Shallow bed Closed bed, no vegetation, mulch, organic matter, or freezethaw.

LONGEVITY IT Extremely high (130:1) ratio of DCIA to BMP area Inflow with characteristically high TSS concentrations Closed bed, no vegetation, mulch, organic matter, or freeze-thaw Deep

LONGEVITY Points to Ponder Re: IT 100 Infiltration Trench 30 PA BMP Manual (~5:1 DCIA to BMP ratio) IT (~130:1) [130 / 5] = 26 26 times the annual sediment load Incremental Slope [in/hr] 10 1 0.1 5 to 4 ft 4 to 3 ft 3 to 2 ft 2 to 1 ft 1 to 0.1 ft 0.01 Jul-04 Jan-05 Jul-05 Jan-06 Jul-06 Jan-07 20 10 0 Temp. [C] ~80 equivalent years of operation

LONGEVITY BTI Heavily vegetated Protective mulch layer High organic matter content in surficial soil Some level of TSS pretreatment Shallow bed Freeze-thaw action Moderate (~10:1) DCIA to BMP ratio

CONCLUSIONS Longevity Only the IT showed evidence of a systematic decrease in performance over the period of record. Careful design and construction techniques can produce infiltration BMPs that will continue to meet their design criteria. Influence of seasonal variation

DESIGN RECOMMENDATIONS Seasonal Variation Seasonal variation should be expected Design should consider the influence of this variation BMP modeling should account for variation Hydraulic conductivity should always be referenced to a temperature The amount of variation is dependant on the soil texture (intrinsic permeability)

?So.. Mechanisims? CONSTRUCTION! DESIGN Soil infiltration capacity? Clogging of Surface Layer / Geotextile How dirty is the site? clogging of Surface Layer? pretreatment? ability to maintain? Depth impact? Impact of Rain / Soil protection? www.villanova.edu/vusp 62

Infiltration Risk Idea Rock Bed ½ Runoff goes to Raingarde 63 Next 1+/- Runoff goes to Rock Bed