Quantifying the First Flush in Rainwater Harvesting Through Continuous Monitoring & Analysis of Stormwater Runoff

Transcription

1 Quantifying the First Flush in Rainwater Harvesting Through Continuous Monitoring & Analysis of Stormwater Runoff Jessica Lay, M.S. Student Dr. Jason Vogel, P.E.; Dr. Jason Belden; Dr. Glenn Brown, P.E.

2 First Flush in Rooftop RWH Majority of a rooftop s dust and debris is believed to be washed away during the first flush Yaziz et al. (1989): 5L/18m 2 galvanized-iron and concrete tile roofs Martinson and Thomas (2005): Each mm of diverted rainwater halves contamination Texas Manual on Rainwater Harvesting (2005): 1 2 gallons/100ft 2 of catchment area Yet to be a universal consensus on what exactly constitutes a first flush

3 Background Bioaccumulating organic compounds found in runoff Polycyclic aromatic hydrocarbons (PAHs) Flame retardants Pyrethroid insecticides Carcinogenic, mutagenic and endocrine disrupting effects in humans and biota Pyrethroid insecticides extremely toxic to aquatic organisms Benzo(a)pyrene Image Sources: ;

4 Objectives 1. Quantify a site-specific first flush by continuous monitoring of contaminants found in the rooftop runoff throughout a storm event. 2. Determine if PAHs, flame retardants and selected pyrethroid insecticides have the potential for longterm accumulation in urban soils irrigated with harvested rain water.

5 Compound List PAHs Naphthalene* 2-Methylnaphthalene Acenaphthylene* Acenaphthene* Fluorene* Anthracene* Fluoranthene* Pyrene* Phenanthrene* Benz(a)anthracene* Chrysene* Benzo(b)fluoranthene* Benzo(k)fluoranthene* Benzo(a)pyrene* Indeno(1,2,3-cd)pyrene* Dibenz(a,h)anthracene* Benzo(g,h,i)perylene* Flame Retardants TCEP TDCP Pyrethroid Insecticides Bifenthrin L-cyhalothrin Cypermethrin 1 Cypermethrin 2 Cypermethrin 3 Cypermethrin 4 Surrogates p-terphenyl d14 DBC TCMX *EPA Priority Pollutant

6 Methodology Continuous and discrete monitoring of 10 storms Simulate 3 rainfall events on constructed roofs Organic compound analyses Solid-Phase Extraction & GC/MS Kouzayha et al., 2011 Conductance, turbidity, TSS, metals, nitrate and bacteria QA/QC Replicate and field blank samples collected at 10% Laboratory blanks and spikes run at 10% of samples

7 OSU OKC Sample 10 storms from three roofs Tar and gravel, m 2 contributing area Metal, m 2 contributing area Asphalt shingle, m 2 contributing area Located 170 & 190 m W of I-44

8 OSU OKC 6712 samplers 24, 1000 ml polypropylene bottles 720 submerged probe flow modules Hydrolab MS5 Water Quality Multiprobe Temperature Specific Conductance Turbidity All meteorology by Oklahoma Mesonet

9 Agronomy Farm 3 simulated rainfall events 18 constructed roofs Galvalume sheeting Asphalt shingle 60 year-old clay tiles Replicated in triplicate; oriented N-S, E-W 1.67 m 2 (18 ft 2 ) catchment area Located 300 m N of HW 51 Collect 5, 2 L samples from each roof, combine remaining runoff

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11 Rainfall Simulation Intensity: 2.65 iph Ran simulations for 21 minutes, 21 seconds Based on time to fill all 6 bottles on first simulation Roofing materials experience different runoff volumes Metal > Asphalt Shingle > Clay Tile Collected ~ L of runoff from metal and asphalt shingle roofs; 22L from clay tiles 2L samples equivalent to 2.9 gallons/100ft 2

12 Asphalt Shingle Metal Clay Tile

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15 RL: ng/l

16 RL: 15 ng/l

17 Chlorinated Phosphate Flame Retardant Results Reporting Limit: 30 ng/l 0 indicates below RL A1 C1 M1 A6 C6 M6 Avg. TCEP (ng/l) 0 29* 5.33* Stdev Avg. TDCPP (ng/l) * 5.5* 0 Stdev

18 Organic Compound Analyses No detection of pyrethroid insecticides in first and last samples No detection of any organics in blank samples from rainfall simulator tank QA/QC Surrogates averaged above 80% recovery Average spike recovery between % Based on results, will begin analyzing the 2 nd and 3 rd samples from each roof until no longer detect PAHs/flame retardants

19 1 inch of irrigation water with a nitrate-n content of 1 ppm adds 0.23 pounds N/acre

20 Irrigation Water Suitability 700 μs/cm - None μs/cm - Moderate >3000 μs/cm - Severe

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22 Preliminary Conclusions Initial results suggest atmospheric deposition, not roofing material, is contributor of PAHs and flame retardants in roof runoff Increased potential for soil accumulation of PAHs when watering lawns/gardens with harvested rainwater that has no first-flush diversion

23 Acknowledgements OWRRI/OWRB NSF GRFP Dr. Jason Vogel Dr. Jason Belden Dr. Glenn Brown Field and Lab Work: Grant Graves, Meredith Shiflet, Erin Daly, Alex Tobergte, Aaron Mittelstet, Jeri Fleming, Karl Garbrecht, Haley Malley BAE Lab Manager Wayne Kiner and Staff Oliver Roofing Stillwater, OK Cundiff Custom Fab and Sheet Metal Stillwater, OK

24 Interested in Learning More? Jessica Lay