Utilizing Sorbtive Media to Enhance Green Infrastructure Practices. Robert A. Gallucci, PE Imbrium Systems, Inc.

Transcription

1 Utilizing Sorbtive Media to Enhance Green Infrastructure Practices Robert A. Gallucci, PE Imbrium Systems, Inc.

2 Green is Good Why Green Infrastructure? Restores, recycles, extends natural and built infrastructure Vegetative uptake of pollutants Volume reduction through infiltration Volume reduction through evapotranspiration Aesthetically pleasing Energy conservation Provides Habitat Delivers multiple community benefits along with stormwater management Less costly than conventional infrastructure (really?)

3 Phosphorus Recent studies demonstrate green roofs and bioretention filters are sources rather than sinks of phosphorus Green roofs and/or bioretention are ineffective technologies for metals removal from stormwater Several studies noted 10 to 20 fold increases in phosphorus Footnote - Tim Van Seeters, et. al. Eric Camm, University of Waterloo Where is all this phosphorus coming from?

4 Phosphorus Because phosphorus is the limiting nutrient in fresh water bodies, the transfer of phosphorus in stormwater to surface waters may cause eutrophication. Phosphorus limits are in place for: Lake Simcoe Lake Tahoe Finger Lakes in New York State Chesapeake Bay Lake Erie Lake Ontario Coming soon to a lake near you

5 Imbrium Sponsored Field Studies University of Florida University of Waterloo North Carolina State University

6 What is Sorbtive MEDIA? Sorbtive MEDIA an engineered green-tech filtration media designed to capture and retain dissolved phosphorus as well as metals. an oxide coated, high surface area reactive media which achieves extremely low TP effluent concentrations (<0.1 mg/l). has a surface area upwards of m 2 /g. is long lived and effectively removes pollutants even after 22,000 bed volumes. It removes up to 90% TP. a media with a moderate density of 66 lb/ft 3 and 1057 kg/m 3. removes 5.4 mg of phosphorus for every g of media. has a hydraulic conductivity (falling head method) of 0.9 cm/s. is tested under conditions with contact time of 2 minutes. has a surface loading rate of 40 L/min/m 2 and 1 gpm/ft 2.

7 Case Study #1 North Carolina State Biological and Agricultural Engineering Department Soon to be a graduate level thesis Permeable Pavement Design and Research Project Casey and Casey Law Firm in Boone, North Carolina Sponsored by Clean Water Management Trust Fund

8 Case Study #1 3 alternate designs Monitoring includes: Rain gauge Weir box ISCO samples 40 hydraulic events volume reduction 16 runoff events (4 per season) effluent concentrations and loading Began Fall 2010 and ends May 2012

9 Case Study #1 16 Runoff events will be analyzed for: TKN NOx NH 4 TP Zn Cu

10 Case Study #1 Objective Quantify volume and load reduction. Determine if NC DENR should award extra credits for enhanced pavement sections. Determine if Imbrium s WA Sorbtive Media effectively removes phosphorus in this application.

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13 1 1 WA Sorbtive Media

14 Layout

15 Weir Installation Weir Box Installation

16 Monitoring Study Site Description Cell A - Standard Cell B Extra Depth Cell C WA Sorbtive Total Depth of Drainage Layer (in) Depth of Internal Water Storage Layer (in) N/A 12 6 Surface Area (ft 2 ) Hydrologic Summary (4/8/11-8/24/11) Cell A - Standard Cell B Extra Depth Cell C WA Sorbtive Estimated Total Rainfall (in) Estimated Total Rainfall (ft 3 ) Total Outflow from Underdrains (ft 3 ) Outflow as Percentage of Estimated Rainfall 16% 3% 1% Runoff Reduction 84% 97% 99% Max Flowrate (cfs) Average Surface Infiltration Rate (cm/hr) Prepared by Brad Wardynski, NCSU

17 What is WA Sorbtive MEDIA? WA Sorbtive MEDIA is a crushed limestone dust. is mixed with our proprietary additive. is screened to create a specific gradation: Sieve Size % Passing No. 3/8 100 No No No No No No Pan 0

18 Dumping WA Sorbtive MEDIA from Supersack

19 Screeding WA Sorbtive MEDIA over open graded base material

20 Laying pavers on the fully prepared bed

21 Case Study #2 Green Roof Study Research by Eric Camm and Tim Van Seeters University of Waterloo

22 Changes in Hydrology Loading is a function of Volume & Concentration

23 Archetype House Objectives Conduct a field-scale study to investigate: soluble reactive phosphorus (SRP) total phosphorus (TP) ph total dissolved solids (TDS) suspended solids (SS) grain size Stormwater runoff from an existing green roof. Study the ability of the green roof to act as an effective BMP source control for the reduction of stormwater runoff volumes.

24 Archetype House Objectives Determine Sorbtive MEDIA s P-sorption capacity and lifespan Recommend design and logistical considerations for future implementation of engineered media for P removal in green roof and bioretention runoff

25 Experimental Design July 2009 to August 2010 Laboratory Study (equilibrium tests) to evaluate the P sorption capacity to estimate functional lifetime expectancy Field Study (mass balance approach) 26 rainfall events to assess the field performance of the engineered media to remove P in runoff Hydrologic data was collected for 68 rainfall events over 14 months

26 Green Roof Design 180 mm growth medium with fertilizer blended in

27 Green Roof Design Upper roof drains unto green roof No fertilizers added to roof during study

28 Sample Collection inflow sampling location tipping bucket flow gauge outflow sampling location Media volume = 0.079m m height 0.558m diameter Surface loading = 1.4 lps/m2 treatment system

29 Green Roof Design water inflow rain barrel cartridge Qp = 1.14 lps Contact time at peak flow = 69 seconds overflow outflow

30 Phosphorus Removal 2010 Phosphorus Removal Percent Phosphorus Removal Storm Size (mm) May 13 May 2 Jun 3 Jun 12 Jun 16 Jun 22 Jun 24 Jun 26 Jun 24 Jul Storm Date Storm Size SRP Removal TP Removal 0

31 Findings In 2009 the green roof retained 41.5% of rainfall in 2010 retained 53% of rainfall VOLUME REDUCTION IS GOOD translates to load reduction The highest month was 76.5% in August The lowest month was 14.7% in October The green roof is also good for extending lagtime Shift peak to 35 minutes instead of 3 minutes The roof was a net exporter of phosphorus (source?) ph was reduced from 8.22 to 7.56 SRP was reduced from to mg/l

32 Conclusions Sorbtive MEDIA: Reduced SRP loadings by 82.4% and TP loadings by 86.6%. Attains low concentrations of P in stormwater runoff. Displayed no loss of Sorbtive capacity. Media phosphorus removal capacity = 7.71mg/gram Estimated it could last another 153 years. BMPs such as rain gardens, road swales, and stormwater ponds could easily be optimized to improve P removal with Sorbtive media.

33 Green is Good Add real engineering skills and knowledge Engineering community needs to drive the initiative Volume reduction is fundamental to restoring the natural hydrology Treatment technologies that work are fundamental to achieving TMDL goals Volume reduction plus EMC reduction leads to a total reduction in loading to receiving water bodies

34 Thank you for your time! Questions?