420 Not Heated 422 Heated ORD VI-Research Duplex and Wheeler Building, Indianapolis- Summary of Evidence to Date: Temporal Variability in Long-term Mitigation Performance and Before Mitigation: What Causes It? Presented at EPA 2015 workshop on Long-Term Evidence-Based Protection & Sustainability; in Residential, Commercial and Industrial Buildings John Zimmerman and Brian Schumacher US EPA NERL Christopher Lutes CH2M HILL Brian Cosky ARCADIS Inc. Robert Truesdale and Robert Norberg RTI International Office of Research and Development National Exposure Research Laboratory
Duplex Synopsis Indoor and Ambient Air, Passive Samples Locations: ambient; basement & first floor each side 131 rounds of VOC sampling: (Jan 2011-Dec 2014): 1-4 week intervals VOCs by Radiellos Groundwater Multi-depth, short screen wells on two sides of duplex Single depth well completed through basement 2 24 March 2015 Subslab and Soil Gas, Active Samples Five internal soil gas locations, 4 depths each (6, 9, 13, and 16.5 ft). Five conventional sub-slab locations. Four basement wall ports. As many as 110 different days of subslab sampling
Concentration (µg/m 3 ) 100 Mitigation Performance and Temporal Variability: PCE Indoor Air PCE (Passive Sampler Data) 10 1 ~ 2 Orders of Magnitude unmitigated temporal variability Same mitigation system reduced concentrations to ambient in long term test; less variability < 1 OOM 0.1 0.01 01-Jan-11 3 24 March 2015 02-Jul-11 01-Jan-12 Mitigation imperfect and variable in initial on-off tests 02-Jul-12 01-Jan-13 Date 02-Jul-13 01-Jan-14 03-Jul-14 422 First PCE 422 Base S PCE 420 Base S PCE Ambient PCE Mitigation On Mitigation Passive Mitigation On Mitigation Passive
Concentration (µg/m 3 ) 100 10 1 Mitigation Performance and Temporal Variability - Chloroform About 1.5 Orders of Magnitude Unmitigated temporal variability Indoor Air Chloroform (Passive Sampler Data) Mitigation Performance Better When Treatment Sustained Low Long Term Variability 0.1 0.01 01-Jan-11 4 24 March 2015 02-Jul-11 01-Jan-12 02-Jul-12 01-Jan-13 Date 02-Jul-13 01-Jan-14 03-Jul-14 422 First Chloroform 422 Base S Chloroform 420 Base S Chloroform Ambient Chloroform Mitigation On Mitigation Passive
Radon Temporal Variability With and Without Mitigation High Resolution Data with Multiple Averaging Times Long-term Trend With and Without Mitigation Period Blown Up Below Blow-up of Long-term Mitigation Period 5 24 March 2015 1/7-1/10/15 saw 4 day Radon peak; with daily lows as low as -7 F and wind speeds averaging 18 MPH and Max 32 MPH
6 Wheeler Building Mitigation: History 100,000 square foot building Industrial facility from 1911 until 1995. Renovations into live-work lofts, office space and a theater. EPA Research measurements 2009 Sealing and SSD mitigation system was installed in 2010 designed to address highest concentration portion. Subslab VOCs a mix of releases here and upgradient. Premitigation subslab up to 12,000 µg/m 3 TCE Regulator required one round of initial proof of effectiveness through VOC testing (1/11) and differential pressure, then system operation by owner (2011-now) Intensive resampling for 6 months; with 2 week passive winter 2013-2014
Concentration (µg/m3) 9/9/2008 TCE in Indoor Air at Wheeler Building, Pre- and Post-mitigation 1/22/2010 6/6/2011 10/18/2012 3/2/2014 10 1 North End of Wheeler Building A North End Wheeler Bldg B First Floor Prop Room Post-mitigation Building A Post-mitigation Building B Post-mitigation Prop Room Mitigation Start Indiana 30 Year Residential TCE Action Le 0.1 7 Date
Frequently Asked Questions about Duplex Study What is the role of preferential pathways, including sewer lines, in this data set? Are the features of this duplex and other well studied cases typical of the US housing inventory? Is the VOC mass observed entering the duplex primarily from groundwater or vadose zone sources? Why do chloroform and PCE differ at this site, in terms of sources and VI behavior? What is the spatial and temporal variability of the observed attenuation factors? 8
What is the role of preferential pathways, including sewer lines, in duplex data set? 9
10 What is the role of preferential pathways, including sewer lines, in duplex data set?
PCE Soil Gas Spatial Distributions January 2011 August 2011 December 2011 11
What is the role of preferential pathways, including sewer lines, in duplex data set? Results before drain sealing Passive Drain Sampling Data April 13 April 21, 2011 (µg/m 3 ) Location Chloroform TCE PCE 422 laundry drain 1st floor 320 5.6 310 422 bathroom in sink 1.2 0.089 1.4 422 basement floor drain (near furnace) 0.65 0.091 1.7 420 bathroom in sink 1.5 0.054 0.96 420 laundry room drain in floor 1.6 0.087 2.6 12
What is the role of preferential pathways, including sewer lines, in duplex data set? Helium Tracer Test horizontal migration toward the building over distances of up to 20 ft rapid vertical migration from 13 ft to 6 ft. bgs at the injection cluster; typically within 2 days, with and without mitigation. Ground Penetrating Radar (GPR) Survey concrete slab varies from 0.5 to 0.7 ft in thickness irregular undulating contact with the underlying fill material resulting in voids where soil gas may pool or move preferentially. 13
What is the role of preferential pathways, including sewer lines, in duplex data set? Sewer lines and laterals appeared to play some role in contaminant fate and transport in this system; but we have to distinguish multiple scales. Based on the location of the highest PCE concentrations and sewers we suspect they play a role in neighborhood scale transport but we haven t sampled off our lot. Based on the contaminant distribution under the house we suspect that the sewer lateral may have a role in moving mass from the street toward the house. Elevated concentrations of PCE and chloroform were present in the headspace of sewer gas but primarily in one leg; early in the project. Their role as a direct entry pathway through the building envelope were minimized by sealing the drains. 14
15 Are the features of this duplex and other well studied cases typical of the US housing inventory? Compare Indianapolis Duplex and Sun-devil Manor to the 2013 American Housing Survey results (% of 128K units): Location Duplex - Central city (30%) Sun-Devil In MSA but not Central City (50%) Public Sewer - both Duplex and Sun Devil yes (81%) Units in structure Duplex = 2 to 4 units (8%) Sun-Devil = 1 detached unit (65%) Construction date Median in U.S. is 1975 Duplex = Pre 1915 (Pre 1919 is 7% of housing stock) Sun Devil =1991 (1985 to 1995 is 12% of housing stock)
Are the features of this duplex and other well studied cases typical of the US housing inventory? 16 Foundation (survey is % of single family for this variable): Duplex, Basement (full or partial basement = 42%) Sun-Devil Concrete Slab Split Level (slab = 34%) Crawl space (22%) Heating Both Forced Hot Air (64%) Cooling Duplex window units (21%) Sun-Devil central air (65%) Physical Problems 5% of units have moderate to severe problems in one census category Duplex Moderate upkeep problems - Sun Devil no problems
Is the VOC mass entering from groundwater or vadose zone sources?: Henry s Law Comparison Chloroform and PCE: Different Behavior? 17
Is the VOC Mass Entering Primarily From Groundwater or Vadose Zone Sources?: Groundwater Time Sequence Chloroform and PCE: Different Behavior? 18
Concentration (µg/m 3 ) 5000 Is VOC Mass From Groundwater or Vadose Zone?: Soil Gas Time Sequence Subslab Port PCE SSP-1 PCE 500 SSP-4 PCE Mitigation On Mitigation Passive 50 Jan-14 Jul-13 Jan-13 Jul-12 Jan-12 Jul-11 Jan-11 Jul-10 Jan-10
What is the spatial and temporal variability of attenuation factors?: Weekly (Passive Sampler and TO-17 Data) 20
Conclusions Long term mitigation test at the duplex showed that the commercially installed mitigation system worked well in the long term for VOCs; although we observed some short term spikes in concentration. Six months of continuous monitoring at Wheeler showed that a commercial mitigation system on a large mixed use building was providing good protection after 3 years of building owner operations. Sewer line is likely playing a role in transport on the neighborhood and lot scales at the duplex although the building envelope is sealed off. 80% of US homes have sewers. Based on the American Housing survey the two well studied cases are reasonably representative. 21
Conclusions - Continued PCE at the duplex is likely arriving on the property from groundwater depth; but variability in groundwater concentrations does not explain the subslab and indoor variability observed. Mass storage in vadose zone soils may play an important role. Temperature differential was shown to be quite significant in our time series analyses. Chloroform likely has a shallow source, perhaps municipal water/sewer; but may be stripped on the way down to the water table. Average attenuation factors at the duplex vary only modestly over time. 22
More Available: Four Reports Fluctuation of Indoor Radon and VOC Concentrations Due to Seasonal Variations EPA/600/R-12/673; September 2012 (Been Available) Assessment of Mitigation Systems on Vapor Intrusion: Temporal Trends, Attenuation Factors, and Contaminant Migration Routes under Mitigated and Non-mitigated Conditions; EPA/600/R-13/241 (Release expected 3/15) Simple, Efficient, and Rapid Methods to Determine the Potential for Vapor Intrusion into the Home: Temporal Trends, Vapor Intrusion Forecasting, Sampling Strategies, and Contaminant Migration Routes EPA/600/R-14/397 (Release expected 3/15). Future plan will focus on peer reviewed papers first two on Long Term Mitigation and Improved Passive Sampler Performance 23
Contact and Acknowledgements Christopher.lutes@ch2m.com, rst@rti.org or Zimmerman.JohnH@epa.gov The authors thank: U.S. EPA ORD National Exposure Research Laboratory (NERL), Leigh Evans, Doressa Breitfield, and Nate Lichti; Mapleton-Fall Creek Development Corporation Alan Williams and Dale Werkema, US EPA Heidi Hayes and Ausha Scott; Eurofins/Air Toxics Ltd. Robert Uppencamp, Nadine Weinberg, & Rebecca Forbort, ARCADIS David Eskew, OTIE
What is the spatial and temporal variability of attenuation factors?: Daily (On-line GC Data) 25