Expediting Vapor Intrusion Assessments Using High Resolution Continuous Monitoring

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1 Expediting Vapor Intrusion Assessments Using High Resolution Continuous Monitoring EMDQ Workshop - Orlando April 2018 Blayne Hartman Ph.D Presented at EMDQ workshop in Orlando Florida in April Lecture notes are at the bottom of each slide so that if played out as a hardcopy, the presentation can be a useful reference document.

2 The Fundamental Problem with VI Investigations & Solutions Sample Event 1 The Song? Sample Event 2 Are Limited VI Data Any Different? Sample Event #3 The fundamental problem with vapor intrusion assessments is that you are trying to determine whether there is a potential problem with only a few data points. It s like trying to figure out what song you are listening to with only 3 a few short blasts. It can t be done in a time-efficient manner which is why VI investigations can take months or even years to conclude.

3 Presentation Summary System Description QA/QC Details Expediting VI Assessments Expediting VI Remedies Special Treat at the End The following topics will be covered in this presentation.

4 Continuous Monitoring System Sample Inlets 12 High Photo of the Vaporsafe monitoring system. The instrument is about the size of a microwave and can fly around as checked baggage for less than $100.

5 System Capability Fully Quantitative! Can Reach Ultra-Low Levels (<1 ug/m3) for TCE, PCE, Vinyl Chloride & others <10 min Analysis Time for TCE & PCE Multiple Sample Locations (16 to 30) Very Stable - holds calibration for months Real-Time Data - Groundswell Software Discrete Sampling Mode VaporSafe monitoring system capabilities. Fully quantitative (not screening level data), measures the most critical compounds, can do that in 10 minutes and can monitor 16 or more locations. The data are sent to the web after every analysis to a server with a user-friendly interface enabling the client real-time data. The system can also be put in discrete sample mode enabling the user to look for VOC entry points or to collect samples if an unexpected compound occurs.

6 Monitoring of Other Variables BP, Indoor pressure, Differential Pressure Wind Speed, temperature, other climatic Can Turn On-Off 115 V Relays 6 The system also measures barometric pressure, sub-foundation (differential) pressure, and other climatic variables such as temperature. It can accept data from air-monitoring stations and/or from the local airport. Finally, the system can trigger 115 volt relays when VI conditions occur (e.g., indoor air exceedances or sub-foundation pressure increases). These relays can be used to turn on fans, increase the HVAC, open louvers, collect a canister sample and other instant response actions. 6

7 User Friendly Web-Based Data A picture of the user-friendly interface. Contour plots, plots of concentration versus time, stacked plots, and auto-alerts are all available from the dashboard. Plots can be easily exported into a jpeg file or into a ppt for rapid display to interested parties. 7

8 System QA/QC Calibrated with Validated Gas Standards Minimum of 5 Calibration Points Can Run Calibration Gas Every Cycle of Ports Precision on EPA Indy Site: <10% over 100 Days Accuracy vs off-site TO-15: 17% EPA Documented: (EPA/600/R-13/241 June Quality assurance and quality control of the system from the EPA Indy test site.

9 TCA, TCE, PCE Chromatogram (0.2 ppbv) TCE TCA 7 min PCE 9

10 Vinyl Chloride Chromatogram (0.2 ppbv) Vinyl Cl 10

11 Method Detection Limits 15 repetitive analyses Compound Standard Conc MDL (ug/m3) EPA IA RSL* (ug/m3) PCE 1 ppbv TCE 1 ppbv Vinyl Chloride 0.2 ppbv * 1 in 1 million excess cancer risk - residential 11

12 Precision & Accuracy Site Date Range # Analyses Precision (%) Accuracy (%) Oakland (TCE) 2/15/17-12/15/17 (10 months) NH #1 (TCE) 7/15/16-12/17/16 (5 months) NH #2 (TCE) 2/20/18-3/6/ NY #1 (PCE) 11/7/17-12/2/ NY#2 (PCE) 1/10/18-1/19/

13 ECD Calibration Gas Analyses 2 Months Oakland Site 3/15/17 5/19/17

14 Deployment Logistics GC Setup / Security Small footprint (~2 x 2 table required) Some temperature control Can make relatively stealth Sampling Lines Up to 300m from instrument possible Small diameter tubing (1/8 or ¼ ) O&M Conventional Wall Power (115v) Change nitrogen every 3 to 5 months Internet Connectivity Ethernet cable, site Wifi or cellular modem

15 Expedited VI Assessments Can see pattern within days Can determine if from VI or indoor source Can determine cause & effect How often above screening level Pattern = Opportunity 15 Perhaps the greatest benefit of monitoring is the ability to expedite vapor intrusion assessments. Most agencies want a minimum of two indoor air sampling rounds, 6-months apart. But with monitoring data, a temporal pattern can be seen and cause-and effect might be recognized. This will allow implementation of a remedy and can possibly eliminate the need for a future sampling round. 15

16 18 16 VOC Entry Point Determination Room 103 Indoor Air TCE (ug/m 3 ) Door Opened 8:00 am ug/m Room Closed:17: hours Door Closed 8:20 am Time Here s an example of locating VOC entry points in one overnight sampling period. This plot shows indoor air TCE concentrations in a small room after the room was closed up for 15 hours. The continuous increase in TCE indoor air values documented that the room was the entry point for the TCE and the total mass entering the room (mass flux) could be calculated. At 8 am the next morning, the doors to the room were opened and an immediate drop was detected. The doors were closed again at 8:20 and concentrations immediately began to increase again. Imagine doing this at 16 locations in a building. You could readily see which locations showed increases and to what magnitude.

17 Shop Air PCE June 2014 Office Area (P2) 50 PCE Concentration (ug/m3) and Temperature (degrees Celcius) PCE PCE IA Data from First 24 hours 6/6/14 12:00 6/6/14 15:00 6/6/14 18:00 6/6/14 21:00 6/7/14 0:00 6/7/14 3:00 6/7/14 6:00 6/7/14 9:00 Sample Date/Time 6/7/14 12:00 6/7/14 15:00 6/7/14 18:00 6/7/14 21:00 IA data from an operating business in Phoenix in June This plot shows the fist 24 hours of data collected. PCE values increased in the middle of the night from less than 5 ug/m3 up to 30 ug/m3 and then dropped back down in the morning. Cause was unclear.

18 Print Shop Air - PCE June Office Area (P2) ug/m PCE Run # 14 days of PCE concentrations inside an active Print Shop: every night values increased, but were low during the day. It was determined to be due to the HVAC system. But the continuous monitoring showed that values were below allowable levels during the period when people were working.

19 Typical Data After 14 Days 80 Office Area (P2) ug/m ug/m3 PCE Run # The dot in red shows the results if you had deployed a time-averaged sample for 14-days. The single value would have been biased high & indicated a problem. A false positive. But equally important: a single data point does not show you a pattern so that cause-and-effect can be recognized.

20 Freon 11 - Office Bldg 1 Day Freon-11 in indoor air over 24 hours in an office building constructed over a known Freon-11 subsurface source. Large variation (8x) and a strange pattern. 20

21 Freon 11 - Office Bldg 10 Days Freon-11 in indoor air over ~10 days in the office building. The pattern was consistent from day to day and was a result of the HVAC system. 21

22 Temporal Variation 500 Same Time Every Day ug/m tce Six days of continuous monitoring of TCE at another large commercial warehouse in San Diego. The huge increases occur at about the same time every day. What is causing this to happen?

23 Large Industrial Facility Definite Correlation with Differential Pressure Apparent Correlation with Barometric Pressure Comparison of the indoor TCE values to barometric pressure shows an increase in TCE concentrations when there is a drop in barometric pressure (probably due to ocean temperature effects). Comparison of the indoor TCE values to sub-foundation pressure shows a direct correlation between indoor air concentrations to positive pressure under the slab. 23

24 Former Dry Cleaner PCE BP WS 24 24

25 Former Dry Cleaner - Bathroom Night-time Night-time Night-time 25

26 TCE Source Determination Manufacturing Facility TCE TCE :00 pm 7:00 am 7:00 am 5:00 pm 5:00 pm TCE indoor air concentrations in a furniture manufacturing facility. Concentrations were low at night, but then increased during the work day. If vapor intrusion was the source, values should have increased at night when the facility was closed up. The opposite was observed. What was the TCE source?

27 Expedited VI Remedies Can try various remedies & see effects HVAC modifications Fans on/off Air filtration units Sealing sumps & cracks Especially Critical for Short-Term TCE Urgent Response 27 Perhaps the greatest benefit of monitoring is the ability to expedite vapor intrusion assessments. Most agencies want a minimum of two indoor air sampling rounds, 6-months apart. But with monitoring data, a temporal pattern can be seen and cause-and effect might be recognized. This will allow implementation of a remedy and can possibly eliminate the need for a future sampling round. 27

28 Remedy Effectiveness #2 20 Location BZD ug/m3 TCE BZD 24 (ug/m3) vs ug/m /24/17 Run # 3/21/17 Seal Sumps TCE concentrations in a basement at an industrial facility. Values ranged from 4 ug/m3 to 14 ug/m over the 1 month sampling period. But when two floor sumps were sealed up, values crashed to zero within a couple of hours. The monitoring data documented that this remedy was effective. 28

29 Proving the Effectiveness of a Remedy TCE concentrations in 4 locations in an operating facility. Note instant drop in indoor air concentrations when the mitigation system was started-up and to levels that were protective.

30 Remedy Evaluation - Home First 7 days Indoor Air Filtration Units Off TCE indoor air concentrations in the master bedroom over the first week. Values were about 2 ug/m3 and steady when indoor air filtration units and sub-slab depressurization were operative. But 2 ug/m3 is right at the allowed level for a residential exposure, so not low enough to ensure safety. After a few days, the filtration units were turned off and concentrations immediately increased with a daily wave-like pattern. What was going on? 30

31 Residential SSD Evaluation 30 days SSD Off Air filtration units off The same master bedroom after nearly 4 weeks of monitoring. The SSD was turned off after 2 weeks (run #190) and the indoor air concentrations DECREASED!! One conclusion from these data is that actual VOC concentration data are necessary to be sure that a mitigation system is operating effectively. The manometer on the SSD system indicated the system was pulling a vacuum, but clearly was not reducing the TCE levels low enough.

32 TCE Trailer 1 st Floor 40 Trailer 1st Floor Filters On Filters Off 20 TCE

33 Expedited Remediation Remedies Remediation & Mitigation System Monitoring In-Situ GW/Soil Remediation Thermal Heating Sub-Slab Depressurization Systems 33 Vaporsafe can provide data from many locations around a site to demonstrate the effectiveness of remediation systems and building mitigation systems. 33

34 Remediation Monitoring Vinyl Chloride Effluent Location EF 1 Vinyl Chloride 73 ug/m3 60 Vinyl chloride (ug/m3) Energized Before Energized 0 2/27/ /11/17 Run # 3/21/17 Vinyl Chloride in the effluent from a permanganate scrubber located immediately adjacent to a large thermal remediation project. The vinyl chloride concentrations started increasing almost immediately once the electrodes were energized. Vaporsafe data enabled rapid recognition of this situation and enabled the consultant to take immediate corrective action. 34

35 90 80 Remediation Monitoring TCE Indoors Location IA 1 TCE 80 ug/m3 70 TCE (ug/m3) Energized Before Energized Run # 2/27/17 3/11/17 3/21/17 TCE in a warehouse located immediately adjacent to a large thermal remediation project. The TCE concentrations started increasing almost immediately once the electrodes were energized. Vaporsafe data enabled rapid recognition of this situation and and enabled the consultant to take immediate corrective action. 35

36 Summary High Resolution Data Allows Pattern Pattern = Opportunity Opportunity to: Tease out Indoor vs Subsurface Source VOC entry locations, preferential pathways Determine Best Remedy Quickly!! Effectiveness of mitigation systems Effectiveness of remediation systems