Expediting VI Assessments & Remedies with High Res Data

Transcription

1 TCE Expediting VI Assessments & Remedies with High Res Data TCE Blayne Hartman Ph.D. AEHS San Diego March Mark Kram, Ph.D. Cliff Frescura Presented at AEHS Conference in San Diego in March 2018 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 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 Brief System Description Expediting VOC Entry Points 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 Expedited Source Identification Identify VOC Entry Points Source from VI vs Indoor Unexpected VOCs Superior to Hapsite Screening Much more data collected over time More robust; less downtime No more expensive Another common application of the system is to locate VOC entry points into buildings. Why not just due this with grab samples using an instrument such as a Hapsite? Well you can, but we are finding that at most sites, there is a significant variation in indoor air concentrations over the course of hours. If that is the case, then a single screening measurement at a location may miss a potential exceedance. But with Vaporsafe, the system can monitor multiple locations overnight giving a much more representative dataset identifying VOC entry points. And, it is no more expensive than 8 hours of screening with another instrument.

9 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.

10 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 10 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 within days. This will allow implementation of a remedy and can possibly eliminate the need for a future sampling round. 10

11 Short-Term TCE Assessment Options Time-Integrated Sample One number over sampling period No real-time feedback Costly if multiple rooms, multiple events Can t see the pattern Continuous Analyzers Can determine duration: hours? Days? Long Term Passive/Canister Can see the pattern! Day vs night? HVAC? There are 2 options for assessing the short-term TCE exposure. One is to collect a sample over a period of time, such as a 21 day exposure period. However time-averaged samples have serious limitations, such as incorrect exposure period for non-residential receptors, no resolution (only 1 data point) and no real-time feedback. If the exposure period of concern is 24 hours or a few days, these samples also become prohibitively expensive. The second option is to use continuous analyzers. Continuous analyzers offer many benefits over long-term average samples, especially the ability to recognize the concentration pattern over time.

12 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 Indoor air 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.

13 Print Shop Air - PCE June Office Area (P2) ug/m PCE Run # 14 days of PCE concentrations inside the Print Shop: every night values increased, but were low during the day. The pattern allowed the determination that the increased PCE values at night were due to the HVAC system (perhaps less positive pressure at night when the system ran at a reduced rate?). Further, the continuous monitoring showed that values were below allowable levels during the period when people were working.

14 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 you have no opportunity to try and determine cause-and-effect.

15 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. 15

16 Freon 11 - Office Bldg 2 Days Freon-11 in indoor air over 48 hours in the office building. The pattern repeats itself. 16

17 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. 17

18 Temporal Variation SD Facility 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?

19 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. Knowing these patterns, remedies can be designed and implemented. 19

20 Former Dry Cleaner PCE BP WS 20 Indoor air PCE concentration, barometric pressure and wind speed from a former dry cleaner converted to a retail office building over a 3-day period. The large increase in PCE seems to correlate with a drop in barometric pressure and an increase in wind speed. 20

21 Former Dry Cleaner - Bathroom Indoor air PCE concentrations in the bathroom in the same building. The flat periods occurred at night when the building was empty. Every morning the values increased when the bathroom was being used. The increases were likely due to turning on the exhaust fan in the bathroom. Again, the concentration pattern enabled the cause to be determined. 21

22 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. This concentration pattern enabled the conclusion that the TCE was from an indoor source, which was later identified. Without the concentration pattern, this conclusion could never have been reached.

23 Expedited VI Remedies Can try various remedies & see effects HVAC modifications Fans on/off Air filtration units Sealing sumps & cracks Can put VI Issue to Rest in Days Rather than Months or Years!! 23 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. This is huge for real estate transactions where time is money. 23

24 TCE Urgent Response Options Air Filtration Costs ~ $1,000/unit Sealing Floor Cracks Hard to find them all Relocate People Could open Pandora s box HVAC Modification How to know if effective? Continuously Monitor Determine how often above target level See what remedies are effective Many EPA Regions & State agencies have set urgent response levels. If the levels are exceeded, you are tasked to take some corrective action within a few days! These are some of the options if urgent response is needed. Continuous monitoring enables one to determine which remedy can get the job done.

25 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 within hours that this remedy was effective. 25

26 Large Industrial Facility - SD SVE Remedial Confirmation Pre-SVE Active-SVE 5 days The same San Diego facility shown previously prior to start-up of an SVE and after start-up of the SVE. Proof positive of system effectiveness. 26

27 Proving the Effectiveness of a Remedy TCE indoor air concentrations at 4 locations in an operating facility. Note instant drop in indoor air concentrations to levels that were protective when the mitigation system was started-up. This pattern was recognized within a few hours.

28 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? 28

29 9 8 Remedy Evaluation TCE (ug/m 3 ) Master -Bedroom Home vs. Run ~30 # Days Air Filtration Units Off On SSD On SSD Off /12/16 9/24/16 10/16/16 TCE in the same master bedroom over 30 days. Air filtration units turned off after a few days, then the SSD turned off about a week later. Note that the mean TCE concentration while the air filtration units & SSD were operative was 1.9 ug/m3, then jumped to 4.2 ug/m3 when the air filtration units were turned off but the SSD was operating. Once the SSD was turned off, the mean concentration dropped to 2.6 ug/m3. The key point is that the SSD system operation resulted in higher mean and peak concentrations! The daily oscillation correlated perfectly with wind speed. None of this would have been recognized without high resolution monitoring data. 29

30 TCE Trailer 1 st Floor 40 Trailer 1st Floor Filters On Filters Off 20 TCE TCE indoor air concentrations in a residential trailer. Values ranged from 5 to 15 ug/m3 and showed a sinusoidal pattern. Two high volume air filtration units were turned on which resulted in an immediate drop in concentrdations down to about 5 ug/m3. 30

31 TCE Trailer Shroud 80 Crawl Space Filters On 40 TCE TCE indoor air concentrations in the shroud underneath the residential trailer. Values ranged from 5 to 30 ug/m3 and showed a sinusoidal pattern. Two high volume air filtration units were turned on in the trailer which had no effect on the shroud concentrations. 31

32 Expedited Remediation Remedies Remediation & Mitigation System Monitoring In-Situ GW/Soil Remediation Thermal Heating Sub-Slab Depressurization Systems 32 Vaporsafe can provide data from many locations around a site to demonstrate the effectiveness of remediation systems and building mitigation systems. 32

33 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. 33

34 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 enabled the consultant to take immediate corrective action. 34

35 Summary High Resolution Data Allows Pattern Pattern = Opportunity Opportunity to: Indoor vs Subsurface Source VOC entry locations, preferential pathways Determine Best Remedy Quickly!! Effectiveness of mitigation systems Effectiveness of remediation systems Summary of lessons learned from monitoring projects since March Continuous high frequency monitoring can be implemented during many phases of a vapor intrusion project life-span: initial building evaluation, determining whether mitigation is required, optimizing the remedy and remedy confirmation. Pattern = Opportunity. None of this is possible if the pattern is not recognized.

36 TCE Blayne Hartman, Ph.D. blayne@hartmaneg.com Mark Kram, Ph.D. Cliff Frescura mark.kram@groundswelltech.com TCE