IMPROVED INVESTIGATION METHODS TO DISTINGUISH VAPOR INTRUSION FROM - PowerPoint PPT Presentation

IMPROVED INVESTIGATION METHODS TO DISTINGUISH VAPOR INTRUSION FROM INDOOR SOURCES OF VOCS Thomas E. McHugh GSI Environmental, Inc. FRTR General Meeting November 10, 2009

PROBLEM: INDOOR SOURCES ■ At vapor intrusion site, testing of indoor air is most direct way to identify VI impacts. VOCs in ■ Indoor sources of VOCs Indoor Air are ubiquitous: cleaners, glues, plastic, etc ■ Detection of VOCs in indoor air does not necessarily indicate vapor intrusion. Critical need for reliable methods to Critical need for reliable methods to Key distinguish between vapor intrusion and distinguish between vapor intrusion and Point: indoor sources of VOCs. indoor sources of VOCs. 2

Bkgrnd Bkgrnd 2004 Background vs. Air Air USEPA Risk-Based Limits Clean GW BENZENE PCE Reported Background Concentration (ug/m 3 ) 100 10 Indoor 1 90 th % Ambient 1 Indoor 1 90 th % 90 th % 10 1 Ambient 1 Median Range of 90 th % Median Median 10 th % Median 10 th % 1 0.1 10 th % 10 th % INDOOR LIMIT 2 INDOOR AIR LIMIT 2 0.1 0.01 0 0.2 0.4 0.6 0.8 1 1.2 0 0.2 0.4 0.6 0.8 1 1.2 Background indoor and outdoor air KEY concentrations commonly exceed risk-based limits POINT: for indoor air. 1) Background concentrations from Sexton et al. 2004 ES&T 38(2); 423-430. 3 2) USEPA Master Screening Values Table, September 2008 3

Consumer Products Containing PCE PCE Product Concentration ARAMCO Art and Crafts Goop Not Specified Aleenes Patio & Garden Adhesive 70% Gumout Brake Cleaner 50 - 90% Liquid Wrench Lubricant w/ Teflon 65 - 80% Plumbers Goop Adhesive 67.5% Hagerty Silversmith Spray Polish 30.5% Champion Spot it Gone 20 - 25% KEY Wide variety of consumer products still contain high POINT: concentrations of PCE. 4 Source: http://householdproducts.nlm.nih.gov/cgi-bin/household/brands?tbl=chem&id=177 4

New Indoor Source of 1,2-DCA DETECTION FREQUENCY CONCENTRATION Median 1,2-DCA Conc. 1,2-DCA Concentration 90%ile 1,2-DCA Conc. 1,2-DCA Detection Frequency (%) USEPA INDOOR AIR LIMIT (ug/m 3 ) <0.08 <0.08 <0.08 Indoor concentration of 1,2-DCA increasing over KEY time. New indoor source = molded plastic POINT: (e.g., toys, Christmas decorations). Note: 1) 1,2-DCA = 1,2-dichloroethane 2) Indoor 1,2-DCA data from residential area in Colorado. Data provided by Jeff Kurtz, Envirogroup (jkurtz@envirogroup.com) Reference: Doucette, Hall, and Gorder, 2010, “Emission of 1,2-dichloroethane from holiday decorations as a 5 source of indoor air contamination”, accepted for publication in GWMR.

SOLUTION: TEST METHODS POTENTIAL METHODS TO DISTINGUISH BETWEEN VAPOR INTRUSION AND INDOOR SOURCES OF VOCS ■ Real-time Used successfully by EPA and Hill AFB Real-time On-site ■ Requires expensive equipment: Hapsite On-site Analysis Analysis GC/MS or USEPA TAGA unit ■ Current ESTCP Project ER-0707 Building Building ■ Pressure May not be suitable in very large or Pressure Control very leaky buildings Control ■ Completed “Proof of Concept” study CSIA / CSIA / ■ Additional funding for development Fingerprinting Fingerprinting and validation Multiple methods available to distinguish Multiple methods available to distinguish KEY between vapor intrusion and indoor sources. POINT: between vapor intrusion and indoor sources. 6

SOLUTION: TEST METHODS POTENTIAL METHODS TO DISTINGUISH BETWEEN VAPOR INTRUSION AND INDOOR SOURCES OF VOCS ■ Used successfully by EPA and Hill AFB Real-time Real-time ■ On-site Requires expensive equipment: On-site Analysis Hapsite GC/MS or USEPA TAGA unit Analysis ■ Current ESTCP Project ER-0707 Building Building ■ May not be suitable in very large or Pressure Pressure very leaky buildings Control Control ■ Completed “Proof of Concept” study CSIA / CSIA / ■ Additional funding for development Fingerprinting Fingerprinting and validation Multiple methods available to distinguish Multiple methods available to distinguish KEY between vapor intrusion and indoor sources. POINT: between vapor intrusion and indoor sources. 7

On-Site Analysis: Overview UPSTAIRS ATTACHED GARAGE DOWNSTAIRS BASEMENT Foundation Crack ■ Conduct initial survey of buildings KEY ■ Follow-up in area of highest concentration to POINT: identify source. 8

ON-SITE ANALYSIS: OPTIONS Performance Continuous analysis with USEPA 1 – 5 ppbv quantitation TAGA Unit limits (wow!) TAGA Unit TAGA Unit <1 ppbv detection limit HAPSITE for grab samples Portable Less sensitive in survey GC/MS model (i.e., continuous reading) <1 to 10 ppbv detection Mobile lab limit for grab samples GC/MS Need alternate HAPSITE GC/MS HAPSITE GC/MS instrument for survey 9

SOLUTION: TEST METHODS POTENTIAL METHODS TO DISTINGUISH BETWEEN VAPOR INTRUSION AND INDOOR SOURCES OF VOCS ■ Used successfully by EPA and Hill AFB Real-time Real-time ■ On-site Requires expensive equipment: Hapsite On-site Analysis GC/MS or USEPA TAGA unit Analysis ■ Current ESTCP Project ER-0707 Building Building ■ Pressure May not be suitable in very large or Pressure Control very leaky buildings Control ■ Completed “Proof of Concept” study CSIA / CSIA / ■ Additional funding for development and Fingerprinting Fingerprinting validation Multiple methods available to distinguish Multiple methods available to distinguish Key between vapor intrusion and indoor between vapor intrusion and indoor Point: sources. sources. 10

PRESSURE CONTROL: OVERVIEW Concept: 1) Use controlled NEGATIVE building pressure to MAXIMIZE vapor intrusion. 2) Use controlled POSITIVE building pressure to TURN OFF vapor intrusion. 11

PRESSURE CONTROL: VALIDATION STUDY TESTING PROGRAM Number of Matrix Analyte Location Samples Indoors, 3 locations Indoor air 6 Radon, SF6, VOCs (negative pressure and positive pressure events) Sub-slab, 3 locations Sub slab vapor 6 Radon, SF6,VOCs (negative pressure and positive pressure events) Outdoors, upgradient, once Ambient air 1 Radon, SF6, VOCs at each location Continuous sampling at Differential pressure various sample points Pressure between NA during positive and Gradient indoor/outdoor and negative pressure indoor/sub slab space conditions 12

TIER 3: FIELD PROGRAM 13

TIER 3: FIELD PROGRAM 14

TRAVIS AFB: BUILDING PRESSURE Baseline Negative Positive Pressure Gradient (Pa) Building Foundation Building Envelope 15

TINKER AFB: BUILDING PRESSURE Pressure Gradient (Pa) 16

EFFECT OF BUILDING PRESSURE ON INDOOR RADON CONCENTRATION TRAVIS AFB BUILDING 828 JACKSONVILLE NAS BUILDING 123 Radon Conc. (pCi/L) INDOOR: INDOOR: INDOOR: INDOOR: OUTDOOR OUTDOOR NEGATIVE POSITIVE NEGATIVE POSITIVE PRESSURE PRESSURE PRESSURE PRESSURE Key Point: Control of building pressure resulted in control of radon vapor intrusion. 17

TRAVIS AFB: INDOOR VOC CONC. 18

TRAVIS AFB: INDOOR VOC CONC. Concentration in Outdoor Air 19

SOLUTION: TEST METHODS POTENTIAL METHODS TO DISTINGUISH BETWEEN VAPOR INTRUSION AND INDOOR SOURCES OF VOCS ■ Used successfully by EPA and Hill AFB Real-time Real-time ■ On-site Requires expensive equipment: Hapsite On-site Analysis GC/MS or USEPA TAGA unit Analysis ■ Current ESTCP Project ER-0707 Building Building ■ Pressure May not be suitable in very large or Pressure Control very leaky buildings Control ■ Completed “Proof of Concept” study CSIA / CSIA / ■ Additional funding for development and Fingerprinting Fingerprinting validation Multiple methods available to distinguish Multiple methods available to distinguish Key between vapor intrusion and indoor between vapor intrusion and indoor Point: sources. sources. 20

TECHNOLOGY DESCRIPTION What are Stable Isotopes? e - - e - e - e p p p p p n p n e - - e n n n n Deuterium, Hydrogen, Deuterium, Tritium, Tritium, 2 H, D 1 H 2 H, D 3 3 H, T H, T • Isotopes have the same number of protons – identical atomic number • Isotopes have different number of neutrons – different atomic mass • Stable isotopes do not undergo radioactive decay – tritium is not a stable isotope 21

TECHNOLOGY DESCRIPTION Stable Isotope Fractionation Kinetic Effect Equilibrium Effect Kinetic Effect Equilibrium Effect (reversible) (irreversible) (reversible) (irreversible) H 1 H 1 Biodegradation Biodegradation Cl Cl of PCE of PCE H 2 H 1 12 1 3 C C Cl Cl Evaporation Evaporation Key Differences in isotope ratios between Differences in isotope ratios between samples can indicate different sources. Point: samples can indicate different sources. 22

TECHNOLOGY DESCRIPTION 23

TECHNOLOGY DESCRIPTION Isotope Differences: Indoor vs. Subsurface Sources Manufacturing: Consumer products vs. industrial Manufacturing: Consumer products vs. industrial chemicals. chemicals. Biotransformation: Kinetic isotope effects likely in Biotransformation: Kinetic isotope effects likely in subsurface sources but not indoor sources. subsurface sources but not indoor sources. 24