Understanding Building Materials Contribution to Indoor Air Quality

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1 Understanding Building Materials Contribution to Indoor Air Quality Catherine E. Regan, P.E. ERM Boston, MA R. Joseph Fiacco, P.G. ERM Boston, MA 27 th Annual AEHS International Conference March 2017 Copyright 2017 by ERM Worldwide Group Limited and/or its affiliates ( ERM ). All Rights Reserved. No part of this work may be reproduced or transmitted in any form or by any means, without prior written permission of ERM.

2 Why do we want to know? EPA OSWER Guidance - June 2015 Increased emphasis on VI pathway sampling Focus on multiple lines of evidence Emphasis that OSHA is not applicable in commercial settings if: Chemical is not or is no longer present Can we evaluate the VI pathway in a facility following chemical usage changes or facility shutdown? 2

3 What do we do? OSHA TCE PEL = 537,000 µg/m 3 EPA TCE RSL = 3 µg/m 3 ACGIH TCE TLV = 54,000 µg/m 3 TCE 3

4 What do we do? How will former chemical use affect the VI pathway evaluation? PCE 4

5 Project Example Further VI evaluation required Known TCE concentrations in sub-slab soil gas and indoor air Building sale imminent Dynamic 4-day 5 characterization

6 Preliminary Conceptual Site Model TCE in Indoor Air Vapor intrusion through concrete Back Diffusion of TCE From the Concrete Slab Bolt Hole / Crack TCE Diffusion Concrete Floor Slab TCE in Sub-Slab Soil Gas Soil 6

7 Data Collection Approach Summary TCE in Indoor Air Static Flux Chambers Concrete Cores Back Diffusion of TCE From the Concrete Slab TCE Migration Pathway Bolt Hole / Crack TCE Diffusion Concrete Floor Slab TCE in Sub-Slab Soil Gas Soil 7

8 Data Collection Approach Summary TCE in Indoor Air Static Flux Chambers Concrete Cores Controlled Pressure Testing Method Considered but not used due to property owner s request Back Diffusion of TCE From the Concrete Slab TCE Migration Pathway Bolt Hole / Crack TCE Diffusion Concrete Floor Slab TCE in Sub-Slab Soil Gas Soil 8

9 Indoor Air Sampling with Hapsite Indoor Air sampling collected via syringe and tedlar bag Analyzed with the Hapsite for TCE Provided an area of focus - increased indoor air concentrations 9

10 Results Indoor Air 10

11 Results Indoor Air Indoor Air Concentration µg/m 3 : >100 >30 >2 11

12 Static Flux Chambers Set chambers in areas of known/likely TCE use Equilibration >8 hours Collected sample via syringe and tedlar bag Analyzed tedlar bag for TCE via Hapsite 12

13 Results Static Flux Chambers 13 Static Chambers µg/m 3 > 10,000 1,000 10, , < 100

14 Concrete Core Sampling Used Hapsite data from flux chamber sampling to choose locations to collect concrete cores Cores sampled at three intervals to evaluate concentrations gradients (0, 2.5 and 5 ) Concrete cores analyzed for TCE by stationary laboratory after field activities completed 14

15 Results Concrete Cores Core in in in Core in in in Core in in (U) 6.0 in Core in in in Core in in in

16 Sub-Slab Sampling Sub-slab samples collected via lung box/tedlar bag and analyzed via Hapsite Locations added as concentrations were measured to delineate sub-slab soil gas 16

17 VI Pathway Sampling Bolt holes and cracks in the concrete Sampled with lung box/tedlar bag or direct with HAPSITE intake wand Evaluated whether bolt holes and cracks connected to subsurface 17

18 Results Sub-Slab Soil Gas and VI Pathways TCE Concentration (pathways and subslab) µg/m 3 : >10,000 1,000-10, , <100 Steel plate over concrete 18

19 Vapor Intrusion Investigation Results Historical Building Use Sub-Slab Soil Gas and Preferential Pathways Legend: IA=Indoor Air SS=Sub-slab SC=Static Chamber TCE Concentration (pathways, SCs, and sub-slab) µg/m 3 : >10,000 1,000-10, , <100 Static Flux Chambers Indoor Air Indoor Air Concentration µg/m 3 : >100 >30 >2 19

20 What did we find out? Focused in on specific building area Flux chambers and concrete profiles indicated contribution to indoor air from concrete off-gassing Likely attributable to point source use and spills Off-gassing still occurring over 1 year after facility shut-down but. Sub-slab soil gas had more consistent and much higher concentrations than what appeared to be present in concrete Significant cracks and breaks in the concrete were found to have good communication with the indoor air, collocated with high sub-slab soil gas concentrations. 20

21 Vapor Mitigation SSD System SSD System Start Up Target = 2 µg/m3 21

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