passive & active soil vapour sampling - a complementary ......passive & active soil vapour...

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Passive & Active

Soil Vapour Sampling -

A Complementary Approach

James Blackwell1, John Massie2 & Matt Collyer2

14Sight Consulting, Level 6, Aviation House

12-22 Johnston Street, Wellington, 6011, NEW ZEALAND 2Edge Group, Level 1, 423 City Road, South Melbourne, VIC 3205,

AUSTRALIA

[email protected]

mailto:[email protected]


Preamble • This is a case study of works conducted at a previous role for a consultancy in Australia

(Edge Group).

• The use of the sampling technologies detailed in this presentation is not an endorsement or

‘sales pitch’. There are a number of similar proprietary products on the market, that have

different site-specific applications.

• Soil vapour issues are often forgotten about in the broader context of contaminated land

assessment. Growing issue over past 5-10 years around the world in recognising risks posed

by soil vapour.

• Soil vapour is a contaminant in soil, albeit in a different phase, occupying pore space.

Ministry for the Environment ‘National Environment Standard for Assessing and Managing Contaminants in Soil to Protect Human Health (2011)


The Site • Large, active manufacturing facility (5

ha). Limited access, busy Site, operates

24/7, many buildings and high traffic.

• Metal product manufacture since 1950.

• Key contaminants = PCE and TCE

chlorinated solvents used up to 1990’s

for both liquid PCE (pit) and vapour TCE

(enclosure) degreasing.

• Petroleum hydrocarbons also

contaminants of concern from general

manufacturing processes and

machinery.

Potential Source Areas - Edge Group Pty Ltd 2015

Image from Associated Press Image from www.michigan.gov

http://www.michigan.gov/


The Approach • Need to quickly assess potential on-

site human health risks associated

with potential contamination.

• Therefore a staged, complimentary

approach was adopted:

o Initial, low impact, hi-resolution

Preliminary Passive SV assessment

(PPSVA) using WMS-LU samplers.

oSubsequent, conventional, targeted

active SV Monitoring Events

(SVMEs) using active SV sampling

(vacuum canisters). PPSVA and SVME Sample Locations - Edge Group Pty Ltd 2016


PPSVA Results • Results identified 24 locations with

criteria exceedances.

• Excellent correlation between suspected

source areas and results.

• 7 source areas – including 2 previously

unknown.

• Maximum reported concentrations:

o PCE:150,000 µg/m3

o TCE: 180,000 µg/m3

o DCE: 198,000 µg/m3

o VC: 24,000 µg/m3

o TRH F1: 11,000,000 (TRH) µg/m3 TCE Concentrations in Soil Gas – PPSVA - Edge Group Pty Ltd and SiREM 2015 WMS-LU Sampler - Edge Group Pty Ltd, 2015


SVME Results • Results identified 26 locations with criteria

exceedances (24 in PPSVA).

• Results from 4 SVMEs (Aug-15, Nov-15,

Mar-16 and September-16) showed good

correlation and repeatability.

• Narrowed down to 6 source areas –

Previous apparent TRH impact area

actually due to interference from wider

area of CHC impact.

• Maximum reported concentrations:

o PCE: 960,000 µg/m3

o TCE: 2,300,000 µg/m3

o DCE: 340,000 µg/m3

o VC: 260 µg/m3

o TRH F1: 610,000 (TRH) µg/m3

TCE Concentrations in Soil Gas – SVME 3 - Edge Group Pty Ltd and SiREM 2016

Active SV Sampling from SVP Edge Group Pty Ltd, 2015


PPSVA and SVME Data • Significant variation between individual results and poor direct

correlation (R2 scatters):

o SVME total CHCs generally > PPSVA total CHCs.

o PPSVA results contained more 1,1-DCE/VC (‘lighter’).

o SVME results contained more PCE/TCE (‘heavier’).

• However, good overall spatial and contaminant type

correlation - Impacts confirmed in 55% of duplicates.

• Clear identification of 6 key SV source areas:

o 4 known historical sources/activities ( ).

o 2 previously unknown areas ( ).

• Variability between results likely due to:

o Not conducted at same time (variations between SVMEs too).

o PPSVA samples collected at 1.0 m vs SVME mostly sub-slab.

o WMS-LU has greater affinity for the ‘lighter’ more mobile CHCs.

o Long term deployment for PPSVA vs ‘grab’ sample for SVME

may have led to a degree of starvation and underreporting of

‘heavier’ CHCs in tight clay formation.

Key Soil Vapour Impact Areas and Sources - Edge Group Pty Ltd 2016

TCE Degreaser

Previously Unknown

(surface discharge) Metal Presses

PCE Degreaser

Chemical

Storage

Previously Unknown

(impacted fill and UST)


Relative Concentrations - CHCs

PPSVA SVME 3


Indoor Air Assessment • IAQ and SVME 2 conducted at same time – direct

comparison.

• Combined passive personal and active static sampling methods used:

o Passive: Parallel use of Radiello TDT (RAD 145) and CS2

(RAD 130) types to have detection range from low

(environmental) to high (workplace) concentrations - 16

worn by Site workers across Site;

o Active: Use of 6 L vacuum cans - 18 fixed locations across

Site;

o All samplers deployed over 8-hr period, for each of 3 shifts.

o Outdoor ambient air background ‘control’ samples also

collected.

o Assessed against both environmental and Safe Work

Australia 8-hr TWA criteria.

Analysis of Indoor Air and Soil Vapour Samples - Images from Envirolab 2016

Radiello sampler and badge kit - Image from www.sigmaaldrich.com

Low and standard uptake rate Radiello diffusive bodies - Images from www.sigmaaldrich.com

http://www.sigmaaldrich.com/

http://www.sigmaaldrich.com/


Indoor Air Assessment • IAQ and SVME 2 conducted under ‘worst case’

conditions with high temp, decreasing pressure

and low rainfall (Lucky!).

• Results identified no exceedances of applicable

criteria for CHCs in indoor air, but known Site

chemicals were detected.

• Thought likely a result of building type, ventilation

and thick slabs.

Analysis of Indoor Air and Soil Vapour Samples - Images from Envirolab 2016


Outcomes & Conclusions • Rapid identification of significant SV

impacts at the Site in the PPSVA using WMS-LU at comparatively low cost.

• Quantitative results of PPSVA can be compared to criteria to allow initial assessment of potential risks.

• Allowed active SV assessment to target of key SV impact areas focus on delineation.

• Clear identification of SV impact/source areas, improved our early understanding of the CSM.

• Early identification of potential SV risks allowed prompt IAQ assessment of potential risks to Site users.

CSM Cross Section - Edge Group Pty Ltd 2016

CHCs IN GROUNDWATER


Outcomes & Conclusions • Development of new visualisation tools

for WMS-LU and collaboration with

SiREM and University of Waterloo.

• Refinement of approaches with

laboratory for data optimisation.

• Ascertained that while no apparent risk

to indoor air / Site workers; significant

sources of SV remain at the Site that will

require remediation.

• SV was not found to be accumulating in

sub-surface utility trenches / conduits –

does not eliminate them as a pathway

though.

CSM Cross Section - Edge Group Pty Ltd 2016

CHCs IN GROUNDWATER


Thanks

Any Questions?

Consultants – Australia and Canada

Laboratories – Australia Drillers – Australia

James Blackwell

Senior Land & Water Quality

Consultant

4Sight Consulting Limited

E: [email protected]

mailto:[email protected]

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