This presentation describes a direct way to collect critical off gas emissions-related data and the assess in a manner to help evaluate the need for control measures and impacts to operations while being protective to the public and the work force.

1. 1 © 2009 ARCADISAugust 22, 2015
Trial Excavation Yields Critical
Off-Gas Emissions Data at
Former Manufactured Gas Plant
Donald J. Carpenter, PG
Vice President
ARCADIS, US Inc.
10559 Citation Drive, Suite 100
Brighton, MI, 48116
Phone: 810.225.1970
Email: Donald.Carpenter@arcadis-us.com

2. 2 © 2009 ARCADISAugust 22, 2015
Overview
• Location implications
• Trial excavation
process
• Resulting data
• Conclusions
• Questions

3. 3 © 2009 ARCADISAugust 22, 2015
Project Location has Important
Remedial Implications
• Severe Cold and Heat:
-Record High 115° F
-Record Low -46° F
• Severe thunderstorms and high
winds
• Limited construction season
• High production rates required
Largest Temperature
Extreme on Earth
– The Weather Channel
Largest Temperature
Extreme on Earth
– The Weather Channel

4. 4 © 2009 ARCADISAugust 22, 2015
The MGP Operation is Consistent with the
Thousands of Other MGP Sites Across the Country
• Operated 1888 – 1948,
Demolished in 1950s
• Carburetted Gas Plant
• Land parcel surrounded by
residential, commercial,
and undeveloped properties

5. © 2009 ARCADISAugust 22, 20155
Close
Proximity of
Residents
Emphasizes
Importance of
Understanding
Emissions
200
m
eters
Preliminary off-gas emissions “bounding case” modeling
suggested exceedances of applicable occupational
standards at “reasonable” production rates

6. © 2009 ARCADISAugust 22, 20156
Loading into Highway Trucks
Inventory of
Off-gas
Emission
Sources must
be Accurately
Simulated
Primary
Excavation
Passive Emissions from
Stockpiled Material

7. Imagine the result
A Critical Parameter to be Determined is
the “Release Fraction” of Contaminant
Percentage
released from
given mass at
given
concentration
disturbed in
specific manner
per unit time

8. © 2009 ARCADISAugust 22, 20158
Method
Followed a
Proven
Approach
Backmodeling allows estimate as to the
“Release fraction”

9. © 2009 ARCADISAugust 22, 20159
Accurate
Determination
of Conditions
are Required
• Portable weather station was used
• Wind speed is especially important

10. © 2009 ARCADISAugust 22, 201510
Initial
Excavation
Performed
Until Coal Tar
was
Encountered
• Allowed setup of equipment
• Dress rehearsal
• Another safety review

11. © 2009 ARCADISAugust 22, 201511
Excavation
Paused Upon
Encountering
Coal Tar
• Representative sample collected for
benzene and naphthalene
• Depth of initial excavation was measured

12. © 2009 ARCADISAugust 22, 201512
Multiple
Summa
Canisters
Provide Data
for Entire
Inventory of
Emissions
Multiple Summa Canisters used
• Canisters #1 and #5 – Continuous (50 minute)
• Canister #2 – Active Excavation (10 minute)
• Canister #3 – Passive Emission (30 minute)
• Canister #4 – Secondary Handling (10 minute)

13. © 2009 ARCADISAugust 22, 201513
A Tracer Gas
was used to
Better
Quantify
Emissions
Known mass of “gas duster” was sprayed at a
measured distance during a clocked period of
time (Mass/Unit Time):
• 100% - 1,1 Difluoroethane – unique gas
compound
• Provide “calibration” regarding degree of
dispersion/dilution
• Additional QA/QC check constituent

14. © 2009 ARCADISAugust 22, 201514
Volume of
Excavated
Material was
Determined
• Excavator buckets were counted as back-up
check to volume calculations
• Also provided insight into ground stability
and difficulty in digging

15. © 2009 ARCADISAugust 22, 201515
Trial
Excavations
Performed both high- and moderate-
concentration areas
AC1
TP3
Moderately impacted
Highly impacted

16. © 2009 ARCADISAugust 22, 201516
AC1 Benzene
Emissions
Well below occupational standards
- About 20% of OSHA TWA 8-Hour PEL
AC1 AREA - BENZENE (ug/M3
)
8-Hour
TWA PEL
Sample

17. © 2009 ARCADISAugust 22, 201517
TP3 Benzene
Emissions
Exceeded Short Term Exposure Level (STEL)
- Concentrations were several times higher than 8-Hour
TWA PEL
- Emissions were about 22 times higher (adjusted) than
AC1 area
EST.
TP3 AREA - Benzene (ug/M3
)
STEL
8-HOUR
TWA PEL

18. © 2009 ARCADISAugust 22, 201518
TP3
Naphthalene
Emissions
Exceed nuisance odor concentrations
- Detected transitory odors hundreds of feet away
- Estimated passive emissions did not significantly
decrease over time
- May have implications for sizing of stockpile TP3 AREA –
NAPHTHALENE
(ug/M3
)
EST.
NUISANCE
ODOR LEVEL

19. Imagine the result
Emission Rate can be Determined
by Two Independent Means
1) Estimate based on Off-Gas Concentration compared to Tracer Gas
Concentration
2) Backmodeling using Air Dispersion model and Atmospheric
Conditions (wind speed)
Both Methods report the following release fractions:
Benzene
• Primary Excavation – 8.5%
• Passive Emission – 17.4%
• Secondary Emissions – 9.8%
• Total Emissions – 32% (of “original”)
Reasonable, but not exceptionally high release fractions (40% to
70%) have been reported.

20. © 2009 ARCADISAugust 22, 201520
580 ug/M3
:
Scenarios for Both “Worst-
Case” and “Base Case”
Demonstrate Protectiveness
to Community
• “Worst case” scenario
• High emission waste
• Worst case
atmospheric conditions
• Point source emissions
• “Base Case” adjusted
for wind direction,
longer exposure
duration, and actual
duration of operation
4.5 ug/M3

21. © 2009 ARCADISAugust 22, 201521
Naphthalene
Odor Footprint
is Limited to
the Site
Nuisance odor threshold met at less than 100
meters
ODOR THRESHOLD

22. © 2009 ARCADISAugust 22, 201522
Confining
Structure
Evaluation
Modeling demonstrates that confining structure
and associated ATS are unnecessary
-18,000 acfm Air Treatment System (ATS) would be
required
-Would provide about a 44% improvement in
emissions
-Similar degree of improvement can be achieved by
comprehensive application of foam

23. © 2009 ARCADISAugust 22, 201523
Conclusions • Quantification of off-gas emissions is critical
to effective project safety
• Critical determination: “Release fraction” of
contaminant
• Trial excavation followed a proven approach
• Multiple canisters provide data for entire
inventory of emissions
• Modeling demonstrates short- and long-term
protectiveness
• Nuisance odors would be largely confined to
the Site
• Modeling determined confining structure and
associated ATS are unnecessary

24. Imagine the result
Imagine the result