Elevated Subsurface Temperatures CO2 Injection: $21,000 Follow-Up Monitoring: $4,000 Subtotal: $48,000 Equipment Allocation: 5.0 % ($2,400) Contingency: 10 % ($4,800) Total Cost: $56,000

Elevated Subsurface TemperaturesUse of Technology to Identify and Mitigate Areas of Concern

Presentation Outline

Presentation Outline

• Subsurface Oxidation Events

� The Basics

• Case Study

� Thermal Imaging Basics

� Identify Additional Areas

� Confirm the Extent

� Mitigate the Issue

� Confirm Effectiveness

• Regulatory Concerns

• Cost

• Closing

• Questions

Subsurface Oxidation Events

The Basics

Subsurface Oxidation EventsThe Basics

• Not the same thing as an Elevated Temperature Landfill

(ETLs)

� ETLs typically have an exothermic chemical reaction occurring over a

large area

� ETLs are normally very deep with initial reaction occurring at depth

� ETLs associated with specific waste streams that the landfill accepted

• Subsurface Oxidation Events

� Typically occur in shallow areas

� Typically can be identified by Carbon Monoxide production

Subsurface Oxidation EventsThe Basics

• Defining Elevated Subsurface Temperature

� 100°F to 120°F

– Expected Temperature Range

� 120°F to 131°F

– Somewhat warm but within

regulatory constraints

� 131°F to 145°F

– Elevated but typically allowable as

Alternative

– Additional monitoring typical

� < 145°F

– Concerning

– Trigger for EST 4 letter word starting with “F” FIRE

Case Study

Testing the Approach

Case StudyInitial Request

• Site contacted Tetra Tech that an area recently excavated

was exhibiting signs of Elevated Subsurface Temperature

� Smell of burning

� Slight smoking

� Area has historically had similar incidents in the last 2-3 years

• Tetra Tech was asked to:

� Identify any additional Areas of Concern

� Define the extent of the Areas of Concern

� Mitigate the Elevated Subsurface Temperature Areas of Concern

� Confirm effectiveness through follow up monitoring

Case StudyThermal Imaging Basics

• Some basics about thermal imaging

� It is not as expensive as it once was in the past

� If aerial thermal imaging is used it must be verified with ground-based follow up

� Uses variances in surface temperatures to provide visual differences

� Can be skewed by surface fluctuations (grass versus dirt, for example)

� The temperature scale is displayed based on the view of the camer

Case StudyThermal Imaging Basics

Variances between the temperatures in the pictures are

used for the colors in the image

Case StudyIdentify Additional Areas


Original Area of Concern

Thermal Signature #1

Below Grade Header Line

Excavator Location







Case StudyConfirm the Extent





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• Temporary Monitoring Probes were installed using an

excavator

6 – 8’

1’

1” Diameter Black Iron Pipe (10’ Long)

1” Diameter Threaded Cap

1” Diameter Threaded Cap

1/4” Perforations


• Temporary Monitoring Probes had the following performed

prior to mitigation activities for confirmation of Elevated

Subsurface Temperatures:

� Methane

� Carbon Dioxide

� Oxygen

� Balance

� Temperature

� Carbon Monoxide






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Case StudyMitigating the Issue

• After confirming the two (2) Areas of Concern, mitigation

strategies were analyzed

• A multi-faceted approach was selected:

• Application of additional

soil to surface

• Wetting of the surface

• Compaction of the soil

surface

• Injection of liquid

carbon dioxide

Case StudyMitigating the Issue

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3 4

5

Case Study Mitigating the Issue

• Liquid CO2 Fun Facts

� Delivery typically occurs between –60°F to 0°F and a pressure of 100

to 600 PSI

� Serious health hazard for inhalation, cryogenic injury and severe

frostbite

� Approximately 8.5 ft3 of gas is created for each pound of liquid CO2

� Sudden change in temperature or pressure will cause dry ice snow to

form

� Rapid discharge of liquid CO2 through a line will cause a build-up of

static electricity

Liquid CO2 Injection is dangerous!!!


Soil Placement and Compaction


Liquid CO2 Injection Well Installation


Liquid CO2 Injection Well Construction


Liquid CO2 Injection Well Construction


Liquid CO2 Injection







Case Study Confirm Effectiveness

• Additional monitoring after the injection of liquid CO2 was performed to confirm the effectiveness of the mitigation measures

• Monitoring included:

� Methane

� Carbon Dioxide

� Oxygen

� Balance

� Temperature

� Carbon Monoxide

• Monitoring was performed regularly for a period of one month

Case Study Confirm Effectiveness

• Gas monitoring indicated Carbon Dioxide concentrations

greater than 94% by volume in some nearby Temporary

Monitoring Points

• Carbon Monoxide concentrations were found to decrease

over 60% within 24 hours of the injection

• Temperatures reduced over 16% over a 20 day period

• Continued monitoring has not indicated any evidence of the

elevated subsurface temperature event

Regulatory Concern

Informing the Agencies

Regulatory ConcernInforming the Agencies

• Notification was provided to the regulator in this event

• There was no exceedance of regulatory limits that caused

the event

• Go through specifically the regulatory requirements

associated with the incident that is being addressed:

� Is the regulator already aware of the issue?

� Is the issue being addressed because of a regulatory issue?

� Will the regulator be required to be notified?

� Is there anything in site permit that calls out the activities?

Cost

The Bottom Line

CostThe Bottom Line

• Initial thermal Investigation:

� Drone Pilot $175/hr for 8 hours

� Drone Spotter $155/hr for 8 hours

� Video Processing $125/hr for 4 hours

� Drone $100/hr for 8 hours$4,000

CostThe Bottom Line

• Monitoring Well Installation and Monitoring:

� Construction Crew $2500/day for 1 day

� Monitoring Technician $110/hr for 8 hours

� Materials $450/well for 8 wells $7,000

CostThe Bottom Line

• Liquid CO2 Injection Wells Installation:

� Construction Crew $2500/day for 1 day

� Supervisor $175/hr for 8 hours

� Materials $1,500/well for 5 wells$12,000

CostThe Bottom Line

• Liquid CO2 Injection:

� Supervisor $175/hr for 16 hours

� Technician $110/hr for 16 hours

� Liquid CO2 $8,000/tanker for 2 tankers (20 tons each)

$21,000

CostThe Bottom Line

• Follow-Up Monitoring:

� Monitoring Technician $110/hr for 24 hours (over 1 month)

� Office Staff $120/hr for 10 hours

$4,000

CostThe Bottom Line

Initial Thermal Investigation: $4,000

Monitoring Well Installation and Monitoring: $7,000

Liquid CO2 Injection Well Installation: $12,000

Liquid CO2 Injection: $21,000

Follow-Up Monitoring: $4,000

Subtotal: $48,000

Equipment Allocation: 5.0 % ($2,400)

Contingency: 10 % ($4,800)

Total Cost:Total Cost:Total Cost:Total Cost: $56,000$56,000$56,000$56,000

Cost Per Acre:Cost Per Acre:Cost Per Acre:Cost Per Acre: $46,000$46,000$46,000$46,000

Compare to the on-going monitoring and mitigation activities associated with the

traditional approach

Closing

Summary

Closing Summary

• Thermal imaging has the potential to identify areas of elevated subsurface temperatures

� Limited to shallow areas

� Requires experience to interpret results

• Liquid CO2 Injection was successful in mitigating the subsurface elevated temperature areas at this particular landfill

� Can be dangerous

� Needs to be designed and operated properly

� Has multiple benefits for this application

• More testing is required to fully evaluate the processes effectiveness but preliminary results were exceptional

Thank you

Questions

Lee Daigle – [email protected]

Documents

Elevated Subsurface Temperatures CO2 Injection: $21,000 Follow-Up Monitoring: $4,000 Subtotal: $48,000 Equipment Allocation: 5.0 % ($2,400) Contingency: 10 % ($4,800) Total Cost: $56,000