GEO Inc. is proud to have over 25 years of work without any OSHA reportable incidents. All field personnel have 40 hour certifications, US Army Corp Engineer Certificates and RSO Refinery Safety Certification. Our organization submits to PICS auditing.
Prior to site mobilization, GEO Inc. develops a detailed Site-Specific Health and Safety Plan (HASP) to address potential health and safety hazards and control measures throughout the various work tasks. Safety controls and precautions can be separated into three categories: (1) the gas distribution system, (2) the individual burner controls, and (3) the emissions controls.
The gas distribution system (GDS) is defined as the fuel source, piping, valves, and pressure regulators that are involved in supplying fuel (either natural gas or propane) to the control systems of the individual GTR™ burners. Upon completion of the well-field design, the placement and number of TCH wells are known and the GDS can be sized accordingly.
The GDS piping can be installed in the subsurface from the fuel source to the TTZ via trenching or conduit methods. The GDS piping is installed aboveground on stands to isolate it from the heat. Prior to selection of the specific components, all local codes and regulations are reviewed by a certified professional. Locally regulated and required inspections are performed prior to startup.
The pressure regulators are the most critical components of the GDS and as such, specific precautions are taken to ensure their functionality. Dual redundant pressure regulators are placed to safeguard and control the necessary operating pressure of gas delivered to the control systems of the individual GTR™ burners. Maintenance schedules are closely adhered to and documented, and all pressure regulators are closely evaluated for proper function before installation, during operation, and after decommissioning.
During startup/system optimization, the air to fuel equivalence ratio (λ) is adjusted to maximize the efficiency of each individual GTR™ burner. When the GTR™ burner is operating ideally, all the fuel is being converted to carbon dioxide (CO2) (Equation 1) and fuel efficiencies of 65 - 80% are achieved. If λ begins to operate outside of its ideal ratio, the efficiency will decrease and incomplete combustion will occur resulting in carbon monoxide (CO) emissions (Equation 2). The same products are observed for complete and incomplete combustion of propane.
To prevent incomplete combustion and maximize fuel efficiency, the emission stream is monitored for CO. If CO is detected, the telemetry system will alert the project manager so that the burners can be inspected and adjusted. If CO levels exceed the pre-set limit, the affected GTR™ burner(s) will automatically shut down via the PLC transmitting an "off" signal to the gas valve.
In addition to CO, the presence of combustible vapors is also monitored in the emission stream. The lower explosion limit (LEL) is the leanest concentration of a given gas at which a flame can be sustained if provided an ignition source. If the concentration of combustible gases reaches 30% of the LEL, the fuel source will be automatically turned off.
The GTR™ burners operate individually, which allows for a staggered approach to heating the well-field when the extent of contamination is not homogeneous. The controls to each burner are located inside the GTR™ burner housing and the valves to optimize λ are located on the GTR™ burner body. The fuel mixture is ignited by an ignition electrode.
The controls associated with each burner have been designed with safety in mind. All electric components are certified by one or several Nationally Recognized Testing Laboratories (NRTLs) and all installations are performed by qualified technicians.
Upon startup of the GTR™ burner, there is a 10 second timer that allows for venting of the burner body prior to the ignition cycle. After 10 seconds, the GTR™ burner controls are enabled and a pressure switch checks for airflow through the burner; if there is insufficient flow through the burner, a warning light will illuminate and the startup sequence will cease. If there is sufficient flow through the GTR™ burner, the burner gas valve will open and both the automatic electric ignition device and the automatic flame monitoring system will initiate simultaneously.
The automatic electric ignition charges the ignition electrode to ignite the air-fuel mixture and the automatic flame monitoring system senses a flame through the ionization electrode. If at any time the ionization electrode does not detect a flame, the burner gas valve will close and a warning light will illuminate. The ionization flame detector circuit is isolated from the ionization electrode by an isolation transformer.
Fugitive emissions are defined as the release of hazardous air pollutants to the atmosphere; the driving force of these emissions is usually pressure. When the ground is heated, soil vapor expands creating a slight pressure and hence a driving force for fugitive emissions.
Fugitive emissions are mitigated by installation of an impermeable cement thermal cover over the surface of the target treatment zone (if one is not already present) and operating an SVE system to create a slight vacuum to the well-field. One or several pressure transducers placed within the TTZ are used to monitor the vacuum being applied to the well-field and will shut down the system if insufficient vacuum is detected. As a mitigation control measure, SVE systems are oversized to allow for much more vapor flow and vacuum than is specified in the designed.
| Summary Table of Safety Controls | |
|---|---|
| Gas Distribution System | |
| Inspection performed by local certified professional prior to operation | Guarantees compliance of all local codes and regulations and increases safety |
| Dual redundant pressure regulators | Provides one fail-safe/ back-up regulator |
| Maintenance and inspection of pressure regulators performed regularly | Increases reliability and identifies potential problems |
| Monitoring of CO and LEL in emission stream | Identifies incomplete combustion of fuel |
| Burner Controls | |
| Electrical Certification | Guarantees electrical compliance |
| Pre-venting prior to ignition cycle | Purges the burner housing with clean air prior to ignition cycle |
| Pressure differential switch inside burner housing | Ensures air flow before ignition cycle |
| Electronic combustion monitoring | Prevents gas flow when flame is not present |
| Isolation transformer on ionization flame detector circuit | Isolates power at the ionization flame detector circuit from the ionization electrode |
| Fugitive Emissions Control | |
| Impermeable layer over surface of site | Prevents fugitive gases and heat loss to the atmosphere |
| Use of SVE to apply slight vacuum to well field | Recovers gases from subsurface |
"GEO's Equipment is Superb. We ran a 3 month pilot test and extracted over 2,300 gallons of pure 1,2,-DCA and other chlorinated hydrocarbons (24,000 pounds of contaminant mass) with very little down time even under extreme weather conditions (heat)."
-- Craig Snider PG, Environmental Management
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