Green Job Hazards

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Geo-Thermal Energy

Geo-Thermal Energy

The use of geothermal energy is growing rapidly throughout the United States. Geo-Thermal systems use the heat from the earth to create electricity, and to heat and cool buildings. Some geothermal systems pump water underground through piping, allow it to be heated by the earth, and then use the hot water to create electricity or heat/cool buildings. Other systems drill directly into the earth’s natural geothermal reservoirs, using the resulting hot water and steam to create electricity. Some geothermal systems use a brine or saltwater solution while others will use glycol. These solutions may pose hazards of their own to workers.

Hazards and Controls

The hazards associated with this growing industry include some very familiar safety issues that OSHA already has standards on and information about:



  • An employee was installing geothermal piping in a trench that was 6 feet deep and 30 inches wide. The trench was not sloped, shored or braced and it caved in. He was crushed by the dirt and died from asphyxia.

  • At approximately 6:20 p.m. on April 19, 1996, Employee #1, a laborer for Acme Temporary Services, was working at a geothermal power generating facility that was being shut down for periodic cleaning. Workers had been set up in teams of two to open side hatch covers on vessels from which shale and sand were to be removed. Employee #1 was standing to the right of a coworker who was removing the retention bolts from a hatch cover when the hatch popped open and hot water sprayed out over Employee #1. He sustained severe burns on his arms, back, chest, and legs. Coworkers in the area came to his aid, removed his clothing and gloves, and placed him in a full shower. Emergency Services was called and Employee #1 was taken to the office where burn cream was applied. He was transported by paramedics to a local medical facility, and later taken to a regional burn facility. Subsequent investigation revealed that the hot water had been trapped in the vessel due to a faulty drain line.

  • A consultant for a geothermal electric utility was standing at a wellhead near a 2-inch bypass. The gas cap came to the surface and flooded the area with a substantial amount of hydrogen sulfide. The consultant ran and collapsed about 150 feet northwest of the wellhead. He did not lose consciousness, however, and quickly regained his balance. A chemical technician, who was performing daily air monitoring, was also overcome by the hydrogen sulfide release. He donned a self-contained breathing apparatus near the ground, but collapsed before he could turn the air on. He was revived with oxygen. Both workers recovered from their injuries.

  • At approximately 11:35 a.m. on August 23, 1994, Employee #1 entered a 8.4 ft. deep by 8 ft. wide geothermal vault with a 32 in. wide manhole entry to rebuild a pressure reducing valve. Before any chemical substance was introduced into the vault, the oxygen level was between 19.5 and 19.6 percent. Atmospheric testing was conducted by the EC unit and by Employee #1 using a Gastech GX-82 oxygen meter, serial #HX-13452, without an extension hose; the oxygen levels found were between 19.6 and 19.7 percent. After WD-40 and Graff-off were introduced into the vault, the oxygen level dropped to 18.9 percent. Employee #1 also noted hydrogen sulfide levels of 8 ppm. Employee #1 complained of dizziness, nausea, and difficulty in breathing. He was diagnosed as having pulmonary edema, which turned into pneumonia three weeks later. The casual factors of this accident include the employer's failure to provide workers with confined space and hazard communication training and with the material safety sheet for the product used in the confined space. The chemical constituents of WD-40 include aliphatic petroleum distillates and A-70 hydrocarbon propellant; the chemical constituents of Graff-off include isopropyl alcohol and 40 percent toluene by weight.

  • On 7/14/08 at 1030 hrs an employee of Trison Construction Inc. dba Trison Geo-Thermal HVAC was injured. The employer reported the accident 7/17/08 at 1030 hrs. The injured worker was removing a "drill stem" from a 3-inch pipe on a Driltech Marlin M5, Serial # 732658, truck-mounted drilling machine. He wedged a 60-inch pipe wrench near the operator's platform to break the connection. The pipe wrench broke loose, striking the employee on the right knee, fracturing it. This contractor specializes in geothermal drilling.

  • On 05/30/2009 at 5:00 p.m., a worker of Terra-Gen Operating Company, LLC was seriously injured with second- and third-degree burns to his body while at the company's remote worksite near Inyokern, CA, performing his regular assigned duties as an Operation Supervisor at the geothermal electric power generation facility. The worker observed a leak of 150˚-160˚ Fahrenheit geothermal water coming from a temporary diesel engine powered pump and piping system at a collection pond. He shut off the diesel engine of one of the five temporary pumps at the site, then turned around to walk away. After rotating his body he fell into a pool of the heated water. The pressurized water from the leak gouged out an approximately two-foot deep depression in the sand and gravely desert soil. He radioed a coworker and alerted him of the incident. The company's emergency action plan was implemented. The worker was airlifted to Fresno Regional Medical Center to receive treatment. An inspection was initiated by the DOSH Fresno District Office.