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Transmission Public Health and Safety

Public Health and Safety
Present, Potentially Affected

Transmission lines must meet certain state and federal safety code requirements, including the National Electric Safety Code. Health and safety plans accompany transmission line sites to decrease the risk of malpractice. These plans strive to educate and train employees on evacuation drills, how to operate heavy equipment, electrical and wildfire procedures, personal protective equipment, and mitigating electromotive force (EMF) impacts. Acquiring these skills will help employees, site visitors, and landowners stay safe.

Public Health and Safety Impacts & Mitigation

Public health and safety impacts range from minor to severe, especially if mitigation measures and response teams are not in place. Activities such as herbicide and pesticide application, dumping, blasting and chemical use require specialized training to decrease personal and off-site injuries. Other impacts such as the Corona effect and mitigating construction traffic require planning and maintenance care to decrease safety impacts.

The Corona effect, or ‘critical disruptive voltage’ occurs when the power threshold exceeds its maximum voltage capacity, the field strength increases and the air surrounding it becomes stressed. The ions separate and cause atmospheric conducting. This results in the line producing a purple or blue luminescent glow, ozone gas discharge, and a buzzing sound. These discharges naturally occur in high-voltage systems if the electric field strength is not limited or the power lines are not equip for the air’s moisture levels.

Typical mitigation measures include the following:

Traffic

  • Indicate heavy equipment or oversized loads with pilot cars, traffic control barriers, and warning signs. Schedule these loads around peak traffic periods to reduce regular traffic congestion and delays.
  • Encourage employee carpooling to decrease cars at the construction site.

Construction

  • Construct circuit breakers to sense a line-ground fault from an energized phase conductor and quickly de-energize the line. Grounding mitigates fire hazard from high voltage transmission lines. Objects that increase induced current may include, fences, metal buildings, and pipelines.
  • Clear vegetation and install spark shields on the construction site instead of using water.
  • Post speed limit signs on access roads and in construction zones to mitigate personal injuries and equipment damage.
  • Mark guy wires with safety reflectors, high-visibility tape or plastic, or a similar material to make them highly visible to the public.

Herbicides and pesticides

  • Follow manufacturers instructions for mixing and use minimum application.
  • Equip vehicles transporting chemicals with Hazardous Materials Spill Management Kits.
  • Only apply herbicides and pesticides to specified areas and species.
  • Avoid areas frequently visited by humans and domestic animals and their food sources (i.e., yards, pens, food crops, drinking water, feed storage areas).
  • Avoid spraying, dumping excess pesticides, or scattering contaminated vegetation near water sources or in runoff pathways. If soil or groundwater contamination occurs, notify corresponding agencies.
  • Evaluate soil characteristics prior to application to determine the soil’s permeability.
  • Avoid pesticides and herbicides in areas with sandy soils near sensitive areas, and in areas with high soil mobility.
  • Use pesticides with 3 months or less half-lives and maximize the effectiveness with the largest droplets or pellets.

Corona Effect

  • To mitigate critical breakdown voltage interferences, increase conductor diameters and keep them dirt and debris free.
  • Use hardware that reduces audible noise, and radio and TV interference. To avoid sparking, maintain tension on all insulator assemblies. This assures positive contact between insulators.
  • Avoid scratching or nicking the conductor surface, which trigger corona effects.
  • Keep dirt and debris off of the conductor.
  • Frequently patrol the transmission line corridor to repair or replace damaged insulators or other line materials that could cause interference.

Dumping

  • Store and dump hazardous waste at off-site facilities.

Personal Protective Equipment

  • This includes safety glasses, hard hats, gloves, durable pants, and long sleeve shirts. To reduce falling injuries, use safety nets, a personal arrest system or guardrails when six feet or more above the ground.

Waste disposal

  • Trash and human waste burial is not permitted. Contain trash on site and haul it to an approved landfill. Avoid treating human waste from portable toilets on site.

Helicopters

  • Coordinate with local farmers to reduce crop dusting interruptions and design a flight path that avoids schools or densely populated areas.
  • Fuel and house helicopters at local airfields or at staging areas.

Blasting

  • Develop a Blasting Plan to identify safety, use, vibration limits, storage, blasting sites, and transportation requirements to instill public safety.
  • To ensure employee and patron safety during blasting activities, mark off the area with flags, barricades, and warning signals. Use blast mats to prevent damage and injury from fly rock.
  • Coordinate with pipeline operators if blasting occurs nearby to follow appropriate procedures.
  • Compensate landowners for any blasting damage or repair the area.

Fire

  • Equip construction, operation and maintenance vehicles with fire suppression gear such as shovels, buckets, and fire extinguishers to decrease response time.
  • Fuel all highway-authorized vehicles off-site to minimize fire risks. To minimize the risk of fire, fuel all highway-authorized vehicles off-site.

Hazardous Materials

  • Store hazardous materials in proper containers (or secondary containers) with updated labels. Remove any excess material when the project concludes.