Page 138 - 6201

behind radioactive waste that can settle inside pipes, sludge, equipment, evaporation ponds,
waste water, and drilling mud.
During drilling, a mixture of oil, gas, and underground formation water is pumped to
the surface. When the water is separated from the oil and gas, it is called produced water.
Produced water can contain salt, oil, grease, chemicals used in drilling, and naturally
occurring radioactive material. It is the largest volume waste from oil and gas production.
Produced water in the past was disposed of in evaporation ponds, but is now generally
reinjected into deep wells or discharged into non-potable coastal waters. An estimated 35
percent of produced water requires disposal because it cannot be recycled. Past disposal
practices and accidental releases of produced water could contaminate groundwater.
Health and safety concerns at oil and gas fields include possible exposure to hydrogen
sulfide, a poisonous and flammable gas that occurs naturally in oil and gas. It is an extreme
health hazard because it can be fatal or harmful if inhaled. Hydrogen sulfide occurs in many
areas marked with warning signs, but can be present in unidentified spaces.

126