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Waste Disposal Methods 205

however, are prohibited within three miles of shore in the United
States, and the discharge of oil-based drilling mud wastes are pro-
hibited in all United States waters. Where offshore discharges are
prohibited, waste solids must be transported to shore for disposal
(Arnhus and Slora, 1991). This is generally more expensive than
offshore treating and discharge.

Onshore Discharges

Many solid wastes, particularly drill cuttings and produced solids,
can be discharged by spreading them over the land surface. If the
solids have been treated and are not contaminated with hydrocarbons,
salt, or heavy metals, then obtaining permits for surface disposal may
be relatively simple.
The suitability of a solid waste for surface discharge can be assessed
through its electrical conductivity (EC), sodium adsorption ratio
(SAR), the exchangeable sodium percentage (ESP), and the oil and
grease (O&G) levels. Maximum • values generally recommended
for these parameters are: EC < 4 mmhos/cm, SAR < 12, ESP < 15%,
and O&G < 1% (Deuel, 1990). These parameters are discussed in
more detail in Chapter 3. Another measure of the suitability of a solid
waste for surface discharge is its heavy metal content. Maximum
recommended accumulations of heavy metals in soil are presented in
Table 7–1.
Treated waste solids can be used for road and site construction.
Construction grade gravel and sand can be used as fill material on
roads and drilling pads. Such use of treated solids minimizes the need
for quarried gravel, which further lowers the environmental impact of
drilling and production activities (Schumacher et al., 1990).
Land treatment can be used for the disposal of solids containing
only hydrocarbons, particularly if the treatment is designed to degrade
the hydrocarbons by biological processes (Bleckmann et al., 1989;
Biederbeck, 1990). There are two major forms of land treatment in
use: landspreading and landfarming. Landspreading is when wastes
are spread over the surface of the ground and then tilled into the soil.
After this initial tilling, no further action is usually taken. Landfarrning
is an enhanced version of landspreading in which additional processing
of the soil is conducted after the initial tilling. In landfarming, the soil
is commonly processed for several years after the initial application