acids, they produce deadly toxins that sometimes leak
into the groundwater or into the human food chain.
Some of these toxins remain reactive and hazardous for
up to 100 years before they become nontoxic. When any
of these materials are spilled onto the ground, it must be
considered a major contaminating spill with dangerous
aquifer polluting potential. Some of the larger CESE
used by NCF contain enormous amounts of
petrochemicals. A 25-ton hydraulic crane contains over
214 gallons of potential pollutants, and a twin-engine
scraper contains over 350 gallons. Spillage or dumping
of these amounts of contaminants can be disastrous!
Because of the varied conditions that affect
migration and recovery of a spill, recovery systems must
be tailored for each site. Some of these systems are
covered in NAVFAC DM 5.14, Groundwater Pollution
Small spills that encounter a shallow groundwater
table or that are contained by a natural barrier, such as
rock, stone, or impermeable clay, prevent vertical
migration and can be recovered by using an interceptor
trench, as shown in figure 7-1. This interceptor trench
system is relatively simple and can be built by using
materials and equipment normally available on a
construction site. The trench must bisect the entire width
of the spill to contain it; therefore, the interceptor system
is useful only on spills that can be contained quickly.
The trench depth usually is limited to 6 to 8 feet, because
beyond that depth the ground becomes unstable. An
impermeable barrier, such as rubber sheeting, should be
installed on the downgrade side of the trench. This
barrier prevents migration of the accumulated spill
product and still allows water to pass beneath the barrier.
Since most petroleum products float on water, the spill
can be pumped out into a separator, as shown in figure
7-2. The separated spill can then be disposed of off-site
at an authorized waste-handling facility.
Another method of clearing a spill area is to
completely remove all contaminated soil from the site
to a facility or landfill that is designed to receive such
material. This is called stripping. Stripping must be done
carefully so that the underlying and adjacent soil is not
contaminated by the removal process. Once all of the
contaminants are removed from the site, the excavation
may then be backfilled with dry, clean soil.
The best method, of course, is to be sure that spills
do not occur on jobsites.
As a first class petty officer, you should be aware of
work conditions that cause air pollution and of the
efforts required to minimize or correct the problem.
When incomplete combustion occurs in base
boilers, space heaters, and stoves, the unburned
hydrocarbons and various other fuel components
combine chemically to form by-products. Many of these
by-products are harmful to people and the environment.
The by-products that have the most adverse effect
on the air are carbon monoxide, particulate matter,
sulfur oxides, unburned hydrccarbons, nitrogen oxides,
and lead. The most effective means of controlling air
pollution from incomplete fuel combustion is to
properly and frequently maintain the equipment. In this
way, the equipment is operating at an optimal fuel and
oxygen mixture. Another means of lessening air
pollution, not always under your control, is the use of
only the best grade of fuel. High-grade fuel contains low
particulate matter, low water and sulfur content, and few
Figure 7-1.Interceptor trench with skimmer pump.