TM 5-852-5/AFR 88-19, Volume 5
The pipe must be of sufficient height so that the ice
accumulates at high rates in septic tanks in low
mound does not plug the outlet. A dual outlet con-
temperature soils. Annual sludge removal is required
structed as a wye with a valve on each branch has
to avoid clogging problems in the adsorption field.
been successfully used to overcome this problem.
Design procedures are similar to conventional
When the ice mound approaches one outlet, dis-
practice for these systems. Insulation of the septic
charge is shifted to the other leg for the remainder
tank is desirable; a 2-inch thickness of rigid
of the winter. Figure 9-3 illustrates design details for
polystyrene board will retain heat and is recom-
the buried outfall for a typical cold regions lagoon.
mended for intermittently operated systems. Where
A submerged outfall will be similar in concept to the
feasible, deep seepage pits are preferred over
water intake shown in figure 3-3.
conventional absorption fields because of their
greater thermal efficiency. In locations where in--
9-7. Alternatives to treatment/disposal.
ground disposal is not practical or feasible, vault
storage and truck haul will be required. Electric
At many remote installations that have small popu-
incinerator toilets have been successfully used since
lations or with intermittent usage, it may not be cost
1977 at remote Alaskan stations. These units are not
effective or technically feasible to construct one of
recommended for recreational areas or for transient
the treatment/disposal options discussed above.
users. The "grey water" (kitchen, bath and laundry
Small-scale on-site systems may be feasible for these
wastes) at these remote stations is discharged to a
situations and will be considered. Conventional
gravel pad on the ground surface.
septic tanks and soil absorption systems have been
used throughout Alaska with mixed results. Sludge