b. If the hoses are to be cleaned on an apron, their end fittings are
attached to the inlet and outlet manifolds, forming loops by using U-bends
at the far end of the apron as described for the wash rack above. If the
washing apron is in the form of a wash trough located approximately 1 foot
from the hose storage rack, no more than two 50-foot lengths of hose should
be washed in the trough at one time, to prevent injury to personnel who
might walk on hoses when lifting lengths into storage on the rack.
c. The hoses should be flushed for two minutes with clear salt water
if available at the rack or apron, or with fresh water.
d. Following the two minute flush, a solution of calcium hypochlorite
(HTH) in fresh water is admitted to the hose lengths via the inlet manifold;
the disinfectant solution is mixed to contain one ounce of HTH powder per
50-foot length of hose. The chlorine solution is withdrawn from its tank by
means of an eductor in the fresh water supply line.
e. The disinfectant solution is left in the hoses for the 20 to 30
minutes required for disinfection. A small portion of the water in each
hose length is tested for chlorine residual at the end of the holding period;
if a residual exists, it is assumed that the hose has been disinfected. The
hose lengths then are drained to the sewer and flushed briefly with potable
water. After the flushing, the shore crew makes sure that each section of
hose has been drained properly. Then, a plastic dust cap is placed over the
male end, and a plastic dust plug is inserted into the female end of each
f. In cases where the chlorine test does not show a residual, it should
be assumed that there is a grease or possible pathogenic bacteria buildup
inside the hose length; the hose length is then cleaned internally with
detergent and flushed out. Chlorine solution is added as before; after the
20- to 30-minute contact period, the water within each hose length is tested
again for chlorine residual. If a chlorine residual exists, it can be
assumed that the hose has been disinfected; if no residual is found, the
detergent cleaning, flushing, and chlorinating steps are repeated until a
residual is obtained.
During the above cleaning procedures, the shore crew inspects each
length of hose for wear, damage, flaws, and malfunctions. Defective hoses
are set aside for repair or discard after they have been cleaned. When the
above steps have been completed the individual 50-foot lengths of hose are
clean and ready for storage.
Experience at San Diego to date has not shown a great accumulation in
any of the sewage transfer hoses. However, grease buildup problems exper-
ienced in ships' CHT systems provide grounds for the assumption that, at
some point in time, grease accumulation with resultant resistive contamina-
tion can be anticipated in the ships' hoses. Continuing work will be carried
out to establish improved cleaning and decreasing procedures for contaminated
sewage transfer hoses.