Disinfection of Storage Facilities - Disinfection of Pipelines and Storage Facilities Field Guide - page 68

Full Storage Facility Chlorination Method
This method generally involves chlorinating the entire vol-
ume of the storage facility so that the water within the facility
has a residual chlorine concentration of at least 10 mg/L at the
end of the required retention period. Liquid chlorine, sodium
hypochlorite solution, or calcium hypochlorite tablets (or gran-
ules) are suitable for this procedure.
The chlorination process may involve a continuous fill of the
facility with chlorinated water with a concentration of at least
10 mg/L. Alternatively, the chlorination can be performed in two
steps: (1) adding the entire amount of chlorine to disinfect the
facility to a small amount of water covering the floor, and (2) filling
(after a holding period) the facility with potable water to achieve
10 mg/L throughout.

Liquid Chlorine
Liquid chlorine should be fed into the water filling the facility
so that the concentration is constant. Portable equipment includes
a liquid chlorine cylinder, a gas-flow chlorinator, a chlorine ejector,
safety equipment, and appropriate connections to inject the chlo-
rine solution into the fill stream. Trained operators are needed
for this operation. Safety regulations may require personnel certi-
fication for emergency response and first-aid training.

Sodium Hypochlorite
When using sodium hypochlorite solution, it should be added
to the feed water with a chemical feed pump or by pouring it into
the fill-stream. In each case, the solution is added to ensure ade-
quate mixing and to result in a constant chlorine concentration.
Convenient locations to pour sodium hypochlorite are the
cleanout or inspection manhole in the lower level of the facility,
the riser pipe of an elevated tank, or a roof manhole (Figure 5-1).
The hypochlorite solution should be poured in when the water is
1-3 ft deep, if possible.

Calcium Hypochlorite
Granules or tablets broken into small pieces (

in. or smaller)
can be added to the facility as previously described for the sodium

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