Disinfection for Pipeline Repairs - Disinfection of Pipelines and Storage Facilities Field Guide - page 59

protect these materials while they are in storage. Pipe and other
parts should be stored in a manner to avoid casual water and dirt
from entering. Any visible foreign matter should be removed
from the interior of stored repair parts. Watertight end caps or
other protective coverings should be used and maintained to pre-
vent possible contamination.

Sanitary Repair Practices
Care should be taken to prevent water, dirt, and other material
from entering the damaged pipeline. Surface water should be
diverted from the construction site using barriers if necessary.
The excavation should be dewatered so that water is below the
pipe invert (Figure 4-1). Before beginning a repair, the interior of
the pipe should be cleaned where it has contacted the soil or
backfill material. Soil beyond reach can be removed by low velocity
flushing in both directions. If possible, the flow or positive pres-
sure should be maintained in the leaking pipeline to prevent
backflow of contaminated water. This is particularly important
until the leak is exposed and secured.

Ops T ip Take special care to keep the pipe clean. This will make

disinfection more effective.

Repair crews need to be aware that their actions could con-
taminate the water supply during a pipeline repair. Crews must
ensure the cleanliness of all cables, pipes, and hoses drawn
through the inside of the pipelines or appurtenances. Disinfec-
tion (using chlorine dip or swab solutions) of hand tools (such as
saws) used in the repair is a prudent step. Equipment operators
should also use caution to avoid introducing soil or other mate-
rial into the repaired pipeline.

Chlorination Procedures
When an existing main is opened because of a break or leak,
the excavation is usually wet and may be contaminated. ANSI/
AWWA Standard C651, Disinfecting Water Mains , requires the
application of liberal amounts of hypochlorite to the open trench