Pipeline Chlorination Simplified - Disinfection of Pipelines and Storage Facilities Field Guide - page 110

Chlorination Checklist
❑ The pipeline diameter and length.
❑ Valves, hydrants, tees, and other appurtenances.
❑ Volume of chlorination water to disinfect pipeline (this is the volume
for disposal; chlorine residual is needed to determine dechlorination
chemical amount needed).
❑ Amount of chlorine chemical needed to complete the disinfection
procedure.
Pipelines Less Than 12 in. (300 mm)
The continuous feed method (in Chapter 3) is the most com-
mon for pipes less than 6-in. (150-mm) diameter; however, many
utilities use this method for 12-in. pipes. The amount of chlori-
nated water needed for these small pipes is manageable and the
method is effective. A 25 mg/L chlorine solution is used to fill the
pipeline. After 24 hr, the residual must be at least 10 mg/L. Both
calcium hypochlorite and sodium hypochlorite are commonly
used to prepare the 25 mg/L chlorination solution. Liquid chlo-
rine is not usually used for this purpose (although it is accept-
able) because of safety considerations when handling chlorine
cylinders in the field.
Follow the procedures in Chapter 3 for the continuous-feed
method. Cleaning the pipeline before beginning the disinfection
process is most important. Use Table 8-1 to prepare 25 mg/L feed
solution using calcium hypochlorite or sodium hypochlorite.
Make sure that the solution is thoroughly mixed prior to feeding
into the pipeline. Dechlorinate the discharge, if necessary,
according to procedures in Chapter 7.
To use this method, all that is needed is the volume of the
pipeline. From this and using the tables and calculators, the
amount of chlorine chemical can be determined and, if necessary,
the dechlorination requirements can be calculated. The method
requires a 25 mg/L dosage, so this is used in the chlorine amount
calculator. Follow these steps: