Pipeline Chlorination Simplified - Disinfection of Pipelines and Storage Facilities Field Guide - page 118

Simplified Slug Method for Larger Pipelines
The simplified method assumes a slug that is 20% of the total
length of the pipeline to be disinfected. Also, the rate that the
slug is moved along the pipeline is such that the contact time is
3 hr at every point. Limiting the procedure to these parameters
reduces the calculations to only three steps.
1. Calculator c8-3 is used to calculate the volume of the 20%
slug. The length of the pipeline and the appropriate value
from Table 8-3 are used in this calculation.
2. Next, calculator c8-4 is used to determine the withdrawal
rate (the rate that water is moved along the pipeline to
achieve the necessary 3-hr contact time). The volume of
the 20% slug calculated in step 1 is divided by the 180
minutes (3 hr). The withdrawal rate (same as fill rate) is
also used to find the matching chlorine solution feed rate
for the 1% or 5% strength solution.
3. The volume of 1% chlorine solution needed to prepare the
20% slug with a dosage of 100 mg/L is calculated using
c8-5. This is the amount of 1% solution that needed to be
on hand (add about 25% extra for contingencies) to com-
plete the procedure.

Limiting the variables and using this three-step process
greatly simplifies a process that can become confusing and com-
plex. Examine the examples below to gain further insight regard-
ing how to use this procedure.

Volume of Chlorination Water to Disinfect the Pipeline

Volume of 20 percent slug calculator.

(c8-3)

Total length
of pipe to be
disinfected

Volume/ft or
volume/m
(from Table 8-3)

Volume of
20% slug

= × × 0.2