Disinfection of Pipelines - Disinfection of Pipelines and Storage Facilities Field Guide - page 47

Use the checklist to ensure all of the information is collected.

❑ The pipeline diameter and length.

200-mm diameter and 500-m length

❑ Valves, hydrants, tees, and other appurtenances.

No valves or hydrants in job description

❑ Volume of chlorination water to disinfect pipeline.

From Table 3-6, 6-in. pipe contains 31.40 L/m, so
500 m contains 15,700 L. At 3 L/s fill rate, the
procedure will take about 87 min.

❑ Amount of chlorine needed to complete the disinfection

procedure.
From Table 3-9b, 153 m of 200-mm pipe requires
12.3 L of 1 percent sodium hypochlorite solution, so
for 500 m (12.3 500 ÷ 152), 39.5 L is needed.

×

Complete the procedure by matching (calculating using
c3-5) the chlorine solution feed rate with the pipeline fill rate
(3 L/sec in this case).

☞

Chlorine
solution feed
rate (mL/min)

Water fill
rate (L/sec)
total

Strength of
chlorine feed
solution (%)

= 150 ×

÷

mL/min = 150 3 ÷ 1 = 450 mL/min feed rate for

×

25 mg/L dosage

Slug Method
The slug method requires that a section of new main is highly
chlorinated, then valves are operated and water is slowly
removed from the end of the main causing the “slug” of highly
chlorinated water to move along the newly installed pipeline
(Figure 3-15). As this slug passes tees, crosses, and hydrants, the
adjacent valves are operated to ensure the disinfection of all
appurtenances and branches.
The slug method generally involves placing calcium hypochlo-
rite granules or tablets in the main during construction; filling