Pipeline Chlorination Simplified - Disinfection of Pipelines and Storage Facilities Field Guide - page 120

❑ Amount of chlorine needed to complete the disinfection

procedure.
Using calculator c8-5, 1% sodium hypochlorite =
1,224 gal 0.01 = 12.24 gal

1 gal of 10% sodium hypochlorite is needed to make
10 gal of 1% so 1.2 gal of 10% is needed to make
12.24 gal of 1% solution

×

The withdrawal rate for a 20% slug (c8-4) = 1,224 gal ÷
180 min (3 hr) = 6.8 gal/min
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☞

1% sodium hypochlorite feed rate from Table 8-5 is 4.2 g/hr
for 7 gpm fill rate. This will result in a chlorine dosage slightly
higher than 100 mg/L.

Example 2. Create a 20% slug of 100 mg/L chlorine con-
centration for a 500-mm diameter pipeline. Disinfect 1,000 m
of new pipeline. What is the water withdrawal rate that will
result in at least a 3-hr contact time along the pipeline? If 1%
hypochlorite solution (prepared from calcium hypochlorite) is
injected to form the slug, what is the feed rate?
Use the checklist to ensure all of the information is collected.
❑

The pipeline diameter and length.
500-mm diameter and 1,000-m length

Valves, hydrants, tees, and other appurtenances.
No valves or hydrants are listed.

❑

Volume of chlorination water to disinfect pipeline
Using calculator c8-3, volume = 1,000 m

❑

196.25 L/m

×

0.2 = 39,250 L

×

Amount of chlorine needed to complete the disinfection
procedure.
Using calculator c8-5, 1% hypochlorite = 39,250 L

❑

×

0.01 = 390 L
1 lb of 65% calcium hypochlorite is needed to make
8 gal of 1% solution, so 454 g or 0.454 kg is needed
for (3.785 8) 30.28 L of 1% solution. Therefore,

0.454 kg/30.28L

×

390 L = 5.8 kg

×