Solution to Slug Method Disinfection Problem

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The pipeline to be chlorinated is 6in diameter and 800 ft long.

The pipeline volume per foot is 3.14 x .25 x .25 x 1 ft x 7.48 gal/ft = 1.47 gallons/ft of pipeline

To disinfect the pipeline we want a 100 mg/L chlorine dosage in contact for 3 hours.

We want to finish the job in less than 8 hours so we will need a slug that is about 40% of the entire volume.

A 40% slug is 800 ft x .4 = 320 ft

The volume of the slug is 320 ft x 1.47 gallons/ft = 470 gallons

The withdrawal rate is 470 gallons/180 min = 2.6 gpm

The amount of 1% sodium hypochlorite needed to make 470 gallons of 100 mg/L solution is
470*100 = x*10000   or 4.7 gallons

Chlorinate the valves and hydrants with a calcium hypochlorite tablet each.


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Bill