Environmental Engineering Reference
In-Depth Information
The pipeline diameter and length.
600-mm diameter and 2,000-m length
Valves, hydrants, tees, and other appurtenances.
No valves or hydrants are listed in this job.
Volume of chlorination water to disinfect pipeline.
Select a 20% slug from Table 3-12 because 16 hr are
available and a 20% slug will take 15 hr to complete.
The volume of the slug is calculated from c3-6.
2,000
×
282.6
×
0.2 = 113,040 L
Amount of chlorine needed to complete the disinfection
procedure.
5% sodium hypochlorite feed rate to match
withdrawal rate of 628 L/min or 10.5 L/s is 1,260
mL/min (from Table 3-11). The withdrawal rate and
the fill rate are the same. It takes 3 hr (180 min) to
create the 20% slug, so 1,260
180 = 226,800 mL or
226.8 L of 5% sodium hypochlorite is needed for the
job.
×
Calculate the withdrawal rate using c3-7.
113,040 ÷ 180 = 628 L/min for 3-hr contact time
along the pipeline.
References
ANSI/AWWA C651. AWWA Standard for Disinfecting Water
Mains . American Water Works Association: Denver, Colo.
Standard Methods for the Examination of Water and Wastewater .
(current edition). APHA, AWWA, WEF: Washington, D.C.
Tikkanen, M., and J. Schroeter. 2001. Guidance Manual for
Disposal of Chlorinated Water , Awwa Research Foundation:
Denver, Colo.
Water Transmission and Distribution , 3rd ed. 2004. American
Water Works Association: Denver, Colo.
Zhang, Jian. Guidelines to Minimize Downtime During Pipe
Lining Operations , Awwa Research Foundation preliminary
draft. University of Louisville, AWWA: Denver, Colo.
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