Page 42 - Water and Wastewater Engineering Design Principles and Practice

THE DESIGN AND CONSTRUCTION PROCESSES 1-13

TABLE 1-3
Guidance for minimum equipment and process reliability for water treatment
Component Recommendation
Source
Surface water
Capacity Meet a one-in-50-year drought with due consideration for multiple year
droughts
Intake structures Where intake tower is used, provide two independent intake cells, each
with three intake ports at different elevations
Pumps Minimum of two; meet the maximum day demand with one unit out of
service
Groundwater
Capacity Equal or exceed maximum day demand with largest producing well out
of service
Wells Minimum of two
Treatment

Rapid mix Minimum of two; meet the maximum day demand with one unit out of
service
Flocculation Minimum of two; meet the maximum day demand with one unit out of
service
Sedimentation Minimum of two; meet the maximum day demand with one unit out of
service
Disinfection Minimum of two; meet the maximum day demand with one unit out of
service
Power Provide primary transmission lines from two separate sources or
standby generator
Finished water storage

Capacity Equal to the average day demand when fire protection is not provided
Meet domestic demand and fire flow demand where fire protection is
provided
Distribution
High service pumps Minimum of two; meet the maximum day demand with one unit out of
service
System pressure Minimum of 140 kPa at ground level at all points in the system
Nominal working pressure should be 410 to 550 kPa and not less than
240 kPa
Sources: Foellmi, 2005; GLUMRB, 2003.