HomeMy WebLinkAboutStaff Report 178-07City o f Palo Alto
City Manager’s Report
TO:HONORABLE CITY COUNCIL
FROM:CITY MANAGER DEPARTMENT: UTILITIES
DATE:
SUBJECT:
April 9, 2007.CMR:178:07
PALO ALTO WATER MAIN DISTRIBUTION SYSTEM FLUSHING
PROGRAM - STATUS REPORT
This is an information report and no Council action is required.
BACKGROUND
Historically, the City of Palo Alto and approximately 85 percent of water utilities in the
United States use main flushing to improve water quality for water customers. Water
utilities may flush distribution mains for a variety of reasons: corrosion control, sediment
removal, taste and odor control, control of color, to reduce turbidity, to reduce chlorine
residuals, or to reduce bacteriological growths, or as a response to customer complaints.
The main objectives of Palo Alto’s flushing program are to improve water quality, control
bacterial growth and remove built-up sediment. ,
Between 1990 and 1993, the Palo Alto Water Utility did not perfolan an annual main
flushing program because of the drought. During this period, customer water
consumption was also reduced, thereby accelerating sediment buildup in the mains.
During 1992, numerous calls were received complaining about water quality. At that
time, staff took water samples in response to these calls and found that the reduced water
quality was due to the buildup of sediment in the mains. Also, City Fire Department
personnel found more sediment in their equipment from the City’s water system during
1992. Water Operations staff flushed mains every year between 1993 and 2003.. Staff
did not receive water quality complaints due to sediment build up in the distribution
mains during that period because of the success of the annual water distribution system
flushing program. Between 2004 and the present, the water distribution has not been
flushed on an annual basis primarily because of an insufficient number of staff to
dedicate to the project.
CMR:178:07 Page 1 of 2
DISCUSSION
As a result of improved staffing levels, beginning April 22, 2007 and continuing through
April 28, 2007, the City’s Water Utility Operations Section will open fire hydrants to
flush out sediment that has collected in the mains during the past 3 years. Flushing of the
mains may cause some slight, but temporary, reduction in water pressure and possible
water discoloration.
Residents will see fire hydrants and blow-off valves opened by staff and used as flush-out
points from the distribution system mains. Water flushed from hydrants and blow-off
valves is dechlorinated and discharged to clean street surfaces, flush storm drains, or is
used to clean sanitary sewers. It is not practical to attempt to recapture this water for re-
use for irrigation, filling residential swimming pools or other purposes. The water system
main flushing map and schedule will be displayed in the Palo Alto Weekly, Palo Alto
Daily, City Internet Home Page, and scrolling messages on the Midpeninsula Community
Media Center (MCMC) community public access channels.
ATTACHMENTS
2007 Water System Flushing Schedule and Map
PREPARED BY:An Le, Engineer
Romel Antonio, Sr. Project Engineer
Greg Scoby, Acting Engineering Manager
Roger Cwiak, Acting Asst. Director, Utilities
DEPARTMENT HEAD:
CITY MANAGER APPROVAL:
City Manager
CMR:178:07 Page 2 of 2
=ril 26
April 23
10:00 pm
April 28
FridayApril 27
Monday Night
April 23
10:00 pm
CITY OF PALO ALTO
UTILITIES
Saturda~
April 28
The City of Palo Alto Utilities will begin flushing the
water distribution system Sunday, April 22, 2007
and will continue through Saturday, April 28, 2007.
Flushing may be extended by a few days, as needed.
Utilities Operations will open fire hydrants to flush
out sediment that has collected in the mains during
the past year.
Flushing of the mains may cause some slight, but
temporary, reduction in water pressure and possible
water discoloration. If you experience discolored
water, stop using water indoors and run the
connection closest to the street (usually the front
hose bib) for I 0 minutes onto your landscaping to
Friday
April 27
Saturday
April 28
flush sediment from your house line. Your water
remains absolutely safe for drinking.
We suggest that you refrain from doing laundry
while the water lines are being flushed in your area.
If you live near any area border, please refrain from
doing laundry while the water lines are being flushed
in your area and the adjacent area.
The amount of water released during the system
flushing does not pose a threat of flooding.
However, if a threat of flooding due to inclement
weather should occur during the flushing schedule,
the flushing operations will be suspended until
further notice.
on;Utilities