HomeMy WebLinkAboutAgenda Report - February 17, 2010 J-01AGENDA ITEM J40
CITY OF LODI
COUNCIL COMMUNICATION
Im
AGENDA TITLE: Receive Report On Drinking Water Chlorination
MEETING DATE: February 17,2010
PREPARED BY: PublicWorks Director
RECOMMENDED ACTION: Receive report on drinking water chlorination.
BACKGROUND INFORMATION: The Public Works Department is bringing this matterto the City
Council to highlight regulatory and operational changes in the water
utility. Although no City Council action is sought, this item is
intended to inform the public of these changes.
Lodi has a long history of providing groundwaterfree of chlorinationto the public. Forthe last two years,
however, the PublicWorks Department has added small amounts of chlorine to the City's drinking water
supply at a handful of well sites to minimize bacteria detections and meet state drinking water standards.
In late November, a sample tested positive for bacteria. Furthersampling was negative, and no additional
action was needed. PublicWorks staff noted, however, that no residual chlorine had been detected in the
City's water supply since August, despite its application at five to six well sites. This lack of residual
chlorine may have allowed the bacteria to survive in the water system.
Although health regulators are not requiring the City to regularly chlorinate the water supply, this positive
bacteria test in November coincided with the onset of a new federal groundwater regulation. Beginning
December 1, 2009, a positive bacteria test in the water supply requires additional tests from all 26 of the
City's wells within 24 hours, according to the U.S. Environmental Protection Agency's Ground Water
Rule. Previously, only the immediate upstream and downstream sampling points required testing, in
addition to the original sampling site.
As a result of the new regulation and recent sample results, PublicWorks is increasing the amount of
chlorine to the system and the number of wells where the treatment is being applied. This new regulation
places an operational and cost burden on the water utility that reduces the benefit of trying to operate
without chlorination. Adding low levels of chlorine to the drinking water is a cost-effective way to limitthe
amount of follow-up testing that would otherwise be required when samples test positivefor bacteria. The
amount of additional chlorine is the minimum needed to keep the water system bacteria -free.
FISCAL IMPACT: It costs a minimum of $950 to test all of the City's wells within 24 hours,
requiring 18 staff hours. This assumes staff availability and no overtime.
Wally Sa elin
PublicWorks Director
APPROVED:
King, City Manager
Receive Report
Drinking Water Chlorination
Lodi City Council
Regular Meeting
February 17, 2010
Background
Historically, Lodi's drinking water has been
relatively free of chlorine
Intermittent chlorine dosing has occurred
. Taste and odor control
. Positive coliform results
Typical chlorine dosage has been 1.0 ppm
with a system residual goal of .4 ppm
2
20
18
16
14
12
10
8
6
4
2
0
Annual Positive Total Coliform Samples
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
New
Drinking Water Regulation
)�Groundwater Rule
. Objective — Provide enhanced protection
against microbial pathogens in public water
systems
. Effective - December 2009
. Directive - Increase source monitoring
51
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Chlorination Plan
)�� Goals
. Minimize / eliminate positive coliform results
. Minimize source monitoring sampling
)�� Establish a minimum chlorine residual of
0.05 to 0. 10 ppm