2013 Water System Plan, Volume II - Seattle City Clerk's Office - City ...

Stage 2 Rule will be based on locational running annual averages instead of system wide running
annual averages.
Lead and Copper Rule (40 CFR 141.80-91)
SPU has conducted monitoring for lead and copper at customers’ taps according to the
regulations and a Bilateral Compliance Agreement with DOH. Two rounds of samples were
collected at 375 homes in 2003 and 2004 after completion of a corrosion control optimization
study for the Tolt. Two more rounds of samples were collected at 400 homes in 2005. These
homes were selected based on criteria in the Lead and Copper Rule. For the last two rounds, the
homes were divided into sub regions. One hundred samples were collected from the Seattle
direct service area, 100 were collected from Bellevue, 100 were collected from the participating
wholesale providers receiving water from the Cedar supply, and 100 were collected from the
participating wholesale providers receiving water from the Tolt supply. Compliance was based
on the 90 th percentile for each sub-region. Based on previous rounds, each sub-region qualifies
for reduced monitoring, which requires 50 samples per sub-region. Each sub-region is currently
required to collect 50 samples once every three years. Monitoring requirements would change if
the lead or copper action levels were exceeded. The Cedar wholesale provider group will collect
samples in 2012, Seattle direct service area will collect samples in 2013, and the Tolt wholesale
provider group will collect samples again in 2014.
Water quality parameter monitoring at the treatment plants and within the distribution system is
also now required for the lead and copper rule. Monitoring of pH is required at the Cedar Water
Treatment Facility and both pH and alkalinity is required at the Tolt Water Treatment Facility.
The distribution system monitoring currently includes collecting 10 samples each month and
analyzing the samples for pH and alkalinity. The 10 locations are distributed throughout the
direct service area and Cedar and Tolt wholesale sub-regions that are part of the regional
monitoring program.
Inorganic Contaminants, VOCs, SOCs (40 CFR 141.23-23, 40 and WAC 246-290-
300 (4) and (7))
Primary and Secondary inorganic contaminants (IOCs), volatile organic chemicals (VOCs), and
synthetic organic chemicals (SOCs) are monitored according to state and federal requirements.
IOCs for the Cedar and Tolt supplies are monitored on an annual basis and VOCs are monitored
once every three years, with the samples collected from the entry point to the distribution system,
after treatment. This frequency assumes a state waiver has been granted for VOCs. The
Riverton and Boulevard Park Wells are sampled once every three years (or when in operation)
for IOCs and VOCs at the entry point to the distribution system prior to the first customer. SOCs
are monitored as directed by the state, and the frequency is dependent on waiver status. SOCs
were last collected in 2008. The year 2011 marks the beginning of a new three and nine year
monitoring period. State waivers have not yet been issued for this monitoring period.
Comprehensive Water Quality Monitoring Plan Page 5 of 12