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

Radionuclides (40 CFR 141.26 and WAC 246-290-300 (8))
The new radionuclides rule (effective December 2003) requires monitoring for gross alpha,
radium 226, radium 228, and uranium. This monitoring is conducted for each source at the entry
point to the distribution system. Frequency is dependent on results. Two consecutive quarterly
samples were collected before December 2007 for initial monitoring. After initial monitoring,
samples will likely be required once every 9 years.
Fluoride (WAC 246-290-460)
As required by state regulations, fluoride is monitored daily at each point of fluoride addition and
a report is submitted to the state monthly. For process control purposes, fluoride concentration is
monitored continuously with an online instrument. In addition to fluoride monitoring at the
treatment plants, a grab sample is collected daily and analyzed at SPU’s Water Quality
Laboratory as a check. Results for one monthly check sample are submitted to the state.
Unregulated Contaminants Monitoring Rule (40 CFR 141.35, 40)
The Unregulated Contaminants Monitoring Rule requires additional monitoring for SPU’s source
waters. For UCMR 2, four quarterly samples were collected at the entry point to the distribution
system in 2009. The next projected UCMR monitoring (UCMR 3) is projected to occur between
2013 and 2015.
Groundwater Rule (40 CFR 141.400 - 405)
This regulation was finalized in late 2006, with an effective date of December 1, 2009. Only the
Riverton and Boulevard Park Wells are subject to this regulation. SPU has decided to use
triggered source water monitoring for the compliance strategy. This means a source water E.
Coli sample will need to be collected from the wells any time the wells are in operation, and a
TCR compliance sample from the area fed by the wells is positive. The sample must be
collected within 24 hours notice.
Cryptosporidium Monitoring for LT2SWTR (40 CFR 141, Subpart W)
SPU currently conducts quarterly source water monitoring for Giardia and Cryptosporidium for
the Cedar and Tolt supplies. This monitoring is currently voluntary. Monthly monitoring to
determine compliance with LT2SWTR was completed in 2007. The results of Cryptosporidium
monitoring are reported in the annual Drinking Water Quality Report sent to customers each
year. Currently, samples are collected from two locations: Tolt Regulating Basin outlet (TPR-4),
and Lake Youngs outlet (C1-Raw) prior to treatment. The next round of monthly monitoring for
LT2SWTR compliance is required six years after completion of the previous round (possibly
2013 or 2014).
Comprehensive Water Quality Monitoring Plan Page 6 of 12