Optimal Corrosion Control Treatment Permits/ Chemical Feed
Permits
Supplies Which Meet the Optimal Corrosion Control Treatment Calculation
Optimal Corrosion Control Treatment (OCCT) is in place whenever the value
of the 90th percentile sample result, minus the value of the highest entry point
sample result, equals less than the Practical Quantitation Level (PQL) [90th
percentile sample - Entry Point Sample = <5 ppb]. Any supply which meets the
calculation for optimal corrosion control for two consecutive six month sampling
periods is required only to submit water quality samples. Based upon these samples,
the Agency will establish water quality parameter ranges by Special Exception
Permit (SEP), and will reduce the number of sampling sites for both faucet and
water quality samples to the reduced monitoring schedule. This schedule will
remain in place until eligible for further reduction or unless the Action Level
is exceeded.
Establishing Water Quality Parameters for Lead & Copper
Once a supply has either met the OCCT formula for two consecutive sampling
periods or has installed corrosion control treatment, been deemed to have optimized
corrosion control by the Agency and completed follow-up monitoring, the Agency
will specify water quality parameters by Special Exception Permit (SEP). The
Agency establishes minimums or ranges initially to accommodate temperature fluctuations
and changes in water quality, and will adjust those levels as needed upon its
own volition or upon request of the public water supply. Only those water quality
parameters which are adjusted for purposes of corrosion control will be established.
Other water quality compliance parameters, such as trihalomethane and CT requirements,
will be taken into consideration when parameter minimums or ranges are established.
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