Haw. Code R. § 11-20-10 - Turbidity sampling and analytical requirements
(a)
Samples shall be taken by suppliers of water for public water systems using
surface water sources in whole or in part. Turbidity measurements shall be made
by the Nephelometric Method 2130B cited in the 18th edition of Standard Methods
for the Examination of Water and Wastewater, 1992, or by the methods cited in
40 C.F.R. §
141.74(a)(1).
(b) The requirements in this subsection apply
to filtered surface water systems until June 29, 1993. The requirements in this
subsection apply to unfiltered systems until June 29, 1993, or until filtration
is installed, whichever is later. The director shall determine, in writing
pursuant to
42 U.S.C. §
300g-1(b)(7)(C)(iii), which
systems must install filtration.
(1) Samples
shall be taken by suppliers of water for public water systems using surface
water sources in whole or in part. Samples shall be taken at a representative
entry point(s) to the water distribution system at least once per day, for the
purpose of making turbidity measurements to determine compliance with section
11-20-5.
If the director determines that a reduced sampling frequency in a non-community
system will not pose a risk to public health, the director may reduce the
required sampling frequency. The option of reducing the turbidity frequency
shall be permitted only in those public water systems that practice
disinfection and which maintain an active residual disinfectant in the
distribution system, and in those cases where the director has indicated in
writing that no unreasonable risk to health existed under the circumstances of
this option.
(2) If the result of
a turbidity analysis indicates that the maximum allowable limit has been
exceeded, the sampling and measurement shall be confirmed by resampling as soon
as practicable and preferably within one hour. If the repeat sample confirms
that the maximum allowable limit has been exceeded, the supplier of water shall
report to the director within forty-eight hours. The repeat sample shall be the
sample used for the purpose of calculating the monthly average. If the monthly
average of the daily samples exceeds the maximum allowable limit, or if the
average of two samples taken on consecutive days exceeds five NTU, the supplier
of water shall report to the director and notify the public as directed in
sections
11-20-17 and
11-20-18.
(c) After June 29, 1993, samples
shall be collected at the filtration plant effluent or immediately prior to
entry into the distribution system. Sampling of the plant effluent is
acceptable if there are no storage tanks between the sampling point and entry
into the distribution system. Continuous monitoring with a turbidimeter and
recording chart, or collection of grab samples every four hours is required for
conventional treatment, direct, and diatomaceous earth
filtration.
Notes
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