Washington Administrative Code
Title 246 - Health, Department of
WATER SYSTEMS
Chapter 246-290 - Group A public water supplies
Part 6 - SURFACE WATER TREATMENT
Subpart C - Requirements for Systems Installing Filtration Facilities
Section 246-290-676 - Filtration technology and design criteria
Universal Citation: WA Admin Code 246-290-676
Current through Register Vol. 24-18, September 15, 2024
(1) General.
(a) The purveyor proposing to construct new
water treatment facilities or to make additions to existing water treatment
facilities for surface and GWI sources shall ensure that the facilities comply
with the treatment, design, and reliability requirements of Part 6 of chapter
246-290 WAC.
(b) The purveyor shall
submit an engineering report to the department describing how the treatment
facilities will be designed to comply with the requirements specified in
Sub-parts A, B, and C of Part 6 of chapter 246-290 WAC.
(2) Filtration technology.
(a) The purveyor shall select a filtration
technology acceptable to the department using criteria such as those outlined
in department guidance on surface water treatment. The following filtration
technologies are considered acceptable:
(i)
Conventional;
(ii)
Direct;
(iii) Diatomaceous earth;
and
(iv) Slow sand.
(b) In addition to the
technologies specified in subsection (2)(a) of this section, alternative
filtration technologies may be acceptable, if the purveyor demonstrates to the
department's satisfaction all of the following:
(i) Through acceptable third party testing,
that system components do not leach or otherwise add substances to the finished
water that would violate drinking water standards, or otherwise pose a threat
to public health;
(ii) The
technology's effectiveness in achieving at least 99 percent (2-log) removal of
Giardia lamblia cysts or cyst surrogate particles, and at
least 99 percent (2-log) removal of Cryptosporidium oocysts or
oocyst surrogate particles. The purveyor shall further demonstrate the
technology's removal capability through research conducted:
(A) By a party acceptable to the department;
and
(B) In accordance with protocol
and standards acceptable to the department.
(iii) Through on-site pilot plant studies or
other means, that the filtration technology:
(A) In combination with disinfection
treatment consistently achieves 99.9 percent (3-log) removal and inactivation
of Giardia lamblia cysts and 99.99 percent (4-log) removal and
inactivation of viruses; and
(B)
Meets the applicable turbidity performance requirements as determined by the
department for the specific treatment process being considered, but in no case
to exceed 1.0 NTU for the finished water.
(3) Pilot studies.
(a) The purveyor shall ensure pilot studies
are conducted for all proposed filtration facilities, except where waived based
on engineering justification acceptable to the department.
(b) The purveyor shall obtain department
approval for the pilot study plan before the pilot filter is constructed and
before the pilot study is undertaken.
(c) The pilot study plan shall identify at a
minimum:
(i) Pilot filter design;
(ii) Water quality and operational parameters
to be monitored;
(iii) Type of data
to be collected, frequency of data collection, and length of pilot study;
and
(iv) Pilot plant operator
qualifications.
(d) The
purveyor shall ensure that the pilot study is:
(i) Conducted to simulate proposed full-scale
design conditions;
(ii) Conducted
over a time period that will demonstrate the effectiveness and reliability of
the proposed treatment system during changes in seasonal and climatic
conditions; and
(iii) Designed and
operated in accordance with good engineering practices and that ANSI/NSF
standards 60 and 61 are considered.
(e) When the pilot study is complete, the
purveyor shall submit a project report to the department for approval under WAC
246-290-110.
(4) Design criteria.
(a) The purveyor shall ensure that water
treatment facilities for surface and GWI sources are designed and constructed
in accordance with good engineering practices documented in references such as
those identified in WAC
246-290-200.
(b) Filtration facilities.
(i) The purveyor shall ensure that all new
filtration facilities and improvements to any existing filtration facilities
(excluding disinfection) are designed to achieve at least 99 percent (2-log)
removal of Giardia lamblia cysts, and 99 percent (2-log)
removal of Cryptosporidium oocysts; and
(ii) The purveyor shall ensure that all new
filtration facilities contain provisions for filtering to waste with
appropriate measures for backflow prevention.
(c) The purveyor shall ensure that
disinfection systems for new filtration facilities or improvements to existing
disinfection facilities are designed to meet the requirements of WAC
246-290-662.
Statutory Authority: RCW 70.119A.180 and 43.20.050. 08-03-061, § 246-290-676, filed 1/14/08, effective 2/14/08. Statutory Authority: RCW 43.20.050(2) and (3) and 70.119A.080. 03-08-037, § 246-290-676, filed 3/27/03, effective 4/27/03. Statutory Authority: RCW 43.02.050 [43.20.050]. 99-07-021, § 246-290-676, filed 3/9/99, effective 4/9/99. Statutory Authority: RCW 43.20.050. 93-08-011 (Order 352B), § 246-290-676, filed 3/25/93, effective 4/25/93.
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