Current through Register Vol. 24-18, September 15, 2024
(1) The purveyor shall operate filters so
that maximum flow rates do not exceed those specified in Table 14 of this
section. The purveyor may operate filters at higher flow rates, if the purveyor
demonstrates to the department's satisfaction that filtration at the higher
rate consistently achieves at least 99 percent (2-log) removal of
Giardia lamblia cysts and 99 percent (2-log) removal of
Cryptosporidium oocysts and meets the turbidity performance
requirements of Table 15.
Table 14
FILTRATION OPERATION CRITERIA
|
FILTRATION TECHNOLOGY/MEDIA
|
MAXIMUM FILTRATION RATE
(gpm/ft2) |
|
Conventional, Direct and In-Line |
|
Gravity Filters with Single Media |
3 |
|
Gravity Filters with Deep Bed, Dual or Mixed
Media |
6 |
|
Pressure Filters with Single Media |
2 |
|
Pressure Filters with Deep Bed, Dual or Mixed
Media |
3 |
|
Slow Sand |
0.1 |
|
Diatomaceous Earth |
1.0 |
(2) The purveyor using conventional, direct
or in-line filtration shall ensure that effective coagulation is in use at all
times the water treatment facility produces water served to the
public.
(3) The purveyor using
conventional, direct, or in-line filtration shall demonstrate treatment
effectiveness for Giardia lamblia cyst and
Cryptosporidium oocyst removal by one of the following
methods:
(a) Turbidity reduction method.
(i) The purveyor shall make source and
filtered water turbidity measurements in accordance with WAC
246-290-664(2) and
(3) respectively.
(ii) The purveyor shall achieve:
(A) The turbidity performance requirements
specified in WAC
246-290-660(1)
and at least an eighty percent reduction in source turbidity based on an
average of the daily turbidity reductions measured in a calendar month;
or
(B) An average daily filtered
water turbidity less than or equal to 0.1 NTU.
(b) Particle counting method. The purveyor
shall:
(i) Use a particle counting protocol
acceptable to the department; and
(ii) Demonstrate at a frequency acceptable to
the department at least the following log reduction of particles in the size
range of five to fifteen microns (
Giardia lamblia cyst-sized
particles) and three to five microns (
Cryptosporidium
oocyst-sized particles), as applicable:
(A)
2.5-log reduction in Giardia lamblia cyst-sized particles and
a 2-log reduction in Cryptosporidium particles for systems
using conventional filtration; or
(B) 2.0 log reduction for systems using
direct or in-line filtration.
(c) Microscopic particulate analysis method.
The purveyor shall:
(i) Use a protocol
acceptable to the department; and
(ii) Demonstrate at a frequency acceptable to
the department at least the following log reduction of
Giardia lamblia
cysts and
Cryptosporidium oocysts or
Giardia
lamblia cyst and
Cryptosporidium oocyst surrogate
indicators as applicable:
(A) 2.5-log
reduction in Giardia lamblia cysts or surrogates and a 2-log
reduction in Cryptosporidium oocyst or surrogates for systems
using conventional filtration; and
(B) 2.0 log reduction for systems using
direct or in-line filtration.
(d) Other methods acceptable to the
department.
(4) The
purveyor shall provide continuous disinfection of all water delivered to the
public and shall:
(a) Maintain an adequate
supply of disinfection chemicals and keep back-up system components and spare
parts on hand;
(b) Develop,
maintain, and post at the water treatment facility a plan detailing:
(i) How water delivered to the public will be
continuously and adequately disinfected; and
(ii) The elements of an emergency
notification plan to be implemented whenever the residual disinfectant
concentration at entry to distribution falls below 0.2 mg/L for more than one
hour.
(c) Implement the
plan during an emergency affecting disinfection.
(5) Operations program.
(a) For each water treatment facility
treating a surface or GWI source, the purveyor shall develop an operations
program and make it available to the department for review upon
request.
(b) The program shall be
submitted to the department as an addendum to the purveyor's water system plan
(WAC 246-290-100) or small water
system management program (WAC 246-290-105).
(c) The program shall detail how the purveyor
will produce optimal filtered water quality at all times the water treatment
facility produces water to be served to the public.
(d) The purveyor shall operate the water
treatment facility in accordance with the operations program.
(e) The operations program shall include, but
not be limited to, a description of:
(i) For
conventional, direct or in-line filtration, procedures used to determine and
maintain optimized coagulation as demonstrated by meeting the requirements of
WAC 246-290-654(3);
(ii) Procedures used to determine chemical
dose rates;
(iii) How and when each
unit process is operated;
(iv) Unit
process equipment maintenance program;
(v) Treatment plant performance monitoring
program;
(vi) Laboratory
procedures;
(vii)
Records;
(viii) Reliability
features; and
(ix) Response plans
for water treatment facility emergencies, including disinfection failure and
watershed emergencies.
(f) The purveyor shall ensure the operations
program is:
(i) Readily available at the
water treatment facility for use by operators and for department
inspection;
(ii) Consistent with
department guidelines for operations procedures such as those described in
department guidance on surface water treatment and water system planning;
and
(iii) Updated as needed to
reflect current water treatment facility operations.
(6) Pressure filters. Purveyors
using pressure filters shall:
(a) Inspect and
evaluate the filters, at least every six months, for conditions that would
reduce their effectiveness in removing Giardia lamblia
cysts;
(b) Maintain, and make
available for department review, a written record of pressure filter
inspections; and
(c) Be prepared to
conduct filter inspections in the presence of a department representative, if
requested.
Statutory Authority:
RCW
70.119A.180 and
43.20.050. 08-03-061, §
246-290-654, filed 1/14/08, effective 2/14/08. Statutory Authority:
RCW
43.20.050(2) and (3) and
70.119A.080. 03-08-037, §
246-290-654, filed 3/27/03, effective 4/27/03. Statutory Authority: RCW
43.02.050 [43.20.050]. 99-07-021, § 246-290-654, filed 3/9/99, effective
4/9/99. Statutory Authority:
RCW
43.20.050. 94-14-001, § 246-290-654,
filed 6/22/94, effective 7/23/94; 93-08-011 (Order 352B), § 246-290-654,
filed 3/25/93, effective 4/25/93.
