Current through Register Vol. 47, No. 17, September 10, 2024
11.9(1) Applicability and Definitions
(a) For all surface water systems that use
conventional filtration treatment or direct filtration treatment and that also
recycle spent filter backwash water, thickener supernatant, or liquids from
dewatering processes, the supplier must comply with the requirements specified
in this rule.
(b) "LIQUIDS FROM
DEWATERING PROCESSES" means a stream of liquids generated from a unit used to
concentrate solids for disposal. Processes may consist of centrifuges, filter
presses, belt presses, vacuum filters, monofills, or other sludge concentrating
equipment. Such equipment may be used to dewater sludge from treatment units
used in recycling processes or sludge from units found in the primary
processes.
(c) "THICKENER
SUPERNATANT" means a stream of liquids containing the decant from a
sedimentation basin, clarifier or other unit that is used to treat water,
solids, or semi-solids from the primary treatment processes. The "clear water"
that exits the units after particles have been allowed to settle out is
thickener supernatant (or sludge thickener supernatant).
11.9(2)
Treatment Technique Requirement
for Filter Backwash Recycle
The supplier must return recycled spent filter backwash
water, thickener supernatant, or liquids from dewatering processes to a
location within the treatment process that is before the conventional
filtration treatment or direct filtration treatment or to an alternative
Department-approved location.
11.9(3)
Information Collection
Requirements for Filter Backwash Recycle
The supplier must collect all of the following information
about the recycle flow(s):
(a) A list
of all recycle flows and the frequency with which they are returned.
(b) The average and maximum backwash flow
rate through the filters.
(c) The
average and maximum duration of the filter backwash process in
minutes.
(d) The typical filter run
length and a written summary of how filter run length is determined.
(e) The type of treatment provided for the
recycle flow(s).
(f) If applicable,
data on the physical dimensions of the equalization and/or treatment units,
typical and maximum hydraulic loading rates, type of treatment chemicals used,
including the average dose and frequency of use, and frequency at which solids
are removed.
11.9(4)
Reporting Requirements for Filter Backwash Recycle
No later than 18 months after meeting the applicability of
this rule, the supplier must provide the Department with written notification
that includes all of the following:
(a) A plant schematic showing all of the
following:
(i) The origin of all flows which
are recycled.
(ii) The hydraulic
conveyance used to transport the flows.
(iii) The location where the flows are
re-introduced into the treatment plant.
(b) Typical recycle flow in gallons per
minute.
(c) The highest observed
plant flow experienced in the previous year in gallons per minute.
(d) Design flow for the treatment plant in
gallons per minute.
(e)
Department-approved operating capacity for the plant.
