| (6) Where anhydrous ammonia feed equipment is utilized,
it must be housed in a separate enclosure equipped with both high
and low level ventilation to the outside atmosphere. The enclosure
must be provided with forced air ventilation which includes: screened
and louvered floor level and high level vents; a fan which is located
at and draws air in through the floor vent and discharges through
the top vent; and a fan switch located outside the enclosure. Alternately,
systems may install negative pressure ventilation as long as the facilities
also have gas containment and treatment as prescribed by the current
IFC.
(7) Chloramine disinfection shall be performed in a
manner which assures that the proper chlorine to ammonia (as nitrogen)
ratio is achieved in order to maintain a monochloramine residual and
limit nitrification.
(A) The order of chlorine and ammonia injection must
be accomplished in a manner which allows inactivation of viruses and
oxidation of cyanide.
(i) When chlorine is injected upstream of any other
disinfectant, the ammonia injection point must be downstream of the
chlorine injection point.
(ii) When chlorine and ammonia are added to distribution
water that has a chloramine residual, ammonia should be added first.
(iii) When chlorine and ammonia are added to distribution
water that has a free chlorine residual, chlorine should be added
first.
(B) Mixing shall be provided to disperse chemicals.
(C) Sampling taps must be provided at locations that
allow for chlorine and ammonia to be added to the water to form monochloramine
as the primary chloramine species. These locations must be listed
in the system's monitoring plan as described in §290.121 of this
title (relating to Monitoring Plans). Sample taps must be provided
as follows:
(i) upstream of the chlorine or ammonia chemical injection
point, whichever is furthest upstream;
(ii) between the addition of the chloramine chemicals
at chloramination facilities submitted for plan review after December
31, 2015. For these facilities, an installation without this sample
tap may be approved if an acceptable technical reason is described
in the plan review documents. Technical reasons, such as disinfection
byproduct control, must be supported by bench scale sampling results.
Other technical reasons, such as membrane integrity, must be supported
by documentation; and
(iii) at a point after mixing to be able to measure
fully-formed monochloramine levels.
(D) When using chloramines, the feed and storage must
be designed as described in subsection (f) of this section, regardless
of water source.
(E) When using chloramines, the public water systems
shall provide equipment for making at least the following determinations
for purposes of complying with the requirements in §290.110 of
this title:
(i) free ammonia (as nitrogen);
(ii) monochloramine;
(iii) total chlorine;
(iv) free chlorine; and
(v) nitrite and nitrate (both as nitrogen). The public
water systems must either obtain equipment for measuring nitrite and
nitrate or identify an accredited laboratory that can perform nitrite
and nitrate analysis and can provide results to the public water systems
within 48 hours of sample delivery.
(f) Water treatment plant chemical storage and feed
facilities.
(1) Chemical storage facilities shall be designed to
ensure a reliable supply of chemicals to the feeders, minimize the
possibility and impact of accidental spills, and facilitate good housekeeping.
(A) Bulk storage facilities at the plant shall be adequate
to store at least a 15-day supply of all chemicals needed to comply
with minimum treatment technique and maximum contaminant level (MCL)
requirements. The capacity of these bulk storage facilities shall
be based on the design capacity of the treatment plant. However, the
executive director may require a larger stock of chemicals based on
local resupply ability.
(B) Day tanks shall be provided to minimize the possibility
of severely overfeeding liquid chemicals from bulk storage facilities.
Day tanks will not be required if adequate process control instrumentation
and procedures are employed to prevent chemical overfeed incidents.
(C) Every chemical bulk storage facility and day tank
shall have a label that identifies the facility's or tank's contents
and a device that indicates the amount of chemical remaining in the
facility or tank.
(D) Dry chemicals shall be stored off the floor in
a dry room that is located above ground and protected against flooding
or wetting from floors, walls, and ceilings.
(E) Bulk storage facilities and day tanks must be designed
to minimize the possibility of leaks and spills.
(i) The materials used to construct bulk storage and
day tanks must be compatible with the chemicals being stored and resistant
to corrosion.
(ii) Except as provided in this clause, adequate containment
facilities shall be provided for all liquid chemical storage tanks.
(I) Containment facilities for a single container or
for multiple interconnected containers must be large enough to hold
the maximum amount of chemical that can be stored with a minimum freeboard
of six vertical inches or to hold 110% of the total volume of the
container(s), whichever is less.
(II) Common containment for multiple containers that
are not interconnected must be large enough to hold the volume of
the largest container with a minimum freeboard of six vertical inches
or to hold 110% of the total volume of the container(s), whichever
is less.
(III) The materials used to construct containment structures
must be compatible with the chemicals stored in the tanks.
(IV) Incompatible chemicals shall not be stored within
the same containment structure.
(V) No containment facilities are required for hypochlorite
solution containers that have a capacity of 55 gallons or less.
(VI) On a site-specific basis, the executive director
may approve the use of double-walled tanks in lieu of separate containment
facilities.
(F) Chemical transfer pumps and control systems must
be designed to minimize the possibility of leaks and spills.
(G) Piping, pumps, and valves used for chemical storage
and transfer must be compatible with the chemical being fed.
(2) Chemical feed and metering facilities shall be
designed so that chemicals shall be applied in a manner which will
maximize reliability, facilitate maintenance, and ensure optimal finished
water quality.
(A) Each chemical feeder that is needed to comply with
a treatment technique or MCL requirement shall have a standby or reserve
unit. Common standby feeders are permissible, but generally, more
than one standby feeder must be provided due to the incompatibility
of chemicals or the state in which they are being fed (solid, liquid,
or gas).
(B) Chemical feed equipment shall be sized to provide
proper dosage under all operating conditions.
(i) Devices designed for determining the chemical feed
rate shall be provided for all chemical feeders.
(ii) The capacity of the chemical feeders shall be
such that accurate control of the dosage can be achieved at the full
range of feed rates expected to occur at the facility.
(iii) Chemical feeders shall be provided with tanks
for chemical dissolution when applicable.
(C) Chemical feeders, valves, and piping must be compatible
with the chemical being fed.
(D) Chemical feed systems shall be designed to minimize
the possibility of leaks and spills and provide protection against
backpressure and siphoning.
(E) If enclosed feed lines are used, they shall be
designed and installed so as to prevent clogging and be easily maintained.
(F) Dry chemical feeders shall be located in a separate
room that is provided with facilities for dust control.
(G) Coagulant feed systems shall be designed so that
coagulants are applied to the water prior to or within the mixing
basins or chambers so as to permit their complete mixing with the
water.
(i) Coagulant feed points shall be located downstream
of the raw water sampling tap.
(ii) Coagulants shall be applied continuously during
treatment plant operation.
(H) Chlorine feed units, ammonia feed units, and storage
facilities shall be separated by solid, sealed walls.
Cont'd... |
