| (a) Capacity. The minimum clearwell, storage tank,
and pressure maintenance capacity shall be governed by the requirements
in §290.45 of this title (relating to Minimum Water System Capacity
Requirements).
(b) Location of clearwells, standpipes, and ground
storage and elevated tanks.
(1) No public water supply elevated storage or ground
storage tank shall be located:
(A) within 500 feet of any;
(i) municipal or industrial sewage treatment plant;
(ii) land which is spray irrigated with sewage treatment
plant effluent; or
(iii) land on which sewage treatment plant sludge,
septic tank sewage sludge, or biosolids is applied; or
(B) within 150 feet of any land spray irrigated with
effluent from onsite sewage facilities as defined in §285.2 of
this title (related to Definitions).
(2) Insofar as possible, clearwells or treated water
tanks shall not be located under any part of any buildings and, when
possible, shall be constructed partially or wholly above ground.
(3) No storage tank or clearwell located below ground
level is allowed within 50 feet of a sanitary sewer or septic tank.
However, if the sanitary sewers are constructed of 150 pounds per
square inch (psi) pressure-rated pipe with pressure-tested, watertight
joints as used in water main construction, the minimum separation
distance is ten feet.
(4) No storage tank or clearwell located below ground
level is allowed within 150 feet of a septic tank soil absorption
system.
(c) Design and construction of clearwells, standpipes,
ground storage tanks, and elevated tanks. All facilities for potable
water storage shall be covered and designed, fabricated, erected,
tested, and disinfected in strict accordance with current American
Water Works Association (AWWA) standards and shall be provided with
the minimum number, size and type of roof vents, man ways, drains,
sample connections, access ladders, overflows, liquid level indicators,
and other appurtenances as specified in these rules. The roof of all
tanks shall be designed and erected so that no water ponds at any
point on the roof and, in addition, no area of the roof shall have
a slope of less than 0.75 inch per foot.
(1) Roof vents shall be gooseneck or roof ventilator
and be designed by the engineer based on the maximum outflow from
the tank. Vents shall be installed in strict accordance with current
AWWA standards and shall be equipped with approved screens to prevent
entry of animals, birds, insects and heavy air contaminants. Screens
shall be fabricated of corrosion-resistant material and shall be 16-mesh
or finer. Screens shall be securely clamped in place with stainless
or galvanized bands or wires and shall be designed to withstand winds
of not less than tank design criteria (unless specified otherwise
by the engineer).
(2) All roof openings shall be designed in accordance
with current AWWA standards. If an alternate 30-inch diameter access
opening is not provided in a storage tank, the primary roof access
opening shall not be less than 30 inches in diameter. Other roof openings
required only for ventilating purposes during cleaning, repairing
or painting operations shall be not less than 24 inches in diameter
or as specified by the licensed professional engineer. An existing
tank without a 30-inch in diameter access opening must be modified
to meet this requirement when major repair or maintenance is performed
on the tank. Each access opening shall have a raised curbing at least
four inches in height with a lockable cover that overlaps the curbing
at least two inches in a downward direction. Where necessary, a gasket
shall be used to make a positive seal when the hatch is closed. All
hatches shall remain locked except during inspections and maintenance.
(3) Overflows shall be designed in strict accordance
with current AWWA standards. If the overflow terminates at any point
other than the ground level, it shall be located near enough and at
a position accessible from a ladder or the balcony for inspection
purposes. The overflow(s) shall be sized to handle the maximum possible
fill rate without exceeding the capacity of the overflow(s). The discharge
opening of the overflow(s) shall be above the surface of the ground
and shall not be subject to submergence. The discharge opening shall
be covered with a gravity-hinged and weighted cover, an elastomeric
duckbill valve, or other approved device to prevent the entrance of
insects and other nuisances. When the tank is not overflowing, the
cover shall close automatically and fit tightly with no gap over 1/16
inch.
(4) All clearwells and water storage tanks shall have
a liquid level indicator located at the tank site. The indicator can
be a float with a moving target, an ultrasonic level indicator, or
a pressure gauge calibrated in feet of water. If an elevated tank
or standpipe has a float with moving target indicator, it must also
have a pressure indicator located at ground level. Pressure gauges
must not be less than three inches in diameter and calibrated at not
more than two-foot intervals. Remote reading gauges at the owner's
treatment plant or pumping station will not eliminate the requirement
for a gauge at the tank site unless the tank is located at the plant
or station.
(5) Inlet and outlet connections shall be located so
as to prevent short-circuiting or stagnation of water. Clearwells
used for disinfectant contact time shall be appropriately baffled.
(6) Clearwells and potable water storage tanks shall
be thoroughly tight against leakage, shall be located above the groundwater
table, and shall have no walls in common with any other plant units
containing water in the process of treatment. All associated appurtenances
including valves, pipes, and fittings shall be tight against leakage.
(7) Each clearwell or potable water storage tank shall
be provided with a means of removing accumulated silt and deposits
at all low points in the bottom of the tank. Drains shall not be connected
to any waste or sewage disposal system and shall be constructed so
that they are not a potential agent in the contamination of the stored
water. Each clearwell or potable water storage tank must be designed
to drain the tank.
(8) All clearwells, ground storage tanks, standpipes,
and elevated tanks shall be painted, disinfected, and maintained in
strict accordance with current AWWA standards. However, no temporary
coatings, wax grease coatings, or coating materials containing lead
will be allowed. No other coatings will be allowed which are not approved
for use (as a contact surface with potable water) by the United States
Environmental Protection Agency, NSF International (NSF), or United
States Food and Drug Administration. All newly installed coatings
must conform to American National Standards Institute/NSF (ANSI/NSF)
Standard 61 and must be certified by an organization accredited by
ANSI.
(9) No tanks or containers shall be used to store potable
water that have previously been used for any nonpotable purpose. Where
a used tank is proposed for use, a letter from the previous owner
or owners must be submitted to the executive director which states
the use of the tank.
(10) Access manways in the riser pipe, shell area,
access tube, bowl area or any other location opening directly into
the water compartment shall be located in strict accordance with current
AWWA standards. These openings shall not be less than 24 inches in
diameter. However, in the case of a riser pipe or access tube of 36
inches in diameter or smaller, the access manway may be 18 inches
times 24 inches with the vertical dimension not less than 24 inches.
The primary access manway in the lower ring or section of a ground
storage tank shall be not less than 30 inches in diameter. Where necessary,
for any access manway which allows direct access to the water compartment,
a gasket shall be used to make a positive seal when the access manway
is closed.
(d) Design and construction of pressure (hydropneumatic)
tanks. All hydropneumatic tanks must be located wholly above grade
and must be of steel construction with welded seams except as provided
in paragraph (8) of this subsection.
(1) Metal thickness for pressure tanks shall be sufficient
to withstand the highest expected working pressures with a four to
one factor of safety. Tanks of 1,000 gallons capacity or larger must
meet the standards of the American Society of Mechanical Engineers
(ASME) Section VIII, Division 1 Codes and Construction Regulations
and must have an access port for periodic inspections. An ASME name
plate must be permanently attached to those tanks. Tanks installed
before July 1, 1988, are exempt from the ASME coding requirement,
but all new installations must meet this regulation. Exempt tanks
can be relocated within a system but cannot be relocated to another
system.
(2) All pressure tanks shall be provided with a pressure
release device and an easily readable pressure gauge. When more than
one pressure tank is connected by a common manifold pipe and pressure
switch to allow the tanks to operate as a single unit, the unit shall
be provided at least one pressure gauge.
Cont'd... |
