|(a) All irrigation distribution systems or water distribution
systems into which any type of chemical (except disinfecting agents)
or other foreign substances will be injected into the water pumped
from water wells shall be equipped with an in-line, automatic quick-closing
check valve capable of preventing pollution of the ground water. The
required equipment shall be installed on all systems whenever a pump
is installed or repaired, or at the time of a chemical injection,
Chemigation or foreign substance unit is added to a water delivery
system, if the well has a chemical injection, Chemigation, or foreign
substance unit in the delivery system. The type of check valve installed
shall meet the specifications listed in subsections (b) - (h).
(b) The body of the check valve shall be constructed
of cast iron, stainless steel, cast aluminum, cast steel, or of a
material and design that provides a sturdy integrity to the unit and
is resistant to the foreign substance being injected. All materials
shall be corrosion resistant or coated to prevent corrosion. The valve
working pressure rating shall exceed the highest pressure to which
the valve will be subjected.
(c) The check valve shall contain a suitable automatic,
quick-closing and tight-sealing mechanism designed to close at the
moment water ceases to flow in the downstream or output direction.
The device shall, by a mechanical force greater than the weight of
the closing device, provide drip-tight closure against reverse flow.
Hydraulic backpressure from the system does not satisfy this requirement.
(d) The check valve construction should allow for easy
access for internal and external inspection and maintenance. All internal
parts shall be corrosion resistant. All moving parts shall be designed
to operate without binding, distortion, or misalignment.
(e) The check valve shall be installed in accordance
with the manufacturer's specifications and maintained in a working
condition during all times in which any fertilizer, pesticide, chemical,
animal waste, or other foreign substance is injected into the water
system. The check valve shall be installed between the pump discharge
and the point of chemical injection or foreign substance injection.
(f) A vacuum-relief device shall be installed between
the pump discharge and the check valve in such a position and in such
a manner that insects, animals, floodwater, or other pollutants cannot
enter the well through the vacuum-relief device. The vacuum-relief
device may be mounted on the inspection port as long as it does not
interfere with the inspection of other anti-pollution devices.
(g) An automatic low pressure drain shall also be installed
between the pump discharge and the check valve in such a position
and in such a manner that any fluid which may seep toward the well
around the flapper will automatically flow out of the pump discharge
pipe. The drain must discharge away from rather than flow into the
water supply. The drain must not collect on the ground surface or
seep into the soil around the well casing.
(1) The drain shall be at least three-quarter (3/4)
inch in diameter and shall be located on the bottom of the horizontal
pipe between the pump discharge and the check valve.
(2) The drain must be flush with the inside surface
of the bottom of the pipe unless special provisions, such as a dam
made downstream of the drain, forces seepage to flow into the drain.
(3) The outside opening of the drain shall be at least
two (2) inches above the grade.
(h) An easily accessible inspection port shall be located
between the pump discharge and the check valve, and situated so the
automatic low-pressure drain can be observed through the port and
the flapper can be physically manipulated.
(1) The port shall allow for visual inspection to determine
if leakage occurs past the flapper, seal, seat, and/or any other components
of the checking device.
(2) The port shall have a minimum four (4) inch diameter
orifice or viewing area. For irrigation distribution systems with
pipe lines too small to install a (4) inch diameter inspection port,
the check valve and other anti-pollution devices shall be mounted
with quick disconnects, flange fittings, dresser couplings, or other
fittings that allow for easy removal of these devices.
(i) Any check valve not fully meeting the specifications
set forth in this section may on request to the executive director
be considered for a variance.