| (F) development of procedures whereby portions of the
pressure system may be rerouted with temporary lines in the event
of leaks, construction, or repair.
(3) Pipe selection. Appropriate ASTM, ANSI, or AWWA
standards shall be specified for alternative wastewater collection
system pipe and joints. Pipe which will be used in pressure sewer
systems shall have a minimum sustained working pressure rating of
150 pounds per square inch gauge as per appropriate standard. Pipe
selection shall also conform to subsection (a)(1) - (3) and (5) of
this section.
(4) Leakage testing. All alternative wastewater collection
systems components shall be tested for leakage. Testing procedures
for on-site system components, small diameter gravity sewer systems,
and vacuum sewer systems will be approved on a case-by-case basis.
Pressure sewer installation shall be tested for leakage with a hydrostatic
test. Copies of all test results shall be made available to the executive
director upon request. Leakage in the pressure sewer hydrostatic test
shall be defined as the quantity of water that must be supplied into
the pipe or any valved section thereof to maintain pressure within
five pounds per square inch of the specified test pressure after the
air in the pipeline has been expelled. The test pressure shall be
either a minimum of 25 pounds per square inch gauge or 1.5 times the
maximum force main design pressure, whichever is larger. The maximum
allowable leakage shall be calculated using the formula in this paragraph.
If the quantity of leakage exceeds the maximum amount calculated,
remedial action shall be taken to reduce the leakage to an amount
within the allowable limit as follows.
Attached Graphic
(5) Pumps. Pumping units and grinder pumps used in
pressure sewer systems should be reliable, easily maintained, and
should have compatible characteristics.
(A) Pumps and grinder pump units shall be provided
with two backflow prevention devices (one check valve at tank, to
protect against back drainage into tank, second check valve at connection
of service line to pressure collection line to protect against leaking
sewage in case service line is damaged) and shall be easily accessible
for maintenance.
(B) Sufficient holding capacity shall be provided in
the pumping compartment to allow for wastewater storage during power
outages and equipment failures. Storage volume should be based on
power supply outage records and replacement equipment availability.
(C) Pumping units shall not be installed in the settling
chamber of an interceptor tank if the interceptor tank is to be used
for solids reduction.
(D) Alarms, warning lights, or other suitable indicators
of unit malfunction shall be installed at each pumping station.
(E) Whenever any pumping station handles waste from
two or more residential housing units or from any public establishment,
dual pump units shall be provided to assure continued service in the
event of equipment malfunction.
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