(2) Alternative power supply. If the existing power
supply is found to be unreliable, an emergency power supply or detention
facility shall be provided. Options include:
(A) electrical service from two separate commercial
power companies, provided automatic switchover capabilities are in
effect;
(B) electrical service from two independent feeder
lines or substations of the same electric utility, provided automatic
switchover capabilities are in effect;
(C) on-site automatic starting electrical generators;
(D) reliance on portable generators or pumps. Proposals
for the utilization of portable units shall be accompanied by a detailed
report showing conclusively the ability of such a system to function
satisfactorily. Portable units will be approved only in those cases
where the station is equipped with an auto-dialer, telemetry device,
or other acceptable operator notification device, operators knowledgeable
in acquisition and startup of the portable units are on 24-hour call,
the station is accessible in all weather conditions, reasonable assurances
exist as to the timely availability and accessibility of the proper
portable equipment, and the station is equipped with properly designed
and tested quick connection facilities. This option is usually acceptable
only for smaller lift stations.
(3) Restoration of lift station. Provisions should
be made to restore the lift station to service within four hours of
outage.
(4) Spill containment structures. A spill containment
structure should be considered together with in-system retention in
determining a total wastewater retention time. Because separate spill
retention facilities are not suitable for all locations, engineers
should check with the commission prior to designing such structures.
The design shall provide:
(A) a minimum storage volume of average design flow
from the contributing area and the longest power outage during the
most recent consecutive 24-month period or, if power records are not
available, an assumed 24-hour outage;
(B) an impermeable liner (such as concrete or synthetic
fabric (20 mil thickness)) and should have an energy dissipator at
the point of overflow from the lift station to prevent scour;
(C) a fence with a controlled access; and
(D) a plan for routine cleaning and inspection.
(5) Alarm system. An audiovisual alarm system (red
flashing light and horn) shall be provided for all lift stations.
These alarm systems should be telemetered to a facility where 24-hour
attendance is available. The alarm system shall be activated in case
of power outage, pump failure, or a specified high water level.
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