Current through Register Vol. 41, No. 3, September 23, 2024
A. Needs. Portable equipment (pumps or
generator sets) shall be acceptable to satisfy the continuous operability
requirements where, under critical conditions imposed by rush hour traffic,
multiple pumping station failures, etc., the portable equipment transportation,
connection and starting can be accomplished within allowable time periods.
1. Portable pumping equipment shall have the
following provisions:
a. Pumping units shall
have capability to operate between the wet well and the discharge side of the
station.
b. Each station served by
portable pumping equipment shall facilitate rapid and easy connection of
lines.
2. Numbers of
portable units and their pumping implementation capabilities that are
simultaneously available to service pumping stations, which are provided
continuous operability through the use of portable equipment, shall conform to
the following, whichever shall yield the greater number:
a. The number shall be the maximum number of
pumping stations (dependent on portable equipment for continuous reliability)
that are on the same radial extremity (single source feed) of any electrical
distribution circuit from the point of the radial extremity's intersection with
circuitry that has alternate feed.
b. The number shall be equal to 5.0% of the
number of pumping stations (dependent on portable equipment for continuous
reliability).
3. Volume
and head capabilities (pumps) or power watts (generators) of portable equipment
shall be capable, singly or in combination, of operating the largest pump
station dependent on portable equipment for continuous reliability.
B. Submittals. Plans and
specifications for a pump station submitted to the area engineer proposing to
use portable equipment to meet continuous operability requirements shall be
accompanied by a completed "Portable Equipment for Sewage Pump Stations" form.
A list of this information is included in
9VAC25-790-990.
1. The design submitted for sewerage systems
that utilize portable equipment to meet the continuous operability requirements
for sewage pump stations shall include the following information:
(i) an inventory of the owner's portable
equipment (pumps or generators) which lists numbers of units, capacities,
storage locations, and assignment of this equipment by the owner; and
(ii) an analysis of response times
based on geographical locations within the owner's sewerage system service
area.
2. The response
time analysis should be based upon a work crew responding to an alarm from the
pump station during the hour of the day that the peak flow to that station is
expected to be received.
C. Controlled diversion. The provision of a
high-level wet well-controlled diversion may be considered for pump stations of
all reliability classes.
1. If a high-level
wet well-controlled diversion is utilized, the overflow elevation shall be such
that the maximum feasible storage capacity of the wastewater collection system
shall be used before the controlled diversion is used. When a controlled
diversion is utilized at a Reliability Class I pumping station, it shall be to
a storage detention basin or tank. The storage volume shall be sized in
accordance with the pump station's operating conditions and the constraints and
conditions applicable to the owner's repair and maintenance capabilities. The
storage volume shall provide, without overflow, not less than six hours
detention capacity at the anticipated flow diversion rate.
2. Additional storage volume, or provisions
for protection against overflows in critical areas, may be required.
Statutory Authority
§ 62.1-44.19 of the Code of Virginia.
