5
benefit in that it needs minimal
compaction. Class II, naturally
rounded stone, may require
more compactive effort, or
tamping, to achieve the proper
density.
If the native soil condition
consists of clean, compactible
soil with less than 12% fines,
free of ice, rocks, roots, and
organic material, it may be
an acceptable backfill. Such
soil must be compacted in
lifts not to exceed one foot to
reach a final Proctor Density
between 85% and 90%. Non-
compactible clays and silts are
not
suitable backfill for this
or any underground structure
such as inlet or discharge
lines. If you are unsure of
the consistency of the native
soil, it is recommended that a
geotechnical evaluation of the
material be obtained before
specifying backfill.
Another option is the use of
a flowable fill (i.e., low slump
concrete). This is particularly
attractive when installing
grinder pump stations in
augured holes where tight
clearances make it difficult to
assure proper backfilling and
compaction with dry materials.
Flowable fills should not be
dropped with more than 4
feet between the discharge
nozzle and the bottom of the
hole because this can cause
separation of the constituent
materials.
6. VENTING:
The unit must
be properly vented to assure
correct operation of the pump.
The units are supplied with
a vent pipe from the wetwell
to the top of the accessway.
Failure to
properly vent
the tank will result in faulty
operation and will void the
warranty.
7. ELECTRICAL
CONNECTION: (Supply panel
to E/One alarm panel)
Before
proceeding, verify that the
service voltage is the same as
the motor voltage shown on the
name plate. An alarm device is
to be installed in a conspicuous
location where it can be readily
seen by the homeowner. An
alarm device is required on
every installation. There shall
be no exceptions.
Wiring of supply panel and
alarm panel shall be per
Figures 2a and 2b, alarm panel
wiring diagrams and local
codes. A dedicated 30 amp
breaker is required before a
240V duplex alarm panel, and
a dedicated 40 amp breaker is
required before a 120V duplex
alarm panel.
8. ELECTRICAL
CONNECTION: (Pump to
Panel) (Fig. 4)
The grinder
pump station is provided
with a cable for connection
between the station and the
alarm panel (supply cable).
The supply cable is shipped
inside the station with a small
portion fed through the cable
connector mounted on the
wall of the fiberglass shroud.
The supply cable, a six-
conductor tray cable, meets
NEC requirements for direct
burial as long as a minimum of
24” burial depth is maintained.
Those portions of the cable
that have less than 24” of
cover must be contained in
suitable conduit. This includes
the vertical portion dropping
to a 24” depth at the station
120 VOLT DUPLEX WIRING
Figure 2a
