Schier GB-75 User manual

Contents
Special Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Getting to Know the GB-75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
INSTALLATION GUIDE
GB-75 75 GPM Great Basin™Indoor/Outdoor Grease Interceptor
913-951-3300 | schierproducts.com
© Copyright 2022 Schier Products Company, 11/21/22
LIFETIME GUARANTEED GREASE INTERCEPTORS

SPECIAL PRECAUTIONS
Do not install this unit in any manner
except as described in these instructions.
Doing so may result in property damage, personal injury or death.
DO NOT AIR TEST UNIT OR RISER SYSTEM!
For Schier Grease Interceptor Installations - Failure to follow this guidance voids
your warranty
Provide at least 16" clearance
above unit for routine
maintenance.
16" min.
Install interceptor as close as possible to
fixtures being served
Installation Instructions
Installation instructions and additional
components are included with the interceptor.
Read all instructions prior to installation. This
interceptor is intended to be installed by a
licensed plumber in conformance with all local
codes.
High Temperature Kitchen Water
If water is entering the interceptor at excessive temperature (over 150º F), a
drain water tempering valve (DTV) and approved backflow prevention assembly
must be installed. Most state and local plumbing codes prohibit water above
150º F being discharged into the sanitary sewer. Water above 150º F will
weaken or deform PVC Schedule 40 pipe, poly drainage fixtures like
interceptors and erode the coating of cast iron (leading to eventual failure).
Suspended Installations
Design trapeze to support the wet weight
of the unit. Do not partially support unit or
suspend unit using metal U-channel to
create a trapeze.
concrete floor
Support Inlet and Outlet Piping
For above grade installations ensure heavy
inlet and outlet piping (such as cast iron or
long runs) is properly supported or
suspended during the entire installation
process to prevent connection failure or
damage to bulkhead fittings.
pipe supports
ODOR ALERT!
Interceptor is not a
sewer gas trap.
All upstream fixtures
must be trapped
ODOR ALERT!
Do not install air
gap on outlet side
of interceptor.
DO NOT USE CAST IRON
COVERS IN ABOVE GRADE OR
INDOOR INSTALLATIONS
Use composite cover C24BC for above
grade installations
Fully Support Base of Unit
Install unit on solid, level surface in contact
with the entire footprint of unit base
Schier | GB-75 Installation Guide
page 2 of 10page 2 of 10

SPECIAL PRECAUTIONS
For Schier Grease Interceptor Installations - Failure to follow this guidance voids your
warranty
Below Grade Installation Slab Requirements
A concrete slab to finished grade with rebar is required when installing
interceptor below grade.
Pedestrian Trac or
Greenspace Areas
Vehicular Trac Areas
4" min. slab 8" min.
slab
Hydrostatic/
Pressure Slabs
When installed under a
hydrostatic slab (slab designed
to withstand upward lift, usually
caused by hydrostatic
pressure) interceptor must be
enclosed in a watertight
concrete vault.
concrete slab subject to hydrostatic pressure
watertight
concrete
vault
High Water Table Installations
Interceptors and risers are not designed
to withstand water table height in excess
of the top of the unit when buried (see
figure). If it is possible for this to occur,
install the interceptor and risers in a
water-tight concrete vault or backfill with
concrete or flowable fill (wet concrete
and flowable backfill should be poured
in stages to avoid crushing the
interceptor). At risk areas include but are
not limited to tidal surge areas,
floodplains and areas that receive storm
water. Great Basin™models that are
direct buried in high water table scenarios must be installed with an anchor kit.
Model GB-75 uses model AK1 anchor kit.
DO NOT
COMPACT BACKFILL
MECHANICALLY
Compact by
hand only
max water table height for
direct burial
model AK1
anchor kit
Secure Cover Adapters
Cover adapters must be secured to
base units in above grade installations
with increased head pressure
conditions. Use cover adapter tie-down
kit model ATD1.
RebarRebar
Max Water Level
Risers are not designed
to retain water
Installations with Risers
Corrugated Riser Pipe
Requirements
Riser adapter model CA2 must be used
when installing interceptors using 24"
diameter corrugated pipe as a riser.
This will adequately embed the cover
adapter in the concrete slab, preventing
cover/cover adapture failure under
trac rated loads.
CA2
3 FCR2 Risers Max
94"
94"
6 - 94"6 - 94"
Schier | GB-75 Installation Guide
page 3 of 10

GETTING TO KNOW THE GB-75
1. Pickable cast iron cover (standard)
2. Cover gasket
3. Safety Star® access restrictor
4. Safety Star® tether
5. Cover adapter
6. Cover adapter gasket assembly with
upper and lower stainless steel band
clamps
7. 4" cleanout plug (x2)
8. Outlet bulkhead connection (optional) 4"
FPT (x2)
9. Bulkhead connection gasket
10. Bulkhead connection retaining nut
11. Inlet diuser cover (white)
12. Inlet diuser
13. Inlet diuser retaining nut
14. Inlet diuser foot retaining nut
15. Inlet diuser (foot)
16. Inlet bulkhead connection 4" FPT
17. 4" plain end fitting (x2)
18. Composite cover bolts
and washers (x4)
19. Bolted composite cover (optional)
20. Air relief/visual access
21. Outlet diuser retaining nut
22. Outlet diuser
23. Outlet diuser foot retaining nut
24. Outlet diuser (foot)
25. Outlet bulkhead connection (standard)
4" FPT
26. 7/16" nut driver bit
1 18
19
20
21
22
23
24
10
9
8
7
2
3
5
6
7
8
9
10
13
12
15
14
10
9
16
17
26
4
10
17
9
25
Schier | GB-75 Installation Guide
page 4 of 10
11
Inlet diuser
cover (white)

1Test tank for water tightness
1a 1b
1c
Have a Leak?
Call customer care at 913-951-3300
Hours 8am-5pm CST, M-F
Cap all connection points with 4" cleanout plugs using
pipe thread sealant or tape approved for use with
plastics.
Remove cover. For base unit testing fill with water to just above
the highest connection.
Inspect unit, connections and gaskets for leaks. Check water
level at specific time intervals per local code.
Fill Line
Schier | GB-75 Installation Guide
page 5 of 10
Excavate hole at least 12" larger than interceptor on all sides and 6" deeper than tank bottom. Lay a level bed of well-packed,
crushed aggregate (approximately 3/4" size rock or sand, with no fines) in the base of hole.
12" 12"
6" 6" or more
2 Excavate Burial Pit

Schier | GB-75 Installation Guide
page 6 of 10
3 Set Up Outlet Diuser and Install Cleanout Plugs
Screw in provided 4" cleanout plugs using pipe thread sealant or
tape approved for use with plastics. Do not cap the inlet or outlet
connections attached to the diusers.
3a Choose outlet location.
3c Cap unused connections(all configurations)
Side Outlet:
Go to Step 3b.
Straight
Through:
Go to Step 3c.
3b Reposition outlet diuser (side outlets only)
Remove safety star insert, leave tethered to unit. Unscrew diuser retaining nut and remove outlet diuser.
Unscrew diuser foot retaining nut and remove outlet diuser foot. Rotate diuser toward chosen outlet, replace
foot ensuring it will point to the back wall of the unit and hand tighten foot retaining nut. Insert diuser into chosen
outlet and hand tighten retaining nut.

Schier | GB-75 Installation Guide
page 7 of 10
This unit is supplied with a white inlet diuser cover to
prevent the unit from swamping in high flow/ increased
head pressure conditions.
• If dimension "A" is 13 feet or less, the inlet diuser
cover is not needed, go to Step 5, Connect Piping.
• If dimension "A" is more than 13 feet, or a high
flow/increased head pressure condition exists,
follow Steps below.
4 Install Inlet Diuser Components
Remove Safety Star® insert and remove inlet diuser cover from the parts bag. Slide inlet diuser cover into
top of inlet diuser and rotate clockwise until cartridge drops onto the inlet diuser cover retainer pins.
Continue rotating clockwise until pins are fully seated.
4a Install inlet diuser cover
For easy inlet diuser cover removal
in deep burial installations, 1-1/2"
PVC SCH. 40 pipe may used as an
extension handle. Before risers
have been installed, cut pipe to
length and attach to top of cover
using PVC primer/cement.
Extension handle length should be
about 12" shorter than total riser
height.
4b OPTIONAL: install extension handle
Finished installation
showing optional
extension handle
inlet diuser cover
retainer pin
cartridge receiver
slot

Schier | GB-75 Installation Guide
page 8 of 10
5a Install plain end fittings
5b Connect interceptor to drain lines
5 Connect Piping
4" Plain End
Screw plain end fittings (included) into bulkhead fittings using pipe thread sealant or tape approved for
use with plastics. 6" connection types come pre-installed from the factory.
Place unit into final position and set level. Mechanically couple inlet and outlet drainage lines to unit. Do not
solvent weld. Ensure all upstream fixtures are trapped. Vent per local code. Installation of 2-way cleanout tees to
grade (by others) is recommended for buried installations.
Outlet
2-way
cleanout tee
Inlet
BURIED INSTALLATION
Kitchen floor
Add this vent if unit is installed one
or more floors below the fixtures
being served
Vent per local code
FLOOR BELOW INSTALLATION
COUPLING DETAIL
Drain line
Flexible coupling
Plain end fitting
Bulkhead fitting
4" FPT4" FPT

6 Wet or Air Test Piping Per Local Code
Doing so may result in property damage, personal injury or death.
DO NOT AIR TEST UNIT OR RISER SYSTEM! Have a Leak? Call customer care
at 913-951-3300
Hours 8am-5pm CST, M-F
Schier | GB-75 Installation Guide
page 9 of 10
7 Bring Covers Flush-to-Grade
The GB-75 is ready for burial depth of 40" from finished grade to bottom of tank (or 13-1/2" to centerline of inlet).
Deeper burials will require extending the cover adapters and possibly adding risers.
Measure dimension X to determine riser height needed.
7a
See instructions included with FCR2.
Riser Height Risers
Needed Required
0" - 4" None (use adapter)
>4" - 34" FCR2 (x1)
>34" - 64" FCR2 (x2)
>64" - 94" FCR2 (x3)
Loosen the cover adapter upper band clamp
using 7/16" Nut Driver Bit. Adjust cover adapter
heights as needed. Maintain a minimum
2-1/2" insertion depth. Tighten upper band
clamp to 5 -8 ft. lbs. of torque using 7/16" nut
driver Bit. If required, cover adapters may now
be tilted up to 10º in any direction using gasket
flexibility.
7c Make final cover adapter adjustments
7b Install risers if required
COVER ADAPTER ADJUSTMENT DETAIL
2-1
/
2" minimum
Cover
Safety Star
access restrictor
Cover adapter
Gasket
Upper band clamp
Lower band clamp
Interceptor accessway

DO NOT COMPACT BACKFILL
Schier | GB-75 Installation Guide
page 10 of 10
8 Install Anti-Flotation Anchor Kit
9 Backfill and Finished Grade
Fill unit with water for stabilization and float-out prevention. Backfill evenly around tank using crushed aggregate (approximately 3/4" size
rock or sand with no fines)or flowable fill. Do not compact backfill around unit.
9a Backfill
If the installation location is in a high
water table or at risk area (including but
not limited to tidal surge areas,
floodplains and areas that receive storm
water) the GB-75 must be installed with
Schier model AK1 anchor kit.
Max water table height for direct burial
Model AK1 anchor kit
Vehicular Trac Areas:
Minimum 8" thick concrete slab with rebar required. Thickness of concrete around covers to be determined by
specifying engineer. If trac loading is required the concrete slab dimensions shown are for guideline
purposes only. Concrete to be 28 day compressive strength to 4,000 PSI. Use No. 4 rebar (ø 1/2") grade 60
steel per ASTM A615: connected with tie wire. Rebar to be 2-1/2" from edge of concrete and spaced in a 12"
grid with 4" spacing around access openings.
Pedestrian Trac or Greenspace Areas:
Minimum 4" thick concrete slab with rebar required.
TOP VIEW 18"
min
45º
18"
min
18"
min
18"
min
Concrete slab
Rebar
9b Pour concrete slab to finished grade
Rebar