GB-75

Frequently Asked Questions

Are the Great Basin® indoor/outdoor units traffic rated (H-20 load rate)?

These units are traffic rated if they are installed in accordance with our installation instructions. The unit will need the T24-GI H-20 load-rated cast iron covers and a traffic-rated pad at grade per our installation detail.

Can corrugated pipe be used as a riser on the Great Basin® indoor/outdoor units?

No, corrugated pipe is not compatible with Great Basin® indoor/outdoor units. The available riser option is FP24 Fast Pitch® riser. Installing a corrugated pipe riser with this version of the Great Basin® units is not covered by the warranty.

Can the discharge from a food waste grinder be run through the Great Basin® indoor/outdoor units?

These units have solids capacity of 20% or more of the unit's liquid volume, but food waste grinders can quickly overwhelm a grease interceptor. If the food waste grinder is connected to the unit, we recommend a Billy Goat® solids interceptor in front of the grease interceptor.

Can the Great Basin® indoor/outdoor units be installed above grade (on the ground)?

All Great Basin® indoor/outdoor models can be installed above grade. The standoffs (4), which are provided standard, ensure the cover adapter(s) do not become unseated in the event of a downstream backup. A GB-500 installed above grade must also have the above grade support kit (AGS2).

Can the Great Basin® units be used with a dishwasher?

These units can be used with a dishwasher. If the dishwasher will have a discharge temperature higher than 150 degrees Fahrenheit, the system will require a drain tempering valve to reduce the water temperature.

Can you suspend the Great Basin® indoor/outdoor units with cover adapter(s) penetrating the floor above?

Yes, these units can be suspended with cover adapter(s) penetrating the floor above (with the exception of GB-1000 and GB-1500). The unit needs to be fully supported across the bottom with risers extending to the floor above. It is the responsibility of the specifying engineer or installer to design a support system appropriate for the weight of the unit with water. If suspending a GB-250, the unit must be installed with the above grade support kit (AGS1). If suspending a GB-500, the unit must be installed with the above grade support kit (AGS2).

Do the Great Basin® indoor/outdoor units need to be installed inside a vault to be buried in a high-water table area?

If the units will be installed in an area where the water table will crest the top of the tank shoulders, additional steps need to be taken to protect the unit from the extreme hydrostatic forces. The unit would need to be placed in a water tight vault or encased in concrete. If there is a possibility that ground water will come into contact with the unit, there needs to be a high-water/anti-flotation anchor kit installed (AK1, AK2, AK3).

Do the Great Basin® units require a fixture vent?

These units do not require a fixture vent. The internal design of the unit will ensure proper function without a fixture vent. Any venting to the piping connected to our unit is at the discretion of the local authority.

How much space is needed between units when they are installed in series?

There should be a minimum of 6" between the units when installed in series. In a buried application, this space will ensure there is enough backfill in between the units.

How can I view legacy products?

If you're looking for legacy products, please visit the Legacy Products page

Our fixture has an air gap and discharges into a floor sink, which is overflowing. How can we fix this?

Due to the low head pressure in this scenario, the first solution is to remove the internal flow control (applies only to Type C certified units with red flow control cartridge). This flow control cartridge is provided to ensure the maximum flow rate in GPM is not exceeded in basement applications, as the unit was certified to the ASME standard and not necessary in low flow applications. If that doesn’t solve the issue, the next solution is to add a flow restrictor to the tailpiece of the fixture. Contact support@schierproducts.com for more information.

How do I calculate how many risers I need for Great Basin® indoor/outdoor units?

The adjustable cover adapters that ship with these units offer up to 5" of built-in riser height. When more is needed, each Fast Pitch® riser section provides an additional 5" in height. Use our resources here to calculate how many risers you need based on either the distance from the top of the buried tank or the centerline of the buried tank.