Question of the Week: Can a pump be installed in a two compartment IM-Series septic tank when a sealed pump chamber is not required?

Each week our technical services team fields hundreds of calls into our tech line. We’ve been getting this question quite often: Can a pump be installed in a two compartment IM-Series septic tank when a sealed pump chamber is not required?

First, you must confirm with the local regulatory code to make sure this tank configuration is allowed by code. If so, this guidance is intended for a single tank application in which a pump or pump vault is installed within a two compartment Infiltrator IM-Series Septic Tank (septic tank and pump tank within the same tank). The baffle wall is not sealed and cannot be sealed. As is the case with any single tank system that incorporates a pump it is good practice to have smaller pump doses. A smaller pump dose volume will minimize the pulling of solids through to the second compartment.

For example:  A 1 to 2” drawdown in liquid level is recommended. Set Aquaworx Control Panel or float system accordingly.

• IM-1060 a 1” drawdown equals a 25-gallon pump dose. A 2” drawdown equals a 50-gallon pump dose.
• IM-1530 a 1” drawdown equals a 35-gallon pump dose. A 2” drawdown equals a 71-gallon pump dose.

Please check the local regulatory code as it may require a minimum dose volume. Filling the pipe volume itself can be significant depending on the length of the main and number of laterals. If the pressure dosing design for the drainfield requires a larger volume dose, then it may be better to incorporate a separate pump chamber such as the IM-540 tank. The IM-540 tank has a working capacity of 475 gallons is optimal for in-series applications, retrofit applications to increase the volume of an existing septic tank and is Ideally sized for use as a trash-tank or pump tank.