City officials explore grinder pumps for Newtown project

For the Newtown Water and Sewer Expansion Project, McMinnville officials are considering a switch from using the gravity sewer system to a grinder pump system.

The old system of using gravity requires the large sewer pipe to be on a downhill slope from where it begins until it reaches a tap into the city’s central sewer system. Making sure the line is accurately placed requires a lot of excavation and in some areas that is extremely difficult.

On the other hand, a grinder pump can be placed in problem areas for the gravity system, which includes any hilly, rocky, flat or wet area. It requires a smaller pipe and can be placed just below the surface. Best of all, uphill isn’t a problem. The sewer from this system can travel through elevation changes of over 138 feet until it taps into one of the city’s current sewer lines.

One major difference for property owners is the city would pay for the gravity system, while each household would pay for the grinder pump system. This could mean an extra expense of $5,000 per household or business.

Grinder pump stations incorporate the grinder pump, motor control and level-sensing device integrated into a compact unit, easily removable for service when necessary. The systems are reliable and require very little maintenance, according to its manufacturer.

‘Service calls for this system are usually once every eight to 10 years,’ said Wascon sales and service representative Steve Bennett. ‘They are very reliable. If the unit needs to be replaced, just pull it out, unhook it, hook up a new one and you are back online in less than 30 minutes.’

The system does run on the electricity of the home or business and is a low-energy system. Typical annual energy consumption equals a 40-watt light bulb.

Along with being responsible for the electricity used by the unit, customers would also be required to pay for the unit and its installation. The cost of a grinder pump is $2,000. Installation cost is around $3,000 and that’s per household. Also, there will be a $650 tap fee.

If officials go with the grinder pump system, they must decide who will be responsible for repair and maintenance. A small monthly service charge will be added to the monthly sewer bills if the city accepts responsibility. Customers will be responsible for their own repair and maintenance if the city doesn’t take this on.