If the Massachusetts DEP does not accept the Town plan to use Advanced I/As to remove the nitrogen in Oyster Pond, then a low-pressure sewer system will be installed. This is called the Traditional Backup Plan in the Oyster Pond CWMP. It would include 15,400 feet of low-pressure collection sewers around the pond; the effluent would then be conveyed approximately 6,000 feet by low-pressure transmission sewers to the Shiverick’s Pond Lift Station behind Main St. It would be then be transported via the Town’s existing sewer system to be treated and released at the Town’s Blacksmith Shop Road Wastewater Treatment Facility. Initially a total of 189 dwelling units would be required to tie into the sewer system to meet the required TMDL limits. If that does not happen, then three more units for a total of 192 dwelling units would be served by sewer.
A conventional gravity sewer system is not feasible around Oyster Pond due to the steep terrain and nearness to the waterfront. With the low-pressure system, each dwelling or possibly a cluster of buildings will need a pumping system known as a grinder pump. The grinder pump acts like a garbage disposal by grinding a household’s water waste from toilets, washing machines and showers, etc. and pumping it to the sewer collection pipes.
This collection system can represent some of the highest costs of a sewer system, from 50% to 75% of the total capital cost of a system. This is due to the long length of piping needed to connect to each dwelling.
Ownership and maintenance of the grinder pumps can be an issue in this type of system. Who owns, operates and maintains the grinder pumps? They will be located on private property, so an easement is needed to allowed the Town access to the pumps if needed.
As a precedent, in the Little Pond sewer area, the Town purchased grinder pumps with a 5-year warranty and provided them to homeowners. It was the responsibility of the homeowner to pay for installation of the grinder pump. However, the Town did give homeowners a $1800 rebate for the installation costs. The Town will maintain the grinders once the 5-year warranty expires and will replace them at the end of their service, which is typically 15 to 20 years (if there is no evidence of misuse).
When the grinder pumps were picked up for installation, the property owners had to sign an agreement transferring ownership of the pump from the Town to the property owner. This agreement also gave the Town or its agent permission to enter onto the property to service the pump.
Homeowners should be aware that having your home hooked up to a sewer system with a grinder pump does not mean that you can forget about it as is the case with a traditional sewer system. For one thing, the pumps will not work during a power outage. Once the storage capacity of the pump is full (from 38-46 gallons), sewerage can begin to back up into the building. The pump system also must be winterized if the house is empty over the winter. Homeowners also must realize that the grinders cannot accept certain objects such as diapers, sanitary items or hazardous materials. (Normal septics can’t either!)