Operation and Maintenance or Pressure Sewers
Routine operation and maintenance requirements for both septic tank effluent pump and grinder pump systems are minimal. Most system maintenance activities involve responding to homeowner service calls usually for electrical control problems or pump blockages. Septic tank effluent pump systems also require pumping every two to three years.
The inherent septic nature of wastewater in pressure sewers requires that system personnel take appropriate safety precautions when performing maintenance to minimize exposure to toxic gases, such as hydrogen sulfide, which may be present in the sewer lines, pump vaults, or septic tanks. Odor problems may develop in pressure sewer systems because of improper house venting. The addition of strong oxidizing agents, such as chlorine or hydrogen peroxide, may be necessary to control odor where venting is not the cause of the problem.
Generally, it is in the best interest of the municipality and the homeowners to have the municipality or sewer utility be responsible for maintaining all system components. General easement agreements are needed to permit access to on-site components, such as septic tanks, septic tank effluent pump units, or grinder pump units on private property.
Pressure sewers are generally more cost-effective than conventional gravity sewers in rural areas because capital costs for pressure sewers are generally lower than for gravity sewers. While capital cost savings of 90 percent have been achieved, no universal statement of savings is possible because each site and system is unique.
Average Installed Unit Costs for Pressure Sewer Mains and Appurtenances (2011) – Link to Information: Average Installed Unit Costs for Pressure Sewer Mains
Purchasing pumping stations in volume may reduce costs by up to 50 percent. The linear cost of mains can vary by a factor of two to three, depending on the type of trenching equipment and local costs of high-quality backfill and pipe. The local geology and utility systems will impact the installation cost of either system.
The homeowner is responsible for energy costs, which will vary from $2.00 to $5.00/month for grinder pump systems, depending on the horsepower of the unit. Septic tank effluent pump units generally cost less than $2.00/month.
Preventive maintenance should be performed annually for each unit, with monthly maintenance of other mechanical components. Septic tank effluent pump systems require periodic pumping of septic tanks. Total O&M costs average $200-500 per year per unit, and include costs for troubleshooting, inspection of new installations, and responding to problems. Mean time between service calls data vary greatly, but values of 4 to 10 years for both grinder pump and septic tank effluent pump units are reasonable estimates for quality installations.