Energy costs of gravity vs. vacuum sewers

Key West Resort Utilities Corp.'s gravity lift station layout.

Lift stations with fewer than 100 equivalent residential connections (ERCs) pay less than $1,000/year for electricity; medium-size stations (LS-2A and ForceMain) pay the most at $6,000 to $8,000/year. Thus, three-year energy costs range from $3,000 to $24,000. Minor variability in energy consumption suggests there’s little inflow and infiltration (I/I) throughout the system.

Average annual sewage pump cost: $2,000; vacuum pump: $10,000 to $14,000. The station’s electricity bills are thus $12,000 to $16,000 per year for a three-year total of $36,000 to $48,000.

Per-lift-station annual electricity costs for a similar number of ERCs are $21/year/ERC for the gravity sewer system and $11/year/ERC for the vacuum sewer system.

One of the larger gravity lift stations serving the golf course area.

Vacuum pumps inside the vacuum station. Seage pumps are located inside the collection tank, which is buried outside the pump station.

Typical residential area served by the Key West Resort Utilities Corp. in Stock Island, Fla., characterized by flat terrain and a mix of single- and multifamily homes.

Close X