Collections 101

What are collection systems and how do they work?

The District has gravity and pressurized collection systems. An explanation of the two types of systems follows:

Gravity Collection Systems –

Conventional gravity collection systems are the most popular method to collect and convey wastewater. Pipes are installed on a slope, allowing wastewater to flow by gravity from a house site to the treatment/reclamation facility. Pipes are sized and designed with straight alignment and uniform slope to maintain self-cleansing flow. Manholes are installed between straight runs of pipe to ensure that stoppages can be readily accessed. District lines are generally eight inches or larger and are typically installed at a minimum depth of three feet and a maximum depth of 25 feet. Manholes are located no more than 400 feet apart or at changes of direction or slope. Customers on conventional gravity systems are charged according to Rate A.

Download Rate schedule A >

Small Diameter Variable Grade Systems (SDVG) – This type of system is a gravity collection system utilizing a septic tank to remove solids from the wastewater, thereby allowing smaller diameter pipes and shallower grades to be used. Flow is transferred to the central collection system by gravity. Customers on SDVG systems that receive full maintenance are charged according to Rate D.

Download Rate schedule D >


Pressurized Collection Systems

Pressurized systems serve subdivisions with larger lots and/or hilly terrain where a gravity collection system is impractical or uneconomical. Pumps located on each property pressurize small diameter lines that feed into existing gravity sewer mains or direct to central treatment/reclamation systems.

Download a list of subdivisions on pressurized collection systems served by the District >

The District System includes two types of pressurized systems:

Septic Tank Effluent Pump Systems (STEP) – A STEP system includes a septic tank, a screen chamber, and a small, high-pressure pump within the tank. Solids settle to the bottom of the septic tank. The liquid waste is pumped through a small pressure line into sewer lines leading to the District wastewater treatment/reclamation plant. The septic tank needs to be cleaned out every three to five years. The life cycle of the pump is typically ten years.

Download a more detailed explanation of STEP Systems >

If you have a STEP system and are paying Rate B or Rate E, the District takes care of cleaning the septic tank and replacing the pump.

Download Rate schedule B >
Download Rate schedule E >

If you have a STEP system and are paying Rate C, the property owner is responsible for operations, maintenance and replacement costs on the pump and septic tank.

Download Rate schedule C >


Grinder Pump Systems – A grinder pump system includes a pump and pump tank and small diameter pipes. Wastewater from the house flows by gravity to a tank buried in the ground that contains a grinder pump. The pump, much like a kitchen garbage disposal, shreds the solids into tiny particles. The mixture of water and waste is then pumped into small diameter pipes and transported under pressure to the wastewater treatment/reclamation plant.

Download a more detailed explanation of Grinder Pump Systems >

If you have a Grinder pump system and are paying Rate F, the District operates and maintains the pump and pump controls.

Download Rate schedule F >

If you have a Grinder System and are paying Rate G, the property owner is responsible for the operations, maintenance and replacement costs of the grinder pump, pump tank and electrical controls.

Download Rate schedule G >


Lift and Pump Stations

The District's collection system includes 20 lift or pump stations. Lift and pump stations are used to move waste to higher elevations. Wastewater is fed into and stored in an underground pit, commonly known as a wet well. The well is equipped with electrical instrumentation to detect the level of wastewater present. When the wastewater level rises to a predetermined point, a pump will be started to lift the wastewater upward through a pressurized pipe system called a sewer force main from where the wastewater is discharged into a gravity pipe.