Pressure Sewer Systems vs Gravity Sewer Systems
Benefits of Pressure Sewer Systems
As communities migrate from septic tanks to central sewer systems, they will consider pressure sewer and gravity sewer systems. "The Secret Life of Pressure Sewers" details the benefits of pressure sewer systems - for one, they use small, 2- to 4-inch force mains that follow the contour of the land and are installed just below the frost line, eliminating the need for large, deep trenches.
Pressure Sewer vs Gravity Sewer
Soil conditions can also make pressure sewer a better choice than gravity sewer. Elwood, Missouri, has soft, loamy soil conditions and relatively flat land. The gravity sewer system was prone to infiltration - lift stations ran constantly to pump out groundwater, and collapsed mains and roadways were common. When the town was washed out by the Flood of 1993, Elwood rebuilt the sewer system using pressure sewer and E/One grinder pumps. Infiltration problems were eliminated, saving thousands of dollars in maintenance costs.
Gravity sewer systems may also require large, expensive lift stations. Great Sky in Canton, Georgia, is a new residential development. A gravity sewer system would have required 20 lift stations because of the steep, hilly terrain. A pressure sewer system cut the number of required lift stations to three.
Sewer System Upgrades: Eliminating Infiltration & Inflow
New video! View our new video, E/One Infiltration & Inflow Solutions. As communities face aging sewer infrastructure, many are turning to E/One pressure sewer systems for the solution. This video describes how communities can save tens of thousands of dollars on treatment and repair costs.
Grinder Pump Selection
Constant, predictable pump output is the foundation for proper hydraulic design. It enables the engineer to minimize retention time, pump wear and deep scouring action at effective levels. E/One's semi-positive displacement (SPD) grinder pump was developed for wastewater application. Pumps & Systems magazine recently featured an article about SPD pumps for pressure sewer systems.
Why Choose E/One Grinder Pumps?
- Designed specifically for wastewater applications
- Pressure sewers are ideal for every terrain and building environment
- Cost-effective for new construction or retrofits
- Engineering and technical support during design, construction, installation and operation
- Reliable performance and no preventive maintenance mean reduced O&M costs
- Free sewer system design assistance and software. Visit our Design Center to learn more.
Sewer System Design
Visit E/One's Sewer System Design section for more information. E/One offers sewer system design assistance and software. Visit our Design Center to learn more.
Frequently Asked Questions
Q: What is the difference between E/One's grinder pump and centrifugal pumps? Why is an SPD pump important in a pressure sewer system?
A: E/One's grinder pump lends itself to complex system designs because of its nearly vertical pump curve (view E/One's curve here) and the resulting nearly identical flow rate allows a wide variety of discharge heads. The predictable flows of the SPD pumps provide tolerance of widely varying system pressures.
The use of SPD grinder pumps is crucial to the success of a pressure sewer system. The performance characteristics of SPD pumps assist in maintaining a sewer network free from blockages. When deposition of solids occurs, tending to block the pipe, centrifugal pumps will move toward shut off, reducing flow and velocity and increasing the tendency to block the pipe. SPD pumps constantly scour the lines to prevent buildup because flow is maintained although pressure or head increased, effectively scouring the pipe.
Q:How is growth in the community handled?
A: Typically, pressure sewer systems are designed for future growth. When designed properly, additional zones can be added as the community grows. New developments will require analysis as they would if a gravity system was used. Existing communities can manage growth simply by adjusting the diameter of the street mains to meet only current or projected future needs.