As a site engineer, you know the challenges of designing a sewer system in tough terrain. Whether you're designing a new community or replacing a failed gravity sewer system, ALL-TERRAIN SEWER® pressure sewer systems from E/One are ideal for any terrain: flat, wet, rocky or hilly.
Pressure Sewer Systems vs Gravity Sewer Systems
Benefits of Pressure Sewer Systems
When communities migrate from septic tanks to central sewer systems, they will likely consider gravity sewer systems first. However, gravity sewers may not be the best choice for the site conditions. "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. This can translate into huge savings in upfront costs, which can make or break a project.
Pressure Sewer vs Gravity Sewer
Replacing a sewer system. Soil conditions can 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.
Designing a master planned community. Gravity sewer systems may also require numerous large, expensive lift stations. Sweetwater Ranch is a master planned community in Kerens, Texas. The limestone environment has a variety of design challenges — impossible to penetrate, and peaks and valleys that result in higher-than-typical head conditions. A gravity sewer system would have required cuts as much as 20 feet deep and 15 lift stations.
Below, Rich Wheeler, P.E. from Malone/Wheeler, Inc. discusses how ALL-TERRAIN SEWER from E/One made an impact. Read more in our Case Studies section.
Pressure Sewer System Design Tools
Visit E/One's Sewer System Design section for sewer system design assistance, free system design software, and a cost comparision tool that can illustrate savings of E/One pressure sewer systems vs gravity, STEP and vacuum sewer systems. Need assistance? Contact E/One for system design guidance.
Sewer System Upgrades: Eliminating Infiltration & Inflow
As communities face aging sewer infrastructure, many are turning to ALL-TERRAIN SEWER pressure sewer systems from E/One for the solution. This video describes how communities can save tens of thousands of dollars on treatment and repair costs alone.
Learn more in our Sewer Renewal brochure.
Case Study: Eliminating Infiltration & Inflow
The gravity sewer system in Honea Path, South Carolina, dates to the early 20th century. More recently, it experienced I&I during rainstorms. Treatment costs were as much as $87,000 per month. Honea Path's experience with ALL-TERRAIN SEWER started with a single E/One grinder pump installed at a problematic location. With great results, the town started implementing pressure sewer, and reducing I&I and treatment 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 applications. Pumps & Systems magazine featured an article about SPD pumps for pressure sewer systems that compares SPD and centrifugal pumps.
E/One offers a range of grinder pump stations for residential (simplex stations) and light commercial (duplex through quadplex stations) applications. All of our stations use the 1 hp Extreme Series pump. Visit the Product Catalog for the available tank capacities, materials and GPD ratings.
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.
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 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.