Gravity Sewer System: Is This Sewage System Worth Using?

Waste has been following gravity since long before the apple fell. However, as people spread to lower elevations, gravity typically cannot do this alone, needing lift stations.

A gravity sewer system has been providing home owners with a clean solution to dispose of their waste water, and any town would have this system in operation and maintained.

Not all waste now moves downward, though. Although the law of gravity hasn't changed, technology, particularly low-pressure sewer lines, has made it possible for sewage to move.

Grinder pump stations accomplish this by grinding solids into a slurry that can be piped regardless of groundwater depth or slope.

Read on to learn everything about the gravity sewer, how it works, its benefits, and if there are alternatives that your city can adapt.

What Are Gravity Sewer Systems?

Gravity sewer systems transport wastewater from your home, business, or source to a nearby common wastewater pump station using only gravity through manholes and laterals.

The wastewater is pumped to a regional wastewater treatment facility, where it is treated and recycled for landscape irrigation.

The traditional sewer system has numerous branches. A town sewer network is typically separated into major, secondary, and tertiary networks.

What Is the Main Function of Gravity Sewer Systems?

Gravity sewers are sized so that the product does not fill the pipe to avoid airlocks in the system. In case the pipe is filled, it will be expensive to fix.

Installing it, including the number of materials like a pipe, manholes, and laterals, costs between $50 and $60 per foot.

The product flow through the pipes may expand beyond design, causing issues as the pipes age and water infiltration occurs through fractures.

Because no pumps, accompanying filters, or blades break up and remove materials, these sewers are also susceptible to clogs.

To prevent the pipe from going too deep over longer distances, the sewer network needs to lift stations installed to continue their operation and provide more distance to treatment.

How Do Gravity Sewers Work?

Sanitary waste generated on your homeowner property or business will be fed to the sewer pipes of your town, which are situated next to your property in a sewer pump.

No pumps or pressure parts are installed in the system, so the product moves through the system under gravity.

Even though pressure sewer systems are increasingly popular, most sewage and storm water sewer systems were initially established as gravity sewers upon construction.

With a sewer connection, wastewater is moved from your property to the sewer system of your town by gravity via a downward-sloping pipe installation.

They include excavating large, downward-sloping trenches, which in many cases works well when traveling downhill but presents difficulties when the terrain is uncooperative.

The dollars for installing increase as you go deeper. To maintain the movement, you must also sporadically boost and transport wastewater along the path via a lift station.

The difficulty increases if the inflow is going uphill. Digging through hard or sandy soil and traveling great distances likewise have a greater cost.

Gravity Sewer Systems vs. Pressure Sewer Systems

Pressure sewer pipes, also known as force mains, are necessary for systems where gravity cannot move the inflow water from source point A to required point B.

In most cases, the pressure sewer system defies normal movement using submersible grinder pumps to grind sewage into a grease slurry and transport it through the system.

It uses a smaller diameter pipe that does not cost as much and is easier to install. They follow the terrain, requiring a depth below the frost line, and are less susceptible to leaks.

Pressure sewer systems also are less invasive and less costly to install. Maintenance is minimal, with electricity to power the pump the primary cost.

With a grinder pump station, the cutters must be maintained for five to ten years from wear. Problems can also arise as providing a place to build is needed and required.

The installation cost is noticeably lower when comparing a pressure sewer system to conventional gravity systems.

Developers must install water, sewer, and other amenities before building new homes. It has a significant capital cost and a protracted payback period.

Why Should You Get a Pressure Sewer System

Money is time. Cash flow is particularly constrained when the build-out rate is modest. A pressurized sewer system helps you financially in this situation.

A pressure sewer system is far less costly upfront than a conventional one, resulting in real cost savings.

This lowers the cash outlay, with the grinder pump station's construction and cost being postponed until closing.

In addition to being less expensive to install, pressure sewer systems save money over time as lots are bigger and more numerous.

It performs effectively and requires little maintenance for years because it is built to last.

What Are the Advantages of Gravity Sewers?

Since they have operated for so long, these sewer systems have established construction and maintenance processes.

The performance of conventional gravity systems is consistent when they are built and configured properly.

The following benefits are offered by traditional systems that are properly designed and built:

• Can handle water, grease, grit, and solids in sanitary sewage.
• It can provide a steady speed, reducing the production of hydrogen sulfide. In turn, this lessens smells, obstructions, pipe corrosion, and the risk of an explosion.
• Less upkeep than streamlined and solids-free sewers
• It is possible to control stormwater and greywater simultaneously

What Are the Disadvantages of Gravity Sewers?

While these sewer systems have their fair share of pros and advantages, they also have a good amount of risk and cons.

When using these systems, take note of the following:

• Deep excavations may be needed in flat or hilly terrain for installation due to the slope requirements to maintain flow, which raises the cost of construction.
• The slope requirements for typical gravity sewers may need sewage pumping or lift stations because they lead to a system terminus at the tail of the sewer.
• Pumping and lift stations significantly raise the price of the collection system.
• Manholes connected to gravity sewers are a source of infiltration, which increases the amount of water that must be transported, which, in turn, raises expenditures.
• The extension is challenging and expensive as a community develops and changes.
• Professional design, construction, and maintenance are necessary.
• Leaks are challenging to find and present a risk of groundwater intrusion and wastewater exfiltration.

Conclusion

If well-constructed and maintained, conventional gravity sewers are a safe and hygienic means of transporting wastewater. This technology is required for good hygiene and comfort.

However, the treatment will ultimately determine the effects on human health and the environment because the waste is transported to a location for processing.

One must make these considerations when deciding to change to a gravity sewer system.