A Primer on Effective Sewer System Design

Creating an efficient and well-designed sewer system might not be the flashiest project you take on, but it is one of the most impactful. Unfortunately, because of the price tag, many communities put off sewer projects until they start to have problems.

When problems do occur, they can incur heavy expenses and inconvenience your community. A failed sewer system can also lead to environmental problems, fines, and health hazards.

It’s important to continuously monitor the health of your sewer system to determine the right time to make upgrades or replacements to aging infrastructure. You should always work with an expert engineering team that can guide you in creating a well-functioning and cost-effective sewer system.

There are multiple different types of sewer systems that you can design and install depending on the need. Storm sewers are made to handle rainwater runoff and snowmelt, while sanitary sewer systems transport wastewater from residential and commercial buildings to be treated.

In the past, there have been combined sewer systems that do both, though they are no longer allowed in Michigan. Some still exist, but the goal for new sewer projects should be to separate them.

Standards and Guidelines for Sewer Design

Designing a sewer system requires understanding a web of complex rules, regulations, and guidelines—along with the unique qualities of your own community. The best place to start is by reviewing your state’s regulations on sewer system design and installation, including the latest environmental regulations. You’ll also want to have extensive conversations with your department of public works, elected officials, financial advisors, and other community leaders and stakeholders.

Dimensions

One of the first things you will need to determine in the sewer system design process is the size of the system. Finding the answer will require an in-depth study of the current homes and businesses—while also allowing for growth over the next several decades. You’ll need to look at the capacity and load of your current system and how you expect it to change with the addition of new homes or businesses.

This can be challenging, especially in communities with large business or industrial districts, because the amount of water they use can vary widely. One of the biggest challenges communities face is accurately predicting the capacity their sewer system needs to have.

That doesn’t always mean that your new sewer system needs to be built for the capacity that you’ll need in 50 years, but creating room for expansion is a good way to make sure you’re setting the future of your community up for success.

Location

There are a lot of environmental and civic regulations on the location of your sewer system that you’ll need to sift through when you make the design. Many regulations require sewer lines to be placed a set distance for the water mains, and that they run parallel to property lines.

Keep in mind that you’ll also need to take special consideration if your sewer system needs to cross a river, cross a flat area, or run in the opposite direction to the slope. And if you’re designing a sewer system in a northern state such as Michigan, you’ll need to bury the lines deep enough that they won’t be affected by a deep freeze during the winter.

You’ll also need to locate other private and public utilities to avoid conflicts and ensure the design can be constructed.

Materials

When looking at the materials to use for your new sewer construction project, there are several options to choose from, including concrete, PVC, clay, and iron. The right choice will depend on the location of your project, the type of soil the pipes will be buried in, and the budget of the project. Some materials are more durable than others and will likely last longer, though those tend to be more expensive.

Lifespan

The lifespan of most sewer systems built today is around 50 years, though that can change depending on several factors. A well-designed sewer system with the right materials is likely to last longer than one where corners have been cut. The lifespan can also depend on the climate and soil where the sewer system is located, and whether the pipes were buried at the proper depth. Plus, if your sewer system gets a lot of heavy use from new homes, apartments, or major businesses, it will likely require more maintenance and replacement work—so be sure to set your sewer rates accordingly.

Fleis & VandenBrink’s Sewer System Design Services

The team at Fleis & VandenBrink has worked on countless sewer system projects since our founding in 1993. We’ve designed major sewer systems for large communities, assisted with minor upgrades in rural areas, overseen construction on commercial projects—and everything in between.

We work with communities to perform feasibility studies, calculate the flow that will be generated by the size of the community, and document other factors that will impact your design. Our engineering team can also help you determine the cost of a new sewer project, and identify potential sources of funding, such as grants and low-interest loans.