Introduction
Designing, installing, and operating a wastewater collection system in cold regions requires additional consideration to ensure cost-effective, uninterrupted service. The primary concern with wastewater collection in cold climates is freezing. Freezing ground complicates the installation and maintenance of a sewer system, while frozen pipes and components lead to blockages, pipe bursts, and system failures. Cold climates impact the design, installation, and operation of a collection system. Winter-proof your low pressure sewer system with the information in this article.
Pressure Sewer Systems as an Alternative
Pressure sewer systems provide an alternative for applications where gravity sewer systems are less feasible or economical. They help combat difficult terrain such as rocky, hilly, or long flat land. The primary differences between conventional gravity sewer systems and pressure sewer systems are the piping network and the reduction of solids size in wastewater at each residence. Pressure sewer systems use a network of grinder pumps to transport wastewater through small diameter pipes, directly to a sewer main, lift station, or treatment system.
Grinder Pumps and Their Function
A grinder pump is a submersible pump that reduces particulates in a waste stream into a fine slurry using a grinding mechanism and pumps the waste at high pressure. To overcome challenging terrain, installers place pipes just below the frost line and follow the natural landscape. The frost line is the depth at which the ground freezes in the winter, varying based on geographic location. Understanding this factor is critical when planning wastewater management systems. Install pipelines below this line to prevent freezing. Use local climate data, soil composition, and historical weather patterns to determine the depth.
Installation Challenges in Cold Climates
Frozen grounds pose a challenge to the installation of any collection system by increasing the time and effort required to excavate and lay pipe. Traditional gravity systems require sloped pipes to move wastewater, which necessitates extensive excavation and precise grading. Pressure sewer systems, however, require smaller diameter piping and can follow the contour of the land without the need to excavate for deep, sloping, large diameter piping. For a cold climate, this is particularly helpful when dealing with long flat runs of terrain, where gravity systems would require costly lift stations. Also, they are suitable where the ground composition is rocky, making excavation more difficult. Whenever possible, schedule collection system installations during warmer months to avoid challenges such as frozen ground or snow cover.
Importance of Insulation and Winter-Proofing
When designing systems for cold climates, proper insulation is critical to prevent the system from freezing. Apply insulation to the basin, the cover, and all piping in the network. Utilizing pipes made of high-density polyethylene provides additional flexibility and resistance to cracking under freezing temperatures. Proper insulation protects the infrastructure and extends its lifespan. Ensure all joints and connections are properly sealed to prevent water entry, which can freeze and expand, leading to joint failure. Snow coverage also acts as an insulator for underground infrastructure. During long bouts of extreme cold weather with no snow, systems are at a higher risk of freezing.
Above-Ground Options in Permafrost Regions
In regions north of the permafrost line, traditional burial methods may not be feasible due to permanently frozen ground. In these areas, above-ground options offer practical alternatives. Insulate the grinder pump station and all piping conduits to prevent freezing. This solution becomes significantly more cost-effective compared to a gravity system, as it eliminates the need for excavation completely. Equip the basin and pipelines with high-performance insulation to protect the equipment from harsh weather and maintain operational efficiency.
Operational Considerations
Once installed properly, a pressure sewer system has few operational differences from a climate perspective. Conduct regular maintenance checks on all components, particularly before and during the coldest months, to ensure reliability. Remote monitoring allows for real-time data collection on a system, alerting an operator of potential issues before they escalate into significant problems. The longer wastewater is stagnant in a basin, the greater the risk of freezing. Adjust the on-off parameters of each station to encourage frequent, short pump run times, reducing the retention time and risk of frozen sewage.
Emergency Protocols
Finally, prepare emergency protocols and procedures for dealing with freeze-related incidents to allow an operator to act quickly if an incident occurs, minimizing damage or environmental impact.
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The article was first published in Environmental Science & Engineering Magazine February 2025 issue.