Careful planning, installation and monitoring will reduce the risks of spills and leakages.
Clearing, repairing or replacing a pipe usually requires a temporary sewer bypass to divert the discharge from point A to point B and create a work area.
Every sewer bypass project has potential pitfalls. If you’re designing, installing and operating the bypass yourself, follow these tips for a greater chance of success.
Managing Risk for People and the Environment
Worker safety and environmental safety should remain top of mind with any bypass operation.
- Follow confined space protocols. Anyone working in a confined space such as a sewer should be properly trained, equipped and supervised.
- Encourage hepatitis A and B shots. During sewer bypass setups and teardowns, workers may be exposed to raw influent wastewater that can carry blood borne pathogens.
- Use a spill containment berm. Placed under equipment, it can capture fuel, oil or wastewater.
Determine the maximum anticipated flow and design the bypass system accordingly.
- Create a professional drawing. Visit the jobsite to understand the needs and constraints, then create a professional drawing that shows what the system will look like. Ask your fluid solutions provider for assistance if you need it.
- Check total friction. To ensure optimal performance of the temporary bypass, check for total friction loss due to restrictions as well as the total length, height, and diameter. If assistance is needed, contact your local FS provider.
- Check the suction lift. The total dynamic suction lift should be no greater than 8.5 metre. The recommended minimum suction depth is 2 metre. A suction lift that’s too high or too low can cause performance loss or equipment damage.
- Control velocity. Generally, you don’t want to exceed 3.5 metre per second.
- Select the right pumps and hoses. There are many different pump options to consider, such as electric, diesel-driven, and hydraulic. Determine your needs and select the appropriate pump for your project.
- Build in redundancy and easy access. Be prepared with backup pumps, and set up your system so it’s easy to swap them in and out. Create good access points for fuelling, maintenance and isolation gate valves.
Keeping Sewer Bypass Operations on Track
Take these steps to help ensure your bypass system operates properly.
- Set up monitoring. An experienced, capable worker should be watching the system. Alternatively, save labour costs by using telemetry to monitor pumps. A telemetry system can automatically send alerts for problems involving fuel level, oil pressure, coolant temperature, flow rate, suction and discharge pressure and more.
- Install discharge line gate flush –& Drain-point to bring in water for flushing. This can help you contend with blockages and other unforeseen issues. Place the gate flush –& Drain-point at the low points where water will collect.
Testing and Inspection before Start-Up
Fixing issues becomes much more complex once a system goes live. Reduce the risk of problems with these steps.
- Check all pump lubricant and fuel levels. Don’t let your bypass fail due to a lack of basic pump maintenance.
- Use gauges to check the priming, suction and discharge systems. Outfit the suction system with a vacuum gauge on the priming and suction side and a pressure gauge on the discharge side for continuous monitoring.
- Check the telemetry system if you’re using one. Make sure it’s connected and that all sensors are sending signals.
- Test the bypass system. Fill the bypass with fresh water to test for leaks.
- Attach your emergency response plan/contact list to every pump. Keep it updated and use a daily checklist.
Maximizing Safety and Efficiency during Teardown and Removal
When the job is finished and it’s time to tear down the temporary bypass, do it right.
- Remove the sewer valve at the lowest flow times. This is generally between 11 p.m. and 4 a.m.
- Keep the equipment in ready position. If the owner’s system isn’t ready to accept the flow, you may need to restart the pumps to avoid serious spills.
- Sanitize and disassemble the system. When the owner’s system is back up, make sure that all equipment is properly sanitized and disinfected with clean water.
Planning and execution of a temporary sewer bypass can be a large and costly undertaking and you should always consult with an expert regarding the specific circumstances, applicable rules and regulations related to your site and to your situation.
Read also “Tips for Successfully Starting a Sewer Bypass”