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In order to bring your trenchless rehabilitation project in on budget with less risk, it is critical to have the right design– up front – of the bypass segment of the project.
View the on-demand webinar to learn how to build a better bypass.
Here are nine key sewer bypass planning and design components to incorporate into your next trenchless sewer rehabilitation project.
Document Scope
When designing your project, determine whether a sewer bypass is truly necessary to perform the work. Less-costly trenchless technology alternatives can include employing a diversion, accessing parallel sewer lines, or using flow-through plugs.
Determine Bypass Flow
If a sewer bypass is necessary, determine bypass flow requirements in the design phase. This will help reduce price disparity between bypass subcontractor bids and will lessen the chances of paying more for an over-designed system, or conversely, experiencing the environmental impacts of and paying the price for an under-designed flow requirement. If flows are not available, a good rule of thumb is to design the bypass flow plan for the worst-case scenario.
Pinpoint Common Access Issues
Plan for access issues in advance to lessen interruption to the sewer rehabilitation project, as well as to minimize impact to surrounding areas in the community. Access issues to consider include:
Identify Issues That Could Increase Project Duration
Plan a realistic sewer bypass project timeframe by thinking of issues that could affect project duration ahead of time. Common issues that can increase cost and extend impact on the community include unrealistic expectations about mobilization and demobilization time, and delays in achieving necessary access.
Calculate the Correct Bypass System Size
Calculating the correct system size during the planning stage can eliminate common issues that can derail a project, such as undersized pumps and discharge pipe, suction interference, cavitation issues, lack of pump redundancy, and ragging or debris problems. A good rule of thumb is to require bypass vendors to provide system calculations in addition to their bypass plan, and have those calculations reviewed by a qualified engineer.
Plan for Blocking of Flow
Your bypass provider should provide you with details regarding the method that will be used to block live flow, along with other critical flow-blocking plan components, including:
Be sure to check that your provider has the appropriate training and experience to safely set and remove the plugs when required.
Prepare for Contingencies
There are plenty of variables outside your control on any trenchless sewer repair project. To help meet most bypass contingencies, answer these questions during project planning:
Hire the Best-Qualified Pump Supplier
It’s important that you have the best-qualified pump supplier or contractor on the project. To be sure your supplier’s experience matches the needs of the project, consider:
Ensure the Best Value
Bypass is a critical component of the overall sewer rehab project, so it’s important to control costs and maximize value. Know whether you’re working with a term contract or a defined scope. Be sure the bid items are detailed as opposed to being lumped into one line item, and break these items down on term contracts. This helps underscore value and can help reduce costs.
Remember, an increase or decrease in any of the following is relative to the cost of the bypass:
Duration – while longer duration usually equates to more cost, a longer run time can offer the opportunity for adding value to perform necessary repairs or rehab discovered during the project.
Also, consider if it makes sense to increase the rehab footage. Pipe is cheap. Mobilization of the pumps is where most of the bypass cost is derived. If you are already on site, performing extra rehab in the line you are already bypassing will add a tremendous amount of value because it will cost more to go back later to do it.
A sewer bypass can only go two ways – good with no incidents or terribly wrong with negative environmental, financial, brand, and business consequences. Make sure to incorporate good flow control initiatives during the planning process to reduce unknown variables and ensure the success of your next trenchless sewer rehabilitation project.