Three Ways to Avoid Construction Risks on Diversions and Fish Screens
By Molly Davidson, PE – Capital improvements on irrigation systems are a huge undertaking—none more so when it comes to instream diversions and fish screens. Planning, design, and permitting of these large projects are critical; but the true test of the project’s success will almost always come during construction. Fortunately, there are several ways to avoid risks during construction on these projects.
Even the best projects or designs can be undone by challenges arising from schedule delays, lack of planning for flood events, or inadequate quality assurance testing. With thoughtful structuring of bidding and construction documents, the odds for success increase significantly.
Both the construction and engineering professions have long used the following three tactics to help projects result in favorable outcomes for everyone.
1. Schedule Incentives for Early Completion
While liquidated damages are commonplace in construction contracts, monetary incentives are far less common. In many cases, it makes sense to incentivize contractors to complete portions—or all—of the work as soon as possible. Specifically, for diversion and fish screen projects, additional time between construction completion and system operation is key.
One way to provide an incentive to accelerate completion is to bracket monetary bonuses based on substantial completion ahead of the contract dates. For example:
|Calendar Days Prior|
to Substantial Completion
This approach requires a detailed definition of several criteria including:
- original substantial or final completion date
- acceptance of completion verification
- bonus distribution
2. Include a Flood Event Bid Item
Even with incentives to complete construction as timely as possible, high water and flood events—instigated by any number of sources—can occur anytime during the project. Diversion and fish screen projects nearly always include a significant portion of the work instream. This work presents risk to owners and contractors alike.
Since most irrigation systems require projects to occur in the winter when water is not being diverted, ice jams and flash snowmelt floods are an increased and unpredictable risk. A useful way to plan for this risk is to include a bid item up front to identify the effort needed to address a defined flood event. We have used this approach with success on many projects.
Some key items to keep in mind when developing a flood event bid item:
- Define a specific flowrate and/or water surface elevation to trigger the event. Consider adding an item in the bid that states floods that do not impact the work are not included.
- Define a clear way to measure the trigger criteria and identify the responsible party.
- Define how the event ends. Will it be per-day or per-occurrence? Is there a limit to the number of events over a period?
- Describe the minimum typical actions a contractor must take to dewater the site. Include a detailed temporary diversion plan.
- Describe the actions the flood event bid item is meant to cover such as increased dewatering, cleanup of affected area, repair and/or retesting of impacted work, and revisions to the diversion system to prevent addition flood events.
With the flood event bid item included up front, contractors can place the cost of this risk into a separate item that only gets used if necessary. Otherwise, this cost may get rolled into the work itself, which becomes hard to distinguish. This practice gives the owner a clearer picture of what to budget for and how much to set aside for contingency.
3. Incorporate Acceptance Testing to Measure Success
Some construction projects like sewer collection systems have very clear and common-sense testing requirements to meet before the owner accepts the completed work. Irrigation systems, especially diversions and fish screens, can benefit from similar requirements. This can also provide clarity for the contractor from the start, so they know exactly what to expect.
Tests can vary widely depending on the size, type, and complexity of the project. Some examples are a light test on buried pipelines, leak tests on gates, and those that measure the minimum time of smooth and unaltered operation of a screen cleaner, just to name a few.
When tests—including the criteria that determine a “pass” or “fail”—are clearly defined, both the owner and contractor alleviate the pressure of a potential subjective decision and conflict. The void of a clear acceptance test can result in the contractor claiming the work is built per plan, while the owner views the operation of the work as insufficient, resulting in conflict over completion and payment.
Incorporating Lessons Learned
None of these three approaches are new, but they can be absent from irrigation capital improvements projects. Irrigation owners can also put these tools to use with great success, especially on larger projects.
It makes sense to consider implementing these tactics to increase success, avoid risk, and define acceptable work. By learning from lessons in the industry at large, irrigation owners and contractors both can enter and exit projects with success.
Matt Barnes, PE, CFM is a professional engineer and certified floodplain manager who works in Morrison-Maierle’s Helena office. A native Montanan, he enjoys being in the outdoors with his family when not working in the outdoors as a specialist in natural resources engineering.
Molly Davidson, PE is a water resources engineer with experience in planning and design of irrigation, storm drainage, and water resource projects who works in Morrison-Maierle’s Missoula office. When not at work, she enjoys spending time with her family in the outdoors working on her farm.