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Water can complicate even a well-planned construction project.
For contractors working around streams, rivers, shorelines, or other bodies of water, managing that water is often one of the first challenges to address before the primary work can begin. Crews may need to isolate an area, redirect water around it, remove water from the work zone, and maintain access for workers and equipment — all while accounting for changing site conditions.
That is why crews should consider temporary water control early in project planning rather than treating it as a problem to solve once they arrive on site.
From diversion and dewatering to construction sequencing and site access, developing a clear water-control strategy can help create a more manageable work environment and keep the different phases of a project working together.
Start With the Water, Not the Work Area
Before deciding how to keep a construction area dry, start by understanding the water itself.
Where is it coming from? Where does it naturally flow? How could rainfall change those conditions? And, perhaps most importantly, where will that water go once the work area is isolated?
These questions can influence the temporary water-control system as well as equipment placement, excavation, staging and construction sequencing.
For excavation work, water control can also be a safety issue. OSHA’s excavation requirements state that employees generally may not work in excavations containing accumulated or accumulating water unless adequate precautions are in place. When excavation interrupts natural surface drainage, OSHA requires diversion ditches, dikes or other suitable means to prevent surface water from entering the excavation and to provide adequate drainage around it.
The specific water-control approach depends on the project, but understanding site conditions before mobilization gives contractors a better foundation for determining what they need.
Diversion vs. Dewatering: What’s the Difference?
Although the terms are sometimes used interchangeably, water diversion and dewatering serve different purposes.
Diversion controls the path of water and keeps it away from the active construction area. Dewatering involves removing water from an area where work needs to occur.
Temporary cofferdams can help accomplish that first step by separating the work zone from the surrounding water. Depending on the project, water can then be diverted around the isolated area and the remaining water removed so construction can proceed.
This is a recognized approach to in-water construction. U.S. Army Corps of Engineers guidance describes temporary cofferdams and other diversion structures as methods of isolating construction from streamflow. Corps engineering guidance also notes that cofferdams facilitate site dewatering when construction requires a dry work area near or across streams.
That distinction is important during planning. Instead of asking only, “How are we going to pump this water out?” contractors should first ask, “How are we going to keep additional water from entering?”
Create the Right-Sized Dry Work Area
Temporary water control doesn’t necessarily mean drying an entire body of water or an unnecessarily large section of the project site.
The goal is to establish an appropriate isolated work area for the task being completed.
Once crews isolate the necessary area, they can address the water remaining inside it according to the project’s engineered water-control and dewatering plan.
Consider the space required before positioning the temporary barrier. Construction documents from the U.S. Army Corps of Engineers have specified that temporary cofferdams provide adequate clearance for work within a dewatered area, including space for pumps and installation and removal operations.
That reinforces a practical lesson: Don’t design the dry area around the barrier alone. Design it around the work that has to happen inside the barrier.
Make Construction Sequencing Part of the Plan
Temporary water control and construction sequencing should work together.
Depending on the site, contractors may isolate one section, complete the necessary work, restore that area, and then move to another section. Other projects may require upstream and downstream isolation while diverting water around the construction zone.
A basic sequence could include:
Isolate → divert → dewater → perform the work → inspect → restore → remove the temporary system.
That isn’t a universal construction sequence. The actual process must reflect the site’s engineering, permits, environmental requirements, and conditions.
However, planning the sequence before mobilization can reveal potential conflicts early.
For instance, where will the excavator operate after the barrier is installed? Will a pump or discharge line interfere with equipment movement? Can materials reach the work area? Does one portion of the project have to be completed before the temporary water-control system can be moved?
Answering those questions on paper is generally easier than solving them once equipment and crews are already on site.
Don’t Forget About Site Access
A dry work area still needs to be workable.
Contractors should consider how personnel, equipment and materials will move through the site during every stage of the project. Temporary barriers, pumps, hoses and other equipment can consume valuable working space, particularly at constrained sites.
OSHA’s excavation standard also contains specific access and egress requirements for excavation work. For trench excavations 4 feet or deeper, a stairway, ladder, ramp or other safe means of egress must be positioned so employees do not have to travel more than 25 feet laterally. A competent person qualified in structural design must design structural ramps used for equipment access or egress.
Those requirements illustrate why access shouldn’t be an afterthought.
Coordinate the water-control layout with the larger site plan so the solution used to control water does not unnecessarily interfere with the work it was installed to facilitate.
Prepare for Conditions to Change
The conditions present when a temporary water-control system is installed may not be the conditions crews face several days later.
Rain can increase runoff. Water elevations and flow conditions can change. Excavation can reveal unexpected groundwater or seepage. Construction activities themselves can alter conditions around the work area.
Monitoring therefore remains important throughout the project.
OSHA requires a competent person to monitor water-removal equipment and operations used to control accumulating water in excavations. Its standards also require competent-person inspections of excavations before work begins and as needed throughout a shift, as well as after rainstorms or other events that increase hazards.
For project teams, changing conditions are another reason to establish responsibilities and contingency procedures before construction begins rather than waiting until water becomes a problem.
Where Aqua-Barrier® Fits Into Temporary Water Control
Temporary cofferdams are one option for isolating an in-water construction area. The appropriate system depends on factors such as site conditions, project requirements, water conditions, available working space, and engineered design.
Aqua-Barrier® is a temporary water-control solution for projects that require an isolated work area.
The larger point is that a temporary cofferdam shouldn’t be considered independently from the rest of the construction plan. Its location affects the size of the dry work area, how water will be diverted, where dewatering equipment can operate, and how workers and construction equipment will access the site.
For that reason, contractors considering Aqua-Barrier should evaluate the system as one part of the project’s overall water-management strategy.
A Practical Water-Control Planning Checklist
Before construction begins, contractors and project teams should have clear answers to several questions:
- What are the anticipated water conditions? Consider normal conditions and reasonably anticipated changes during construction.
- What portion of the site actually needs to be isolated? Define the working footprint before laying out the temporary water-control system.
- Where will the water go? Determine how flow will be diverted around or away from the work zone.
- How will the isolated area be dewatered? Account for the equipment and working space the dewatering operation will require.
- How will crews and equipment access the work? Coordinate temporary water control with excavation, staging and equipment movement.
- What is the construction sequence? Determine when isolation, diversion, dewatering, construction, restoration and removal will occur.
- What happens when conditions change? Plan for monitoring and appropriate responses to rainfall, runoff and other changing conditions.
- What permits and environmental requirements apply? Requirements vary by location and project, so identify them before work begins.
Plan Temporary Water Control as Part of the Project
Successful temporary water control isn’t simply about putting a barrier between water and a construction site.
It requires thinking through diversion, dewatering, sequencing, and access as interconnected parts of the construction process.
A temporary cofferdam can help establish the isolated work area crews need, but its effectiveness depends on how well it fits into the larger project plan.
By addressing water management early, contractors can better coordinate their work area, equipment and construction sequence — and be better prepared for the changing conditions that come with working around water.
For projects considering a water-filled temporary cofferdam, the Aqua-Barrier team can help contractors evaluate project conditions and determine whether the system fits the planned application.