Construction is challenging, and each season of the year comes with inherent issues that building teams must solve. Primarily related to weather, project crews must be able to adjust their plans according to the conditions they encounter. In many parts of the Pacific Northwest, extensive rainfall from October through April is normal, with Portland receiving an average of 36” of precipitation per year. Recently, in fact, Portland had nearly an inch of rain in only two days’ time.
Wet conditions pose a variety of challenges for jobsites, which differ based on ground-up sites, urban vs. rural sites and the type of construction that is underway. Our teams heavily consider the time of year and the risks involved when scheduling work to consider likely weather conditions.
For instance, ground-up construction sitework is not advised to begin during the wettest weather months without special preparation. When discussing project schedules, it’s worth considering whether shifting the start date or spending dollars on wet weather preparations will provide the best benefit to the owner.
In addition to start dates, good contractors are wise to build in weather delays into the overall project schedule to hedge against costly delays. Many work items cannot be completed in wet conditions. If there is no flexibility in the schedule to accommodate for wet weather delays, completion dates may be missed.
Weather Sensitive Trades
Several construction trades are affected by weather, such as:
- Concrete Finishing
There are ways to complete this work during wet weather if temporary measures like tents can be erected or other means determined. This is often not feasible for items like full parking lot paving, large concrete slab pours, or complete building roofing operations.
Some strategies to mitigate these risks include:
- Changing project start dates to avoid likely wet weather conditions
- Watching forecasts for potential dry windows and accelerating or delaying work scopes accordingly
- Completing work in double shifts or with multiple crews to take advantage of dry weather windows.
Construction teams must sometimes get creative to find solutions when work must be completed during wet weather. If the answer can’t be ‘wait for a dry day’, temporary protection measures will have to be constructed and maintained for the duration of the work.
Site Excavation Challenges
Wet weather conditions pose a number of challenges for greenfield construction sites, including standing water, unstable ground surfaces, and more. When the ground is saturated, it makes any work with heavy equipment challenging, if not impossible. Saturated ground makes it difficult to operate excavating equipment. These machines can sink, become stuck, or just generally make a mess of the ground while trying to complete their work. Additionally, muddy surfaces become a safety hazard that can lead to equipment failure. For instance, cranes or large equipment that have stability jacks rely on the surrounding ground for stabilization. If that surface is no longer stable due to the wet conditions, dangerous conditions can arise.
There are some solutions to wet weather excavation work if an owner is willing to pay the increased cost to properly prepare. Some options include:
- Shifting the start date to complete site work prior to the wet weather season
- Placing large rock haul roads and all rock prep under parking lots and building pads prior to the wet weather season.
- Prepping the site with cement treated soil: a soil-cement that is mixed into the native soil that hardens in place.
If construction of a large site cannot be completed during dry weather windows, we highly encourage cement treatment so that a stable surface is in place for construction.
Erosion Control and Stormwater Management
In the Pacific Northwest, erosion control and stormwater management are large topics to consider for wet weather construction. Both are highly regulated, depending on the rules and regulations of the local jurisdiction and The Department of Environmental Quality (DEQ).
Jobsites must be prepared to manage all water that lands on their jobsite with proper dewatering and management techniques. Water often must be filtered and/or treated before it can leave the site by natural means or through the local stormwater or sewer systems.
The State of Oregon and Washington require Certified Erosion and Sediment Control Lead (CESCLE) certification inspectors be present on each jobsite. These individuals or groups are responsible for inspecting and sampling stormwater on construction sites. These individuals must complete a CESCLE certification course and maintain testing logs onsite. A failure to do so can lead to significant fines.
Safety in Wet Weather
Wet weather comes with a multitude of site safety challenges for crew members. These include:
- Increased risk of slips, trips and falls due to muddy or wet surfaces.
- Decreased visibility if safety glasses are wet, or the environment is dark, foggy or saturated with rain. These conditions also add to the increased risk of slips, trips and falls.
- Windshields or mirrors can become fogged or clogged with debris, making operating them safely an added concern. It’s critical that workers stop their actions to clean or clear windows and mirrors before proceeding with their work.
- Clogging tools, such as saws becoming clogged with wet sawdust, etc. This can lead to safety concerns as well as equipment failure, accidents/injuries or decreased production.
- Excessive weight of materials due to ponding water or saturation. This can lead to strains or other injuries of workers.
- Employee visibility – wet and foggy conditions can lead to poor visibility for employees operating machinery, heavy equipment, or passenger vehicles. A Class II high visibility garment is recommended for all workers.
- Slippery tools or materials – working from heights with wet, slippery tools or materials increases the likelihood of these hazards striking workers below. Utilizing the correct glove type and establishing a drop zone is an important consideration.
- Electrical hazards – Power tools, including temporary power distribution boxes and extension cords, have the potential for electrical shock when operated when wet.
In addition to these safety concerns, crew members working in wet conditions without proper protective equipment and waterproof gear are at risk of hypothermia. A serious health condition, according to the Mayo Clinic, signs of hypothermia can include:
- Slurred speech or mumbling
- Slow, shallow breathing
- Weak pulse
- Clumsiness or lack of coordination
- Drowsiness or very low energy
- Confusion or memory loss
- Loss of consciousness
This condition is a medical emergency and should be treated as such. Crew members must be equipped with proper PPE and be provided with breaks from the weather at regular intervals.
With proper planning, contractors can avoid the pitfalls and dangers that wet weather presents. Discussions should take place well in advance of work beginning so that the site can be properly prepped, materials ordered and crew members equipped with proper equipment. As is always the case, prevention is the best recipe to keep jobsites safe and on schedule.
If you’re considering a project that must take place during wet weather conditions, we’d encourage you to contact our teams now to discuss your options.