Proper drainage is an important part of every community. When drainage systems are not working properly, this can result in flooding which can lead to a number of other problems and can be very costly. According David Chesky, Executive Vice President of the Civil Engineering Division of Falcon Engineering with headquarters in Warren New Jersey, “poor drainage will lead to flooding, and if your retention ponds or detention basins aren’t maintained, it can also lead to flooding.”
In his experience, Chesky said that many instances related to poor drainage are a result of a lack of maintenance on stormwater systems where catch basins and pipes either failed or are filled with debris, preventing them from functioning as they should.
In addition, Chesky said that malfunctioning drainage systems will also cause flooding. “They’re all tied to retention ponds and detention basins on your site, so that’s the ultimate point of discharge of your drainage systems, and if the ponds and detention basins are not functioning properly that will also result in flooding,” he noted.
Chesky also said erosion from too much flow can lead to flooding, which he noted can be the result of extreme stormwater events such as last year’s Hurricane Ida which caused areas to flood that don’t normally do so. “That was a result of an excessive amount of water that fell and already saturated soils from previous storms, causing an inundation of stormwater systems,” he said.
Chesky added that issues can also stem from improper grading causing water to collect in low spots. He explained that oftentimes, grading problems are the result of a construction defect. Chesky said that when a site is originally built, there are grading and drainage plans that the contractors are supposed to build in accordance with. However, sometimes the contractors don’t follow the plans exactly or make a mistake while other times the plans may work on paper but not realistically.
“Original grading might not work so over time, it might rear its ugly head and cause a drainage issue,” said Chesky. This can happen with the grading around a foundation that may be flat or back pitched, causing water to accumulate around the perimeter of the building. He said it can also happen in a swale between two drains where the swale might be flat and wasn’t finely graded, causing holes everywhere that hold water.
Chesky said that in paved locations such as roadways or in the immediate areas around the foundation, the standard for standing water is 24 hours. “So if you see standing water in those locations within 24 hours, then it’s a defect,” he noted. “In sump pump discharge locations or in swales where water is expected to travel, the standard rule of thumb is 48 hours where standing water is allowed. But it should not be there for any longer than that period of time.”
According to Chesky, pipes and catch basins are protected from the environment since they are underground and should last indefinitely. “Lawn drainage really should last forever,” he said.
However, he noted that drains will require repairs, particularly the ones that are in the roadways. Chesky said that those repairs are typically done during a roadway improvement or resurfacing project. “That’s the time when every drain in the roadways should be inspected and repairs done,” he noted.
Chesky said that drainage systems are not considered a reservable component because a reservable component needs to be inspectable and have a determinable life cycle. “So if the pipes are underground, concealed from weathering and degradation from UV and other things, particularly if they’re plastic or even concrete, they have a very long life cycle well above and beyond the 30-year typical life cycle that we look at for reserve studies,” he noted. “And it needs to be inspectable. Without actually being physically able to see it, we can’t determine what the life cycle is. We don’t know how long it’s going to last.”
However, although drainage repairs are unforeseen and therefore not reservable, Chesky emphasized that it’s important to budget for them somewhere, whether it be in the operating budget or separate maintenance fund.
Chesky noted that the worst thing for an asphalt paving system is the introduction of water into the subgrade or the soils that are supporting the asphalt. He explained that new asphalt is uniform and doesn’t have any cracks in it to allow water in, but as asphalt ages, cracks form. If those cracks are not maintained and sealed, water will penetrate through them into the subgrade soils.
“The soils will become saturated and lose their structural stability, so as a truck drives over them, that asphalt will now flex more than if it was dry and solid. If it flexes and it’s brittle, it’s going to crack more and potentially fail at a greater rate,” said Chesky. “So what you want to do is maintain your asphalt, keep your cracks sealed and filled, sealcoat your roadways, and resurface them regularly so that the subgrade is maintained forever. If you let it go too long, and you allow that subgrade to become saturated and fail, then you’re going to end up having to reconstruct the entire roadway as opposed to just doing the normal resurfacing and maintenance activities.”
Chesky said it’s also important to maintain retention ponds as they are integral to the drainage systems. They need to be maintained and inspected, as well as dredged periodically every 20-30 years. Otherwise, he said there is a possibility of flooding occurring in an extreme storm event.
In addition to flooding, Chesky said that poor drainage due to improper grading around the perimeter of the building can also cause water infiltration in basements and crawl spaces. He explained that high groundwater conditions can cause water to penetrate through the foundation wall, come up through the foundation, or come through the perimeter where the foundation slab meets the foundation wall. He said that there is typically a joint between the slab and the wall which is where the water can come up through.
Chesky added that foundation walls are typically built and coated with a waterproofing material called damp proofing which only lasts about 30 years. “We commonly find on buildings older than 30 years that are having water infiltration issues through the foundation walls, that there’s a failure of that damp proofing,” he said. “Unfortunately, the only way to repair that is to excavate the perimeter and redo the damp proofing.”
Chesky noted that some buildings should not have been built with basements or crawl spaces. “It’s all dependent on the soils and the water table. If there are high groundwater conditions, especially during extreme storm events, water infiltration through basements and crawl spaces is very common,” he said.
The damp proofing may or may not be considered a reserve item, noted Chesky. He said it depends on the layout of the community and whether or not they have basements, along with a history of water infiltration. “It’s also not just about the failure of the damp proofing, but it’s also the groundwater conditions. So you can have failure of damp proofing but not have groundwater conditions that would cause the water infiltration,” said Chesky.
Most importantly, Chesky said that for drainage systems, maintenance is key. “A lot of associations don’t think they need to do anything with their stormwater systems, but it’s very important to have them cleaned. Every couple of years, have the drains in the roads at minimum cleaned out with a vac truck, pull out all the leaves and debris in the drains. Retention ponds need to be inspected and potentially dredged,” he noted.
Chesky added that it’s important to know when there is a drainage issue, there are solutions. “If there is an ongoing problem with an area of poor drainage, hire an engineer to come out, assess it and give you a plan to remediate it, and hire a qualified contractor to do that remediation. The worst thing you can have is an area that retains water. It’s unsightly, it’s potentially a health hazard, and it’s a breeding ground for insects,” he said, adding that there are also solutions for issues related to foundation walls and slabs.
Although the issues themselves are site specific, there are certainly methods and solutions to address all of it, said Chesky.