catch basin

Catch basin upkeep critical as potholes proliferate

Recent news reports suggest property managers could be in for a bumpy spring
Thursday, March 22, 2018
By Rod Campbell

Have there been more potholes this year than in previous years? An informal survey says yes.

Since the start of 2018, various media outlets in Windsor, Simcoe, Ottawa, Toronto and Hamilton have quoted municipal road operations staff who say they are dealing with more potholes this year than previous years. The amount of snow and precipitation this winter, along with frequent freeze-thaw cycles, is apparently to blame.

And parking lots, including on condo properties, are not immune from these conditions.

A great way to prevent potholes is to stop water from getting into and under the pavement, where it can cause damage, with effective drainage. Parking lot drains, which are often referred to as catch basins, collect storm or surface water.

But catch basins can stop efficiently moving water away for many reasons.

One reason problems arise is the catch basin is secured deep in the ground, below the frost line. When the frost settles into the ground during winter, the catch basin will stay in place as it is designed to do, and the asphalt or road surface will often heave. When the warm weather returns, the asphalt moves again and the catch basin stays put, or at least does not undergo as much movement as the asphalt. This, and the several dissimilar materials used to construct a catch basin — the steel assembly, concrete basin and surrounding asphalt — expand and contract at the same time, but at different rates, so something’s got to give.

Usually the asphalt around a catch basin is what gives. It will shift, and water will pool around the basin rather than draining through the hole in the catch basin. Having a contractor lower the catch basin assembly will solve this problem. The process involves removing grade rings, also called risers or modu-loc, located under the assembly. If there are no grade rings, a low-rise assembly can be installed to solve the pooling water problem.

It’s important to assess why water is pooling around a catch basin before this work begins. The contractor should open the assembly and inspect the grade rings, the bottom of the basin, and the pipes entering and exiting the basin bottom. There is no point in fixing the outside of a catch basin or the surrounding asphalt if the problem is inside.

The inside of a catch basin may fail due to heavy traffic and wear and tear over time. Broken grade rings need to be replaced. If the bottom of a basin cracks, it too needs to be replaced. The space surrounding the pipes entering the basin — called the annulus — may need to be repaired or filled. Otherwise, water draining out of the basin will take the path of least resistance, flowing outside the pipes and creating a cavity where there shouldn’t be one. Water should drain away through the pipes into the storm sewer system.

Similarly, when the asphalt surrounding a catch basin cracks, water will take the path of least resistance, entering at the lowest point under the assembly and wearing away the surrounding asphalt.

Contractors should also look for obvious damage to a catch basin, such as cracks or pieces missing from the assembly. A cracked assembly should be replaced because its brittle steel will snap and fail. When pieces are missing from an assembly, the snow plow is usually to blame. If an assembly shifts during the winter, as they often do, snow plows can hit and break them.

Asphalt in a parking lot should slope toward the catch basins so water naturally flows into the basins. In parking lots with a limited slope, standing water can become difficult, if not impossible, to move without completely removing and regrading the subbase. Aside from design flaws like this, which can require the costly repair and replacement of parking lots, regularly inspecting and maintaining catch basins — once or twice a year, in spring and fall — can prevent small problems from becoming bigger, more expensive problems.

Anecdotal evidence of potholes being especially problematic this winter serves as a good reminder of the importance of protecting condo properties from water damage.

Rod Campbell, president of the Catch Basin Authority, has more than 20 years of experience in the property management and construction business. 

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