Storm basins (manholes) and curb inlets allow water to drain from within the area of the parking lot into storm sewers. Over time these structures will move or settle differently than the adjacent pavement causing drainage challenges. When the elevations of these structures shift it reduce the effectiveness of the drainage by not allowing water to enter the sewers and instead seep into the underlying asphalt structure. Periodic maintenance should be completed to ensure that the elevations of storm drains are flushed with the asphalt for drainage as well as snow removal concerns.

Sinkholes will develop adjacent to storm sewers where water seeps into the asphalt pavement through openings and cracks and burrows its way down towards the lowest elevations but NOT through the sewer openings. When this happens, the water erodes the underlying areas and the pavement creates an air pocket to develop. When the pocket collapses a sinkhole is formed very similarly to a pothole in a roadway. A sinkhole left unattended can become a substantially more expensive repair if deferred and pose a significant safety liability.