A Closer Look at Catch Basins: Part 2

Rose PavingRose Paving / February 23, 2011   |   Articles / Catch Basin
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Equipped with an adequate number of catch basins strategically placed in a parking lot, it then becomes important for facility/property managers to perform routine inspections and cleaning of the catch basins.  Inspections should be conducted with the assistance of a reputable parking lot maintenance contractor.  He or she can help you look for the following potential defects:

Defect 1: The catch basin is higher than the surrounding asphalt, causing a trip hazard and standing water around the basin.  This occurs when the stone sub-base underneath the surrounding asphalt settles over time and the pavement becomes lower in elevation than the concrete basin.  To remedy this situation, a contractor can remove the surrounding asphalt and lower the basin by removing concrete rings to alter the height of the iron frame.

Defect 2: Sinkholes are developing in the asphalt adjacent to the basin.  This is the result of one or two occurrences.  The first is when water penetrates the basin through gaps in rings, barrels, or at inlets and erodes the stone sub-base in the surrounding asphalt.  If action isn’t taken quickly to remedy this situation, water will erode the concrete basin and further exacerbate the problem.  The second is when the stone base adjacent to the basin has settled and cannot support the surrounding asphalt.  Depending on the extent of the erosion, it may be possible to remove and replace the surrounding asphalt and fill it to a greater depth or it may be necessary to replace the entire basin structure.

Defect 3: Sinkholes are developing in areas away from the catch basin.  This occurs when pipes, leading to or from the basin, have collapsed and water has begun to erode the stone base supporting the asphalt.  Older parking lots tend to have clay tile pipes which can shift or break over time.  Oftentimes, this is evidenced by a large amount of stone at the bottom of the basin even if there are no holes or gaps in the basin itself.  In effect, the stone is being washed through the broken pipe and collects in the basin’s sump.  In this situation, contact a plumber to identify the location of the collapse or perform exploratory excavation in the suspected location of the collapse and replace the damaged/broken line using PVC piping, which lasts much longer than clay tile.

Defect 4: The frame of the basin has shifted on an angle.  This occurs when the concrete rings supporting the iron frame have become unstable, shifted, or completely eroded on one or all sides.  Concrete rings are the weakest link in the basin’s structure and will be the first to deteriorate.  They also provide an entry point for water if not properly bonded to other structural components using mortar or, ideally, a tar-like substance known as mastic.  To remedy this situation, replace the rings using a proper bonding agent.

In addition to performing remedial repairs on catch basins, it is also important to regularly clean each basin.  Depending upon the site, catch basins can fill up with garbage, leaves, and mud, leaving the bottom of the basin covered.  This prevents seepage of the storm water into the ground.  During a heavy downpour, a clogged basin can fill up quickly and overflow onto the parking area.  Routine cleaning will help catch basins function properly.

Ultimately, by taking the steps to assess, inspect, and maintain the drainage system on your parking lot, you can decrease the potential for flooding and other water damage to your asphalt investment.  Furthermore, it is always better to be proactive with parking lot maintenance than reactive to untimely emergencies, especially when it concerns the safety and convenience of your customers and employees.

This excerpt is from an article written by Rose Paving Company.  First published in PRSM Magazine in April 2008.