Sunken Catch Basin |
Catch Basins and Storm Drain Systems overflow
Otherwise known as storm drain inlets or curb inlets, catch basins are entrances to the storm drain system that consist of a grate in the parking area or a curb inlet along the perimeter of a parking area. Water, from rain and from irrigation, enters the catch basin which “catches” large sediment and debris while allowing the water to properly flow to and thru the storm drain system. As the sediment and debris builds up in the bottom of the catch basin (known as a sump), the catch basin sumps must be cleared periodically to prevent blockage of water flow thru the storm drain system.
If catch basin inlets and sumps are not cleaned periodically, sediment and debris will build-up. Build-up on the surface, at the catch basin inlet, will lead to water not flowing properly into the catch basin, causing puddling or flooding. Build-up in the catch basin sump will lead to water collecting in the catch basin instead of flowing thru the storm drain system, which will eventually lead to overflow out of the catch basin and flooding problems on the surface.
Damaged gutter from failed drain |
Storm drain systems damage or failure
Storm drain systems are used to control rain, melting snow, irrigation, and other fluids that flow off of parking lots. Although most of the water is absorbed by surrounding landscaping in most cases, much of the run-off is collected in the storm drain system thru catch basins and curb inlets. Some of the signs that this system is not working properly are sunken pavement around catch basins and manhole. Sunken pavement around catch basins and manholes not only indicates problems with the storm drain system below (i.e., a broken pipe), but also leads to significant trip hazards for pedestrians. Often, the problem lies in the catch basin itself (i.e., a broken brick inside the catch basin structure). However, sub-surface issues must be investigated to avoid future problems, such as dangerous sinkholes.
Puddling
As the pavement surface, base and subgrade shift and change with weather conditions and aging, slopes and grades change forming depressed areas in the parking area. Slopes and grades are designed and engineered to allow water to properly flow to catch basins and curb inlets. As the ground conditions change, forcing the base and subgrade to change, the slopes on the surface of the parking area consequently change. If these changes reduce the slope to prevent proper water flow to catch basins and curb inlets, puddles will form. Puddling is an area of the parking lot that does not have sufficient slope to provide drainage, which has allowed puddles of water to form.
Sinkholes and depressions
Sinkhole |
Sinkholes are depressions formed by the dissolving of the subgrade by the water that circulates through it. As the subgrade dissolves, cavernous spaces form below the pavement surface. Once the space has become too large to support the pavement surface and/or traffic above, the surface collapses. Sinkholes can also form due to ground-water pumping from construction practices as well as when new water diversion systems are developed that change the subterranean drainage patterns. As fluid pressures change, the balance they create is lost and the underlying soil becomes displaced, causing the surface pavement to collapse.
Depending on the severity of puddling and sinkhole issues, most puddling and sinkhole problems can be repaired by cutting damaged or collapsed areas and using sufficient depths of gravel and asphalt to adjust to the proper elevation. Because sinkholes could be due to storm drain system issues (i.e., leaking pipes), potential problems are investigated after excavation and repaired as necessary before installing gravel and paving.
Remedy
Depending on the sub-surface issues presented in each case, two main remedies are usually used to correct problems with asphalt surrounding catch basins and manholes. If the problem is due to a minor problem with the catch basin frame or ring, elevation adjustment is a sufficient remedy. This includes excavating sunken areas and using gravel and asphalt to level to the proper elevation. If frame or ring replacements or repairs are needed, these will be performed before installing new gravel or asphalt. In some cases, instead of repaving with asphalt, Portland cement concrete is used as a support border to the catch basin.
If the problem is due to a more serious issue with the storm drain system, the perimeter will be cut and the catch basin will be excavated. A new catch basin will be installed to the proper elevation and the area will be leveled with gravel and asphalt as necessary to match the existing surface elevation.
If you are experiencing drainage issues, learn more about having U.S. Paving & U.S. Sealcoat solve your drainage problems. Ask for a Free Estimate and analysis of your drainage needs from U.S. Paving & U.S. Sealcoat, and put our 20+ years of professional experience to work for you.
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