Drainage is an essential component of a long-lasting, low-maintenance asphalt parking lot. If water does not drain well from above and below your parking lot, problems like cracking, warping, and potholes can develop. Lacking drainage can significantly shorten your parking lot's life and lead to various expensive and ongoing repairs. Our expert on asphalt installation, repairs, and sealcoating in San Andreas, CA, share these tips for saving your parking area from poor drainage.
Knowing the signs of inadequate drainage can help you identify issues early before they cause significant damage that compromises your parking lot's structural integrity. First, pooling water is much more than a nuisance to your parking lot. Asphalt is a slightly porous material, so the standing water can seep into the pavement's surface. If it freezes and expands, your pavement will develop damage. Cracks or potholes will form that allow more water to intrude into the deeper layers of your asphalt, where it can compromise the structural integrity of your pavement.
Next, crumbling may be present in potholes. Continued water intrusion leads to widening holes as the edges crumble away constantly. Crumbling is also common around asphalt edges, especially when they are not butted against curbs. This crumbling is caused by water washing away the base materials and dwindling away pavement support.
Also, sinking happens when water gets underneath the pavement and washes away base materials. When weight is applied to the surface, it sinks into the newly introduced space and leads to warped surfaces or low pavement areas. This develops into a vicious cycle when neglected. The pavement falls and allows water intrusion into the low spot, which develops into further damage. You might also notice cracks forming from the warping that sinking causes.
Finally, raveling is the process of asphalt aggregate loss where the gravel in the asphalt mixture comes loose. This process results in loose gravel and an uneven faded paved surface. There are various causes for raveling, like pooling water, age, and sun exposure.
Poor drainage does not always mean you have to replace your lot entirely. Instead, you can install drainage solutions on existing lots to prevent further damage and improve drainage abilities. First, the shoulders of many lots are installed with storm drains present. If it is impossible to install actual storm drains on your lot, you can have shoulder drains installed instead. These drains are lower gutters or troughs installed along your lot's curbing. These drains guide the water into municipal storm drains close to the street or nearby catchment basins.
Next, water flowing from your building or landscaping, especially following heavy rainfall, can pool in your parking area and cause issues. Catch basins are large drains, like storm drains, designed to capture the water as it drains to low points on your pavement. They are also commonly installed directly in the water flow path from a downspout or roof to prevent it from ever pooling on the pavement.
Finally, your parking lot is graded to guide water to existing shoulder drains and catch basins in the most ideal circumstances. Trench drains can solve the issue in situations where a lot is not graded correctly and water pools on the pavement. Your paving contractor will cut a trench in your lot at the low point where moisture collects. Then the channel is equipped with a drainage trough level with the pavement so as not to interfere with traffic. The contractor will properly grade the trough to guide water through and to the nearest drain.