How to Save Your Parking Lot From Poor Drainage

Drainage is a key component when it comes to low maintenance and a long-lasting asphalt parking lot. If water doesn’t drain well from below and above the lot, problems like potholes, pavement warping, and cracking can occur. A lack of drainage can shorten the life of the parking lot by years, or at least lead to a lot of ongoing and expensive repairs.

Signs of Poor Drainage
Knowing the symptoms of poor drainage can help you catch problems early before major damage compromises the integrity of the parking lot.
Pooling WaterWater pooling on the lot is more than a nuisance. Asphalt is slightly porous, so that water will seep into the surface. If it freezes and expands, the asphalt suffers damage. Cracks can form, but often the result is a pothole. Potholes and cracks allow more water into the paving, where it eventually reaches the base material and causes even greater damage.

CrumblingYou notice crumbling in potholes. Further water exposure leads to an ever-widening hole as the moisture causes the edges to continue crumbling. Crumbling can also occur along the edges of a parking lot, particularly one that is not shored up with curbing. This is due to the water washing out the base material and removing the paving support.

SinkingWhen water gets beneath the asphalt it can wash out the base materials. The paved surface then sinks into the newly created space, which leads to low areas or a warped asphalt surface. This creates a cycle – the paving sinks, so water collects in the low area, and then more damage develops. Cracks may also form in the paving due to the warping caused by sinking.

RavelingRaveling refers to the process of aggregate loss on asphalt. The gravel aggregate in the asphalt mix begins to come loose. The result is loose gravel and a faded, uneven paved surface. Many factors lead to raveling, but sun exposure, age, and pooling water are the main causes.

Improvement Options
Poor drainage doesn’t mean that you need to have your lot completely replaced. There are drainage options that can be installed into an existing parking lot that will improve the drainage and prevent further damages from occurring.

Shoulder DrainageThe shoulders of many lots are designed with included storm drains. If installing true storm drains is not possible, your parking lot can use a shoulder drain instead. Shoulder drains are essentially lower troughs, or gutters, that run along the curbing that borders the lot. The drains route the water into a nearby catchment basin or into the municipal storm drain near the street.

Catch BasinsWater flowing off of the building or out of nearby landscaping, particularly after heavy rains, can pool on the parking lot and cause problems. Catch basins are large drains, similar to storm drains, designed to catch the water as it drains to a low area. They can also be installed directly in the flow path of water draining off a roof or from downspouts so that the water never has a chance to pool on the asphalt surface.

Drain TrenchesIdeally, the lot is graded so that water drains toward existing catch basins and shoulder drains. In the event that an area isn’t graded properly so pools form, trench drains can solve the problem.

Your asphalt contractor will cut a trench across the lot at the low spot where water collects. A drainage trough is then installed in the trench, level to the paving so it doesn’t interfere with traffic. The trough is graded properly so that water runs through it and to the nearest drain.
Contact JR Paving & Construction Co., Inc., for more information on repairing poor drainage in your asphalt parking lot.