Some business owners don’t give much thought to their parking lot. They may hire the lowest bidder to throw down some concrete and call it good. But in a few months, they’ll be regretting that decision. There’s a science to a properly functioning parking lot, and grading and drainage play important roles in the longevity, safety, and usability of a commercial parking lot.
With 30 years of experience paving parking lots, the Asphalt Doctors are experts at incorporating the best drainage design. We break down the essentials of parking lot grading and drainage below.
Why Does Proper Drainage Matter?
Lost Customers
We’ve all seen a flooded parking lot after a big rainfall. Chances are, if you didn’t really need to go to that store or business, you drove away. Poor drainage can lead to lost customers for your business. And in a state with its fair share of unpredictable rain (and snow melt), those missing customers can add up.
Legal Issues
The consequences of poor drainage go far beyond lost revenue. Say a customer does park in your flooded lot and walks toward your building—only to slip and fall in a puddle. If they can prove that you knew your parking lot was dangerous and didn’t fix it, you could be facing a lawsuit.
Damage to Your Pavement
Beyond customers, however, standing water affects the quality of your pavement itself. Excess water can lead to cracks and potholes in your asphalt. This weakens the structural integrity of your parking lot, and it will need to be resurfaced or even replaced sooner than if it had proper drainage.
These damaging effects are even more pronounced in Colorado, where we have a more intense freeze-thaw cycle than other states. If your parking lot is full of standing water under the warm afternoon sun, it could freeze by that night. This means that each little crevice that water had pooled in will expand when the water freezes—leading to larger cracks across your entire lot.
Damage to Your Property
If your parking lot isn’t thoughtfully designed, water may naturally flow towards your building. This water runoff can lead to all kinds of issues, including flooding, blocked entrances or exits, and damage to the foundation of the building.
How to Design Your Parking Lot for Proper Drainage
There are a few techniques you can use to ensure water doesn’t pool on your pavement. Many commercial parking lots use a combination of these asphalt drainage solutions.
Grading the Asphalt
Sloping the pavement slightly allows water to flow where you want it to, such as towards a drain. A professional can recommend the proper grade for your lot based on the natural inclination of the property and where you want to funnel the water.
Catch Basins
There are several drain types you can use in your parking lot. A common choice is a catch basin. On the surface, a large metal grate is installed, which will allow water and small debris to pass through. Underneath this, a plastic or concrete basin allows the debris to settle, then redistributes the water into the larger wastewater system.
Trench Drains
Rather than directing all the water to a single catch basin (or two), a trench drain is a long, skinny drain that can collect more water at once. A parking lot will be divided by the trench, and either side will be angled downward slightly toward the long drainage system. Water is then removed via pipes underneath the lot.
French Drain
If you don’t want a visible drain in your parking lot, a French drain could be the perfect solution. This system uses a pipe buried in a gravel-filled trench. Water seeps into the gravel and then into the pipe, which redistributes the water off-site.
Using Permeable Pavement
One issue with drains is that they can become blocked from leaves, trash, or other debris. A workaround is to instead install permeable pavement, where the water passes through the concrete or asphalt itself. Similar to the French drain, this system works by having a layer of gravel underneath the porous pavement, which absorbs much of the moisture and then slowly releases it into the ground over a longer period of time.
Choose Asphalt Doctors for Your Grading Needs
At Asphalt Doctors, we’ve been helping business owners design efficiently graded parking lots for over 30 years. We understand Colorado’s unique climate and rainfall patterns, and we’ll help you design a parking lot optimized for proper drainage and long-term quality. Contact us today to see what your parking lot could look like.