The Problem with Standing Water in Parking Lots
When it rains, you might end up with a lot of standing water in your parking lot, which creates a safety hazard for the people who use it. If you’re a driver, your tires might have trouble engaging the pavement and stopping your car. If you’re a pedestrian, you might discover the usual “pedestrian refuges,” like medians, are flooded. And that forces you into harm’s way.
But the water isn’t just an issue for the people who use your parking lot. It’s also an issue for the parking lot itself. Water can weaken the constitution of your pavement and, over time, that can lead to cracking and breakage. Then, once your pavement is compromised, water can seep into those cracks and erode the foundation down below. That leads to potholes and expensive repairs over the long haul.
Creating Parking Lot Drainage
You don’t have to live with standing water in your parking lot. You simply have to create a system of drainage that’s really, really effective. But creating that drainage has quite a few moving parts, including:
1. Your Parking Lot Needs to Have a Slope.
You might think your parking lot should be completely level. But that actually creates a problem: it invites all of the standing water to stick around. So, the idea is to give your parking lot a bit of a slope, which encourages the water to leave. Here’s the key, though—you don’t want that slope to be so extreme that it interferes with the usability of your parking lot. You want that slope to be subtle. So, the rule-of-thumb is that your parking lot should have a 1-5% gradient.
2. Your Parking Lot Needs Curbs and Gutters.
As you’ve just read, the slope of your pavement ushers the water away from your parking lot. But where is all of that water headed? You want to route it all towards a drain, and the best way to achieve that is with a system of gutters (curb and gutter, valley gutter). You’re basically directing water to the place it needs to go…the storm drain system.
3. Your Parking Lot Needs to Have a Drain.
Okay, so this is where the magic happens. You need to have a drain that allows the stormwater to exit your parking lot. And the main consideration is the capacity of that drain. How much rainfall do you get? Is the water being routed towards a single drain? Or will multiple drains be sharing the workload? These are all important factors, because if you overload your drain you create a “traffic jam,” and you end up with standing water all over again.
4. You Need to Keep Your Drains Clear.
Not everyone makes this a priority, but maybe they should. Because if your drains are obstructed, they can’t really do their job. Take a broom or a rake and be sure to clear away any leaves, trash, and other obstructions. While you’re at it, give the rest of your parking lot a once over, too. Even if the debris is far from your drain, the second the wind picks up or it starts to rain, that junk funnels right back to your drain and creates a clog. In extreme cases, it may be necessary to clean the drainage pipes with a high pressure water jet.
When your parking lot has standing water, it creates a hazard for people and for the parking-lot itself. So, be sure to give your parking lot a slope, a system of gutters, and a high-capacity drain…because those puddles create a lot of headaches. Call Black Diamond today to learn more about how we can help with your drainage.