The reasons are plenty, but the main one is this: Impervious surfaces, such as roofs, traditional concrete and asphalt, create massive amounts of runoff, which puts an often-unbearable load onto local stormwater systems.
This is where pervious shines.
Believe it or not, as much as 5 gallons per minute can pass through a square foot of pervious concrete. That’s a rate fast enough to handle 8 inches of rainfall every 60 seconds!
In Whatcom County, 8 inches of rain in a month is a huge amount. But drainage systems do get overburdened quite often in heavy storms, especially as water runs off of roofs, roads, driveways and other impervious surfaces and is collected by downspouts and drainpipes into certain areas.
For example: A house with 2,500 square feet of roof area, in a storm that’s dumping an inch of rain per day, is collecting a little over one gallon of water per minute. That’s an awful lot of water, but with the aid of pervious concrete, it’s possible to handle all of the water without even taxing the city’s stormwater system.
Related: Want to run your own calculations on the amount of water produced by a certain storm? The USGS has created a handy calculator for this purpose.
When installed by a knowledgeable, licensed contractor, pervious concrete can be a huge help in managing drainage, runoff and stormwater issues.
The prevention of runoff is one major benefit to pervious concrete. But that’s not all. Here are a few other ways that pervious can benefit a home under construction:
- As a filter for pollutants: Research has shown that as much as 99 percent of oils that drip onto pervious pavements are trapped by the voids in the pavement and biodegraded before they even reach the underlying soil. On the other hand, oil that drips onto traditional pavements is often carried away by runoff, potentially polluting nearby bodies of water. Because pervious concrete captures the “first flush” of rainfall and allows it to seep into the ground, the polluted water can be treated by natural processes. Costly and land-consuming stormwater retention areas, then, may not be needed.
- As a drainage border: A relatively narrow strip of pervious around a conventionally paved area, such as a driveway or parking lot, can significantly reduce runoff. Water may sheet off of the main surface, but when it gets to the edge, it seeps into the ground. This is a great way to reduce the need for water management systems and reduce the load on city services.
- As a water recharger: One of the biggest problems with typical stormwater systems is that the rainwater collected in one area — on your property, say — is piped off to be handled at another location. Over time, the water table under your property can be diminished. Pervious concrete, though, allows water that falls on your property to seep into the ground and recharge the water table on your property.
The pros at Custom Concrete Contracting are experts in all things concrete. They can install traditional concrete foundations, footings and retaining walls, and they’re also Northwest Washington experts on pervious concrete. Give them a call today to discuss how pervious concrete can benefit your construction project.