Green Options For Your Driveway
A recent question from one of our readers re: ‘green driveways’ inspired me to do some research on the topic. From what I can tell there are two main approaches:
1) creating a driveway that is literally ‘green’ with vegetation, and 2) using some form of porous concrete or asphalt.
Both of these options have the advantage (over traditional driveway paving) of allowing rain water to drain into the ground, thus helping to remove pollutants and lessening the burden on storm sewers and local water bodies. The vegetative option has the added advantage of eliminating (or at least greatly reducing) the ‘heat island’ effect associated with paved areas, not to mention offering a certain natural aesthetic appeal.
Let’s look at the vegetative options first. Of course the easiest approach would be to simply rip out your driveway then plant grass – the downside of this approach however, is that over time the earth will get compacted and ruts will form. In order to maintain good drainage some sort of structural lattice is required – typically made of concrete/stone or high density plastic.
One example of the plastic lattice approach is Grasspave2, one of a number of innovative products offered by Invisible Structures Inc. Here is a blurb from the Grasspave2 page:
Grasspave2 is a structure which provides incredible load bearing strength while protecting vegetation root systems from deadly compaction. High void spaces within the entire cross-section enable excellent root development, and storage capacity for rainfall from storm events. Stormwater is slowed in movement through and across Grasspave2 surfaces, which deposits suspended sediment and increases time to discharge. Suspended pollutants and moderate amounts of engine oils are consumed by active soil bacteria, which are aided by the system’s excellent oxygen exchange capacity.
Be sure to check out the Invisible Structures website – they have a variety of intriguing drainage solutions.
If you are looking for some excellent ‘how to’ info on building your own green driveway I highly recommend checking out this HGTV article: A driveway that looks like a lawn. It takes you step by step through the process of installing your own turf driveway using a plastic lattice.
Ok, moving on the the topic of ‘porous pavement’…
There seems to be quite a lot of good info on this topic. Here is an exerpt from and interesting webpage about porous pavement:
What is porous pavement:
Porous pavement is a permeable pavement surface with a stone reservoir underneath. The reservoir temporarily stores surface runoff before infiltrating it into the subsoil. Runoff is thereby infiltrated directly into the soil and receives some water quality treatment. Porous pavement often appears the same as traditional asphalt or concrete but is manufactured without “fine” materials, and instead incorporates void spaces that allow for infiltration.
Why consider porous pavement:
Traditional stormwater management practices significantly reduce groundwater recharge has led to a number of environmental concerns in recent years. As infiltration decreases, base flows in streams are decreased and previously flowing, small streams now often dry up between rains. Homeowners and public water suppliers often rely on wells that tap groundwater. Without recharge, the threat exists that these drinking water supplies could dry up rapidly
If you are interested in learning more about this topic I highly recommend you check out the EPA’s Porous Pavement Factsheet
I also highly recommend this excellent article all about the advances in the porous pavement field (actually provides a lot of great info about alternative pavement options in general)