By Dave Majewski.
“Asphalt” is not necessarily a two word phrase placing blame.
This contaminated runoff is one of the most serious problems that plague Buffalo and Western New York. It not only jeopardizes our natural waterways and our health, it puts increased strain and cost on the entire system and on engineers that are tasked with managing water quality and quantity.
Asphalt paved parking lots also – by virtue of non-sustainable and destructive construction practices – create lost green spaces, erosion, and compaction throughout adjoining areas, which each promote runoff.
Parking lots are an economic necessary “evil.” We must have them and they must be paved for economic reasons. Permeable paving is a doable option that certainly works – but it is seldom cost effective on mid- to large-scaled projects and it requires more maintenance. Permeable systems don’t offer the green spaces.
Asphalt parking lots in Buffalo, at a size of approximately 30,000 square feet that may accommodate approximately 100 cars, will generate approximately 75,000 gallons of UNTREATED and CONTAMINATED storm water runoff from each parking lot. This 30,000 square foot figure is a small parking lot.
You can use this general rule of thumb: 10,000 square feet of surface area generates approximately 25,000 gallons of untreated runoff, annually, in Buffalo and WNY.
In asphalt parking lots, the following contaminants exist and are untreated as they flow in to our combined storm sewer systems:
- Petroleum or tar from the asphalt itself, including the top sealer;
- Petroleum, oil, and lubricants (POL’s);
- Windshield washer fluid and deicing agents (the label indicates, this product “cannot be made non-toxic”);
- Salts from winter salting and plowing;
- Radiator fluids, including anti-freeze fluids and other corrosives;
- Pesticides from adjoining green spaces, (e.g., neighbor’s green spaces that get treated seasonally);
- Pet feces from adjoining green spaces;
- Rust debris falling off the undersides of many vehicles;
- Alot of chrome debris from bumpers and wheels;
Many diesel and gasoline leaks; and, - Unknown chemical debris from runoff that is generated in the back of pickup and small commercial truck beds as rains flood these beds and the trucks drive off.
Here is a helpful Scientific American article referencing an EPA study. The US EPA has done several studies on this topic and there are many other independent and governmental links with very good information.
Here is a link to a lecture given on this topic in September of 2009.
There are a number of ways to mitigate or eliminate contaminated runoff from asphalt parking lots. Here are some ways that are best if designed and specicified prior to construction:
- Low Impact Development (LID) – Green Parking lots with bio-retention (BR) cells (257 Lafayette), which also gives you the option to add attractive, ecological and functional green spaces. These can be educational and benefit the community. They offer the incentive of meeting quicker board approval and inspections expediting.
- Green BR Cell Islands in Parking Lots – The contaminated runoff is intentionally directed in to green spaces that are designed and engineered to accommodate this impure runoff. It purifies the runoff up to 99 percent and can drastically mitigate and even eliminate any runoff in to the combined system.
This story originally appeared on the GrowWNY website, a hyperlocal source of information about living green–powered by more than 150 organizations collaborating for our regional environment.
Reprinted by permission.