This Monday, Houston City Council is holding a special meeting to consider a proposed ordinance that would limit parking in front yards. Specifically, it says the only permitted parking in front yards is:
(b) Two or fewer vehicles or pieces of equipment may be parked or stored in the front yard of a single-family or duplex residence provided the parking area is covered with an impervious surface.
So why do the cars have to be on an impervious surface?
Sec. 28-301. Purpose.
The purpose of this article is to regulate the parking of vehicles or equipment in the front yard areas of single-family or duplex residential properties to preserve the property values and esthetics of neighborhoods, prevent damage to underground utility facilities and to protect the environment against contamination caused by the leakage of automobile or other fuels, petroleum products or other harmful chemicals from vehicles or equipment.
In other words, part of the stated rationale for this ordinance is that parking cars on lawn is a pollution issue. However, parking cars on pavement is actually more detrimental to the environment than parking them on grass.
The EPA says that stormwater runoff from urban areas is one of the primary sources of pollution in streams, lakes, and estuaries. Paved areas are a significant source of this pollution since they drain quickly to storm sewers and then into streams. This has been recognized as an issue in Austin, where rainwater recharges the Edwards Aquifer, and the Texas Department of Transportation has implemented a variety of measures to clean oils and other pollutants runoff. According to this study and this study by the University of Texas’ Center for Research in Water Resources, the most effective technology for cleaning urban runoff is grass:
The effectiveness of grassy swales for treating highway runoff was evaluated by comparing the runoff at Walnut Creek, before and after passing across a swale. The grassy swale proved effective for reducing the concentrations of most constituents in runoff. The low runoff coefficient due to infiltration of runoff into the swale produced a large reduction (90%) in pollutant load discharged.
In other words, parking cars on grass is not a pollution problem; it’s a way to reduce pollution.
This ordinance as drafted could have other unintended environmental effects as well. One likely effect would be to cause many homeowners to pave their front yards so that they can keep parking vehicles in them. This would reduce green space and increase impervious cover, leading to more runoff and more flooding.
Due to all of these reasons, the use of grass in parking areas is actually increasing. Multiple “green paving” technologies exist to reinforce parking areas to withstand regular or occasional parking. One major application of this technology is at Reliant Stadium, where a 300,000 square foot “grasspave” parking lot (above) reduces stormwater runoff and the “urban heat island” effect while making the grounds more attractive. The proposed ordinance may make the use of this technology in residential applications illegal.
I can understand the desire to prevent people from using their yards as ad hoc mechanics’ shops or junkyards, and the proposed ordinance may help with that problem. However, it would likely also increase pollution and increase flooding. I doubt that’s the desired outcome. Surely more carefully crafted ordinance could deal with front yard parking issues without the unintended consequences.
The discussion in our forums is already underway, and its runoff is completely safe.
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on Friday, June 8th, 2007 at 12:30 pm and is filed under Uncategorized.
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