Last week I got to thinking about flooding in southern Preston Hollow, particularly behind the Pink Wall and Northwest Highway … and it struck me. There was a solution to area flooding staring us in the face since March. Preston Place condominiums lot.
You see, currently we all know existing drainage can’t handle large, fast torrential rains, like the one we had yesterday. In the south Preston Hollow area and Northwest Highway, there is enough flooding to lift and move cars a few times per year. The thing with flooding is that first, you can’t change the rain. So the only other options are to either increase capacity or to control the flow of floodwaters to keep water off the streets.
As I wrote about yesterday, Diplomat suitor A.G. Spanos has put some anti-flood measures into their initial plan. But regardless of how generous they may be, without the city of Dallas doing their part to increase the capacity of the storm drains, it will be all for nothing.
I am aware that millions of dollars remains unspent from the two previous bonds that was earmarked for flood control. It remains unspent in some cases because the work wasn’t able to be completed. For example, in south Preston Hollow, increasing flood capacity would necessitate work on University Park’s side, which apparently they are unwilling to do (perhaps Dallas shouldn’t have allowed the new HPISD school to be built in Dallas without a little support for flood control … but I’m not in politics).
So anyway, back to Preston Place.
Imagine if the city purchased Preston Place with some of those unused millions and sealed off its already-built underground garage to use as a reservoir for storm runoff? The money would be invisible to the overall city budget and the neighborhood would have the bathtub it needs to sequester water until existing drainage can handle it.
A little math
Let’s say the garage takes up 1.5 acres or 65,340 square feet. If we assume a height of 10 feet, the total volume is 653,400 cubic feet of water or 4.89 million gallons of water. Were the neighborhood to point drainage to this underground vault, it would hold back 4 inches of runoff from 45 acres of land. Assuming we got an 8-inch downpour, that’s half the total water volume removed from the drainage system until the storm passed and could be safely be released. My calculations may be off by a little, but I think I’m close. The garage may not be 10 feet tall, but I think it covers more than 1.5 acres of the nearly 2-acre site. So, close.
If the neighborhood wanted to utilize the water, the same pipes that send the water to the garage could be reversed to water nearby lawns, reducing the burden on the city supplies. Of course to maintain full capacity, the vault would have to be cleaned of silt build-up, perhaps annually – something the City could get the neighborhood association to pay for (thus ensuring it would be done).
As a bonus, the roof of the garage could be landscaped to provide a needed 2-acre neighborhood park (that would in turn hold water in its soil during rains). Certainly the weight of soil and plantings wouldn’t be an issue as it previously held a three-story building. It would be slightly raised from ground level, but there are already staircases on all sides leading up to the top of the garage that could be repurposed. The park could also be neighborhood maintained through payments to the neighborhood association by the nearly homeowners’ associations.
All in all, a little crazy certainly, but it could definitely work if Dallas thought outside the box and saw this as the opportunity to locally solve area flooding while providing parkland the area desperately needs. It would also go a long way to allaying neighbors’ concerns on increased density.
I sent this idea off to City Hall last week. What say you?
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