Dan Sorenson / Arizona Daily Star

More Photos (1):

Other articles by Dan Sorenson:

All-electric sedan here Jan. 4Changes to building draw heat$900K in grants offered for ethanol, biofuel switchUPS Supply Chain gives more details on unit shutdownUPS' logistics arm closes, lays off 13Providence Institute suddenly shuts downMajor Tucson yoga center closes, offers refundsLocal Honeywell plant has international reachTucson to get new LeafQuite a different motor dealer

Health Care
RLM Services, Inc.
Orthopedic Assistant-CMA Sales and Marketing
Ever-Ready Glass
Glass Sales Health Care
BENSON HOSPITAL
RESPIRATORY THERAPIST

Tucson parking lots have long been hell on Earth — for vehicles, their sizzling passengers, wildlife and the environment in general. Only a buzzard, catching an updraft off one of these heat islands, could love them.

But there's a partial glimpse of the kinder, less hellish parking lots in Tucson's future at a new Target big box store at 4400 N. Oracle Road.

The Super Target, set to open in October, employs some of the elements that will be required under a new city rainwater harvesting ordinance for commercial property that will go into effect June 1, 2010 .

The lot's landscaping, designed by Tucson's ARC Studios Inc., was planned before the ordinance was written and passed, but landscape architect Eric Barrett said it incorporates many of the crucial features: depressed elevated planters and tree wells, curb slits and contoured pavement so water can flow into the plant areas by gravity, low-water-use, and mainly native vegetation.

The lot will be able to handle up to 112,000 gallons of water per rainfall.

The old parking lot, which Barrett said had just a few trees, would only hold a small fraction of the water from a rainfall. The redesigned lot has about 300 trees, including desert willow, Phoenix hybrid mesquite, Desert Museum palo verde, sissoo and "tons of shrubs and accents."

The new layout appears to work.

In the heavy rain that hit the Target lot around 6 p.m. Wednesday, water flowed to the catchment areas and soaked in. There was almost no sign of water five minutes after the rain stopped.

An existing city ordinance already requires that commercial parking lots have trees, and sets the number and spacing. But the new rainwater ordinance requires that 50 percent of their annual water come from active or passive rainwater management, said Barrett, a partner in ARC Studios.

And while an amazing amount of rainwater can be harvested from a commercial parking lot and other hard structural surfaces — such as roofs and sidewalks — Barrett said the 50 percent rainfall requirement could cause a reduction in the amount, or at least a change in the type, of vegetation planted.

This kind of "green" work is becoming more common, said Ben Shunk, project manager for Adolfson & Peterson Contractors' Tempe office, the general contractor for this and several other Target projects in Tucson and the Western U.S.

"Target's trying to make a big green push right now," Shunk said.

Rainwater harvesting doesn't make the project any more difficult, Shunk said, but it does require coordination between a project's civil engineering firm — which handles drainage from the property — and the landscape architect.

Water catchments, such as the depressed planters and tree wells, can undermine pavement, if they're not properly designed, Barrett said. He said the usual answer is to use a mixture of materials that hold the water in the planters or other depressions.

"It perks back into the ground and replenishes the aquifers and all that good stuff," Shrunk said.

"We did the (Reid Park) zoo remodel, as well, and that went LEED Platinum," Shunk said. LEED Platinum is the highest level of a set of energy efficient and environmentally benign building standards.

On the zoo project, Shunk said the company used pervious asphalt — asphalt with openings to allow rainwater to soak into the ground below. "It drains down to a layer underneath and then to an aquifer layer and to the trees," Shunk said.

"Through the openings in the asphalt, it can perk through, get to the dirt underneath, or you can harness it underneath and get it to go where you want it to go," Shunk said.

That could include cisterns or other storage devices, but the Target project does not employ active harvested rainwater irrigation such as pumping stored water through an irrigation system.

The Target project has an irrigation system, using city water, to supplement the harvested rainwater during dry periods.

And while the new ordinance only requires that the rainwater harvesting system provide half the water needed annually by plants, in a typical year, Barrett said even the pre-ordinance Target irrigation system should only be needed in the three months before the monsoon.

An irrigation system to supply water to plants during dry periods is also required under the new ordinance, Barrett said, but must provide precise watering geared to each plant's needs and based on conditions.

He said most irrigation systems overwater plants. Using sensors and an evapotranspiration system, Barrett said, can minimize use of active irrigation.

"Your irrigation system has to be metered to provide different amounts for each plant," Barrett said. He said the evapotranspiration gear takes into account the type of vegetation, rainfall, humidity, temperature and wind, all by ZIP code.