Ditch-digging with air Rescue: A new "shovel" that uses a powerful stream of compressed air helps an environmentally sensitive project in Annapolis.

October 18, 1998|By S. M. Tueting | S. M. Tueting,SPECIAL TO THE SUN

How far do you go to save a couple of trees? Ask John Pilli and he'll say you do whatever it takes -- even blowing the dirt away.

The Annapolis area developer knows what he's talking about.

That's because the president of Pilli Development Co. Inc. has had to use a new "air shovel" on an environmentally sensitive project he's undertaking in downtown Annapolis. But Pilli is not alone in dealing with a challenging building site.

As efforts to limit suburban sprawl in Maryland have gained support and prime sites have became scarce, developers are forced to go to greater lengths to accomplish their trade.

Technology such as the air shovel is coming to the rescue, making some previously impossible projects doable.

In Pilli's case, he owns a third-of-an-acre lot that he wanted to develop in the heart of Annapolis -- at St. Mary's and Compromise streets -- opposite the Annapolis Marriott Waterfront Hotel and the Annapolis Yacht Club.

He envisioned building luxury townhouses on the site, but encountered several obstacles, including zoning and environmental problems, and trees -- big trees.

City officials insisted he preserve a 75-foot tall, 57-year-old sycamore tree and a 50-foot tall, 30-year-old silver maple.

But preserving the trees might mean substantial revisions in the project, requiring that the four proposed townhouses be moved farther from the trees, plus possible building and zoning code changes, Pilli said.

"There was a lot of communication between the city and us," he said during a recent visit to the job site.

Before construction could get under way, Pilli and his company had to find a way to dig around the trees without damaging their root systems -- a task too delicate for a backhoe to handle, Pilli said.

The solution: a newly developed shovel that operates with compressed air.

The shovel looks more like a long tube with a nozzle at the end than a traditional spade.

Designed by a landscape architect in California, the Air-Spade 150/90 uses a special nozzle of finely turned stainless steel to focus a laser-like jet of air moving at about 1,800 feet per second.

The Air-Spade has a rigid barrel with a spring-operated on/off valve and is powered by a standard industrial air compressor.

The stream of air turns porous substances such as dirt into the consistency of fine sand but without harming nonporous items such as roots or pipes, Pilli said.

And what made the Air-Spade perfect for the townhouse project was that, unlike similar devices that use water instead of air, there were no environmental problems with the Air-Spade, said James Urban, an Annapolis landscape architect and urban tree expert who is a consultant on the Pilli project.

A more traditional water method of excavating around the trees' root systems would not have worked because the property was within the Chesapeake Bay "critical area" and runoff would have damaged the bay, Urban explained.

'Groundbreaking'

Without the air shovel, Pilli "would have been able to develop the site, but not with saving the trees," Urban said. "That's what's groundbreaking."

Pilli agreed. "Without this technology, the project might not have been economically feasible."

The technology is so new that the Air-Spade used by Pilli's crew was only the fourth one manufactured. At a cost of about $2,000, Pilli said the device is relatively affordable.

One worker who was using the Air-Spade recently to remove about 8 cubic yards of dirt -- a small dump truck load -- from around the trees said the device was relatively safe and easy to use, but messy and a bit tedious.

Once pulverized, Pilli explained, the dirt must be vacuumed out to remove it.

Wearing a white workman's jumpsuit, John Zeinog of Arnold joked over the high-pitched whine of the air shovel that he was a "root-saver." He guided the tool's jet of air so that it dissolved clumps of earth to reveal a complex network of roots.

The spade's air pressure was so strong it kicked up a cloud of dirt that turned the front of Zeinog's jumpsuit a shade of chocolate brown.

After the dirt was removed from an 18-inch ditch around the perimeter of the townhouses, workers sank the buildings' footings around the roots and laid gravel between the footings. Concrete beams were placed so that the roots could continue to grow underneath the four, custom-designed townhouses, Pilli said.

The townhouses, ranging from 3,200 to 3,900 square feet, are priced from the mid-$600,000 range and include underground parking. The basic design calls for three bedrooms and an office, Pilli said.

Despite his company's work to preserve the trees, Pilli said he won't know for sure how successful the company has been until a few years down the line.

Preservation difficult

And other landscape professionals warn that despite the wonders of technology, preserving trees and other natural elements of a site can be extremely difficult.

"I'm all for saving trees, but within reason," said Becky Sunday, owner and president of RJ Sunday Landscaping Inc., stressing that large trees can be especially difficult to preserve once their root systems have been disturbed.

Pilli, though, is optimistic.

"Maybe you can do development and protect the environment," said the Annapolis area developer. "There's middle ground here."

Pub Date: 10/18/98

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