Xeriscaping saves water, and money, at the world’s largest Naval Exchange

Employees from KN Lawn Service, Inc., which contracted to perform the installation and maintenance of the new Pearl Harbor NEX xeriscape, work their way down a flower bed planting pohinahina, a native Hawaiian shrub-like ground cover. The plant boasts silvery green leaves that will produce beautiful blue flowers.

For many, the image of Hawaii is a lush, tropical paradise. That’s true, in part. “People think of rain and our waterfalls and our great surfing,” says Matt Flach, landscape architect with Naval Facilities Engineering Command (NAVFAC) Hawaii. “But, at least here on the leeward side of Oahu, we don’t get as much rain.”

As a result of this desert-like microclimate, water-loving plants that fare well elsewhere in the Islands don’t always perform as they should, or they require significant amounts of irrigation in order to survive. With these factors in mind, Flach recently designed and oversaw the installation of a $500,000 xeriscape project at the Pearl Harbor Navy Exchange (click here to view) (NEX).

Courtesy of Naval Facilities Engineering Command Hawaii.
Matt Flach, NAVFAC Hawaii’s landscape architect, directs the planting of native pohinahina in a long, narrow flower bed area on the outer rim of the NEX parking lot.

The scope of the project was tremendous. The Pearl Harbor Exchange (a mall-style retail store for members of the military) is the largest NEX in the world, and the xeriscape makeover was completed not only on the two entry roads leading into the complex, but also on islands scattered throughout the massive parking area. In total, the project included some 96,000 square feet of beds, involving the removal of the existing landscape plantings and the installation of nearly 59,000 drought-tolerant plants.

“When the Pearl Harbor NEX was built, they wanted it to be pretty—with nice looking buildings and lots of islands in the parking lot, to break up the asphalt jungle,” explains Denise Emsley, public affairs officer with NAVFAC Hawaii. However, she adds, the plants that had been originally installed were not appropriate for the setting.

“All of the islands are in the middle of a parking lot, so it gets very hot with the asphalt all around. They were getting beaten up by the heat and the sun, and they demanded a lot more water, which is something we’re trying to conserve,” explains Flach.

In some cases, water conservation is even mandated. Beginning in 2010, all federal agencies—including the Navy—are required to reduce water consumption by 2 percent each year until 2015. Outdoor landscaping is obviously one place that base commanders are looking to save water, making xeriscaping an attractive option.

In addition to using significant amounts of water, the existing plants were also posing a safety issue in the parking lot, adds Flach. “Some of the shrubs were getting to 4 or 5 feet tall, so with pedestrians walking and cars driving all around, people were having a difficult time seeing through and around them.” That, in turn, was leading to increased maintenance costs for pruning.

Flach had past experience at other naval installations for all of the plants he included in his plans for Pearl Harbor NEX. Still, this was the first large-scale installation of its kind on the base, and he says that the commanders wanted to see a sample prior to authorizing the project. “So, we picked one island in the parking lot and put it together so they could visually see the types of plants we were proposing,” says Flach. “Once we did that, the command approved it.”

The installation contract was awarded to KN Lawn Service, Inc., and employees of that company began removing the existing plants on April 1, 2008.

Flach says there are many xeriscape-compatible plants from which to choose, and that nurseries in Hawaii have made a big push over the past five years or so toward providing native and water-conserving plants. However, “the nurseries here are not huge, and because we needed almost 59,000 plants altogether, none of the nurseries had the quantities,” says Flach. Nurseries were contracted to grow the necessary quantities of each species, and it took nearly six months to get them to an acceptable size. “They worked very hard and met all of our deadlines,” he adds.

Because the mature trees in the islands were being left in place as the plantings below were changed-out, there was concern about minimizing the amount of soil disturbance. “We didn’t want to damage the roots, or the existing irrigation system,” says Flach. “We amended a little bit with rototilling, but mainly the plants would just be installed in individual holes. Even though a soil test showed that the soil was relatively fertile, because we didn’t do much amending, part of my job was to pick plants that would be adaptable to almost any kind of soil.”

The new xeriscape installation performs the important role of beautifying and “breaking up” the large asphalt parking lot, while also requiring less water and maintenance than the original plants.

The construction was completed in September and was followed by a four-month “maintenance period” to be sure the new plants were establishing well, that weeds were controlled and that the irrigation system was functioning properly. Weed control proved to be a challenge during this phase, but the contractor brought in a large group of employees who hand-weeded the entire installation. After that, problem weeds were spot-sprayed to avoid damaging the newly established xeriscape plants. “Now, because we’ve gotten beyond that initial period, we’re seeing very little weed pressure and growth is good,” says Flach.

One portion of the xeriscape received an inadvertent early test. When workers began removing the existing plants throughout the parking lot islands, they shut off the entire irrigation system, including the zone that provided water for the one island that had been planted as a sample xeriscape. “It was unplanned, but the water was off for six weeks and the plants were actually doing better—flowering and growing more—with the water off than they had with the water on. And, this was the middle of summer—it was as hot as it gets here,” says Flach. So, early indications are that the overall xeriscape installation has the potential to dramatically cut water use.

“All of our irrigation systems have water meters, so we can monitor water usage and track how much is being used monthly,” Flach explains. Once the xeriscape has been established (like all plants, it takes some time for these low-water-use plants to develop a root structure), he will perform a before-and-after comparison to determine how much water the new landscape has conserved. “On an average, we’re hoping to save about 462,000 gallons of water per month, or about 5,420,000 gallons per year—and that’s potable water,” he projects of reducing watering from three times per week to twice per week. In dollar terms, that’s a savings of over $10,000 per year, which could rise if watering can be reduced to one time per week.

This flower bed area was planted with foxtail asparagus. The palm trees were already in place from the original landscaping.

In addition, maintenance savings are expected. With the exception of one species, the groundcover plants chosen are not “runners,” nearly eliminating the need for edging and pruning. Also, because the native plants tend not to need as much fertilizer, that schedule might be cut from three times a year to once per year. Finally, because less watering will be needed, there should be less maintenance required on the irrigation system itself.

“This $500,000 project is more than cosmetic surgery,” says Scott Bonn, facility manager for NAVFAC Hawaii. “Through the use of native plants accustomed to Hawaii’s climate, the new landscaping will not only conserve water, but also reduce grounds maintenance costs. These annual savings will eventually pay for the entire project.”

As large as the installation was, it represents but one part of the overall Pearl Harbor NEX, so a second phase—similar in scope—to install xeriscape landscaping around and adjacent to the various buildings is on the drawing books and is projected to be approved by September 2009. The high-profile installations at Pearl Harbor have the power to spread the message about xeriscaping, as well. In addition to many positive reports from those visiting the facility, the Exchange is now selling many of the plants installed out in its parking lot.

“We sort of ‘schemed’ this location a little bit,” jokes Bonn. “We’d been talking about xeriscaping for reducing water use and maintenance for a while, but getting the funds for projects is always a challenge. And, nobody really understood what xeriscaping meant—they thought of ‘zero,’ as though there would be no plants. So, we picked the NEX location because it’s one of the highest profile locations for the military on the Island of Oahu. We thought it we could show it was a success here, there would be funds for other similar initiatives.”

That’s exactly what happened. The word has also spread through military publications and other means. “Xeriscaping is definitely being talked about a lot in the Navy right now,” says Flach, “and there’s been a lot of interest in the project here.”

Patrick White is a freelance writer and editor who has covered every aspect of the green industry in the past 13 years. He is based in Middlesex, Vt., and is always on the lookout for unusual stories.