Water World: Connect to conserve

April 12, 2021 - By Abby Hart

Company: Ruppert Landscape
Location: Washington, D.C.

Occupying the last available space on the National Mall, the Smithsonian’s National Museum of African American History and Culture (NMAAHC) was completed in spring 2016. Ruppert Landscape’s scope of work for this project included landscape, irrigation, soils, site amenities, stone curb, concrete flatwork, concrete walls, pavers and water features. Ruppert handles the mowing for the site while in-house teams maintain the irrigation, landscape and turf.

Adjacent to the landscape elements, 16,000 linear feet of drip irrigation and 4,000 square feet of spray irrigation were installed. Michael Guetig, irrigation specialist for the Smithsonian, says the irrigation system and the NMAAHC weather station, are tied into a Rain Bird Maxicom central control system.

NMAAHC’s irrigation system is connected to a water harvesting system. The museum’s site is one of the lowest in D.C., so a 70-foot deep hole had to be made watertight before the building could go up. The dewatering pumps collect the groundwater, send it to a 65,000-gallon cistern, which then feeds a system that regulates the water’s pH, filters it and treats it with ultraviolet light. It then goes into a 15,000-gallon tank to be used for irrigation and in the museum’s toilets.

The project earned Ruppert Landscape a Grand Award from the National Association of Landscape Professionals’ Awards of Excellence program.

Photo: Ruppert Landscape

The landscape design for the National Museum of African American History and Culture integrates the museum into the larger footprint of the National Mall, encouraging visitors to extend the museum experience outside and to linger and reflect on the important narratives being told within.

Photo: Ruppert Landscape

With limited staging areas on-site and the volume of work and various trades, materials that couldn’t be scheduled as just-in-time deliveries and immediately installed were often moved several times as staging areas became active work areas.

Photo: Michael Barnes

These 400,000 crocus bulbs were planted nearly a year ahead of the project’s opening date to help signify hope and optimism at the end of winter. Sourcing that number of bulbs — which came from the Netherlands — was a challenge for purchasers. It took approximately 10 crew members nearly five weeks to properly space and install them.

Photo: Ruppert Landscape

A two-man crew used a specially created lattice tool as a guide to evenly spray paint holes for approval by the landscape architect. Then, a six-man crew used 1.5-inch spade bits to bore through the sod into the soil with a third crew following behind on hands and knees to place three bulbs per hole at 9 inches on center. Adjustments had to be made along the way in areas where soil had settled below the turf, requiring corrections to grade before the bulb installation could be completed.

Irrigation project at NMAAHC (Photo: Ruppert Landscape)

Hundreds of man-hours were expended using laser levels to ensure precise grading and installation of hardscape, walls and walkways. Planning and replanning were crucial to avoid lost time on this project and to ensure its successful outcome.

Photo: Ruppert Landscape

There was a lot of planning that went into the installation of the irrigation system. All the hardscape, surfaces, walls, footings and subslabs, sleeves and penetrations had to be completed with pinpoint accuracy to ensure pass through of the irrigation lines to ultimately reach all the planting beds. The Maxicom system, which ties into the National Oceanic and Atmospheric Administration system used for the National Mall, consists of 905 spray heads and 35 zones — all of which can be controlled remotely.

Photo: Ruppert Landscape

Ruppert Landscape was responsible for the fountain base, which required close coordination with the fountain contractor. Numerous shop drawings, submittals and requests for information were all managed, coordinated and expedited to address the exact tolerances necessary to ensure that the dimensional stone fountain and drains worked symbiotically to produce a one-of-a-kind product. More than 220 yards of concrete were delivered to the area via a concrete pump truck to create the base, troughs and walls.

Photo: Ruppert Landscape

The general contractor, design team, landscape contractor, architect, Smithsonian Foundation and numerous D.C. agencies worked to solve problems and move the project forward to meet the open date.

Photo: Ruppert Landscape

The nearly 100 trees on the site are clustered in informal groups of shade and understory trees. The building’s west side, pictured here, embodies strong tree character with a mix of shade trees and cherry trees to begin the transition to the lighter character of the building’s south side. This side also ties to the understory tree palette of the Washington Monument grounds, which are adjacent.

Photo: Ruppert Landscape

Curved radius walls had to have precise 2-inch tolerances in order for there to be a small air gap that allowed for the expansion and contraction once the granite veneer was installed over top. Coordination between site personnel and the granite vendor with shop drawings, inspections and triple checking of everything before, during and after the pours were essential to achieve the finished product.

Photo: Ruppert Landscape

More than 95,000 square feet of concrete walkways and subslabs were installed. They include colored concrete and exposed pea gravel aggregate. A concrete pump truck was used to deliver material in hard-to-access areas.

Photo: Ruppert Landscape

There were 2,200 linear feet of split-faced granite curb installed on this site. Standard curbs in D.C. are specified as Mount Airy granite, which is harvested from a quarry in North Carolina and shipped several hundred miles to the site.

Photo: Ruppert Landscape

Ten thousand square feet of pavers crisscross the site, often juxtaposed against colored concrete, turf and exposed aggregate to provide visual interest.

Photo: Ruppert Landscape

Five hundred truckloads of gravel, 625 truckloads of soil, 15 tractor-trailer loads of plant material (including trees) and 92 loads of concrete were delivered, and 52 loads of debris/soil were hauled off of the site in 10 months.

Photo: Ruppert Landscape

Great partnerships, strong communication and resources to work through the details — often out of sequence and out of flow — helped mitigate and eliminate delays that could have taken place, ultimately bringing this much-awaited museum to fruition for future generations to enjoy.