In 2003, the City of Nashville undertook a multi-million dollar renovation to its Metro Courthouse complex including a 5 level subterranean parking garage and “rooftop” public plaza. The total downtown site, consisting of approximately 7.5 acres, includes a 2.25-acre state-of-the-art intensive greenroof over the parking structure. A cornerstone of the design team’s concept was the establishment of a truly civic open space that embodies the term “Public Square”, providing unfettered access to all citizens to this civic hub from which a new pedestrian connectivity to the surrounding city could be realized. This new park not only complements the renovated 1930’s art-deco styled courthouse architecture, but accentuates its grandeur from all perspectives using rich, timeless materials that are also authentic within its contemporary design interpretation.

This in every way is “context sensitive” design. Predominant civic views and axes literally shape the design’s expression. At a more philosophical level, there is a subtle but important message sent by the broad civic lawn that stretches in front of the Davidson County Courthouse and Civic Building. From whatever point of entry, citizens reach the “level civic lawn” to stand equal in the sight of our elected government and court system.

Sensitivity to the stewardship of the environment, including water resources, is an integral part of the design. The challenge of a large 2.25 acre-sized impervious roof deck, the substrata of the park, is turned into an asset. Rainwater that falls on this area, as well as water from a garage sump, is harvested into a 57,000 gallon below-grade tank. Following filtration, this collected water supplies the required high-efficiency irrigation system with totally re-circulated water. Only in periods of drought is the tank topped-off by potable water. Due to this harvesting, it is necessary to employ a maintenance protocol that greatly reduces the use of chemical herbicides and pesticides — maintenance crews primarily utilize mechanical and organic weed and pest control.

The cost of the green roof averages approximately $30.00 per square foot, exclusive of the vertical circulation structures. The project utilizes Tremco’s hot applied, rubberized asphalt waterproofing membrane, TREMproof 150 HRA and lightweight aggregate (expanded slate), manufactured by The Carolina Stalite Company, incorporated into three different forms (lightweight aggregate, rooftop mix and firelane mix) for areas supporting different intensities of traffic. The depth of planting media varies from a minimum of 8” along the central ridge of the structure to a depth of five feet towards the edges. A diverse community of landscape materials is used, totaling 43 different species of which 81% are native to the SE region and 63% are native to Middle Tennessee.

The project re-incorporates many historically significant components from the original site. Some of those elements include reuse of granite units (wall caps, veneer, and steps), historical war commemorative monuments, and historical veteran plaques.  All installed granite walls, curbs, steps, etc. in closest proximity to the Courthouse terrace are constructed with the original granite.

The Nashville Public Square design re-invents what once was a polluting surface parking lot, and with the resolve of its community leaders, shapes a civic gathering space of dignity and circumstance. It recalls and interprets the historic stories of this location. It accommodates all citizens, offering a barrier-free entry from the surrounding street grid.  It turns the liability of a 2.25-acre impermeable subterranean five-story parking garage into an asset that harvests rainwater, conserving hundreds of thousands of gallons of potable water each year. …and it employs green roof technology to make all of this possible!