Mar 21, 201309:07 AMPoint of View

The METROPOLIS Blog

The Green Team Part 11: What Lies Beneath

The Green Team Part 11: What Lies Beneath

A tangled web of utilities is exposed during a recent streetscape project in Lower Manhattan.

Photo: Mathews Nielsen

Walking down a busy street, we rarely think about the interconnected series of stormwater pipes, train tunnels, electrical conduit, water lines, and tree roots that lie just inches beneath our feet—a “web of spaghetti,” as we call it. Typically, these common infrastructure components are out of sight and out of mind, yet they play a significant role in landscape design, particularly in urban settings.

In our previous post, POPS for the People…and the Developer, we described the benefits of privately owned public spaces (POPS) and the requirements associated with incorporating their designs into the city’s fabric. The New York City Department of Parks and Recreation (DPR) has published similar guidelines for streetscape plantings, including plant spacing as it relates to other built elements, infrastructure, and utilities. For example, a typical street tree pit would optimally be five feet by ten feet in size. The minimum horizontal distance from the edge of the tree pit as noted in the guidelines is four to six feet from any built obstruction (building, railing, stoop, etc.), three feet from a hydrant, five feet from a parking meter, and two feet from a gas or water valve. What happens when they prohibit any kind of planting or subsurface improvements? This was our challenge when planning future improvements for a small gathering space within Fox Square, a major crossroads in Brooklyn.

IMAGE TWO

Existing conditions of Fox Square.

Courtesy Mathews Nielsen

Fox Square proves the point we like to make: Some of the smallest sites can be the most challenging. At a mere 10,000 square feet, the site was selected for redevelopment as a part of the New York City Department of Transportation’s (NYCDOT) public plaza program in conjunction with the Downtown Brooklyn Partnership. Through community outreach and conversations with the New York City Economic Development Corporation (NYCEDC) and city agencies, it was determined that the primary goals of the redesign were to create a safe pedestrian environment by buffering them from existing traffic on Flatbush Avenue, discouraging jaywalking, and providing places to sit and gather.

Exiting the subway station for the 2 and 3 Lines at Nevins Street, you enter a vast open area at the crossroads of a busy intersection, paved in concrete and dotted with a few mobile food carts. This appears to be a great place to incorporate landscape improvements such as planting and seating and to create a refuge within the streetscape. What you do not see is the subway tunnel that lies just four feet below the surface and the maze of sewer lines that weave their way through the site amidst an active gas main and water line (see image below).

IMAGE THREE

Diagram showing existing utilities that move through the Fox Square site.

Courtesy Mathews Nielsen

Utility lines require offsets that must remain free and clear of obstructions, including trees and planting spaces. This, coupled with the fact that Metropolitan Transit Authority - New York City Transit (MTA-NYCT) regulates the subsurface space above its train lines (a minimum ten foot buffer between the top of their tunnel and the bottom of any planting area), can render subsurface improvements nearly impossible.

When we learned of these constraints during our Fox Square site analysis (we discussed the process in Property Lines: Invisible Identifiers of Ownership), we understood why there had been no previous plantings in the space. These planting zones were limited by existing utilities. So, we had to think of other ways to improve the space.

Microsoft PowerPoint - 2012.05.14_FoxSquare_Presentation

Diagram showing zones where trees can (white) and cannot (orange) be planted.

Courtesy Mathews Nielsen

Working with AKRF Engineering, P.C., we analyzed the site for areas that could be planted (see image above) and focused on such potential landscape improvements as enhanced paving and seating that would have minimal impact on subsurface conditions while activating the space.

After extensive coordination with city agencies, three shade trees were permitted in the design, on terra firma and within approved tree planting zones. Additional discussions with MTA-NYCT resulted in our placing smaller plant material, creating a planted buffer adjacent to Flatbush Avenue and Fulton Street. This solution  met a primary project goal of providing a buffer to traffic. Extending the streetscape palette of Flatbush Avenue was another way to activate the space while also meeting a key stakeholder goal--a place to sit and gather.

Microsoft PowerPoint - 2012.05.14_FoxSquare_Presentation.ppt

Proposed design for Fox Square

Courtesy Mathews Nielsen

Utilities are common players in streetscape projects located in urban plazas. In larger park settings such as Hunts Point Landing in the Bronx, for example, discussions with utility companies can result in the relocation of utilities--thus, the relocation of required utility offsets, as well—to provide additional green space. But within the urban realm, it is not always easy or fiscally possible to relocate utilities.

The next time you walk down a city street, take a moment to look down for manholes, valve boxes, and subway grates--ready clues to subsurface conditions beneath the urban hum. Then think about the “web of spaghetti” beneath your feet and the challenges that the landscape architect has to consider when imagining the open space above it.

In our next post, we’ll introduce you to more landscape interventions for challenging sites as we take you through a portable shipping container forest in the New York neighborhood of Hudson Square.

Lisa DuRussel, RLA, ASLA, LEED AP is a Midwestern transplant, avid coffee drinker, soils enthusiast, and practicing landscape architect in New York City. Since receiving her BS and MLA from the University of Michigan, she has worked on numerous urban revitalization and cultural landscape projects in the New York and Chicago areas, including the Governors Island Park and Public Space project. This is one in a series of Metropolis blogs written by members of Mathews Nielsen Landscape Architects’ Green Team, which focuses on research as the groundswell of effective landscape design and implementation. Addressing the design challenges the Green Team encounters and how it resolves them, the series shares the team’s research in response to project constraints and questions that emerge, revealing their solutions. Along the way, the team also shares its knowledge about plants, geography, stormwater, sustainability, materials, and more.

This is one in a series of Metropolis blogs written by members of Mathews Nielsen Landscape Architects’ Green Team, which focuses on research as the groundswell of effective landscape design and implementation. Addressing the design challenges the Green Team encounters and how it resolves them, the series shares the team’s research in response to project constraints and questions that emerge, revealing their solutions. Along the way, the team also shares its knowledge about plants, geography, stormwater, sustainability, materials, and more.

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