The Hackensack Riverkeeper Green Roof Project

December 6, 2010

Today we continue our CUES guest blog series with a topic that’s near and dear to our hearts: a green roof project!

Roof of Hackensack Riverkeeper

Hackensack Riverkeeper roof

Hackensack Riverkeeper owns a headquarters building located in the middle of the highly urbanized City of Hackensack, NJ. When suburban families want to improve stormwater quality and reduce runoff from their property they can choose to install a Rain Garden. This Best Management Practice is great in suburban New Jersey where there is a lot of lawn, but downtown Hackensack is close to 100% covered by concrete sidewalks, roads, and buildings! So a different kind of solution is needed to manage Riverkeeper’s rooftop runoff. It is especially important to solve the runoff problem in older cities like Hackensack because the stormwater flows into the city’s Combined Sewer System (CSS). During heavy rains, the CSS discharges untreated sewage, along with stormwater, directly into the Hackensack River because the antiquated plumbing cannot handle the larger water volumes.

Urban areas across the U.S. (most notably Chicago) and North America have turned to utilizing green rooftops for their environmental benefits. While there are a few green roof installations in New Jersey, such as the Essex County Environmental Center in Roseland, we do not know of any urban areas in NJ that are currently using green roofs to diminish the impact of stormwater runoff. Hackensack Riverkeeper collaborated with CUES to determine the feasibility of converting their black tarpaper roof to a ‘Green Roof’. Undergraduates in the Departments of Landscape Architecture & Design and Environmental Sciences Studio Design courses at Rutgers School of Environmental & Biological Sciences (SEBS) accepted this challenge and designed a modular Green Roof system appropriate for installation on the Riverkeeper’s existing 1,500 sq. ft. flat roof.

Roof & ductwork of Hackensack Riverkeeper

Hackensack Riverkeeper roof

The benefits of installing a green roof have been known since ancient times (the Hanging Gardens of Babylon in present day Syria), and today green roofs are becoming an accepted building design feature, particularly in Europe where they may account for up to 14% of all flat roof systems. Environmental benefits of green roofs can include reduction in urban stormwater runoff and improvement in runoff water quality and plant uptake of carbon dioxide. Ecological benefits include an increase in urban habitat diversity. In highly urbanized areas such as those found in older NJ cities, up to one-third of the horizontal surface may be represented by rooftops. However, there are few green roof installations in NJ, and none in typical older urban downtown centers. There are no installations that we are aware of that might be duplicated inexpensively in privately owned, small to medium size buildings that make up much of the infrastructure of NJ’s urban landscape. Therefore, a demonstration Green Roof constructed on the Hackensack Riverkeeper building in the center of Hackensack, NJ (five blocks from the Bergen County seat) can show elected officials, building department staffs, and the general public an important tangible example of a sustainable construction option.

Captain Bill, Lisa Ryan, and Rich Dwyer from PSE&G went to New Brunswick to see the first 15 draft designs created by the students in the sophomore design studio class. They were joined by Dr. Christopher Obropta and his engineering students from the Department of Environmental Sciences. An example from the first design phase (conceptual plan) is shown here. While this illustration may not necessarily be the final form of the roof, it is the first step in determining a design that will achieve our stormwater goals, while having an aesthetic appeal that is representative of Hackensack Riverkeeper’s organization and mission.

Sketch of Hackensack Riverkeeper Roof

Schematic of Hackensack Riverkeeper Roof

The environmental engineering students then worked with the landscape students to develop plans for the final Hackensack Riverkeeper Urban Green Roof that PSE&G employees have volunteered to construct. It is particularly fitting that the roof will be built by PSE&G volunteers because the Hackensack Riverkeeper building was originally built by PSE&G as a regional substation – we are now coming full circle. The green roof installation will be done under the guidance of a certified green roof professional and Rutgers University Landscape Architecture & Design and Water Resources staff will test various vegetation combinations for their ability to reduce heat loss from the Riverkeeper roof. The Water Resources engineers and scientists will design a water collection system that can store rainwater for future use, and an easily maintained pumping system operated via solar power to move water from the collection system to the roof.

Roof AFTER Greening

Hackensack Riverkeeper green roof

The proposed Hackensack Riverkeeper green roof design is modular – it can be adapted for any size/shape structure, and so has broad applicability in older urban centers where there is a preponderance of available flat rooftops. This demonstration project will allow us to quantify actual energy and cost savings before and after implementation of the green roof, while introducing a design concept that utilizes readily available materials. The concept was designed with cost effectiveness as a critical component. This model demonstration project will allow other urban building owners in Bergen and adjacent Hudson Counties to see the energy saving benefits of a green roof installation and to easily adapt the concept for their own buildings. The energy and cost savings data generated by the pilot project will be disseminated through tours with elected and building code officials, description of the project on the Hackensack Riverkeeper and CUES websites, and via the quarterly Hackensack Riverkeeper newsletter, Tidelines.

Green Roof

The purpose of the Hackensack Riverkeeper Green Roof Project is to demonstrate that readily available, inexpensive components can be combined in a modular green roof system. Unless this technology can be demonstrated with ‘real-world’ local examples for building code officials, elected officials, the construction industry, and the general public to view, wide-spread acceptance of the green roof technology will not occur. Plus, the roof will provide a unique and exciting new vista for downtown Hackensack! CUES and Hackensack Riverkeeper have applied for funding to cover the cost of materials, engineering services, permit applications, and professional management of this project, and we hope to begin construction in spring 2011.

View additional conceptual plans for the Hackensack Riverkeeper Urban Green Roof.

Also, you can learn about the Dodge green roof and see photos of our garden here and here.

This guest blogger series will conclude next Monday.