Green Construction Helps Clear the Air in Lower Manhattan

Lower Manhattan is an area of New York City smaller than 4 square kilometers, yet it is home to more than $20 billion in construction. This unprecedented redevelopment is a direct result of remarkable public and private investments in Lower Manhattan, specifically south of Canal Street, in the wake of the Sept. 11 World Trade Center (WTC) attack.

The rebuilding is aimed at transforming largely commercial Lower Manhattan neighborhoods into mixed-use residential, business and tourist destinations. That goal already has succeeded, as residential developers have converted mid-century towers into state-of-the-art homes and hotels (many of them “green”), schools are built, companies renew leases, parks expand and infrastructure is modernized.

The Lower Manhattan Construction Command Center (LMCCC) is helping coordinate this extraordinary rebuilding effort. LMCCC was created in 2005, when the governor and mayor of New York signed executive orders to help manage and mitigate the massive construction plans and projects that now already are improving Lower Manhattan — from the streetscape to the skyline.

Multiple federal agencies influenced the LMCCC's inception and purpose. Based on experiences of the Central Artery Tunnel Project (“The Big Dig”) in Boston, EPA and the Federal Transportation Authority (FTA), among others, understood from the onset that the anticipated amount of construction within a small, densely populated urban area was going to result in exposures to noise, dust, vibration, traffic congestion and related inconveniences.

Today, LMCCC is the agency that the community relies on to alleviate daily disruptions caused by construction. It does this in part through the environmental performance commitments (EPCs) to which developers are asked to comply — primarily those concerning noise, dust, vibration and traffic, though the list is comprehensive.

AIR QUALITY

The EPCs partly were based on EPA experiences during the Big Dig, and partly based on findings in New York's particulate matter (PM) toxicology over recent years. Concern over dust and emissions from the Twin Towers' collapse also factored into the EPC development. EPCs ensure that PM levels are consistent with the National Ambient Air Quality Act. However, LMCCC has done better than that.

In early 2010, the agency announced the reduction of overall air quality concentrations of PM 2.5 (emissions from construction vehicles) and PM 10 (dust particles from construction sites). These concentrations are below National Air Quality Standards and mark a downward trend that began 3.5 years ago, despite an unprecedented amount of construction.

The measurements continually are taken through a neighborhood-scale air quality monitoring program (AQMP), which includes continuous real-time monitoring from four fixed stations and mobile monitoring from river to river.

MONITORING & RESPONSE

While the program focuses on construction-related dust and emissions from construction sites, other source emissions also are evaluated. Restaurant exhausts, bus stations, boilers, power plants and other potential permitted sources may impact conditions. LMCCC agents also can compare long-term data records such as daily, weekly or monthly averages.

These stations send data to a restricted-access Web site to assess if elevated PM concentrations are from construction activities versus other sources, such as rush-hour traffic. The Web site database generates automated e-mail notifications of alarm conditions. Personnel then perform fence-line monitoring at construction sites upwind of monitoring stations that logged the alarms.

Personnel typically receive elevated concentrations alarms within minutes of, or during, the incident. This leads to prompt review of potential sources and whether construction activities may have contributed to the elevated readings (such as idling trucks, lack of dust suppression, absence of tracking pads and lack of tire washing).

This swift awareness of neighborhood environmental conditions aids enforcement of regulations, such as anti-idling laws and visible dust emissions. EPC enforcement also has helped define the LMCCC's role in guiding contractors through provisions for diesel-particulate filters and ultra low-sulfur fuel to reduce emissions coming from construction vehicles, from cranes and backhoes to ordinary generators and trucks.