Second Avenue Subway Construction
By Diane Reid
I’m president of my Upper East Side co-op, and we recently learned that the nearby Second Avenue Subway construction work will impinge on our building, even though our property was not part of the Metropolitan Transit Authority’s (MTA) original construction plan. The MTA has recently informed us that it will be digging underneath our property and that heavy machinery will be operated on the sidewalk and street in front of the building, closing off our main entrance. What should our building expect in the near future from the construction, and what precautions should we take to protect our co-op?
The Second Avenue Subway project has affected many properties along its path, and a number of owners have had to make permanent alterations to their building systems as a result. Even with the first phase of the new subway line planning to open in December 2016, the MTA is still notifying properties, such as your co-op, about changes in its plans for ongoing construction due to unforeseen conditions. Your building and the others will need to prepare for the construction to ensure your property is properly protected.
The impact that the construction work will have on your building will depend on many factors, such as the age of your building, its design, and the type of construction work being undertaken by the MTA.
There are, however, a number of steps your board should take to ensure that your co-op is adequately protected from the heavy construction and demolition planned next to and underneath your building.
Access Agreement
Before any work begins, your co-op’s legal counsel, with input from your engineer, should review the MTA’s access agreement. The access agreement identifies the extent of the easement rights the MTA will have to your property during and/or after construction work. Your attorney should make any necessary adjustments to the agreement, outlining stringent conditions and provisions, to ensure that your building is adequately protected before construction begins. For example, even though the MTA is waived from certain New York City Department of Buildings requirements, it is in the co-op’s best interest that the agreement requires DOB inspections and approvals to make sure the work has been performed properly and complies with code.
Structural Evaluation
For any kind of construction work being performed adjacent to an existing building, especially construction involving deep excavation such as with the Second Avenue Subway, it is critical to monitor the building throughout all stages of construction. The first step is for an engineer to conduct a pre-construction survey to document pre-existing building conditions. This survey serves as a record of the building’s overall baseline structural condition and can be used as evidence if any damage results from the construction.
The MTA’s own engineers will document the structural condition of your building as well, noting architectural and structural elements, utilities, and other design details. After the MTA develops its design, the general contractor will issue a schedule detailing the approximate timeframe for construction. This schedule will typically need to be modified over the project duration to reflect unforeseen circumstances.
Monitoring Techniques
For any kind of construction work being performed adjacent to an existing building, it is critical to monitor the building throughout all stages of construction.
Monitoring the effect that construction work has on adjacent buildings is critical in avoiding or minimizing damage. Movement tolerances should be established and carefully reviewed by structural and geotechnical engineers. Geotechnical monitoring will include soil boring overview and site observation during critical sub-surface work, such as excavation, pile driving, and blasting operations.
Several devices are used to monitor the effect of construction on adjacent buildings. Inclinometers enable engineers to see sub-surface movements during deep foundation work and whether it affects the incline of the building. Crack gauges, installed on existing cracks identified during the preconstruction survey, measure wall movement. Other monitoring devices that may be needed include vertical and horizontal tilt sensors, which are installed on the facade and also measure building movements. Seismographs, normally used to analyze seismic activities, may also be used to measure vibration and movement caused by blasting, pile work, or heavy construction.
Abatement and Demolition
Before construction, an abatement inspection must be conducted to test for any hazardous materials such as asbestos and lead. Older buildings will typically need to be subjected to abatement. Older building materials that often contain asbestos include pipe insulation and floor and ceiling tiles. Lead is often found in soils, paint, and steel fireproofing. Abatement of any hazardous materials must be done by a certified contactor under controlled conditions that meet all regulatory requirements.
Load Transfer
Underground construction often involves removing, replacing, or demolishing structural members, such as beams or columns. In a process known as shoring, temporary structural supports are installed until permanent structures are in place. For example, underpinning may be required below the basement to help prevent the building from settlement during excavation.
Shoring supports are removed as the building loads are transferred from temporary structures to permanent structures. Load transfer requires careful planning and must be monitored at all stages. The transfer should be so precise that residents do not notice any building movement.
Deep Foundations
If the soil or geological conditions below your building are poor, deep foundations may be needed for support during nearby excavation work. These support structures extend well below the surface soil to more stable earth or bedrock. The most common type of deep foundations are piles (poles), which require drilling to install. Pile driving often uses large quantities of water to enable deep drilling, so water pumps may be necessary to remove excess water and prevent it from undermining the existing foundation.
The time required for pile driving can vary from several weeks to several months, depending on the geological conditions. Because pile driving requires water pumping, exterminators should be retained to control vermin disturbed during drilling, and insects drawn to stagnant waters.
Utility Shutdowns
Utility shutdowns require efficient coordination between the building and construction teams. The MTA often requires temporary water-related bypasses to accommodate underground construction, which means multiple utility interruptions across a wide range of systems, such as sewage lines, domestic water lines, and electric and telecommunication systems. HVAC systems may also be affected, causing shutdowns. Steam line shutdowns should be conducted outside the heating season to minimize heat disruptions. .
Noise and Dust Protection
The MTA’s work will likely involve limited demolition of such areas as walls, floor slabs, and foundations. Demolition generates noise, which the access agreement should limit to a specific time period (ideally daytime) with specific decibel levels. Noise monitoring measuring devices should be installed in the building to insure that the decibel levels remain within the agreed-upon limits. Your building engineer will review this data for correlations between construction activities and allowable noise levels.
Residents should also be notified well in advance whenever blasting is scheduled. Your building engineer, property manager, and the board will want to work closely with an assigned community liaison, appointed by the MTA, to address residents’ concerns.
To limit the amount of dust infiltration into apartments, it is recommended that approved manufacturing filters be installed on air conditioning units. Heat traces may be needed to protect exposed pipes from freezing, and welding may require a fire watch.
Inspections and Warranties
The building owner will be subject to fines and penalties if inspections are not conducted on time.
Even if the MTA has pre-installed new mechanical or plumbing equipment in the building, annual inspections and tests are still required, including those for backflow preventers, sprinklers and standpipes, fire pumps, and emergency generators. The building owner will be subject to fines and penalties if inspections are not conducted on time. Keep in mind that warrantee periods begin once the equipment is installed and are not typically suspended during the MTA’s construction.
Blasting and Boring
Many buildings along the Second Avenue Subway line have been subject to underground blasting and/or boring. Blasting, in which explosives are detonated underground, creates loud noises and can cause buildings to shake.
Tunnel boring is sometimes used as an alternative to blasting. The tunnel-boring machine (known as “the mole”) is very difficult and expensive to transport, but it creates fewer disturbances than blasting.
Whether blasting or boring will be done near your property depends on your building’s location, the site conditions, geological material, and logistics. In either case, all of the precautions and measures described above apply.
With the MTA taking eminent domain over your property, your co-op faces a daunting road ahead. But with the right precautions and planning, you can insure the safety and protection of your building throughout construction and beyond.
Diane Reid is a Senior Project Manager at RAND Engineering & Architecture, DPC and an adjunct professor of civil engineering at the City University of New York. She has two decades of experience with heavy civil construction, architecture, and forensic engineering and oversees projects for RAND’s clients affected by the Second Avenue Subway construction.This column was originally published in the December 2015 issue of Habitat Magazine.