Construction activities may impact the structural integrity of the adjacent existing structures during certain phases of new construction or renovations. Examples of these activities include but are not limited to Demolition, Support of Excavation (SOE), underpinning, Pile Driving/Drilling, Dynamic Compaction, rock Chipping/Hammering and Rock Blasting. Without a construction monitoring plan, activities such as the above can affect structures in many ways such as cracks to the adjacent structure foundations, causing structure damage and/or failure.
The Big Apple Group offers services to assist with the protection of adjacent structures. Our services can monitor for allowable thresholds and aid in understanding potential causes and provide possible solutions to a site's particular situation. The Big Apple Group has provided these services for numerous projects and work with the client to find appropriate solutions. We can provide quick and direct feedback of vibration levels to allow immediate adjustment and control over construction methods and procedures.
Protecting Adjoining Properties
Adjacent, or adjoining, property protection is a necessity nowadays with continuous frivolous lawsuits impeding millions of dollars of construction work daily. The Big Apple Group is able to analyze your project and its surroundings and assist in generating the most efficient possible protection plans and measures that should be taken to not only protect your best interests, but the interests of your neighbors.
Section BC 3309 of the 2014 New York City Building Code (NYCBC) outlines the requirements for protection of adjoining buildings and property from damage during construction, structural demolition, and excavation activities. Section BC 3309 requires preconstruction condition documentation and monitoring of adjacent structures with below grade excavations beyond a depth of five feet. In addition, BC 3309 references New York City Department of Buildings Technical Policy and Procedure Notice #10/88 (TPPN 10/88) which outlines the documentation and monitoring requirements for adjacent structures located within Landmarks Preservation Commission (LPC) designated Historic Districts. TPPN 10/88 provides for monitoring of Landmark or Historic District buildings within 90 feet of any site with foundation construction or earthwork excavation.
Monitoring Requirements (NYC)
In order to help your construction project comply Chapter 18, Section 1814.3 of the New York City Building Code; The Big Apple Group will be with you every step of the way. When excavation, foundation construction, or underpinning is required, adjacent structures and properties shall be monitored in accordance with a plan prepared by the Big Apple Group. We develop the scope of the monitoring protocol, including location and type of instruments, frequency and duration of readings, and permissible movement and vibration criteria. Our Monitoring Protocol takes into account the structures or property to be monitored and the conditions thereof, and include necessary actions to address exceedances.
As per Chapter 33, Section 3309.4.4 of the New York City Building Code; Monitoring is required during the course of excavation work the Buildings that are within a distance from the edge of excavation that is equal to or less than the maximum depth of the excavation and historic structures that are contiguous or within a lateral distance of 90 feet from the edge of the lot where an excavation is occurring.
Existing Condition Inspection & Monitoring
Pre/Post Construction Survey
The Big Apple Group offers complete Pre-Construction Conditions Inspections prior to construction/demolition. This inspection documents the existing conditions of the adjacent structures surrounding your project, reducing exposure to lawsuits arising our of perceived damages caused by construction activity. Additionally, the Big Apple Group offers Post-Construction Condition Inspection comparing the current conditions to those documented during the Pre-Construction Condition Inspection.
Vibration Monitoring is performed by documenting ground borne vibrations during construction. This type of monitoring helps protects the adjacent structure from exceeding the pre-determined vibration limitations and assists the contractor with mitigating their activity to reduce vibrations. Big Apple offers two forms of monitoring:
Remote Vibration Monitoring: Technicians installed programmed portable seismographs to continuously measure and record vibration activity during the workday. The data is uploaded to a server daily. Alerts via email are sent if a vibration is detected above limits, in real time.
On-Site Vibration Monitoring: Technicians install portable seismograph and monitor the site daily (in person) for on-site analysis and notification of the data collected. Crack Monitoring Big Apple has the capabilities to install both Manual and Remote Crack Monitors. These systems are used to monitor any movement of existing cracks or newly developed cracks.
Big Apple provides both Manual and Remote Noise Monitoring. The system is equipped with advanced sound level meters and real-time analyzing to existing background levels for noise (conducted prior to the start of work). The results will be used to establish a baseline of existing conditions. Noise Monitoring is also performed during construction activity to ensure noise levels do not exceed specified requirements.
Big Apple also provides optical monitoring and comprehensive reporting to track structural movement horizontally and vertically during construction activities. Points are set along various locations at the perimeter of the site, a baseline is established, and measurements are gathered as an indicator of settlement.
“Telltales” also known as crack gauges are installed and monitored on any open joints in the permanent structures on neighboring properties in locations specified by client and the engineer on record (EOR). The gauges are clear plastic that measure 1-inch tall by 6-inches long and come in two halves. The two halves are secured using epoxy glue or a direct fastener on opposite sides of an existing crack. The halves overlap such that they can detect relative movements that are measured to the nearest 1 mm on a graduated scale. Monitoring crack widths in concrete buildings, bridges, and roads is easy and reliable with Concrete Crack Monitors. Opening and closing and differential movement of the crack is continuously monitored.