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Underwater Blasting Frequently Asked Questions

                                 50 FOOT HARBOR DEEPENING PROJECT -  FAQs

1. How does the U.S. Army Corps of Engineers (USACE) get involved in deepening channels?

The U.S. Army Corps of Engineers (USACE) is the U.S. Government lead agency in the development of water resources. In this role, Congress directs USACE through authorization and funding to study specific water resources problems, such as shipping channels, flood damage risk reduction and coastal storm damage risk reduction. USACE will first study the problem by conducting a Feasibility Study and then, if it finds that there is a project that will solve the problem, request authorization and funding to construct that project, in cooperation with a local cost-sharing partner.

2. Why are the shipping channels being deepened in the Harbor?

USACE has been involved in deepening channels in the Port of New York and New Jersey for over 100 years. A feasibility study was completed in 1999 that examined the potential need to deepen the navigation channels to the four main container marine terminals (South Brooklyn Marine Terminal, Global Marine Terminal, Port Newark/Elizabeth Marine Terminal and the New York Marine Terminal). The study concluded that deepening the channels to 50 feet below mean low water would provide safe and efficient passage for the largest container ships then known. In 2000, Congress authorized USACE to construct the recommended project and in 2005 USACE awarded its first of sixteen construction contracts to deepen the channels to 50 feet.

3. Why is drilling and underwater blasting necessary in the shipping channels?

In order to deepen a shipping channel, material such as bedrock, glacial till, sand and mud must be removed. Some areas of the channel floor are comprised of bedrock. Since bedrock is hard, an excavator, which resembles a very large backhoe, is first used to remove as much rock as possible. Once this is accomplished, the rock is broken up into small pieces for removal. To accomplish this, a series of small underwater explosions are set off to fracture the rock for removal by the excavator.

4. How will residents know if drilling and blasting operations will be performed nearby?

The USACE has established information outlets to keep the public informed about drilling and blasting activities. A public information session is held at a local site for residents who reside within 1500 feet of a precautionary zone prior to the commencement of drilling and blasting work.   Noise and vibration reports are posted on the USACE NY web site.  The dredging contractor also has a hotline in place (201) 339-6470.

5. What is the geographic extent of the drilling and blasting?

The current deepening contract for the 50 ft deepening project exists in three areas.  The primary and largest area is in the Arthur Kill Channel from the bend at Howland Hook to just north of the Goethals Bridge.  The second area is a 1,000 foot long area in the western portion of the Elizabeth channel.  The third and smallest area is at the U.S. Coast Guard Buoy #10 in the Kill Van Kull located just off of Mayor Dennis P. Collins Park, Bayonne, NJ.

6. What is a pre-blast inspection and how can one be scheduled?

Inspections are used to protect a structure owner and dredging contractor. Pre-blast property inspections are conducted free of charge for property owners and residents who request one. The pre-blast inspection is a process of recording pictures, digital images, video, and/or sketches the existing conditions of a structure to later compare with any structural damage they may have possibly been caused by the vibrations from underwater blasting.

7. Will I be notified if I should have a pre-blast inspection?

Yes. The subcontractor in charge of blasting operations has an obligation to notify every structure occupant within a 1,500-foot radius of the blasting activity. This is accomplished using several methods. The initial notification will be a door notice that will be attached to all doorknobs of residences and businesses within 1,500 feet. This notice describes pre-blast inspection opportunities available, and how to schedule an appointment. The second method will be the contractor sending a written request to schedule a pre-blast property inspection. This request will be sent by first class mail to all residents and property owners who reside within a 1,500 foot radius of the blasting activity. Finally, a second request for pre-blast property inspections is sent by certified mail to the same property owners and residents to ensure that the information is received. At any time, residents can contact the dredging contractor at (201) 339-6470 to schedule an appointment.

8. Will vibrations from drilling and blasting activities damage property?

USACE does not expect any home or business structure to be damaged from the underwater blasting.  There are federal, state and local government agencies that impose restrictions and laws pertaining to ground vibrations and air pressures from underwater blasting. These limits are based on extensive research conducted by many agencies and specialist throughout the world. One of the leading, and most restrictive, is the United States Bureau of Mines. USACE has chosen to use the most restrictive, which is designed to prevent damage to a historic structure located within 1,500 feet of the blast.

9. Are noise and vibration monitoring procedures implemented during blasting activities?

To ensure the safety to communities, residents, and structures in the project area and to minimize the level of disturbance that the project may cause, USACE uses the best available drilling and blasting technology, and adheres to all federal, state and local requirements. USACE and its subcontractors are aware of the concerns that are often associated with drilling and blasting operations in the Port of New York and New Jersey. To help keep damages from occurring during drilling and blasting, USACE monitors all blasting activities conducted by its subcontractors to ensure that vibration levels associated with each blast are within the allowable vibration limits that have been set for each project area. Portable seismographs are used to measure and record the ground vibrations and air overpressure. The specialist conducting this work will analyze the recordings and keep updated information available at all times for USACE, authorized agencies and concerned citizens to review. Blasting event reports are kept for each blast and contain information about the vibration level as it compares to the Table of Safe Blasting Levels established by the explosive industry.

10. Who should residents contact if there are concerns regarding drilling and blasting operation?

Residents and property owners who have concerns during the drilling and blasting activities may call the blasting sub-contractor - Contract Drilling and Blasting (CDD LLC) phone number (201) 339-6470. Residents and property owners name, telephone number, address, and nature of concern will be documented and reported to USACE within 24 hours. Within five calendar days, the subcontractor, along with a USACE Quality Assurance representative will visit the concerned resident or property owner to discuss/address specific concerns.

11. How does USACE follow up regarding concerns?

The subcontractor and USACE take concerns about damage assertions to any property during blasting operations seriously. Visits to residents and property owners logging concerns include documentation; observing a blast with the resident or property owner at his/her home or place of business; placing strain gauges on any cracks; and/or placing a geophone at the property to monitor vibrations, both of which will remain for the length of the project.

12. How will residents know if concerns are related to the blasting operation?

  • The first step is to either phone the dredgers hotline (201) 339-6470 or view the latest monitoring report on blasting vibrations. This will provide you with information as to whether a blast occurred on a certain day and recorded vibrations.
  • Letters acknowledging the date, time, location and what was done during the visit are mailed to the resident or property owner who logged the concern. When the blasting operations have been completed, and the contract is completed, the sub-contractor and a representative of USACE will conduct a final inspection of any alleged concerns.
  • The subcontractor will send out a final determination letter, which includes the assessment of any damage claim and the course of action, if any, that will be taken. USACE receives a copy of this letter and will notify property owners or residents in writing of their options should they disagree with the findings.