Sound Blankets Get Pile Drivers Hammering Again
The Arlington County Water Pollution Control Plant in Arlington, Virginia is located on 35 acres of land in a residential / commercial neighborhood. The WPCP is a facility that treats 30 million gallons of wastewater daily from Arlington County residences and businesses and discharges cleaner water into the Potomac River and Chesapeake Bay.
Application Introduction
The plant staff has been working closely with the neighbors to improve the plant's image in the community. With the Potomac Yards project and new development in Alexandria, the Plant will soon have residential and commercial neighbors on all four sides.
Arlington County formed a "Master Plan Team" in 2001, which developed a long-range plan for major capital improvements to upgrade and expand the existing plant. As part of the plant upgrade, approximately 2,800 piles (a combination of auger cast reinforced concrete piles and long slender steel columns that are driven into the ground to support a vertical load) are going to be required to construct new buildings and structures at the WPCP.
From the planning stages the Master Plan Team knew this construction project was going to cause noise problems with the local residential / commercial neighbors. A large variety of equipment and construction work would be generating noise; the diesel pile driving was expected to cause the largest magnitude of intermittent noise. The two main sources of the noise from the diesel pile driving are the impact of the hammer on the pile and the vibrations from the pile into the air when it is struck.
The Master Plan Team had hired an acoustical engineering consultant to develop a noise mitigating solution. The initial plan was to build a berm shield around the area where the pile driving would be taking place as well as restrict work time from 7:00 AM to 7:00 PM and install a series of six noise monitors to continuously record noise levels.
These piles started being set into into place on 4/19/07, immediately construction was halted due to excessive noise levels in the surrounding neighborhood. The initial noise levels were 85.1 decibels with the berm shield wall in place the noise levels were 83.8, the levels were deemed excessive and a $238,000,000 construction project suddenly came to a halt.
Treatment Provided
The General Contractor on site immediately contacted Kevin McIver at Acoustical Solutions for a solution. A plan quickly formed to build a wall 107' long x 13' high out of AudioSeal Combination Blankets, Model #ABBC13-2, that consist of a 1" thick fiberglass absorber with a vinyl quilt that is stitched to a one pound per square foot sound blocker. Both the general contractor and Acoustical Solutions moved quickly to make this wall a reality and the sound blankets were manufactured with an expedite in just two days and shipped out to the jobsite and installed
Quantitative Results
On 4/25/07, just six days after the first pile was set, they were once again hammering away at an acceptable decibel level of 80.6. A couple weeks later they added a second sound barrier wall, again 107' long x 13' high further reducing the noise level down to 78.0 decibels.
Imagine what kind of costs are incurred daily with shutting down a $238,000,000 job. The General Contractor along with Arlington County were thrilled with the noise reduction levels achieved along with the speed at which this problem got resolved.
Later on in the project, additional sound blanket walls were provided on other parts of the property including a 215' long x 25' wall and additional shrouds for the drilling rigs.
As of February 19th, 2008, Phase 1 pile driving was completed! 2,252 driven piles were installed. Construction for the entire project is on time and is expected to be complete by January 1, 2012.
For more information on this application, contact our sales department.
