Merrick's Hydrolazing and Waterblasting took part in the "Big Dig," Boston's now famous $10.8 billion project. Merrick's is among the dozens of firms participating in what is formally known as the Central Artery/Tunnel Project. The Big Dig is a massive effort to reshape the way and manner in which Bostonians commute to and from work and alleviate the city's traffic problems.

The Big Dig includes the extension of Interstate 90 (the Massachusetts Turnpike) from its current terminus south of downtown Boston under Boston Harbor to Logan International Airport and the replacement of I-93 through downtown Boston, including a tunnel through the heart of the city.

Merrick's was assisting with the preparation of the concrete caissons or fittings on which pre-built sections of highway tunnel will be placed by floating them into position. Too much concrete was poured in certain areas and, in order for the tunnel segments to fit, the excess had to be waterblasted.

The job consisted of using a series of large pumps that shoot water from nozzles at a pressure of 20,000 pounds per square inch (PSI). Such high water pressures meant a person on land would not be able to hold the hose and nozzle. Instead, divers had to blast the concrete from 65 feet under water in order to avoid becoming fatigued from the heavy equipment.

A squad of divers handled the underwater work while John Merrick worked with the divers to fine tune the equipment to fit the requirements of the moment.

For more information on The Big Dig, see the outstanding official site.