The city of New Haven, CT, is spending $4.5 million to replace its single-conduit underground water system with a new one that separates sewer water from drainage. One of the benefits of the replacement will be to save the city the expense of treating rain water.
Complete Construction Co. of Ansonia, CT, is placing approximately 20,000 ft. (6,096 m) of pipes under several blocks of 20 streets. Depending on usage, the pipes range in diameter from 24 to 36 in. (61 to 91 cm) and are being placed 22 ft. (6.7 m) below the road surface.
Downtown New Haven has sandy soil that must be shored up in order to excavate. Complete Construction began by digging down approximately 6 ft. (1.8 m) and laying 12- by 12-ft. (3.6 by 3.6 m) trench boxes. The trench boxes act as supporting framework for metal sheet piling driven along two sides of the boxes. Once the pilings are in place, work continues by excavating down through the trench boxes. As each section is completed, the boxes and sheet piling are removed and used on the next area.
At first, Complete Construction used a bucket to bang the piles into the sandy soil. This was slow going and damaged the bucket. Tim Germain of W.I. Clark Company, Wallingford, CT, provided the solution by supplying a Tramac 625SH vibro hammer on a Hitachi 330.
According to Tony Teixeira, president of Complete Construction, the task of driving and extracting piles became quicker and easier.
The 625SH vibro hammer is the largest of Tramac’s four models. The “SH,” for swivel head, refers to the tilt bracket that allows the hammer to rotate 90 degrees so its body is parallel to the ground, making it easy to clamp onto and lift sheet piling lying flat on the ground. Tramac’s vibro hammers are simple to install. They are equipped with a valve that allows them to operate from the excavator’s bucket circuit.
The New Haven job presents plenty of challenges, including busy streets, difficult access and plenty of underground utility wires. Because 20-ft. (6 m) sheets would have torn through wires, the sheets are being driven down in sections, deep enough to approach the wires but not interfere with them. Additional pile sheet sections are placed below the wires, then the upper and lower sections are pieced together.
(This article appears courtesy of Tramac’s “Breaking News.”)