Owner: Pennichuck Water Service Corporation

Partner: Kingsbury Companies

Type: Infrastructure Support

Location: Merrimack, New Hampshire

Project Description: For this project, H.B. Fleming installed three cofferdams on land for junction structure, as well as interconnected piping and a wet well. In the water we installed a trestle for crane access to the river and a 200-foot-long sheet pile cofferdam to allow for installation of the pipe.

Challenge: One of the technical challenges of this job was installing steel pipe—fitting the flanges and couplings—underwater. On top of which, the Merrimack River flooded a week before the completion date.

Solution: Working closely with our diving subcontractor, Pepperell Cove Marine, H.B. Fleming successfully installed all cofferdams, excavated the river cofferdam, drilled the micropiles in the river; installed all pipe; and attached the intake screen. The efficiency and expertise of the team helped us stay the course for on-time completion, despite the Merrimack’s 10-foot rise.