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Retail Establishment, Hooksett, NH

Retail Establishment, Hooksett, NH

A retail outlet had its expansion halted when it was determined that the new foundation would need a Support Of Earth (SOE) to install the deep foundation. NSI was selected to install a two legged shoring system. Once installation was begun shallow ledge conditions required internal bracing to support the SOE and retain the use of parking spaces above. NSI engineered and installed a temporary bracing that stabilized the SOE with sufficient strength to allow completion of the foundation.

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Public Boat Ramp, Mashpee MA

Public Boat Ramp, Mashpee MA

Reconstructed Boat Ramp Mashpee MA- In 2017 Mashpee MA awarded a contract to reconstruct an important town boat ramp. NSI was to hired to install a 60’ x 90’ x 60’ U-shaped cofferdam to permit sub-tidal concrete construction. The installation spanned 7 days and used 120 tons of sheet piles and 14 tons of steel bracing. The completed ramp was opened to general acclaim in early Spring 2018.

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Retaining Wall

Retaining Wall

NSI was called to Norwalk CT to the site of a new residence hotel near downtown. Temporary sheet piling was required for the construction of a permanent Redi-Rock wall along a busy roadway ramp. 30-40 foot steel sheets formed the wall in both braced and cantilevered sections.

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Foundation and Excavation Support, Medford MA

Foundation and Excavation Support, Medford MA

A local contractor called with a request. The high water table at this condominium site had stopped foundation work on the elevator shaft. He thought vinyl sheets would work but they failed to keep the excavation open. NSI installed 20’ steel sheet piles to solve the issue in quick order.

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Child’s River Boat Ramp, Falmouth MA

Child’s River Boat Ramp, Falmouth MA

NSI won a contract to set cofferdams for the reconstruction of a boat ramp on the Child River. The project involved constructing at U-shaped cofferdam, 70’x60’x70’. The cofferdam in place managed the tidal waters permitting the new ramp to be cast in the ‘dry’. The reconstructed ramp was open in early 2017 to a very pleased boating public.

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Underground Storage Tank Cofferdams

Underground Storage Tank Cofferdams

The NSI team has completed over 1,000 cofferdams for Underground Storage Tank (UST) installations. Each installation requires the erection of a bracing frame template to act as guide for sheet pile installation and to serve as formal bracing to keep the installed piles in place during the excavation.
Each project varies in complexity and engineering detail as exemplified in these photographs.

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Low’s Dam Rehabilitation

Low’s Dam Rehabilitation

Contract required a 100’ coffer dam of 25-30’ steel sheeting for the installation of a new spillgate and a water diversion channel in this 100 year old structure.

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New Water Intake Kelceytown Reservoir

New Water Intake Kelceytown Reservoir

NSI was contracted to build a 225 foot cofferdam using 25 foot sheet for the new intake. The 5 sided structure was constructed with a single level of steel beams. The contractor found the steel sheet wall was so well fitted that only minimal water pumping was needed to keep the excavation clear and dry for installation.

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Rehabilitation of Hovey Dam

Rehabilitation of Hovey Dam

In 2017 NSI’s team won the contract to rebuild of portion of the Hovey Dam along the Quinsigamond River in No. Grafton MA. A mid 19th century structure, the dam established a mill pond that once provided water power to a series of mills below the dam. As typical of old dams the original structure used the weight of the rock and mortar to build the walls. Over the past 170 years the mortar has dissolved and the rock structure was shifting. NSI constructed a cofferdam to isolate the spillway for reconstruction. The finished spillway stabilized a critical piece of infrastructure and extended the life of dam for years to come.

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Scituate Seawall

Scituate Seawall

In 2016 NSI was contracted by a local contractor to install 650 ft. of coated 25’ sheets as part of the reconstruction of a damaged seawall. NSI had drove the coated steel piles along the toe of the existing seawall to act as a foundation for a layer of heavy armor stone to protect the upgraded seawall. The highly compacted shore sand presented an intense driving challenge causing the edges of the new piles to glow cherry red with friction during insertion.

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