The scope of this contract was to design and install a 32 ft x 18 ft x approximately 20 foot deep steel sheeted cofferdam to act as a large siltation basin, in which the existing outfall pipes were to drain. Work also included locating the existing outfall pipes, excavation within the cofferdam, dewatering, characterization, transport and disposal of excavated material, construction of a concrete base slab and headwall, connection of the existing outfall pipes to the proposed cofferdam and removal of sediment debris from the end of the outfall pipes.
Numerous unforeseen subsurface obstructions, largely granite block and wood piles, were encountered during the prosecution of the work which required our proposed construction approach to be modified for the cofferdam installation as well as connection to the existing outfall pipes. Connection to the existing outfall pipe was required to be performed in the wet by divers instead of in the dry within a secondary cofferdam as originally proposed. This job for its size had more than its share of challenging situations.
All excavation, pile driving, carpentry and dive work was self performed by J.F. White.
Contract value: $744,000