Challenge
The Gulf Oil facility in New Haven needed to replace some old wooden dolphins used to moor their barges when transferring oil.
Solution
As part of the ferry design, GZA was subcontracted in 2016 by TPA Design Group. GZA’s coastal engineers performed a metocean analysis to evaluate wind, wave, storm surge, and anticipated sea level rise at the Site and prepared a high-resolution numerical wave and current model. The models were used to prepare environmental loading conditions for the terminal based on the 100-year flood event. The GZA design team accounted for an approximate 13-foot tidal zone design basis and compliance with Americans with Disabilities Act (ADA) site access requirements. The finished grade of the terminal and adjacent decking will be raised to elevation 13.0 ft NAVD to place the facility above the base flood elevation. GZA prepared mooring and berthing calculations and worked closely with the client and ferry operator to optimize the layout of the facility. Due to the large tidal fluctuations at the Site and operational requirements, GZA designed a floating dock system consisting of two pile supported fixed concrete landings connected by aluminum walkways, a 30-foot by 30-foot floating landing platform, 2,000 square feet of floating docks featuring bow-loading fender systems and loading ramps, two 60-foot long aluminum gangways, and two 100-foot long floating fender rails to assist in the safe and efficient berthing of the vessels. The subsurface conditions generally consisted of up to 20 feet of organic silt, up to 9 feet of estuarine deposits, 3 feet of glacial till, and bedrock. The floating dock guide piles were designed for an unbraced length (length of pile between the soils and the 100-year storm elevation) of up to 40 feet, and consisted of 24-inch diameter steel pipe piles rock-socketed into bedrock and filled with concrete.
Benefit
As part of GZA’s scope of work, GZA prepared plans and specifications for the fixed platforms, floating docks, foundation piles, aluminum gangways, and fenders. The Terminal design is currently ongoing and under review by the environmental permitting agencies.
