Horizontal Directional Drilling Tunnel to Peddocks Island/Fort Andrews

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Environmental Partners was built on the core philosophy that a strict focus on client service through partnership creates added value for our clients.

What's New

Partnership

Environmental Partners was built on the core philosophy that a strict focus on client service through partnership creates added value for our clients.

What's New

Horizontal Directional Drilling Tunnel to Peddocks Island/Fort Andrews

Hull, Massachusetts

Overview

Peddocks Island, located between the coasts of Hull and Quincy, Massachusetts, is one of the largest and most ecologically diverse islands in Boston Harbor and is a key component of the Boston Harbor Islands National Park Area. Island Alliance is undertaking the restoration of the Fort Andrews portion of Peddocks Island to create a unique destination for Boston-area residents and visitors to the island. However, before the redevelopment of the fort complex could begin, reestablishment of utility service to the island was necessary. In 2003 the Island Alliance, with its project manager Jones Lang LaSalle, engaged Environmental Partners Group to prepare a feasibility study for restoration of utility services to the island. Environmental Partners was subsequently engaged to provide full design and construction-related services.

Approach

Environmental Partners executed a feasibility study which recommended that submarine water, sewer, power and communication connections be made across Hull Gut using horizontal directional drilling (HDD). Environmental Partners began design of the utility tunnel and connections in October 2004. The first significant design task was to complete a preliminary tunnel layout plan and gather geotechnical information on the channel crossing route. A jack-up barge was deployed to Hull Gut in mid-December 2004, at which time five deep borings were advanced across the 1,500-foot wide channel. The site stratigraphy consisted of sand, gravel and some till over argillite bedrock on the mainland, transitioning into nearly bare bedrock within the channel. On the island-side of the channel dense glacial till overlays bedrock.

In order to control project costs while providing for the island-specific utility needs described earlier, Environmental Partners recommended a single barrel tunnel design consisting of a 20-inch steel casing. Within the steel casing a bundle of high density polyethylene (HDPE) pipes would be installed, including a 6-inch water main, a double walled sewer force main (3” ID), primary power and communications conduits, and a pair of spare conduits.

Construction was conducted between May and November 2006 and was overseen by Environmental Partners. The HDD subcontractor was Michels Directional Crossings of Brownsville, Wisconsin. Overall, the project was completed two months ahead of schedule, free of change orders, and $20,000 below the base contract price.