Best of 2009 Civil/Public Works Category

December 02, 2008

Agency: New York Construction Magazine
Project: Narragansett Bay Commission Combined Sewerage Overflow

McGraw Hill Publication’s New York Construction Magazine selected the Narragansett Bay Commission as its Best of 2009 in the Civil/Public Works Category. The Louis Berger Group, Inc. was the Program Manager/Lead Design Manager (PM) for the development of a comprehensive combined sewer overflow (CSO) abatement program. The program focused on the Cities of Providence, Pawtucket, and Central Falls, Rhode Island, the NBC CSO service area.

LBG completed a comprehensive Combined Sewer Overflow (CSO) Facilities Plan in 1993, which was approved by Rhode Island Department of Environmental Management (RIDEM) in 1994. In 1994, after submission of the plan, USEPA promulgated a new CSO policy that focused on water quality benefits and allowed either a "presumptive" approach or a "demonstration" approach to development of CSO control plans. NBC and LBG initiated a CSO reassessment to take advantage of this change in policy.

During the reevaluation process, LBG examined and formulated 16 new system alternatives. These system alternatives along with the originally proposed plan were evaluated using cost, environmental impacts, operational concerns and water quality improvements based on model data from design storm data. A stakeholder’s process was used to ensure widespread public involvement. The recommended plan consisted of a combination of technologies resulting in a cost reduction of approximately $170 million.

Phase I of the plan was a 16,000-foot long, 26-foot deep rock tunnel, with a 50MGD pump station at tunnel depth. There were seven drop shafts with connecting surface structures conveying flow to the tunnel, and a number of regulator modifications to enhance system operation.

 LBG divided the program into eleven construction contracts and was responsible for developing the bid packages and managing the bid process. Construction on the first contract started in May 2001; the final Phase 1 contract was completed in June 2007. LBG  also provided total program management of the construction process including construction oversight, and assisted the NBC on all administrative aspects of the program.