CONSTRUCTABILITY OF LARGE DIAMETER PIPELINES IN AN URBAN ENVIRONMENT: A CASE STUDY

摘要

The City of Baltimore (City), Maryland has recently undertaken an extensive program to upgrade and rehabilitate their aging sewer system. The City, whose aging infrastructure has led to the necessity to replace and upgrade their existing systems, is under an Administrative Consent Order (ACO) to bring their system into compliance with state and federal regulations and to cease polluting the Chesapeake Bay. As part of the ACO, the City is required to upgrade the force main servicing the New Jones Falls River Basin. The work to be performed includes, in part, upgrading the existing pump station, upgrading the gravity sewer, and replacing the existing 36" force main. The replacement of the 36" diameter force main requires the installation of 42", 48" and 54" Prestressed Concrete Cylinder Pipe through city streets at depths well in excess of 20 feet and, in some instances, in excess of 30 feet. In order to complete this upgrade, the pipelines that are required to provide the City with sewer services are both larger in diameter and more difficult to construct than the existing ones. What is more, the presence of existing utilities makes it more difficult for engineers to find non-conflicting routes for the new pipelines. As a result, the new pipe lines are requiring extensive relocation of existing utilities; they are being constructed deeper and are becoming more costly to the owner. This paper will follow the New Jones Falls Force Main Project through the following phases: Design; Bidding; and Construction; with the main emphasis on the Construction Phase.