BUILDING A LARGE DIAMETER DEEP SEWER PIPELINE UNDER URBAN CONSTRAINTS

摘要

Sacramento County in California has recently experienced significant growth in the northern portions of the service area.Growth, together with the aging sanitary sewer pipelines has caused the Sacramento County sewer pipeline system to become capacity constrained during wet weather events. To increase the sewer system capacity and service level, the Sacramento County's sewer agencies -Sacramento Regional County Sanitation District (SRCSD) and Sacramento Area Sewer District (SASD) - determined that a sanitary sewer relief pipeline was needed.The pipeline is located in a highly developed urban environment. Social, Economical, Environmental impacts and feasibility of Technology were the key issues that were considered during the project planning and design phase. The project team underwent a stringent process to evaluate different approaches.The evaluated approaches can be generally divided into two categories:1. Build pumping stations and forcemains and a gravity pipeline section2. Install a deep gravity sewerThe former approach would require shallow open trench construction while the latter approach would require deep open trench and high precision trenchless construction.This paper discusses:a) The reasons why trenchless technology was selected over shallow open trench construction approach;b) How trenchless technology contributes to not only the tangible economic factors, but also the intangible social factor, environmental factor as well as the agencies' public image; andc) How trenchless technology makes it possible to resolve conflicts among Social, Economical and Environmental constraints.