NEW ORLEANS SEWER SYSTEM EVALUATION AND REHABILITATION PROGRAM SUCCESS THROUGH VISION AND INNOVATION
Abstract:The authors present a case study of the efforts underway to upgrade the sewer system in the City of New Orleans, Louisiana, under a capital improvement entitled the Sewer System Evaluation and Rehabilitation Program (SSERP). Unique aspects of the Program include: a heavy emphasis on the use of trenchless technology to minimize the impact in historic and critical areas of the city, a comprehensive and integrated web-based Geographic Information System (GIS) that is accessible to the public and the use of a Rehabilitation Decision Support System (RDSS) to automate and expedite the design process. The presentation of the case study shall include the Program's efforts to synergistically involve the entire engineering community through the use of multiple contracts and the significant involvement of disadvantaged business enterprises (DBE).
The Sewerage and Water Board (S&WB) of New Orleans is engaged in a multi-year 640+ million capital improvement program to evaluate and upgrade the City's sanitary sewer system. To oversee the Program, the S&WB selected MWH (Montgomery Watson Harza), a global leader in water and waste water engineering. New Orleans, home to approximately 500,000 residents, faces more than its share of unique problems. The City is ringed by levees, was settled predominately on marshland and for the most part lies below sea level. Differential ground settlement plays havoc with the aging sewer system and the splendid live oak trees that line many of the City's streets are no friend to the sewer system.
The SSERP was developed to study, design, construct and certify that the sewer system has been brought into compliance by the established milestone dates of a Federally mandated Consent Decree. With over 1300 miles of gravity sewers, 100 miles of force mains, 83 pumping stations and nearly 30,000 manholes in the system, the need for a detailed plan, meticulous documentation and the use of a GIS to track the progress is clearly evident. To date over 11,000 individual repairs to the system have been completed of the estimated 70,600 total repairs required.
New Orleans, like other mature urban environments, faces complex challenges to maintaining its aging sewer system. Open cut excavation in many locations is extremely difficult or not feasible because of conflicts with an assortment of utilities and other City assets or resources. To minimize Program costs and facilitate the work, the SSERP employs an array of trenchless technologies to complete sewer line replacements throughout the system but particularly in the City's historic French Quarter and bustling Central Business District (CBD). For sewer lines in reasonably good condition, cast-inplace liners allow for an excavation-less repair minimizing the impact on the streets and trees above.
Pipe bursting in the CBD is a rehabilitation strategy permitting the simultaneous replacement/upsizing of lines and the installation of a fiber optic housing network. This dual-purpose rehabilitation (DPR) comprehensively replaces the entire main line sewer while simultaneously installing fiber optic conduit that communications providers can lease. This new technology is being demonstrated in a pilot project and is accomplished by pipe bursting the existing sewer pipe and replacing it with fused high-density polyethylene (HDPE) pipe. The fiber optic housing conduits are pulled in place with the new pipe creating deeper conduits that offer greater reliability. It is expected that revenue from this fiber optic network will help minimize water and sewer user rates throughout the City.
Cast-in-place liners can save the S&WB up to 75 percent of the cost an excavated repair and avoids buried conflicts. Using this trenchless technique not only minimizes the disturbance on the surface but it eliminates the need for costly pavement, curb, sod and sidewalk restoration. Typically, restoration accounts for approximately 40 percent of the cost of an excavated repair.
With 1300 miles of sewer lines to be studied, defects identified, designed and repaired, the S&WB quickly recognized the need to mobilize the engineering and construction communities of the entire area, if the Program goals were to be met. Systems were developed in engineering, design and construction to assure 100 percent achievement of the 1000+ EPA milestones to be met over the 12-year period of the Program. Requirements to include DBE's in every aspect of the Program ensured that no sector was excluded. This innovative approach coupled with the use of the RDSS, an automated design tool, mobilized the community and brought about unity of purpose by teaming design and construction firms to accomplish the work in record time.
To meet Consent Decree Milestones established by the EPA, the SSERP, on a typical construction day, has between 300 and 600 active construction locations within City limits. Through the Program's public accessible web site (www.gosserp.com), citizens can view details of the Program activity down to the exact location of a construction contractor's crew working on a single manhole or sewer line segment on their street. This accessibility to information has reduced the number of residents submitting inquiries to the Program by an estimated 35 percent. Other City agencies, i.e. the Mayor's office, Director of Public Works and Department of Parks and Parkways also use the web portal to stay abreast of ongoing and upcoming work.
In conclusion, the paper will present details outlining the enormity of the Program and its success to date due in large part to the strategic vision of the New Orleans S&WB and MWH through the incorporation of several innovative concepts. The implementation of these unique approaches to the rehabilitation of the sewer system has resulted in an average reduction in the per linear foot cost to repair sewer lines from 229 to 214 or 7 percent. Trenchless technologies have helped to preserve the historic French Quarter and majestic live oak trees, minimized the impact on the Central Business District, and demonstrated the S&WB's desire to complete the rehabilitation efforts with minimum disruption while advancing the technological infrastructure of the City. The extensive use of the New Orleans area engineering and construction community has brought about a profession-wide sense of ownership and teamwork. And finally, the public is actively involved and can track the Program's progress through access to the web-based GIS. All of this is accomplished while meeting 100 percent of the milestones and being responsive to the EPA.
Document Type: Research Article
Publication date: 2005-01-01
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