Water Online

May 2017

Water Innovations gives Water and Wastewater Engineers and end-users a venue to find project solutions and source valuable product information. We aim to educate the engineering and operations community on important issues and trends.

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reduction in basement sewage backups, the occurrence of hydraulics-related sanitary SSOs, and interceptor surcharges; and • reduce infrastructure failures that contribute to combined sewer overflows (CSOs) and SSOs. The program included: • hydraulic condition assessment, data review, and modeling to understand the extent and nature of chronic problem areas • physical condition assessment, using CCTV, pole- mounted zoom camera inspections, and sanitary sewer evaluation technology • smoke testing and basement sump inspections to identify inflow contributions in each subbasin, subsequently used to develop a program to reduce illicit connections • sewer modeling to determine existing level of control and needed I/I removal requirements for regulatory compliance • maintenance and inspection program development. The rehabilitation and prioritization work helped identify, budget, and frame a capital plan for replacement, expansion, and clearwater elimination projects implemented in three phases over 15 years. As of 2017, much of the Phase 1 work is complete. Planning For Sewer Conveyance Damaged By Hurricanes In Florida Risk assessment has been critical for a sewer rehabilitation and replacement program for the Emerald Coast Utilities Authority (ECUA) in Florida. The system serves almost 300,000 people in Escambia County and the City of Pensacola, with 915 miles of gravity sewer and three wastewater treatment plants with a total combined permitted capacity of 33 MGD. Damage from Hurricane Ivan in 2004 had significantly increased I/I flows the years following. The risk assessment is helping to determine priorities and set the agenda for future work. To ground this comprehensive sewer rehabilitation program with actionable information, Arcadis conducted extensive data collection, including covered flow metering studies and sewer system evaluation surveys (SSESs) of 207 miles of gravity sewers in four major project areas. The flow metering included 12 long-term flow meters, four rain gauges, and 31 short-term meters. Smoke testing for cross connections and nighttime flow measurements using V-notch weirs to evaluate groundwater infiltration was completed in September 2009. A total of 1,500 manholes have been inspected to date. Initial CCTV investigations were completed in mid-2008. The hydraulic and physical condition assessments identified key areas of sewer rehabilitation needed for 21 miles of sewer damaged by hurricanes. Because this sector experienced the most serious problems with I/I flows in the service area, this rehabilitation construction work was completed first. Other work includes open-cut replacement of sewer mains and laterals as well as cured-in-place lining. Through investigative processes, it was found that in some areas more than half of the existing laterals were determined to be inactive and have been eliminated from the system, thus reducing both potential inflow and groundwater infiltration. Program tasks are accomplished through flow metering networks, nighttime weiring, above-grade storm inflow observations, smoke testing, and in-pipeline inspections using digital, state-of-the-art CCTV. The resulting information has been incorporated into the hydraulic model. As the program progresses, the entire service area will be prioritized for rehabilitation based on the size of the contribution of I/I, the anticipated failure period, and other criteria. A related phase of the project includes the evaluation of the condition and risk of failure of the force mains. Condition assessments such as transient pressure monitoring, in-pipe inspection, and other nondestructive techniques are being used to evaluate the current conditions and make recommendations regarding replacement needs. Risk-based planning brings down the total cost of sewer pipe rehabilitation and replacement. Integrating this work with asset management across the whole system for the complete asset life cycle will pay off many times over the years. But starting from a base of knowledge and using industry resources will help make the most of all needed risk assessment and possibly reduce the effort needed to identify critical weak points. The assessment then becomes a powerful data set to drive funding, planning, and execution. n wateronline.com n Water Innovations Condition assessment of a sewer force main using broadband electromag- netic technology to measure the pipe wall thickness Celine Hyer, senior vice president and conveyance lead at Arcadis North America, is a recognized expert in advanced rehabilitation and replacement planning for pipelines as well as treatment and pumping facilities, with over 17 years leading the implementation of asset management programs nationwide. About The Author ASSETMANAGEMENT 30

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