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Session 07B: Operations and Maintenance: Collection Systems
1:15pm - 2:45pm
Session Chair: Samantha Schreiner, WSC Inc.;
1:15pm - 2:00pm
Prescriptive Cleaning May be a Bitter Pill to Swallow but Some Municipalities are Finding a New Tech-Cure
ADS Environmental Services, United States of America;
Decade’s old prescription for maintenance1 is to aggressively clean. Grounded in sound logic, cleaning keeps sanitary sewers free of obstructions including FOG, roots, debris, and sediment which reduce capacity and create blockages.
Aggressive cleaning is effective for reducing SSOs2 but it is costly being labor intensive, requiring expensive vehicles and tools. Cleaning creates conflicting demands on finite maintenance resources, consequently, personnel and support infrastructure is strained.
Conventional cleaning practices are schedule-driven where frequency is based on historical occurrences. The consequence is over-cleaning, a wasteful consumption maintenance resources. It also promotes pre-mature pipe degradation due to high pressure sprays produces pipe wear leading to reduced asset life3. Safety is at issue with personnel sometimes required to work in high traffic locations.
Unquestionably, cleaning is an essential element of collection system operations and maintenance programs. Yet, the question arises, is there a way to reduce operations costs, slow asset degradation and lower safety risks while preserving or even lowering threats of SSOs?
The Cities of Renton, WA and La Mesa, CA independently asked this question looking a possible solution using monitoring technology. They postulated that real-time monitoring would provide continuous feedback at each remote site and they would clean as the monitors indicated to reduce cleaning frequency and acquire assurance against SSO
Pilot studies were implemented with advanced depth monitors at high frequency cleaning sites. Machine-to-machine cellular communications and software analytics and software tools were set-up to provide indications when to clean.
Renton’s four-month and La Mesa’s six-month pilots showed cleaning reductions of 94% and 80%, respectively. Pilot design, test data, costs and results will be detailed with hydrographs and data tables to illustrate findings.
Optimizing Operation, Maintenance, and Rehabilitation of Sanitary Sewer Collection Systems. Prepared by the New England Interstate Water Pollution Control Commission, December 2003.
Best Management Practices for Sanitary Sewer Overflow Reduction Strategies 2009_ 13Feb19, Central Valley Clean Water Association and the Bay Area Clean Water Agencies
Cavitation damage to potential sewer and drain pipe materials C.A. Fairfield n School of Engineering and Information Technology, Charles Darwin University, Darwin, NT0909 Australia
2:00pm - 2:45pm
DIY Injection Grouting For Municipal Manholes
Dean LeBret. Jr.
City of Sweet Home, United States of America;
Innovation is required to bridge the gap between crumbling infrastructure and the maintenance teams that keep it functioning. The City of Sweet Home, Oregon has a history of high I&I. After four very successful collection system rehabilitation projects reduced peak flows from 22MGD to 12MGD, City crews have now identified leaky manholes as one of the major sources of remaining I&I. The City needed a cost effective way to stop the leaks found in real time that would not involve a large capital outlay. Manhole rehabilitation solutions are expensive and usually involve hiring contractors with specialty equipment to repair manholes in batches. Purchasing a grout injector was also expensive and the equipment would be oversized for the City’s needs. There was a gap between the solution that was needed and the solutions that were available.
Maintenance staff got creative and converted a retired airless paint machine into a high pressure injection grouting machine, thereby producing a medium-scale, self-contained system for repairing leaks immediately upon discovery. The City found its bridge and has now launched an effective manhole stop-leak program at a fraction of the cost of contracting out. Staff will present how the machine was built, totally in house, with only a few new fittings. Staff will also discuss a few application techniques learned, our success with different grout types, and some of the best practices we learned along the way.