I/I Reduction Projects
The City of Oregon began work associated with the I/I Reduction Program in 2007. Here are some of the completed and ongoing projects associated with reducing I/I impacts:
GPS/GIS Sewer Network and Manhole Inspection/Maintenance
Beginning in 2007, the Department of Public Service started to inspect and tag sanitary and storm sewer manhole locations with a Geographic Positioning System (GPS). These locations were entered into the City’s Geographic Information System (GIS) database. Any faulty sanitary manholes or leaky sanitary manhole covers were noted and were added to a list for correction.
To date, the City has inspected and GPS collected over 5,500 structures in the sewer network. Corrections have been made over 200 manholes, and another set of manholes have been identified for a manhole lining project in the near future. Typical correction work includes raising low-lying manholes, changing manhole lids with holes to solid lids, replacing broken manhole castings, cleaning plugged manholes, and bolting lids shut. This work is ongoing.
Closed Circuit Television (CCTV) Sewer Inspection
The Street Department has been inspecting sanitary sewers via CCTV. This inspection includes checking for faulty and/or deteriorated pipes, pipe blockages, and broken lateral connections to homes. This work is part of an ongoing sewer maintenance program.
Jones and Henry Engineers Ltd. was hired by the City to perform sanitary sewer flow monitoring services during the fall of 2008 and spring/summer of 2009. Flow monitors were placed into the sanitary sewers in various locations and wet weather flows were compared with dry weather flows. Areas where the flows increased the most during wet weather are targets to reduce I/I.
Figure 2 from the Jones and Henry final report shows the effects of wet weather on the WWTP. This graph combines both the rain gauge data as well as the WWTP effluent (treated water discharging from the plant) to show how much stormwater actually flows into plant. This stormwater flow is then unnecessarily treated as wastewater at a high cost.
Jones and Henry, Final Flow Monitoring Report,Figure 2
The red and blue bars are the rain data in inches per day from both the Willow Cemetery and the Municipal Complex rain gauges. The pink line on the graph is the WWTP effluent leaving the plant. Immediately after rain events, the WWTP effluent skyrockets to levels far above the normal base flow of 4.0 million gallons per day(MGD). In the case of the mid April 2009 rain event (1.6 inchesin 24 hours) the flow rose to over 21 MGD, which is 5 times the normal base flow seen at the plant. That’s over 17 MGD in excess flow that the WWTP had to treat due to the rain event.
To view the final Flow Monitoring Report Executive Summary, click the following link:
These projects included the lining of sanitary sewers and connected manholes on Portland Street, Arthur Street, Wheeling Street, and Hayden Street from 2013 through 2015. Total project costs were $174,463.00.
In the fall of 2009 the City began a $740,000 sanitary sewer and manhole lining project that covered nearly 9,000 linear feet of sewer and 51 manholes. This project, known as Sanitary Sewer Rehabilitation Project Phase I, was funded through the Ohio Public Works Commission.
Rehabilitation work consisted of cleaning and video inspecting sanitary sewers and lining sewers that were leaking. Infiltration target areas, such as sewers running underneath creeks, were chosen to be part of this project. Also, 51 sanitary manholes were lined to prevent infiltration. Based on current influent data, the normal dry weather flow seen at the WWTP was reduced by approximately 500,000 gallons per day (GPD) following this project. This decrease was attributed to the elimination of groundwater infiltration into sewer pipes at creek crossings. A Phase II is planned in the near future.
From 2012 through 2013 the City constructed Phase 2 of the Sanitary Sewer Rehabilitation Project. With a cost of $2,337,289.00 this project included the complete replacement of sanitary sewers in the Cresceus Heights subdivision of the City. Over 9,650 linear feet of sanitary sewer was replaced within the City Right-of-Way (ROW) including private sanitary sewer laterals in the ROW. Storm sewers were also installed in the neighborhood. Sanitary sewer lining and manhole lining was also completed as part of this project on Wheeling Street and Pickle Road.
Starting in the Fall of 2015 SSR Phase 3 was constructed in the Euclid Park and Old Eastmoreland areas of the City. This project included the lining of 12,861 linear feet of Sanitary Sewer, 186 sanitary sewer laterals, and 56 sanitary sewer manholes in the City Right-of-Way. The project also included the excavation and repair of deteriorated sanitary sewer chimney risers along Wheeling Street and the lining of sanitary sewer crossovers underneath Wheeling Street. The final project cost was $1,776,066.53.
Starting in the Summer of 2016 SSR Phase 4, Part A will begin construction in the Ketcham’s Little Farms and Woodville Heights areas of the City along Woodville Road. This project includes the lining of sanitary sewers, laterals, and manholes and is estimated at $1,300,000.00.
Parts B and C will be along the Ketcham’s Home Gardens and Moundview areas of the City. Part B will begin construction in 2017 and Part C is planned for construction in 2018. These project will also be lining deteriorated sanitary sewers, laterals, and manholes in their respective project areas.
This project consisted of the rehabilitation of leaking/deteriorated sanitary sewer manholes via various trenchless repair technologies, including lining and chemical grouting. A total of 66 manholes were rehabilitated as part of this project. These manholes were discovered and prioritized during GPS inspections of the structures. This work was completed in Spring 2013 at a cost of $65,465.00.
An aggressive storm drainage improvement program has been implemented along with I/I reduction. Over 30,000 linear feet of creek/ditch bank have been debrushed and over 80 blockages have been removed to allow for better flows during rain events. All three major drainage systems (Wolf Creek, Otter Creek, Amolsch/Driftmeyer Ditch) have been surveyed for stormwater flow modeling and future drainage improvements. Modeling helps identify flow constraints such as inadequately sized bridges and road crossings. Preliminary design has also begun for relief storm sewers or overflow channels in these watersheds. Other designs are being implemented for smaller more localized flooding or drainage concerns.
Smoke Testing is used to detect stormwater inflow sources such as roof downspouts, driveway and yard drains, foundation drains, and stormwater drainage system cross connections. It can also detect structural deterioration and leaking joints in sewer pipes. Smoke testing is one of the most efficient and cost effective methods of locating sources of I/I within sewered areas.
Smoke testing has been completed in the majority of areas of the City with sanitary sewer predating 1970. These sewers were typically constructed of Vitrified Clay Pipe (VCP) and as these sewers age, they tend to deteriorate at pipe joints and lateral sewer connections. Results from both smoke testing and CCTV inspection have led to the Sanitary Sewer Rehabilitation (SSR) Projects that are currently being designed and implemented. Further smoke testing may be completed on an as needed basis to help guide future I/I reduction work.