Improved Inflow & Infiltration (I&I) Monitoring Program

Transcription

1 City of Abbotsford Improved Inflow & Infiltration (I&I) Monitoring Program Submission For 2009 UBCM Community Excellence Awards Best Practices

2 City of Abbotsford Improved Inflow & Infiltration (I&I) Monitoring Program Submission For 2009 UBCM Community Excellence Awards Best Practices Project Summary

3 Project Summary Inflow and Infiltration (I&I) are common problems seen in many municipalities. Aging infrastructure in sanitary sewer system adds a layer of complexity to the challenge. I&I can use up capacity in the sanitary sewer system which is designed for sanitary flow, and affects planning of capital programs. The City of Abbotsford improved its I&I Monitoring Program by installing permanent flow monitoring sites at strategic locations, refining its catchment areas, monitoring the real-time flow data via its SCADA System, and analyzing it using a webbased tool designed locally. As a result of an extensive database, accurate I&I rates are determined for the use of the City s Sewer Model, which can now accurately determine timing of capital upgrades. The tie-in of the City s Closed- Circuit Television (CCTV) program with the Improved I&I Monitoring program allows problematic areas to be assessed and pinpointed in a timely fashion. Repairs are often undertaken in a cost-effective approach, reducing the I&I going into the sanitary system and substantially increasing the expected service life and function of the infrastructure. For further information, please contact: Rob Isaac, Eng. L., Wastewater and Asset Engineering Manager City of Abbotsford South Fraser Way, Abbotsford, BC, V2T 1W7 Tel: (604) risaac@abbotsford.ca

4 City of Abbotsford Improved Inflow & Infiltration (I&I) Monitoring Program Submission For 2009 UBCM Community Excellence Awards Best Practices Summary Report (6-page with graphics)

5 Background Inflow and Infiltration (I&I) are common problems seen in many municipalities. Inflow is stormwater that enters into sanitary sewer systems at points of direct connection to the systems. These sources are typically improperly or illegally connected to the sanitary sewer system, can contribute a significant amount of water to the sanitary sewer system and use up capacity in the sanitary sewer system which is designed for sanitary sewage in the first place. Infiltration, on the other hand, is groundwater that enters the sanitary sewer systems through cracks and/or leaks in the pipes. Cracks or leaks in the pipes or manholes may be caused by age-related deterioration, loose joints, poor design, installation or maintenance errors, damage or root infiltration. Groundwater can enter these cracks or leaks wherever the sewer pipes lie under the groundwater table. The reduction and control of I&I in sanitary sewer systems should be considered with regard to a disciplined, long-term monitoring and maintenance program. The first step to resolving any I&I problems is determining how significant the problem is. Typically a sanitary sewer system evaluation is performed to assess the system. An evaluation of the sewer system will determine the quantity of inflow and infiltration, determine their sources and provide guidance to determine a cost effective corrective action plan. I&I Monitoring Program The City of Abbotsford owns and operates an extensive sanitary sewer system. The wastewater system services Abbotsford s urban development area, Sumas, and the Aldergrove area within the Township of Langley. The wastewater system generally flows from south to north to the JAMES Wastewater Treatment Plant. The wastewater system includes approximately 500 km of mains, ranging in size from 150 to 1800 mm diameter. The oldest sewer is approximately 47 years old and approximately 40% of the collection system is in place for more than 26 years. Because of its extensive system and gradually aging infrastructure, the City engaged the services of Kerr Wood Leidal (KWL) and initiated an I&I monitoring program since 2001 in the effort to pinpoint the problematic areas and include these problematic areas in the City s rehabilitation program. The monitoring programs conducted occurred during summer time (dry weather flow) and winter time (wet weather flow). The City was divided into 4 flow monitoring catchments. Data from flow monitoring were often received after the storm events. 1

6 An Improved I&I Monitoring Program Monitoring and Analysis of Real-Time Flow Data The I&I monitoring program has been ongoing since it started in The 2005/2006 I&I study refined the original catchments from 4 into a total of 14. These flow monitoring sites located in strategic areas and 7 out of 14 sites are permanent. (The rest of the sites are either temporary or semi-permanent, which has the potential to become a permanent site.) The number of monitoring sites continues to increase to date as the catchment areas are being refined. In 2009, the City is looking at adding 2 more permanent sites to add to a total of 9 permanent sites out of 16. The year of 2007 is when the monitoring of the real time flow data begins. The flow monitoring sites for the I&I study are tied with the City s SCADA system and real time flow data is monitored. The quality of the data is continued to increase due to technology advancement (broadcast via cellular network). These data are then analysed by Emerald (now called Flowworks), a web-based software developed by KWL. Emerald is also the winner of the Award of Merit in the 2007 Consultant Engineering of British Columbia (CEBC) Awards Gala. One of the initial findings of the improved I&I monitoring program is that the City s actual I&I rates are substantially higher than theoretical values previously used for design. This information is valuable for City s sewer and treatment plant capacity evaluations, ensures attention is given to reduce I&I so that the designed sewer capacity is preserved for sanitary flow, and eliminates any sewer upsizing capital upgrades that may be required because of the I&I problem. To enhance the City s ongoing I&I monitoring and analysis, the 2009 I&I Monitoring program includes the development of a real time flow monitoring display screen for use by the City. (Appendix 1) Accurate Data for City s Sewer Model In 2006, the City developed a sewer model using a commercial software H2OMAP Sewer (Figure 1). H 2 OMAP Sewer is a stand-alone GIS-based computer program for use in the planning, design, analysis, and expansion of sanitary collection systems. The program can used to model both dry-weather 2

7 and wet-weather flows and determine the most cost-effective and reliable method of wastewater collection. The City s Sewer Model includes development scenarios for existing land use and Official Community Plan (OCP) build-out populations. As with any other model development, the City s model will not give reliable results unless it is well-calibrated with field data. With the improved I&I monitoring program, accurate I&I rates are now developed, obtained, and entered into the model. Accurate I&I data increase the level of confidence of the model results. Figure 1 - City s H2OMAP Sewer Model Accurate Timing of Future Upgrades The City intends to update its Wastewater Master Plan every 5 years. The Wastewater System Master Plan is the basis for updating and funding the 25- Year Capital Works Program for the City s sanitary sewer system and the Development Cost Charge Bylaw. The development of the Wastewater Master Plan requires the use of the City s Sewer Model. Without accurate I&I rates, the City s sanitary base flow estimation can be skewed and thus affecting the projected future flows. This affects the accuracy of the planning of the capital projects. With accurate I&I data, the level of confidence in the Sewer Model results and projected future flows is increased. A more accurate timing for each capital project can also be planned and determined for adoption in the Master Plan. 3

8 Tie-in with CCTV Program Aside from the I&I monitoring program, the City also implemented a program to inspect and rehabilitate the sanitary sewer system. This program includes cleaning the sewers, inspection with a Closed-Circuit Television (CCTV) camera, and the coding and assessment of defects. Certain defects in the sewer system, such as cracks, fractures and holes, can be repaired cost-effectively with Cured In Place Pipe (CIPP) point repairs. The CIPP method involves the winching of a polymer resin saturated felt sleeve through the host pipe to the exact location where the defect was identified by CCTV. The sleeve is then inflated to take on the shape of the inside of the defective host pipe and the resin is cured under a specified temperature. Once complete this sleeve effectively seals the defective section and reinstates the structural strength for the original pipe. These repairs are cost-effective, and substantially increase the expected service life and function of the infrastructure. Until 2007, the CCTV was not directly linked to the I&I data. Following a recommendation from the I&I study in 2006, the City further integrated the CCTV inspection program to the I&I study and to inspect and monitor high flow areas identified in the I&I study. In addition to the CCTV camera, the City now also uses the side-scan sonar technology to inspect sewer. The sonar technology allows the City to evaluate major structural and operational condition of the sewer below water level. Inspecting sewer condition below water level when the pipe is live was not cost-effective, or in some cases not feasible, before the sonar technology comes on board. More information about the CCTV and the sonar technology is presented in Appendix 2. With the tie-in of the CCTV program to the I&I monitoring program, points of defects in the sewer system can be determined and repaired. Also, deformation of pipe sewers will occur when the pipe has cracked and the soil at the sides no longer provides adequate support. This can eventually lead to final collapse of the pipe if the cracks are not repaired. CCTV/Sonar inspection increases the expected service life of the infrastructure, reduces I&I entering in the sanitary sewer system, and defers asset replacement and capital upgrade needs. 4

9 Benefits The City of Abbotsford s Improved I&I Monitoring program demonstrates excellence by providing the following benefits, in addition to those discussed above: o Improved efficiency, productivity and cost-effectiveness Real-time flow data measured at permanent and strategic flow monitoring sites are now monitored through City s SCADA system and analysed using Emerald (Flowworks), a web-based analysis tool developed by KWL. In this improved program, the City no longer needs to wait for 6 months to collect temporary flow monitoring data for its use and analysis. This fast-track process improves efficiency and productivity of the City in terms of assessing and pinpointing problematic areas in the sanitary sewer system, and thus giving necessary attention, prioritizing and focusing its effort to these areas. The cost of I&I monitoring is minimal as compared to the cost of asset replacement and/or sewer upsizing due to an I&I problem. With the tie-in of the CCTV program with the I&I monitoring program, defects in the system susceptible to I&I can be pinpointed, assessed and repaired with a costeffective solution. o Solutions Applicable and Transferrable to other UBCM members I&I is an ongoing challenge faced by many municipalities nowadays. Aging infrastructure adds to the complexity of the challenge. The improved I&I monitoring program of City of Abbotsford is an example that is applicable and can be transferred to other UBCM members. o Improved public accountability and awareness of local government One of the main improvements in the present I&I Monitoring program is the ability to receive real-time flow data. Flow data includes sanitary flow as well as Inflow/Infiltration. With the data, the City will not only be able to determine accurate I&I rates, but also have a better handle on sanitary flow rates. Better flow data will allow the City to determine the upgrade timing of pipe, based on peak day flow rates plus maximum I&I rates. On that front, the City has recently participated in the National Drinking Water week by showcasing its toilet rebate program to the public. Aside from that initiative, public are encouraged to conserve water to reduce the water use at the source, which will also reduce the discharge to the sanitary sewer system and the treatment plant. 5

10 Currently all properties have universal water meters read on an annual basis. The City plans on upgrading to radio read meters which will allow meters to be read daily to determine high consumption rates (e.g. leak detection). Summary The City s Improved I&I monitoring program provides valuable maintenance and planning information. The I&I information helps the City effectively target preventative rehabilitation work, which reduces future capital and operational expenditures for the pro-active maintenance of the sanitary sewer system. The yearly I&I reports allow the City to update their sewer model with realistic I&I rates and increase the accuracy of the model results for the planning of future capital programs. Tie-in of CCTV program with the I&I monitoring program ensures problematic area is pinpointed and necessary attention is given to provide timely repair. As a result, asset replacement and sewer upsizing cost due to I&I problems are deferred or eliminated. The Improved I&I monitoring demonstrates City s commitment to provide a sustainable environment to its community, its Proactiveness to improve the current situation, and its Excellence to provide its residents a livable and affordable place to work, live and play. 6

11 City of Abbotsford Improved Inflow & Infiltration (I&I) Monitoring Program Submission For 2009 UBCM Community Excellence Awards Best Practices Appendices

12 APPENDIX 1 REAL-TIME FLOW MONITORING DISPLAY SCREEN

13

14 APPENDIX 2 CCTV / SIDE-SCAN SONAR TECHNOLOGIES

15 The City of Abbotsford Contract # Digital CCTV and Sonar Inspection The following cross-sections are supplied in digital form under separate cover for each link. Longitudinal view of pipeline showing water level, debris and bottom of pipe. Green line denotes water level Red Line denotes debris. Blue line denotes bottom of pipe. AquaCoustic Remote Technologies Inc., Vancouver, BC, Phone: (604) Fax: (604) Toll free :(888) Web page: 15

16 The City of Abbotsford Contract # Digital CCTV and Sonar Inspection Photographs This photograph shows the control trailer with the 1,646 m (5,400 feet) of electro fiber optic cable. The computer section of the control trailer. 18 to 1 optical zoom on the pan and tilt camera. The camera zoomed to the downstream manhole 114 meters away to gauge the extent of the floating debris. AquaCoustic Remote Technologies Inc., Vancouver, BC, Phone: (604) Fax: (604) Toll free :(888) subsea@uniserve.com Web page: 20

17 The City of Abbotsford Contract # Digital CCTV and Sonar Inspection Photographs Some of the ragging encountered on this survey. One of the long range setups, note the control trailer at the centre of the picture. We needed some help on this one. AquaCoustic Remote Technologies Inc., Vancouver, BC, Phone: (604) Fax: (604) Toll free :(888) Web page: 21

18 The City of Abbotsford Contract # Digital CCTV and Sonar Inspection This is the pipe traversing the wet lands at the start of the survey. This is the pipe traversing the wet lands at the start of the survey. The downstream end of 124E9, 125E9 siphon. AquaCoustic Remote Technologies Inc., Vancouver, BC, Phone: (604) Fax: (604) Toll free :(888) Web page: 22

19 The City of Abbotsford Contract # Digital CCTV and Sonar Inspection This is as close as we could come to manhole number 1005F8. Collecting centimeter accurate manhole positions at manhole # 1011F9. AquaCoustic Remote Technologies Inc., Vancouver, BC, Phone: (604) Fax: (604) Toll free :(888) subsea@uniserve.com Web page: 23