R2014-86 AUTHORIZING EXECUTION OF WATER DISTRIBUTION SYSTEM LEAK DETECTION SURVEY

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Project Approach For this project,ADS will use our standard methodology to conduct a leak detection survey. Some of the highlights of this approach include: • 3-Year Location Survey—ADS will conduct a leak detection/location survey with sonic detection equipment on approximately 487 miles of water main(approx.2,571,360 LF)over the course of 3-years. The system will be monitored by listening on all hydrants(within the selected areas)and selected main line valves and b-box or service valves with highly sensitive sound intensifying instruments. If necessary any and all PVC mains will be correlated from point to point with correlation distances not exceeding 500ft between contact points. • City Zones—These zones will be determined by the city and will be used to determine the geographical areas that will be surveyed in a specific time period. Each zone will be approximately 162.3 miles of water mains for each year of the survey. These zones have already been identified with our previous work with the City. • Mains Investigation—In areas showing indications of leakage,ADS will thoroughly investigate the mains and services with an electronic leak correlator to pinpoint the leaks for repair. • Systems Documentation—ADS will record all defective system components such as valves,hydrants and curb stops,as well as any map errors,that are noted in the course of carrying out other field activities. • Project Deliverables—ADS will prepare a final report showing the results of all tests and investigations. The report will include the location and estimated quantity of leakage found and cost benefit analysis of the survey,as well as the inventory of defective system components and map errors. Scope of Services ADS will conduct a leak detection/location survey with sonic detection equipment on the City's water system.We will survey the total length of water main estimated to be 487 miles over a 3-year period, or approximately 162.3 miles per year, and monitor the system by listening directly on all hydrants and selected main line valves, b-box, and service valves with highly sensitive sound intensifying instruments. For a project of this size, we propose two to three days sounding of the system followed by one to two days of resounding and correlating at each potential leak location.This approach will provide a set of organized results for the report that can be submitted to the city each week.ADS will perform two full days of sounding the system and marking down the potential leak sounds. One day will then be taken to return to those locations to see if the sound is still present.The sound may simply be due to usage and resounding will determine whether it is a leak sound. If it is a leak sound,the location will be further investigated with the electronic correlator. ADS will thoroughly investigate the mains, hydrants, valves and/or services with an electronic leak correlator and ground microphone to pinpoint the leaks for repair. Leak locations will be marked with Precautionary Blue Paint unless otherwise noted by the City. We recommend that all identified leaks be repaired while ADS engineers are still working in the city so that the immediate area can be sounded again in case another leak may have been masked by the original leak noise.ADS will correlate all PVC water mains from point to point with distances not exceeding 500ft—on particularly difficult to find leaks Hydrophone sensors may be deployed to assist the pinpoint of the leak. ENVIROASHNTAL • O /ICES 1880 W. Fullerton Ave. Chicago, IL 60614 Page 4 Client Initials