Res 1996-129 - Laserfiche WebLink

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6zl^ Phase II - Phase II will commence upon completion of the rehabilitation activities and with the CITY's approval. A. Post Rehabilitation Flow Metering Six (6) temporary gravity flow meters will be used by the ADS to establish wet and dry in-situ capacity and incremental inflow and infiltration volumes in Sub-basin 10. This information will be utilized to determine rehabilitation effectiveness. Field Identification of Metering Sites A field review of the metering sites will confirm the adequacy of the site from a hydraulic and engineering standpoint. Any debris or sediment that would influence the determination of wastewater flows will be removed or another appropriate site located. All proposed sites will be approved by the CITY prior to meter installation. Flow Monitoring Period The temporary flow monitoring installations will consist of flow met~rs and rain gauges that will be maintained for a period of 60 days depending on rainfall. The CITY will have the option to extend or reduce the monitoring period. Flow Monitoring Equipment The basic instruments to be used to monitor gravity flows are velocity/depth flow meters. These meters are totally self-contained units that automatically measure and record both depth and velocity of fluid flow in sewer systems at programmed intervals. The measurement of velocity is achieved using doppler velocity sensors. These sensors have no moving parts to foul and are designed to prevent collection of debris. The measurement of depth is achieved by multiple depth sensors which are sensed to the nearest 0.01 foot. The monitors are completely watertight to function properly under surcharge conditions. Calibration, Installation, Operation & Maintenance ADS will perform hydraulic calibrations at each site to understand the unique hydraulic characteristics. At least 4 independent verifications (by an independent device) of the depth of flow and the peak velocity measurement will be performed. These verifications are performed at various times of the day to capture the full range of flows for each site, i.e., early morning, mid-day, late night, etc. In addition, ADS will attempt to gather this data during differing weather conditions in order to ascertain calibration in the widest possible range of conditions. The distribution of flow velocities within the G:\DALLAS\CO NTRA CT\SAN MAR C. 0 OC June 25, 1996