03-G-4 Accept W/S Rate Study - Laserfiche WebLink

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Proposal Comprehensive Water Distribution System Audit As an example, for a tracer concentration, C, of 50,000 the transfer standard be followed. Additionally, the transfer mg/L, and a tracer flow rate of 0.01 gpm, and a standardshouldbecalibratedbeforegoingtothefield, and downstream tracer concentration of 5.0 mg/L, the process alter being used in the field. flow rate is calculated as, For pitot tubes, the assumption that the average flow in the 0.05 x 50,000 = (0 + 0.05) x 5.0 pipe is being measured is important. Pipes exhibit a parabolic velocity profile, and multiple measurements are 500 = 5 Q + 0.05 required to obtain accurate results. C) = 100.01 gpm After evaluating each meter's installation, the Carter & Burgess Team will use the in situ calibration procedure that The selection of the tracer is critical. The tracer cannot read is most appropriate for each meter. with any of the other cam pounds in the process flow for the proceduretobeaccurate. Additionolly, itisdesirabletouse Leak Detection a tracer that is not present in the process flow, because the The location of leaks in the distribution system con be very need for a background sample upstream of the point of challenging. One ofthe most common waysto locate leaks tracer addition is eliminated, isto use geophones and listen for leaks in the system. This procedure is generally quite precise, and it will provide Mixing in the pipeline is important. The basic assumption is some relative indication ofthe size ofthe leak. However, thatthetracerwill beuniformlymixedwiththeprocessflow the procedure is best employed when the approximate sotbatthedownstreamtracerconcentration measuredison location of the leak is known. For a distribution system accurate indication ofthe actual downstream concentration, wide study the exclusive use of sonic detection methods is generally cost prohibitive. The rate of tracer addition must be known with good accuracy for this method to be used. The rate oftracer addition is usually determi ned by ti ming the draw down in the calibrated tracer container. For this reason a graduated cylinder is usually used as the container. The metering pump must pump at a constant rate, therefore, multiple volume readings ,~, are taken on the calibrated container. Transfer Standard The use of o transfer standard to calibrate flow meters is relatively common place; however, it is important to document that the transfer standard is properly calibrated. Transfer standards used for flow meter cahbration usually Fortunately, there are some stepsthat con betaken to narrow includeeitherclamp-onuJtrasonicmetersorpitottubes. If downtheareastobeinvestigated. Inmostcitiesthenight- used correctly, eider instrument can Junction adequately as time water consumption for residential/commercial uses is atransferstandard. AtypicaJtransferstandardinstallation quitesmall, especiallybeh~veen2amand4am. I)udngthis is shown in Figure 5. time, portions of the distribution system con be isolated and water elevations in the elevated tanks monitored. Falling It is important that the recommendations for proving an water elevations are an indication of possible leaks. undisturbed flow path both upstream and downstream of Carter Burgess