Field Flow Testing of Four Large Primary Influent Meters, Twin Cities Metro Waste Treatment Plan

Abstract

The St. Anthony Falls Hydraulic Laboratory performed field flow measurement tests on two large meters for the Metropolitan Waste Control Commission (MWCC) at the Metro Waste Treatment Plant in August and September 1990. These two 72-inch magnetic flow Dieters, designated MOOIA and MOOID, were retested by SAFHL in May and June 1991. After the earlier round of testing, the removal of considerable amounts of scum and grit from upstream. of the meters necessitated retesting in order to determine if the build-up had affected the accuracy of the meters. The tests were completed as a subcontract to James M. Montgomery Consulting Engineers, Inc., of Wayzata, Minnesota, with whom the MWCC had contracted to conduct an overall evaluation of these and other meters. The meters were tested using the dye dilution technique for which dye was injected just downstream. of gate 454. Continuous monitoring of the effluent and withdrawal of discrete samples was done at the metering tunnel discharge location into the east primary influent channel (See Fig. 1). Throughout the testing process all dye dilution samples were analyzed separately using fluorometers operated by both SAFHL and the research and deVelopment staff at the MWCC. Further insight into the dye dilution metering theory, as well as field procedures and complete results of the initial testing, may be found in the St. Anthony Falls Hydraulic Laboratory Project Report No. 311