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Flow monitoring manholes for industrial discharge complianceWith the advent of the Packaged Metering Manhole (PMM) in the 1960’s, monitoring wastewater discharge compliance by industrial customers became considerably easier.  By factory integrating a primary device (usually a flume or weir, but mag meters can also be installed), into a fiberglass manhole structure, Packaged Metering Manholes reduce, or eliminate entirely, many of the problems associated with trying to retrofit a monitoring system into an existing structure. 

With thousands of installations throughout North America, Packaged Metering Manholes have been shown to provide:

  • Reductions in installation manpower and equipment
  • Shorter installation downtime
  • Improve flow measurement accuracy
  • Increased operator safety
  • Lower lifecycle costs (little to no maintenance and resistance to MICC)
  • Substantial reductions in infiltration

Above and beyond all other considerations is the fact that Packaged Metering Manholes provide monitoring agencies a centralized point from which to safely conduct a flow monitoring and sampling program.  With all flows directed into upstream collection manholes (or in some cases the Packaged Metering Manhole itself), the total flow out of a industry can be monitored and characterized. 

Further, factory integration of the primary device into the manhole structure means that flow accuracy is improved.  Flumes that otherwise would be difficult (or not economical) to install in a concrete manhole or vault can be easily integrated into a Packaged Metering Manhole.  Any portions of the flume or end adapters that can’t be accommodated in the manhole barrel itself are strengthened, covered, and then glassed to the manhole barrel – allowing the point of measurement to be conveniently located inside the manhole for inspector access.

While the unit cost of a Packaged Metering Manhole is greater than a pieced together concrete manhole / vault solution, the advantages of factory integration, increased accuracy, and reductions is line downtime and installation costs more than offset any upfront differences in price.

For monitored industries, there is also the added benefit of know that the metered flows are representative of what is discharging from the plant; they are not based upon the incoming water meter and are generally not susceptible to inflow into the manhole (as can be the case of precast manholes / vaults).  This true number discharge can result in substantial cost savings for industries that incorporate water into their final product or which are subject to large evaporative losses.

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