Depending on what the constituents make up an industry's flow stream, a sewer system's owner (city / county) may require pre-treatment and metering before the industry is allowed to discharge to the sewer.  For many industries, plant downtime is a major concern when installing a discharge monitoring system.

For many industries, plant downtime is a major concern when installing a discharge monitoring system.  Pre-cast or assemble on site solutions generally either take longer than the allotted downtime or push the installation schedule so that any delay will cause a cascade effect, hindering a time plant start-up. 

For this, and other reasons (e.g. measurement accuracy, corrosion resistance, single-source responsibility), many industries choose to install fiberglass Packaged Metering Manholes to measure their pre-treatment discharges.

Factory Integration

With a Packaged Metering Manhole system, the flume or weir is factory integrated into a fiberglass manhole.  The result is a single-piece / monolithic unit that is ready immediate installation.  The time required to install a Packaged Metering Manhole is considerably less than a new traditional pre-cast installation.

Slab Shortcuts

To speed the installation time, the industry can dig down to expose the line.  The required concrete slab can then either be poured in the excavation or the Packaged Metering Manhole can be mounted to a pre-cast slab prior to installation once it arrives - for a true drop-in-place solution. 

With the Packaged Metering Manhole pre-mounted, or the slab pre-poured in the excavation, flow through the line can be cut and the manhole lowered into place.  Once in place, the connections between the Packaged Metering Manhole and the line are made and then flow can resume - even before the Packaged Metering Manhole has undergone final leveling / securing it to the concrete slab.

Finishing the Installation

In many installations - both pre-cast and Packaged Metering - a shoulder has to be poured between the flume and the manhole barrel.  In the event of a blockage in the downstream pipe, the shoulder (or bench)  allows any standing water to drain back into the flume and out of the manhole once the blockage is cleared. 

To eliminate even this installation step, Openchannelflow has developed fiberglass benching for its complete line of fiberglass manholes.  The fiberglass benching eliminates the need to pour a shoulder (something that is often overlooked, resulting in contractor call backs).  Operator safety is also enhanced by the molded-in, non-slip diamond plate surface and maintenance requirements are reduced.