Packaged Metering Manholes from Openchannelflow are available with a wide range of options to help customize them to your particular application needs.  A key element of this customization is the variety of top styles available, with each top specially engineer for a site’s particular needs.

Grassy Areas

In grassy, non-traffic areas, Openchannelflow has a developed low-profile Domed Fiberglass Top.  The top is thoroughly reinforced and provided with a mounted with rugged stainless steel hardware – including an industry first standard fail-open gas strut. The fail open design greatly reduces the likelihood that an operator can become inadvertently trapped inside an Openchannelflow Packaged Metering Manhole and provides visual feedback if a site has been secured – reducing the likelihood of unauthorized access (a particular concern with Packaged Metering Manholes installed near subdivisons or urban areas). 

While not intended for it, Openchannelflow’s domed top has been live tested for vehicular loads.  In ground tests the top deflected under wheel loading by a CUV, but sprang back to shape once the load was removed.  This test, conducted three consecutive times, produced no visible damage to the top.  We stress, however, that the domed top is not intended for vehicular loads and the above test was conducted to verify the laminate design and top construction for extreme conditions.  When using domed top Packaged Metering Manholes near traffic areas, you may wish to use concrete bollards to ensure that traffic does not accidentally run over the top.

Pedestrian Areas

For pedestrian areas, Openchannelflow provides a wide opening Aluminum Top.  This top is unlike pedestrian solutions from other Packaged Metering Manhole providers.  It allows substantially more open area - 40% (Tracom) to 150% (Plasti-Fab) - to enter / exit the manhole.  The top rests on a full perimeter fiberglass flange at the top of the Packaged Metering Manhole.  The standard top is non-watertight, with custom watertight / gastight options (with somewhat reduced access space) also available.  

As with the domed top, the pedestrian access hatch is not intended to support vehicular traffic.  Like the domed top, pedestrian hatch Packaged Metering Manholes should be located away from vehicular traffic or protected by concrete bollards.

Traffic Areas

Vehicle traffic areas require a different approach to the top of the Packaged Metering Manhole. For these applications a specially constructed H-20 Traffic Reducer is available, onto which a traditional grade ring / frame / cover stack can be mounted.  Should the customer desire, Openchannelflow offers complete composite grade ring / frame / and cover stacks.  These stacks cost more than traditional concrete / cast iron stack, but provide an extra layer of protection against microbial induced corrosion (MIC).  Made from composite materials, these optional stacks also have the advantages of being lightweight and having no scrap value.

Here again Openchannelflow focuses on ease-of-use / ease-of-entry/exit.  H-20 reducers are available in 22-1/2”, 31-3/4”, 36”, and 38” openings.  

Specially Tops

While the above tops cover the majority of applications that you would expect to see a Packaged Metering Manhole used in, there are times when something a little more custom is needed.  For these times, Openchannelflow offers narrow opening grating and open top options.

In narrow opening grating tops, a flange is molded at the top of the Packaged Metering Manhole on the inside of the manhole barrel on to which narrow opening fiberglass grating is mounted.  The grating is typically split into two halves – allowing access to interior of the manhole.  Note that grating tops are not intended for deep Packaged Metering Manholes as an unsecured grate could constitute a fall hazard.  Grating top manholes work well in situations where a dedicated equipment shelter is place over the top of the manhole to limit access.  Like the open top option below, grating top Packaged Metering Manholes should only be used in applications where inflow is not a concern (or can be controlled).

When site customization is required, Openchannelflow offers an open top solution.  Here a flange is molded around the outside of the top of the manhole.  The flange provides a location onto which a top can be mounted, if necessary, or it can serve to anchor the opening of the Packaged Metering Manhole in a poured concrete slab.  There is no grating at the top and the unit is completely open.  Open top manholes work well in area where inflow is not a concern and access can be strictly limited.  Usually this means that a dedicated equipment shelter is constructed around it.