Instructions
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Dig a trench 15 cm deeper than the installation depth of the manhole and approximately wider 60 cm wider than the manhole diameter. |
Form a 15 cm thick bed from loose material (coarse sand or fine gravel) and compact to not less than 90% of the
Proctor Standard.
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Prepare the inlets and outlets on the base of the manhole using the cup drill and fit the specific gasket. |
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Place the base on the bed, connect it to the line and check that it is level. Connection with Pipes: clean the gasket; lubricate it and push the pipe inside the hole in the manhole as far as the stop point |
Completely backfill the base with the same material and again compact to not less than 90% of the Proctor Standard, proceeding by layers of 30 cm.
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If the manhole is supplied in elements, proceed with the construction of the manhole inserting the appropriate Hofit gasket between the base and the elevation(s) and between the latter and the upper unit. |
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After checking the perfect positioning of the gasket, clean and lubricate the housing surface and groove; the elements can then be assembled merely by pressing the body weight on top of them. |
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If necessary, cut the top neck of the element by following the marked lines. |
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The digging may be backfilled after construction, taking care to use suitable material, and compact in 30 cm layers to not less than 90% of the Proctor Standard. |
Heavy Loads: If the manhole is installed on a roadway or in areas subjected to heavy loads (group 3 or higher according to EN 124 - 1999), a concrete slab is necessary.
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The slab must be fitted in the ground compacted to a density of not less than 95% of the Proctor Standard. |
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Thanks to the particular elastic properties of the HOFIT gasket, any later connections to the manhole (private users, drains, etc.) may be carried out even after installation. |
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WARNING: Until completion of Installation, Machinery must not come closer than 1.5 m to the Manhole. |
Download Installation Instructions
INSTALLATION IN THE PRESENCE OF GROUNDWATER
In the presence of groundwater, any buried structure receives floatation force equal to the volume of water occupied, thereby putting the stability of the structure at risk. It is therefore important that the design takes into account this phenomenon.
The anti-buoyancy rings designed by HOFIT are special but simple devices installed directly in the structure of the HDPE manhole to guarantee the stability of the installation even in difficult conditions.
Calculations show how under even the most critical conditions the manhole maintains its stability. HOFIT is able to check the specific situation for the Customer’s Project, taking into account:
- deadweight of the manhole and its cover.
- weight of the soil placed directly on the terminal element of the manhole.
- weight of the soil placed on the anti-buoyancy rings.
- weight of the truncated cone portion which rests on the deepest anti-buoyancy ring.
- connection pipes, which are cut or withdrawn to raise the manhole.
- friction between the walls of the manhole and the particular surrounding soil.