SADE Special Works’ finest manholes for the SIAAP north-east outfall
To transport wastewater to its pre-treatment and treatment facilities, the Greater Paris Sanitation Authority (SIAAP) manages a 440km network composed primarily of outfalls with manhole access. The rehabilitation of 11 manholes, along the north-east outfall, was entrusted to SADE Special Works.
A similar task across the board…
For 10 manholes of 20m to 65m in depth, all equipped with a concrete staircase, SADE Special Works’ task was to clean, purge coatings, apply a special mortar for hostile environments and, where necessary, replace or install safety features such as handrails.
…with one exception…
Located in the immediate vicinity of Porte de Montreuil, access to manhole n°39 is prohibited to operators and subject to specific works due to its configuration. Up to one third of its height fills with the water from a large collector which falls some 35m lower into the outfall operating with a 0.4m propeller and running around the manhole. The 2.4m-diameter shaft thus offered a workable diameter of just 1.6m for its rehabilitation.
…and a tailor-made solution
The solution chosen for its rehabilitation consisted of surface cleaning, the demolition of the concrete staircase, resurfacing of the walls and the fitting along its entire height of a GRP shaft (1,500mm-diameter) housing a 316L stainless-steel spiral staircase which is thus isolated from the falling waters.
A high-precision operation
Executed on an almost autumnal summer morning, the laying and assembly of 6 sections of the staircase in its shaft was a meticulous operation, in terms of both timing (between two spells of heavy rain) and precision, with 5cm to play with between the staircase and the wall.
These impressive rehabilitation works testify to SIAAP’s trust in the expertise of SADE’s ‘all terrain’ teams.