Slotted DRENOPAL ND/OD 1200 pipes and tee manholes

The objective was to disperse stormwater from a new urban infrastructure into the ground.
In this case, use of the two on-site watercourses as drainage run-off for the stormwater generated in the new area was not possible.
The choice, among the possible solutions, was the drainage trench for a number of reasons related to less intensive land use, ease of implementation and lower cost.
Three different drainage trenches were established for the design, using DRENOPAL ND/OD 1200 SN 8, high-density polyethylene, corrugated slotted pipes. Each 6 m pipe contains 6 slots, each of 1 cm in width and 12 cms long between one corrugation and the next along the entire circumference of the pipe.
This diameter was chosen because of the large storage capacity (the three trenches, 20, 76 and 40 m in length, have a total storage capacity of 112 m3), including an option for inspection when draining or washing.
Installation involved an excavation width of 3.20 m, the positioning of a geocomposite (to ensure containment of the gravel forming the drainage trench) and gravel filling with a grain size of 15/35 mm to facilitate, given the grain size, the rapid spread of water inside the structure and, simultaneously, to prevent the gravel from passing through the slots in the pipeline.