Module system for an underground stormwater retention basin, parts for such module system and stormwater retention basin and methods of building such stormwater retention basin

A unit for a module system for use as underground stormwater retention basin,

• the unit being a three-dimensional unit comprising at least one main surface and at least three side surfaces, each said side surface extends from a common boundary between the at least one main surface and the respective side surface, and where neighbouring side surfaces are angled in relation to each other,
• each of the side surfaces having side edges extending from corners of the at least one main surface, and each of the side edges of one side surface being mutually joined with a side edge of another, neighbouring side surface,
• where the three-dimensional unit has an inner volume and at least one through hole in one of the side edges, said three-dimensional unit either allowing water to be contained inside the three-dimensional unit or, with the proviso of the three-dimensional unit having at least two through holes, allowing water to pass through the three-dimensional unit from one through hole in one side surface to another through hole in another side surface, and
• where the at least one through hole is either a female through hole or a male through hole, and with the proviso that the through hole is a female through hole, the through hole is for insertion of an insert flange of a male through hole of another three-dimensional unit, and with the proviso that the through hole is a male through hole, the through hole has an insert flange for insertion into a female through hole of another three-dimensional unit
• which three-dimensional unit is made from at least two individual parts being mutually joined, thereby forming an inner volume of the three-dimensional unit, each individual part having at least parts of both the main surface and the side surfaces, and
• at least one of the at least two individual parts having at least one of the following:
• part of a female through hole, part of a male through hole, an entire female through hole, an entire male through hole, and
• where at least part of each of the side surfaces has a free edge directed oppositely to the common boundary between the at least one main surface and each of the side surfaces, each of said free edges having means for connecting, in a watertight manner, with free edges of side surfaces of another individual part of the three-dimensional unit enabling forming a watertight three-dimensional unit made from the at least two individual parts,
• the means for connecting, in a watertight manner, the free edges with free edges of closed side surfaces of another individual part of the three-dimensional unit consisting in at least one of a longitudinal bead and a longitudinal groove, said longitudinal bead or longitudinal groove intended for engaging a corresponding groove and bead, respectively, along free side edges of closed side surfaces of another individual part of the three-dimensional unit, and
• an elastomeric liner provided in the longitudinal groove of the individual part or engaging a longitudinal bead of the individual part, and if the elastomeric liner is engaging a longitudinal groove, the elastomeric liner intended for also engaging a corresponding bead along free side edges of closed side surfaces of another individual part of the three-dimensional unit, and if the elastomeric liner is engaging a longitudinal bead, the elastomeric liner intended for also engaging a corresponding groove along free side edges of closed side surfaces of another individual part of the three-dimensional unit.