Laying base

Drening can be placed over different types of surface. The dig-depth depends on ground stability, root zone, insertion systems levels and estimated water discharges that is the the existence or depth of the aquifer. Over the excavation a gravel bed have to be placed, its minimum thickness of 10 cm. The gravel have to be washed in order to avoid fine particles that may obstruct the insertion in the basin bottom.The gravel can be of river derivation, or crushed stones, grain size 20-40 mm, in order to avoid the obstruction of Drening® chambers side holes by smaller stones. The layer of grave on the base aims to the sabilization of Drening bed place to create a draining layer and help the insertion. In fact it have to be consolidated through rolling or mechanical compactor. Estimated accumulation gravel capability is of 30% of its volume. However, the designer and the applicant company are the ones in charge of the load capability and of the excavation base insertion capability. Then, before the system designing, a geotechnical survey of the Drening placing area is also needed. it is recommended a prediction of a 0.1% slope in the direction of the basin’s end. Soft grounds with a load capability lower than 96 kPa need the valuation of a geologist to adopt a specific solution. An increase of the gravel placing bed thickness is also recommended in order to increase the foundation’s load capability. Finally, the place of a non-woven fabric or of a thermoplastic net with a knitting lower than 20×20 cm between the placing bed and the Drening base is needed.

Drening chambers place

Drening chambers place have to be made completely by hand. For a correct place, the Drening chamber have to be linked in longitudinal direction to the ground chamber placing it at 30° in respect to the placing bed and hooking it from top to bottom. In the cross-direction, Drening chambers have to be simply pull near one another without hooks, leaving a 10 cm gap between the  mid rib base of the further elements.

 Drening chambers backfill

The first thing to do, after the place of the Drening element, is fill the gap between the excavation, the perimetral chamber and the interstice between the across combined chambers. During this stage is forbidden to climb into the chambers with any mechanical means. Moreover, the place of a geo-textile strip for the containment of the excavation’s sides along all the dig perimetral, is recommended. The geo-textile have to be placed under at least 3 Drening and then put on top of the separation geo-textile.

 Drening chambers covering

After the backfill, the next step is the covering of Drening chambers, with a minimum thickness of 15 cm of washed gravel to avoid the fine particles that may obstruct the seepage at the bottom of the basin. The gravel can be of river derivation or crushed stones, grain size 20-40 mm, in order to avoid the obstruction of Drening chambers side holes by the smaller stones. During this stage, only the climb into the chambers with medium tonnage track vehicles is allowed and the gravel thickness between the Drening top and the caterpillar base must be of 40 cm. The costumer is in charge of the observance of load limitations. Geoplast S.p.A is not liable for incoveniences caused by the use of overburden no-track vehicles with gravel thickness lower than 40 cm. An entry angle of the mean equal to 45° in respect to the basin axis is recommended in order to enter into the basin with mechanicals means during all the gravel filling operations and to avoid the move of Drening chambers. The entry angle is also important to avoid the climbing perpendicularly and laterally to the caps moving the no-consolidate gravel.

THE STRENGTHS

DRENING is the only system that allows the easy and cheap realization of an underground basin and the regulation of rivers flow thanks to the subsoil seepage of rainwater.

 Moreover, thanks to its high mechanical resistance, the space above can be used for roads, parking lots and green areas. Then, it permits the reduction of flowing water towards the valley and the drainage of green areas such as: soccer fields or greens. Drainage of water from the road to the edge of the pavement.

Draining dugout for the closure of the small channels at the edge of the roads. Accumulation and dispersion chambers can be inspected and cleaned thanks to access holes which can be found over Drening.

ADVANTAGES COMPARED TO TRADITIONAL METHODS

Increase of the volume and of the percolation surface with the simultaneous increasing of the disposal speed. Decrease of the excavation depth with related raising of the safety distances from the groundwater and reduction of the quantity of filling gravel.

Reduction of the dugout lenght in respect to the system pipe and gravel. Fast and simple placing without the help of a crane or of an new elevetor.

 DRENING is made of plastic material regenerated from PP (Recycled Polypropylene) and it is untouchable by the chemical agents that can be found in wastewater. Increase of the quantity of circultating air that is essential to guarantee the survival of the aerobics bacterias that are in charge of the dissociation of organic substances in wastewater.