Tools for good drywell operation – fibre cloths, etc.


Tools for good drywell operation – fibre cloths, etc.

It is very important to prevent leaves, sand, etc., which can accumulate on roof surfaces and in roof gutters, from entering the drywells, since these materials can contribute to the inflow pipes blocking or simply to the drywells' hollow space filling up.

Various tools are used for this.

Roof well

Concrete and plastic roof wells are available in various dimensions and the purpose of these is to keep away sand and leaves etc. from the roof water before it runs into the drywell.

Please refer to the relevant websites, such as Uponor.

Fibre cloth

For setting up drywells of plastic materials, etc., different types of fibre cloths are used to prevent sand from getting inside the drywell. The thinnest types of fibre cloth, which also have the highest water flow, are generally used – e.g. DuPont Typar SF27. The fibre cloth can still get clogged at times so that it is difficult for the water to escape into the ground, which, after all, was the original purpose of the drywell.

When the fibre cloth gets clogged, it always happens in places where fine-grained material combined with clay or oil particles appear and settle in the fibre cloth. Even though suitable sedimentation basins have been installed, the fibre cloth can still get clogged.

The solution to this problem is to use pea-sized stones instead of a fibre cloth. BIO-BLOK® 80 HD G consists of a vertical net tube with a diameter of approx. 7 cm. The external net tubes which are in contact with the ground must therefore simply be filled with small stones which will act as a coarse filter instead of the fibre cloth. The backfilling of the excavation from installing the drywell must naturally be carried out with such coarse materials that infiltration of the fill material through the gravel to the drywell is avoided. See the drawing below:

With the above solution you can avoid the problems which can, for example, arise with corresponding competing products (see below) which, even though they can be TV inspected and hosed, are impossible to rinse using a hose because the water from the hose would be unable to gain direct contact with the fibre cloth. Any decomposed sludge cannot be collected, either, since the sludge would be located between the tube structures and the base of the drywell.

The conclusion is that if you use EXPO-NET's suggestion you will get the most secure operational solution with the best options for avoiding clogged drywells.