Liner installation
A 300g Geotextile protection layer should be laid onto the base area of the hole in preparation for the liner. Using the diagram which has been drawn onto the pre-fabricated box weld panel, position the membrane to be unfolded as instructed. Once unfolded, the sides of the tank membrane will be apparent. There will be enough membrane for the height of the tank plus 200 mm to go on top which will help with the sealing of the tank at the later stage.
Stormwater Modules
The installation of the Stormwater Modules should match up to the attenuation tank size on your drawing to be clipped and connected as per the manufacturer’s instructions. Whilst the modules are being installed, the low-level outlet/inlet top-hats can be sealed to the tank. This can be done by completely installing the base layer of modules and marking the invert level of the pipework. The modules nearest the inlet/outlet can be removed temporarily and the hole for the pipework cut out, the top-hat can be positioned on the outside of the tank. Once the position has been decided, the top-hat can be sealed using the tape provided. After all the lower level pipes have been sealed and the modules have all been installed, the lid panel can be placed on the tank.
Sealing the tank
The pre-fabricated lid panel will fit the exact area size of the attenuation tank. This should be unrolled and unfolded into position as per the diagram. A check to ensure the lid panel is clean, dry, free from dust and dirt before the taping can be applied. Double-sided tape can be used open side, down to the perimeter of the lid panel using a roller or similar, apply pressure to make sure the tape has adhered correctly. The sides of the tank membrane can be pulled up and weighed down into position. Once all sides are up, a final check must be made to ensure there isn’t any excess material on the sides of the tank and that the material is relatively taught. The backing can be removed from the double-sided tape in sections and again pressure applied to ensure correct adhesion. The corners of the tank can be sealed by folding the membrane down and making sure extra tape is used to get a water tight seal.
Pipe outlets/inlets
The upper pipework top-hats can now be applied to the tank by positioning the top-hats at the required invert level, cut out the membrane to accommodate the sleeve then tape the top-hat in the correct location. The vent pipe should be positioned and sealed in the same way.
A 300g geotextile protection layer should now cover the tank on all sides and the top of the tank, thus completing the installation of the box liner.
*Scott Parnell Water Management Ltd offer a full test and validation service for all self-install attenuation tanks*
