For attenuation systems Hewitech LLPE Membrane is wedge welded and the joint air tested at 1 bar in accordance with “CIRIA 698 Site handbook for the construction of SUDS“. C698 states – “All storage tanks should be fully sealed in accordance with waterproofing standards, i.e. welded joints rather than adhesive tape, and the integrity of the seal checked through non-destructive testing, to ensure it is leak-proof.”
Attenuation tanks and soakaways are installed in an excavation prepared and backfilled by the contractor.
For protection the LLPE Membrane is surrounded with a 300g needle punched non- woven geotextile
Hewitech have experience installing complex tanks with the Variobox sited and membranes welded around pipe caps and crane bases