Attenuation Tanks & Storm Cells
In Accordance With The SuDS Manual
Visual Inspections & Seam Testing

Attenuation tanks can help to reduce, or even eliminate flooding, erosion, and damage caused by flooding during extreme rainfall situations. They are often used in SUDS or in areas where large amounts of non-porous material stops the natural water runoff into grass, soil and waterways. The Attenuation tank manages extreme rainfall events by temporarily storing excess run-off water and then returning it to the normal drainage system in a controlled manner. 

CIRIA 753 Chapter 30.5.4 (Geomembranes and Geocomposite Clay Liners used as Waterproof Barriers)

In this chapter it states that. 

“Leakages can occur due to poor field or factory seaming, or damage caused during or after installation. Geosynthetic barriers and especially geomembranes should be installed by experienced and suitably qualified staff.”

“Independent verification of the installation of waterproof membranes and lining systems on site is critical to achieving the performance required & to avoid failure. This is acknowledged by British Standards and CIRIA C753 which specifies that:”

“All joints and seams are visually inspected and tested on site to ensure that they meet the required standard. The main places where leaks are likely to occur is around penetrations, such as where a pipe passes through the material (eg where a pipe passes into a lined tank)”

Design Verification Plans

Design Verification plans should outline the required performance verification activities (inspection and testing), the relevant personnel to be used and the types of records to be collected. The greater reliance that is placed on the barrier, the greater the verification requirements. GeoShield offer, across the globe, comprehensive Waterproofing & Lining Inspection programs that cover all aspects of design, application, training, monitoring, recording & reporting that will unquestionably reduce the element of human error.

Independent Verification

CIRIA 753 states that “The verification should be carried out by a third party that is independent of the installer of the barrier.” The Environment Agency has also provided clear advice with respect to the level of independence and verification. The Environment Agency recommends, “Conflicts of interest in verification should be avoided in the field of contaminated land verification (EA, 2010). The same philosophy should apply to verification of geomembranes in SuDS.

Verification Test Methods For Geomembranes After Construction

Test methods used on geosynthetic barriers in SuDS can be sub divided in to two main elements