TEPPFA - Infiltration TEPPFA guidance for installation

Gene Kelly might be forgiven for Singing and Dancing in the Rain but there must be a betterway to prepare for the disruptive flooding caused byMother Nature. Now a new installation manual describes how to install plastic infiltration systems. It won’t stop the rain above ground but it will tell you how to control its disappearance below ground.

TEPPFA has published its ‘Guidance for the installation of rainwater infiltration and storage/attenuation systems.’ The publication is full of practical advice and tips for designers and installers alike.

These plastic boxes are becoming the preferred solution for temporarily storing rainwater underground. They can therefore be stacked in layers to form underground storage tanks.

The manual spells out the distinction between infiltration and attenuation techniques. The former stores collected rainwater temporarily in a tank surrounded by geotextiles. Geotextiles have the property to prevent the passage of sand, organic and mineral particles, whilst allowing water to flow into the tank. This water is gradually released into the surrounding soil.

With the attenuation method, the tank is surrounded by an impermeable membrane. Storm water is also collected but piped off via a flow control device.

Design and Installation

A design flow chart is provided to assist in the design stage for each application. Storage and load calculations are not supplied since these vary according to the type of unit. However, they are available from respective TEPPFA members.

For the contractor, installation is of particular interest and this section deals with storage of boxes and logistics, building a ramp, trench excavation, suitable subsoil conditions and the bedding layer. One valuable tip is given for when proper alignment is not possible because of an irregular base. This involves sectioning off the installation and filling the spaces (at least 40 cm across). Connections between the sections can then be secured by standard pipes.

Adequate attention is also afforded the various types of geo-textiles and geo-membranes that are preferred and how they should be applied. And once the installation is completed, inspection is reviewed and guidance provided.

Download ‘Guidance for the installation of rainwater infiltration and storage/attenuation systems’.

Infiltration Units – All You Need to know about the Flow

French version

German version

Polish version

To the uninformed, plastic infiltration units might look likelarge beer crates! But the semblance ends there but not the questions. Experts at TEPPFA have drawn up some FAQ’s of their own. Their answers and units clearly hold water…

Developed in the early nineteen nineties, these modular plastic boxes for underground rainwater infiltration, attenuation and storage systems have gained in popularity. Many civil engineers throughout Europe use these simple yet ingenious devices to mitigate flooding and land subsidence through harvesting rainwater and then releasing it gradually. Keen to promote their use further and uphold quality assurance, a group of experts has recently tabled nineteen FAQ’s.

Even though these units are easy to install, digging a hole to bury them is not quite enough. An essential question therefore deals with ‘which parameters are important for designing an installation?’ Design criteria such as strength, volume, capacity and the avoidance of pollution are therefore explained.

A step by step checklist is provided for installing the units alongside calculations for accommodating load bearing capacity. Also useful to know is that these installations can be inspected by most sewer cameras. Cleaning and maintaining are equally covered.

When it comes to stating maximum installation depth, there is no exact answer. However, all TEPPFA members have the design calculations at hand and these are worked out by factors such as long term strength of the box, the kind of application (infiltration or attenuation), level of groundwater, surrounding soil type, traffic load and the final design configuration.

Various other guidelines and practical diagrams are included that assist in the installation purpose. Peter Verlaan, a member of the panel that drafted the FAQ’s is confident that they will lead to a greater understanding of the various possibilities that these systems offer:

“We are currently drafting standards at TEPPFA for these innovative infiltration systems and hope to publish these shortly. Whereas the present European annual market is estimated at 1 million units, we predict a twofold increase over the next five years. Rainwater and hence flooding is becoming a persistent feature of weather patterns particularly in NorthernEurope. The more information we can publish about these systems, the better!”

“They are cost effective and highly efficient. Successful rainwater management is all about making the right informed choices. This is why we shall continue to communicate the essential details of their installation and thus promote their benefits.”

A full list of the FAQ’s can be downloaded here

Guidance for the installation of rainwater infiltration and storage/attenuation systems

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Rainwater management is an increasingly important subject for communities, designers and other agencies. Due to the excessive amount of impermeable surfaces being created by buildings and roads, rainwater falling in urban areas can have great difficulty in finding its way into the ground or to nearby rivers. This can cause flash flooding, water in basements and other life threatening situations.

Plastic boxes are the preferred solution for temporarily storing rainwater underground. These boxes can be stacked in layers to form underground storage tanks able to store run-off from intensive rainfall falling over large surface areas. Plastic boxes have the advantage of being light and easy to install whilst providing a large capacity for storage relative to their overall volume. They are strong enough to be installed under roads, parking areas and other landscape features. They can also be recycled very easily.

Furthermore they can often represent the most cost effective solution for customers.

This “Guidance for Installation” explains the application fields of infiltration and attenuation and the basics for installation. It provides designers with guidance on the configuration of applications. The design and installation of infiltration and attenuation applications is also discussed. The guide also provides valuable information relating to inspection, and filtering of the rainwater.