Thermoplastics piping and ducting systems - Rainwater infiltration and storage attenuation systems - Practices for underground installation

This Technical Report is applicable to the installation of rainwater infiltration and storage/attenuation systems under gravity.
This Technical Report covers installations including:
-   reservoirs made by assembled cuboid shaped thermoplastic boxes;
-   integral components;
-   ancillary components (e.g. access provisions and connections);
-   geotextiles and/or geomembranes;
-   embedment and backfill.
These systems are intended for underground use in landscape, pedestrian or vehicular traffic areas and are used outside building structures.
This Technical Report is only applicable to systems containing boxes to create a reservoir where the manufacturer has clearly stated in the installation instructions how the components should be assembled.
This Technical Report is a guidance document. It provides a set of general guidelines which gives best practice for installation.
NOTE 1   It is anticipated that additional recommendations and/or requirements (e.g. design, dimensioning and structural aspects) will be detailed in the relevant standards.
NOTE 2   Attention is drawn to the need to comply with national or local regulations.

Einbauanleitungen für Rohrleitungs-, Regenwasserversickerungs- und Regenrückhaltungshaltesysteme außerhalb von Gebäuden - Verfahren für den Erdeinbau

Systèmes de canalisations et de gaines en matières thermoplastiques - Pratiques pour la pose en enterrée

Cevni in kanalski sistemi iz plastomernih materialov - Sistemi za infiltracijo in zadrževanje shranjene deževnice - Postopki za vgradnjo pod zemljo

To tehnično poročilo se uporablja za namestitev sistemov za infiltracijo in zadrževanje shranjene deževnice, ki obratujejo s pomočjo gravitacije.
To tehnično poročilo zajema inštalacije, vključno s/z:
– rezervoarji, izdelanimi iz sestavljenih termoplastičnih zabojev v obliki kvadra;
– vgrajenimi komponentami;
– pomožnimi komponentami (npr. omogočanje dostopa in povezave);
– geotekstilijami in/ali geomembranami;
– območjem za polaganje in zasipom.
Ti sistemi so namenjeni za podzemno uporabo na krajinskih območjih, območjih za pešce ali prometnih območjih z vozili in se uporabljajo zunaj zgradb.
To tehnično poročilo se uporablja le za sisteme, ki vsebujejo zaboje za izdelavo rezervoarja, pri čemer je proizvajalec v navodilih za namestitev jasno navedel, kako morajo biti komponente sestavljene.
To tehnično poročilo se uporablja kot vodilo. Podaja nabor splošnih smernic, ki opisujejo najboljšo prakso za namestitev.
OPOMBA 1: Pričakuje se, da bodo dodatna priporočila in/ali zahteve (npr. glede oblike, dimenzij in strukturnih vidikov) podrobneje opisane v relevantnih standardih.
OPOMBA 2: Izpostavljena je zahteva po zagotavljanju skladnosti z državnimi ali lokalnimi predpisi.

General Information

Status
Published
Publication Date
30-Jan-2018
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
31-Jan-2018
Completion Date
31-Jan-2018

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SLOVENSKI STANDARD
SIST-TP CEN/TR 17179:2018
01-april-2018

Cevni in kanalski sistemi iz plastomernih materialov - Sistemi za infiltracijo in

zadrževanje shranjene deževnice - Postopki za vgradnjo pod zemljo
Thermoplastics piping and ducting systems - Rainwater infiltration and storage
attenuation systems - Practices for underground installation
Einbauanleitungen für Rohrleitungs-, Regenwasserversickerungs- und
Regenrückhaltungshaltesysteme außerhalb von Gebäuden - Verfahren für den
Erdeinbau

Systèmes de canalisations et de gaines en matières thermoplastiques - Pratiques pour la

pose en enterrée
Ta slovenski standard je istoveten z: CEN/TR 17179:2018
ICS:
13.060.30 Odpadna voda Sewage water
23.040.05 Cevovodi za zunanje Pipeline and its parts for
sisteme za odpadno vodo in external sewage systems
njihovi deli
SIST-TP CEN/TR 17179:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 17179:2018
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SIST-TP CEN/TR 17179:2018
CEN/TR 17179
TECHNICAL REPORT
RAPPORT TECHNIQUE
January 2018
TECHNISCHER BERICHT
ICS 13.060.30; 23.040.05; 23.040.20
English Version
Thermoplastics piping and ducting systems - Rainwater
infiltration and storage attenuation systems - Practices for
underground installation

Systèmes de canalisations et de gaines en matières Einbauanleitungen für Rohrleitungs-,

thermoplastiques - Pratiques pour la pose en enterrée Regenwasserversickerungs- und

Regenrückhaltungshaltesysteme außerhalb von
Gebäuden - Verfahren für den Erdeinbau

This Technical Report was approved by CEN on 17 December 2017. It has been drawn up by the Technical Committee CEN/TC

155.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 17179:2018 E

worldwide for CEN national Members.
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Contents Page

European foreword ...................................................................................................................................................... 3

Introduction .................................................................................................................................................................... 3

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and definitions ................................................................................................................................... 5

4 Symbols and abbreviations ......................................................................................................................... 7

5 Transport, handling and storage at depots and sites ........................................................................ 7

5.1 General................................................................................................................................................................ 7

5.2 Transportation of boxes and box components .................................................................................... 8

5.3 Handling ............................................................................................................................................................. 8

5.4 Storage ................................................................................................................................................................ 8

6 Installation ........................................................................................................................................................ 9

6.1 Behaviour of reservoirs ................................................................................................................................ 9

6.2 Design considerations ................................................................................................................................... 9

6.2.1 General................................................................................................................................................................ 9

6.2.2 Types of installation ...................................................................................................................................... 9

6.3 Excavation construction ............................................................................................................................... 9

6.3.1 Safety ................................................................................................................................................................... 9

6.3.2 Excavation width ........................................................................................................................................... 10

6.3.3 Excavation depth ........................................................................................................................................... 10

6.3.4 Excavation bottom ........................................................................................................................................ 10

6.4 Reservoir installation, procedures and control ................................................................................ 11

6.4.1 Handling ........................................................................................................................................................... 11

6.4.2 Installation using geotextile (infiltration or attenuation) ............................................................. 11

6.4.3 Installation using geomembranes (storage or attenuation) ......................................................... 13

6.5 Backfilling ........................................................................................................................................................ 13

6.5.1 General.............................................................................................................................................................. 13

6.5.2 Basic procedure ............................................................................................................................................. 13

6.5.3 Side and initial backfill ............................................................................................................................... 14

6.5.4 Recommended compaction methods .................................................................................................... 14

6.5.5 Main backfill ................................................................................................................................................... 16

6.5.6 Compaction quality control ....................................................................................................................... 16

6.6 Special precautions ...................................................................................................................................... 16

7 Ancillary components ................................................................................................................................. 17

8 Inspection and testing ................................................................................................................................. 17

8.1 Inspection ........................................................................................................................................................ 17

8.1.1 Inspection before installation .................................................................................................................. 17

8.1.2 Inspection after installation ..................................................................................................................... 17

8.2 Testing - Leak tightness testing for storage or watertight attenuation system ..................... 17

Annex A (informative) Classification of soils ..................................................................................................... 18

Bibliography ................................................................................................................................................................. 20

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European foreword

This document (CEN/TR 17179:2018) has been prepared by Technical Committee CEN/TC 155

“Plastics piping systems and ducting systems”, the secretariat of which is held by NEN.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

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Introduction

Ecological and sustainable rainwater management is an increasingly important subject for

communities, designers and other agencies. Due to the increasing 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 receiving surface water. This can cause flash flooding, water in

basements and other life threatening situations.

Rainwater harvesting, infiltration and decentralized retention of rainwater (attenuation), are examples

of ecological and sustainable rainwater management. Excess water from rainwater harvesting systems

should be infiltrated into the ground or released in a controlled manner into surface water bodies.

Plastic geocellular systems, sometimes referred to as ‘boxes’, are a preferred solution for temporarily

storing rainwater underground. These boxes can be stacked in layers to form underground storage

reservoirs (e.g. 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. Some boxes are strong enough to be installed under roads, parking

areas and other landscape features. They can also be recycled very easily.

This Technical Report contains guidance for installation procedures for thermoplastic infiltration and

attenuation systems outside building structures, which should be completed in conjunction with

product specific installation instructions.

This Technical Report is a guidance document only. It provides a set of general guidelines which gives

best practice for underground installation of thermoplastic infiltration and attenuation systems outside

building structures.

This Technical Report includes recommendations for the reservoir surround and backfilling procedures

but not road base and road sub-base details. Attention is drawn to any national regulations which may

cover these or other aspects of installation.

This Technical Report is intended to be used by local authorities, design engineers, installation

contractors and manufacturers.

In this Technical Report, much of the guidance is expressed as requirements, e.g. by use of “shall” or by

instructions in the imperative. It is strongly recommended that these be followed whenever applicable.

Other guidance is presented for consideration as a matter of judgement in each case, e.g. by use of

“should”.
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1 Scope

This Technical Report is applicable to the installation of rainwater infiltration and storage/attenuation

systems under gravity.
This Technical Report covers installations including:
— reservoirs made by assembled cuboid shaped thermoplastic boxes;
— integral components;
— ancillary components (e.g. access provisions and connections);
— geotextiles and/or geomembranes;
— embedment and backfill.

These systems are intended for underground use in landscape, pedestrian or vehicular traffic areas and

are used outside building structures.

This Technical Report is only applicable to systems containing boxes to create a reservoir where the

manufacturer has clearly stated in the installation instructions how the components should be

assembled.

This Technical Report is a guidance document. It provides a set of general guidelines which gives best

practice for installation.

NOTE 1 It is anticipated that additional recommendations and/or requirements (e.g. design, dimensioning and

structural aspects) will be detailed in the relevant standards.

NOTE 2 Attention is drawn to the need to comply with national or local regulations.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1610:2015, Construction and testing of drains and sewers

EN 13249, Geotextiles and geotextile-related products - Characteristics required for use in the

construction of roads and other trafficked areas (excluding railways and asphalt inclusion)

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
system
assembly including:

— a reservoir made by assembled cuboid shaped thermoplastic boxes (injection moulded or

extruded);
— integral components;
— ancillary components (e.g. access provisions and connections);
— geotextiles and/or geomembranes;
— embedment and backfill
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Note 1 to entry: See Figure 1 for an illustration of the meaning and limits of the terms used in this Technical

Report.
Key
1 cover layer
2 initial backfill bS horizontal clearance between the reservoir and the
excavation sidewall
3 ground surface b width of a trench cross-section
4 native (e.g. in situ) soil h height of the embedment
5 foundation zone hr height of the reservoir
6 main backfill α angle of the trench
7 side backfill w width of the reservoir
8 geotextile / geomembrane we width of excavation on surface level
9 bottom excavation
10 lower bedding
11 ancillary components
12 box including integral components
Figure 1 — Terminology infiltration/attenuation system
3.2
reservoir
assembly of boxes including integral components
3.3
ancillary components

products including inlets, outlets, ventilation, access for measurements and inspection

3.4
integral components
load bearing components contributing to the overall strength of the box
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3.5
main backfill
layer on top of the initial and side backfill

Note to entry: The requirements for the main backfill are dependent on the intended use of the surface.

3.6
initial backfill
layer of fill material immediately above the crown of the reservoir
3.7
cover layer
initial plus main backfill
3.8
height of the embedment

height of the lower bedding, plus height of the reservoir plus the height of the initial backfill

3.9
lower bedding

part of the construction which supports the reservoir on top of the excavation bottom

4 Symbols and abbreviations
For the purposes of this document, the following symbols apply.
b width of a trench cross-section (see Figure 1);
b horizontal clearance between the reservoir and the trench (see Figure 1);
h height of the embedment;
h height of the reservoir;
α angle of the trench;
w width of the reservoir;
w width of excavation on surface level;
M compaction class moderate;
N compaction class not;
W compaction class well.
5 Transport, handling and storage at depots and sites
5.1 General

Thermoplastics boxes and box components may be supplied with or without packaging.

Attention is drawn to the need for consideration of personnel safety during the transport, handling and

storage, especially in wet and cold weather conditions.
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5.2 Transportation of boxes and box components

Box and components should be inspected on delivery to ensure that they are marked appropriately and

comply with the specified requirements.

Any handling or transportation instructions from the manufacturer should be complied with.

Products should be examined both on delivery and immediately prior to installation to ensure that all

components have been delivered and that all components are free from damage and in accordance with

the relevant product standard.

Care should be taken to avoid positioning of boxes and components near to any exhaust systems or any

other potential contaminations such as diesel oil.

When boxes and components require specific transportation practices, the manufacturer should notify

the customer of the procedures to be used.

NOTE Attention is drawn to the need to confirm to national and/or local transport regulations.

5.3 Handling
When handling box and components, care should be taken to prevent damage.

When box and components are to be handled individually, they should be lifted, lowered and carried in

a controlled fashion and should never be thrown, dropped or dragged.

When loading or unloading box and components with forklift equipment, only forklift trucks with

smooth or suitably protected forks should be used. Care should be taken to ensure that forks do not

impact box and components when lifting.

The impact resistance of thermoplastics boxes is reduced at low temperatures; under these conditions,

more care should be taken during handling. Where cold conditions are expected, the advice of the

manufacturer should be sought.

NOTE In general cold conditions are considered if temperatures are lower than 5 °C.

5.4 Storage

Any storage instructions from the manufacturer and the requirements of the appropriate product

standards shall be adhered to.

All products should be stored in such a manner to keep them clean and avoid contamination or

degradation.

Excessive stacking heights should be avoided so that boxes and components in the lower part of the

stacks are not overloaded and/or the stack becomes unstable. Stacks of boxes should not be placed

close to open excavations. Strapping bands should not cause damage or deformation of the boxes or

components.

Stack the boxes on reasonably flat surfaces free from sharp objects, stones or projections in order to

avoid localized deformation or damage to the products.

Boxes and components should be stored on supports in very cold weather to avoid freezing to the

ground.

Storage in direct sunlight for long periods and/or high temperatures can affect the performance of the

products and should be avoided.

The fading of the colour caused by outside storage does not affect the mechanical properties of

products.

If boxes, box components and ancillary components are supplied in packaging, the restraints and/or

packaging should be removed as late as possible prior to installation.
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6 Installation
6.1 Behaviour of reservoirs

There are several methods of structural design (see national standards and guidance) that are used to

calculate the long-term performance of reservoirs.

The use of the installation procedures detailed in this Technical Report and the manufactures

instructions together with the structural design methods will ensure an optimal performance of the

reservoirs.

In general, vehicular traffic is not allowed on unpaved surfaces in the zone of influence of the reservoir

unless calculations prove otherwise.
6.2 Design considerations
6.2.1 General

It is essential to determine the soil conditions that relate to excavation construction and reservoir

installation prior to construction; the native soil and the backfill material should be classified in

accordance with Annex A. The classification is then used to choose a suitable type of installation in

accordance with 6.2.2.

The classification will also indicate where excavated material will be suitable for reservoir backfill, so

that importation of material may be minimized. Native materials conforming to classes 1 to 4 in

Table A.1 are all suitable as backfill in the embedment. If backfill materials have to be imported, it is

recommended that class 1 or 2 materials are used.
6.2.2 Types of installation
The three most common applications of thermoplastics reservoirs are:

— attenuation systems (could be wrapped in geomembranes or/and geotextiles). The sidefill material

and compaction requirements depend on the expected load and the performance of the reservoir;

— infiltration systems (mostly wrapped in geotextiles). The sidefill material and compaction

requirements depend on the expected load and the performance, and the infiltration capacity

required;

— storage systems (wrapped in geomembranes). The sidefill material and compaction requirements

depend on the expected load and the performance of the reservoir.
NOTE Reservoirs can have mixed applications.
6.3 Excavation construction
6.3.1 Safety
Operations in excavations are carried out in potentially hazardous conditions.

Shore, sheet, brace, and slope or otherwise support the excavation walls as appropriate to protect any

person in the excavation. Take precautions to prevent objects from falling into the excavation, or its

collapse caused by the position or movements of adjacent machinery or equipment, whilst the

excavation is occupied.

Excavated material should be deposited in a location and manner that does not endanger the stability of

the excavation.
National and local safety regulations must be complied with.
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6.3.2 Excavation width

The width of the excavation at the bottom of the reservoir need not be greater than necessary to

provide adequate room for the reservoir, ancillaries (e.g. separators, manholes) and their inlet and/or

outlet pipes when present and to provide enough space for sidefill compaction equipment. If not

specified otherwise the minimum value for b (see Figure 1) is 500 mm.

Wider excavations may be necessary for installations involving, for example, relatively deep burial,

unstable native soils or due to national regulations. Narrower excavations may be used when the

system design permits.
6.3.3 Excavation depth
The excavation depth is determined from:
— the reservoir design;
— size of reservoir;
— lower bedding properties;
— ground water level;
— local conditions such as load properties.

In general the cover layer should be at least 800 mm, if installed under vehicular traffic areas.

Shallower cover layer may be used when the installation is designed accordingly.

When determining the excavation depth, allowance for suitable bedding should be incorporated.

Sufficient cover should be provided in case of storage and attenuation systems with geomembranes to

prevent accidental reservoir flotation in potentially high ground water areas.

It is recommended to dig the complete excavation in advance of reservoir installation and to backfill

when the complete reservoir is installed.

Installation in frost conditions is not allowed unless special precautions are taken to ensure that the

installation area itself is free from frost.

Measures should be taken to keep the ground-water level at least 500 mm below the excavation bottom

during the complete installation.
6.3.4 Excavation bottom
6.3.4.1 Lower bedding
The lower-bedding at the excavation (see Key 10 Figure 1) should:
— have no slope unless provided in the design;
— be continuous, flat and uniform;

— be free of particles negatively affecting the functioning of the construction for example tree roots,

oversized or sharp particles and organic materials;
— have the storage capacity according to the design;

— for infiltration reservoirs, have the infiltration capacity according to the design.

Where over-excavation is needed due to rock, cobbles or hardpan, it is recommended that the material

for the foundation zone should be the same as for the lower-bedding zone.
Compact the foundation material uniformly in accordance with 6.5.2 and 6.5.3.
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6.3.4.2 Bedding

A reservoir requires uniform support for the whole of its bottom surface and this is provided by the

bedding layer. To provide this uniform support, the bedding layer should have a thickness of not less

than 50 mm. In general a thickness of 100 mm to 150 mm is recommended. The bedding should be flat,

smooth, straight, and free from sharp protrusions.

The material used should be granular, such as gravel, sand or crushed rock, and conform to 6.5.3.

The bedding material should be spread evenly across the full width of the excavation and levelled and, if

necessary, compacted.

For infiltration application the bedding material should have a water permeability not less than the

native soil.
6.3.4.3 Inlet/outlet preparation

Special precaution should be made to provide continuous support of the inlet/outlet pipe throughout its

entire length. Special care should be taken into account for the compaction under the inlet/outlet pipe.

6.4 Reservoir installation, procedures and control
6.4.1 Handling

Store and handle the boxes, box components, ancillary components, geotextiles and/or geomembranes

so as to prevent damage. Carefully inspect each product especially at jointing surfaces, for damage prior

to installation.
6.4.2 Installation using geotextile (infiltration or attenuation)

Check that the base of the excavation is kept smooth and flat. The base should be horizontal unless

otherwise provided in the design. Use two lines to create a right angle to act as a guide when starting to

install the boxes (see Figure 2).

In the case of infiltration, a geotextile (class 3 according EN 13249) with a filtration opening size related

to the surrounding soil infiltration rate is preferred. The geotextile should never be the limiting factor

with respect to infiltration rate.

The geotextile should be laid out on the bedding layer and up the sides of the excavation. Following

installation of the boxes the geotextile (provided by the manufacturer) should be wrapped around the

vertical faces and top surfaces of the reservoir. For geotextile it is not necessary to seal the joints, but

the geotextile sheets should have a minimum overlap of 500 mm.
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Key
A installation
B plastic boxes
C rope guidance
D excavation
Figure 2 — Order laying of the boxes (topside view)

In a typical installation using simple boxes, as an example start laying the boxes in the right angle

formed by the two lines (see Figure 2). First lay the longest row then gradually progress by constructing

the lateral rows. Start with the bottom layer and then progress layer on layer. Use clips in horizontal

and vertical direction to join the boxes together when prescribed. This method will ensure minimum

side fill widths are maintained. Variation of this method may be recommended for more complex

systems.

If needed, install ancillaries (e.g. plates, inlets, outlets) to complete the installation in accordance with

the manufacturer’s guidelines.

Before wrapping the system with the geotextile carry out the required preparation for [later]

installation of ventilation and access connections on the faces of the reservoir.

In case two or more reservoirs are installed at close distance in an excavation the minimum distance

between reservoirs should allow proper compaction and infiltration performance.
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6.4.3 Installation using geomembranes (storage or attenuation)

The minimum thickness and required mechanical properties of the geomembrane in relation to the

soil/ground water stresses should be specified by the designer taking into account the

recommendations of the box supplier.

Although special care for the design has to be taken (see 6.2), storage, logistics and excavation is the

same as for storage, attenuation and infiltration reservoirs (see Clause 5 and 6.3). The main difference

is the use of geomembranes (watertight sheets).

NOTE Sometimes geotextiles are additionally used for protecting the geomembranes from influenc

...

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