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TECHNICAL APPROVALS FOR CONSTRUCTION

APPROVAL

INSPECTION

TESTING

CERTIFICATION

Fränkische Rohrwerke Gebr. Kirchner GmbH & Co KGHellinger Strasse 197486 KönigsbergBavariaGermanyTel: 00 49 95 88-490 Fax: 00 49 95 25 88-92 490e-mail: horst.doerr@fraenkische.dewebsite: www.fraenkische.com

British Board of Agrément tel: 01923 665300Bucknalls Lane fax: 01923 665301Garston, Watford e-mail: mail@bba.star.co.ukHerts WD25 9BA website: www.bbacerts.co.uk©2011

The BBA is a UKAS accredited certification body — Number 113. The schedule of the current scope of accreditation for product certification is available in pdf format via the UKAS link on the BBA website at www.bbacerts.co.uk

Readers are advised to check the validity and latest issue number of this Agrément Certificate by either referring to the BBA website or contacting the BBA direct.

FRÄNKISCHE STORMWATER MANAGEMENT SYSTEMS

RIGOFILL INSPECT STORMWATER MANAGEMENT SYSTEM

PRODUCT SCOPE AND SUMMARY OF CERTIFICATE

This relates to the Rigofill Inspect Stormwater Management System, for use as sub-surface water storage or as a soakaway to manage run-off from impermeable surfaces.

AGRÉMENT CERTIFICATION INCLUDES:• factors relating to compliance with Building

Regulations where applicable• factors relating to additional non-regulatory

information where applicable• independently verified technical specification• assessment criteria and technical investigations• design considerations• installation guidance• regular surveillance of production• formal three-yearly review.

KEY FACTORS ASSESSEDSystem design — information is provided in the Certificate to assist in the design of a stormwater management system (see section 5).

Strength — the system has adequate strength and stiffness to resist long- and short-term loads when used in accordance with this Certificate (see section 6).

Resistance to chemicals — the system will have adequate resistance to the types and levels of chemicals likely to be found in rainwater and soils normally encountered in civil engineering practice (see section 9).

Durability — the system will have a service life in excess of 50 years when installed in accordance with this Certificate (see section 11).

Agrément Certificate11/4821

Product Sheet 1

The BBA has awarded this Agrément Certificate to the company named above for the system described herein. This system has been assessed by the BBA as being fit for its intended use provided it is installed, used and maintained as set out in this Certificate.

On behalf of the British Board of Agrément

Date of First issue: 1 March 2011 Brian Chamberlain Greg Cooper

Head of Approvals — Engineering Chief Executive

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In the opinion of the BBA, the Rigofill Inspect Stormwater Management System, if used in accordance with the provisions of this Certificate, will meet or contribute to meeting the relevant requirements of the following Building Regulations:

The Building Regulations 2010 (England and Wales)

Requirement: H3(3) Rainwater drainage

Comment: The system can be used in a construction to meet this Requirement. See sections 5.1 to 5.10 of this Certificate.

Requirement: Regulation 7 Materials and Workmanship

Comment: The system is acceptable. See section 11 and the Installation part of this Certificate.

The Building (Scotland) Regulations 2004 (as amended)

Regulation: 8(1)(2) Fitness and durability of materials and workmanship

Comment: The use of the system satisfies the requirements of this Regulation. See sections 10 and 11 and the Installation part of this Certificate.

Regulation: 9 Building standards – constructionStandard: 3.6(a) Surface water drainage

Comment: The system can be used in a construction to satisfy this Standard, with reference to clauses 3.6.1(1)(2) to 3.6.5(1)(2). See sections 5.1 to 5.10 of this Certificate.

(1) Technical Handbook (Domestic). (2) Technical Handbook (Non-Domestic).

The Building Regulations (Northern Ireland) 2000 (as amended)

Regulation: B2 Fitness of materials and workmanship

Comment: The system is acceptable. See section 11 and the Installation part of this Certificate.Regulation: B3(2) Suitability of certain materials

Comment: The system is acceptable. See section 10 of this Certificate.Regulation: N5 Rain-water drainage

Comment: The system can be used in a construction to satisfy this Regulation. See sections 5.1 to 5.10 of this Certificate.

Construction (Design and Management) Regulations 2007Construction (Design and Management) Regulations (Northern Ireland) 2007

Information in this Certificate may assist the client, CDM co-ordinator, designer and contractors to address their obligations under these Regulations.See sections: 2 Delivery and site handling (2.3) and 13 Installation — Procedure (13.1) of this Certificate.

Non-regulatory Information

NHBC Standards 2011In the opinion of the BBA, the use of the Rigofill Inspect Stormwater Management System, in relation to this Certificate, is not subject to the requirements of these Standards.

GeneralThis Certificate relates to the Rigofill Inspect Stormwater Management System, consisting of polypropylene units, end plates, connection pieces and polyethylene pipe adapters.

This Certificate does not cover the collection or disposal of the surface water. Information relating to this can be obtained from the Certificate holder.

Regulations

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Technical Specification

1 Description1.1 The Rigofill Inspect Stormwater Management System (see Figure 1) consists of:• individual green polypropylene modular units, incorporating integral inspection tunnels, in two sizes (see Table 1)• black or green polypropylene horizontal and vertical connection pieces• green polypropylene end plates• black polyethylene pipe adapters• stainless steel screws for fixing end plates and adapters (if required).

Figure 1 Components

pipe adapters

multi-layer connector

modules

full block (800 mm x 800 mm x 660 mm) half block (800 mm x 800 mm x 350 mm)

DN 150 socket DN200 socket DN225 socket

single layer (horizontal) connector Snap-Ioc end plate

ancillary items

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Table 1 Characteristics of modular unit

Unit Full Block Half Block

Nominal dimensions (length x width x height) (mm) 800 x 800 x 660 800 x 800 x 350

Nominal volume (m³) 0.42 0.22

Nominal storage volume (m3) 0.40 0.21

Porosity (void ratio) (%) 95 95

Nominal mass (kg) 20 12

Ultimate compressive strengthat yield (kN·m–2)

Vertical loading on top faceLateral loading on side face

400130

Short-term deflection(1) Vertical loading on top faceLateral loading on side face

1 mm per 28 kN·m–2 1 mm per 9 kN·m–2

Estimated long-term deflection (ln)(2) (Ln)(3) (mm) 1.2017

(1) Applied load.(2) At up to 20 years at 20°C at 94 kN·m–2 load.(3) Time in hours.

1.2 The units are used in multiples in a block formation and are installed underground. The system manages run-off from impermeable surfaces by means of:• infiltration — ie as a soakaway to infiltrate water back into the ground• attenuation — ie as temporary storage for excess flows and to control outflow to streams and rivers• a combination of the above methods.

1.3 Connection to pipework may be effected either by pipe adapters inserted through or screwed to the polypropylene modular units or through the use of Rigofill Inspect chambers. All such connection methods are outside the scope of this Certificate. Self-tapping screws (where required) are supplied with the units.

1.4 Each assembled system is wrapped in either a permeable geotextile when used for infiltration or an impermeable geomembrane when used for attenuation. These are outside the scope of this Certificate. Information on the required specification for the geotextile and/or geomembrane can be obtained from the Certificate holder.

1.5 Adequate venting (using an air vent) to a manhole or to the atmosphere must be provided to the Rigofill Inspect structure to enable the system to accommodate its maximum storage volume. The designer should determine the number and size of vent pipe connections required. Air vent connections and associated pipework for use with this system are outside the scope of this Certificate.

2 Delivery and site handling2.1 The Rigofill Inspect Stormwater Management System units are supplied to site in packs of four full blocks (two layers of two units) to create a pallet 1.6 m x 0.8 m x 1.32 m deep, or eight half blocks (four layers of two units) to create a pallet 1.6 m x 0.8 m x 1.4 m deep. The modules are secured with two straps. Each pack carries a label bearing the product identification, employee reference, date of manufacture, article number and size.

2.2 Connection pieces are packed in sealed, polyethylene bags of 100. Each bag carries a label bearing the product identification and article number.

2.3 End plates and adapters are either individually packed and labelled with product identification and article number or packed in cardboard boxes bearing the same information.

2.4 The packs of units should be carefully placed on level ground and should not be stacked on site. Loose individual units should not be stored more than two modules high and should be secured against high winds.

2.5 The units contain an inhibitor to resist the effects of ultraviolet light for up to six months. However, prolonged exposure to direct sunlight should be avoided.

2.6 The units should not be stored near sources of direct heat, fuel bowsers, fuel tanks or solvents.

2.7 The units are resistant to the types of damage likely to occur during normal handling but should not be dropped or thrown, particularly in cold or frosty conditions. They should be stored in locations away from the possibility of impacts from vehicles and other construction plant.

Assessment and Technical Investigations

The following is a summary of the assessment and technical investigations carried out on the Rigofill Inspect Stormwater Management System.

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Design Considerations

3 General3.1 The Rigofill Inspect Stormwater Management System must be designed in accordance with the Certificate holder’s instructions. Guidance on the application of sustainable drainage systems (SUDS) for new developments, such as the Rigofill Inspect Stormwater Management System, can also be found in the Planning Policy Statement PPS25 Development and Flood Risk and The SUDS Manual C697 published by the Construction Industry Research and Information Association (CIRIA).

3.2 The system can be used for the control of run-off from impermeable surfaces in three main ways:• infiltration — water is collected in the units during rainfall and allowed to drain away by soaking into the

surrounding ground over a period of time• attenuation — water is collected in the units during rainfall and released at a reduced flow rate through a flow

control device into an appropriate outfall. This reduces peak flows in the watercourse, thereby minimising the risk of flooding

• combined — a combination of the above two systems.

3.3 Design of the appropriate system (see Table 2 and Figure 2) for a specific project must always be preceded by a detailed audit of the proposed site to establish: • existing factors and considerations applicable to the site• predicted factors relating to the site’s use following the planned development, and the parameters within which the

installation will be required to function• the type of function of application suggested by this audit.

Table 2 Site audit — factors/considerations.

Design aspect Considerations

Drainage area • area to be drained and rainfall data• the drainage area connected to a tank or soakaway should be as

small as is practical in order to limit silt accumulation• a system of several smaller tanks is preferable to one large tank• the use of upstream pre-treatment, such as silt traps or hydro-

dynamic separation, is recommended to minimise silts reaching the tank.

Space required (footprint) • available area for siting tank or soakaway.

Location • consider possible effects of infiltrating water on building foundations or other structures such as roads.

Site topography and stability • ground should be stable, especially where it is sloping; specialist assessment of soil and groundwater conditions may be necessary.

Subsurface soils, environmental sensitivity and groundwater • seasonal groundwater levels must be at least one metre below a soakaway; consider flotation forces if above base of a tank

• an appropriate risk assessment should be undertaken for areas which may contain contaminated soils, groundwater or are environmentally sensitive

• soil properties, eg CBR value, stiffness, infiltration potential, etc. should be considered.

Future site use • future possible changes in site use should be considered. For example, landscaped areas may be paved over to provide additional parking. Tanks or soakaways should be sited away from areas likely to be subject to further development.

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3.4 Once the project criteria have been established from the site audit, there are two main parts to the design process, namely hydraulic design and structural design (see sections 5 and 6).

Figure 2 Flowchart of the design process

Consider stormwater treatment

Is roofdrainagepresent?

YES

YES

YES

Considerrainwaterharvesting

Calculate tank size,filter and control

system requirements

Consideroverflowsolution

Determine design criteria:rainwater yield, non-potable

water usage

Rainwaterharvesting

ConsiderInfilration

NO

NO

NO

NO

YES

Is the soilinfiltration rate

suitable?

Is thegroundwater

levelappropriate?

Determinedesign criteria:Return period,rainfall data,

catchment data

Design soakawayto BRE Digest365 or CIRIAReport 156

Detaileddesign

Detaileddesign

Rigofill InspectInfiltrationSystem

Rigofill InspectAttenuation

System

Usestormwaterattenuation

Determininedesign criteria:Return period,rainfall data,

catchment data,discharge consent

Design flow control

Calculatestoragevolumerequired

Is development in aprotected groundwater

zone?

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4 Practicability of installationThe system is designed to be installed by a competent general builder, or a contractor, experienced with this type of system.

5 Hydraulic design Infiltration Calculation principles

5.1 Either the Construction Industry Research and Information Association (CIRIA) method, as given in Report 156 Infiltration Drainage — Manual of Good Practice, or the Building Research Establishment method, as given in BRE Digest 365 Soakaway Design, may be adopted.

5.2 A simplified approximate approach can be used on a very small site (eg a single-house development) where detailed site infiltration rate information may not be required nor available (see Table 3). From Approved Document H of the England and Wales Building Regulations, for areas up to 25 m2, a storage volume equal to 10 mm of rainfall over the area to be drained may be used. Beyond this size, design should be carried out in accordance with BS EN 752 : 2008 or BRE Digest 365. It is suggested in BS EN 752 : 2008 that a storage volume equal to 20 mm of rainfall over the area to be drained may be used. In Scotland, guidance for the design of single-house soakaways is given in Mandatory Standard 3.6, clause 3.6.5(1).(1) Technical Handbook (Domestic).

Table 3 Sizing guide for individual plot soakaways

Number of units Nominal storage volume (m³) Maximum impermeable catchment area to be drained (m²)

Full block Half block Full block Half block

1 0.4 0.2 25(1) 21.1(1)

2 0.8 0.4 40.2(2) 25(1)

3 1.2 0.6 60.3(2) 31.6(2)

4 1.6 0.8 80.4(2) 42.2(2)

5 2.0 1.1 100.6(2) 52.7(2)

10 4.0 2.1 201.1(2) 105.4(2)

(1) In accordance with Approved Document H.(2) In accordance with BS EN 752 : 2008, clause NA 4.4.8.

5.3 The design volumes and areas for trench or cuboid type installations when using the CIRIA or BRE approach can be found in Tables 4 and 5.

Table 4 Volumetric data per linear metre for 1 full size unit wide (0.8 m) trench configuration

Number of units deep

Storage volume(m3)

Surface area of ends (m2)

Surface area ofsides (m2)

Surface area ofbase (m2)

1 0.5 1.1 1.3 0.8

2 1.0 2.1 2.7 0.8

3 1.5 3.2 4.0 0.8

Table 5 Volumetric data for 3D usage one full size unit high (0.66 m)

Units long 2 units wide 4 units wide 8 units wide

Volume(m³)

Side and ends area

(m²)

Base area (m²)

Volume(m³)

Side and ends area

(m²)

Base area(m²)

Volume(m³)

Side and ends area

(m²)

Base area (m²)

1 0.8 3.2 1.3 1.6 5.3 2.6 3.2 9.5 5.1

2 1.6 4.2 2.6 3.2 6.4 5.1 6.4 10.6 10.2

5 4.0 7.4 6.4 8.0 9.5 12.8 16.1 13.8 25.6

10 8.0 12.7 12.8 16.1 14.9 25.6 32.2 19.1 51.2

25 20.1 28.6 32 40.2 30.8 64 80.4 35.0 128

100 80.4 108.2 128 160.9 110.3 256 321.8 114.6 512

5.4 For calculations, the size and volume of the units are given in Table 1. The total surface areas of the base and sides are required as water is absorbed through the geotextile soil interface. Storage volume is 95% of the total volume. As an example, using Table 4, for a typical linear trench 40 m long and 2 units deep, the volume is 1 m3 by 40 = 40 m3, the side area is 2.7 m2 by 40 = 108 m2, the end area is 2.1 m2 and the base area is 0.8 m2 by 40 = 32 m2.

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AttenuationCalculation principles 5.5 The anticipated run-off volume (A) from the site must be estimated. The most commonly used method for evaluating storm rainfall events in the UK is the Wallingford Procedure, by which the total rainfall level of storms over defined time periods ranging from five minutes up to 48 hours is assessed. The depth of water (mm) found can be multiplied by the catchment area to assess the size of attenuation systems and is normally based upon a two-hour storm of a return period appropriate for the catchment. The allowable discharge rate from the site to an appropriate outfall is established but will normally be set by the Environment Agency, the Scottish Environment Protection Agency or Planning Authorities. The outflow volume (B) to be discharged at this rate over the two-hour period is calculated and subtracted from the run-off volume (A–B). This defines the excess volume (C) to be stored in units constructed as an underground tank. The number of units needed to contain this excess is calculated on the basis that the storage volume is equal to 95% of the total volume of the tank.

Pipe connections5.6 Pipe connections are made to the units using either a pipe adapter or an integral Quadro-control inspection chamber. These both allow various sizes of pipe to be connected but are outside the scope of this Certificate (see Figure 3 for connection options).

5.7 When connecting pipes for storage applications (using a geomembrane), care must be taken to ensure a watertight seal. It is recommended that connections are made using a flange adapter. Adhesive or double-sided tape should be used between the geomembrane and flange adapter to ensure a watertight seal.

Manifold design5.8 The modules are manufactured to allow connection of pipes (via an adapter) up to 225 mm internal diameter, although connection of pipes up to 500 mm internal diameter is possible via a Quadro-control inspection chamber (outside the scope of this Certificate). If the anticipated design flow is greater than the hydraulic capacity of a single connection pipe, then the flow may be split between a number of pipes from an adjacent manhole. The system designer should ensure that the number and size of the pipe connections is sufficient to convey the anticipated design flow without restriction.

5.9 Where the system has an outflow or overflow connection, the flow will generally need to be controlled in order to comply with the discharge rate consent of the site (see Figure 5). A number of methods of flow control are available. Comparative features and performance of these flow control devices should be considered prior to selection. Such devices are outside the scope of this Certificate.

Outflow positioning and head calculations

5.10 The invert level of the outflow pipe should be flush with the bottom of the lowest unit to allow the tank to drain. The units may be laid to a gradient to assist free draining, but this will affect the loads that can be carried by the system as the units are manufactured to have the greatest strength in the vertical plane. Generally, gradients of

Figure 3 Pipe connection options

direct pipe connection up to 225 mm internal diameter viaaccess shaft. Rotatable through 360 degrees

Quadro-controlinspection chamber

direct pipe connection up to500 mm internal diameter viaQuadro-control inspection chamber

direct pipe connection up to 225 mminternal diameter via adapter socket

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1:100 should not be exceeded. Systems laid to a gradient are outside the scope of this Certificate. As the tank fills, a depth of water develops on the upstream side of the outflow control, creating a driving head to push the flow through the control device. For a tank with two layers of units, the maximum depth is 1.32 m when the units are full. For design purposes, the head used in calculations is taken as that at the invert level of the outflow device.

6 Structural design 6.1 Units can be placed under a wide variety of landscaped, amenity or trafficked areas. Design procedures for heavily-trafficked applications are outside the scope of this Certificate. If the proposed application of the product is in areas subject to high-intensity traffic, commercial vehicles or other heavy loads, advice should be sought from the Certificate holder.

6.2 The short-term ultimate compressive strength at yield for the units, as derived from independent test data, is 400 kN·m–2 for vertical loading on the top face and 130 kN·m–2 for lateral loading on the side face. A partial safety factor for materials (fm) of 2.75 for ultimate limit state and 1.5 for serviceability limit state should be applied to these values for a design life of 20 years. The short and long-term deflections are given in Table 1.

6.3 Creep tests indicate that the long-term deflection may be estimated from the following expression. This is valid for vertical loads up to 94 kN·m–2 for durations of up to 20 years at 20°C. In locations where settlement is not a concern, designs of up to 50 years can be considered:• deflection (mm) = 1.2017Ln (time in hours) – 2.309.

6.4 For small-scale applications such as soakaways for individual house roof drainage and where it is assumed that there will be no traffic loads, it is recommended that: • the minimum distance from the building should be 5 m• the maximum depth to the base of the units should be 5.1 m. This assumes a minimum value (which should be

confirmed from site investigation) for the angle of shearing resistance of the surrounding ground to be 29° and groundwater to be at least one metre below the base of the units

• the minimum cover depth over a completed installation to be 0.5 m to avoid damage by landscaping, agricultural or gardening equipment.

6.5 The units used for large-scale storage or infiltration must be designed to carry all loads that will be applied, including dead and imposed loads. Design parameters and estimated loads should be used to determine the maximum depth of installation and the maximum and minimum cover depths.

6.6 The criteria provided in Tables 6 and 7 can be used to design the units for installation below lightly- and non-trafficked areas. These design tables are only applicable in temperate climate conditions such as the UK. The following partial safety factors for loads have been applied: • ultimate limit state — vertical dead load (fdl) 1.40, earth pressure (horizontal) dead load (fep) 1.35, imposed live

load (fll) 1.60 • serviceability limit state — vertical dead load (fdl) 1.00, earth pressure (horizontal) dead load (fep) 1.00, imposed

live load (fll) 1.00.

Partial safety factors for materials (fm) of 2.75 for the ultimate limit state and 1.5 for the serviceability limit state have been applied. The system can be used for areas where greater loads are anticipated but these applications are outside the scope of this Certificate and specific advice should be sought from the Certificate holder.

Table 6 Maximum Installation depths (to base of units)(1)

Typical soil type Typical angle of shearing resistance �

Maximum depth of installation (to base of units) (m)

Groundwater level 1 m below groundlevel. Units installed in fully encapsulated

membrane liner (attenuation)

No groundwater present(below base of units)

– normal case

Trafficked area Non-trafficked area

Trafficked area Non-trafficked area

Stiff over consolidated clay, eg London clay 24° 3.0 3.0 4.4 4.6

Normally consolidated silty sandy clayeg alluvium, made ground

26° 3.0 3.1 4.8 4.9

Loose sand and gravel 30° 3.2 3.3 5.4 5.5

Medium dense sand and gravel 34° 3.4 3.5 6.3 6.4

Dense sand and gravel 38° 3.6 3.6 7.8 7.9

(1) The following assumptions apply: • trafficked areas are accessible only to cars and occasional refuse or emergency vehicles (typically once per week) • ground surface is horizontal • shear planes or other weaknesses/defects are not present in the soil structure • shear angle is confirmed by site survey • figures are calculated in accordance with CIRIA C680 for a design life of 20 years • where groundwater is present or the cover depth is greater than 4 m a detailed site survey and design assessment will be required; contact the

Certificate holder for further details.

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Table 7 Minimum cover depths(1)

Load conditions Minimum cover depth (m)

Non-trafficked areas, e.g. landscaped, amenity areas, etc. 0.5(2)

Car parks, vehicle mass ≤ 2500 kg 0.6

Car parks, occasional vehicle mass > 2500 kg(3) 0.8

(1) Assumes 27° load distribution through fill material and overlying surface of asphalt or block paving.(2) Minimum cover depth to avoid accidental damage from gardening/landscaping work.(3) Occasional trafficking by refuse collection trucks or similar vehicles (typically one per week).

6.7 For lightly-loaded applications, the bearing capacity of the underlying soils should not be exceeded by the system. Therefore settlement of the underlying soils should be negligible. On weak or compressible soils, the bearing capacity and settlement characteristics should be confirmed by a geotechnical engineer.

6.8 Care should be taken when the system is used for infiltration below trafficked areas and close to structures. It is important to ensure that the infiltrating water will not soften the soils or cause loss of fines and settlement.

6.9 When the units are wrapped in a geomembrane and placed below the groundwater table, flotation may occur. To prevent this, the weight of the soil over the top of the units must be greater than the uplift force caused by the units’ buoyancy in the water. This can be achieved with most types of fill if the depth of cover fill is equal to, or greater than, the depth of penetration of the units below groundwater level.

7 Geotextiles and geomembranes7.1 In infiltration applications a geotextile is wrapped around the system to prevent silt that may be contained in surface water run-off from contaminating the surrounding soil, in addition to reducing its permeability and to prevent surrounding soil from entering the units. In storage applications the purpose of the geotextile is to protect the geomembrane.

7.2 The selection of an appropriate geotextile for a specific Rigofill Inspect infiltration installation should be considered carefully, particularly with reference to the surrounding soil properties and required performance. Points to consider are:• pore size — this should be designed and specified to assist infiltration and prevent migration of fine soil particles• permeability and breakthrough head — the geotextile should not limit flow of water in the system, and should have

a similar or greater permeability than the surrounding ground• puncture resistance — the geotextile must be able to resist piercing by potentially sharp objects, eg stones in the soil• tensile strength — the geotextile should have sufficient strength to resist any imposed forces (eg from traffic).

7.3 The geotextile should be selected according to specific site conditions. Typical characteristics of a geotextile for infiltration systems are shown in Table 8. Geotextiles are outside the scope of this Certificate and the system designer should be satisfied that the chosen geotextile is suitable for the particular application. Specialist advice should be sought if surrounding soil characteristics exhibit a high degree of fines/low infiltration capacity and/or there is risk of damage from ground contaminants.

Table 8 Geotextile — typical specification

Material property (units) Test method Nominal value

CBR puncture resistance (N) BS EN ISO 12236 : 2006 1400

Water permeability(1) (m·s–1) BS EN ISO 11058 : 2010 110 x 10–3

Water flow normal to the plane (l·m–2·s–1) BS EN ISO 11058 : 2010 110

Elongation (%) MD CD BS EN ISO 10319 : 2008 40

55

Tensile strength (kN·m–1) MD CD BS EN ISO 10319 : 2008 8

8

Characteristic opening size (AOS)(2) (µm) EN ISO 12956 : 1999 130

Thickness (under 2 kPa) (mm) BS EN ISO 9863-1 : 2005 1.2

Mass per unit area (g·m–2) BS EN ISO 9864 : 2005 120

Fibre bonding Needled/thermally bonded

Material Polypropylene (PP)(3)

(1) Geotextile must be sufficiently permeable to allow free discharge of water and must be greater than the permeability of the surrounding soil.(2) The pore opening size should not be so large as to enable soil migration into the tank.(3) A white/ligh-coloured geotextile is recommended to assist with CCTV inspection.

7.4 In attenuation/storage applications where infiltration is not possible or permitted, a geomembrane is wrapped around the system to:• prevent release of attenuated/stored water to surrounding ground• prevent the inflow of pollutants from contaminated subsoil into the storage reservoir• prevent loss of storage volume due to inflow from groundwater and to prevent contamination of the groundwater.

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7.5 The specification and selection of the impermeable geomembrane must be correct for the proposed installation, to ensure it performs to the level required. It is essential that the specified material: • withstands the rigours of installation• resists puncture• resists multi-axial elongation stress and strains associated with settlement• resists environmental stress cracking• resists damage from ground contaminants• remains intact for the full design life.

Geomembranes less than 1 mm thick are unlikely to meet these criteria (except in shallow, domestic installations), and are not recommended for use with the system. For further details the Certificate holder’s advice should be sought. A specification for a typical polypropylene geomembrane is shown in Table 9.

Table 9 Typical geomembrane characteristics

Material property (units) Test method Nominal value

Thickness (mm) EN 1849-2 : 2001 1.0

Mass per unit area (g·m–2) EN 1849-2 : 2001 880

Tensile stress at break (MPa) BS EN ISO 527-3 : 1996 > 18

Elongation at break (%) BS EN ISO 527-3 : 1996 > 750

Tear propagation resistance (N·mm–1) DIN 53515 : 1977 (with cut) > 45

Piercing resistance (N) FTMS 101C > 150

Water absorption after 7 days (%) BS EN ISO 62 : 2008 < 0.2

Stress cracking resistance (h) ASTM D5397 > 1150

Dimensional changes after heat ageing (%) DIN 53377 : 2007 (1h/140ºC) ± 3

7.6 To ensure total impermeability, joints between adjacent sheets of impermeable geomembranes should be sealed correctly using proprietary welding techniques. The integrity of joints should be demonstrated by non-destructive testing, advice on which is given in CIRIA SP124 : 1996 Barriers, liners and cover systems for containment and control of land contamination.

8 Venting 8.1 Adequate venting must be provided to the structure, either through high level pipe connections between the units, through direct venting to the atmosphere or via Rigofill Inspect chambers which render separate venting systems unnecessary. Venting systems are outside the scope of the Certificate. Typical options are shown in Figure 4.

8.2 It is recommended that all air vent installations in storage applications (using a geomembrane) are made using a flange adapter. Adhesive or double-sided tape should be used between the geomembrane and flange adapter to ensure a watertight seal.

9 Resistance to chemicals 9.1 An assessment by the BBA indicates that the components of the system will resist the types and quantities of chemicals likely to be found in rainwater.

9.2 An assessment of the suitability of units for use on brownfield sites should be made only after a site investigation to determine the possibility of chemical contamination has been carried out. Particular care must be taken where acids and organic solvents are present in high concentrations. For further information contact the Certificate holder.

Figure 4 Ventilation options

connection between units Connection via Quadro-control inspection chamber

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10 Maintenance 10.1 The customer is responsible for maintenance. Recommendations for maintenance of SUDS systems are given in CIRIA C697. Integral inspection/maintenance tunnels in each unit allow the use of CCTV equipment for inspection and jetting or rodding equipment for maintenance.

10.2 For soakaways to individual houses, the only necessary maintenance of the system is to keep gullies clear of debris such as leaves.

10.3 For large installations or where the receiving waters are environmentally sensitive, a system of regular inspections should be established to prevent siltation of the system which, if allowed to develop, would reduce effectiveness. They should also be inspected after every major storm event.

10.4 It is recommended that a silt trap or upstream stormwater treatment is incorporated into the pipework at the inlet to the tank (see Figure 5). There must be a maintenance plan that ensures regular cleaning of the trap to ensure correct performance. Silt traps and upstream stormwater treatment for use with this system are outside the scope of this Certificate.

10.5 For all flow control devices it is good practice to incorporate access (via a manhole or similar) to the location of the pipe entry, orifice or vortex control. This will enable easy removal of any blockage. The flow control itself may be protected by a debris screen and may incorporate devices to allow drain down of the chamber should a blockage occur.

10.6 Paved surface areas above an installation should be inspected at the same time to ensure the units continue to provide the required structural support.

11 DurabilityThe structural properties of polypropylene used in the components of the system will deteriorate with time and should be taken into account at the design stage by the application of suitable safety factors. In the opinion of the BBA, the Rigofill Inspect Stormwater Management System, when used in accordance with this Certificate,

will have a life in excess of 50 years.

Installation

12 GeneralThe Rigofill Inspect Stormwater Management System should be installed in accordance with the Certificate holder’s installation instructions and relevant legislation.

13 Procedure 13.1 The hole or trench is excavated to the required depth, dimensions and levels. Sufficient area (300 mm minimum) must be left around the sides to allow access for plant to compact backfill material. The base of the excavation must be smooth and level without sharp drops or humps. Slopes must be cut to a safe angle or adequately supported and safe access must be provided to allow personnel to enter the excavation.

13.2 The base must be inspected for soft spots in the formation. Any present must be excavated and replaced with compacted granular fill material.

Figure 5 Typical attenuation layout including upstream stormwater treatment and flow control

Upstream stormwatertreatment

Flow controlRigofill Inspect system

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13.3 A 100 mm thick bedding layer of coarse sand or gravel is laid on the base and sides of the excavation. In an attenuation system, the protective geotextile fleece is laid.

13.4 The geomembrane (or geotextile, if an infiltration system) is laid over the bedding layer and up the sides of the excavation. The geomembrane is inspected for damage and all welds are tested as required. Joints between adjacent sheets of impermeable membrane should be sealed correctly using proprietary techniques with a minimum lap of 50 mm. Generally jointing with tape is not recommended as the system becomes reliant on the mechanical properties of the tape to maintain its integrity.

13.5 The units are installed in accordance with the installation schedule for correct orientation. The units are arranged so that the tunnels are in line, giving access through the system. For single-layer applications, horizontal connection pieces are used and for multiple layer systems, multi-layer connection pieces are used.

13.6 The ends of the tunnel are fitted with the appropriate end plate.

13.7 The geotextile or geomembrane enclosure of the base, sides and top of installation, including protective geotextile (where required), is completed. Geomembranes should be welded with double seams. The geomembrane is inspected for damage and all welds are tested as required.

13.8 Inlet and outlet connections are made to the installation using pipe adapters.

13.9 The installation is backfilled with type 1 or 2 sub-base or Class 6P (side fill only) selected granular material in accordance with the Manual of Contract Documents for Highway Works, Volume 1. The backfill is compacted in 150 mm thick layers. The side fill and the first 300 mm of compacted material above the tank should be compacted using laminar working devices only.

13.10 A 100 mm thick coarse sand or gravel protection layer should be placed over the top of the units that are wrapped in either a geotextile (infiltration system) or a geomembrane with protective geotextile (attenuation system). Backfilling is continued with:• trafficked areas (eg car parks) — type 1 or 2 sub-base material compacted in 150 mm layers in accordance with

the Manual of Contract Documents for Highway Works, Volume 1. Compaction of the first 300 mm of cover should be carried out using laminar working devices. Thereafter compaction plant over the top of the system should not exceed 2300 kg per metre width

• landscaped and non-trafficked areas — selected as-dug material with size of pieces less than 75 mm, compacted to 90% maximum dry density

• vehicle movement over the top of the system should be performed in straight passes only.

13.11 The pavement construction or landscaping is completed over the system.

13.12 It is recommended that CCTV inspection of the system is carried out following the installation to ensure that the membrane/geotextile liner has been installed correctly and has not been punctured or torn during construction. This inspection can also serve to ensure that no debris has entered the storage volume.

Technical Investigations

The following is a summary of the technical investigations carried out on the Rigofill Inspect Stormwater Management System.

14 Tests Tests were carried out on the system to determine: • long-term and short-term resistance to loading • volumetric capacity.

15 Investigations15.1 The manufacturing process was examined including the method adopted for quality control, and details obtained on the quality and composition of the material used.

15.2 An assessment of the system was made in relation to: • material properties • design procedures • geotextile and geomembrane specifications.

15.3 A site visit was made to assess the practicability and ease of installation and connection.

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BibliographyASTM D 5397 : 1999 Standard Test Method for Evaluation of Stress Crack Resistance of Polyolefin Geomembranes Using Notched Constant Tensile Load Test

BS EN 752 : 2008 Drain and sewer systems outside buildings

BS EN ISO 62 : 2008 Plastics — Determination of water absorption

BS EN ISO 527-3 : 1996 Plastics — Determination of tensile properties — Test conditions for films and sheets

BS EN ISO 9863-1 : 2005 Geosynthetics — Determination of thickness at specified pressures — Single layers

BS EN ISO 9864 : 2005 Geosynthetics — Test method for the determination of mass per unit area of geotextiles and geotextile-related products

BS EN ISO 10319 : 2008 Geotextiles — Wide-width tensile test

BS EN ISO 11058 : 2010 Geotextiles and geotextile-related products — Determination of water permeability characteristics normal to the plane, without load

BS EN ISO 12236 : 2006 Geosynthetics— Static puncture test (CBR-test)

DIN 53377 : 2007 Testing of plastic films; Determination of dimensional stability

DIN 53515 : 1977 Determination of tear strength of rubber, elastomers and plastic film using Graves angle test piece with nick

EN 1849-2 : 2001 Flexible sheets for waterproofing— Determination of thickness and mass per unit area — Plastic and rubber sheets for roof waterproofing

EN ISO 12956 : 1999 Geotextiles and geotextile-related products— Determination of the characteristic opening size

FTMS 101C : Method 2065 Puncture test

Manual of Contract Documents for Highway Works, Volume 1 Specification for Highway Works, Series 900 Road pavements — bituminous bound materials

Manual of Contract Documents for Highway Works, Volume 2 Notes for Guidance on the Specification for Highway Works, Series 900 Road pavements — bituminous bound materials

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Conditions of Certification

16 Conditions16.1 This Certificate:• relates only to the product/system that is named and described on the front page• is granted only to the company, firm or person named on the front page — no other company, firm or person may

hold or claim any entitlement to this Certificate• is valid only within the UK• has to be read, considered and used as a whole document — it may be misleading and will be incomplete to be

selective• is copyright of the BBA• is subject to English law.

16.2 Publications and documents referred to in this Certificate are those that the BBA deems to be relevant at the date of issue or re-issue of this Certificate and include any: Act of Parliament; Statutory Instrument; Directive; Regulation; British, European or International Standard; Code of Practice; manufacturers’ instructions; or any other publication or document similar or related to the aforementioned.

16.3 This Certificate will remain valid for an unlimited period provided that the product/system and the manufacture and/or fabrication including all related and relevant processes thereof:• are maintained at or above the levels which have been assessed and found to be satisfactory by the BBA• continue to be checked as and when deemed appropriate by the BBA under arrangements that it will determine• are reviewed by the BBA as and when it considers appropriate.

16.4 In granting this Certificate, the BBA is not responsible for:• the presence or absence of any patent, intellectual property or similar rights subsisting in the product/system or any

other product/system• the right of the Certificate holder to manufacture, supply, install, maintain or market the product/system• individual installations of the product/system, including the nature, design, methods and workmanship of or related

to the installation• the actual works in which the product/system is installed, used and maintained, including the nature, design,

methods and workmanship of such works.

16.5 Any information relating to the manufacture, supply, installation, use and maintenance of this product/system which is contained or referred to in this Certificate is the minimum required to be met when the product/system is manufactured, supplied, installed, used and maintained. It does not purport in any way to restate the requirements of the Health & Safety at Work etc Act 1974, or of any other statutory, common law or other duty which may exist at the date of this Certificate; nor is conformity with such information to be taken as satisfying the requirements of the 1974 Act or of any statutory, common law or other duty of care. In granting this Certificate, the BBA does not accept responsibility to any person or body for any loss or damage, including personal injury, arising as a direct or indirect result of the manufacture, supply, installation, use and maintenance of this product/system.

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British Board of Agrément tel: 01923 665300Bucknalls Lane fax: 01923 665301Garston, Watford e-mail: mail@bba.star.co.ukHerts WD25 9BA website: www.bbacerts.co.uk©2011