PUBLIC REVIEW DRAFT DRAFT UGANDA STANDARD  
  DUS EAS 426-2 
First  Edition  
2016-mm-dd 
 
 Reference number  
DUS EAS 426-2: 2006 
© UNBS 201 6 
  
Concrete pipes and ancillary concrete products — Part 2: 
Specification for unreinforced and reinforced concrete 
manholes and soakaways  
 PUBLIC REVIEW DRAFTDUS EAS 426-2: 2006 
ii                © UNBS  2016  - All rights reserved 
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 2016 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior written 
permission from UNBS. 
Requests for permission to reproduce this document should be addressed to 
The Executive Director 
Uganda National Bureau of Standards 
P.O. Box 6329 
Kampala 
Uganda 
Tel: 256 417 333 2 50/1/2/3 
Fax: 256 414 286 123 
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  
 PUBLIC REVIEW DRAFTDUS EAS 426-2:2006 
© UNBS  2016 - All rights reserved                iii National foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade, Industry and 
Cooperatives established under Cap 327, of the Laws of Uganda, as amended.  UNBS is mandated to co-
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT Agreement of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of representatives of 
consumers, traders, academicians, manufacturers, government and other stakeholders. 
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
This Draft Uganda Standard, DUS EAS 426-2: 2006 , Concrete pipes and ancillary concrete products — Part 
2: Specification for unreinforced and reinforced concrete manholes and soakaways,  is identical with  and has 
been reproduced from an East African Standard, EAS 426-2 : 2006, Concrete pipes and ancillary concrete 
products — Part 2 : Specification for unreinforced and reinforced concrete manholes and soakaways,  and is 
being proposed for adoption as a Uganda Standard. 
This standard was developed by the Building and civil engineering Standards Technical Committee (UNBS/TC 
3). 
Wherever the words, “ East African Standard" appear, they should be replaced by "Uganda Standard." 
 
  PUBLIC REVIEW DRAFTEAS 426-2:2006 
ICS 91.140.80 
HS 6810.20.00 
HS 6810.91.00 
  
 
© EAC 2006 First Edition 2006 
 
  
  
EAST AFRICAN STANDARD 
 
Concrete pipes and ancillar y concrete products — 
Part 2:  
Specification for unreinforced and reinforced concrete manholes 
and soakaways  
 
 
 
   
 
   
 
 
 
 
 
 
  
 
 
 
 
EAST AFRICAN COMMUNITY  
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
ii © EAC 2006 — All rights reserved  
Table of contents 
 
1 Scope ........................................................................................................................ ..................1 
2 Normative references......................................................................................................... ..........1 
3 Terms and definitions........................................................................................................ ...........2 
4 Symbols...................................................................................................................... .................3 
5 General requirements ......................................................................................................... .........3 
5.1 Application................................................................................................................ ...........3 
5.2 Concrete (4.2) ............................................................................................................. ........3 
5.3 Finish (4.3.2) ............................................................................................................. ..........5 
5.4 Geometrical characteristics (4.3.3). .....................................................................................6 
5.5 Crushing strength of chamber and shaft units (4.3.5)........................................................12 
5.6 Watertightness of vertical units (4.3.8) ..............................................................................12 5.7 Steps (4.1)................................................................................................................ .........12 
6 Special requirements ......................................................................................................... ........12 
6.1 Reinforced concrete units and components (5.2) ..............................................................12 6.2 Vertical strength of cover, reducing and landing slabs and corbel slabs (5.2.4).................13 
7 Conformity evaluation ........................................................................................................ ........17 
7.1 Application................................................................................................................ .........17 
7.2 Finish ..................................................................................................................... ...........17 
7.3 Geometrical characteristics ...............................................................................................1 7 
7.4 Vertical strength of landing slabs and corbel slabs............................................................17 
8 Marking...................................................................................................................... ................17 
Annex B (normative) Standards relevant to EAS 418.........................................................................19 
Annex C (normative) Surface void test ... ....................................................................................... .....20 
Annex D (normative) Dimensional tests ...... .................................................................................... ...21 
Bibliography ................................................................................................................... ....................23 
 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved iii  
Foreword 
 
Development of the East African Standards has been necessitated by the need for harmonizing requirements governing quality of products and services in East Africa. It is envisaged that through 
harmonized standardization, trade barriers which are encountered when goods and services are 
exchanged within the Community will be removed.   
In order to achieve this objective, the Partner States in the Community through their National Bureaux 
of Standards, have established an East African Standards Committee.  
The Committee is composed of representatives of the National Standards B odies in Partner States, 
together with the representatives from the private sectors and consumer organizations. Draft East 
African Standards are circulated to stakeholders through the National Standards Bodies in the Partner 
States. The comments received are discussed and incorporated before finalization of standards, in accordance with the procedures of the Community.  
East African Standards are subject to review, to keep pace with technological advances. Users of the 
East African Standards are therefore expected to ensu re that they always have the latest versions of 
the standards they are implementing.  
 
© East African Community 2006 — All rights reserved
* 
East African Community  P O Box 1096  
Arusha 
 
Tanzania  
Tel: 255 27 2504253/8 
Fax: 255-27-2504481/2504255 
E-Mail: eac@eachq.org  
Web: www.each.org 
[Based on 5911-3:2002] 
 
 
 
                                                 
* © 2005 EAC — All rights of exploitation in any form and by any means reserved worldwide for EAC Partner States’ NSBs.  
 PUBLIC REVIEW DRAFTPUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  1  
Concrete pipes and ancillar y concrete products — 
Part 2:  
Specification for unreinforced and reinforced concrete manholes 
and soakaways 
 
 
1 Scope  
 
EAS 418 specifies requirements and describes test methods for precast concrete manholes of 
circular, rectangular (with or without chamfered or rounded corners) or elliptical cross-section, 
unreinforced, steel fibre and reinforced, with nominal sizes or nominal lengths not exceeding DN 1250 or LN 1250, respectively. The intended use of EAS 418 is to permit access to, and to allow aeration 
of, drain or sewer systems for the conveyance of sewage, rainwater and surface water under gravity or occasionally at low head of pressure, mainly installed in areas subjected to vehicular and/or pedestrian traffic. 
 
This part of EAS 426 specifies complementary requirements to those in EAS 418 for unreinforced and reinforced concrete manholes of circular and rectangular cross-section (with or without chamfered or 
rounded corners), as provided for in that European Standard, i.e. units with nominal sizes or nominal 
lengths not exceeding DN 1250 or LN 1250, respectively. Full requirements for unreinforced and reinforced concrete manholes with nominal sizes greater than DN 1250, but not exceeding DN 3000, 
are also specified. The manholes are intended to be installed in carriageways of roads (including 
pedestrian streets), hard shoulders and parking areas for all types of road vehicles, though provision is also made for units subject to lighter traffic load ing. Requirements for soakaways, landing slabs and 
corbel slabs are also specified.  Steel fibre concrete manholes are not manufactured in the United Kingdom and so have been 
excluded from this part of EAS 426. 
 EN 752-2, -3 and -4, EN 1295-1 and EN 1610 deal with the planning, design, installation and testing of drains and sewers.  
2 Normative references 
 
The following referenced documents are indispensable for the application 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. 
 
BS 146 , Specification for blastfurnace cements with strength properties outside the scope of EAS 18-
1 
 
BS 3123 , Specification for spring calipers and spring dividers 
 
BS 3892-1 , Pulverized-fuel ash — Part 1: Specification for pulverized-fuel ash for use with Portland 
cement 
 
BS 4027 , Specification for sulfate-resisting Portland cement 
 BS 4035 , Specification for linear measuring instruments for use on building and civil engineering 
constructional works — Steel measuring tapes, steel bands and retractable steel pocket rules  
BS 4449 , Specification for carbon steel bars for the reinforcement of concrete 
 
BS 4482 , Specification for cold reduced steel wire for the reinforcement of concrete 
 BS 4483 , Steel fabric for the reinforcement of concrete EAST AFRICAN STANDARD PUBLIC REVIEW DRAFTEAS 426-2:2006  
2 © EAC 2006 — All rights reserved  
BS 4484-1 , Specification for measuring instruments for constructional works — Part 1: Metric 
graduation and figuring of instruments for linear measurement 
 BS 6699 , Specification for ground granulated blastfurnace slag for use with Portland cement 
 
EAS 18-1 , Cement — Part 1: Composition, specificatio ns and conformity criteria for common cements 
 
BS EN 934-2 , Admixtures for concrete, mortar and grout — Part 2: Concrete admixtures — 
Definitions, requirements, conformity, marking and labelling 
 
BS EN 1008 , Mixing water for concrete — Specification for sampling, testing and assessing the 
suitability of water, including water recovered from processes in the concrete industry, as mixing 
water for concrete 
 
EAS 418 , Concrete manholes and inspection chambers, unreinforced, steel fibre and reinforced 
 BS EN 12620 , Aggregates for concrete 
 
BS EN 13101 , Steps for underground man entry chambers — Requirements, marking, testing and 
evaluation of conformity  
 
3 Terms and definitions 
 
For the purpose of this part of EAS 426, the terms and definitions given in EAS 418 and the following 
apply. 
 
3.1 
cementitious content amount of cement plus any pozzolanic or latent hydraulic addition in the concrete mix 
 
3.2 
corbel slab component without a joint or installed step incorporating a load-bearing overhang, used to adjust the 
total height of a structure and/or to accommodate an appropriate frame or cover 
 
NOTE See Figure 1. 
 
 Dimensions in mm  
 
Figure 1 — Use of corbel slabs in conjunction with double steps or ladder 
 3.3 
landing slab 
component forming an intermediate horizontal platform within a manhole and having an access 
opening 3.4 manufacturing diameter 
diameter of a circular unit that a manufacturer seeks to achieve PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  3 3.5 
manufacturing size 
dimensions of a rectangular unit that a manufacturer seeks to achieve  
3.6 
soakaway 
vertical chamber of circular cross-section, perforated to allow the passage of water and with or without 
an access shaft 
 
3.7 
square or rectangular opening 
square or rectangular shaped access hole whose corners may be relieved by nominal 75 mm × 75 mm chamfers, or by nominal 75 mm radii 
 
4 Symbols 
 
The meanings of symbols used in this part of EAS 426 shall be as given in Table 1, together with those in EAS 418, Table 2.  
Table 1 — Symbols 
 
Symbol  Meaning  Unit Reference 
hs  Height of studs on straightness gauge  mm  D.3.2 
h’  Effective height minus 0.03 m m  D.3.2 
 
5 General requirements 
 
NOTE The numbers in brackets after subclause headings are the corresponding subclause numbers in EAS 418. 
 
5.1 Application 
 
For units with nominal size or nominal length not  exceeding DN 1250 or LN 1250, respectively, the 
requirements of this part of EAS 426 shall be in addition to those specified in EAS 418 and for the 
purposes of the latter the reference specifications shall be those listed in Annex B of this Standard. For manholes with nominal sizes greater than DN 1250, landing slabs, corbel slabs and soakaways the requirements of EAS 418 shall also apply, except as otherwise required by, or stated in, this part 
of EAS 426. 
 
5.2 Concrete (4.2) 
 
5.2.1 Composition 
 5.2.1.1 Types of cement 
 
The cement (see EAS 418:2002, 4.1) shall either: 
 
a) be factory-produced by the cement manufacturer and conform to one of the following Standards as 
appropriate: 
 
Type of cement  Standard CEM I  EAS 18-1 
CEM II/B-V  EAS 18-1 
BIII/B  BS 146 
Sulfate-resisting Portland  BS 4027; or 
 b) consist of a combination of cement conforming  to CEM I as specified in EAS 18-1 and an addition 
in the form of ground granulated blastfurnace slag (ggbs) or pulverized-fuel ash (pfa) in the 
proportions specified in 5.2.1.2 ", to be included as part of the concrete mix by simultaneously 
combining them with the other concrete materials at the concrete mixer. 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
4 © EAC 2006 — All rights reserved In all cases where combinations of cement conforming to CEM I as specified in EAS 18-1 and ggbs or 
pfa are used, the relevant proportion of ggbs or pfa shall be fully documented in the production 
records. 
 
5.2.1.2 Cementitious content 
 
The fully compacted concrete shall have a minimum cementitious content of not less than the relevant 
amount shown in Table 2. The composition/specificat ion of cement groups shall be as shown in Table 
3. 
 
Table 2 — Cementitious content a 
 
Classb Aggregate 
carbonate rangec Cement or 
combination group  Minimum cement or 
combination content 
kg/m3 Maximum w/c 
ratio  
DC-2  A, B, C  1, 2, 3  340  0.45 
A  2a  400  0.40 
A  2b, 3  380  0.45 DC-3  
B, C  2, 3  340  0.45 
DC-3*  B  2, 3  380  0.45 
DC-3**  C  2, 3  380  0.45 
A  2a  400  0.35 
A  2b, 3  400  0.40 
A  2, 3  380  0.33 
B, C  2, 3  380  0.45 DC-4  
B, C  2, 3  360  0.40 
B  2, 3  380  0.33 DC-4*  
B  2, 3  400  0.40 
C  2, 3  380  0.33 DC-4**  
C  2, 3  400  0.40 
A  2b, 3  380  0.33 
A  2b, 3  400  0.40 
B  3  400  0.40 
B, C  3  360  0.40 DC-4m  
B, C 3 380 0.45 
DC-4m*  B  3  380  0.33 
C  3  380  0.33 DC-4m** 
C  3  400  0.40 
a The table is consistent with the provisions of BS 8500-1:2002 and BRE Special Digest 1 [1] insofar as they relate to precast 
concrete pipeline systems, except that the maximum water content (w/c) ratio is limited to 0.45 in accordance with EAS 
418:2002, 4.2.4.2 . 
 
b The class designations are those for design chemical class (DC-class) in BS 8500-1:2002, Table A.15. Where there is more 
than one option in a class the choice is at the manufacturer’s discretion. 
 
c See BRE Special Digest 1 — Part 4, Table 4.  
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  5  
Table 3 — Cement groupsa 
 
Type (see 5.2.1.1 ) Designation Standard  Grouping with 
respect to 
sulfate 
resistance 
Portland cement CEM I BS EN 197-1  1 
Portland fly ash cements CEM II/B-Vb BS EN 197-1 2ac 
Sulfate-resisting Portland cement SRPC BS 4027  3 
Blastfurnace slag cementse BIII/Bd BS 146  2be 
Combinations conforming to BS 8500-2:2002, Annex A manufactured in the concrete mixer from Portland cement and pfa or ggbs:     
CEM I cement conforming to BS EN 197-1 with a mass fraction of 6 % to 20 % of combination of pfa conforming to BS 3892-1 CIIA-V  BS 8500-2  1 
CEM I cement conforming to BS EN 197-1 with a mass fraction of 21 % to 35 % of combination of pfa conforming 
to BS 3892-1 CIIB-Vb BS 8500-2  2ac 
CEM I cement conforming to BS EN 197-1 with a mass fraction of 36 % to 55 % of combination of pfa conforming 
to BS 3892-1 CIVB-Vb BS 8500-2  2af 
CEM I cement conforming to BS EN 197-1 with a mass fraction of 6 % to 35 % of combination of ggbs conforming to BS 6699 CII-S
g BS 8500-2  1 
CEM I cement conforming to BS EN 197-1 with a mass 
fraction of 36 % to 65 % of combination of ggbs conforming 
to BS 6699 CIIIA BS 8500-2  1 
CEM I cement conforming to BS EN 197-1 with a mass fraction of 66 % to 80 %e of combination of ggbs 
conforming to BS 6699 CIIIBd BS 8500-2 2be 
a The table is consistent with BS 8500-1:2002, Table A.17 and BS 8500-2:2002, Table 1. 
b Where the proportions for sulfate resistance are required, i.e. not less than 25 % and not more than 40 % pfa, add to the 
 abbreviation “+SR”. 
c Provided the pfa content is a mass fraction of not less than 25 % of cement or combination. Where it is less than 25 %, 
 the cement of combination falls within group 1. 
d Where the proportions for sulfate resistance are required (see e), add to the abbreviation “+SR”. 
e Where the alumina content of the slag exceeds 14 %, the tricalcium aluminate content of the Portland cement fraction 
 should not exceed 10 %. Where this is not the case, the grouping with respect to sulfate resistance is “1”. 
f Provided the pfa content is a mass fraction of not more than 40 % of cement or combination. Where it exceeds 40 %, no 
 guidance is provided. 
g Where necessary, this class can be subdivided into CIIA-S (6 % to 20 % ggbs) and CIIB-S (20 % to 35 % ggbs). 
 
5.2.1.3 Mixing water (4.1) 
 
Mixing water for concrete shall conform to BS EN 1008. 
 
NOTE EN 1008:2002, 3.1 specifies that potable water does not need testing. 
 
5.3 Finish (4.3.2) 
 
5.3.1 Surface voids 
 
With the exception of the external edges of slabs and of adjusting units and of corbel slabs, when tested in accordance with Annex C surfaces of units and components shall be free from voids that 
permit diametrically opposite points of the rim of the gauge to touch the surface of the unit or 
component simultaneously. 
 Units and components exhibiting any surface void greater than 12 mm deep shall be deemed not to 
conform to this part of EAS 426. 
 
NOTE Voids up to and including 12 mm deep may be made good by the manufacturer — see EAS 418, 4.3.2 . 
  PUBLIC REVIEW DRAFTEAS 426-2:2006  
6 © EAC 2006 — All rights reserved 5.4 Geometrical characteristics (4.3.3) 
 
5.4.1 General 
 
Subject to the requirements of this clause, the dimensions and thickness of units and components shall conform to those stated in the factory documents.  5.4.2 Nominal sizes 
 
NOTE 1 Nominal size is defined in EAS 418:2002, 3.1.16 as a numerical designation of the size of a component within a 
structure, which is a convenient integer approximately equal to the manufacturing dimension in millimetres; for a circular unit  it 
is the internal diameter (DN), and for a unit having a rectangular or elliptical internal shape it is the internal length/width  
(LN/WN). 
 The nominal sizes of circular and rectangular vert ical units and tapers for use with them, shall be 
those given in Table 4 and Table 5, respectively. Steps shall not be permitted in DN 900 shafts or 
associated components. 
 
NOTE 2 DN 900 units are intended only to be used as a winch shaft because, if fitted with steps or a ladder, the clear space 
to the back of the shaft would be less than the 900 mm as recommended in the HSE publication, “Safe work in confined spaces” [2] and in BS EN 752-3:1997, Annex NB. Equally, ladders should not be fitted to DN 1050 units. 
 
Table 4 — Nominal sizes, internal manufacturing diameters and tolerances of circular units 
 
Limits of internal manufacturing diameter  Nominal size of 
chamber and shaft 
units  
DN Minimum  
mm  Maximum  
mm  Tolerance on actual diameter 
from manufacturer’s stated 
diametera 
mm 
900  900  950  ±8 
1050  1 050  1 100  ±8 
1200  1 200  1 250  ±9 
1500  1 500  1 550  ±11 
1800  1 800  1 850  ±12 
2100  2 100  2 150  ±14 
2400  2 400  2 450  ±15 
2700  2 700  2 750  ±15 
3000  3 000  3 050  ±15 
NOTE 1 Base units have not been commonly used in the United Kingdom — see Note 2 to Figure 1 in EAS 418:2002. It is not envisaged that any will be available in nominal sizes greater than DN 1250. 
NOTE 2 Capping units are not manufactured in the United Kingdom. 
 
a See 3.4 . 
 
5.4.3 Internal manufacturing diameter and manufacturing size of vertical units 
 
The internal manufacturing diameters and manufacturing sizes of circular and rectangular vertical units shall not be outside the limits given in Table 4 and Table 5, respectively.  
Table 5 — Nominal sizes, internal manufacturing sizes and tolerances of rectangular units 
 
Nominal size  Limits of internal manufacturing size  
LN/WN Minimum  
mm Maximum  
mm Tolerance on actual size from 
manufacturer’s stated size a 
mm 
900/675 925/700 900/675 ±6 
1200/675 1 250/700 1 200/675 ±6 
1200/750 1 250/800 1 200/750 ±7 
a See 3.4. 
 
5.4.4 Shape, size and position of openings in slabs, adjusting units and corbel slabs  
The shape, size and position of openings in slabs, adjusting units and corbel slabs shall be in accordance with Table 6 and Table 7. The tolerance on the sizes of openings in cover slabs, adjusting 
units and corbel slabs shall be mm. 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  7 NOTE It is permissible for the vertical face(s) of an opening to be cast with a nominal release angle away from the opening. 
 
Table 6 — Shape, size and position of openings in cover slabs, adjusting units and corbel 
slabs 
 
Opening configuration  Type of unit  Shaft or chamber nominal size 
DN or LN/WN Size [mm]  Location  Reference  
900 600× 600 
900 675× 675 Central 
1050 600× 600 
1050 675× 675 Eccentric 
1050 750× 750 Central 
1200 and 1500 675× 675 
1200 and 1500 750× 600 Eccentric 
1200 and 1500 1200 ×675 Central 
1800, 2100, 2400, 2700 and 3000 675× 675 
1800, 2100, 2400, 2700 and 3000 750× 600 Cover slab — 
circular 
1800, 2100, 2400, 2700 and 3000 1200 ×675 Eccentric Figure 2 
900/675 
1200/675 Cover ― 
rectangular 
1200/750 600× 600 Eccentric Figure 3 
― 600× 600 
― 675× 675 
― 750× 600 
― 750× 750 Adjusting unit 
― 1200 ×675 Central Figure 4 
Corbel slab ― 600× 600 Eccentric Figure 5 
NOTE 1 The sizes of the openings are generally consistent with the safety guidelines given in the HSE publication “Safe 
work in confined spaces” [2] and in BS EN 752-3:1997, Annex NB. 
 NOTE 2 In EAS 426-200 “adjusting units” and “corbel slabs” were both described as “cover frame seating rings”. 
 
 
Table 7 — Shape, size and position of openings in reducing and landing slabs 
 
Opening configuration  Type of unit or component  Chamber nominal size 
DN Shaft nominal 
size 
DN Size  mm Location  Reference
Reducing slab  1200 to 3000  900  900  Eccentric  Figure 6 
 1500 to 3000  1050  1050  Eccentric  
 1800 to 3000  1200  1200  Eccentric  
Landing slab  1500 to 3000  —  900  Eccentric  Figure 7 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
8 © EAC 2006 — All rights reserved  
Dimensions in mm 
 
 
 
Figure 2 — Openings in circular cover slabs 
 
Dimensions in mm 
 
Figure 3 — Openings in rectangular cover slabs 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  9 Dimensions in mm 
 
 
 
Figure 4 — Typical adjusting unit 
 
 
Dimensions in mm  
 
 
Figure 5 — Typical corbel slabs 
 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
10 © EAC 2006 — All rights reserved Dimensions in mm  
 
 
Figure 6 — Typical reducing slabs 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  11 
 
 
Figure 7 — Typical landing slabs 
 
5.4.5 Sizes and number of apertures in soakaways 
 
Soakaway chamber units shall have holes not less than 45 mm and not greater than 80 mm in diameter, or slits not less than 15 mm or not greater than 25 mm wide, spaced around the 
circumference. The number and area of holes or slits shall be such that there is a minimum aperture 
area in each unit of 50 000 mm
2 per metre of effective height per metre of nominal size of chamber. 
 
5.4.6 Dimensional tolerances 
 5.4.6.1 Tolerances on the internal diameter of circular vertical units 
 
The tolerances on the internal manufactured diameter of circular vertical units and related tapers shall 
be ±(3 + 0.005DN) mm (rounded to the nearest millimetre), limited to ±15 mm (see Table 4). No 
individual measurement, measured in accordance with  D.1, shall be outside the specified limits. 
 
5.4.6.2 Tolerances on the internal size of rectangular vertical units 
 
The tolerances on the internal manufactured size of rectangular vertical units shall be ±(3 + 0.005WN) mm (rounded to the nearest millimetre), limited to ±15 mm (see Table 5). No individual measurement, 
measured in accordance with D.1, sh all be outside the specified limits. 
 5.4.6.3 Tolerance on the thickness 
 
Any value of thickness measured in accordance with D.2 shall be not less than the value stated in the 
factory documents. 
 
5.4.6.4 Deviation from straightness 
 
When measured in accordance with D.3, for the internal surface of a vertical unit having an effective 
height greater than 0.5 m, both ends of the gauge shall not make contact with the surface of the unit when using Edge X and the two studs shall be in contact simultaneously when using Edge Y. 
 
NOTE See Figure D.1. PUBLIC REVIEW DRAFTEAS 426-2:2006  
12 © EAC 2006 — All rights reserved  
5.4.6.5 Squareness of ends 
 
Vertical units shall be capable of being jointed with their relevant axes coincident. For circular 
chamber and shaft units this requirement shall apply in any orientation. 
 
NOTE Squareness of ends is significant only to the extent that it relates to type of sealing material and to the performance 
of a joint assembly. 
 
5.5 Crushing strength of chamber and shaft units (4.3.5) 
 
NOTE Strength class is defined in EAS 418, 3.1.21 as the minimum crushing load in kilonewtons per metre, divided by one 
thousandth of either a unit’s nominal size (DN) or nominal length (LN). 
 
The strength classes and corresponding minimum crushing loads of circular and rectangular chamber 
and shaft units shall be in accordance with Table 8. 
 
For the purposes of carrying out the test described in EAS 418, A.4.1 on chamber and shaft units 
greater than DN 1250, the maximum width of bearing strips shall be 150 mm for units not greater than DN 2500 and 200 mm for larger units. 
 
Table 8 — Strength classes and corresponding mi nimum crushing loads for circular and 
rectangular chamber and shaft units 
 
Nominal size  
DN Nominal length  
LN Single strength class  Minimum crushing load Fn 
(rounded up to nearest kN/m) 
—  900  30  27 
—  1200  25  30 
900  —  30  27 
1050  —  30  32 
1200  —  25  30 
1500  —  20  30 
1800  —  20  36 
2100  —  18  38 
2400  —  18  44 
2700  —  18  49 
3000  —  18  54 
 
5.6 Watertightness of vertical units (4.3.8) 
 
The requirements of EAS 418, 4.3.8 shall not apply to soakaways, nor to vertical units with nominal 
sizes greater than DN 1250. 
 
NOTE EAS 426-200 did not require watertightness tests for chamber and shaft units and for nominal sizes greater than DN 
1250, which often have a low ratio of effective height to nominal size, safety considerations call into question the tests requ ired 
by EAS 418, 4.3.8 . However, such sizes will have thicker walls and so this, together with the requirement for maximum water 
absorption of the concrete, is considered to provide adequate assurance of the durability — see EAS 418, 4.3.8. 
 
5.7 Steps (4.1) 
 
Steps shall be Type D Class I double steps conforming to BS EN 13101:2002 and be manufactured 
from one of the materials specified in 4.2.1 b), excluding flake graphite (grey) cast iron, or 4.2.1 c). 
The minimum length of tread as defined in BS EN 13101:2002, 4.3.2.2 d) shall be 320 mm. 
 
6 Special requirements 
 
NOTE The numbers in brackets after subclause headings are the corresponding subclause numbers in EAS 418. 
 
6.1 Reinforced concrete units and components (5.2) 
 
6.1.1 Concrete cover (5.2.2) 
 
The minimum concrete cover shall be 15 mm (20 mm for slabs, adjusting units and corbel slabs), or 
the relevant nominal maximum size of aggregate stated in the factory documents, whichever is the larger. 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  13 NOTE 1 Given the inspection procedures specified in this part of EAS 426 and the maximum permitted stabilized surface 
crack width specified in EAS 418, 5.2.3 and EAS 418, 5.2.4 the value of minimum concrete cover is consistent with the 
serviceability conditions specified in EAS 418, 4.3.9 . Taken together, these factors are also consistent with the crack control 
provisions given in BS 8110-1 and BS 8110-2. 
 
NOTE 2 Units conveying sea water, industrial waste, etc. and those to be installed in more aggressive serviceability 
conditions than those specified in EAS 418, 4.3.9 might need additional concrete cover. The advice of the manufacturer should 
be sought in such a situation. 
 
6.2 Vertical strength of cover, reducing and landing slabs and corbel slabs (5.2.4) 
 
6.2.1 Vertical strength of slabs to fit cham bers greater than DN 1250 and corbel slabs 
 When subjected to the vertical proof load test for reinforced concrete slabs in accordance with EAS 
418, Annex B with the exception that the loading arr angements shall be as given in Figure 8, Figure 9, 
Figure 10 and Figure 11 of this part of EAS 426 as appropriate, a cover, reducing or landing slab to fit a chamber greater than DN 1250 and corbel slabs shall withstand the relevant vertical proof test 
load(s) given in Table 9. The surface width of any residual crack after removal of the load(s) shall not 
exceed 0.15 mm over a continuous length of 300 mm or more, or the full width of a concrete surface, whichever is the lesser. Where separately required by the relevant sampling procedures, the loading 
shall be taken continuously up to the ultimate (collapse) load without shock and a record made of that 
load. 
 
Table 9 — Vertical proof loads for cover, reducing and landing slabs to fit chambers greater 
than DN 1250 and corbel slabs  
Type of slab  Nominal size of 
chamber unit DN Vertical proof load(s), Fp Loading positions  
1500 (all) 
1800 (all) 
2100 (1200 × 675 access) Two 120 kN loads applied simultaneously 
2100 (675 × 675) 
and (750 × 600 
accesses) See Figure 8 Cover slab 
2400 to 3 000 (all) Three 120 kN loads applied simultaneously 
 
Reducing slab All One 120 kN load and one uniformly distributed 
120 kN load applied simultaneously See Figure 9 
Landing slab All One 35 kN load See Figure 10 
Corbel slab All One 120 kN uniformly distributed load See Figure 11 
 
 
 
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14 © EAC 2006 — All rights reserved  
Dimensions in mm 
 
 
 
Figure 8 — Loading arrangements for cover slabs 
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© EAC 2006 — All rights reserved  15  
Dimensions in mm  
 
 
Figure 8 — Loading arrangements for cover slabs (continued ) 
 
Dimensions in mm 
 
 
Figure 9 — Loading arrangements for reducing slabs 
 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
16 © EAC 2006 — All rights reserved Dimensions in mm  
 
 
Figure 10 — Loading arrangements for landing slabs 
 
 
 
Figure 11 — Loading arrangements for corbel slabs 
 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  17 7 Conformity evaluation 
 
7.1 Application 
 
The conformity evaluation requirements of EAS 418 shall apply to this part of EAS 426 (including 
soakaways, but see 5.6 ), supplemented by the following sampling procedures. 
 
7.2 Finish 
 When subjected to the test given in Annex C the finish of any unit or component (except for the 
external edges of slabs and of adjusting units and corbel slabs) shall conform to 5.3.1 for surface 
voids. 
 
7.3 Geometrical characteristics 
 
Sampling procedures to evaluate the conformity of internal diameter, internal size, thickness and 
straightness to 5.4.6.1 , 5.4.6.2 , 5.4.6.3 and 5.4.6.4 , respectively shall be in accordance with those for 
“Geometrical characteristics — Units” in EAS 418, Table G.1. 
 
7.4 Vertical strength of landing slabs and corbel slabs 
 
Sampling procedures to evaluate the conformity of the vertical strength of landing slabs and corbel 
units to 6.2.1 shall be in accordance with those for “Vertical strength” in EAS 418, Table G.1. 
 
8 Marking 
 
In addition to the requirements in EAS 418, Clause 8 each unit component shall be marked EAS 426-
3 immediately following EAS 418 and with the letter “R” if it is a reinforced concrete unit or 
component. PUBLIC REVIEW DRAFTEAS 426-2:2006  
18 © EAC 2006 — All rights reserved  
Annex A (informative) Information to be supplied in an enquiry or order  
The following particulars cover essential details required by the manufacturer so that an enquiry or 
order may be fully understood: 
 
 Reference in EAS 418 Reference in this 
part of EAS 426 
a) quantity, cross-sectional shape(s) and nominal size(s) of 
units or components  — 5.4.1  
b) design chemical class (DC-class) of concrete in units 4.3.9  5.2.1 
c) if additional concrete cover is required  4.3.9 and 5.2.2  6.1.1 
d) whether double or no steps are to be fixed  4.1, 4.3.3.4 and 4.3.7  — 
e) if the products are to be fully covered by a third party 
certification scheme  7.1  Foreword  
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© EAC 2006 — All rights reserved  19  
Annex B (normative) Standards relevant to EAS 418 
 
The reference specifications prescribed in 5.1 are listed in Table B.1. PUBLIC REVIEW DRAFTEAS 426-2:2006  
20 © EAC 2006 — All rights reserved  
Annex C (normative) Surface void test 
 
C.1 Principle 
 The purpose of this test is to evaluate whether any void in the surface of a unit or component (except 
for the external edges of slabs and of adjusting units and corbel slabs) conforms to the limiting 
requirement in 5.3.1 . 
 
C.2 Apparatus  C.2.1 Gauge , as shown in Figure C.1. 
 
 Dimensions in mm  
 
Figure C.1 ― Gauge for assessing surface voids  
 C.3 Procedure 
 
Apply the ball of the gauge to the void. 
 
C.4 Expression of result 
 
Record whether diametrically opposite points in the rim of the gauge simultaneously touched the 
surface of the unit or component. PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  21  
Annex D (normative) Dimensional tests 
 
NOTE At the manufacturer's discretion it is permissible to use purpose-made “go/no-go” gauges for dimensional 
measurements in lieu of the apparatus specified for the tests in this Annex. 
 
D.1 Internal dimensions test 
 D.1.1 Principle 
 
The purpose of this test is to evaluate whether the internal diameter of circular vertical units and 
tapers, and the width/length of rectangular vertical units, conforms to 5.4.6.1 or 5.4.6.2 as appropriate. 
 
D.1.2 Apparatus 
 D.1.2.1 Steel measuring tape or retractable pocket rule, conforming to BS 4035, with metric graduation 
and figuring conforming to BS 4484-1. 
 
D.1.3 Procedure 
 
For circular vertical units and related tapers, make three measurements of the internal diameter at each end at approximately 60° to each other. For rectangular vertical units, make two measurements 
of each internal dimension at each end. For bas e units, make measurements only at the upper end. 
For all units, take the measurements at approximately 50 mm from the end(s) of the unit. 
 D.1.4 Expression of results 
 
Record whether each measured value of the internal diameter or length/width conforms to 5.4.6.1 or 
5.4.6.2 as appropriate. 
 
D.2 Thickness tests 
 
D.2.1 Principle 
 
The purpose of these tests is to evaluate whether the thickness of a unit or component conforms to 
5.4.6.3 . 
 
D.2.2 Apparatus 
 
D.2.2.1 Outside spring caliper, conforming to BS 3123. 
 
D.2.2.2 Steel measuring tape or retractable pocket rule, conforming to BS 4035, with metric 
graduation and figuring conforming to BS 4484-1. 
 
D.2.3 Procedure 
 
For circular vertical units, use the outside spring caliper to measure the wall thickness at approximately 50 mm from the end of the external barrel at the upper end, at three positions 
equidistant around the circumference of the unit. 
 For rectangular vertical units, use the outside spring caliper to measure the wall thickness at 
approximately 50 mm from the end of the external barrel at the upper end, at each quarter point 
around the perimeter.  
Measure the thickness of tapers using the outside spring caliper at three positions approximately 
equidistant around the upper circumference of the unit and repeat the procedure for the lower 
circumference.  
Measure the thickness of slabs and adjusting units using the steel measuring tape or retractable 
pocket rule at each quarter point around the circumference or perimeter. PUBLIC REVIEW DRAFTEAS 426-2:2006  
22 © EAC 2006 — All rights reserved  
D.2.4 Expression of results 
 Record whether each measured value of the thickness conforms to 5.4.6.3 . 
 
D.3 Straightness test 
 D.3.1 Principle 
 
The purpose of this test is to evaluate whether the internal straightness of a vertical unit having an 
effective height greater than 0.5 m conforms to 5.4.6.4 . 
 
D.3.2 Apparatus 
 D.3.2.1 Rigid straightedge, made into a gauge of the form and dimensions shown in Figure D.1. 
Dimensions in mm 
 
 
 
 
hs = (3.5 h' ± 5 %) in mm 
 
NOTE The studs should be detachable from the basic straight edge to facilitate checking and replacement. 
 
Figure D.1 — Gauge for measuring deviation from straightness 
 
D.3.3 Procedure  D.3.3.1 Place the straightedge within the unit with Edge X (see Figure D.1) in contact with the unit 
and on a line parallel to its vertical axis. Hold the plane of the gauge in a radial plane and make a record of whether or not both ends of the gauge, wherever so placed, were in contact with the internal surface of the unit.  D.3.3.2 If both ends of the gauge were not in contact with the internal surface of the unit at both ends, 
reverse the gauge so that Edge Y, placed as above (see Figure D.1), is adjacent to the internal 
surface of the unit. 
 
D.3.4 Expression of result 
 
Record whether both ends of the gauge were in contact with the surface of the unit when using Edge X, and whether the two studs (see Figure D.1) touched the surface simultaneously when using Edge 
Y. 
 PUBLIC REVIEW DRAFTEAS 426-2:2006  
© EAC 2006 — All rights reserved  23  
Bibliography  
 
EAS 426-200:1994 , Precast concrete pipes, fittings and ancillary products — Part 200: Specification 
for unreinforced and reinforced manholes and soakaways of circular cross-section. 
 
BS 8110-1:1997 , Structural use of concrete — Part 1: Code of practice for design and construction. 
 
BS 8110-2:1985 , Structural use of concrete — Part 2: Code of practice for special circumstances. 
 
BS 8500-1:2002 , Concrete — Complementary British Standard to BS EN 206-1 — Part 1: Method of 
specifying and guidance for the supplier.  BS 8500-2:2002 , Concrete — Complementary British Standard to BS EN 206-1 — Part 2: 
Specification for constituent materials and concrete.  BS EN 752-2:1997 , Drain and sewer systems outside buildings — Part 2: Performance requirements. 
 
BS EN 752-3:1997 , Drain and sewer systems outside buildings — Part 3: Planning. 
 BS EN 752-4:1998 , Drain and sewer systems outside buildings — Part 4: Hydraulic design and 
environmental considerations. 
 
BS EN 1295-1:1998 , Structural design of buried pipelines under various conditions of loading — Part 
1: General requirements. 
 
BS EN 1610:1998 , Construction and testing of drains and sewers. 
 
 
   
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