Most structural and hydraulic calculations for the design of drainage and sewerage systems using vitrified clay pipes can be simply carried out using the tables provided in the booklet .The additional tables in the bedding construction section of this booklet provide an alternative approach to the presentation of design information, as detailed in the following paragraphs. The additional flow capacity tables use pipe roughness values that only apply in special cases, such as for chemical drainage.

The bedding construction section of this booklet will help engineers who decide not to apply individual structural design from first principles to each sewer. The fill load tables have been calculated  using Marston theory, and the surcharge load tables have been calculated by the Boussinesq  Equation.

The load tables are in two sections. The first comprises 20 tables of design loads and the required minimum bedding load factors for the combination of fill loads and loads due to two types of traffic wheel loads on 100 mm to 600 mm diameter vitrified clay pipes. The second consists of two tables of fill loads, and  two tables of loads acting upon the pipeline due to traffic wheel loads acting on the surface of the fill.

The flow tables in this booklet will assist the designer of foul and  surface water drainage schemes to size pipelines hydraulically by the use of the uniform  flow equation derived by Colebrook and White. The information is in tabular form and the  range of 100 to 1000 mm diameter pipes is covered.

There are eight tables in the flow section of the booklet. The first two are for use in the design of chemical drainage  for pipes flowing full with k_s values of 0.03 mm and 0.06 mm. The third table  is for use in the design of foul or combined systems and is for pipes flowing at a  proportional depth of 0.75. The k_s value of 0.3 mm is applicable to velocities  above 1.5 m/sec, the k_s value of 0.6 mm is applicable to velocities greater  than 1.0 m/sec and less than or equal to 1.5 m/sec and a k_s value of 1.5 mm is  used for lower velocities. The fourth table is also for foul or combined systems using the  same k_s values, but for pipes flowing full. The fifth, sixth and seventh tables  are for the design of surface water systems flowing full with k_s values of 0.3,  0.6 and 1.5 mm. The last table gives proportional velocities and discharges in pipes  running part full.

In editing this 2nd Edition of Dr. Pomeroy's  well known booklet, Arthur Boon, himself an acknowledged authority on the subject in the UK, has incorporated the results of research carried out since its first publication and brought in some additional detail.
The booklet describes the formation and effects of hydrogen sulphide in sewers. The hydrogen sulphide is oxidised by micro-organisms on walls of sewers to sulphuric acid which can cause corrosion of cement-bonded materials.

It sets out the strategies which may be adopted to obviate the problem. Predictive equations are given so that analysis may be made of conditions where the hydrogen sulphide can occur.

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This booklet covers the way in which pipe material selection, planning, design and construction issues for drains and sewers are dealt with and brings together into one booklet the relevant information on these subjects previously published by the Association in separate documents.

The publication of the European standard BS EN 295 for vitrified clay pipes for drains and sewers in 1991 and subsequent amendments introduced a new dimension into the specification of clay pipes and its use is covered.

The publication during 1997 and 1998 of new European standards covering the design and construction of drains and sewers has meant that they have superseded BS 8301 for Building Drainage and BS 8005 for Sewerage. These new standards are BS EN 752 - Drain and sewer systems outside buildings, BS EN 1295-1 - Structural design of buried pipelines under various conditions of loading and BS EN 1610 - Construction and testing of drains and sewers.

References are given throughout the text to the relevant standard and clause number.  Hydraulic and structural design is covered and a range of easy-to-use design tables provided in two appendices.  A simplified bedding construction table is also included, covering pipe sizes up to 600 mm diameter and showing the depth ranges over which clay pipes can be laid on a full range of beddings.

Construction is fully covered with trench excavation, pipe laying, trench backfilling and inspection and testing all detailed. A full description of the procedures for water and air tests is given together with acceptance criteria and possible reasons for failure.  An illustrated section covers the whole process of laying vitrified clay drainage systems in an easy-to-follow sequence.  Aspects from delivery right through to testing the laid pipeline are shown and a brief description of each activity is included.

This booklet is not designed to replace the advice given in the standards themselves, to which reference should be made for detailed guidance.

Methods used to deal with particular situations that often arise when laying pipes, but are seldom fully covered in Codes of Practice or other technical literature are described.  These deal with the means of laying pipes in soft ground, waterlogged conditions, through and under structures, with concrete beddings, at shallow depths, the use of repair and adaptor couplings and the ability of clay pipes and fittings to resist chemicals in effluents and contaminated ground.    

A cost comparison report is included, based on two small developments typical of the late 90's, five terraced houses and five detached houses.   It shows that using clay pipe drainage systems is much more cost-effective than using alternative pvc-u systems, for which very large discounts have to be obtained to make their use viable.

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