Publishing and copyright information

The BSI copyright notice displayed in this document indicates when the document was last issued.

© BSI 2008

ISBN 978 0 580 64038 4

The following BSI references relate to the work on this standard:

Committee reference B/505
Draft for comment 07/30138205/DC

Publication history

First published April 1983
Second edition, December 2007

Foreword

Publishing information

This British Standard was published by BSI and came into effect on 31 December 2007. It was prepared by Technical Committee B/505, Wastewater engineering. A list of organizations represented on this committee can be obtained on request to its secretary.

Supersession

This British Standard supersedes BS 6297:2007, which is withdrawn.

Relationship with other publications

This code of practice encompasses some of the subject matter previously covered by BS 6297:1983 in relation to drainage fields. It is complementary to BS EN 12566, which covers small treatment systems up to 50 population equivalents and BS EN 12255, which covers the design of larger treatment systems.

Much of the text is based on CEN/TR 12566-2:2005¹⁾ [1], so many of its provisions now have the force of this full national British Standard. BS 6297 would be further amended if the current prCEN/TR 12566-5, dealing with pre-treated effluent filtration systems, is published by CEN.

Information about this document

This is a full revision of the standard, and introduces the following principal changes.

It provides advice on the treatment and dispersal of partially treated wastewater effluent so as to minimize environmental, amenity or public health problems which could arise from the inappropriate use of non-mains wastewater systems.

It covers applications from single households to small communities, including holiday parks with up to 250 population equivalents (PE).

It gives guidance for those designing and installing drainage fields and infiltration systems for use in wastewater treatment. It includes designs of the most commonly used drainage fields. However, alternative infiltration systems are acceptable for specific locations and specialist advice can be sought where appropriate. It is not intended for the code of practice to inhibit the development and application of suitable new processes, and where alternative options for disposal are being considered, the environmental regulator can be consulted to ensure suitability.

The long-term performance of these systems will be dependent on appropriate use and the level of maintenance carried out on upstream treatment equipment.

Use of this document

As a code of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading.

Any user claiming compliance with this British Standard is expected to be able to justify any course of action that deviates from its recommendations.

Presentational conventions

The provisions in this standard are presented in roman (i.e. upright) type. Its recommendations are expressed in sentences in which the principal auxiliary verb is “should”.

Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.

Contractual and legal considerations

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

1 Scope

This code of practice gives recommendations and guidance on the design and installation of drainage fields and infiltration systems for use in wastewater treatment. It is applicable to systems for handling discharges from domestic and commercial sources from single households upwards. These sources are typically septic tanks and package treatment plants.

General guidance is given on good design and installation practices. Particular requirements are determined by local conditions. The recommendations are supplemented, as required, by specialist advice.

NOTE Attention is drawn to the environmental regulators Pollution Prevention Guidelines Note 4 [2] and building regulations and standards (see Annex B). These require an adequate system of drainage to carry foul water from appliances within the building to one of the following, listed in order of priority:

public sewer
a private sewer communicating with a public sewer
either a package wastewater treatment plant or septic tank, with a discharge to a properly designed drainage field.

Only where it can be demonstrated that the cost and/or practicability of connection to the public foul sewer is not feasible will alternative options, including use of drainage fields, be considered acceptable.

2 Normative references

3 Terms and definitions

4 Drainage fields

5 Preliminary planning, site investigation and assessment

5.1 General

5.2 Preliminary planning

5.3 Site investigation

5.4 Assessment

6 Detailed system design

6.1 Estimating drainage field area

6.2 Percolation test procedure

6.3 Calculating trench area and trench length

6.4 Trench depth

6.5 Effluent distribution

6.6 Drainage field layout

6.7 Other design parameters

6.8 Dealing with difficult sites and ground conditions

7 Components

7.1 General

7.2 Distribution pipe

7.3 Infiltration pipe

7.4 Granular fill material

7.5 Geotextile membrane

7.6 Effluent pumping systems

7.7 Chambers

8 Construction of drainage field

8.1 Inspection and distribution chambers

8.2 Infiltration trenches

8.3 Installation of infiltration pipes

9 Maintenance

9.1 General

9.2 Regular checks

Bibliography

BS 6297:2007+A1:2008

Code of practice for the design and installation of drainage fields for use in wastewater treatment

Current

Published:

31 Dec 2007