Model Consultative Procedure for
Pipeline Construction involving Deep Excavation
ERS M60
January 1993
FOREWORD
- This document sets out a procedure to
provide a consistent approach
to avoiding problems with the underground pipeline assets of the water,
sewerage
and gas undertakers when trenching works are carried out.
- Trenching
activities were highlighted by the
King Inquiry1 in 1977 as
one source of ground movement responsible for the fracture of grey iron
gas
pipes. This was confirmed by subsequent studies of fracture records and
extensive research culminating in a damage control agreement between
British
Gas and the National Water Council in 1982, and effective from 1st
January 1983.
The procedure and its revisions were formally applied until November
1990.
This
document represents a major revision of the old procedure based on more
recent
data and improved analysis techniques.
The new procedure differs from
the old procedure
in the following
- It allows all
pipe sizes to be
assessed
- It
provides a more comprehensive range of ground
classifications
- It
differentiates between trafficked and untrafficked
situations
- It allows for some pipes crossing trenches to be
protected
by
excavation
- The document
relates to consultation between water or sewerage
undertakers or their agents and the appropriate region of British Gas
whenever
trenching works are proposed by either party. Emergency works are
excluded.
- The
procedure is intended to be reciprocal between the
undertakers.
- This damage control procedure
deals with the notification, design and execution of trenching works so
as to
minimise the risk of damage to grey iron mains and reduce the cost and
inconvenience
to all concerned.
Deep excavation in the vicinity of asbestos cement
and
clayware pipes is outside the scope of the procedure. In the event or
such
excavation, special arrangements shall be negotiated locally within the
spirit
of the agreement.
- The procedure is intended to supplement but
not to amend, abridge or
override any provisions in respect of street works under Acts of
Parliament,
and to operate within the framework of statute and common law governing
the activities
of both industries.
The document also supplements the British Gas
Engineering Standard
PS/G10
- Regular consultation and the application of
the acceptable proximity
criteria should allow problems to be identified and resolved at an
early stage,
to achieve a least cost solution.
- Should difficulties arise the matter should
be resolved whenever
possible by local agreement.
- The technical content of this document has
been formulated by the
British Gas Engineering Research Station and appraised by the Water
Research
Centre. Situations outside the scope of this document do not
necessarily represent
acceptable conditions.
1 King, P. J., Clegg, G. T. and Walters, W. J. Report of the Inquiry into serious gas explosions. Department of Energy, HMSO. June 1977.
Copies of this report are available from the Foundation, price
£30.00 less 20% for FWR members