080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

Lee Tunnel, Contract No. 6LYG/A1
PT – Particular Tunnelling Specification - PT300
PT322.3
PT322.4
PT322.5
PT322.6
PT322.7
PT322.8
a) The Contractor shall design, provide, operate and maintain for duration of
tunnelling construction a temporary ventilation system, which conforms to
the Health and Safety requirements. The equipment shall be adequate to
maintain sufficient supply of fresh air in underground work areas.
b) The design of the ventilation system shall take into account any mitigation
measures the Contractor may deem necessary having regard to the
potential for the migration of any gases and contaminated material into the
tunnel or shafts from the contaminated materials as detailed in the Reports
and Site Information at Abbey Mills to be found in Schedule 6 of the Works
Information
i) Mechanical ventilation systems shall not be removed without the
approval of the Project Manager.
ii) As a minimum, in good air quality, when the excavations are occupied
by workers, the ventilation system shall be designed to deliver fresh air
at a volumetric flow rate equal to 20mtrs per minute times the crosssectional
area of the tunnel. A higher volumetric flow rate shall be
provided if necessary
iii) Power to the main ventilation system shall not be interrupted in the
event of an alarm of the air monitoring system.
iv) Advance of the ventilation system shall be made a regular part of the
normal tunnel excavation cycle.
Temporary Tunnel Lighting System
The Contractor shall provide a temporary lighting system in the tunnel which
conforms to the requirements of BS6164:2001“Code of practice for safety in
tunnelling in the construction industry”. Lighting in the tunnel shall extend the full
length of the tunnel and not be less than that required for safe working and
access. An alternative source of power and emergency lighting system shall be
provided to allow emergency securing operations and safe evacuation in the
event of a primary power failure. An adequate number of hand lamps shall be
located at key points underground.
Temporary Personnel Walkway
The Contractor shall provide walking access in the tunnel at all times. This shall
have a firm, level, slip-resistant and continuous surface and shall be suitable for
use in emergencies.
Hop ups for pedestrian safety shall be provided in the tunnel at a minimum of
100mtr centres.
Temporary Locomotive Track
The track should be properly supported and secured against displacement in the
tunnel. The entire length of the track shall be examined not less than once a
week and the results of this inspection shall be forwarded to the Engineer.
Defects shall be recorded and remedial action will be promptly implemented
when identified.
Temporary Pumping
Provide intermediate pumping stations and reserve pumping capacity at the any
point of the tunnel as required to remove groundwater inflows and construction
water.
Fire Extinguishers
Fire extinguishers shall be provided at a minimum every 500 metres of the
running tunnels. They shall be maintained in accordance with the manufacturer’s
recommendations.
Thames Water Utilities Limited August 2008
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