mscc water level control - operational protocol final 25 -1-11€¦ · the sluice control system is...

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Peel Holdings January 2011

Manchester Ship Canal Company Water Level Control - Operational Protocol Private and Confidential

Prepared by: ............................................................. Checked by: ........................................................................ David Stork Roy Lobley Associate Director Associate Director Approved by: David Stork Associate Director

Manchester Ship Canal Company Water Level Control - Operational Protocol 3rd Floor, 8 Princes Parade, Princes Dock, Liverpool, L3 1QH Telephone: 0151 331 8900 Website: http://www.aecom.com Job No 60144094 Reference 60144094/REPORT/001 Date Created January 2011 This document is confidential and the copyright of AECOM Limited. Any unauthorised reproduction or usage by any person other than the addressee is strictly prohibited.

1 Introduction ....................................................................................................................................................................... 2

2 Overview of the Manchester Ship Canal Water Level Control Structures .................................................................... 4

2.1 The Water Level Control Structures from West to East ......................................................................................... 4

3 Detailed Description of the Water Level Control Structures ....................................................................................... 10

3.1 Overall Description of the Sluices ........................................................................................................................ 10

3.2 Upper Reaches Sluices ....................................................................................................................................... 10

3.3 Weaver Sluices .................................................................................................................................................... 10

3.4 Gate Description .................................................................................................................................................. 10

3.5 Operating Machinery ........................................................................................................................................... 11

3.6 Control System .................................................................................................................................................... 12

3.7 Control System Communications......................................................................................................................... 13

3.8 Other Water Level Control Structures .................................................................................................................. 13

4 Description of Normal Water Level Control .................................................................................................................. 16

4.1 Water Level ......................................................................................................................................................... 16

4.2 Sluice Gate Control .............................................................................................................................................. 16

4.3 Effect of Tidal Conditions ..................................................................................................................................... 17

5 Description of Operational Control During High Water Flows .................................................................................... 19

5.1 Monitoring for High Water Flows ......................................................................................................................... 19

5.2 Environment Agency Flood Warning Procedure .................................................................................................. 19

5.3 Procedure in the Event of Anticipated High Water Flows .................................................................................... 20

5.4 Resources available ............................................................................................................................................ 21

5.5 Communication .................................................................................................................................................... 21

5.6 Training ................................................................................................................................................................ 21

5.7 Testing of Backup Procedures ............................................................................................................................. 21

6 Routine Maintenance and Major Maintenance/Capital Renewal Programme ............................................................ 23

6.1 Routine Maintenance ........................................................................................................................................... 23

6.2 Major Maintenance .............................................................................................................................................. 24

6.3 Capital Renewal Programme ............................................................................................................................... 24

7 Reliability of Sluice Operation ....................................................................................................................................... 26

7.1 Reliability Analysis ............................................................................................................................................... 26

7.2 Blockage of sluices and weirs by debris .............................................................................................................. 27

8 Working Arrangements ................................................................................................................................................... 29

Table of Contents

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1 Introduction

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The purpose of this document is to provide a robust operational protocol which recognises the close working relationship

between the Environment Agency and the Manchester Ship Canal Company (MSCC) as it affects the control of water levels in

the Manchester Ship Canal (MSC). The MSCC is part of Peel Ports (Peel).

It is the responsibility of the MSCC, to control the water levels in the Canal. The following is a brief description of the powers

under which the Canal operates.

The Manchester Ship Canal was authorised in 1885 under the Manchester Ship Canal Act 1885 (the 1885 Act). This gave MSCC

various powers to build, manage and operate the Canal. Once constructed, the Canal facilitated navigation from the River

Mersey to Manchester. Subsequent Private Acts of Parliament were promoted to authorise new construction along the Canal and

to regulate its operation. However, the main provisions relevant to the upper part of the Canal are set out in the 1885 Act. The

1885 Act provided, amongst other things, for the Company to be granted powers to work weirs, sluices, machinery, appliances

and apparatus.

Section 17 of the Regulation of Railways Act 1873 applies to the Company. This provision requires “every railway company

owning or having the management of a canal to keep it at all times such canal and the works belonging thereto thoroughly

repaired and dredged and in good working condition so that it may be at all times open to navigation for the use of all persons

desirous to use and navigate the same”. The Company remains bound by this requirement as a statutory railway company.

The Company is therefore required to ensure the Canal is at all times properly maintained. The controlling of the water level is

part of this responsibility.

Since the MSC was opened there have been many changes in the surrounding environment, especially the growth of

Manchester, changes in weather patterns and changes in our understanding of flooding and its causes. The MSCC has

successfully controlled the water levels since its opening but it is recognised that there is a need for a wider understanding of this

process and how this successful record will be maintained.

The sluice control system is used to control the canals water level for navigation purposes and in doing so it is also effective in

preventing flooding in the locations surrounding the Canal.

Sections 1 to 7 of this document describe the sluices, the risk of failure in a quantifiable form, the maintenance and refurbishment

regime in place and MSCC procedures that need to be in place. Section 8 discusses the cooperation that is in place between the

Environment Agency and Peel. MSCC is a Professional Partner of the Environment Agency.

This will enable all stakeholders to have confidence in and recognise the effectiveness and reliability of the water level control

system in providing a flood risk management capability. It will inform flood defence strategies for the land bordering on the Canal.

1 Introduction

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2 Overview of the Manchester Ship Canal Water Level Control

Structures

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2 Overview of the Manchester Ship Canal Water Level Control

Structures

2.1 The Water Level Control Structures from West to East

The Ship Canal was constructed by canalising the Rivers Irwell and Mersey above Latchford (the Upper Reaches) and by

constructing a new water course between Latchford and Eastham (the Lower Reaches). See figure 9 for a schematic of the

canal and the location of the various structures.

In addition to the Rivers Irwell and Mersey, main rivers such as the Salteye Brook, Sinderland Brook and River Bollin run into

the Canal in the Upper Reaches and the River Weaver in the Lower Reaches. A large number of outfalls, including storm

water outfalls, also discharge into the Canal.

In the Lower Reaches the Canal also receives water from two other sources:

• When High Water at the Weaver sluices is above the top of the gate, the River Mersey will overtop the sluice

structure into the Canal. In these circumstances there will also be overtopping of the lock gates at Eastham;

• A set of what are referred to as ‘storm gates’ are fitted at Eastham Locks. They are designed so that when closed

they prevent the River Mersey flowing into the Canal when it is at a higher level than the Canal during Spring

High Waters. Under normal operations these gates are closed when the river is predicted to reach a higher level

than the Canal. If they are not closed for any reason the River Mersey will flow into the Canal resulting in an

increase in the water level to that of the river at Eastham, with a hydraulic gradient upstream of Eastham. The

gates are occasionally kept open for operational reasons. They are kept closed if a storm surge is predicted.

The water level in the Canal is controlled by five sets of sluices and two weirs. On the Upper Reaches they consist of:

• Mode Wheel Locks - 4No sluices control the water level in the

Mode Wheel Pond upstream of Mode Wheel Locks– See

Figure 1;

• Barton Locks – 4No sluices control the water level in the

Barton Pond, between Barton Locks and Mode Wheel Locks.

In addition there is a hydro-generation plant located at Barton

which can contribute to the available capacity. This is located

in a building just downstream and separate to the sluices. It is

fed from the sluice way through the 45ft lock wall - See

Figure 2;

Fig 1

Fig 2

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• Irlam Locks – 5No sluices control the water level in the Irlam

Pond, between Irlam Locks and Barton Locks – Figure 3;

• Latchford Locks – 3No sluices control the water level in the

Latchford Pond, between Latchford Locks and Irlam Locks –

See Figure 4;

• Woolston Weir - This weir contributes to the control of

the water level in the Latchford Pond – See Figure 5;

Fig 3

Fig 4

Fig 5

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• Woolston Guard Weir. This weir is used to enable

maintenance to be carried out on the Woolston and

Howley weirs. It consists of 16 radial gates which are

kept open in normal conditions. If maintenance is

required on the weirs the gates are closed which

reduces the flow of the River Mersey over Woolston

and Howley Weir. This lowers the river level between

the two weirs allowing maintenance work to be carried

out. The gates would not be closed during periods of

heavy sluicing - see Figure 6;

• Howley Weir. This weir, although downstream of Woolston Weir can

have an effect on the volumes Woolston Weir can handle in extreme

tidal events. When this weir is overtopped the downstream water

level at Woolston Weir is raised, so reducing the flow through the

weir - see Figure 7;

The sluices at Mode Wheel, Barton, Irlam and Latchford control the water level by enabling the waters coming into the Canal

from the Rivers Irwell, Mersey, and others detailed above, to be passed down the Canal in a controlled manner. In all but the

most extreme low rainfall conditions there will be sluices operating on a regular basis at all locations apart from Latchford

where they do not operate until flows down the River Mersey exceed 140cumecs.

The water level in the lower reaches is controlled by the following:

• Weaver Sluices – 8No sluices control the water level in the Eastham pond (Lower Reaches) between Latchford

Locks and Eastham Locks – See Figure 8.

These sluices control the water level by enabling the waters coming into the Canal from the Rivers Weaver and from the

Upper Reaches via Latchford Locks and sluices to be passed down the Canal in a controlled manner. Note that although there

are 10 sluice positions only eight are fitted with machinery with which to operate the gates.

Fig 6

Fig 7

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A comprehensive study of the Canal and its operation in various flow conditions is provided in a Hydraulic Modelling Study

carried out, and maintained for the Company, by consulting engineers Halcrow Group Ltd. The study explains how the various

structures affect the canals hydrology during both fluvial and tidal events.

Section 4 & 5 of this Protocol includes a description of the sluice control system.

Comprehensive drawings of the sluice machinery are held by the MSCC.

Figure 9 shows the arrangement schematically.

Fig 8

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Schematic of Manchester Ship Canal showing assets that contribute to managing flood risk

Manchester Ship Canal (MSC)

X Lock

Sluice Gate

H Hydro Generation Unit

< Direction of flow

Weir/Sluice System

Major Main River

Mode Wheel Locks 1 2 3 4

Major Non-main River

Tidal River

X Lock

Barton Locks H 1 2 3 4

Irlam Locks 1 2 3 4 5

Mersey Weir

Woolston Guard weir

Latchford Locks 1 2 3

Woolston Weir

Howley Weir & Sluice

Weaver Sluice

1 2 3 4 5 6 7 8 9 10

Note that 1 & 10 are not in use

Eastham Locks

< River Weaver

< Red Brook

< Ketwick Brook

River Glaze >

< M

SC

(La

tch

ford

Po

nd

)

XX

< River Bollin

Salteye Brook >

X X

< M

SC

(Irl

am

Po

nd

)

< River Mersey

<Laskey Brook

X

< R

ive

r M

ers

ey

E

stu

ary

(T

IDA

L)

< M

SC

(Fa

sth

am

Po

nd

)

X X

X X X

< M

SC

Mo

se

Wh

ee

l P

on

d

< R

ive

r Ir

we

ll

Flows out

of the

canal

influenced

by the

height of

tide in the

River

Mersey

Key

< M

SC

(Ba

rto

n P

on

d)

< River Mersey

< R

ive

r M

ers

ey

(T

IDA

L)

X

Fig 9 Schematic of Manchester Ship Canal

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3 Water Level Control Structures

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Capabilities on project:

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3.1 Overall Description of the Sluices

The sluices at Mode Wheel, Barton, Irlam, Latchford and Weaver consist of vertical steel counterbalanced roller gates operated

by machinery located on a gantry above the sluices. The gantry sits on masonry piers which transfer all loading onto a masonry

base.

The general arrangement of the sluices is generally similar at all locations. There are some differences in the height of the gates

but apart from that the gates are similar. A programme of replacement of the sluice gates means that there are two forms of

construction, but overall dimensions of the sluices remain the same. These are described in section 3.4.

Stop logs are provided to enable each sluice to be isolated from the canal/river for maintenance purposes. The stop logs are of

steel construction with either timber and felt seals or timber and composite rubber seals.

3.2 Upper Reaches Sluices

The sluices are all of similar overall construction, with a variation in the number at each site and small variations in heights. A

masonry ‘boom’ is located on the upstream side to protect the sluices from errant vessels.

A diesel-hydraulic semi-goliath gantry crane is located on the upstream side of the sluices, one rail set onto the boom and the

other running across the piers at top gantry level. This crane is used to install and remove the upstream stop logs. The stop logs

are installed using a beam that is hooked onto the stop logs lifting lugs with a remote release mechanism. This enables the stop

logs to be installed in the event of a gate jamming in the raised position, when divers would not be able to enter the water. The

stop logs can be removed by the same beam, again without divers needing to enter the water.

The downstream stop logs can be installed by a floating crane such as MSCC’s CB Buffalo, or in some locations a land based all

terrain mobile crane.

3.3 Weaver Sluices

The Weaver Sluices are located between the Canal and the River Mersey, opposite the River Weaver. They are accessed by

boat.

A floating crane is used to install the canal-side stop logs. A diesel-hydraulic semi-goliath crane is situated on the river side of the

sluices. This is used to install the riverside stop logs.

A walkway is located on the river side of the sluice to gain access from one end of the structure to the other. A landing stage is

provided at the upstream and downstream end of the structure for berthing vessels. This allows access to the sluices even at

times of heavy sluicing.

3.4 Gate Description

There are two types of gate construction.

a) Ransom & Rapier Gates - see Figure 10

This type of gate is fitted to the sluices at Mode Wheel (4No), Barton (3No), Irlam

(4No), Latchford (3No) and Weaver (5No). These gates are of riveted and bolted

steel construction. The upstream side of the gate is flat and the downstream side

has a lattice-work beam arrangement. The gates are guided by cast steel wheels

with phosphor bronze bearings which run on steel tracks set into the masonry. On

the upper reaches gates there are seven pairs of wheels, and on the Weaver gate

there are five pairs. Steel staunching rods hang from the upstream side of the gate

in the upper reaches and on both sides of the gates at Weaver to provide a sealing

3 Detailed Description of the Water Level Control Structures

Fig 10

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arrangement. The sill seal comprises a timber seal on the gate sealing against a timber seal set into the masonry. The residual

life of the gates is estimated to be between 5 and 10 years with the current maintenance regime in place. This period could be

extended by undertaking some major refurbishment work.

b) Halcrow Gate – See Figure 11

These gates are fitted at Barton (1No), Irlam (1No) and Weaver (3No) and are of an all welded construction. The

upstream side of the gate is flat and the downstream side has a fabricated beam arrangement. The gates are guided by

cast steel wheels with Orkot bearings (resin impregnated marine bearing material) which run on steel tracks set into the

masonry. On the upper reaches gates there are seven pairs of wheels, and on the Weaver gate there are five pairs. Steel

staunching rods hang from the upstream side of the gate in the upper reaches and on both sides of the gates at Weaver

to provide a sealing arrangement. All the wheels have an automatic lubrication system for the bearings. The residual life

of these gates between refurbishment is estimated at a minimum of 20 years.

Fig 11

3.5 Operating Machinery

The sluices are operated by an electric motor driven gearbox, see Fig 12.

Fig 12

The gearbox drives two drive shafts that are connected to side gearboxes which drive leaf chains. The side gearboxes have

sprockets driven from the main gearbox over which leaf chains sit. The sprockets drive the leaf chains which are connected

between the gate and counterbalance.

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Limit switches are fitted to the main gearbox which stops the sluice gates at the limit of their travel in both directions to prevent

the gate clashing with the top gantry whilst being raised and the counterbalance similarly clashing whilst the gate is being

lowered.

The sluices are electrically powered and normally operate in automatic control mode. Each location has two independent power

supplies with an automatic change over if one should fail. If this should occur this is notified to the Port Operations Controller

(POC) as a fault condition via the Supervisory Control and Data Acquisition (SCADA) system which allows the maintenance team

to be alerted, see Section 3.6. This function is checked during routine maintenance visits.

There are three levels of backup for the operation of the sluices:

• Main electrical power supply in manual control mode

Each sluice can be operated from a local control station located on the platform on which the operating machinery is

installed. This facility is used during routine maintenance whilst checking the operation of the sluices. To enable the

local control requires a key switch to be operated in the main control panel. This change in status is monitored by

the SCADA system and will be notified as an event to the POC.

• Hydraulic drive

If there is a power failure to the sluices each sluice can be individually operated by a hydraulic drive that is powered

by the semi-goliath gantry crane petrol engine driven hydraulic power pack. The drive is through the main gearbox

using the manual drive connection. This device fits on the hand winding drive shaft. A limit switch is fitted to this

shaft and if the device is fitted the electrical operation of the sluice is disabled and an alarm is raised by the SCADA

system and will be notified as an alarm to the POC. It takes 27 turns of the handle to move the gate 100mm.

• Manual operation

A further backup if the hydraulic drive fails is that each sluice can be manually operated through the main gearbox to

which a hand lever can be fitted. The winding handle is slid onto the hand winding drive shaft. A limit switch is fitted

to this shaft and if the handle is fitted the electrical operation of the sluice is immediately disabled and an alarm is

raised by the SCADA system and will be notified as an alarm to the POC.

Operators are required to put into place the backup arrangements, see Section 5.

3.6 Control System

The sluices were originally manually operated Stony Sluices. These sluices were replaced in the 1950’s with sluices

manufactured by Ransom and Rapier which are electrically operated.

In 1989 the Mode Wheel sluices were automated by installing PLC’s (Programmable Logic Controllers). Barton and Irlam were

automated in 1991 and Latchford in 1992. At this time a ‘Linklaser’ SCADA system was installed. Weaver was automated in 2000

and added to the SCADA system.

The sluices have a local power supply and are normally controlled locally by the PLC. The control equipment is located in a

control room situated by the sluice structure. Access to this control room is via a high security lock with the key held by

authorised persons. Similarly access to the top gantry where the machinery is located is by authorised persons only.

A CCTV system is installed that enables the POC to monitor the activities at the sluices.

The SCADA system provides a central monitoring and limited control capability which allows the operators to monitor the water

levels remotely, monitor the performance of the sluices themselves and provides some limited control capability. The SCADA

system continuously monitors the status of all the sluices, whether they are in auto, local or off, their position and water levels.

The availability of the sluice is also inputted into the SCADA system by the POC so that if a sluice is under maintenance this is

recorded in the system. The POC cannot turn the sluices off, this being undertaken locally from the Sluice Control Room building.

The control system is currently being updated with new PLC’s being installed along with a new SCADA System. This provides a

similar level of supervision and control for the POC based at Eastham as the Linklaser system it replaces. A more detailed

explanation of how the sluices are controlled is provided in Section 4.

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Data is collected by the SCADA system monitoring the status of the system and reporting faults. These include:

• Gate positions;

• Water levels;

• Gate availability;

• Power supply in use;

• Position discrepancy. This is monitored by checking between the gate and counterbalance. If the difference

between the two strays outside a predefined setting a position discrepancy signal is generated and the gate will not

be asked to move again;

• Switchgear faults;

• Motor overload – caused by a motor fault of sluice jamming;

• Triple validation of the water level sensors;

• Loss of communication with the SCADA system, and;

• Hand gear sensed to be in place.

All faults are automatically sent to the POC via the SCADA system.

A detailed explanation on the above can be found in the Operation and Maintenance (O&M) manual for the sluices SCADA

System.

Those with the appropriate authority can intervene in the automatic sluice control using the SCADA system as follows:

• At Weaver Sluices the gates can be lowered to allow a vessel to safely pass without affecting the navigation of the

Canal. When this hold is removed the sluices automatically return to the required position. This is a routine

procedure and is the responsibility of the POC;

• All gates can be held at their current position. This requires the Harbour Masters permission;

• The water level in each pond can be adjusted within predefined limits by modifying the set point of the control

system. This requires the Harbour Masters permission.

3.7 Control System Communications

The PLC's are stand alone and do not communicate with each other. There is communication with the iFix SCADA system via a

Wide Area Network connection. This provides inbuilt redundancy as it makes use of British Telecom’s communication network, IP

Clear. This is fully monitored by British Telecoms Global Services who monitor the BT circuits raising alarms when circuits are

not responding so any faults are reported and attended to as they occur.

3.8 Other Water Level Control Structures

In addition to the sluices the following structures contribute to the control of the water levels

a) Woolston Siphon Weir

This structure, along with the sluices at Latchford, maintains the water level in the Latchford Pond. It is located on the

River Mersey and all the water flowing into the River Mersey passes over the weir. It was constructed in 1994 and

replaces a weir built in the 1890’s.

It consists of two ogee weirs and nine air regulated siphon weirs. This automates the process of maintaining the water

levels upstream of the weir.

Flows of up to 140cumecs can flow over the weir before Latchford Sluices are required to operate. Once the flow through

the Latchford sluices reaches capacity additional flow will then pass through Woolston Weir. The performance of the weir

is dependent on the downstream levels and this is controlled by Howley Weir.

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b) Howley Weir

Howley Weir is the normal tidal limit for the River Mersey. It maintains water levels downstream of Woolston Weir.

Extreme tides can overtop Howley and raise the water level in the river downstream of Woolston Weir. This will reduce the

efficiency of the siphons until the tide recedes and restore the normal water level.

c) Woolston Guard Weir

This structure is provided to enable the maintenance of Woolston and Howley Weirs. It has 16 radial gates which when

closed reduces flow down the Mersey to enable essential maintenance work to be safely undertaken. This would only be

carried out only during periods of low flow. Normally the gates are kept open. The guard weir also reduces the flow of

debris into the siphon weirs reducing the blockages in the structure. There is a regular maintenance regime in place to

clear the guard weir and siphon weir of debris.

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4 Description of Normal Water Level Control

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4.1 Water Level

Under normal flow conditions in the Canal the sluices automatic control system is designed to control the water levels within the

Canal to enable safe navigation of vessels using the Port. In achieving this, water levels are maintained so that the risk of

flooding is also minimised.

This automatic control system replaced the local control of the sluices by a team of operators permanently located at each lock

and at Weaver Sluices. The local control system was retained at each of the sluices. It is used for the maintenance of the sluices

and as a backup system.

The water level in each pond is controlled locally and independently, i.e. no water level or sluice gate positions from the sluice

upstream are used to determine gate opening. The water level control is achieved by the control system continuously monitoring

the water level and comparing this to a level set in the PLC software, the set point. The sluice gate opening is adjusted, either

being raised if the measured water level is above the set point, or lowered if the water level is below the set point.

The set point can be adjusted remotely by the POC at Eastham within certain limits. Altering the set point can only be done with

the authority of the Harbour Master.

The water levels are monitored by ultrasonic sensors. Mode Wheel, Barton and Irlam have 3No transducers each, thus providing

a system of triple validation. Provided at least one is operating the control system will operate. If all level sensors fail the gates

will freeze in their last position until the fault is rectified. As soon as one sensor fails or there is a discrepancy between any two

sensors an alarm is raised on the SCADA system

Latchford has two sets of transducers one local at Latchford and one at Rixton Junction where the River Mersey leaves the

Canal. This communicates with the Latchford PLC via a BT private wire. The Rixton water level is the default measurement used

to control the sluices but if these should fail then the Latchford water level is used and the control system makes allowances for

this.

Weaver has two sets of transducers, three on the river side and three on the canal side.

The water levels are captured and monitored by the SCADA system and an alarm is raised if the water level rises above an

alarm point. The POC also visually monitors the water levels via the VDU screens in the control room and also by the images

from the CCTV cameras at each sluice location. The experience of the POC operatives enables them to recognise if water levels

are incorrect.

Generally the sluice control system is not modified for normal flows down the Canal. The only exceptions to this are:

• Depending on the prevailing weather conditions the set point on the Eastham Pond is lowered to a winter level

between October to April. This is done due to the effect of the changing water level in the River Mersey affecting the

effectiveness of the sluices, as explained in section 4.3. Reducing the water level provides a larger available volume

for the water from the River Weaver to be stored, whilst waiting for the tide to drop in the River Mersey and the

Weaver Sluices to become available for discharging the water;

• If engineering works are being undertaken which require the water level to be altered from its normal level.

The Halcrow Hydraulic Modelling Study provides additional information on how the system operates as does the sluice O&M

Manual.

4.2 Sluice Gate Control

At each location each gate can be set to automatic, manual and off. In manual control the gate is raised and lowered from a

control station located on the top gantry at each sluice position. The height the sluice is opened is read off an indicator board

marked off in metres located on the top gantry.

4 Description of Normal Water Level Control

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The number of sluices in automatic is dependent on the flows down the Canal. The POC arranges for the use of the sluices to be

distributed evenly. Generally the aim is for each sluice to be raised no more than 1000mm as this limits vibration, and therefore

wear, within the sluice. Also to limit possible damage to the Canal embankment, the landside sluices are manually operated by

opening once per month by no more than 300mm, unless all other sluices were fully raised. This sluice is given preferential use

during low flow periods so that automatic operation is tested on a regular basis.

During periods of normal flow all sluices are operated at least once every 4 weeks if they have not been in automatic mode.

During periods of low flow, when the sluices are staunched to conserve water, they are not operated unless to control the water

level. Once flows are experienced down the Canal the sluices are operated to prove their availability. The weather forecast will

be closely monitored during this period so that additional sluices can be operated to prove their availability.

Normally the PLC controls the position of the sluice gate depending on the information it receives from the water level sensors. It

operates as follows:

• PLC reads upstream water level;

• If this is above the set point the system recognises the need to raise the sluice gate;

• A signal is sent to the gate motor controller to run for a fixed period. This period moves the gate a fixed distance;

• Each gate that is set to automatic operation will be operated in turn;

• After a set period, approximately 6 minutes, if the water level is still above the set point a gate will be raised;

• Due to the turbulent flow of water under the gates when they are open the gate can experience high levels of

vibration. This severe vibration occurs at certain heights, generally between 100mm and 250mm above the sill. To

avoid damage to the gate, when in automatic mode, an exclusion zone has been created in which the gate is not

stopped;

• The sluices can be raised a maximum of 2.44m in automatic mode;

• At Weaver Sluices the gates will automatically close when the rising tide level in the River Mersey reaches a pre-set

difference with the water level in the Canal. Otherwise when the water level in the river rises above the water level in

the Canal water will flow into the Canal through the sluices potentially affecting vessel navigation and also allowing

silt to enter the Canal. When these sluice gates are open there is considerable flow across the Canal which

potentially creates a hazard to shipping. These gates can therefore be closed by the POC to allow shipping to safely

pass.

4.3 Effect of Tidal Conditions

For the Eastham Pond section of the Canal the flows through Weaver Sluices are dependent not only on the sluice gates being

raised but also on the water level in the River Mersey. At High Water no flow out of the Canal is possible so if there are high flows

down the Canal into this pond then this water cannot be released until the water level in the river drops. High Water can last for

three hours depending on the tide level and weather conditions.

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5 Description of Operational Control During High Water

Flows

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5.1 Monitoring for High Water Flows

As explained in section 4 the water level on the Canal is continuously monitored. If water levels started to increase this situation

would be identified in a number of ways

• By the SCADA system alarming at the VTS Control Room;

• By the POC. It is part of the operator’s duties to actively monitor weather conditions and water levels in the Canal.

For the weather forecasts they obtain data from the Met Office. The water levels are monitored by checking the

SCADA System outputs which show the water level trend along the Canal, by CCTV located at each sluice, by

discussion with the operators who attend to operate the locks to allow vessels to pass through and by discussion

with ships pilots and captains;

• By the various flood warnings that are issued by the Environment Agency.

5.2 Environment Agency Flood Warning Procedure

In England and Wales the Environment Agency operates a flood warning service in areas at risk of flooding from rivers or the

sea. The system in place is described below. This may change and the Company will modify its procedures to in line with any

flood warning systems implemented in the future.

If flooding is forecast, warnings are issued using a set of three easily recognisable codes.

Each of the four codes indicates the level of danger associated with the warning. The codes are not always used in sequence; for

example in the case of a flash flood, a Severe Flood Warning may be issued immediately, with no other warning code preceding

it. The four codes are:

Flood Alert

Flooding is possible. Be prepared.

Flood Warning

Flooding is expected. Immediate action is required.

Severe Flood Warning

Severe flooding. Danger to life.

MSCC are included in warnings

The system of warnings issued by the Environment Agency may change from time to time. MSCC will keep up to date with

whatever system is in place.

5 Description of Operational Control During High Water Flows

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5.3 Procedure in the Event of Anticipated High Water Flows

When high water flows are anticipated or a Flood Alert is received by the POC the;

a) Operator’s availability will be confirmed and they will be put on standby;

b) Duty Harbour Master will be informed;

c) POC are instructed to continuously monitor the SCADA System, CCTV and liaise with pilots and Ships Masters.

If a Flood Warning or Severe Flood Warning is issued or the POC gains other intelligence the;

a) Duty Harbour Master is informed;

b) Depending on the number of sluices in automatic mode and what the weather conditions are the operators are

instructed to attend site to put additional sluices into automatic mode. They will be instructed to attend on site if all

sluices are made available;

c) Depending on shipping activity and the Canals water level the set point may be set to its lowest level. This will be on the

instruction of the Duty Harbour Master;

d) All vessels wanting to move will be advised that they may not be able to transit the Canal. The POC will liaise with Ships

Captains to discuss at what point transit for the vessel will not be advisable. The following general rules apply:

• Pleasure craft, rowing boats and narrow boats, anything above a total of 1500mm of sluicing is hazardous and they

are not allowed to move;

• Commercial Ships – at approximately a total of 3000mm of sluicing special consideration will be made where size,

draft, available power, manoeuvrability, location of the vessel would be considered. This would be particularly so if

they were swinging downstream of the sluices. The 3000mm is equal to one sluice being nearly fully open and

equates to water flows of approximately 180cumecs.

e) If all sluices are in use then Maintenance Personnel will be called out. In automatic mode the sluices are limited to

opening 2.44m by a limit switch. The maintenance personnel bypass the limit switch allowing the sluice to be raise to

3.05m. This will enable the sluices to be raised to the 3.05m by the local manual electrical control;

f) All sluices are put into automatic apart from the landside sluice. This is left in manual and raised 300mm in order to

reduce possible damage to the canal bank. This sluice will be raised if water flows dictate;

g) If the sluices reach the upper limit on the electrical control system and the limit switch has not been bypassed the

operators can raise them to the maximum height by hand winding if required;

h) If the automatic control system fails in anyway the backup system will be initiated. The time taken to implement

alternative operating methods is as follows:

i. Local Electrical Operation – the time it takes to walk from the shelter on the locks to the sluices, approximately 5

minutes. This is considered the most appropriate location as they will be informed by the POC if a fault develops;

ii. Hydraulic drive – this equipment requires setting up on each individual sluice by two operators. Time to set up 30

minutes. In the event of a Severe Flood Warning or anticipated high flows the equipment will be made ready;

iii. Manual Operation - the time it takes to walk from the shelter to the sluices approx 5min. It takes 27 turns of the

handle to raise the sluice gate 50mm. Winding handles are available at all locations and are located in the Control

Room building.

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i) The operators will report back to the POC that sluices have been raised as required. The Duty Harbour Master will

advise the height the sluices should be raised to. Generally this will be to ensure all sluices, including those in automatic

are raised an equal amount.

5.4 Resources available

• In Respect of the Upper Reaches:

o The operators are Billway Ltd and S&F. Between them they have 29 personnel. They are on 24 hour call

for the operation of the locks for shipping so attend each site on a daily basis. In the event of a predicted

flood event they would be put on standby and then called to site as required, but prior to urgent action

being taken if there is a sluice failure. They each have three operators on call at all times. See section 5.5

for an explanation of arrangements if high water flows were being predicted;

o MSCC Maintenance Personnel. There are ten personnel available who can operate the sluices in the event

of a sluice failure. Seven operators are available at any time.

• Weaver Sluices. These are operated by MSCC Maintenance Personnel. There are up to seven personnel available

who can operate the sluices in the event of a sluice failure.

5.5 Communication

The following arrangements are in place for contacting operators in an emergency.

The operators are in regular contact with the POC via mobile phone during the normal course of the day to make arrangements

for the operation of the locks. If high water flows are predicted the operator will be put on standby at this point. The POC and

operator will agree who is to attend which site. Both the POC and operator will monitor the local roads via local radio to ensure

that there will be no delay in attending the sluices. If there is a special event occurring in the location then the operator would be

requested to attend the sluice at an earlier stage in the process. This will depend on the particular circumstances prevailing at the

time. Once at the site in addition to mobile phone communication there are land line telephones at the operator shelters and in

the Sluice Control Room. VHF radio is available at each lock.

All locations can be accessed from either side of the Canal so that if for some reason access is blocked on one side then access

can be gained from the other side.

5.6 Training

All operators and MSCC maintenance personnel are given training enabling them to operate the sluices in the various back up

methods available.

5.7 Testing of Backup Procedures

This is undertaken as part of the routine maintenance, see Section 6.

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6 Routine Maintenance and Major Maintenance/Capital

Renewal Programme

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6.1 Routine Maintenance

Peel Ports operate a comprehensive maintenance planning system which was introduced in 2004. It is used to control the

frequency of inspections, what to inspect and provides a means of recording the results of the inspections and other work

undertaken on the asset.

Table1 below shows how the various components of the sluices are structured for the planned maintenance system, in this case

Mode Wheel. The other sluices are similar.

Table 2, the Work Specifications, detail what type of inspection and maintenance is undertaken as part of the planned

maintenance work.

Equipment No (Plant) Description

S/MW/SLUICE Mode Wheel Flood Sluice Gates

S/MW/SLUICE/ESE Mode Wheel Sluice Emergency Equip

S/MW/SLUICE/GATE/1 Mode Wheel Flood Sluice Gate No1




S/MW/LCK/SCADA/SYS Mode Wheel Lock Sluice Control System (SCADA System)

Table 1 – Mode Wheel Sluice Assets Covered by the Planned Maintenance System

PM No Work Spec Cat Work Specification Description

PM004802 Contractor SCADA System Inspection – 52 WEEKLY

S/PM000923 Mechanical Sluice Gate Machinery - Mechanical Inspection - (A) Service ALL POSITIONS 8 WEEKLY

S/PM000922 Mechanical Sluice Gate Machinery - Mechanical Inspection - (B) Service 26 WEEKLY

PM005055 Lubrication Flood Sluice Chain Lubrication – (A) Service 52 WEEKLY

PM005079 Electrical Electrical (General) - Motor Maintenance Service - (A) Service ALL POSITIONS 8 WEEKLY

PM005078 Electrical Electrical (General) - Motor Maintenance - (B) Service 26 WEEKLY

S/PM002243 Condition Monitoring

Sluice Engineers Inspection (Upper Lock Sluices) - (A) Service ALL POSITIONS 8 WEEKLY

Table 2 – Mode Wheel Sluice Planned Maintenance Work Specifications

Included in the maintenance regime are specific tests to confirm the sluices availability. These are;

• Normal Operation

The automatic change over of the electrical supply. This is undertaken 3 monthly;

• Hydraulic drive

This is tested at each location annually by installing, operating and raising a sluice gate. All sluices are checked to ensure

that when the drive is fitted to the manual winding shaft it disables the electrical drive;

6 Routine Maintenance and Major Maintenance/Capital Renewal

Programme

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• Manual operation

Manual operation is tested at each location annually. The winding handles are securely stored in the control room. All

sluices are checked to ensure that when the winding handle is fitted to the manual winding shaft it disables the electrical

drive.

In addition there is a programme of debris clearance. This includes:

• Mode Wheel – system of barrages to contain the considerable amount of debris allowed to transit down from the

Rivers Irwell, Irk and Medlock that collect at Mode Wheel locks, generally in front of the sluices. The debris is

collected by a bespoke vessel that corrals the debris to enable a 360° excavator to recover and deposit in skips for

disposal to landfill;

• Remaining sluices – debris clearance as and when by MSCC’s floating crane;

• Woolston Weir – six monthly debris clearance by a diving team;

All maintenance schedules are available for inspection at the Companies Runcorn Workshops.

6.2 Major Maintenance

A continual programme of major maintenance has been in place for many years. This remains in place and includes:

6.2.1 Refurbishment of the sluice operating machinery when the sluice is renewed under the capital renewal programme;

6.2.2 Comprehensive annual sluice gate inspections and the implementation of any required remedial work. These inspections

determine the order in which the sluices would be replaced;

6.3 Capital Renewal Programme

Since 2007 a capital renewal programme of major components has been implemented. This includes sluice gates, counter

balances and top gantries. To date (December 2010) the sluices replaced during this programme of work are:

• Irlam No1 - 2007

• Barton No4 - 2009

• Weaver No2 – 2007

• Weaver No3 – 2010

Weaver No5 is currently being replaced and will be completed in the first quarter of 2011.

Whilst a gate is being renewed the sluice is unavailable for approximately three months. A maximum of one sluice at each

location will be unavailable during this replacement programme. The work would normally be undertaken between April and

September of each calendar year.

The control system hardware and the SCADA system are also in the process of being replaced and this work is expected to be

substantially completed early January 2011.

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7 Reliability of Sluice Operation

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7.1 Reliability Analysis

The reliability of the sluice operation can be considered in terms of the different components of the operation. These are;

• Failure of the sluice mechanically, electrically or structurally;

• Failure due to no operator available.

Det Norske Veritas (DNV) have undertaken a reliability analysis of the complete sluice operation to determine the probability of

the sluices not operating normally.

The chance of the sluice system at each of the sites on the Canal failing to operate adequately is explored through reliability

analysis. Reliability analysis builds up the probability of the failure of the system to perform normally by considering all potential

causes of failure in the system components. These components are diverse and include:

• physical components such as the gate motors;

• external infrastructure such as the power supply;

• human sources such as decision making.

A review group comprising representatives from Peel Ports, Peel Land and Property, DNV and AECOM considered the failure

modes and agreed the factors that would contribute to the failure of the sluice system. The following identifies the various failure

modes considered and the assumptions agreed by the review group.

Note: For standard elements such as gear boxes readily available reliability data has been used.

Table 3 is taken from the DNV Report showing the results of the reliability assessment.

For a location with a set of four sluice gates

Probability of all four sluice gates opening on demand 92.8%

Probability of at least 3 gates opening on demand 99.11%

Probability of at least 2 gates opening on demand 99.255%

Probability of at least 1 gate opening on demand 99.256%

Table 3- Results of reliability assessment

The assumptions which have lead to these results can be found in the DNV Report, ‘MSC Final Report’ dated 28th October

2010.1

The analysis has shown that, for the following reasons, the sluice reliability is very high:

• Each set of sluices incorporates some redundancy in the form of multiple individual sluice gates;

• There is redundancy at each location in terms of monitoring systems that detect the water levels and the state of operation of the sluice gates;

• There is redundancy at each location in terms of the systems for operating the gates, including the option of purely manual, unpowered control;

1 Sluice Gate Reliability of the Manchester Ship Canal, Reference 244 27814, 28th October 2010 – Det Norse Veritis

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• The sluices are used in routine canal operations to maintain the operating water levels, which indicate a level of testing that far exceeds typical dedicated flood defence systems.

7.2 Blockage of sluices and weirs by debris

Blockage of a sluice does not occur in the same way as say a culvert blockage. It will build up over time and is monitored by

regular inspections of the sluices and weirs. It is in fact most likely to be most significant after a flood with the risk of not being

able to close the sluice gate being the main problem. For this reason the probability of failure due to a blockage has been

discounted.

8 Working Arrangement

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Peel and the Environment Agency are committed to working together. The MSCC can be considered a Professional Partner with

the Environment Agency. There are a number of ways in which this working relationship can develop:

1. Working together on ensuring the Hydraulic Model is updated as new information and data becomes available;

2. Sharing of data relevant to water level control and that of the rivers that feed into the Ship Canal;

3. Continue with regular meetings to discuss matters of mutual interest;

4. Ensuring that the Local Authorities whose land through which the Canal runs through have a proper understanding of

the flood risks so that appropriate development decisions can be taken.

8 Working Arrangements

mscc water level control - operational protocol final 25 -1-11€¦ · the sluice control system is...

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