EAST RENFREWSHIRE COUNCIL
ENVIRONMENT DEPARTMENT
ROADS & TRANSPORTATION SERVICE
FLOOD PREVENTION AND LAND DRAINAGE
(SCOTLAND) ACT 1997
Report on measures to be taken to prevent or mitigate flooding of
non-agricultural land in East Renfrewshire
November 2001
Director: Andrew J Cahill, BSc (Hons)
Head of Roads and Transportation : Joseph Devine, BSc, MSc, Ceng, MICE
Refuge House, 17/19 Gauze Street, Paisley, PA1 1ES
Phone: 0141 577 3417
FAX 0141 577 3414
2
CONTENTS
Section
Page No.
1
Introduction
2
2.
Legislative Background and Responsibilities
3
3.
Main Flood Issues since 1999
4
4.
Assessment of Watercourses
5
4.1
4.2
4.3
5.
Flood Alleviation and Mitigation
5.1
5.2
5.3
6.
8
Development Control
Flood Appraisal Groups
Catchment Management
Finance and Resources
6.1
6.2
7.
Inspections
Maintenance
Monitoring
10
Management
Finance and Future Resources
Conclusions and Recommendations
APPENDICES
A.
Flood Register
B.
Culvert Screen Inspection Programme
11
3
1.
Introduction
1.1
This report has been prepared by the Roads and Transportation Service of the
Environment Department of East Renfrewshire Council, who are responsible for
implementing the statutory provisions of the Flood Prevention (Scotland) Act 1961
(1961 Act), as amended by the Flood Prevention and Land Drainage (Scotland) Act
1997 (1997 Act).
1.2
It is a statutory requirement of the 1997 Act for the Council to produce and publish a
biennial report, recording the incidences of flooding which have occurred since the
publication of the previous report and detailing the actions undertaken by the Council
to alleviate further flooding of non-agricultural land. The previous statutory report
was published in November 1999.
4
2.
Legislative Background & Responsibilities
2.1
Flood Prevention (Scotland) Act 1961
This Act gave Local Authorities discretionary powers to take such steps, as they
considered necessary to mitigate or prevent flooding in non-agricultural land. Where
works, other than maintenance and management, were proposed a formal Flood
Prevention Scheme had to be submitted to central government for approval.
The 1961 Act did not place riparian owners under any obligation to contribute
towards the cost of any watercourse improvement works. It did give them
considerable protection concerning the use of their own section of watercourse.
2.2
Land Drainage (Scotland) Acts
The provisions of these Acts relate to agricultural land.
2.3
Sewerage (Scotland) Act 1969
This places a statutory duty on the Sewerage Authority (West of Scotland Water)
regarding domestic sewage and surface water run-off from roofs and paved areas
within the curtilege of premises.
2.4
Flood Prevention and Land Drainage (Scotland) Act 1997
The 1997 Act amends the Flood Prevention (Scotland) Act 1961 and now requires
local authorities to undertake certain duties in relation to watercourses and their
management. These duties include: a)
The assessment of watercourses in their area from time to time to ascertain if
they are in a condition which is likely to cause flooding of non-agricultural
land within or outwith the councils area.
b)
To maintain the efficiency of flood defences and watercourses in order to
substantially reduce the likelihood of flooding.
c)
To publish a report every two years on the actions taken and further measures
proposed and to record the occurrences of flooding since the date of the
previous report.
The wording of the 1997 Act is vague; there is no definition of ‘from time to time’ or
of ‘substantially reduce the likelihood of flooding’. The 1997 Act does not relieve the
individual riparian owners of their primary duty to take measures to mitigate or
prevent flooding of their property.
The 1997 Act does not prescribe the format for assessing watercourses. Some
councils have adopted a do minimal view, while others have implemented full scale
modelling.
5
3.
Main Flood Issues Since 1999
3.1.
There have been no recorded instances of serious flooding events associated with
watercourses since October 1999.
3.2.
A major rainfall event occurred at the end of November 1999, lasting for a number of
days. The intensity of the rainfall was not unusual but the prolonged nature of the
storm led to saturation of the catchment across the whole of the Council area. The
timing of the storm also coincided with a large fall of leaves, which contributed to the
debris loading of the watercourses.
3.3.
A number of culvert screens became blocked. Water levels in the watercourses
became too high to allow road drainage systems to discharge, leading to flooding on
roads. The culvert screens were inspected before, during and after the storm and
blockages were cleared as soon as practicably possible. Most of these were dealt with
by the Council, particularly by Roads and Transportation Service and the Highways
Contracting Unit of the Department of Commercial Operations.
3.4.
High water levels particularly affected the Broom Burn, the Shaw Linn, the Merry
Burn at Brooklea, the Aurs Burn and the Eaglesham Burn. Other minor watercourses
were also affected.
3.5.
The table in Appendix A details all of the recorded flooding events in East
Renfrewshire since October 1999.
3.6.
Most instances of localised flooding have generally been associated with debris buildup in watercourses, particularly at culvert screens.
3.7.
The table does not include flooding incidences relating to road drainage, eg blocked
road gullies.
6
4.
Assessment of Watercourses
4.1
Inspections
4.1.1. The 1997 Act requires the Council to undertake assessments of the watercourses
‘from time to time’. The first biennial report, published in 1997, listed the major and
significant watercourses within East Renfrewshire and noted the intention to
undertake assessments of these watercourses. The second report published in 1999
listed the watercourses where inspections had been undertaken.
4.1.2. The assessment involved walking the length of each watercourse, within the urban
areas, noting existing and potential blockages, taking photographs and marking up
location plans. Incidences of previous flooding were also noted on the location plans.
4.1.3. In general the watercourses have been found to be in a ‘fair’ condition. There are
however areas within individual watercourses which are severely restricted, usually
by fallen trees and other debris. It should be noted that the 1997 Act does not oblige
the Council to undertake extensive clearing of watercourses. Action need only be
taken to ‘substantially’ reduce the likelihood of flooding. Riparian owners are still
responsible defending their own properties from flooding.
4.1.4. These initial survey reports shall be used as the basis for comparison with future
surveys. The 1997 Act only requires the watercourses to be inspected from ‘time to
time’. It is evident from the initial survey that some watercourses would benefit from
a more frequent inspection than others.
4.1.5. A number of grills and screens have been identified during the watercourse surveys,
on major and minor watercourses. An inspection programme has been developed for
all of the known screens, with a minimum period between inspections identified for
each grill. The interval between inspections is based on previous frequencies of
blockages and the likelihood of serious flooding problems at each locale. Heavy
rainfall events lead to an increased frequency of inspection. Poorly designed
headwalls and screens are responsible for the large proportion of flooding problems.
4.1.6. Other known blockage locations have been identified and have been inspected on a
reactive basis after storm events. The inspection list has been expanded considerably
over the last two years.
7
4.2
Maintenance
4.2.1
A number of the culvert screens have been cleared by East Renfrewshire Council,
Department of Commercial Operations, Highways Contracting Unit. Where debris
build-up is identified during an inspection a Works Order is issued immediately for
the debris to be cleared.
4.2.2
The Highways Contracting Unit also deal with flooding incidences during and after
storm events, including clearing road gullies and removing debris from culvert
screens and other known blockage locations.
4.2.3
A section of the Merry Burn between Fenwick Road and Ledi Road was cleared of
silt and debris in March 2001, using mechanical excavators. This method proved to be
successful but is costly and requires consultation with the Scottish Environmental
Protection Agency (SEPA). The prime concern of SEPA is with water quality and its
agreement is required prior to undertaking any work in the watercourses.
4.2.4
Silt was also removed from a small section of the Braidbar Burn in Barrhead using a
vacuum system. This method proved useful in removing silt but had limited use in
dealing with larger debris.
4.2.5
These two trials have been used to provide base costs which can be used to estimate
future works. The small section of Merry Burn cost over £5,000 to clear, while the
removal of the silt from the Braidbar Burn cost in the region of £1,200.
4.2.6
Contact has been made with BTCV (formerly the British Trust for Conservation
Volunteers). BTCV are keen to set up local groups within East Renfrewshire who
may take an interest in looking after stretches of watercourses. This partnership
approach has proved successful in other areas and is worthy of further exploration.
8
4.3
Monitoring
4.3.1. A programme of culvert screen inspections has been implemented, with the frequency
of inspection varying from monthly to quarterly, depending on the known history of
individual screens. More frequent inspections are undertaken during and after major
rainfall events. (Appendix B)
4.3.2. Other known problem locations have also been added to the inspection programme.
The locations have been linked to the Council GIS system.
4.3.3. The results of the inspections are recorded on a computer database (MS Access)
within the Roads and Transportation Service.
4.3.4. Incidences of flooding are also held on another computer database (MS Access). The
locations have been linked to the Council GIS system.
.
9
5.
Flood Alleviation and Mitigation
5.1
Development Control
5.1.1
East Renfrewshire Council, Roads and Transportation Service provides the Planning
Service with advice on flooding and drainage issues, in addition to road network
issues, with regard to development control and urban drainage.
5.1.2
Planning issues are covered under National Planning Policy Guideline 7 (NPPG7)
published by the Scottish Executive. Regular consultations take place between the
Council, Developers, West of Scotland Water and the Scottish Environmental
Protection Agency (SEPA).
5.1.3
The drainage implications for all new developments are therefore considered in
relation to their effect on the watercourses adjacent and downstream of the
development.
5.1.4
Culvert headwalls and inlet screens are to be designed to the recommendations of
CIRIA Report 168 ‘Culvert Design Guide’. Correctly designed headwalls and inlets
will reduce the likelihood of blockages occurring and adopting these guidelines as
‘good practice’ will ensure that a consistent approach is adopted across the Council
area.
5.1.5
Developers are generally asked to provide Flood Risk Assessments to prove that the
proposed development will in itself not be at risk of flooding and that it will not
increase the likelihood of flooding downstream of the site.
5.2
Flood Appraisal Groups
5.2.1
East Renfrewshire Council participates in the White Cart Flood Appraisal Group
(FAG) on a regular basis. Although flooding of the White Cart Water does not cause
any great concern within East Renfrewshire it is a major problem within Glasgow and
Renfrewshire.
5.2.2
The FAG has appointed Babtie Group to develop a model for the White Cart Water
and East Renfrewshire Council has given financial support to this initiative.
5.2.3
The FAG provides a forum for the discussion of flooding and drainage related
problems. The FAG can make recommendations to the Council but has no
authoritative power to force the Council to implement them. East Renfrewshire
Council recognises the value of the FAG and continues to be supportive of its work.
5.3
Catchment Management
5.3.1
As stated above East Renfrewshire Council uses the guidelines of NPPG7 to control
development within the council boundary. Guidance notes produced by SEPA and
WoSW are also used to ensure that Best Management Practices are employed within
each development.
5.3.2
Examples of the above include incorporating attenuation tanks within drainage
systems to control discharge into watercourses and using swales to again control
discharge but in an environmentally friendly way.
10
5.3.3 East Renfrewshire Council is represented on the Flooding Working Group of the
Society of Chief Officers for Transportation in Scotland (SCOTS). This forum
provides the ideal opportunity for Local Authorities to disemminate information
across a wide range of issues and to develop guides to Best Practice.
11
6.
Finance and Resources
6.1
Management
6.1.1
The 1997 Act places some onerous responsibilities on the Council in terms of
watercourse management. These include the inspection and maintenance of
watercourses, the production of reports and the maintenance of a flood register.
6.1.2
The 1997 Act is however vague in determining what exactly is to be done. Case Law
will eventually establish the meaning of the various clauses within the legislation.
Until then each Council will have to determine its own priorities and make available
the resources to implement them.
6.1.3
The routine inspection of the culvert screens, the clearing of the screens, the
maintenance of the flood register and the inspection of the watercourses have been
undertaken using resources of the Roads and Transportation Service Revenue budget.
6.1.4
Development control is also funded from the Revenue budget.
6.1.5
Any major works involving installation of new culvert screens or re-channelling of
sections of watercourse would be classed as improvements and would be funded from
the Capital budget.
6.1.6
Any named Flood Prevention Scheme would also require to be funded from the
Capital budget.
6.2
Finance and Future Resources
6.2.1
Funding will be required for the ongoing culvert screen inspections, clearing of
screens and for maintaining the flood register.
6.2.2
If Capital funding is made available, then the installation of improved culvert screens
to the recommendations of CIRIA Report 168 can be carried out.
6.2.3
If Revenue funding is made available then the continued inspection of the lesser
watercourses and culverts can be undertaken. The route and construction of some
culverts are unknown and need to be traced using CCTV equipment. There are a
number of known problem areas associated with these minor watercourses.
6.2.4
The wholesale clearing of watercourses is not an option. Clearing of known problem
areas, with the co-operation of the riparian owners would require a further increase in
funding.
6.2.5 At present there are no plans to develop a Flood Prevention Scheme for any
watercourse within East Renfrewshire.
12
7.
Conclusions and Recommendations.
7.1.
Although there have been no major flooding incidents within East Renfrewshire the
1997 Act places some onerous statutory duties on the Council.
7.2.
Revenue funding will be sought to improve culvert screen inspection, screen clearing
and maintenance of the flood register.
7.3.
Capital funding will be sought to replace culvert screens to current recommendations
and for improvements to watercourses.
7.4.
The Roads and Transportation Service will continue to co-ordinate responses to
flooding incidents through the Highway Construction Unit.
APPENDIX A
APPENDIX A
FLOOD REGISTER
FLOOD REGISTER
Ref
E27
E42
E49
E50
E51
E52
E53
E54
E55
E56
E57
E58
E59
E60
E61
E62
E63
E64
E65
E66
E67
E68
E69
E70
Watercourse
Bridgebar Burn
Bridgebar Burn (tributary)
Merry Burn (trib)
Broom Burn
Broom Burn
Broom Burn
Eaglesham Burn
Capelrig Burn (trib)
Shaw Linn
Bagabout Burn
Broom Burn
Broom Burn
Broom Burn
Broom Burn
Broom Burn
Capelrig Burn
Capelrig Burn
Shaw Linn
Merry Burn (trib)
Eaglesham Burn
Brackenrigg Burn
Plumb Burn
Bridgebar Burn
Capelrig Burn (trib)
Location
Quarry Road
Hillside, Barrhead
Brooklea Drive
Windsor Avenue
Mearns Road
Dunbeath Avenue
Eaglesham
Greenlaw Drive
Broomvale Drive
Robslee Crescent
Mearns Road
Dunbeath Avenue
Windsor Avenue
Lochbroom Drive
Leslie Avenue
Capelrig Road
Harvie Avenue
Newtonlea Avenue
Brooklea Drive
Gilmour Steeet
Brackenrigg Crescent, waterfoot
Waterfoot Road, waterfoot
Paisley Road, Dealston Road
Stewarton Road
Date 1
30/11/99
03/12/99
28/11/99
28/11/99
30/11/99
28/11/99
03/12/99
30/11/99
30/11/99
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
29/10/00
Date 2
30/11/99
30/11/99
30/11/99
APPENDIX B
CULVERT SCREEN
INSPECTION PROGRAMME
Grill No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Location
Arthurlie Avenue
Aurs Bridge
Broomburn Culvert
Burnhouse Farm Culvert
Burnside Gardens
Caplet Culvert
Castlegate
Eglinton Arms Hotel
Firwood Court
Gatehouse Culvert
Glen Doll Road
Glen Finlet Road
Greenfield Bridge
Kelburn Street Culvert
Kirkton Burn Bridge
Muirend Playing Fields
Maple Avenue
Newton Grove
Near Fingalton Bridge
No 207 Ayr Road
No 160 Busby Road
No 155a Kilpatrick Gardens
Quarry Road
Shilford Culvert
Neidpath Road West
Westacres Road - West
Westacres Road - East
Strathaven Road
Park South of Roger
Moorhill Road
Broomley Lane
Gladstone Avenue
Newton Court
Belford Grove
Ochil Drive
Robslee Crescent
Description
Galvanised steel.
Galvanised steel.
Galvanised steel
Galvanised steel.
Mild steel.
Galvanised steel.
Galvanised steel.
Galvanised steel.
Mild steel.
Galvanised steel
Mild steel.
Galvanised steel.
Galvanised steel.
Galvanised steel.
Frequency
Monthly
Monthly
Monthly
Quarterly
Monthly
Monthly
Quarterly
Monthly
Monthly
Quarterly
Quarterly
Quarterly
Quarterly
Monthly
Monthly
Mild steel.
Quarterly
Mild steel.
Quarterly
Galvanised steel. Quarterly
Galvanised steel. Quarterly
Mild steel.
Quarterly
Mild steel
Quarterly
Mild steel
Monthly
Mild steel
Monthly
Galvanised steel Quarterly
Mild steel
Quarterly
Galvanised steel Monthly
Galvanised steel Monthly
Steel Mesh
Quarterly
Galvanised steel Monthly
Galvanised steel Monthly
Footbridge & Pipe Monthly
Galvanised steel Quarterly
Galvanised Steel Quarterly
Galvanised Steel Quarterly
Masonry Arch
Monthly
Sewage Pipe
Monthly