Design Manual for Roads and Bridges
Drainage
Inspection & Assessment
CS 551
Drainage surveys
(formerly SD 15/03)
Revision 0
Summary
This document contains the requirements for highway drainage surveys.
Application by Overseeing Organisations
Any specific requirements for Overseeing Organisations alternative or supplementary to those given in this document
are given in National Application Annexes to this document.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Highways England team. The email address for all enquiries and feedback is:
Standards_Enquiries@highwaysengland.co.uk
This is a controlled document.
CS 551 Revision 0
Contents
Contents
Release notes
4
Foreword
Publishing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contractual and legal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
5
5
Introduction
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assumptions made in the preparation of this document . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mutual recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
6
6
6
Abbreviations
7
Terms and definitions
8
1. Scope
Aspects covered
Implementation
Use of GG 101 .
Health and safety
.
.
.
.
11
11
11
11
11
2. General requirements
Scope of works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Traffic management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
13
13
3. Validation survey
Survey requirements . . . . . . . .
Scope of survey . . . . . . .
Survey data round-tripping .
Survey equipment . . . . . .
Method of survey . . . . . . .
Termination of survey . . . .
Quality control requirements . . .
Surveyor competency . . . .
Survey method quality control
Reporting requirements . . . . . .
Data submission . . . . . . .
Survey data . . . . . . . . . .
Photographs . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
14
14
14
14
14
15
16
16
16
16
16
16
16
17
4. Priority asset survey
Survey requirements . . . . . . . .
Scope of survey . . . . . . .
Survey data round-tripping .
Desk study . . . . . . . . . .
Survey equipment . . . . . .
Method of survey . . . . . . .
Quality control requirements . . .
Surveyor competency . . . .
Survey method quality control
Reporting requirements . . . . . .
Data submission . . . . . . .
Survey data . . . . . . . . . .
Photographs . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
18
18
18
18
19
20
20
21
21
21
21
21
21
22
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
CS 551 Revision 0
5. Filter drain condition survey by GPR
Survey requirements . . . . . . . . . .
Scope of survey . . . . . . . . .
Survey data round-tripping . . .
Survey equipment . . . . . . . .
Method of survey . . . . . . . . .
Interruption of survey . . . . . . .
Abandonment of survey . . . . .
Quality control requirements . . . . .
Surveyor competency . . . . . .
Survey method quality control . .
Reporting requirements . . . . . . . .
Data submission . . . . . . . . .
Report . . . . . . . . . . . . . . .
Survey data . . . . . . . . . . . .
Photographs . . . . . . . . . . .
Contents
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
23
23
23
23
24
24
24
25
25
25
25
26
26
26
29
30
6. All assets condition and connectivity survey
Survey requirements . . . . . . . . . . . . . . .
Scope of survey . . . . . . . . . . . . . .
Survey data round-tripping . . . . . . . .
Desk study . . . . . . . . . . . . . . . . .
Survey equipment . . . . . . . . . . . . .
Method of survey . . . . . . . . . . . . . .
Interruption of survey . . . . . . . . . . . .
Quality control requirements . . . . . . . . . .
Surveyor competency . . . . . . . . . . .
Survey method quality control . . . . . . .
Reporting requirements . . . . . . . . . . . . .
Data submission . . . . . . . . . . . . . .
Survey data . . . . . . . . . . . . . . . . .
Photographs . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
31
31
31
31
32
32
33
36
36
36
36
37
37
37
37
7. Pipework and chambers defect survey by CCTV
Survey requirements . . . . . . . . . . . . . . . . .
Scope of survey . . . . . . . . . . . . . . . .
Survey data round-tripping . . . . . . . . . .
Survey equipment . . . . . . . . . . . . . . .
Method of survey - pipework CCTV . . . . . .
Method of survey - chambers . . . . . . . . .
Interruption of survey . . . . . . . . . . . . . .
Abandonment of survey . . . . . . . . . . . .
Quality control requirements . . . . . . . . . . . .
Surveyor competency . . . . . . . . . . . . .
Survey method quality control . . . . . . . . .
CCTV picture quality control . . . . . . . . . .
Reporting requirements . . . . . . . . . . . . . . .
Data submission . . . . . . . . . . . . . . . .
Survey data . . . . . . . . . . . . . . . . . . .
Video recordings . . . . . . . . . . . . . . . .
Photographs . . . . . . . . . . . . . . . . . .
Report (optional) . . . . . . . . . . . . . . . .
CAD drawings (optional) . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
39
39
39
39
40
41
42
43
44
44
44
45
45
45
45
46
47
47
47
48
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
2
CS 551 Revision 0
8. Pipework geometric survey by laser profiler
Survey requirements . . . . . . . . . . . . . . .
Scope of survey . . . . . . . . . . . . . .
Survey data round-tripping . . . . . . . .
Survey equipment . . . . . . . . . . . . .
Method of survey . . . . . . . . . . . . . .
Interruption of survey . . . . . . . . . . . .
Abandonment of survey . . . . . . . . . .
Quality control requirements . . . . . . . . . .
Surveyor competency . . . . . . . . . . .
Survey method quality control . . . . . . .
Reporting requirements . . . . . . . . . . . . .
Data submission . . . . . . . . . . . . . .
Report . . . . . . . . . . . . . . . . . . . .
Survey data . . . . . . . . . . . . . . . . .
CAD files . . . . . . . . . . . . . . . . . .
Contents
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
49
49
49
49
49
49
50
50
50
50
50
50
50
50
51
51
9. Normative References
52
10. Informative References
53
Appendix A. Example schedule of requirements
A1 General requirements . . . . . . . . . . . . . . . . . . .
A2 Survey requirements . . . . . . . . . . . . . . . . . . . .
A2.1 General . . . . . . . . . . . . . . . . . . . . . . .
A2.2 Pipework and chambers defect survey by CCTV
A3 Reporting requirements . . . . . . . . . . . . . . . . . .
A3.1 General . . . . . . . . . . . . . . . . . . . . . . .
A3.2 Pipework and chambers defect survey by CCTV
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
54
54
54
54
55
55
55
55
Appendix B. Drainage condition grade quick assessment
B1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B2 Structural and service condition . . . . . . . . . . . . . . . . .
B3 Asset grouping . . . . . . . . . . . . . . . . . . . . . . . . . .
B4 Excluded assets . . . . . . . . . . . . . . . . . . . . . . . . .
B5 Condition grade quick assessment definitions and examples
B5.1 Chambers . . . . . . . . . . . . . . . . . . . . . . . . .
B5.2 Gullies . . . . . . . . . . . . . . . . . . . . . . . . . . .
B5.3 Inlets and outlets (with formal structure) . . . . . . . .
B5.4 Inlets and outlets (without formal structure) . . . . . .
B5.5 Pipes . . . . . . . . . . . . . . . . . . . . . . . . . . .
B5.6 Filter drains . . . . . . . . . . . . . . . . . . . . . . . .
B5.7 Ditches . . . . . . . . . . . . . . . . . . . . . . . . . .
B5.8 Enclosed channels . . . . . . . . . . . . . . . . . . . .
B5.9 Open channels . . . . . . . . . . . . . . . . . . . . . .
B5.10 Grassed channels . . . . . . . . . . . . . . . . . . . .
B5.11 Ponds . . . . . . . . . . . . . . . . . . . . . . . . . .
B5.12 Ancillaries . . . . . . . . . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
57
57
57
57
58
59
59
61
64
67
70
73
76
79
81
84
86
88
3
.
.
.
.
.
.
.
.
.
.
.
.
.
.
CS 551 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Jun 2019
CS 551 replaces SD 15/03. The full document has been re-written to make it
compliant with the new Highways England drafting rules.
4
CS 551 Revision 0
Foreword
Foreword
Publishing information
This document is published by Highways England.
This document supersedes SD 15/03 of the Manual of Contract Documents for Highway Works, which
is withdrawn.
Contractual and legal considerations
This document forms part of the works specification. It does not purport to include all the necessary
provisions of a contract. Users are responsible for applying all appropriate documents applicable to
their contract.
5
CS 551 Revision 0
Introduction
Introduction
Background
This document provides the requirements for the specialist activity of surveying highway drainage
systems by a number of different methods. The selection of the most appropriate survey method is
detailed in CD 535 [Ref 1.N].
SD 15/03, and accompanying parts, set out a specification, notes for guidance and a method of
measurement, for surveying drainage pipework using Closed Circuit Television (CCTV). Since its
publication in 2003 the Overseeing Organisations have developed national drainage data management
systems. In order to expedite the population of these systems with drainage asset inventory and
condition information, new survey methods have been researched and developed that are both quicker
and lower cost than CCTV survey, and cover more drainage asset types than just pipework. Some of
these drainage survey methods were introduced in IAN 147/12 with supporting guidance notes
providing further detail on their application. HD 217/17 introduced the use of ground penetrating radar
(GPR) for surveying the condition of combined surface and sub-surface filter drains. The requirements
for these various drainage survey methods are now brought together and updated in this one
document, superseding the previous publications. The method of measurement of drainage surveys is
retained within the MCHW Volume 5 Series 9000 [Ref 5.N].
Assumptions made in the preparation of this document
The general requirements in GG 101 [Ref 3.N] apply to this document.
Mutual recognition
Where there is a requirement in this document for compliance with any part of a "British Standard" or
other technical specification, that requirement may be met by compliance with the Mutual Recognition
clause in GG 101 [Ref 3.N].
6
CS 551 Revision 0
Abbreviations
Abbreviations
Abbreviations
Abbreviation
Definition
CCTV
Closed circuit television
CSA
Cross-sectional area
DDMS
Drainage data management system
GIS
Geographic information system
GPR
Ground penetrating radar
GPS
Global positioning system
LiDAR
Light detection and ranging
7
CS 551 Revision 0
Terms and definitions
Terms and definitions
Terms
Term
Definition
All assets condition and connectivity survey
A survey to determine the inventory, asset level
condition and connectivity of all drainage assets in
a drainage system.
NOTE: Also known as connectivity survey.
Axis of drain
A longitudinal line projected centrally along the
inside of the drain (pipework or culvert).
Blockage
An obstruction within the drainage system.
Chamber
Access point that can be a manhole, catchpit or
other structure as defined in CD 535 [Ref 1.N].
Confined space
Any place, including a chamber, trench, pipework,
culvert or similar space where, by reason of its
nature, there is a foreseeable risk of asphyxiation,
loss of consciousness due to increased body heat,
drowning, or serious injury from fire or explosion.
Continuous defect
A longitudinal pipework defect.
Data round-tripping
The process carried out in an area of existing data
that ensures one-version-of-the-truth of the
drainage inventory and condition data is
maintained on the DDMS, by downloading the
available data before a survey commences, and
then checking, updating or adding to it in the field,
before uploading it back to the DDMS, including
any unchanged data, replacing the previous
version of the data on the DDMS.
Drainage asset
An individual component within a drainage system,
such as a gully, pipe, ditch or pond.
Drainage data management system
Overseeing Organisation's primary database for
managing information concerning drainage assets
and flooding.
Drainage highway catchment
A group of all the drainage systems and the
adjacent land they drain, between two
geographical high points of the highway network.
NOTE 1: Both carriageways of a dual carriageway
are considered part of the same catchment, but
risks can be assessed separately for each
carriageway.
NOTE 2: A drainage highway catchment can
include one or more drainage systems.
Drainage system
A group of drainage assets that are directly or
indirectly connected to each other, within a single
drainage highway catchment.
NOTE: Each individual drainage asset is part of
only one drainage system.
8
CS 551 Revision 0
Terms and definitions
Terms (continued)
Term
Definition
Filter drain condition survey by ground
penetrating radar
A survey of the service condition due to sediment
contamination of the filter medium of combined
surface and sub-surface drains, and other forms of
filter drain, including the use of ground penetrating
radar (GPR).
Forced ventilation
The procedure of venting the drainage system by
removing a number of chamber covers and using
ducting, air jets and fans to force air into the
system to purge potentially dangerous gases that
have accumulated within the system.
Node
Manhole, catchpit, inspection chamber, outlet,
gully, rodding eye or any other point from which the
drainage survey commences or terminates.
Pan and tilt camera
A self-propelled camera with a directionally
adjustable lens.
Pipework and chambers defect survey by
closed circuit television
An inventory, condition and detailed defects survey
of pipework and the associated chambers and
gullies, including the use of a closed circuit
television (CCTV) camera.
NOTE: Also known as CCTV survey.
Pipework geometric survey by laser profiler
A survey to determine the pipework internal
circumferential geometry, including the use of a
laser profiler in association with a CCTV survey.
Pre-cleansing
The removal of silt and debris prior to the
commencement of the drainage survey.
Priority asset
An outfall or soakaway that presents a risk of
pollution, or a culvert that presents a risk of
flooding.
Priority asset survey
A survey in areas where the highway drainage
system is unknown or uncertain, in order to locate
the outfall or soakaway point of each drainage
catchment, and any culverts passing under the
carriageway, to facilitate management of pollution
and flooding risk.
Remote survey
The survey of drainage systems by means that
preclude man-entry into the drainage assets.
Rodding camera
A CCTV camera that is moved along the pipework
using flexible rods.
NOTE: Such cameras are generally used to
access 150mm or smaller diameter pipes,
particularly those with bends.
9
CS 551 Revision 0
Terms and definitions
Terms (continued)
Term
Definition
Service condition
The performance of an asset and severity of the
defects that affect its serviceability, independent of
its structural condition.
NOTE: Service defects are addressed by
maintenance of the asset such as cleansing or
vegetation clearance.
Set-up
The process of setting up the equipment at one
chamber or other node type, for survey of the
chamber and connected pipes in one or more
directions.
Site
The location or locations of the survey or surveys
that constitute the works.
Structural condition
The condition of the fabric of the asset and the
severity of defects that affect its integrity.
NOTE: Structural defects are addressed by
repairing or replacing the asset.
Validation survey
A survey to verify whether the inventory
information held on the DDMS, previously derived
from drawings, is a true record of the visible
surface point assets or not.
10
CS 551 Revision 0
1.
1. Scope
Scope
Aspects covered
1.1
Highway drainage surveys shall be undertaken in accordance with the requirements stated in this
document.
NOTE
This document covers general requirements, survey equipment and procedures, quality control and
reporting requirements for validation survey, priority asset survey, filter drain condition survey by GPR,
all assets condition and connectivity survey, pipework and chambers defect survey by CCTV and
pipework geometric survey by laser profiler.
Implementation
1.2
This document shall be implemented forthwith on all schemes involving the survey of highway drainage
assets on the Overseeing Organisations' motorway and all-purpose trunk roads according to the
implementation requirements of GG 101 [Ref 3.N].
Use of GG 101
1.3
The requirements contained in GG 101 [Ref 3.N] shall be followed in respect of activities covered by
this document.
Health and safety
1.4
A pre-survey risk assessment and health and safety plan shall be prepared in accordance with MHSC
2015 [Ref 4.N] making reference to any known hazards associated with the drainage system identified
in the pre-construction information.
NOTE
The pre-construction information is referenced in the schedule of requirements.
1.5
Any chamber, pipework or culvert forming part of a highway drainage system must be classified as a
confined space in respect of personnel entry in accordance with SI 1713 [Ref 2.N].
NOTE
A confined space is defined in the regulations as any place in which by virtue of its enclosed nature
there arises a foreseeable risk such as asphyxiation from gas, lack of oxygen or a build-up of fumes
due to the operations being undertaken, loss of consciousness due to increased body heat, drowning,
or serious injury from fire or explosion due to an explosive atmosphere.
1.6
Person entry to the drainage system shall be avoided where remote access survey methods can be
employed.
NOTE
The Confined Spaces Regulations SI 1713 [Ref 2.N] require that no person enters a confined space to
carry out work for any purpose unless it is not reasonably practicable to achieve that purpose without
such entry.
1.7
All electrical equipment to be used in potentially explosive atmospheres must be in accordance with
EPSIUPEAR [Ref 8.N].
NOTE
All highway drainage systems are to be classified as zone 2 for the use of electrical equipment in
potentially explosive atmospheres, in accordance with DSEAR S.I. No. 2776 [Ref 2.I] unless stated
otherwise in the schedule of requirements.
1.8
Gas detectors shall be used in all confined spaces.
1.9
The drainage survey team shall be able to maintain immediate two-way contact with the Overseeing
Organisation's representative for the duration of the survey.
1.10
Where an access chamber cover or gully grating or other asset is damaged during the drainage survey,
or found to have been previously damaged or broken, the survey team shall:
1) provide temporary protection to the asset;
2) notify the Overseeing Organisation's representative immediately;
11
CS 551 Revision 0
1. Scope
3) remain on site until the Overseeing Organisation's representative is in attendance;
4) ensure that the traffic management is not removed.
12
CS 551 Revision 0
2.
2. General requirements
General requirements
Scope of works
2.1
The drainage survey shall be carried out as detailed in the schedule of requirements.
NOTE
An example schedule of requirements is given in Appendix A.
2.2
Where the specific requirements are not stated in the provided schedule of requirements or a schedule
of requirements has not been provided, then the default options stated in the example schedule of
requirements given in Appendix A shall apply.
2.2.1
The drainage survey method should be one or more of the following as defined in this document:
1) validation survey;
2) priority asset survey;
3) filter drain condition survey by GPR;
4) all assets condition and connectivity survey;
5) pipework and chambers defect survey by CCTV;
6) pipework geometric survey by laser profiler.
2.3
The location of the drainage survey shall be as detailed in the schedule of requirements.
2.4
The drainage survey shall be planned and carried out in accordance with any constraints detailed in the
schedule of requirements, including:
1) restrictions on access routes to the whole site, or sections of the site;
2) restrictions on the days or hours of working;
3) restrictions on the overall programme or sequencing of the works;
4) restrictions imposed by traffic management arrangements;
5) restrictions due to other works within the area;
6) restrictions due to environmental or ecological constraints.
2.5
The drainage survey shall be measured in accordance with MCHW Volume 5 Series 9000 [Ref 5.N]
and any specific method of measurement provided for the works.
Traffic management
2.6
Traffic management shall be provided as detailed in the schedule of requirements, either:
1) by others arranged by the area management team; or
2) by others arranged by the Overseeing Organisation's representative; or
3) arranged by the drainage survey team.
13
CS 551 Revision 0
3.
3. Validation survey
Validation survey
Survey requirements
Scope of survey
3.1
A validation survey shall be carried out to verify whether the inventory information held on the drainage
data management system (DDMS), previously derived from drawings, is a true record of the visible
surface point assets or not.
3.2
A validation survey shall include the following (unless detailed otherwise in the schedule of
requirements):
1) a walkover survey to verify surface visible point assets only;
2) determination of whether the recorded location and asset type of the surface visible point assets is
correct or not;
3) submission of digital data in the format defined by the Overseeing Organisations in the NAAs to CD
535 [Ref 1.N]
NOTE 1
A validation survey is:
1) a quick walkover survey;
2) used to assess drainage data that has been derived from drawings, not previous field surveys;
3) carried out in the daytime;
4) only carried out where it is safe to access the verge, hard shoulder or footpath without lane closures,
unless sharing other traffic management arrangements.
NOTE 2
A validated survey does not:
1) primarily record previously unrecorded inventory, although any such point assets found during the
course of the survey are to be captured;
2) record asset condition;
3) require any prior vegetation clearance.
Survey data round-tripping
3.3
The drainage inventory information on the DDMS in the catchment(s) to be surveyed shall be
round-tripped in accordance with the specific procedures and formats detailed by the Overseeing
Organisations in the NAAs to CD 535 [Ref 1.N] by:
1) downloading the available information;
2) updating the inventory status of the surface visible point assets in the field;
3) retaining as part of the data, without change, any inventory and condition information on any
non-surveyed assets; and
4) submission for uploading of this information to the DDMS.
3.4
Where the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] require additional activities to
complete the round-tripping of drainage information to the DDMS these shall be carried out as part of
the survey.
Survey equipment
3.5
The validation survey shall be recorded on a handheld computer equipped with:
1) a mobile geographic information system (GIS);
2) an in-built or connected global positioning system (GPS) receiver capable of recording locational
position to the accuracy stated in CD 535 [Ref 1.N] for inventory survey; and
14
CS 551 Revision 0
3. Validation survey
3) the ability to take digital photographs or to link to photographs taken by a digital camera.
3.5.1
The mobile GIS should be pre-loaded with the following data sets prior to the survey (where available):
1) the downloaded DDMS drainage system data;
2) detailed topographic mapping for the site;
3) high resolution aerial photography for the site;
4) marker post locations for the site.
Method of survey
3.6
The location of each surface visible point asset in the DDMS data shall be identified in the field using a
combination of the GPS, the detailed mapping, the marker posts and/or the aerial photography.
3.7
The inventory status of each surface visible "unvalidated" point asset in the DDMS data shall be
changed to one of the following:
1) "confirmed" where the location of the asset is correct to within ±5m tolerance, and the asset type is
correct;
2) "modified" where the location of the asset is correct to within ±5m tolerance, but the asset type is
incorrect;
3) "unproven" where there is no corresponding point asset within ±5m of the location shown on the
map.
3.7.1
Chambers should be "confirmed" without lifting the covers to determine the chamber type.
3.7.2
Where the status is "modified" the asset type should be determined in accordance with CD 535 [Ref
1.N].
3.7.3
Point assets in the carriageway or central reserve should be checked remotely from the side of the road
or from the nearest overbridge, their location "eyed-in" against the aerial photography and marked as
"confirmed" where it is judged to be correct.
3.7.4
Any point assets that can not be checked because the location is not accessible, is hidden, or is
otherwise not included in the survey should retain their default status of "unvalidated".
3.7.5
Although the validation survey concentrates on the surface visible point assets, the surface visible
continuous assets should also be observed, as an understanding of the system connectivity will greatly
aid the identification and checking of the point assets.
3.8
Digital photographs shall be taken of any safety related defects that are identified in the survey.
3.9
Where a point asset is encountered during the validation survey that is not in the DDMS data (to within
a tolerance of ±5m) it shall be added as a "new" asset, recording the following details:
1) the location of the asset to the accuracy stated in CD 535 [Ref 1.N] for inventory survey and to the
national survey grid stated by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N];
2) the asset type in accordance with CD 535 [Ref 1.N];
3) any relevant remarks.
3.9.1
Where a chamber is found that is not in the DDMS data, that is part of the drainage system being
surveyed, it should be recorded as a manhole, unless there is reasonable evidence to indicate
otherwise.
3.9.2
When "new" point assets are added there should be no attempt to join them with any other assets, new
or existing.
3.9.3
Where a point asset is found to be more than 5m from its recorded location, this should be recorded as
follows:
1) the original asset in the DDMS data is changed to "unproven";
15
CS 551 Revision 0
3. Validation survey
2) the asset as found in the field is recorded as "new" at the new location.
Termination of survey
3.10
The validation survey shall be terminated when either:
1) all of the accessible surface visible point assets in the DDMS data have been checked; or
2) the first 20% of the surface visible point assets in the DDMS data have been checked and all found
to be "confirmed" and spot checking of a further 20% are also all found to be "confirmed"; or
3) the first 20% of the surface visible point assets in the DDMS data have been checked and all found
to be "unproven" and spot checking of a further 20% are also all found to be "unproven".
NOTE
It is not necessary to survey all of the surface visible point assets in the DDMS data where they are
either all "confirmed" or all "unproven".
3.10.1
Where the status of the surveyed surface visible point assets in the DDMS data is mixed, all of the
accessible assets should be surveyed.
Quality control requirements
Surveyor competency
3.11
The senior surveyor shall have at least five years experience of surveying highway drainage systems.
Survey method quality control
3.12
At the start of each survey the alignment between the GIS mapping, aerial photography and GPS
location shall be checked to be within +/-5m at a clearly identifiable feature on the mapping and aerial
photography.
3.12.1
Where the data sets do not align to within acceptable tolerance, further checks should be carried out to
determine the source of the problem and the matter rectified before proceeding with the survey.
3.13
The validation survey procedure shall maintain the DDMS data file format in accordance with the
requirements of the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N], during updating in the
GIS.
Reporting requirements
Data submission
3.14
Unless detailed otherwise in the schedule of requirements, the survey report shall consist of a
submission for upload to the DDMS of the following digital data:
1) the round-tripped DDMS survey data, including any original unchanged data, as well as new and
changed data, as separate files for each catchment;
2) any digital photographs taken during the survey referenced to the asset data in accordance with the
requirements of the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
Survey data
3.15
All survey data shall be reported using the standard coding system and nomenclature defined by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
3.16
All recorded survey data shall be submitted for upload to the DDMS in the standard digital format(s)
defined by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
3.17
All round-tripped existing drainage data from the DDMS shall retain the unique reference of each asset.
3.18
Where "new" assets are added to the data during the survey they shall be assigned a field reference
that is unique within the survey.
16
CS 551 Revision 0
NOTE
3. Validation survey
A permanent unique asset reference is automatically assigned by the DDMS when the data is
uploaded.
Photographs
3.19
All photographs shall be:
1) in colour;
2) in JPEG format as .JPG files;
3) submitted for upload to the DDMS as documents attached to the asset to which they relate;
4) at a resolution of at least 1.0 megapixels.
17
CS 551 Revision 0
4.
4. Priority asset survey
Priority asset survey
Survey requirements
Scope of survey
4.1
A priority asset survey shall be carried out in areas where the highway drainage system is unknown or
uncertain, in order to locate the outfall or soakaway point of each drainage catchment, and any culverts
passing under the carriageway, to facilitate management of pollution and flooding risk.
4.2
A priority asset survey shall include the following (unless detailed otherwise in the schedule of
requirements):
1) a desk study to identify potential priority asset locations for field study;
2) a walkover survey of the targeted locations;
3) recording of the location, inventory and asset level condition of each identified priority asset;
4) submission of digital data in the format defined by the Overseeing Organisations in the NAAs to CD
535 [Ref 1.N].
NOTE 1
A priority asset survey is:
1) carried out where there is little or no drainage inventory on the DDMS;
2) a "quick win" to expedite the acquisition of knowledge of the key drainage assets that can present a
risk of either pollution (outfalls and soakaways) or flooding (culverts);
3) a combination of a desk study and a walkover survey;
4) carried out in the daytime;
5) carried out only where it is safe to access the verge, footpath, adjacent earthworks or adjacent land
without lane closures, unless sharing other traffic management arrangements.
NOTE 2
A priority asset survey does not:
1) record the drainage assets that the priority assets connect to;
2) require any prior vegetation clearance.
Survey data round-tripping
4.3
Survey data shall be round-tripped from the DDMS where available.
4.4
Where there is some drainage inventory information in the catchment(s) to be surveyed on the DDMS,
the survey shall round-trip this data in accordance with the specific procedures and formats detailed by
the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] by:
1) downloading the available information;
2) confirming or updating the inventory and condition of the priority assets in the field;
3) retaining as part of the data, without change, any inventory and condition information on any
non-surveyed assets; and
4) submission for uploading of this information to the DDMS.
4.5
Where there is no existing drainage inventory information in the catchment(s) to be surveyed on the
DDMS, the survey shall consist of the following:
1) a first time survey of the inventory and condition of the priority drainage assets only;
2) the submission for upload of this information to the DDMS in accordance with specific procedures
and formats detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
4.6
Where the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] require additional activities to
complete the round-tripping of drainage information to the DDMS these shall be carried out as part of
the survey.
18
CS 551 Revision 0
4. Priority asset survey
Desk study
4.7
Available data sets relevant to the identification of potential priority drainage asset locations shall be
collated.
NOTE
The following data sets can be used where available for identifying potential priority drainage asset
locations:
1) existing drainage asset information including:
a) any existing drainage data on the DDMS;
b) any drainage, pavement, earthworks or general layout as-built drawings that show drainage
assets;
c) any locally available drainage asset survey data;
d) any drainage asset maintenance data;
e) any environmental or soft estate data that records drainage assets;
f) any structures data that records culverts;
2) existing topographic data that can help to identify the fall of the land, low points in the highway
network and water courses, including:
a)
b)
c)
d)
e)
f)
g)
h)
national survey detailed topographic mapping;
detailed aerial photography;
high resolution light detection and ranging (LiDAR) survey data;
high resolution digital terrain models;
data on the highway gradient and falls;
any locally available survey data;
any modelling carried out to identify highway drainage catchments;
national detailed river network mapping;
3) other existing relevant data that can assist the desk study including:
a) local knowledge of inspectors, engineers and maintenance staff who have worked on the
network for a long time;
b) the record of historic flood events;
c) the record of flooding hotspots;
d) national flood hazard mapping;
e) mapping of the highway land ownership boundary;
f) previous local studies that can contain a drainage element on topics such as: flood mitigation,
pollution control measures, environmental impact.
4.8
A desk study shall be carried out by compiling the various relevant data sets into a GIS to identify
potential priority drainage asset locations for investigation in the field.
NOTE
The following steps could be undertaken to help identify potential priority drainage asset locations and
prepare for the field survey:
1) locate all known priority drainage assets in the GIS, identify the source(s) of each data point, and
hence the confidence in their location;
2) use any available drainage and topographic information to identify drainage catchments and likely
flow directions, and hence target the general area of potential priority drainage assets;
3) use the topographic data, aerial photography, flooding data and culvert information to identify low
points in the road network, and the surrounding ground, with adjacent or crossing water courses,
and mark these areas as targets for field inspection;
4) inspect the aerial photography for small ponds adjacent to the carriageway which can be soakaway
infiltration basins;
5) where high resolution aerial photography is available, inspect this in association with the identified
low points in the road network and water courses to see whether outfall or culvert structures can be
identified;
19
CS 551 Revision 0
4. Priority asset survey
6) review the resultant map of known priority drainage assets and target locations, and identify gaps
where possible drainage catchments are missing priority drainage assets or target locations;
7) refer back to the aerial photography, maps and topographic data, and identify additional targets for
field inspection in the areas of the gaps;
8) identify from the topographic mapping and aerial photography appropriate access routes to the
areas requiring field inspection;
9) consult the available land ownership information to determine whether the field survey is likely to
require access to third party land, and seek permissions where required;
10) prepare a field inspection programme.
Survey equipment
4.9
The priority asset shall be recorded on a handheld computer equipped with:
1) a mobile GIS;
2) an in-built or connected GPS receiver capable of recording locational position to the accuracy stated
in CD 535 [Ref 1.N] for inventory survey; and
3) the ability to take digital photographs or to link to photographs taken by a digital camera.
4.9.1
The mobile GIS should be pre-loaded with the following data sets prior to the priority asset survey
(where available):
1) the downloaded DDMS drainage system data (if any);
2) the desk study GIS mapping, aerial photography and other data sets;
3) the known priority drainage assets, the target locations and the identified access routes.
4.9.2
The following equipment may be useful for the field survey:
1) a metal detector for finding buried soakaway chamber covers;
2) an appropriate means for opening and lifting chamber covers for identifying soakaways or for
determining flow direction to outfalls, depending on the local health and safety requirements.
Method of survey
4.10
At each inspection area the priority drainage asset shall be located or confirmed as absent with the
validation status being recorded as either:
1) "confirmed" where the location of the asset downloaded from the DDMS is correct to within ±5m
tolerance and the inventory details are all correct; or
2) "modified" where the location and/or the inventory details downloaded from the DDMS have been
updated; or
3) "new" where a previously unrecorded asset has been found; or
4) "unvalidated" where a priority asset is suspected but not positively proven and requires further
investigation such as:
a) a chamber has been found but the cover could not be lifted to confirm that it is a soakaway; or
b) an outfall to a sewer is suspected.
4.10.1
Where no asset was found at the location downloaded from the DDMS, the asset should be deleted.
4.11
All mandatory data fields for asset inventory and survey parameters shall be recorded using the
procedures detailed in CD 535 [Ref 1.N] and the codes and formats detailed by the Overseeing
Organisations in the NAAs to CD 535 [Ref 1.N].
4.12
Where optional data fields for asset inventory and survey parameters are recorded, the codes and
formats detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] shall be used.
20
CS 551 Revision 0
4. Priority asset survey
4.12.1
Soakaway chamber inspections may include the lifting of manhole covers to confirm the type of
soakaway structure where local health and safety procedures permit.
4.12.2
There should be no internal investigation of soakaway chambers, culverts or other confined spaces.
4.13
The overall asset level service and structural condition of the priority asset shall be assessed in
accordance with the drainage condition grade quick assessment procedure given in Appendix B, so far
as this is possible given any health and safety constraints.
4.14
Any significant defects in either the service or structural condition shall be recorded and photographed,
although full defect recording is not required.
4.15
Digital photographs shall be taken of every priority drainage asset to illustrate the type, location and
condition of each asset.
Quality control requirements
Surveyor competency
4.16
The senior surveyor shall have at least five years experience of surveying highway drainage systems.
Survey method quality control
4.17
The priority asset survey results shall be reviewed in the field at least daily to identify any gaps.
NOTE
Where gaps are apparent in the priority asset survey results, the following can be assessed:
1) where no outfall structure has been found, could the outfall be at the ownership boundary and
without a structure?;
2) is the flow passing under the carriageway so small that it can be carried by a small diameter pipe
rather than a culvert?;
3) is the structure carrying the flow under the carriageway more correctly recorded as a bridge rather
than a culvert?;
4) could the outfall or soakaway be further away from the highway?;
5) could the outfall or soakaway be on the other side of the road?;
6) could the outfall be on the other side of the water course?;
7) could there be a buried soakaway chamber cover that can be identified by a metal detector?;
8) is a manhole actually a soakaway chamber that can be confirmed by lifting the cover?;
9) could there be a buried infiltration trench?;
10) could a nearby pond actually be an infiltration basin?;
11) could the drainage discharge to a foul sewer?;
12) has there been confusion in the nomenclature of outfall, outlet and inlet?
Reporting requirements
Data submission
4.18
Unless detailed otherwise in the schedule of requirements, the survey report shall consist of a
submission for upload to the DDMS of the following digital data:
1) the round-tripped DDMS survey data (if any) combined with the new survey data as separate files
for each catchment;
2) any digital photographs taken during the survey referenced to the asset data in accordance with the
requirements of the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
Survey data
4.19
All survey data shall be reported using the standard coding system and nomenclature defined by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
21
CS 551 Revision 0
4. Priority asset survey
4.20
All recorded survey data shall be submitted for upload to the DDMS in the standard digital format(s)
defined by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
4.21
Any round-tripped existing drainage data from the DDMS shall retain the unique reference of each
asset.
4.22
"New" assets added to the data during the survey shall be assigned a field reference that is unique
within the survey.
NOTE
A permanent unique asset reference is automatically assigned by the DDMS when the data is
uploaded.
Photographs
4.23
All photographs shall be:
1) in colour;
2) in JPEG format as .JPG files;
3) submitted for upload to the DDMS as documents attached to the asset to which they relate;
4) at a resolution of at least 1.0 megapixels.
22
CS 551 Revision 0
5.
5. Filter drain condition survey by GPR
Filter drain condition survey by GPR
Survey requirements
Scope of survey
5.1
A filter drain condition survey shall be carried out to determine the service condition due to sediment
contamination of the filter medium of combined surface and sub-surface drains, and other forms of filter
drain, including the use of ground penetrating radar (GPR).
5.2
A filter drain condition survey by GPR shall include the following (unless detailed otherwise in the
schedule of requirements):
1) details of the location, date, equipment and personnel of the survey;
2) GPR survey of the required filter drains;
3) survey of the location and type of all associated nodes at each end of each filter drain to the
accuracy stated in CD 535 [Ref 1.N] for condition survey and to the national survey grid stated by
the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N];
4) interpretation and recording of the variation in void ratio of the filter medium along the length of the
filter drain as an indication of the degree to which the filter medium has become contaminated with
sediment;
5) recording of the overall asset level service and structural condition grades of the filter medium;
6) preparation of a report on recommended remedial works or further investigations;
7) submission of a digital report and digital data sets in the formats defined by the Overseeing
Organisations in the NAAs to CD 535 [Ref 1.N].
NOTE
A filter drain condition survey by GPR is;
1) a field survey along the surface centre line of a filter drain;
2) carried out using a vehicle mounted GPR;
3) carried out either remote from the carriageway or at the edge of the carriageway and could require
traffic management.
Survey data round-tripping
5.3
Survey data shall be round-tripped from the DDMS where available.
5.4
Where there is some drainage inventory information in the catchment(s) to be surveyed on the DDMS,
the survey shall round-trip this data in accordance with specific procedures and formats detailed by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] by:
1) downloading the available information;
2) confirming or updating the inventory, condition and defects of the filter drain medium and the
inventory of the associated nodes in the field;
3) retaining as part of the data, without change, any inventory and condition information on any
non-surveyed assets; and
4) submission for uploading of this information to the DDMS.
5.5
Where there is no drainage inventory information in the catchment(s) to be surveyed on the DDMS the
survey shall consist of:
1) a first time survey of the inventory, condition and defects of the filter drain medium and the inventory
of the associated nodes;
2) the submission for upload of this information to the DDMS in accordance with specific procedures
and formats detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
23
CS 551 Revision 0
5.6
5. Filter drain condition survey by GPR
Where the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] require additional activities to
complete the round-tripping of drainage information to the DDMS these shall also be carried out as part
of the survey.
Survey equipment
5.7
The filter drain condition survey equipment shall be checked prior to each shift in accordance with the
quality control procedures detailed in Section 5, to ensure that it is maintained in full working order.
5.8
The radar penetration shall be effective to a depth of at least 750mm.
5.9
The location of the radar antenna shall be continuously recorded by GPS capable of recording
locational position to the accuracy stated in CD 535 [Ref 1.N] for condition survey, either mounted
above the centre of the antenna, or in such a way that the location of the centre of the antenna can be
determined.
Method of survey
5.10
An inspection of the site shall be carried out in advance of the filter drain condition survey to determine
where there are any barriers or other obstructions that would make a vehicle mounted GPR survey
impractical.
5.11
The radar survey shall be carried out progressing at a speed to optimise the recorded data in
accordance with the equipment calibration.
5.12
The radar antenna shall be positioned at a constant height relative to the surface of the filter drain.
NOTE
Undulations in the surface of the filter drain can make it impractical for the antenna to ride along the top
of the drain.
5.12.1
Filter drains located at the edge of the carriageway may be surveyed by an antenna mounted to the
side of a vehicle such that the antenna is positioned at a constant height relative to the carriageway and
can be accurately positioned and transported along the line of the filter drain.
5.12.2
Filter drains located remote from the carriageway may be surveyed by an antenna mounted to the front
or rear of an all terrain vehicle that can straddle the filter drain.
5.13
The filter drain condition survey shall measure and report the service condition of the filter medium
along the centre line.
NOTE
Results from other survey paths can be affected by fines clogging the filter medium at the edge of the
drain.
5.14
The radar gain shall be set to optimise the recorded data in accordance with the equipment calibration.
5.15
The location and type of all associated nodes shall be surveyed at each end of each filter drain to the
accuracy stated in CD 535 [Ref 1.N] for condition survey and to the national survey grid stated by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
5.15.1
The nodes at each end of a filter drain may be either:
1) a chamber; or
2) a ghost node at the start of the filter drain where there is no physical point asset; or
3) a ghost node at the junction with another filter drain where there is no physical point asset; or
4) a phantom node where the survey is abandoned before the end of the filter drain and the
continuation of the filter drain is not visible.
Interruption of survey
5.16
Where movement off-line is necessitated by a barrier or street furniture, the antenna shall be
re-positioned over the centre of the drain once the obstacle has been passed.
24
CS 551 Revision 0
5.17
5. Filter drain condition survey by GPR
Where a survey run is interrupted by an obstruction the survey shall record the following using the
codes defined by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N]:
1) the start and end positions of the gap in the survey;
2) the nature of the obstruction.
Abandonment of survey
5.18
A survey run of a filter drain shall be abandoned for any of the following reasons:
1) the filter drain could not be found at all;
2) the continuation of the filter drain could not be found;
3) a continuous obstruction prevents further access;
4) a situation has occurred that places the survey equipment, the survey personnel, the drainage asset
or the road users at risk.
5.19
Where a filter drain condition survey run is abandoned then the following shall be carried out:
1) recording of the situation on the survey record;
2) photograph the issue;
3) recording of the appropriate code for the unsurveyed length of filter drain in accordance with the
requirements of the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N];
4) recording of the appropriate node type and location as one of the following:
a) where the filter drain could be found but not accessed a ghost node or chamber is recorded at
the end of the unsurveyed filter drain;
b) where the continuation of the filter drain could not be found a phantom node is recorded at the
end of the surveyed section;
c) where a filter drain could not be found at all the existing DDMS record (where there is one) is
deleted from the data.
Quality control requirements
Surveyor competency
5.20
Evidence shall be provided that the surveyor undertaking the GPR survey has received training in the
execution and interpretation of GPR surveys.
Survey method quality control
5.21
Prior to the commencement of works a quality control procedure shall be submitted detailing:
1) the procedure for ensuring consistency of product;
2) how quality of product will be monitored during the works;
3) the equipment calibration method;
4) the results of the calibration carried out immediately prior to the works;
5) certification for the radar confirming that it is not susceptible to outside interference; and
6) the method of interpretation of the void ratio.
5.22
The equipment calibration shall be provided as a chart detailing the relationship between image colour
on the output results and filter medium void ratio.
5.22.1
The calibration chart should be similar to the example given in Fig 5.22.1.
25
CS 551 Revision 0
5. Filter drain condition survey by GPR
Figure 5.22.1 GPR example calibration chart
Reporting requirements
Data submission
5.23
Unless detailed otherwise in the schedule of requirements, the survey report shall consist of a
submission for upload to the DDMS of the following digital data:
1) a survey report in PDF format as detailed in the report requirements;
2) the round-tripped DDMS survey data (if any) combined with the new survey data as separate files
for each catchment;
3) any digital photographs taken during the survey.
Report
5.24
A report shall be provided in PDF format presenting the following:
1) a graphical output of the filter drain condition survey trace provided to scale as a digital image for
each length of filter drain surveyed showing the following:
a) the unique asset reference of the filter drain;
b) the unique references of the nodes at each end of the filter drain, whether they are physical
assets or not;
c) distance along the filter drain in metres from the upstream end;
d) a vertical trace of the survey results colour coded in accordance with the equipment calibration;
e) vertical distance down the trace with a scale in 0.1m increments;
2) an interpretation of each survey trace dividing the trace longitudinally into zones of interpreted void
ratio carried out in accordance with Table 5.24.1;
3) overall service and structural condition grades for each filter drain determined;
4) a summary of those sections of filter drain with an interpreted overall poor void ratio or standing
water;
5) recommendations for the location and nature of any remedial works or further investigations.
NOTE
Two graphical traces can be provided for each filter drain to achieve optimum results, one for the upper
level to approximately 300mm depth and the second for the lower level to the carrier pipe, or to the
base of the filter drain where there is no carrier pipe.
26
CS 551 Revision 0
5.24.1
5. Filter drain condition survey by GPR
The condition survey and the resultant recommendations should be consistent with the examples given
in Table 5.24.1.
27
Interpreted void ratio
Good void ratio.
Adequate void ratio.
Poor void ratio.
Standing water.
Interpretation
Filter medium with a
higher void ratio in line
with type B grading
suggesting good
performance.
Filter medium has a
locally reducing
permeability suggesting
adequate performance.
Filter medium with a
lower void ratio and
probable sediment
contamination or filter
medium outside the type
B grading criteria (such
as type A or C grading)
suggesting poor
performance.
Indicates moisture
present. Where present
outside a period of
precipitation this can
indicate a blockage in
the carrier pipe or
standing water in the
filter drain due to an
underlying problem that
can adversely affect the
pavement construction
and/or earthwork
performance.
GPR survey trace
colour (adopting
colour scheme of
example GPR
calibration)
Predominantly green or
yellow.
Predominantly orange
with isolated patches of
reds.
Predominantly reds.
Predominantly blue.
Table 5.24.1 GPR example interpretation and recommendations
Service condition (void
ratio) defect codes as
defined by the
Overseeing
Organisations in the
NAAs to CD 535 [Ref
1.N]
Service condition
(void ratio) defect
codes
Service condition defect
scores as defined by the
Overseeing
Organisations in the
NAAs to CD 535 [Ref
1.N]
Service condition
defect scores
28
Further investigation
required.
Replace or recycle the
filter medium aggregate
where in excess of 20m
length of filter drain
affected. Reassess void
ratio after remedial
works.
Remedial works
probably not necessary
at present. Monitor
situation.
No further action
required.
Recommendation
CS 551 Revision 0
5. Filter drain condition survey by GPR
CS 551 Revision 0
NOTE
5. Filter drain condition survey by GPR
The zone of worst interpreted void ratio determines the overall service condition grade for the filter
drain as follows:
1) where the whole filter drain has a good interpreted void ratio the service condition is grade 1;
2) where any part of the filter drain has an adequate interpreted void ratio, and there is no poor void
ratio and no areas of standing water, the service condition is grade 3;
3) where any part of the filter drain has a poor interpreted void ratio the service condition is grade 5;
4) where any part of the filter drain is interpreted as having standing water the service condition is
grade 5.
5.25
The PDF report shall be submitted for upload to the DDMS as defined by the Overseeing Organisations
in the NAAs to CD 535 [Ref 1.N].
Survey data
5.26
All survey data shall be reported using the standard coding system and nomenclature defined by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
5.27
All coding shall be directly entered into a computer or handheld device that restricts entries to valid
codes.
5.28
Where the survey is round-tripping existing drainage data from the DDMS the unique reference of each
asset shall be retained in the round-tripped data.
5.29
Where new assets are added to the data during the survey they shall be assigned a field reference that
is unique within the survey.
NOTE
A permanent unique asset reference is automatically assigned by the DDMS when the data is
uploaded.
5.30
At the commencement of the survey of every length of filter drain between consecutive access points,
the surveyor shall complete new header information in accordance with the requirements of the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
5.31
Every filter drain shall be divided longitudinally into zones of the same interpreted void ratio in
accordance with Table 5.24.1, recording the following:
1) distance along the filter drain from the upstream end to the start and end of each discrete zone of
interpreted void ratio;
2) the interpreted service condition (void ratio) defect code for the discrete zone, in accordance with
the requirements of the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N];
3) the service condition defect code for any unsurveyed lengths, in accordance with the requirements
of the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
5.31.1
Where more than one survey trace is obtained for a filter drain the void ratio zones should be interpreted
from an aggregate of all the available survey data but disregarding any unrepresentative data.
5.32
The overall asset level structural condition grade of the filter drain shall be assessed in accordance with
the drainage condition grade quick assessment procedure given in Appendix B and reported using the
structural condition defect codes in accordance with the requirements of the Overseeing Organisations
in the NAAs to CD 535 [Ref 1.N].
5.33
Each of the interpreted service condition (void ratio) defect codes and structural condition defect codes
shall be scored in accordance with the scoring system detailed by the Overseeing Organisations in the
NAAs to CD 535 [Ref 1.N].
5.33.1
Automated condition scoring should be carried out by the recording software or by the DDMS during
data upload.
5.34
The overall asset level service condition grade shall be derived by aggregating the scores for each
recorded defect code in accordance with the aggregating procedure detailed in CD 535 [Ref 1.N] for
continuous assets.
29
CS 551 Revision 0
5. Filter drain condition survey by GPR
5.34.1
Automated asset level condition grading should be carried out by the recording software or by the
DDMS during data upload.
NOTE
In most cases the adoption of this aggregating procedure results in the zone of worst interpreted void
ratio determining the overall service condition grade.
5.35
All recorded survey data shall be submitted for upload to the DDMS in the standard digital format(s)
defined by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
Photographs
5.36
All photographs shall be:
1) in colour;
2) in JPEG format as .JPG files;
3) submitted for upload to the DDMS as documents attached to the asset to which they relate;
4) at a resolution of at least 1.0 megapixels.
30
CS 551 Revision 0
6.
6. All assets condition and connectivity survey
All assets condition and connectivity survey
Survey requirements
Scope of survey
6.1
An all assets condition and connectivity survey shall be carried out to determine the inventory, asset
level condition and connectivity of all drainage assets in a drainage system.
6.2
An all assets condition and connectivity survey shall include the following (unless detailed otherwise in
the schedule of requirements):
1) desk study of available drainage information and aerial photography;
2) details of the location, date, equipment and personnel of the survey;
3) survey of all drainage assets forming the drainage system consisting of:
a) visual inspection of the surface drainage assets;
b) lifting manhole covers and gratings and inspecting the chamber and pipework using a pole
mounted camera;
c) assumptions on below ground pipework and inaccessible assets that could not be inspected;
4) identification of the asset type of all surveyed assets in accordance with the classification system
detailed in CD 535 [Ref 1.N];
5) survey of the location of all assets to the accuracy stated in CD 535 [Ref 1.N] for condition survey
and to the national survey grid stated by the Overseeing Organisations in the NAAs to CD 535 [Ref
1.N];
6) recording of all the mandatory data fields for asset inventory and survey parameters using the codes
detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] for all assets surveyed;
7) recording of the optional data fields for asset inventory and survey parameters using the codes
detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] for all assets surveyed as
far as safe access permits;
8) recording of the overall asset level structural and service condition grade for all assets surveyed
using the drainage condition grade quick assessment procedure given in Appendix B;
9) recording of the connectivity and flow direction for every continuous drainage asset using the codes
detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N];
10) recording of the level of certainty/uncertainty in the survey data using the codes detailed by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N];
11) taking of still photographs showing the typical nature of the assets surveyed;
12) submission of digital data in the format defined by the Overseeing Organisations in the NAAs to CD
535 [Ref 1.N].
NOTE 1
An all assets condition and connectivity survey is:
1) a combination of a desk study and a quick walkover survey;
2) carried out with internal examination of the below ground assets at accessible chambers only;
3) carried out in the daytime;
4) carried out only where it is safe to access the verge, hard shoulder, footpath, adjacent earthworks or
adjacent land without lane closures, unless sharing other traffic management arrangements.
NOTE 2
An all assets condition and connectivity survey does not:
1) capture detailed defect level condition of the assets, although where safety critical defects are found
these are recorded;
2) require any prior vegetation clearance.
31
CS 551 Revision 0
6. All assets condition and connectivity survey
Survey data round-tripping
6.3
Survey data shall be round-tripped from the DDMS where available.
6.4
Where there is some drainage inventory information in the catchment(s) to be surveyed on the DDMS
the survey shall round-trip this data in accordance with specific procedures and formats detailed by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] by:
1) downloading the available information;
2) confirming or updating the inventory, condition and connectivity of all the drainage assets that
constitute the drainage system;
3) retaining as part of the data, without change, any inventory and condition information on any
non-surveyed assets; and
4) the submission for uploading of this information to the DDMS.
6.5
Where there is no drainage inventory information in the catchment(s) to be surveyed on the DDMS the
survey shall consist of the following:
1) a first time survey of the inventory, condition and connectivity of all the drainage assets that
constitute the drainage system;
2) the submission for upload of this information to the DDMS in accordance with specific procedures
and formats detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
6.6
Where the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] require additional activities to
complete the round-tripping of drainage information to the DDMS these shall be carried out as part of
the survey.
Desk study
6.7
Available data sets relevant to identification of drainage assets shall be collated.
NOTE
The data sets listed for priority asset surveys, where available, can be used for identifying drainage
asset locations.
6.8
A desk study shall be carried out by compiling the various relevant data sets into a GIS to identify
drainage asset locations for investigation in the field.
NOTE
The steps listed for priority asset surveys can be used to help identify drainage asset locations and
prepare for the field survey.
Survey equipment
6.9
The all assets condition and connectivity survey shall be recorded on a handheld computer equipped
with:
1) a mobile GIS;
2) an in-built or connected GPS receiver capable of recording locational position to the accuracy stated
in CD 535 [Ref 1.N] for condition survey;
3) a connected laser rangefinder with digital compass, or some other means, to remotely locate
inaccessible assets in the carriageway or central reserve; and
4) the ability to take digital photographs or to link to photographs taken by a digital camera.
6.9.1
The mobile GIS should be pre-loaded with the following data sets prior to the all assets condition and
connectivity survey (where available):
1) the downloaded DDMS drainage system data (if any);
2) the desk study GIS mapping, aerial photography and other data sets;
3) the drainage assets identified in the desk study and access routes.
32
CS 551 Revision 0
6. All assets condition and connectivity survey
6.10
A pole mounted camera with appropriate recording hardware and software shall be used for the
inspection of chambers and pipework.
6.10.1
The pole mounted camera should be:
1) lightweight;
2) provided with a portable, daylight viewable screen;
3) colour with a minimum resolution of 0.3 megapixels;
4) equipped with a minimum of 200:1 zoom with integral lighting providing an in-pipe view range of at
least 70m in optimal conditions;
5) provided with the ability to record video and still photographs; and
6) provided with an integral or supplementary wide angle lens and lighting for the inspection of
chambers.
6.10.2
The following equipment may be useful for the field survey:
1) a metal detector for finding buried chamber covers;
2) an appropriate means for opening and lifting chamber covers, depending on the local health and
safety requirements;
3) binoculars for the remote inspection of inaccessible assets;
4) a means of determining pipe connectivity, either:
a) tracing dye; or
b) a pipe locator transmitter sonde with push rods and a handheld surface detector.
Method of survey
6.11
Working from the verge, hard shoulder, footpath, adjacent earthworks or adjacent land, and taking
advantage of any over-bridges, the surface visible point, continuous and region drainage assets shall
be located or confirmed.
6.11.1
The assets should be located and recorded as follows:
1) locate accessible surface visible point assets by GPS;
2) locate inaccessible surface visible point assets in the carriageway or central reserve by rangefinder
linked to the GPS, or from the aerial photography in the GIS;
3) locate straight surface visible continuous assets by joining the relevant point assets at their ends;
4) locate curved surface visible continuous assets by recording enough points along their length to
define their approximate shape and by using the aerial photography in the GIS;
5) for region assets record enough locations to adequately define their shape or trace around the
outline on the aerial photography in the GIS.
6.12
All accessible chamber covers shall be lifted and all incoming and outgoing pipes in the chamber
inspected using the pole mounted camera.
6.13
For each pipe the pole mounted camera shall be progressively zoomed along the pipe as far as visibility
permits to assess its condition and to take one or two photographs to illustrate the typical condition.
6.14
All mandatory data fields for asset inventory and survey parameters shall be recorded for all drainage
assets using the codes and formats detailed by the Overseeing Organisations in the NAAs to CD 535
[Ref 1.N].
6.14.1
Where there is no physical point asset at one end of a continuous asset, or it is buried and uncertain
then these point items may be assigned as ghost nodes.
6.14.2
Where the drainage network is dry and the flow direction is not obvious from the configuration of the
assets, then uncertainty in the flow direction should be recorded in accordance with Table 6.14.3.
33
CS 551 Revision 0
6.14.3
6. All assets condition and connectivity survey
The full connectivity of the drainage system should be established by a combination of inspection,
deduction and assumption and be recorded in accordance with Table 6.14.3 as follows:
1) where there is significant uncertainty in the connectivity then dye tracing or a pipe locator sonde is
used to resolve the uncertainty (within the limitations of safe access);
2) extreme uncertainty in the connectivity is indicated using a phantom connector;
3) even where connectivity is uncertain, the flow direction can be certain from an overall understanding
of the drainage network.
Table 6.14.3 Recording the level of certainty in connectivity and flow direction
Observation
Continuous
asset type and
details
Surface ditch or
channel.
Connection
certain.
Appropriate asset
type. Record the
mandatory and
optional asset
attributes.
Pipe, both ends
inspected.
Connection
certain. No
alternatives exist.
Appropriate pipe
asset type.
Record the
mandatory and
optional pipework
attributes.
A carrier pipe has
been inspected
from one or both
ends. Gullies are
present in the
carriageway but
cannot be
accessed. Gully
connections can
be seen in the
carrier but their
condition cannot
be assessed.
Use the general
pipework asset
type for both the
carrier pipe and
gully connections.
Having seen at
least some of the
gully connections
in the carrier pipe
a reasonable
assumption can
be made on the
location of the
connector node
between the
carrier and the
gully connections.
Record the
mandatory and
optional pipework
attributes for the
carrier. Record
only the
mandatory
attributes for the
gully connections.
Flow
certainty
Structural and
service grades
Certain
Likely to be
certain
Assign grades 1
to 5
Certain
Likely to be
certain
Assign grades 1
to 5
Certain
Likely to be
certain
Assign grades 1
to 5 to the carrier
and grade 9 to the
gully connections
Connectivity
certainty
34
CS 551 Revision 0
6. All assets condition and connectivity survey
Table 6.14.3 Recording the level of certainty in connectivity and flow direction (continued)
Observation
Continuous
asset type and
details
No below ground
inspection
possible due to
lack of access. A
line of gullies can
be seen along the
central reserve. A
carrier pipe
connecting them
is inferred
remotely from the
hard shoulder.
Use the general
pipework asset
type for the
carrier pipe and
record only the
mandatory
pipework
attributes. Use
the connectivity
attribute of the
gully to note its
connection to the
carrier pipe,
without the need
to record gully
connection
pipework or to
define the location
of the connection
between the two.
No below ground
inspection
possible due to
lack of access.
Dye tracing or
locator sonde is
either not
possible or has
not resolved the
connections. Two
or more
alternative
connections are
possible.
Use the general
pipework asset
type. It is
necessary to
make an
assumption at the
most likely
connection.
Record only the
mandatory
pipework
attributes.
Connectivity
certainty
Certain
Uncertain
Flow
certainty
Structural and
service grades
Likely to be
certain
Assign grade 9 to
the carrier
Can be certain or
uncertain
depending on
understanding of
the overall flow
regime
Assign grade 9
6.14.4
Any optional data fields for asset inventory and survey parameters should be recorded using the codes
and formats detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] so far as this is
possible within the constraints of safe access.
6.15
The overall asset level service and structural condition of every drainage asset shall be assessed in
accordance with the drainage condition grade quick assessment procedure given in Appendix B.
6.15.1
The condition of visible but inaccessible surface assets (such as channels in the central reserve) may
be assessed remotely from the verge or an overbridge with the aid of binoculars.
6.15.2
Where the asset condition cannot be assessed, such as inaccessible chambers in the central reserve
or ditches hidden in dense vegetation, then both condition grades should be recorded as "9".
6.15.3
Where an asset, such as a chamber, is known to exist from the desk study but cannot be found, then
both condition grades should be recorded as "0".
6.15.4
Where either a service or structural condition grade of 4 or 5 is assessed then the most severe defect
or defects that have lead to the grade assessment should be recorded and photographed.
35
CS 551 Revision 0
6. All assets condition and connectivity survey
6.16
Digital photographs shall be taken of all priority assets.
6.16.1
Digital photographs should be taken to show typical non-priority assets, and their condition.
Interruption of survey
6.17
Where the continuation of the survey is prevented by a temporary increase in the flow rate in the
drainage system the survey shall either:
1) move to another location either within the same catchment or another catchment whilst the flow
abates; or
2) be suspended until the flow has abated where all parts of the drainage systems to be surveyed are
temporarily affected.
6.18
Where access to the pipework is obstructed by silt or muddy water and the pipework cannot be
inspected by the pole camera the survey shall:
1) record the service and structural condition of the chamber;
2) record that the pipework was not accessible for survey (service and structural condition grade 9);
3) not attempt to clear the chamber;
4) move to the next survey position; and
5) survey the pipework from adjacent nodes where possible.
6.19
Where a blockage is encountered within pipework the survey shall:
1) record the service and structural condition of the pipework;
2) not attempt to clear the blockage;
3) move to the next survey position;
4) survey the pipework from the opposite end; and
5) reassess the overall pipework service and structural condition.
6.20
Where a chamber cover or gully grating cannot be removed within 15 minutes the survey shall:
1) record that the node was not accessible for survey (structural and service condition grade 9);
2) move to the next survey position; and
3) survey the pipework from adjacent nodes.
6.21
Where a chamber is found to be unsafe to use as an access point the survey shall:
1) record the service and structural condition and photograph the chamber from the surface; and
2) survey the pipework from adjacent nodes.
Quality control requirements
Surveyor competency
6.22
The senior surveyor shall have at least five years experience of surveying highway drainage systems.
6.22.1
The senior surveyor should be able to make informed judgement about the nature and connectivity of
the drainage asset for those parts of the drainage system that cannot be directly accessed during the
survey.
6.23
Evidence shall be provided that the surveyor undertaking the pole mounted camera survey has
received training in the use of the equipment and the interpretation of drainage condition.
NOTE
Develop Training Ltd's OS19X pipe sewer condition classification or OS30X pipe sewer condition
conversion qualifications are appropriate.
36
CS 551 Revision 0
6. All assets condition and connectivity survey
Survey method quality control
6.24
As the survey of each drainage catchment is completed, the field GIS map shall be reviewed and any
gaps infilled and any anomalies resolved, before moving on to the next part of the survey.
NOTE
The survey can be checked for the following:
1) is the drainage network complete?;
2) are there any gaps?;
3) have outfalls and/or soakaways been located?;
4) are the flow directions consistent?;
5) are there areas where the flow direction is uncertain, which can now be re-assessed as certain?;
6) are there areas where the connectivity is uncertain, that warrant further inspection, or can now be
re-assessed as certain?;
7) have all the mandatory attributes been completed?;
8) has a structural and service grade been assigned to every asset, either 1 to 5, or 9 or 0?;
9) have the optional attributes been completed for all assets that it was possible to access?
Reporting requirements
Data submission
6.25
Unless detailed otherwise in the schedule of requirements the survey report shall consist of a
submission for upload to the DDMS of the following digital data:
1) the round-tripped DDMS survey data (if any) combined with the new survey data as separate files
for each catchment;
2) any digital photographs taken during the survey.
Survey data
6.26
All survey data shall be reported using the standard coding system and nomenclature defined by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
6.27
All recorded survey data shall be submitted for upload to the DDMS in the standard digital format(s)
defined by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
6.28
Where a section of pipework between consecutive nodes is surveyed from each end, then two separate
coding records shall be made and combined to form a single record of the pipework between the two
nodes.
6.28.1
Automated combination of condition records should be carried out by the reporting software or by the
DDMS during data upload.
6.29
Any round-tripped existing drainage data from the DDMS shall retain the unique reference of each
asset.
6.30
New assets added to the data during the survey shall be assigned a field reference that is unique within
the survey.
NOTE
A permanent unique asset reference is automatically assigned by the DDMS when the data is
uploaded.
Photographs
6.31
All photographs shall be:
1) in colour;
2) in JPEG format as .JPG files;
37
CS 551 Revision 0
6. All assets condition and connectivity survey
3) submitted for upload to the DDMS as documents attached to the asset to which they relate;
4) at a resolution of at least 1.0 megapixels, and
5) indexed in the coded data.
38
CS 551 Revision 0
7.
7. Pipework and chambers defect survey by CCTV
Pipework and chambers defect survey by CCTV
Survey requirements
Scope of survey
7.1
A pipework and chambers defect survey shall be carried out to determine the inventory, condition and
detailed defects of pipework and the associated chambers and gullies, including the use of a closed
circuit television (CCTV) camera.
7.2
A pipework and chambers defect survey by CCTV shall include the following (unless detailed otherwise
in the schedule of requirements):
1) details of the location, date, equipment and personnel of the survey;
2) details of any pre-cleansing, removal of blockages, root cutting or other associated works carried out;
3) survey of the required pipework and/or culverts;
4) survey of all chambers and gullies connected to the required pipework and/or culverts and
associated interconnections;
5) survey of the location of all chambers and gullies and the levels of chamber covers, gully gratings,
chamber inverts, gully inverts and the inverts of pipework connections;
6) identification of the asset type of all surveyed assets in accordance with the classification system
detailed in CD 535 [Ref 1.N];
7) recording of all the mandatory and optional data fields for asset inventory, structural condition
defects, service condition defects, and survey parameters using the codes detailed by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] for all pipework and/or culverts,
chambers and gullies surveyed;
8) recording of an overall asset level structural and service condition grade;
9) recording of an in-pipe video showing the nature of the pipework and the defects recorded;
10) taking of still photographs from the in-pipe video showing the nature of typical pipework and specific
defects recorded;
11) taking of still photographs showing the typical nature and specific defects of the chambers and
gullies surveyed;
12) submission of a digital report and digital data sets in the formats defined by the Overseeing
Organisations in the NAAs to CD 535 [Ref 1.N] and as detailed in the reporting requirements below.
NOTE
A pipework and chambers defect survey by CCTV is:
1) a field survey carried out where full and detailed knowledge of the condition and defects of the below
ground pipework is needed;
2) carried out because, either;
a) there is a known problem with the performance of the pipework that needs to be understood; or
b) there is flooding or defects in other assets that are suspected to be due to defective pipework; or
c) an all assets condition and connectivity survey has indicated a structural or service grade of 4 or
5 within the pipework that requires further investigation; or
d) repair, replacement or redesign of the drainage system is being investigated; or
e) for contractual certification of new build drainage works.
3) applicable in all forms of pipework up to 900mm in diameter and in culverts up to 1800mm in
diameter.
7.2.1
A pipework and chambers defect survey by CCTV may include the following (where required in the
schedule of requirements):
1) the provision of traffic management;
2) restrictions to the work programme and/or working hours.
39
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
Survey data round-tripping
7.3
Survey data shall be round-tripped from the DDMS where available.
7.4
Where there is some drainage inventory information in the catchment(s) to be surveyed on the DDMS
the survey shall round-trip this data in accordance with specific procedures and formats detailed by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] by:
1) downloading the available information;
2) confirming or updating the inventory, condition and defects of the pipework, culverts and associated
chambers and gullies in the field;
3) retaining as part of the data, without change, any inventory and condition information on any
non-surveyed assets; and
4) the submission for uploading of this information to the DDMS.
7.5
Where there is no drainage inventory information in the catchment(s) to be surveyed on the DDMS the
survey shall consist of the following:
1) a first time survey of the inventory, condition and defects of the pipework, culverts and associated
chambers and gullies;
2) the submission for upload of this information to the DDMS in accordance with specific procedures
and formats detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
7.6
Where the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] require additional activities to
complete the round-tripping of drainage information to the DDMS these shall be carried out as part of
the survey.
Survey equipment
7.7
The CCTV equipment shall be capable of surveying:
1) a length of pipework of at least 350 metres where the pipework can be accessed from either end;
2) a length of pipework of at least 200 metres where a self-propelled camera is used and access is
gained from only one end; or
3) a length of pipework of at least 30 metres where a rodding camera is used.
7.8
The CCTV camera shall be:
1) crawler, tractor or sledge mounted;
2) equipped with integral lighting unit;
3) certified for use in either Zone 1 or Zone 2 potentially explosive environments as required in the
schedule of requirements;
4) equipped with a pan, tilt and zoom facility capable of 90 degrees tilt and 360 degrees rotation,
unless stated otherwise in the schedule of requirements;
5) colour, solid state, with a resolution of at least 0.4 megapixels;
6) capable of producing a clear, accurate and in focus record of the internal condition of the pipework
from 150mm in front of the camera to infinity;
7) equipped with a cable connecting the camera to the surface control unit through a counter to
determine the camera location;
8) set up to pass through the pipework being surveyed in a stable manner;
9) positioned so as to minimise the risk of picture distortion by being positioned centrally within the
pipework to within a positioning tolerance of ±10% of the vertical pipework dimension and looking
along the axis of the pipework; and
10) set up so that all bonds, guide ropes and cables are supported away from the walls of the pipework
and chambers.
40
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
7.9
The location of the CCTV camera within the pipework shall be measured to an accuracy of ± 1% the
length of the pipe run or 0.3m whichever is the greater, with the counter reading at the start of the survey
run set to zero by allowing for the distance from the start of the survey run to the cable calibration point.
7.10
The CCTV monitor shall display an automatically updated record of the following reference information
which is to be shown on the recorded video and photographs:
1) the chamber reference at the start of the survey run;
2) the chamber reference at the end of the survey run (whether the chamber is reached or not);
3) the pipe reference;
4) the survey direction;
5) the survey run reference (to distinguish multiple survey runs on the same pipe in the same direction);
6) the chainage of the camera position from the calibration point in metres and tenths of a metre;
7) the date of survey.
7.11
The computer based CCTV recording equipment shall be capable of the following:
1) digitally recording a video of the CCTV image overlaid with the reference information;
2) digitally recording still photographs from the video overlaid with the reference information;
3) recording the CCTV surveyor's interpretation of the inventory and condition of the pipework using
the codes detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N];
4) linking the recorded video and still photographs to the coded data.
7.12
Topographic survey equipment shall be provided to measure locations and levels to the accuracy
stated in CD 535 [Ref 1.N] for detailed survey and to the national survey grid and national survey datum
stated by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
7.13
Facilities shall be provided for the forced ventilation of pipework or culverts where required by the
schedule of requirements.
7.14
Off-road survey vehicles shall be provided where required by the schedule of requirements.
Method of survey - pipework CCTV
7.15
Pre-cleansing of the drainage system shall be carried out where required in the schedule of
requirements.
7.16
Pre-cleansing shall be carried out in accordance with the MCHW Vol. 1 Series 500 2009 [Ref 6.N]
clauses on the cleaning of existing drainage systems and low pressure high volume jetting of drainage
systems.
7.17
The location and depths of silt removed by pre-cleansing shall be recorded and reported.
7.17.1
Pre-cleansing can remove evidence of siltation problems or other service defects that affect the
performance of the pipework and should only be carried out where it is known that the silt level
prevents access by the CCTV camera.
7.18
The pipework shall be vented to remove potentially noxious or explosive gases by raising the covers at
both ends of the length to be surveyed.
7.19
The inventory and condition of all required pipework lengths shall be surveyed by CCTV and reported
by recording all of the mandatory and optional data fields for asset inventory, structural condition
defects, service condition defects, and survey parameters using the codes detailed by the Overseeing
Organisations in the NAAs to CD 535 [Ref 1.N].
7.20
At each chamber or other access point, new pipework header details shall be recorded, except for gully
connections which are recorded in accordance with CD 535 [Ref 1.N].
7.21
Where buried chambers are encountered during the survey, the camera shall be panned to allow
recording of the internal inventory and condition of the chamber.
41
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
7.22
Where the survey continues through a chamber or other access point, the meterage shall be reset to
zero with the camera focused on the outgoing pipe entrance.
7.23
The length of pipework shall be measured between the exit face of one chamber and the point of entry
to the next chamber.
7.24
The speed of the camera within the pipework shall be limited to the following maximum speeds:
1) 0.10m/s for pipework of diameter less than 200mm;
2) 0.15m/s for pipework of diameters of 200mm or larger but less then 310mm;
3) 0.20m/s for pipework or culverts of diameter 310mm and larger.
7.25
The camera shall be stationary whenever observations are being recorded.
7.26
Where a camera with pan and tilt head is used the camera shall:
1) only be moved forward when the lens is pointing forward in the direction of the axis of the pipework;
and
2) be stopped and panned around the circumference of the whole pipe to inspect a defect or
connection.
7.27
Still photographs shall be taken of the internal condition of the pipework as follows:
1) at the start of all continuous defects, and thereafter every 5m;
2) for non-brick pipework or culverts at every crack, fracture, broken pipe, deformation, collapse and
severe joint displacement;
3) for brick pipework or culverts at every crack, fracture, missing or displaced brick, deformation,
collapse, dropped invert and mortar loss;
4) at any other structural or service defect that would lead to the overall grading of the pipework or
culvert being 3, 4 or 5;
5) at intervals not less than 2 metres where defects exist at adjacent points unless necessary to show
the second defect;
6) to show the general condition at intervals of not more than 10 metres where there are no defects;
7) at abandonment;
8) all photographs are recorded in the coded data.
7.28
All equipment and debris shall be removed from site at the end of each shift, or sooner.
Method of survey - chambers
7.29
All chamber covers and gully gratings shall be removed and replaced to gain access for the survey.
7.30
The inventory and condition of all chambers and gullies connected to the required pipework shall be
surveyed by visual inspection from the surface and reported by recording all of the mandatory and
optional data fields for asset inventory, structural condition defects, service condition defects, and
survey parameters using the codes detailed by the Overseeing Organisations in the NAAs to CD 535
[Ref 1.N].
7.31
The location of all chambers shall be surveyed to the accuracy stated in CD 535 [Ref 1.N] for detailed
survey and to the national survey grid stated by the Overseeing Organisations in the NAAs to CD 535
[Ref 1.N].
7.32
The level of all chamber covers, gully gratings, manhole inverts, gully sumps, catchpit sumps, inverts of
all incoming and outgoing pipework connections in every chamber shall be surveyed to the accuracy
stated in CD 535 [Ref 1.N] for detailed survey and to the national survey datum stated by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
7.33
Photographs shall be taken of all chambers and gullies surveyed as follows:
1) general location photograph of the chamber/gully prior to removal of the cover/grating;
42
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
2) vertical photograph looking down the chamber/gully with cover/grating removed, prior to any
cleaning;
3) vertical photograph looking down the chamber/gully with cover/grating removed, following any
cleaning;
4) additional photographs to show specific defects;
5) orientation of photographs to be recorded along with direction of flow;
6) photographs 1) to 3) above to be recorded as "general photograph" observations.
Interruption of survey
7.34
Where the continuation of the survey is prevented by a temporary increase in the flow rate in the
drainage system the survey shall either:
1) attempt to manage the flow within the pipework by means of temporary stoppers for limited periods
to facilitate the survey without causing flooding or pollution of receiving waters; or
2) move to another location whilst the flow abates; or
3) be suspended until the flow has abated.
7.35
Where the continuation of the survey is prevented by a blockage in the drainage system, the survey
shall proceed as detailed in the schedule of requirements, either:
1) do not attempt to remove the blockage and survey the pipework run from the other direction; or
2) move to an another location whilst the blockage is cleared by others as arranged by the Overseeing
Organisation's representative; or
3) survey the pipework run from the other direction, then proceed to remove the blockage by cleansing
as follows:
a) cleansing of catchpits and manholes to be in accordance with the MCHW Vol. 1 Series 500 2009
[Ref 6.N] clauses on the cleaning of existing drainage systems;
b) cleansing of pipework to consist of low pressure/high volume jetting in accordance with the
MCHW Vol. 1 Series 500 2009 [Ref 6.N] clauses on low pressure high volume jetting of drainage
systems;
c) jetting nozzle pressures are not to exceed 127 bar/1900 psi or any lower value stated in the
MCHW Vol. 1 Series 500 2009 [Ref 6.N] clauses on low pressure high volume jetting of drainage
systems.
7.36
Where initial inspection indicates root blockage or partial blockage, root cutting shall be carried out
where specified in the schedule of requirements and the pipework resurveyed, by either:
1) jetting with the nozzle pressures not to exceed 127 bar/1900 psi or any lower value stated in the
MCHW Vol. 1 Series 500 2009 [Ref 6.N] clauses on low pressure high volume jetting of drainage
systems; or
2) flail; or
3) other form of cutter.
7.37
Where a chamber cover or gully grating cannot be removed within 15 minutes the survey shall:
1) survey the node by CCTV from the adjacent nodes; or
2) where surveying of the node is not possible, record that the node was not accessible for survey
(structural and service condition grade 9) and move to the next node.
7.38
Where a chamber is found to be unsafe to use as an access point then the survey shall:
1) record the service and structural condition and photograph the chamber from the surface; and
2) survey the pipework from adjacent nodes.
7.39
Where continuation of the survey is prevented by temporary traffic conditions, parked vehicles or other
obstructions, or changes in the traffic management arrangements the surveyor shall either:
43
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
1) attempt to resolve the matter with those responsible for traffic management as detailed in the
schedule of requirements; or
2) move to another location whilst the matter is resolved; or
3) be suspended until the matter is resolved.
Abandonment of survey
7.40
A survey run of any pipework length shall be abandoned for any of the following reasons:
1) it is not possible to maintain acceptable picture quality due to the condition of the pipework;
2) a situation occurs that places the survey equipment or personnel at risk;
3) further progress is impossible;
4) it is not possible to locate the access point;
5) it is not possible to lift the access chamber cover;
6) it would be unsafe to access the pipework due to the condition of the access chamber;
7) it is not possible to survey from the chamber or continue the survey due to blockage, silt or high
water level;
8) a dangerous atmosphere is identified in the pipework;
9) there is a risk to the structural integrity of the pipework.
7.41
Where a survey run has the potential to be abandoned then the following shall be carried out:
1) recording of the situation on the survey record;
2) photographing of the issue;
3) adoption of the procedures for interruption of survey prior to abandonment;
4) only where the interruption of survey procedures are unsuccessful or not possible is the survey of
this section of pipework to be abandoned and the Overseeing Organisation's representative
informed.
Quality control requirements
Surveyor competency
7.42
Evidence shall be provided that the surveyor undertaking the CCTV survey holds an appropriate
qualification in the interpretation of CCTV images of pipework and in defect coding and classification.
NOTE
Develop Training Ltd's OS19X pipe sewer condition classification or OS30X pipe sewer condition
conversion qualifications are appropriate.
7.43
Evidence shall be provided that the surveyor undertaking the location and level topographic survey
holds an appropriate qualification in topographic surveying.
7.44
Where any working within confined spaces is required, evidence shall be provided that those staff
involved have received appropriate confined space training.
7.45
A quality control system approved by the Overseeing Organisation's representative shall be maintained
to control the accuracy of the CCTV interpretation and reporting consisting of the following:
1) monitoring a 5% sample of each surveyor's work;
2) selecting the sample randomly from the sequence of work carried out by each surveyor;
3) independent review of the video recordings against the coded data in the sample;
4) derivation of header accuracy as the proportion of entries made in the header fields which are
entered using the correct symbols or codes, for the sample;
5) derivation of the detailed survey accuracy as the proportion of entries that are correct, with any
missing entry regarded as incorrect, for the sample;
44
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
6) where the accuracy of either the header information calculated for any of the sampled surveys falls
below 95% or the coded detailed survey information calculated for any survey falls below 85%, an
additional check is carried out;
7) the additional check comprising the five surveys of pipework lengths carried out by that surveyor
immediately preceding the failed survey and the five surveys carried out by that surveyor
immediately following the failed survey;
8) where any of these additional checks fail then the process is repeated using a further five before and
after surveys, until the required accuracy is achieved;
9) the individual check results for both the header and detailed survey information and the rolling
average of both of these over each five consecutive checks is plotted on a graph and reviewed.
7.46
A CCTV surveyor whose header quality control results fall below 95% or whose detailed survey quality
control results fall below 85% on more than two occasions in a 3 month period, or whose rolling average
for either check falls below these criteria, shall be deemed to have failed the quality control criteria.
7.47
A CCTV surveyor who fails the quality control criteria shall be invalidated from acting as a surveyor on
any contract until they have re-attended and re-passed the relevant training.
7.48
Any CCTV survey reports failing the coding accuracy shall be re-coded by another qualified surveyor
and re-submitted as a replacement for the failed survey.
Survey method quality control
7.49
A method statement shall be provided and approved prior to the commencement of the works that
includes the following:
1) a statement of full compliance with this specification or a clear list of any qualifications or
non-compliance of either equipment or procedures, and a full method statement of any alternatives
proposed;
2) the type and version of the CCTV survey software;
3) any sub-contractors that are to be used and a description of their role.
7.50
The accuracy of the linear measurement of the camera position shall be checked and recorded by the
procedure for camera cable calibration defined in MSCC5 2013 [Ref 7.N].
7.51
Where the linear measurement of the camera position falls outside of the required accuracy the
pipework shall be resurveyed.
7.52
The camera shall be set up in the pipework at the start of each survey run by the procedures defined in
MSCC5 2013 [Ref 7.N] for the following:
1) centring the camera;
2) measuring the offset distance of the camera;
3) positioning the camera at the start of the pipe.
CCTV picture quality control
7.53
The electronic equipment, camera and monitor shall be set up and tested by the procedures defined in
MSCC5 2013 [Ref 7.N] for the following:
1) video display screen test;
2) camera test;
3) lighting test.
Reporting requirements
Data submission
7.54
Unless detailed otherwise in the schedule of requirements, the survey report shall consist of the
following digital data submitted via the internet split into drainage catchments suitable for upload to the
DDMS:
45
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
1) coded survey data in the digital format(s) defined by the Overseeing Organisations in the NAAs to
CD 535 [Ref 1.N], as detailed in the survey data requirements;
2) video recordings referenced in the coded survey data, as detailed in the video recordings
requirements;
3) photographs referenced in the coded survey data, as detailed in the photographs requirements;
4) an optional report in PDF format detailed in the report requirements (only if required by the schedule
of requirements);
5) optional CAD drawings detailed in the CAD drawings requirements (only if required by the schedule
of requirements).
Survey data
7.55
All survey data shall be reported using the standard coding system and nomenclature defined by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
7.56
All coding shall be directly entered into a computer or handheld device that restricts entries to valid
codes.
7.57
Where the survey is round-tripping existing drainage data from the DDMS the unique reference of each
asset shall be retained in the round-tripped data.
7.58
Where new assets are added to the data during the survey they shall be assigned a field reference that
is unique within the survey.
NOTE
A permanent unique asset reference is automatically assigned by the DDMS when the data is
uploaded.
7.59
At the commencement of the survey of every length of pipework or culvert between consecutive access
points, the surveyor shall complete new header information in accordance with the requirements of the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
7.60
Where different observation types occur at the same point each shall be coded separately.
7.61
Where a continuous observation changes in nature along its length, the change shall be coded
separately.
7.62
The length of pipework shall be measured between the exit face of the chamber and the point of entry
to the next chamber.
7.63
Where a section of pipework is surveyed more than once either due to obstruction or equipment
difficulties then the last survey run shall be reported.
7.64
Where a section of pipework between consecutive nodes is surveyed from each end due to obstruction,
then two separate coding records shall be made and combined to form a single record of the pipework
between the two nodes.
7.64.1
Automated combination of condition records should be carried out by the reporting software or by the
DDMS during data upload.
7.65
Each of the defects recorded shall be scored in accordance with the scoring system detailed by the
Overseeing Organisations in the NAAs to CD 535 [Ref 1.N] for all pipework and/or culverts, chambers
and gullies surveyed.
7.65.1
Automated condition scoring should be carried out by the recording software or by the DDMS during
data upload.
7.66
The overall asset level structural and service condition grade shall be derived by aggregating the
scores for each recorded defect in accordance with the aggregating procedure detailed in CD 535 [Ref
1.N] for all pipework and/or culverts, chambers and gullies surveyed.
7.66.1
Automated aggregation of the scores to determine the overall asset level structural and service
condition grades should be carried out by the CCTV software or by the DDMS during data upload.
46
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
7.67
All recorded survey data shall be submitted for upload to the DDMS in the standard digital format(s)
defined by the Overseeing Organisations in the NAAs to CD 535 [Ref 1.N].
7.68
Unless detailed otherwise in the schedule of requirements the survey data shall also be provided
packaged with any proprietary software viewer necessary to view all of the data in accordance with the
following:
1) all of the coded data (both header and detailed defect observations) for every inspection carried out
on every section of pipework, culvert, chamber, and gully, including repeat inspections;
2) all of the associated photographs and videos;
3) facilities that allow the survey data to be viewed in conjunction with the video and photographs, such
that viewing an asset or observation in the data will automatically retrieve the associated section of
video and relevant photographs;
4) an unrestricted licence for the use of the software viewer.
7.69
Where required by the schedule of requirements items of the survey data shall be supplied in advance
of the formal report during the course of the survey.
Video recordings
7.70
All video recordings shall be:
1) in colour;
2) in MPEG format as .MPG files;
3) at a resolution of at least 0.4 megapixels;
4) at a frame rate of at least 25 frames per second; and
5) indexed in the coded data.
Photographs
7.71
All photographs taken shall be submitted for upload to the DDMS as documents attached to the asset
to which they relate.
7.72
All photographs shall be:
1) in colour;
2) in JPEG format as .JPG files;
3) at a resolution the same as the video recording for CCTV survey;
4) at a resolution of at least 1.0 megapixels for all other photographs; and
5) indexed in the coded data.
Report (optional)
7.73
A summary report in PDF format shall additionally be provided where required by the schedule of
requirements, including the following:
1) a description of the survey carried out, its location, and the equipment and methods used;
2) details of the quality control procedures;
3) a schematic drawing of each section of pipework or culvert surveyed showing the reference number,
diameter and material of the pipe, the location and nature of each structural and service defect, the
position of any adjoining connections, the reference numbers of the chamber/node at each end, the
flow direction and the overall structural and service grade of the pipe;
4) a schematic drawing of each chamber in plan and section showing the position, references and
invert levels of all incoming and outgoing pipes, the level of any water and/or silt, the position and
nature of any defects and the overall structural and service grade of the chamber;
47
CS 551 Revision 0
7. Pipework and chambers defect survey by CCTV
5) details of the coded defects for each asset surveyed in tabular format;
6) a summary table of all pipework/culverts surveyed (including abandoned surveys) detailing the pipe
asset reference, the asset references of the upstream and downstream chambers, the upstream and
downstream invert levels, the survey direction, date, the pipe shape, size and material, the total
length of the pipe, the length of the pipe surveyed, the overall structural and service grade;
7) a summary table of abandoned pipework/culvert surveys detailing the pipe asset reference, the
asset references of the upstream and downstream chambers, total length of the pipe, surveyed
length at abandonment, reason for abandonment;
8) a summary table of pipe jetting and root cutting detailing the pipe asset reference, the asset
references of the upstream and downstream chambers, the cleansing direction, date, start of
blockage (m), end of blockage (m), length jetted (m), duration of root cutting, equipment used,
maximum pressure used, nature of blockage and outcome;
9) a summary table of all chambers and gullies surveyed detailing the asset reference, asset type,
cover level, invert level, the overall structural and service grade.
CAD drawings (optional)
7.74
CAD drawings in DXF and PDF formats shall additionally be provided where required by the schedule
of requirements, showing the following:
1) the extent of the completed survey;
2) the location and unique reference number of each drainage asset surveyed;
3) the overall service and structural condition grade of each asset;
4) any errors in any provided drawings or layout data noted during the survey;
5) overlaid on available base mapping showing the highway, highway boundary, structures and other
reference features of the surveyed corridor and the national grid.
48
CS 551 Revision 0
8.
8. Pipework geometric survey by laser profiler
Pipework geometric survey by laser profiler
Survey requirements
Scope of survey
8.1
A pipework geometric survey shall be carried out to determine the internal circumferential geometry,
including the use of a laser profiler in association with a CCTV survey.
8.2
A pipework geometric survey by laser profiler shall include the following (unless detailed otherwise in
the schedule of requirements):
1) the survey of the internal circumferential pipework geometry;
2) the recording of any additional mandatory and optional data fields for asset inventory, structural
condition defects, service condition defects and survey parameters either not recorded or not fully
quantified by the associated CCTV survey, and the merging of these observations into the CCTV
coded data using the codes detailed by the Overseeing Organisations in the NAAs to CD 535 [Ref
1.N];
3) the assessment and reporting of internal pipework diameter, cross sectional area, ovality and
surface irregularities.
NOTE
A pipework geometric survey by laser profile is carried out:
1) in association with a pipework and chambers defect survey by CCTV;
2) where continuous measurement of the internal geometry of the below ground pipework is required;
3) in all forms of pipework up to 900mm in diameter and in culverts up to 1800mm in diameter.
Survey data round-tripping
8.3
Survey data shall be round-tripped from the DDMS, where available, in accordance with the
requirements for pipework and chambers defect survey by CCTV.
Survey equipment
8.4
A laser profiler shall be:
1) attached to a crawler, tractor or sledge mounted CCTV camera;
2) equipped with a single or multiple laser sources (as suited to the diameter of the pipework) to define
a bright ring of light on the internal circumference of the pipework within the view of the CCTV
camera;
3) certified for use in either Zone 1 or Zone 2 potentially explosive environments as required in the
schedule of requirements;
4) capable of recording the pipework internal circumferential profile to an accuracy of +/-1%, at
intervals of no more than 10mm along the length of the pipework, with a resolution of at least 180
data points per profile.
Method of survey
8.5
Pre-cleansing of the drainage system shall be carried out where required in the schedule of
requirements.
NOTE
Optimum laser profile results are obtained in clean and dry pipes, but the use of pre-cleansing can be
at variance with the optimum conditions for recording service condition by the associated CCTV survey,
therefore the sequencing of the works is to be determined.
8.6
The internal circumferential geometry of the pipework shall be surveyed by laser profiler making two
passes along the pipe length, one with the CCTV lights on and one with them off, traversing the pipe at
a constant speed.
49
CS 551 Revision 0
8.7
8. Pipework geometric survey by laser profiler
The distance recording shall be synchronised for:
1) the two passes along the pipework; and
2) between observations made from the CCTV video; and
3) those made from the laser profile interpretation, allowing for the offset of the laser in front of the
camera.
Interruption of survey
8.8
Interruptions to the survey shall be defined and managed in accordance with the requirements for
pipework and chambers defect survey by CCTV.
Abandonment of survey
8.9
Abandonment of the survey shall be defined and managed in accordance with the requirements for
pipework and chambers defect survey by CCTV.
Quality control requirements
Surveyor competency
8.10
Evidence shall be provided that the surveyor undertaking the laser profile survey has received training
in the use of the equipment and the interpretation of the results.
Survey method quality control
8.11
The calibration of the measurement of internal pipework diameter by the laser profiler shall be checked
and recorded at the start of each survey run by:
1) manually measuring the pipework diameter along two diameters at right angles; and
2) using a calibration scale placed on the laser head.
8.12
The associated CCTV camera and video recording shall be set to its maximum visual resolution.
8.13
The summary outputs of diameter, cross sectional area, ovality and unwrapped irregularity shall be
annotated where the results are misleading due to water and/or sediment in the pipe invert or other
factors.
Reporting requirements
Data submission
8.14
Unless detailed otherwise in the schedule of requirements, the survey report shall consist of the
following digital data submitted via the internet split into drainage catchments suitable for upload to the
DDMS:
1) a summary report in PDF format, as detailed in the report requirements;
2) the coded survey data merged into the coded survey data from the CCTV survey, as detailed in the
survey data requirements;
3) CAD files, as detailed in the CAD file requirements.
Report
8.15
A summary survey report shall be provided in PDF format including the following:
1) a description of the survey carried out, its location, and the equipment and methods used;
2) details of the quality control procedures;
3) graphical plots showing the average, minimum and maximum internal diameter as a percentage
(positive or negative) change from the nominal undeformed diameter along the length of each
surveyed pipe (measured in m from the upstream end);
50
CS 551 Revision 0
8. Pipework geometric survey by laser profiler
4) graphical plots showing the percentage change in cross sectional area (positive or negative) from
the nominal undeformed cross sectional area along the length of each surveyed pipe (measured in
m from the upstream end);
5) graphical plots showing the percentage ovality along the length of each surveyed pipe (measured in
m from the upstream end) for those pipes that were originally circular in cross section;
6) coloured graphics showing irregularities in the internal circumferential surface of each pipe
unwrapped as a flat representation, colour coded with the (positive and negative) percentage
difference from the nominal undeformed radius along the length of each surveyed pipe (measured in
m from the upstream end).
NOTE
mean
Percentage ovality of the original pipe is defined as: △ = 100 ∗ DmaxD−D
, where Dmax is the maximum
mean
internal diameter and Dmean is the mean internal diameter ( ASTM F1216-16 [Ref 1.I]).
Survey data
8.16
All coded survey data shall be reported merged with the CCTV coded data in accordance with the
requirements for pipework and chambers defect survey by CCTV.
8.17
Unless detailed otherwise in the schedule of requirements, the survey data shall also be provided
packaged with any proprietary software viewer necessary to view all of the data in accordance with the
following:
1) the individual circumferential profiles for all locations along each pipe with facilities to carry out
manual measurements from the profiles;
2) for each pipe the summary diameter, cross sectional area, ovality and unwrapped irregularity
graphics defined for the summary PDF report;
3) a 3D graphical representation of the internal surface of each pipe colour coded with the (positive and
negative) percentage difference from the nominal undeformed radius that can be viewed from
various angles and at various magnifications;
4) facilities that allow the summary survey data to be viewed in conjunction with, and linked to, the
individual circumferential profiles, the CCTV video and photographs, and the coded observations;
5) an unrestricted licence for the use of the software viewer.
CAD files
8.18
A CAD file of the 3D graphical representation of the internal surface of each surveyed pipe shall be
provided in DXF file format.
51
CS 551 Revision 0
9.
9. Normative References
Normative References
The following documents, in whole or in part, are normative references for this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
Ref 1.N
Highways England. CD 535, 'Drainage asset data and risk management'
Ref 2.N
The National Archives. Legislation.gov.uk. SI 1713, 'Health and Safety. The Confined
Space Regulations 1997'
Ref 3.N
Highways England. GG 101, 'Introduction to the Design Manual for Roads and
Bridges'
Ref 4.N
HSE. MHSC 2015, 'Managing health and safety in construction'
Ref 5.N
MCHW Volume 5 Series 9000, 'Manual of Contract Documents for Highway Works.
Volume 5 Contract Documents for Specialist Activities. Section 9 Model Contract
Documents for CCTV Survey of Highway Drainage Systems. Part 4 Series 9000
Method of Measurement'
Ref 6.N
Highways Agency. MCHW Vol. 1 Series 500 2009, 'Manual of Contract Documents
for Highways Works. Volume 1 Specification for Highway Works. Drainage and
service ducts'
Ref 7.N
WRc. MSCC5 2013, 'Manual of Sewer Condition Classification 5th Edition'
Ref 8.N
EPSIUPEAR, 'The Equipment and Protective Systems Intended for Use in Potentially
Explosive Atmospheres Regulations 2016'
52
CS 551 Revision 0
10.
10. Informative References
Informative References
The following documents are informative references for this document and provide supporting
information.
Ref 1.I
American Society for Testing and Materials. ASTM F1216-16, 'Standard Practice for
Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a
Resin-Impregnated Tube'
Ref 2.I
The National Archives. legislation.gov.uk. DSEAR S.I. No. 2776, 'Statutory
Instrument No.2776 Health and Safety The Dangerous Substances and Explosive
Atmospheres Regulations 2002'
53
CS 551 Revision 0
Appendix A. Example schedule of requirements
Appendix A. Example schedule of requirements
The following provides an example of the items to be included in the schedule of requirements for a
drainage survey. Where options are available, a default selection is given that should be chosen unless
there is good reason to select one of the alternatives.
A1
General requirements
1) State the survey type, to be one or more of the following:
a)
b)
c)
d)
e)
f)
validation survey;
priority asset survey;
filter drain condition survey by GPR;
all assets condition and connectivity survey;
pipework and chambers defect survey by CCTV;
pipework geometric survey by laser profiler.
2) The location of the survey is to be detailed by:
a) stating the location of the survey, area name, road number, location within or adjacent to the
carriageway, marker post chainage; and
b) providing maps/plans/drawings showing the extent of the survey.
3) Detail any constraints on the works, including:
a)
b)
c)
d)
e)
f)
restrictions on access routes to the whole site, or sections of the site;
restrictions on the days or hours of working;
restrictions on the overall programme or sequencing of the works;
restrictions imposed by traffic management arrangements;
restrictions due to other works within the area; or
restrictions due to environmental or ecological constraints.
4) Define periods outside normal working hours.
5) Detail any variation in the scope of the survey works from that defined in this specification.
6) Provide pre-construction information covering the works.
7) State the classification of the site for the use of electrical equipment in potentially explosive
atmospheres, in accordance with DSEAR S.I. No. 2776 [Ref 2.I], either:
a) the site is classified as Zone 2 (default); or
b) the site is classified as Zone 1.
8) State the responsibility for traffic management, either:
a) by others arranged by the area management team (default); or
b) by others arranged by the Overseeing Organisation's representative; or
c) arranged by the survey team.
A2
Survey requirements
A2.1
General
1) State the requirement for survey data round-tripping, either:
a) some drainage inventory information in the catchment(s) to be surveyed is available on the
DDMS and round-tripping of this data is required (default); or
b) no drainage inventory information in the catchment(s) to be surveyed is available on the DDMS
and round-tripping of data is not required.
2) State the requirement for off-highway working not accessible by conventional two wheel drive
vehicles, either:
a) off-road vehicles are not required (default); or
b) off-road vehicles are required; or
54
CS 551 Revision 0
Appendix A. Example schedule of requirements
c) off-road vehicles may be required.
A2.2
Pipework and chambers defect survey by CCTV
1) State the requirement for pan and tilt CCTV camera, either:
a) pan and tilt CCTV camera required (default); or
b) fixed head panoramic view CCTV camera required.
2) State the requirement for forced ventilation of pipework and/or culverts, either:
a) forced ventilation will not be required (default); or
b) forced ventilation will be required; or
c) forced ventilation may be required.
3) State the requirement for pre-cleansing of the drainage system, either:
a) pre-cleansing not required (default); or
b) pre-cleansing is required; or
c) pre-cleansing required in some locations.
4) State the responsibility for clearing blockages, either:
a) survey the pipework run from the other direction, then proceed to remove the blockage by
cleansing (default); or
b) do not attempt to remove the blockage, then survey the pipework run from the other direction; or
c) move to an another location whilst the blockage is cleared by others as arranged by the
Overseeing Organisation's representative.
5) State the requirement for root cutting, either:
a) root cutting is required (default); or
b) root cutting is not required; or
c) root cutting may be required.
A3
Reporting requirements
A3.1
General
1) Detail any variation in the scope of the reporting requirements from that defined in this specification.
A3.2
Pipework and chambers defect survey by CCTV
1) State the requirement for a summary report in PDF format in addition to digital data, either:
a) summary report in PDF format is not required (default); or
b) summary report in PDF format is required.
2) State the requirement for CAD drawings in DXF and PDF formats in addition to digital data, either:
a) CAD drawings in DXF and PDF formats are not required (default); or
b) CAD drawings in DXF and PDF formats are required.
3) State the requirement for the survey data to be packaged with a proprietary software viewer, in
addition to the standard data deliverables, either:
a) survey data packaged with a proprietary viewer is required in addition to the standard data
deliverables (default); or
b) survey data packaged with a proprietary viewer is not required, only the standard data
deliverables are required.
4) State the requirement for items of the survey report to be provided to the Overseeing Organisation's
representative during the survey, either:
a) interim survey data is not required during the course of the survey (default); or
b) interim survey data is required during the course of the survey (details of required deliverables,
frequency and timing to be stated).
55
CS 551 Revision 0
Appendix A. Example schedule of requirements
5) State the means of transferring the data deliverable, either:
a) by internet transfer (default); or
b) by portable storage device; or
c) by DVD.
56
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Appendix B. Drainage condition grade quick assessment
B1
Introduction
This procedure provides a quick method of assessing the overall condition grade of highway drainage
assets without undertaking a detailed defect-level survey. It can be used for most drainage asset types,
both above and below ground, and is intended for use with the following:
1) all assets condition and connectivity survey;
2) priority asset survey;
3) filter drain condition assessment by GPR (structural condition only);
4) any other form of quick asset survey or inspection where a measure of current condition is required.
B2
Structural and service condition
Each drainage asset is visually assessed for both structural and service condition and a whole number
grade from 1 to 5 is assigned to each. In certain cases a grade of 9 or 0 may be assigned. The grades
are defined in CD 535 [Ref 1.N].
Where there are several defects of different types or severity in an asset, the most severe defect
determines the structural or service grade.
Where the inspection of an asset has been attempted, but it was not possible to assess the condition
(for example due to the asset being buried or otherwise obscured), a grade of 9 is assigned. Where it
has only been possible to inspect part of an asset, the grades reflect those parts that have been seen.
Where the unseen part could not be inspected because, for example, the pipe was blocked or the ditch
was severely overgrown with vegetation, then these defects are taken into account in assessing the
overall asset grades.
A grade of 0 is equivalent to no grade, indicating that assessment of the asset's condition has not been
attempted, for example because recording of that asset's condition is irrelevant (e.g. for ghost nodes),
or because the previously recorded asset could not be found in the field.
B3
Asset grouping
For the purposes of the quick assessment procedure, the various drainage asset types are grouped
together into assets of similar construction and function, as shown in Table B.1 below. The grouping
generally follows that of CD 535 [Ref 1.N], but with the following additional subdivisions:
1) chambers are split in to chambers and gullies;
2) ditches and channels are split in to four depending on whether their construction is hard or soft,
open or enclosed;
3) inlets and outlets are assessed using different criteria, depending on whether there is a formal
structure, such as a headwall, or not;
4) for combined surface and sub-surface filter drains the condition of the granular backfill medium and
the pipe are assessed separately and the worst grade is then reported for the asset.
The ancillaries group is a mixture of various asset types, some of which may occur either as a
standalone asset, or as an attribute of another asset, for example a flow control device within a
chamber or inlet/outlet. Where it occurs as part of another structure, then the condition grades relate to
the total structure, including the ancillary item. Pumping stations are a special case and require
specialist mechanical and electrical inspections that are beyond the scope of the quick assessment
method, which is limited to a high level assessment of whether there is deterioration of the structure
and whether the pumping station is performing (pumping water).
57
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.1 Grouping of drainage asset types for condition quick assessment
CD 535
Asset
group
Chambers
Inlets and
outlets
Asset subgroup for condition grade
quick assessment procedure
Chambers
Manhole, catchpit, inspection chamber,
rodding eye, soakaway chamber,
soakaway borehole, bifurcation or storm
overflow, lamphole, other special
chamber
Gullies
Gully
With formal structure
Outfall, inlet, outlet, grip inlet
Without formal structure
Outfall, inlet, outlet, grip inlet
Pipework, gravity drain, rising main,
culvert, syphon
Pipes
Combined surface and sub-surface filter
drain (pipe)
Combined surface and sub-surface filter
drain (filter media)
Filter drains
Ditches and
channels
B4
Included asset types
Counterfort drain, filter drain, soakaway
trench
Ditches
Ditch, grip
Enclosed channels
Combined kerb and drainage channel,
combined pipe and channel drain, linear
drainage channel
Open channels
Surface water channel, drainage channel
block, edge channel
Grassed channels
Grassed surface water channel or swale
Ponds
Detention basin, retention pond, sediment
pond, infiltration basin, pollution
containment pond or tank, wetlands, reed
bed treatment system, pond
(undifferentiated)
Ancillaries
Standalone flow control device,
interceptor, oil separator, pumping station
(overall structure and function), vortex
separator
Excluded assets
The drainage condition grade quick assessment method is not applicable to the asset types listed in
Table B.2 below, for one of the following reasons, and both structural and service grade of 0 should be
assigned:
1) the nature of the asset cannot be assessed without potentially destructive internal investigations;
2) specialist mechanical and electrical survey is required;
3) the asset type does not represent a physical asset.
58
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.2 Drainage asset types excluded from condition quick assessment
CD 535 Asset
group
Reason for exclusion
Pipes
Land drainage
Requires potentially destructive
internal investigations
Filter drains
Fin drain, narrow filter drain
Requires potentially destructive
internal investigations
Ditches and
channels
"Over the edge" drainage
No physical asset
Linear cellular storage system, reservoir
pavement
Requires potentially destructive
internal investigations
Pumping station (mechanical and electrical
aspects)
Requires specialist survey
Ghost node, phantom node, region node,
connector node, phantom connector, region
connector
No physical asset
Ancillaries
Drainage
network
modelling
B5
Excluded asset types
Condition grade quick assessment definitions and examples
The condition grade quick assessment of each asset is, to some degree, subjective and is based on
the experience of the inspector. To assist in standardising the assessments, asset-specific defect
definitions and photographic examples are given below. The examples are not exhaustive so in some
instances engineering judgement may be required to interpret the condition.
B5.1
Chambers
Chambers should be assessed in accordance with Table B.3 for structural condition and in accordance
with Table B.4 for service condition. The presence of manufactured holes in the chamber wall signifies
a soakaway, as could the presence of granular material within the chamber or no evidence of an
outgoing pipe.
59
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.3 Chambers - Structural condition grade quick assessment
Asset types
Structural
grade
Manhole, catchpit, inspection chamber, rodding eye, soakaway chamber,
soakaway borehole, bifurcation or storm overflow, lamphole, other special chamber
Example
Definition
No defects
1
No defects
Structurally sound, cover frame,
steps/ladder and safety chains where
required.
Any cracking limited to surface cracks.
Superficial defects
2
Superficial
defects
Individual crack.
Rocking cover.
Unpointed joint.
Minor defects
3
Minor defects
Multiple cracks.
Distortion.
Infiltration.
Loose frame.
Spalling of benching.
Unpointed lifting holes.
Major defects
4
Major defects
5
Not fit for
purpose or
unsafe
Multiple fractures.
Broken structure with sections missing.
Broken cover/frame.
Seized cover.
Loose or missing ladder support.
Void formed behind structure.
Complete collapse.
Missing cover/frame.
Loose or missing step/rung.
Loose or missing handrail.
Insecure or missing safety chain.
60
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.4 Chambers - Service condition grade quick assessment
Asset types
Service grade
Manhole, catchpit, inspection chamber, rodding eye, soakaway chamber,
soakaway borehole, bifurcation or storm overflow, lamphole, other special
chamber
Example
Definition
Clear
1
Clear
Unobstructed pipe/invert.
No sediment.
Superficial deposits with no loss
of performance
2
Superficial deposits with
no loss of performance
Sediment below invert of outgoing
pipe.
For chambers (other than catchpits)
sediment >5% cross-sectional area
(CSA) of pipe.
3
Performance slightly
reduced
Debris in channel invert.
Sediment filling catchpit sump.
For chambers (other than catchpits)
sediment 5-20% CSA of pipe.
No standing water.
Fine root penetration of structure.
4
Performance severely
reduced
For catchpits pipes partially blocked
<50% diameter.
For chambers (other than catchpits)
sediment 20-75% CSA of pipe.
Tap roots.
Soakaway part full of sediment.
5
Blocked or unsafe
condition
For catchpits sediment >50% pipe
diameter.
For chambers (other than catchpits)
sediment >75% CSA of pipe.
Root mass.
Soakaway full of sediment/water.
Oil contamination.
Performance slightly reduced
61
Performance severely reduced
Blocked or unsafe condition
CS 551 Revision 0
B5.2
Appendix B. Drainage condition grade quick assessment
Gullies
Gullies should be assessed in accordance with Table B.5 for structural condition and in accordance
with Table B.6 for service condition.
Table B.5 Gullies - Structural condition grade quick assessment
Asset types
Structural grade
Gully
Example
Definition
No defects
1
No defects
Intact pot, frame/grating
and brickwork.
Superficial defects
2
Superficial defects
Cracked pot.
Missing mortar/frame
bedding.
Missing stopper.
Minor defects
3
Minor defects
Fractured pot.
Fractured brickwork.
Cracked grating.
Grating >25mm below
surface.
62
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.5 Gullies - Structural condition grade quick assessment (continued)
Asset types
Gully
4
Major defects
Broken or leaking pot.
Broken brickwork or
missing brick.
Missing bar.
Failure of surrounding
pavement.
Grating 75–125mm from
channel edge.
5
Not fit for purpose
or unsafe
Collapsed pot.
Collapsed, broken or
missing grating.
Broken or missing frame.
Grating bars parallel to
road.
Grating >125mm from
channel edge.
63
Major defects
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.6 Gullies - Service condition grade quick assessment
Asset types
Service grade
Gully
Example
Definition
Clear
1
Clear
2
Superficial deposits with
no loss of performance
Clear pot, sump and grating
waterway.
Some sediment in sump.
Clear waterway water trap
maintained.
Performance slightly reduced
3
Performance slightly
reduced
Sump full of sediment but
water trap maintained.
Waterway partially
obstructed.
Performance severely reduced
4
Performance severely
reduced
Obstruction to flow, or
significant flow bypass.
Sump full of sediment with
blockage of waterway.
Thick layer of oil.
Blocked or unsafe condition
5
Blocked or unsafe
condition
B5.3
Complete blockage of flow or
flow bypasses grating.
Inlets and outlets (with formal structure)
Inlets and outlets (with formal structure) should be assessed in accordance with Table B.7 for structural
condition and in accordance with Table B.8 for service condition.
64
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.7 Inlets and outlets (with formal structure) - Structural condition grade quick
assessment
Asset types
Structural
grade
Outfall, inlet, outlet, grip inlet
Example
Definition
No defects
1
No defects
Handrail, path and harness eye present
where required for safe access.
No screen or an inclined screen with a
raking area.
Flow control operational where present.
2
Superficial
defects
Cracked mortar joints.
Loose concrete.
Minor defects
3
Minor defects
Cracked brickwork with no differential
movement.
Exposed reinforcement.
Vertical screen to outlet or deformed
screen.
Major defects
4
Major defects
Displaced bagwork or gabions.
Differential settlement.
Fractured structure (concrete or
brickwork).
Broken screen.
Flow control not operational.
Not fit for purpose or unsafe
5
Not fit for
purpose or
unsafe
Collapsed structure.
Handrail, path or harness eye absent
where required for safe access.
Screen present but missing handrails.
Vertical screen to inlet.
Table B.8 Inlets and outlets (with formal structure) - Service condition grade quick assessment
65
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Asset types
Outfall, inlet, outlet, grip inlet
Service grade
Definition
Example
Clear
1
Clear
Unobstructed screen/pipe.
Invert above channel bed.
Superficial deposits with no loss of
performance
2
Superficial deposits with
no loss of performance
Light debris on screen.
Pipe unobstructed.
Invert flush with channel
bed.
Performance slightly reduced
3
Performance slightly
reduced
Debris on screen causing
standing water in pipe.
Sediment depth in channel <
25% pipe diameter.
Performance severely reduced
4
Performance severely
reduced
Partially blocked screen with
obstruction of flow.
Sediment depth in channel 2
5–75% pipe diameter.
66
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.8 Inlets and outlets (with formal structure) - Service condition grade quick assessment
(continued)
Asset types
Outfall, inlet, outlet, grip inlet
Blocked or unsafe condition
5
Blocked or unsafe
condition
B5.4
Flow severely
impeded/surcharges.
Sediment depth in channel >
75% pipe diameter.
Inlets and outlets (without formal structure)
Inlets and outlets (without formal structure) should be assessed in accordance with Table B.9 for
structural condition and in accordance with Table B.10 for service condition.
67
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.9 Inlets and outlets (without formal structure) - Structural condition grade quick
assessment
Asset types
Structural
grade
Outfall, inlet, outlet, grip inlet
Example
Definition
No defects
1
No defects
Adequate handrail, fence, path and
harness eye present where required for
safe access.
No screen or inclined screen with raking
area.
Superficial defects
2
Superficial
defects
Settlement of piped outlet.
Minor defects
3
Minor defects
Pipe damaged.
Surrounding bank eroded.
Major defects
4
Major defects
Displaced pipes.
Differential pipe settlement.
Collapsing bank.
Not fit for purpose or unsafe
5
Not fit for
purpose or
unsafe
Collapsed pipe structure.
Loose pipes in channel.
Failure of bank.
Lack of adequate handrail, fence, path
or harness eye where required for safe
access.
68
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.10 Inlets and outlets (without formal structure) - Service condition grade quick
assessment
Asset types
Outfall, inlet, outlet, grip inlet
Service grade
Definition
Example
Clear
1
Clear
Unobstructed screen/pipe.
Invert above channel bed.
Superficial deposits with no loss of
performance
2
Superficial deposits with
no loss of performance
Light debris.
Pipe unobstructed.
Invert flush with channel
bed.
Performance slightly reduced
3
Performance slightly
reduced
Debris causing standing
water in pipe.
Sediment depth in channel <
25% pipe diameter.
Performance severely reduced
4
Performance severely
reduced
Flow obstructed.
Sediment depth in channel 2
5–75% pipe diameter.
69
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.10 Inlets and outlets (without formal structure) - Service condition grade quick
assessment (continued)
Asset types
Outfall, inlet, outlet, grip inlet
Blocked or unsafe condition
5
Blocked or unsafe
condition
B5.5
Flow severely impeded or
surcharges.
Sediment depth in channel >
75% pipe diameter.
Pipes
Pipes should be assessed in accordance with Table B.11 for structural condition and in accordance
with Table B.12 for service condition. Combined surface and subsurface filter drains are composed of
the granular backfill medium and the pipe; the condition of these two parts should be assessed
separately and the worst grade reported for the asset as a whole.
Table B.11 Pipes - Structural condition grade quick assessment
Asset types
Structural
grade
Pipework, gravity drain, rising main, culvert, syphon, combined surface and
sub-surface filter drain (pipe)
Example
Definition
No defects
1
No defects
Any cracking limited to surface cracks.
Plastic pipe deformation <5%
70
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.11 Pipes - Structural condition grade quick assessment (continued)
Asset types
Pipework, gravity drain, rising main, culvert, syphon, combined surface and
sub-surface filter drain (pipe)
Superficial defects
2
Superficial
defects
Circumferential or longitudinal crack.
Medium (estimated 1–1.5x pipe
thickness) open or displaced joint.
Slight wear or spalling.
Plastic pipe deformation 5–10%.
Evidence of previous repair.
Minor defects
3
Minor defects
Multiple or spiral cracks.
Circumferential or longitudinal fracture.
Deformation <5% (rigid) or 10–20%
(plastic).
Large (estimated >1.5x pipe thickness)
open or displaced joint.
Medium wear or spalling (e.g. visible
aggregate).
Puncture on inside wall (twin wall).
Major defects
4
Major defects
Multiple or spiral fractures or broken.
Deformation 5–10% (rigid) or 20–33%
(plastic).
Severe wear or spalling (e.g. missing
aggregate).
Split on inside wall (twin-wall).
71
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.11 Pipes - Structural condition grade quick assessment (continued)
Asset types
5
Not fit for
purpose or
unsafe
Pipework, gravity drain, rising main, culvert, syphon, combined surface and
sub-surface filter drain (pipe)
Already collapsed or broken with
deformation >10% (rigid) or >33%
(plastic).
Extensive missing fabric.
Split in inner and outer walls (twin-wall).
Reinforcement defective.
Defective connection.
Open joint or hole with visible soil or
void.
Defective repair.
Not fit for purpose or unsafe
Table B.12 Pipes - Service condition grade quick assessment
Asset types
Service grade
Pipework, gravity drain, rising main, culvert, syphon, combined surface
and sub-surface filter drain (pipe)
Example
Definition
Clear
1
Clear
Unobstructed (no impedance to
flow).
Superficial deposits with no loss
of performance
2
Superficial deposits with
no loss of performance
Fine roots, deposits or soil
ingress <5% of CSA.
Intruding lateral <5% diameter.
72
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.12 Pipes - Service condition grade quick assessment (continued)
Asset types
Pipework, gravity drain, rising main, culvert, syphon, combined surface
and sub-surface filter drain (pipe)
Performance slightly reduced
3
Performance slightly
reduced
Root mass <20% CSA, or
deposits or soil ingress 5–20%
CSA.
Intruding lateral 5–20% diameter.
Performance severely reduced
4
Performance severely
reduced
Tap roots or root mass 20–50%
CSA.
Scale deposits >20% CSA.
Sediment 20–75% diameter.
Intruding lateral 20–75%
diameter or hanging sealing ring.
Blocked or unsafe condition
5
Blocked or unsafe
condition
B5.6
Blockage/obstacle such as root
mass >50% CSA.
Debris/sediment deposits >75%
CSA.
Intruding lateral>75% diameter.
Filter drains
Filter drains should be assessed in accordance with Table B.13 for structural condition and in
accordance with Table B.14 for service condition. Combined surface and subsurface filter drains are
composed of the granular backfill medium and the pipe; the condition of these two parts should be
assessed separately and the worst grade reported for the asset as a whole.
Table B.13 Filter drains - Structural condition grade quick assessment
Asset types
Structural
grade
Counterfort drain, filter drain, soakaway trench, combined surface and sub-surface
filter drain (filter media)
Definition
73
Example
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.13 Filter drains - Structural condition grade quick assessment (continued)
Asset types
Counterfort drain, filter drain, soakaway trench, combined surface and sub-surface
filter drain (filter media)
No defects
1
No defects
Structurally sound.
Superficial defects
2
Superficial
defects
Individual stones displaced from filter
drain, with no visible deterioration of
filter drain itself.
Minor defects
3
Minor defects
Presence of wheel rut with scattered
medium.
Major defects
4
Major defects
Encroaching earthworks.
Surface obscured (not due to surface
treatment).
Inappropriate medium (Type A in
carriageway drain).
Multiple wheel ruts with major
displacement of medium onto
carriageway.
74
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.13 Filter drains - Structural condition grade quick assessment (continued)
Asset types
Counterfort drain, filter drain, soakaway trench, combined surface and sub-surface
filter drain (filter media)
Not fit for purpose or unsafe
5
Not fit for
purpose or
unsafe
Combined surface and sub surface filter
drain remote from pavement edge
(excludes toe drain).
Table B.14 Filter drains - Service condition grade quick assessment
Asset types
Service grade
Counterfort drain, filter drain, soakaway trench, combined surface and
sub-surface filter drain (filter media)
Example
Definition
Clear
1
Clear
Unobstructed clean filter
material.
Superficial deposits with no loss of
performance
2
Superficial deposits with
no loss of performance
Presence of surface sediment.
Sediment build up at pavement
edge.
75
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.14 Filter drains - Service condition grade quick assessment (continued)
Asset types
Counterfort drain, filter drain, soakaway trench, combined surface and
sub-surface filter drain (filter media)
Performance slightly reduced
3
Performance slightly
reduced
Vegetation established at
pavement edge (obstructs
inflow).
Vegetation established in
medium.
Performance severely reduced
4
Performance severely
reduced
Filter medium surface crusted.
Blocked or unsafe condition
5
Blocked or unsafe
condition
B5.7
Filter medium blocked such that
standing water is evident.
Ditches
Ditches should be assessed in accordance with Table B.15 for structural condition and in accordance
with Table B.16 for service condition.
Table B.15 Ditches - Structural condition grade quick assessment
Asset types
Structural
grade
Ditch, grip
Definition
76
Example
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.15 Ditches - Structural condition grade quick assessment (continued)
Asset types
Ditch, grip
No defects
1
No defects
Uniform channel cross section.
Superficial defects
2
Superficial
defects
No loss of channel section.
Minor disturbance exposing subsoil in
ditch side, e.g. evidence of burrowing.
Exposed lining at bank top or displaced
joints in lining.
Minor defects
3
Minor defects
Some loss of channel section due to
established burrows, side slope
instability or movement, with flow
slightly impeded.
Exposed non-concrete liner in channel
side or displaced concrete liner.
4
Major defects
Obstruction of channel due to significant
slippage of side slope, with flow
severely impeded.
Exposed non-concrete liner in channel
invert or torn liner above top water level.
Concrete liner broken, not blocking
channel.
77
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.15 Ditches - Structural condition grade quick assessment (continued)
Asset types
Ditch, grip
Not fit for purpose or unsafe
5
Not fit for
purpose or
unsafe
Complete blockage of channel due to
collapsed side slope or concrete liner.
Severe burrowing.
Flow dammed.
Liner ripped below top water level.
Table B.16 Ditches - Service condition grade quick assessment
Asset types
Service grade
Ditch, grip
Example
Definition
Clear
1
Clear
Short grass, no sediment or debris.
Superficial deposits with no loss
of performance
2
Superficial deposits with
no loss of performance
Some vegetation growth or
accumulation of debris in
channel, e.g. long grass / reeds,
litter.
3
Performance slightly
reduced
Pools forming in channel.
Channel obstructed by vegetation
(e.g. rushes), sediment banks
retaining standing water, shrubs
becoming established.
Significant debris e.g. individual
vehicle components, building
products.
Performance slightly reduced
78
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.16 Ditches - Service condition grade quick assessment (continued)
Asset types
Ditch, grip
Performance severely reduced
4
Performance severely
reduced
Significant loss of channel capacity
due to heavy sediment deposition,
saplings established.
Significant debris, e.g. multiple
vehicle components.
Blocked or unsafe condition
5
Blocked or unsafe
condition
B5.8
Channel full of sediment.
Outlets virtually or completely
blocked.
Mature trees.
Large items of debris, e.g. vehicle.
Enclosed channels
Enclosed channels should be assessed in accordance with Table B.17 for structural condition and in
accordance with Table B.18 for service condition.
79
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.17 Enclosed channels - Structural condition grade quick assessment
Asset types
Combined kerb and drainage channel, combined pipe and channel drain, linear
drainage channel
Structural
grade
Example
Definition
No defects
1
No defects
No defects.
Superficial defects
2
Superficial
defects
3
Minor defects
Chipped or weathered concrete.
Surface corrosion.
Cracked kerb-drain unit.
Cracked integral cover or
damaged removable cover.
Major defects
4
Major defects
5
Not fit for
purpose or
unsafe
Displaced unit.
Broken kerb-drain unit.
Broken integral cover or missing
removable cover.
Table B.18 Enclosed channels - Service condition grade quick assessment
80
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Asset types
Service grade
Combined kerb and drainage channel, combined pipe and channel drain,
linear drainage channel
Example
Definition
Clear
1
Clear
No sediment in channel.
Superficial deposits with no loss
of performance
2
Superficial deposits with
no loss of performance
Some sediment or vegetation, or
litter on channel grating.
Performance slightly reduced
3
Performance slightly
reduced
Channel partially obstructed by
debris.
Vegetation becoming established in
gratings.
Blocked waterway.
Performance severely reduced
4
Performance severely
reduced
Significant loss of channel capacity
due to heavy sediment deposition.
Waterways obstructed by debris.
Vegetation blocking some of the
grating slots.
Blocked or unsafe condition
5
Blocked or unsafe
condition
Channel full of sediment.
Waterways completely obstructed.
Grating/inlet blocked.
81
CS 551 Revision 0
B5.9
Appendix B. Drainage condition grade quick assessment
Open channels
Open channels should be assessed in accordance with Table B.19 for structural condition and in
accordance with Table B.20 for service condition.
82
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.19 Open channels - Structural condition grade quick assessment
Asset types
Surface water channel, drainage channel block, edge channel
Structural
grade
Example
Definition
No defects
1
No defects
No defects.
Superficial defects
2
Superficial
defects
Surface cracking or weathering.
Minor defects
3
Minor defects
Missing sealant at joint.
Major defects
4
Major defects
Displaced or misaligned units (pre-cast
concrete only) causing ponding.
Spalling concrete.
83
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.19 Open channels - Structural condition grade quick assessment (continued)
Asset types
5
Not fit for
purpose or
unsafe
Surface water channel, drainage channel block, edge channel
Fractured/broken.
Table B.20 Open channels - Service condition grade quick assessment
Asset types
Service grade
Surface water channel, drainage channel block, edge channel
Example
Definition
Clear
1
Clear
No sediment.
Superficial deposits with no loss
of performance
2
Superficial deposits with
no loss of performance
Some sediment or vegetation in
invert.
Litter in channel.
3
Performance slightly
reduced
Channel obstructed by debris,
vegetation or sediment causing
ponding in invert.
Performance severely reduced
B5.10
4
Performance severely
reduced
Significant loss of channel capacity
due to heavy sediment deposition.
Channel or gratings partially
obstructed by debris.
5
Blocked or unsafe
condition
Channel full of sediment or debris.
Gratings completely obstructed.
Grassed channels
Grassed channels should be assessed in accordance with Table B.21 for structural condition and in
accordance with Table B.22 for service condition.
Table B.21 Grassed channels - Structural condition grade quick assessment
84
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Asset types
Grassed surface water channel or swale
Structural
grade
Definition
Example
No defects
1
No defects
No defects.
2
Superficial
defects
Shallow wheel rut or depression at
channel edge with no impact on flow.
3
Minor defects
Shallow wheel rut within channel slightly
impeding flow.
Major defects
4
Major defects
Deep wheel rut severely impeding flow.
Exposed geogrid.
Not fit for purpose or unsafe
5
Not fit for
purpose or
unsafe
Multiple wheel ruts with displaced soil
forming ridge.
Flow dammed.
Exposed impermeable lining.
85
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.22 Grassed channels - Service condition grade quick assessment
Asset types
Service grade
Grassed surface water channel or swale
Example
Definition
Clear
1
Clear
2
Superficial deposits with
no loss of performance
3
Performance slightly
reduced
B5.11
No sediment.
Some sediment in invert or litter in
channel.
Channel obstructed by debris.
Intrusive vegetation or sediment
causing ponding in invert.
Raised grass edge strip forming.
Patches of bare ground.
4
Performance severely
reduced
Significant loss of channel capacity
due to heavy sediment deposition,
or channel or gratings partially
obstructed by debris.
Extensive bare ground.
Isolated damage to vegetation by
contamination.
5
Blocked or unsafe
condition
Channel full of sediment or debris,
or extensive vegetation blocking
flow.
Gratings completely obstructed.
Completely bare ground.
Extensive damage to vegetation by
contamination.
Performance severely reduced
Ponds
Ponds should be assessed in accordance with Table B.23 for structural condition and in accordance
with Table B.24 for service condition.
86
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.23 Ponds - Structural condition grade quick assessment
Asset types
Structural
grade
Detention basin, retention pond, sediment pond, infiltration basin, pollution
containment pond or tank, wetlands, reed bed treatment system, pond
(undifferentiated)
Example
Definition
No defects
1
No defects
Structurally sound.
Fencing secure.
Required warning signs present.
Good vehicle access to pond.
2
Superficial
defects
Disturbance of pond side slope.
Vehicular access difficult.
3
Minor defects
Evidence of burrowing.
Slope movement evident.
Liner visible in bank.
Vehicular access obstructed.
4
Major defects
Presence of large burrows in non
water-retaining slope.
Slope slippage.
Liner exposed and displaced in bank.
Security fencing insecure.
No constructed vehicular access to
pond.
5
Not fit for
purpose or
unsafe
Presence of burrows or slope slippage
in raised water-retaining slope.
Slope failure.
Liner torn/split.
No vehicular access to pond.
Lack of adequate security fencing,
missing lifebelt or other safety
equipment where required.
Pond has vertical sides with no means
of escape.
87
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.24 Ponds - Service condition grade quick assessment
Asset types
Service grade
Detention basin, retention pond, sediment pond, infiltration basin, pollution
containment pond or tank, wetlands, reed bed treatment system, pond
(undifferentiated)
Example
Definition
Clear
1
Clear
2
Superficial deposits with
no loss of performance
Clear of sediment and invasive
vegetation.
Flow into or out of pond not
impeded.
Sediment deposits visible.
Invasive vegetation established on
banks.
Performance slightly reduced
3
Performance slightly
reduced
Flow into or out of pond slightly
impeded.
Sediment levels <25% inlet or outlet
pipe diameter. Invasive vegetation
in pond.
4
Performance severely
reduced
Flow into or out of pond severely
impeded.
Pools formed due to sediment.
Sediment levels >25% inlet or outlet
pipe diameter.
Invasive shrubs in pond.
Blocked or unsafe condition
5
Blocked or unsafe
condition
B5.12
Flow into or out of pond blocked by
sediment.
Tree(s) in pond.
Ancillaries
Ancillaries should be assessed in accordance with Table B.25 for structural condition and in
accordance with Table B.26 for service condition.
Table B.25 Ancillaries - Structural condition grade quick assessment
88
CS 551 Revision 0
Asset types
Structural grade
Appendix B. Drainage condition grade quick assessment
Standalone flow control device, interceptor, oil separator, pumping station
(overall structure and function), vortex separator
Example
Definition
No defects
1
No defects
2
Superficial defects
No defects.
Rusty component.
Minor defects
3
Minor defects
Damaged baffle.
Structural crack.
89
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.25 Ancillaries - Structural condition grade quick assessment (continued)
Asset types
Standalone flow control device, interceptor, oil separator, pumping station
(overall structure and function), vortex separator
Major defects
4
Major defects
Loose flap valve, valve not
seating.
Missing vent pipe from oil
separator.
Missing weir sections.
Fracture.
Not fit for purpose or unsafe
5
Not fit for purpose
or unsafe
Seized or missing flap valve.
Missing handrail where
required for safety.
90
CS 551 Revision 0
Appendix B. Drainage condition grade quick assessment
Table B.26 Ancillaries - Service condition grade quick assessment
Asset types
Service grade
Standalone flow control device, interceptor, oil separator, pumping
station (overall structure and function), vortex separator
Example
Definition
Clear
1
Clear
Unobstructed with no impedance of
flow.
Superficial deposits with
no loss of performance
2
Superficial deposits with
no loss of performance
Minor accumulation of litter, sediment
or vegetation.
Performance slightly
reduced
3
Performance slightly
reduced
4
Performance severely
reduced
Flow slightly impeded due to litter,
sediment or vegetation.
Flow significantly impeded due to large
accumulations of litter, sediment or
vegetation.
Blocked or unsafe
condition
5
Blocked or unsafe
condition
Flow impeded causing surcharge.
Pollution risk.
Oil separator is full.
91
© Crown copyright 2019.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.
Design Manual for Roads and Bridges
Drainage
Inspection & Assessment
CS 551
England National Application Annex to CS 551
Drainage surveys
(formerly SD 15/03)
Revision 0
Summary
There are no specific requirements for Highways England supplementary or alternative to those
given in CS 551.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Highways England team. The email address for all enquiries and feedback is:
Standards_Enquiries@highwaysengland.co.uk
This is a controlled document.
CS 551 Revision 0
Contents
Contents
Release notes
2
1
CS 551 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Jun 2019
Highways England National Application Annex to CS 551.
2
© Crown copyright 2019.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.
Design Manual for Roads and Bridges
Drainage
Inspection & Assessment
CS 551
Northern Ireland National Application Annex to
CS 551 Drainage surveys
(formerly SD 15/03)
Revision 0
Summary
There are no specific requirements for Department for Infrastructure Northern Ireland
supplementary or alternative to those given in CS 551.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage of
this document to the dedicated team in the Department for Infrastructure, Northern Ireland. The email address for all
enquiries and feedback is: dcu@infrastructure-ni.gov.uk
This is a controlled document.
CS 551 Revision 0
Contents
Contents
Release notes
2
1
CS 551 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Jun 2019
Department for Infrastructure Northern Ireland National Application Annex to
CS 551.
2
© Crown copyright 2019.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.
Design Manual for Roads and Bridges
Drainage
Inspection & Assessment
CS 551
Scotland National Application Annex to CS
551 Drainage surveys
(formerly SD 15/03)
Revision 0
Summary
Please contact Transport Scotland for the application of CS 551. The email address is:
TSStandardsBranch@transport.gov.scot
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Transport Scotland team. The email address for all enquiries and feedback is:
TSStandardsBranch@transport.gov.scot
This is a controlled document.
CS 551 Revision 0
Contents
Contents
Release notes
2
1
CS 551 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Jun 2019
Transport Scotland National Application Annex to CS 551.
2
© Crown copyright 2019.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.
Design Manual for Roads and Bridges
Drainage
Inspection & Assessment
CS 551
Wales National Application Annex to CS 551
Drainage surveys
(formerly SD 15/03)
Revision 0
Summary
There are no specific requirements for Welsh Government supplementary or alternative to those
given in CS 551.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Welsh Government team. The email address for all enquiries and feedback is:
CustomerHelp@wales.gsi.gov.uk
This is a controlled document.
CS 551 Revision 0
Contents
Contents
Release notes
2
1
CS 551 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Jun 2019
Welsh Government National Application Annex to CS 551.
2
© Crown copyright 2019.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.