PAS128 Utility Mapping & avoiding risks in below ground engineering

John Robinson

Director, Malcolm Hugh Land Surveyors

HSG 47 Guidance Notes

Best available records

Why carry out a Utility Detection survey?

▪ Existing records are often inaccurate/incomplete.

▪ Risks extremely difficult to manage.

UTILITY LOCATION

ACCORDING TO STATS RECORD

ACTUAL LOCATION OF

UTILITY FOUND WITH

DESIGNATION (SURVEYED)

From simple surveying, to national

specification

PAS 128

Common Myths about Utility Detection, Verification & Location

• “RADAR” SURVEY

• “CAT” Survey

• Produces an “X-RAY” of the ground• Locates everything buried in the ground

• Identifies the different types of services buried

• Penetrates through all materials

• No need for statutory utility records - “Cheating”

• No need for up to date topographic survey- “OS will do”

• Can be done “the day before we break ground”

• TIME TEAM “Geophys”

Desktop Utility Record Search

Survey Type D

Site ReconnaissaneSurvey Type C

Detection Survey Type B

Verification Survey Type A

PAS 128 Quality Levels

Risk Assessment

Combination of

• Severity and Likelihood

• Consequence and Probability

• Impact and chance of occurrence

• Usually assessed using a matrix approach

Table 1 – Quality level designation of survey outputs

Survey category Quality level designation

Criteria used in the determination of quality level

Desktop utility record search

QL-D Information provided by a utility record search only

(No detection possible)

Site reconnaissance QL-C A segment of utility whose position is confirmed by visual reference to street furniture, topographical features or evidence of previous street works (reinstatement scar).(No detection possible)

Detection QL–B4 A utility segment which is suspected to exist but has not been detected and is

therefore shown as an assumed route.

(No detection possible)

QL-B3 Position of the utility detected by one of the geophysical techniques.

(EML OR GPR detection with limited confidence in depth)

QL-B2 Position and depth of the utility detected by one of the geophysical

techniques.

(EML OR GPR detection with confident depth)

QL-B1 Position and depth of the utility detected by multiple geophysical techniques.

(EML + GPR detection)

Verification QL-A Horizontal and vertical position of the top and/or bottom of the utility.

Additional attribution is recorded as specified in PAS128

(Utility exposed – trial pit, IC, MH etc.)

ALL ICs/MHs where utility is confirmed Only denote where utility cannot be verified at ICs/ MHs

e.g. flooded chamber/No Pipes Visible

Comment left on HSE website

• In my personal opinion… with >30 years experience … I think that there must beat least 100's of incidents per day of which only a tiny minority are reported

Comment left on HSE website

• One contractor I know has hit 5 service connections TODAY in ONE street - 1 gas service and 5 electric!!

• If the gas hasn't ignited, or isn't very big, there is no RIDDOR for any of these!!

• Apparently it's like a war zone down there!!

Comment left on HSE website

• Try the Energy Networks Association. They collate national statistics (although I'm not sure whether they will release them).

• From memory, there are around 25,000 reports quoting third party damage as the cause, per year.

• The vast majority (more than 22,000) are low voltage cables.

Case Studies - HSE website

• A labourer received burns to his torso and arm when he damaged a 415 volt electrical supply.– Employer fined £10,000

• A 17 year old was severely injured when he struck an underground cable using a pneumatic breaker.– Employer fined £40,000

• A worker suffered deep burns after he hit an 11,000 volt cable when excavating using a road breaker– fined the maximum for this offence after the magistrate decided not to pass

the case up to Crown Court.

– The injured worker awarded compensation and HSE awarded costs in full.

• A 42 year old labourer was burned and died in hospital 9 days after hitting an 11,000 volt cable.– Employer fined £50,000

https://www.youtube.com/watch?v=1L9aE2Gsn0k

PAS 128 Launch Event: End user prospective by Andy Rhoades

Estimated TOTAL Cost World wide : £13 Billion

The benefits

Tendering based on PAS 128 will

Provide More Control to the client

• Fair competition

• Better bid evaluation

• Consistent service

• Agreed level of accuracy for geospatial

Analysis/BIM models

• Improved risk management

• Improved safety- planning/execution of street works, ground works and utility based activities

• Raised industry standards

• Reduced construction costs

• How much does a broken or damaged utility cost???

• Answer is about £1000.

• However this does not take into account down time, construction delays, costly redesigns, H&S issues and 3rd party costs/claims.

• The real cost is as much as 29 times

• 29 X £1000=£29000!!! Research by University of Birmingham

The benefits

• Will it make the project safer– NO ! But you can.– By understanding application and limitations– Best available technology applied in a best practice

methodology– Best available data– Informed risk decision making as part of SUE

• Design• Planning• Demolition• Construction• Maintenance

H&S benefits of PAS128?

Questions