Firstly, we would never advocate undertaking excavation works without fully understanding as much as possible about the area in which you are about to dig. However, just because a utility survey is available, it is not necessarily the best or only option available to you.
Many companies now, particularly the larger ones have a procedure where the utility survey is a pre-requisite prior to any works being undertaken. This is a huge step forward for safety whilst excavating, but picking up the phone and booking in the survey is not necessarily the best course of action without the proper consultation being undertaken.
Firstly, under PAS128:2014 a survey comes in four different levels:
Type D – A desktop study where the available utility records are procured from asset owners and presented in a report or even CAD format.
Type C – This is a reconnaissance survey where the records and taken to site and the utilities are marked using above ground markers and features.
Type B – This is the location survey often referred to as a GPR survey. Geophysical techniques are used to locate services across the site.
Type A – Verification survey where trial holes excavation is undertaken to prove the results of a Type B survey.
Each of the above would be classed as a utility survey and to some extent each of the requirements of the previous level are included within the next, just the levels of detail and accuracy increase with the survey level. The automatic choice is generally the Type B as this is how it has always been done.
There are many factors which come into play when planning and undertaking a survey and these include the location, environment and specific site conditions.
For instance, if your site is in a rural location and the records indicate the area has no assets, the Type D survey may well be sufficient. Likewise, if you are working in critical areas of a city like London, you may well feel the need to go all the way to Type A to ensure the greatest level of detail.
Also, specific site conditions may come into play, particularly on larger sites where different types and levels of survey may be used for certain areas like where there are areas inaccessible for GPR due to site conditions.
Discussing these requirements with us prior to starting is always the best option then each party know the expected results from across the site at the start. Without the communication in advance, when the deliverables are received with areas missing due to specific restrictions or a large fee to survey an empty field, the relationship and trust between the surveyor and client suffers. This is not through either party being at fault, this is purely a communication issue which if resolved and the survey planning is collaborative, ensures all parties are happy with the final survey results.
Denmark Street is one of London's most famous streets. It has been a mecca for musicians for generations including artists such as Bob Dylan, The Sex Pistols and even Adele has performed there.
Mantra have recently been engaged to provide a utility survey for the area for the refurbishment of some of the listed buildings on the street. As usual in London the buried infrastructure was very congested and GPR also identified some buried structures in the buildings courtyard.
For the carriageway we employed an IDS Stream GPR system. This is towed behind a vehicle, minimising risk to surveyors and with it's as a multi frequency array provided very high resolution data for our Geophysicist to process.
We thoroughly enjoy the challenge of surveying in London and are now looking forward to the next one!
On 4th August a team from Mantra will be taking part in the Deepings raft race in Cambridgeshire.
We will be designing and building our own raft and entering the main race where the target is to set a fast time!
All this will be undertaken in aid of The Make a Wish foundation and we have set up a just giving page where people can pledge their support. The link can be found here.
We are hoping to raise as much as possible for this worthy cause, but one thing is for sure we are very likely to get wet and it will be a huge amount of fun.
This week our surveyors have been in Lancashire undertaking a services identification survey on a bridge.
This is an unusual undertaking because we can see the services we are identifying. Usually we need to identify them via geophysical methods.
For this project, access to the underside of the bridge had to be agreed with the port authority and network rail and we had access to a section of the underside of the bridge with a scaffold where we could measure and sketch the services and their locations and take photographs. For areas where we did not have scaffold access we had to rely on photographs taken from ground level.
On the surface, we then undertook a traditional utility survey using the usual methods of interrogating existing drawings, lifting and inspecting chambers and geophysical location.
This approach provided us with two sets of data which under comparison has allowed us to positively identify the contents of the ducts crossing under the bridge deck.
Over recent months we have found more requests for entering confined spaces as part of our utility survey works, as we already have personnel trained in the Level 2 City and Guilds Working in Medium Risk Confined Spaces (Water UK).
Based on our confined space entry experience, codes of practice and client requests, last week four members of the team completed the City and Guilds Level 3 Courses for Working in High Risk Confined Spaces and Emergency Rescue and Recovery of Casualties in a Confined Space.
This training provides an additional dimension to our utility survey skill set allowing us to be self-sufficient during an entry or offer the rescue team element to our clients undertaking entry to confined spaces structures for works not relevant to what we would normally be involved with.
The training was provided by Citrus Training at their Irthlingborough centre where the candidates passed the written exams and the intense and very physical practical exercises to complete the qualification.
Of course, we all hope that this is the kind of training which we never need to put into practice, but confined spaces can be dangerous and accompanied by regular drills and exercises, we can be sure that we have the necessary skills should we be called into action.
Project: London Stansted Airport – Various Projects
Works: Utility Mapping
Description: Mantra Services have been commissioned to undertake various PAS 128 utility mapping surveys in and around the vicinity of London Stansted Airport over a period of 2 years. These included a new exit plaza, development of the existing valet area and existing car park, airside water main alterations and National Air Traffic Systems around the control tower. Our client reiterated the importance of the highest level of accuracy. Fibre optic cables which serviced the airport with vital data were in abundance, therefore it was essential the information we provided our client was meticulously captured and post processed. The multi site nature of this project, with its heavily congested network of underground utilities posed a number of challenges that required the latest detection and post processing technology. However, despite the extremely high profile and high risk environment, Mantra services were able to exceed our client's expectations by providing the project deliverables with complete accuracy and to schedule.
Project: St James Square - Northampton
Works: Utility Mapping
Description Mantra Services were commissioned to undertake a utility survey for a very busy area St James area of Northampton. The survey area included covering the junction of the A4500 and A428, both very heavily trafficked roads into the town. The survey areas was approximately 27,000m2 The survey required the deployment of effective pedestrian and traffic management and some GPR data was collected using our bespoke GPR vehicle mounted system. Due to the very heavily trafficked roads some of the works were planned for the Easter weekend and some nights to ensure the safe and successful delivery of the project
Project: Fenchurch Street, City of London
Works: Utility Mapping Survey
Description Mantra Services were commissioned to undertake a PAS 128 survey in the vicinity of Fenchurch Street for the proposed demolition of a city block and subsequent £400million development of the project colloquially known as 'Gotham City'. After our initial reconnaissance we decided this project would require a PAS128:2014 survey level of M4P to successfully map the extremely complex underground network of pipes and cables. Due to nature of the location, we were unable to proceed with any work until permission had been granted for traffic management by the City of London. This required intense negotiation and effective communication to arrange dates and times which would create minimal disruption to this densely populated area. It was decided much of the work would need to be undertaken out of hours at nights or weekends. The post processing procedure involved using 3D GPR post processing to provide the most accurate information available for this high profile project.
Project: St Giles Street, Northampton
orks: Utility Mapping and 3D GPR Surveys
Description Mantra Services were commissioned to conduct a PAS 128 utility detection survey along side a 3D GPR survey, as our clients had concerns there may be basements and other obstructions underground. Using the latest technology and post processing available we were able to advise our clients of, not only a complex underground network of utility assets, but we were able to determine the location of reinforced buried structures which could have had a major impact on the outcome of the scheme if left unknown. Our client had split the project into two phases, therefore it was vital we maintained effective communication channels with our client in order to deliver the survey to their requirements.