Topographical & utility Survey of 150,000 m2 site
We were instructed to carry out a utility and topographical survey a de-commissioned UK Prison, previously a male juvenile’s prison and Young Offenders Institution.
The prison closed in 2017, following an announcement at the end of 2016 that it would be replaced with a newly built category C adult prison. The prison is to be demolished and redeveloped with a new prison built in its place.
The overall aim of the project was to provide an accurate CAD plan of the entire site above and below ground. To achieve this a topographical and utility survey was required to fully map all the assets above and below the ground. In summary we surveyed:
- Size of site = 150,000 m2
- 600+ Manholes surveyed and traced
- 40+ Buildings
- 2km Road
- 10km’s of underground utilities
- PAS128 level B compliant
The sheer size of the site was the main challenge, so ensuring the right data capture method was critical to bring the project in on-time, within budget and at the right accuracy.
To achieve this, multiple data capture methods were used. These are the latest technological advancements in the geospatial industry bringing multiple benefits. These included:
- Lecia Pegasus: TWO mobile mapping – This was used to map all the large areas and roads, safely, quickly and accurately.
- Stream C: Ground Penetrating Radar (GPR) – this is a compact array solution for real-time 3D mapping of underground utilities and features. The Massive array of 34 antennas in two polarisations can create accurate 3D reconstruction of the underground utility network in a single scan.
Alongside this a control network was accurately established which would last the duration of the project. These were installed on-site and offsite using GNSS and robotic total stations, along with images and witness diagrams for easy location in the future.
The whole site was surveyed above and below in 3 weeks. The data was processed, checked and verified with a total turnaround of 5 weeks providing to the client the following:
- 3D Topographic and Utility Plan (DWG)
- Revit topographic and utility model
- Manhole Schedule
Benefits of rapid data capture – LeanGeomatics
By using these methods of reality capture, very tight deadlines were achieved, and money was saved, without compromise. The client was very happy indeed, with further work anticipated.
#LeanGeomatics is term to ensure the client gets value for money, by making data capture and work flows as efficient as possible. By using the innovation, technology and workflows described in this case study, our clients are getting the best services available. Saving time onsite, bringing the delivery date forward and often being able to mobilise quicker by removing something for example, Traffic Management. This also has a positive impact on costs by reducing indirect spend.
Utility detection using GPR
Ground Penetrating Radar (GPR) is a sophisticated tool in the detection of buried services. With the advancement of technology and GPR arrays such as the IDS Stream C on the market, we can see below the ground better than ever before. However, expert interpretation is key, as you can see in the data images below. Severn Partnership are one of the only companies in the UK, not only offering this service, but ‘post processing’ the data. This ensures an accurate complete PAS128 compliant survey, giving confidence in what is buried and where.
Large projects = Lots of contractors
One benefit of the technology we use, and our experience, is the ability to work alongside other ongoing works and multiple contractors. The survey methods are non-intrusive and passive by nature ensuring minimal disruption even on the busiest of sites.
Make use of our expertise and avoid problems
While the teams were surveying onsite as you can see in the image below, a contractor on-site hit a water main. This could have been avoided if a survey had been done prior to any ground was broken and more importantly this data was then shared. Ironically, the survey team had the tools to be able to detect the water pipe prior to the bore hole being drilled by the contractor, which would have prevented this.