Underground Mapping 450m of Birmingham Sewers

Underground Mapping 450m of Birmingham Sewers

About This Project

St Joseph Homes Limited, part of the Berkeley Group, one of the leading property developers across London, Birmingham and the South of England, is currently undertaking a large development in Birmingham City Centre. The project required a full underground utility survey to locate the position of a complex underground sewer network 15m below the streets of Birmingham. Previous records showed that the old sewer, 1500mm in diameter, was running in close proximity to their site. The underground utility survey would provide the developer with critical data that will help them in their design process to correctly position pile foundations and minimise risk of damage and disruption to the daily functioning of the working sewer.


Due to the confined space and size of the sewers, access was highly restricted. The team at St Joseph needed a specialist company with substantial knowledge of underground assets to safely and quickly access the high risk confined space to collect the survey data. So it turned to the team at Murphy Surveys to provide the knowledge and expertise to deliver the survey.


Site investigation work was carried out prior to the start of the project to establish if the sewer was safe and structurally sound, as well as to understand the number of working access points available. This was critical to determine the best method to collect the data and to ensure all health and safety aspects were recorded and carefully considered to minimise risk.


The site required a traverse in excess of 450m, the biggest traverse Murphy Surveys have undertaken, with a requirement of 25 operatives including high risk confined space rescue teams, each performing their own individual task using confined space entry equipment. Extensive risk assessments and method statements described in detail every operative’s position and role during the traverse in order to maintain the highest standards of safety.


The team used the Leica P40 laser scanner and lightweight tripod to capture the data. Control was established above ground and a topographical drawing was created from the scan data. Each manhole was scanned with the P40 from the surface, using an inverted tripod over the 3 landings. Each landing was scanned individually allowing the team to link the surface data with the subsurface map.


Due to the cylindrical nature of the sewer, Murphy Surveys researched and developed its own supporting bracket for several of the targets, which were used to link the scans through the sewer. The unique bracket was designed to sit just above the water line to prevent being washed away in the fast flow of the water.


Traffic management was arranged for safe access to the site and the egress to the confined space and to protect the public.


The project was completed on time and to budget with all 25 operatives working together to capture the data quickly and safely.


“The network of sewers some 15 meters below ground 1500mm diameter, meant we were working in an extremely confined environment, with the added challenge of the changing water levels,” commented Andy Gundry, Subsurface Mapping Manager, Murphy Surveys. “Planning was critical to ensure the safe delivery of this project, collaborating with the client, the asset owner and the specialist team to minimise the risk involved with such a hazardous high risk location.”


“The resulting data was delivered to St Joseph’s via a 2D topographical drawing of the sewer system mapped underground in relation to above ground features and more importantly mapped to the client’s construction works. Providing St Joseph with invaluable data to support their design process and ensure the safe positioning of pilling and construction work without affecting the daily operation of the public sewer. In addition, the resulting utility map has given the asset owner peace of mind that the sewer would continue to function without any costly delays or disruption in its service.”


Jamie Cooper, Project Director, St Joseph Homes Limited commented: “I can’t thank you enough for your efforts planning and managing the works over the past weeks, attending meeting and revising RAMS to ensure all was professional, clear and safe for the onsite activities. Many, many thanks!



Murphy Surveys St Joseph Homes


St Joseph Homes Limited part of The Berkeley Group of property developers.



Survey Type

Subsurface Mapping


• High Risk Confined Space Rescue Teams and confined space entry equipment
• Leica P40 Laser Scanner and associated targets


Subsurface Mapping