Underground Drainage Tracing and Utility Mapping at Selhurst Station
WRC-approved drainage condition reporting, underground drainage tracing and site mapping delivered over three night shifts at Selhurst Railway Station, supporting planned construction works for a main contractor.
Location: Selhurst, London
Service: Drain tracing and mapping
Overview
We were appointed to support underground services investigation works around Selhurst Railway Station in London ahead of planned construction activity being delivered by a main contractor.
The project required accurate tracing, mapping and condition assessment of surface water and foul water drainage assets within the carriageway. This information was needed to help inform the safe planning of construction works at the station, including the siting of a crane.
The survey area was located on a busy T-junction with a steady flow of traffic, so the works were carried out under traffic management over three night shifts. This allowed our team to complete the drainage investigation safely while minimising disruption to the surrounding road network and local businesses.
Alongside our drainage survey works, we also supported UTSS Limited with Ground Penetrating Radar, also known as GPR, to help identify additional underground utilities once the drainage tracing had been completed.
What we did
Our team carried out a detailed drainage tracing, mapping and condition assessment exercise across the required section of carriageway. The drainage lines were suitable for push rod camera surveying, with pipework recorded at approximately 225mm diameter. We used a push rod CCTV drainage camera together with a sonde locator above ground to trace the route of the drainage lines.
At each metre of the line, the sonde location was marked at surface level. This allowed the surveyor to capture accurate GPS positions and build a reliable mapped record of the drainage route. The works included:
Identifying and accessing surface water and foul water drainage assets
Surveying 225mm drainage lines using a push rod CCTV camera, whilst tracing the route using a sonde locator from above ground
Recording invert levels and cover levels across the site
Completing a full drainage condition assessment
Producing a WRC-approved drainage survey report including mapping information to support UTSS in creating an accurate technical CAD drawing
The drainage condition assessment identified a number of existing defects within the network. Recording these defects before construction activity began gave the main contractor a clear baseline record of the drainage condition ahead of the works. This is particularly important on infrastructure and construction projects, where pre-condition evidence can help protect contractors and clients if damage claims are raised after the works have been completed.
The outcome
The full survey area was completed successfully over three night shifts, with all required drainage tracing, mapping and condition assessment works delivered within the traffic management window.
Following completion on site, we produced a WRC-approved drainage survey report within three working days. The report included full condition assessment information, drainage mapping, invert levels and cover levels, enabling UTSS Limited to prepare an accurate technical CAD drawing for the wider project team.
The identification of pre-existing drainage defects provided the main contractor with valuable evidence ahead of the construction phase. This helped establish the condition of the drainage network before works began and gave the contractor supporting information should any future damage claims arise.
This was a great infrastructure project to be involved in. It allowed us to support a time-critical station construction programme, work closely with UTSS Limited, and gain additional experience assisting with GPR utility detection activities.
Location
The project was carried out around Selhurst Railway Station in London.
We provide drain tracing and drainage mapping surveys for contractors, developers and infrastructure teams across the UK, helping identify the location, route, depth and condition of underground drainage assets ahead of construction works.
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