Build Over Drainage Survey in Stoke-on-Trent
Pre-build and post-build over CCTV drainage surveys carried out at a residential property in Stoke-on-Trent, helping the client obtain sign-off from the local water authority, Severn Trent.
We completed the initial pre-build survey before the extension works began, then returned after construction to confirm the condition and integrity of the existing shared drainage system and newly installed drainage infrastructure.
Location: Stoke-on-Trent, Staffordshire
Service: Build over drain survey
Overview
We were instructed to carry out a build over drainage survey at a residential property in Stoke-on-Trent, where the client was completing extension works over or near an existing shared foul drainage line.
For build over projects, water authorities often require a CCTV drainage survey before and after construction. The pre-build survey records the condition of the existing drainage system before works begin, while the post-build survey confirms whether the works have affected the drainage network and whether any new drainage has been installed correctly.
On this project, we completed both stages of the process. The initial survey provided a baseline record of the existing shared drainage system before construction. Once the extension works were complete, we revisited the property to carry out the post-build over CCTV drainage survey required to support final sign-off from Severn Trent.
What we did
The post-build over CCTV drainage survey was carried out using a push rod CCTV camera system to inspect all relevant sections of the drainage network.
Access was gained via:
MH1 and MH2, located on the neighbouring property
The newly installed IC1
The newly installed IC2 serving the extension drainage
As part of the completed extension works, two new inspection chambers had been installed. IC1 was constructed on the existing shared foul drainage line, providing access to the shared network. IC2 was installed to receive the internal foul drainage from the extension before connecting into the existing drainage network via IC1.
The purpose of the post-build survey was to:
Inspect the existing shared foul drainage line
Confirm the new inspection chambers had been installed correctly
Confirm the new extension drainage was connected appropriately
Check that the drainage system was functioning as intended
Compare the post-build condition against the original pre-build CCTV survey
Identify whether any defects had worsened following construction
Provide evidence to support water authority sign-off
The newly installed drainage infrastructure was found to be appropriately connected and functioning as intended at the time of the survey.
Outcome
The post-build over drainage survey confirmed that the completed drainage works had been installed correctly and that the new drainage infrastructure was operating as intended. The existing shared drainage system continued to show a similar level of deterioration to that recorded during the original pre-build CCTV drainage survey. Displaced joints and cracked sections of pipework remained present within the existing line, but no significant progression of these defects was observed following completion of the building works.
This was an important finding for the client, as the post-build survey provided evidence that the construction works had not adversely affected the existing shared drainage system beyond the pre-existing defects already recorded before the build began. Although the drainage system remained operational, the existing structural defects should still be addressed to prevent further deterioration over time. We recommended that the local water authority be notified of the defects identified in both the pre-build and post-build surveys.
Overall, the survey supported the client’s build over sign-off process with Severn Trent by confirming that the new drainage works had been installed correctly and that no evidence was found to suggest the extension works had worsened the condition of the existing shared drainage system. This project is a strong example of why pre-build and post-build over drainage surveys are important. They protect homeowners, contractors and water authorities by providing a clear record of drainage condition before and after construction works.
Location
This project was carried out at a residential property in Stoke-on-Trent, Staffordshire, as part of a build over agreement for a completed extension.
We regularly undertake pre-build and post-build over CCTV drainage surveys across Stoke-on-Trent, Newcastle-under-Lyme, Staffordshire and the surrounding areas, helping homeowners, architects and contractors obtain water authority approval and sign-off from providers such as Severn Trent.
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Helpful build over guidance
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