The works involved installing approximately 55–60 linear metres of new 225mm solid uPVC drainage pipe, constructing a soak away/ attenuation tank system and completing the associated excavation, groundworks and site reinstatement.
During the project, the team encountered several unexpected underground obstructions and site conditions. HIR adapted the drainage design and working methods to overcome these challenges, completing the required installation and reinstatement works.
Client: Howard Tenens
Location: South Ockendon, London
Project dates: 25 September – 16 October 2026
Services: Groundworks, civil engineering, drainage installation and contaminated material removal
Main works: 55–60 linear metres of 225mm uPVC drainage and a new soak away/ attenuation tank system
HIR Ltd was appointed to carry out a drainage installation and associated groundworks package at the client’s commercial site in South Ockendon.
The project required excavation and trenching, installation of a new drainage system, construction of a soakaway and reinstatement of the affected areas.
The work also involved investigating existing underground services and dealing with unexpected conditions discovered during excavation.
The works involved several key requirements:
As excavation progressed, the team discovered several conditions that were not apparent from the original site information.
Unidentified underground tank
An undocumented underground tank was discovered during excavation. As it was not shown on the original site drawings, the team had to carefully expose and assess the obstruction before adapting the planned drainage route.
Existing underground services
The project required excavation around existing electrical services, including specialist hand excavation in sensitive areas. Further investigation was also required to locate an existing gas pipe that was not identified within the inspection pit area.
Unexpected ground conditions
Different areas of the yard had varying surface finishes and construction layers. Some sections contained multiple layers, while others had different finishes, making excavation and planning more complicated.
Low-grade asbestos-contaminated material
Low-grade asbestos-contaminated material was encountered during the works. This required additional investigation and a pause while test results were awaited, with parts of the programme held up for approximately 24 hours.
Rather than allowing the unexpected discoveries to prevent progress, HIR took a practical and adaptable approach to completing the groundworks package.
Following the discovery of the underground tank, the team carefully assessed the obstruction and redesigned the drainage alignment to divert around it. This allowed the installation to continue without disturbing the existing structure unnecessarily.
Additional investigation and specialist hand excavation were carried out around existing services, while the contaminated material was managed through the appropriate handling and disposal procedures.
HIR also adapted its excavation methods to account for the varying ground conditions encountered across the yard.
The main elements of the solution included:
Throughout the project, the focus remained on finding practical solutions, managing the changing site conditions and completing the required works.
HIR Ltd delivered a comprehensive package of drainage installation and commercial groundworks, including:
HIR Ltd successfully delivered the drainage and groundworks package, overcoming unforeseen underground obstructions, existing service constraints and unexpected ground conditions.
The revised drainage route allowed the installation to proceed around the previously undocumented underground tank, while the associated excavation, soakaway construction and reinstatement works were completed.
The reinforced concrete slab was reinstated and the final tarmac resurfacing completed, leaving the affected areas clean, safe and ready for use.
The project demonstrated HIR’s ability to adapt to changing site conditions and deliver practical groundworks and civil engineering solutions within a live commercial environment.
HIR Ltd provides commercial and industrial groundworks, civil engineering, drainage installation and site clearance services across London, Heathrow, Surrey, Berkshire and the wider UK.
From drainage installations and excavation to complex site works and reinstatement, our team works with commercial clients and contractors to deliver practical solutions tailored to each project.
If you require commercial groundworks, drainage installation or civil engineering support, contact HIR Ltd to discuss your requirements.
Telephone: 0208 166 1221
Email: info@hirltd.co.uk
Website: https://hirltd.co.uk/
