HMP Chelmsford

Client: Galliford Try
Contract Value: Circa £2.5m
Duration: 12 months

Project Description

EJT63 delivered a significant infrastructure upgrade for Galliford Try and the Ministry of Justice. The project involved the installation of over 1250 metres of new 450mm diameter gas main across the prison estate, including 750 metres of laterals terminating at the existing buildings.

Because of the scale of the pipework and the nature of the site, our scope included a full enabling works package. We constructed a dedicated site compound and haul road to manage the logistics of the project, alongside the installation of reinforced concrete bases for new storage containers and a generator. A key part of scheme involved structural work to the prison’s external boundary wall and internal secure fencing to allow the new main to pass through safely.

More about the scheme

• Operating inside a Category B prison required a logistical approach that respected the facility’s security above all else. Our site team embedded themselves into the daily routine, learning the HMP schedule to ensure our work never clashed with internal operations. Before starting on-site, we coordinated a full methodology with Galliford Try and the MoJ to guarantee the project could proceed without disrupting the regime. This allowed us to manage high-impact tasks, like excavations and material deliveries, strictly within the windows provided by ‘mass moves’ and escort availability.
• The proposed route for the gas main was heavily congested with live services, demanding specialist routing and coordination. To mitigate risk, we employed a data-led approach using PAS128 surveying and targeted trial holes. This intelligence enabled our team to anticipate utility clashes early, allowing us to realign the main using carefully selected bends to ensure a seamless installation
• Dating back to 1825, HMP Chelmsford presented significant challenges due to a lack of accurate historic as-built records. To navigate this, we carried out extensive trial hole investigations to understand the specific construction details before passing the gas main through the external boundary walls. Our team used precision coring and installed a new lintel system to protect the wall’s structural integrity, ensuring the gas main entered the building exactly as designed. We adopted this methodical approach for every structural penetration across the prison to maintain consistency and safety