Unlocking Site Constraints and Civil Design for a New Hospital Urgent Treatment Centre

Project Overview.

• Project Name: SASH UTC, East Surrey Hospital, RH1 5RH

• Project Type: Healthcare Infrastructure (£8.6m Urgent Treatment Centre)

• Client: Surrey and Sussex Healthcare NHS Trust (SASH)

• Key Services: Enabling Works Design, Flood Risk Assessment (FRA), Sustainable Drainage Systems (SuDS) Design, BREEAM Compliance, Highway & Utility Diversion Design

The Challenge.

The development of a new two-storey Urgent Treatment Centre (UTC) at East Surrey Hospital presented immediate spatial and logistical constraints. The footprint of the proposed building directly conflicted with the hospital's existing Accessible Car Park, requiring a rapid enabling works solution before main construction could begin.

Furthermore, the initial project brief limited civil engineering intervention strictly to the area immediately surrounding the new building footprint, leaving the adjacent southern bus station and main hospital access roads unchanged. However, EPN Consultants’ initial level analysis and site sections revealed a critical design flaw: tying the building’s Finished Floor Level (FFL) into the existing north-eastern topography would result in an impracticable and unsafe 1:5 cross fall gradient for the southern footpaths. The project required a comprehensive, site-wide civil redesign to ensure accessibility, accommodate continuous bus transit and highway movements, and manage complex surface water infrastructure on a highly restricted brownfield site.

The Strategy.

Rather than working within the flawed constraints of the initial brief, EPN Consultants took a proactive approach to optimize the site layout, enhance buildability, and reduce attenuation costs.

Our strategy focused on three key areas:

• Scope Extension for Level Optimization: We demonstrated to the client that extending the design boundary south into the existing bus station and hospital entrance would not only resolve the impracticable footpath gradients but also unlock vital space for a centralized open SuDS feature.

• Value Engineering the Drainage Strategy: The initial site design relied on a third-party Flood Risk Assessment (FRA) that conservatively applied strict greenfield discharge rates to this brownfield site. Recognizing that greenfield parameters demanded unfeasible amounts of attenuation space on a tight hospital campus, we advised the client to allow EPN to draft a new, site-specific FRA based on realistic brownfield criteria, reducing required storage volumes and saving substantial space and cost, whilst remaining compliant with NPPF and CIRIA requirements.

• Regulator & BREEAM Alignment: We pivoted the secondary design iteration to strictly align with BREEAM POL 03 requirements, targeting absolute compliance across Flood Resilience, Surface Water Run-off, and Minimising Watercourse Pollution.

The Execution & Technical Solution.

With the broader strategy approved by the Trust, EPN Consultants executed the design across two distinct, highly coordinated phases:

1. Enabling Works & Car Park Relocation

   To clear the UTC footprint, we designed the relocation of the Accessible Car Park across Canada Avenue. We segregated the new accessible bays from the main parking area by researching and specifying off-the-shelf ARMCO barrier details, delivering full construction and safety specifications to ensure rapid site clearance for the incoming main contractors.

2. Advanced Civil & SuDS Infrastructure Design

   Upon receiving the architect's revised layout drafts, we conducted a rigorous impact assessment on existing underground utilities in collaboration with the M&E engineers, mapping vital service diversions and specifying the redundant lines. We simultaneously optimized the external works layout by correcting the road alignment to standard kerb radii to ensure long-term buildability for heavy bus traffic, and specified an appropriately durable asphalt mix for the busy turning head.

   To resolve the site's intense space restrictions, we transformed the central green island into a functional, compact SuDS attenuation basin. We executed complex hydraulic calculations to integrate the new, optimized brownfield discharge rate with the basin's geometry, flawlessly balancing the site's levels to feed the drainage network naturally.

The Result & Impact.

• Critical Access and Connectivity Secured: By identifying that the initial 1:5 gradient would render the southern footpaths entirely impracticable and cut off access to the bus stop, EPN's strategic expansion of the design area successfully unlocked a compliant design. This enabled flawless connectivity on the south side of the building, including direct, accessible passage between the UTC and the bus stop.

• Space & Cost Savings Realized: By replacing the conservative third-party FRA with an EPN-drafted assessment, we significantly reduced the required on-site storm water attenuation volume, protecting the client's budget and maximizing the available site footprint.

• BREEAM Compliance Secured: Delivered a comprehensive BREEAM Technical Note alongside fully integrated hydraulic calculations and level designs, ensuring seamless compliance with all POL 03 environmental requirements prior to planning submission.