Taking a pharmacy and aseptic suite build from start to finish, BES designed and delivered the project at Weston Park Hospital in Sheffield, UK. Engineering Director, Jonathan Morton, walks through the process
The newly created Inner Support Area
Weston Park Hospital, part of the Sheffield Teaching Hospitals NHS Foundation Trust, specialises in cancer treatment. The hospital is in the process of realising a two-phase refurbishment project designed, engineered and constructed by BES, to create a new Advanced Therapy Medicinal Product (ATMP) and Clinical Trials (CT) aseptic suite, along with a refurbished pharmacy Chemotherapy Aseptic Dispensing Unit.
ATMP denotes an extremely sophisticated field of emerging biopharmaceutical medicines, with preparations tailored to the specific requirements of individual patients. This includes regenerative medicine, personalised treatments and the development of nanomedicines using either a gene therapy medicinal product, a somatic cell therapy medicinal product, or a tissue-engineered product.
One of the key improvements was the relocation of the main corridor
The pharmacy and aseptic suite project is designed to futureproof the hospital's drug preparation capabilities on site.
Appointed as principal designer and principal contractor, BES has been responsible for maintaining BAU (business as usual) within the fully operational hospital during the two-phase project. Redundant office areas on the 6th floor will be refurbished to create the Chemotherapy Aseptic dispensing facility in phase 1 and the former pharmacy will be refurbished as the new aseptic suite with CT and ATMP preparation facilities.
Working with the hospital's user requirement specification (URS) and engaging with the estates team and senior pharmacist, BES took the concept design from RIBA Stage 2 to stage 4. It was clear that there were opportunities to make significant improvements to the design to generate cost, buildability and operational benefits.
One of the key improvements was the relocation of the main corridor. The BES team suggested that this be switched from the north side of the building to the south because this will enable key areas that need to be temperature controlled to be located where there is less solar gain. This change will reduce the cooling load required for the facility, simplifying the building services and reducing operational cost.
The new pharmacy aseptic suite is arranged from east to west, occupying the entire level of the building. Former nurses' accommodation on the 7th floor was earmarked for refurbishment as a plant room to serve the new facilities and this had to be put in place during phase one to enable the new pharmacy to become operational before construction work commences on phase 2.
Phase 1 began with demolition of internal walls
As part of the design development process, BES also had to verify that the existing slab was capable of supporting the loads required for the two air handling units (AHU) needed for the pharmacy and aseptic facility. As the existing slab was constructed using hollow terracotta panels, confirmation of the slab's load capabilities was required to establish whether a replacement slab would be needed.
This addition to the original scope was avoided with the use of a screed. Once the load-bearing issues with the 7th floor slab had been resolved, it remained clear that service penetrations through this unconventional slab would have to be small in size. This required a greater number of small ducts, adding to the challenges of the congested service void.
The facilities have been designed to HTM and GMP pharmaceutical requirements. Because ATMP is such a new area of biopharma preparation, the design development process also involved consultation with the MHRA (Medicines and Healthcare Regulatory Authority) to ensure compliance. Following a consultation with MHRA, the change areas were split to avoid any cross-contamination risk. MHRA also confirmed the viability of the design, ensuring that validation can be achieved without any issues following completion.
Phase 1 began with demolition of internal walls, allowing in natural light throughout the facilities with views to both the north and south thanks to vision panels. This will be transformational for pharmacy staff because some areas of the old pharmacy have no aspect to the outdoors.
The internal layout has been reconfigured. On entering the suite from the stair or lift lobby, there is a primary change area and locker room. From here staff will enter the facilities via the perimeter corridor on the south side, which leads to the unclassified outer support room at the far side of the facilities.
From here, pharmacy staff will enter the Grade D inner support room, via a grade D first stage change area. They can then access, two Grade C isolator rooms, via a Grade C second stage change area. To maintain compliance with the required cleanroom grades, the accommodation has been designed with a pressure cascade of highest pressure in the isolator rooms, lower pressure in the secondary change area and lowest pressure in the inner support room.
Phase 2 project has been fully designed and will begin construction when the pharmacy team move across to the new accommodation.
Access to the aseptic suite will be through the new pharmacy outer support room or the perimeter corridor. A corridor will run through the centre of the suite, with access to the CT preparation facilities on the north side of the building, and to the ATMP preparation area to the south.
A clog wash designed specifically for the facilities and the pharmacy team's gowning protocols will also be located in this area, as a change of footwear will be required each time a member of staff moves between a Grade D and Grade C area. Due to the number of clog changes and variation in foot size, a bespoke clog storage system has also been included.
The entrance to the ATMP facilities will be at the far end of the central corridor. The outer support room will be accessed first. From here, operatives must pass through a first stage Grade D change area before entering the Grade D inner support room. They must then prepare for access to the Grade C ATMP isolator room in a Grade C change area, before being able to enter. Each stage of travel through the ATMP areas is governed by inter-connecting air-lock doors that are controlled on a traffic light system, which enables only one door to open at any given time with a visual colour cue to indicate when the magnetic locking system can be opened.
An important element of the design process for the ATMP facilities was to understand the health and safety implications of working with potentially hazardous materials. Consequently, the airflow has been designed to minimise contamination risk, while ensuring that accidental spillages in the ATMP isolator room are contained.
Maintaining highest negative pressure in the second stage change room prevents any spillages in the isolator room from escaping to the inner support or first stage change areas, or even to the outer support area.
The CT areas will be accessed from the opposite end of the same central corridor, with a similar route through the outer support room to a Grade D first change area, then the Grade D inner support room. From here, operatives will enter the Grade C second change area, before accessing the Grade C isolator room. These facilities will also be built with a traffic-light managed airlock system between each controlled environment. Pressure regimes will be the same differentials as the new pharmacy.
The air handling provision will follow the model already constructed for the new pharmacy, with full fresh air supply via the AHUs and a HEPA-filtered air extract, along with individual HEPA-filtered exhausts for each isolator.
As there is a need for the hospital to retain a functioning pharmacy at all times, two air handling units with heat recovery have been installed as part of the phase 1 programme. The fresh air supply will serve both the classified cleanroom areas and the ancillary rooms, and HEPA filters will clean the extracted air before this is released into the atmosphere.
Local Extract Ventilation (LEV) exhaust systems have been designed into the facility where sporicidal and alcohol spraying occurs. The CT and ATMP Isolator room LEVs will be filtered through safe change HEPA units before being discharged to the atmosphere.
Exhaust systems are where sporicidal and alcohol spraying occur
Across all cleanroom-classified areas of the new Chemotherapy Aseptic Suite and CT/ATMP Aseptic facilities, there will be a strict temperature control and upper humidity limits tolerance. The Grade C areas are maintained at 19°C ±2°C whilst the Grade D rooms are maintained at 19.5°C ±1.5°C. Both areas are controlled with an upper limit of 55% relative humidity.
To ensure these conditions are met consistently, a new BMS has been installed specifically for the Chemotherapy Aseptic Suite and CT/ATMP Aseptic Facilities. This will constantly monitor temperature, humidity and the various air pressure cascades between the different room grades (C, D and CNC+). Temperature sensors installed in the return ductwork from each room will monitor the temperature of the air leaving the location, enabling automated temperature adjustments by the BMS.
In this way, the environment will consistently meet temperature and humidity parameters, regardless of occupancy levels, equipment use or outdoor temperatures.
Validation of the new facilities has been embedded in the project design and construction process from the outset. Design reviews commissioned by the Trust were documented to enable design qualification.
Further detailed documentation has also been compiled during the construction phase to ensure the Installation Qualification carried out by the Trust cross-references with the as-built information, detailed design and URS. The BES team is also responsible for commissioning the new facilities and ensuring accurate information is available for future maintenance or modifications.
The new Chemotherapy aseptic dispensing unit has now been completed without disruption to the normal working of the hospital. Construction will begin on the aseptic facility as soon as the old pharmacy has been vacated.