Legionella Prevention Works and System Improvements at MHRA Facilities

MHRA general report for legionella works Surveys of each area are not conclusive as some areas are restricted. No access to rooms - 6120, 6023, 6046 - A sum will be allowed by the Client to cover the works for the rooms that were not accessible. Inspection of laboratories were carried out and issues logged where access behind cabinets and benches was available.

When works being carried out the contractor and building contractor to be on hand to move cabinets etc. When working in riser cupboards access to affected laboratories will be required to remove any identified issues, make sure all are rectified and outlets can be pulled through to flush, allow contingency sum for unidentified dead legs and toilet and cleaners cupboard areas.

Regarding low temperature of hot water service, we would recommend installing a circulating pump on flow with a checked bypass to increase flow. Descaling of outlets, fire stopping and making good etc by building contractor to be provided by the Mechanical contractor.

Some services should be taken back to main service pipe in corridors but due to additional works by other contractors they are inaccessible due to cable trays etc. IT Cabling could be an issue to remove. All works listed on survey sheets presume local isolation valves operate and will isolate. Some of the works require complete shutdown of North or South blocks so would need to be out of working hours.

Due to the nature and disruption in corridors and laboratories, we would suggest works are carried out weekends. Outlets with minimal usage will need to be surveyed if they are not to be flushed through on a regularly. A good percentage of outlets are not used very often, and a small amount is only drawn off; this does not flush system fully so a program of flushing weekly should be adopted.

Allow contingency sum for unidentified issues as they arise when works being carried out. Suggestions for bringing up to specification. Regarding new boosted water dead legs in north block are these to be used in future, if so and to remain then the end should be adapted to allow for regular flushing.

As hot water service system main run is oversized a program of replacing with correct sizing would eliminate any hidden dead legs and maintain the correct temperature. All cold-water outlets switched to new boosted cold water service would also eliminate any hidden issues.