Situation

Sewage pipe back-up occurred where raw sewage came out of floor drain in the staff room on the lower level (refer photos below). Affected area included staff room, large laundry areas, toilets, hallway all on vinyl and large maintenance workshop/storage (refer photos below) and flowed out into the car park and down the drain. Total area affected was 510 square metres. Sewer pipe was unblocked by local water authority.

Mitigation of cross contamination

In order to mitigate cross contamination, the car park area was completed first as this was an operating Commercial site where staff and customers required parking plus access to the foyer lift. Work commenced Tuesday at 5.30am to minimise disruption to the business.

Decontamination

The bulk of the decontamination took 23 hours based upon three Technicians attending. Maintenance area affected required decontamination of every item on the floor and the concrete floor pressure washed. Five pallets of floor tiles existed at the very back of the storage area which were left in place for the interim. Moved through the vinyl areas where again all items on the floor had to be decontaminated, the floor area pressure washed and items put back in place which were blocked up (use high density foam blocks to elevate contents off the floor) if required to aid drying. Five turbo dryers were left on site to aid drying for two days. The Maintenance area/Laundry areas where fully operational the next day.

Complications

Moisture Control Services (MCS) upon re-attendance, validated that the plaster walls in the staff room were affected where electrical and computer cabling metal skirts existed around this room. Power was isolated to this area which allowed the metal skirting to the dismantled and detached from the wall. Part of the plaster lower wall behind the metal skirting was off-scale (too much moisture to calculate a reading – refer photos below) and the affected plaster wall was removed and disposed (refer photos below). After this, all wires/cables, metal boxing and front metal sections were all decontaminated including surrounding floor area. MCS did advise our client that the end section of a built-in cupboard had swelled which should be replaced at a convenient time (refer photos below).

The pallets of tiles had wicked up with sewage and some of the packaging was wet. Client provided five pallets where MCS moved affected pallets to nearby area, removed/disposed of affected packaging (where applicable) and relocated clean tiles onto the new pallet. Original area where pallets were located was decontaminated (refer photos below), new pallets relocated back in place and the change-over area was then decontaminated which was the finalisation of the job (refer photos below).

MCS disposed of the five pallets affected by the sewage with the packaging.