Realise, in high rise buildings suction pressure inside the drainage stack will continuously pull the traps (that means suck the water of the U traps leaving an empty and open U trap) if no vent pipe is provided, and creating COVID19 path into your home. The vent pipe is designed to prevent suction pressure (negative pressure) inside the drainage stack.
Filling each U trap once a week is not going to help if the stack in your building does not have a vent pipe (sometimes called balanced pipe) to relieve the pressure and prevent suction pulling the traps.
You don’t know what you don’t know, so go ask somebody who does :)
A residential building called Kwai Tung House in the Tung Tau Estate, Nga Tsin Wai is reported to have nine cases in six different units, where most of the patients come from flat number 15 (on different floors). CHP said maybe a structural problem (meaning drainage system) Dr Yuen will investigate.
UPDATE 11 December 2020
Environmental samples were taken from Block 6 apartments, COVID19 positive results were discovered on the piping, floor drains, and exhaust fans
Logically, it appears that COVID19 entered through the floor drain trap into the space (bathroom?) exposing the residents to the COVID19 virus.
The positive results discovered on the exhaust fans is a new development. Perhaps the exhaust fan handling contaminated air with suspended droplets itself becomes contaminated, and potentially discharges contaminated air. And when the extract fan is switched off, its a contaminated surface, risking touch/contact transmission. Safety precautions are needed for handling and cleaning exhaust fans.
Dr Chuang Shuk-kwan (11-12-2020) mentioned in passing that earlier investigations also found COVID19 in the fan system, although I don’t recall any announcement.
#exhaustfan #ventilation #HVAC
10 December 2020
Richland Gardens is a residential housing estate located in Kowloon Bay, Hong Kong comprising 22 high rise tower blocks, a small outdoor public transport interchange, and a medium sized shopping centre.
RTHK and SCMP have reported seven covid19 cases so far, located on different floors of the same tower, all in Block 6, and all residing in flat D. In addition, one case was reported in Block 4, and one case in Block 18.
CHP requires all residents in Richland Gardens Block 6, all floors, flat D, and Block 18, all floors , Flat E, must be tested, to me that indicates potentially more cases in Block 18 will emerge in the next few days.
After the horse has bolted, experts turned up to visit the Block 6 with microbiologist Dr Yuen, after the inspection Dr Yuen stated the drainage could be the source, because all the cases were in flat D, on different floors, but not every U trap could be seen (no access?)
RTHK managed to interview several Block 6 residents, who stated that the Block 6 drainage system was leaking!
Strange that BD, EPD or Dr Yuen didn’t mention leakage that in their post-inspection press conference. Dr Yuen did suggest pointed out that all residents in Block 6 should be quarantined, but the quarantine accommodation is already full, another no room at the inn story ✨✨✨
From bitter experience (e.g. SARS 2003) and other buildings, we know that sub-standard drainage systems can spread disease in the same high rise building, for Richland Gardens the early evidence tends to indicate that the cause is probably the poorly maintained drainage system (again). Has nobody heard that Prevention is better than the cure!
As shown in previously posted photos, it is easy to find located drainage systems that have not been properly maintained, but we have to wait for the next batch of people to be hospitalised before BD, EPD and HA pay a site visit.
Fingers crossed this cluster does not expand across the other 22 tower blocks in the estate.
In the good old days the topic was called Public Health, nowadays its called Plumbing and Drainage. It is essential for all buildings to have properly designed, installed and maintained sewerage systems to prevent infecting occupants, whether it is 2003 SARS, 2020 COVID19, or Influenza.
Recently, when COVID19 infection was discovered spreading within Hong Mei House, Tsing Yi on 10 and 11 February 2020, the RTHK report stated that the HK Government instantly reported it was not a “U trap” problem [RTHK link] a reference to the SARS outbreak in 2003 where the disease spread through the drainage system in block E Amoy Gardens infecting occupants, and requiring evacuation of the block.
youtube is unreliable at the moment, here is the link https://www.youtube.com/watch?v=GTNvTuV_CM4
I predicted the cause would be the sewer vent pipe, vent pipes are part of the high rise drainage system designed to prevent loss of the water seal in U traps. Subsequently, my suspicion was confirmed, the SMCP newspaper confirmed that the vent piping inside the bathroom was damaged (see SCMP photo below). Therefore, droplets could contaminate the bathroom area.
Still problems in 2020
The photo below taken 15 March 2020 shows damaged drainage system vent piping.
That drainage system is damaged, it is no longer an enclosed system, allowing odour, bacteria, virus to escape into the air.
We have always known that sewerage and drainage systems are important, providing a conduit for bacteria and viruses, yet the severe lessons from SARS in 2003 and now from COVID19, demonstrate lessons still have not been learned!
A resident on the top floor (34th floor) of Heng Tai House, Fu Heng Estate, Tai Po has been diagnosed with the novel coronavirus COVID19 today (14-3-2020) RTHK reports [link] and he lives two floors above a couple already diagnosed on 11 March 2020 (same flat number ending with 13).
This is eerily similar to the incident in Tsing Yi in Feb. 2020, where I predicted drainage vent pipes issues, the pipe was subsequently discovered to be damaged, and additionally, repairs were carried out in nine (9) flats while those residents were evacuated.
This time, residents in Heng Tai House living in flat numbers ending with 13 and 14 , and living six floors below the “latest case” on 34th floor (top floor) will be evacuated RTHK reports [link].
Why this evacuation is limited to only six floors seems strange, citing droplets from the roof vent (which one?) reentering the building as the reason. While it is not impossible, the airflow pressure and patterns created around buildings are very complex, it seems highly unlikely, that only flats 13 and 14 would be impacted in this style of public housing.
It is worthwhile remembering that in the workplace, employers are responsible, by law, for the Health and Safety of their employees! Therefore workers in high traffic areas, for example, healthcare, building management, sewerage plants, transportation, etc. are responsible for their employees Health and Safety (H&S).
14 March 2020 – Another similar incident is reported at Heng Tai House, Fu Heng Estate, Tai Po [link]
RTHK reports [link] some apartments in Hong Mei House, a residential tower block located in Tsing Yi, Hong Kong have been evacuated overnight after another person was diagnosed with the novel coronavirus (covid19) living in the same building, 10 stories directly below a person already diagnosed with the infection.
And fearing a repeat of the SARS in Amoy Gardens Block E, the HKSAR Government swiftly reported that the drainage U traps are in “good condition”.
Notwithstanding, the condition of the U trap, not every building (see photo below) has U trap fitted.
In addition, we must also consider faulty vent pipes (refer to our photo below). Vent pipes are connected in parallel to the main sewer system, well they should be, therefore any broken, damaged or disconnected piping provides an equally risky conduit for droplets and pathogens to spread into homes.
As shown in this video clip below, if the bathroom is negatively pressurised, pathogens can be dragged into the bathroom contaminating surfaces, risky infection of the occupants.