A Dive in Raw Sewerage

Protected with an environmental dry suit system

The Boss takes a Dip.

Recently the team at Descend Underwater Training Centre were contracted to survey a pumping structure for the Albury City Council. Now there is nothing very unusual about that except that the structure is 5 metres deep in primary sewerage.

Now eating and drinking are vital for human life support but of course what goes in must come out and it would only be the extremely curious who would want to know what actually happens after you press the button.. Well in fact what does come out slips down the pipes and is then transferred by pump to a large concrete lined holding dam at the treatment works. Here, large objects are screened out and a special poop eating bacteria introduced. Large pumps aerate the "product" to assist the aerobic bacteria and to prevent the "product" from going solid on the bottom of the dam.

Ultimately the waste is separated into a dry compacted cake like product that is non hazardous and can actually be re-manufactured into garden fertilizer and waste water which is further purified by ultra violet treatment and is supposedly good enough to drink but not recommended for that purpose. In our case it gets fed onto a tree plantation which is growing magnificently.

Now all that is pretty fascinating until you are faced with entering the primary pond. Our team is highly motivated but this one seemed to stop them in their tracks. Usually we play, paper -rock - scissors to see who gets to dive. Often I leave it to the newer divers who want to gain experience, and use my talents as dive supervisor but the boys were amazed on this day when I just told them straight up that it was my turn to dive. This really did not compute. Why would the boss "get into the poo" so to speak when he could have sent in one of them.

What they didn’t realise is that I would be totally protected with an environmental system while, on the surface, they would have to handle the dirty umbilicals, put up with the smell and then decontaminate me before I dressed out.

The preparation included updating our hepatitis shots and testing the AH3 free flow helmet and dry suit we were to use. The council also wanted to try and get some video footage. Now that was a real challenge as the visibility is totally zero and there is 150mm of thick sludge on the surface with the consistency of whipped cream.

We decide to try two techniques. One where we flush the area to be filmed with fresh water from a large bore hose. That proved totally unsatisfactorily but the second method where we filmed through a plastic bag of clear water held against the structure was much better.

I don’t think the engineers believed that we could give them the detail they needed by just a tactile inspection. In the end I think they were amazed. I could feel areas of corrosion where the surface metal had disappeared, test the security of welded joints, and finally found the answer to the vibration problem. Several of the anchors holding the structure had pulled out.

The real problem with a tactile search is not how much or how little you can feel, but the very real possibility of a needle stick injury and there is a disturbing amount of broken glass on the bottom, so it all needs to be done very gently.

After about 180 minutes on the bottom I had this terrible sensation that water was trickling down my check towards my mouth. I started to spit into the helmet. Was it just sweat, raw

sewerage is quite warm, or did I have a leak? (into the helmet that is!)

Actually after three hours in the dry suit it was time for the other sort of leak as well so I decided to get out. Now the team’s real job begins.

A power wash, followed by a biological wash and scrub down before the helmet is removed. Then it’s off for a shower and just in case, I use biological wash in the shower as well.

Now I’m hungry and settle into a sandwich and a cup of tea but the boys seem to have lost their appetite.