New roofs!

Monday 11th March

It was the (now) usual trip down to Faridpur, and once we arrived we went straight to site.  The team at Practical Action have been working flat out to get everything ready in time for my visit, and they’ve done really well. 

Final adjustments being made to the new roofs at Practical Action HQ in Faridpur

We have a new reedbed installed, and the old filter beds have been emptied into new ones retrofitted onto the old flat-beds:

New reedbed with retro-fitted filter beds in the background

Baby reeds (cannas?)

New reedbed with tiny pencil thickness holes going into it that you can barely see at the bottom edge of the chamber…hopefully we won’t get them blocked!

New gate valves to control the flow out of the filters

The new height of the beds is partially to get the levels right for drainage into the reedbed, but also to aid delivery from a lorry bed rather than on foot.  They have a wide section to allow the truck to pull up next to the bed, and the barrels can then be tipped in directly, rather than needing to be lifted off onto the ground. We also have a new splash-plate resting on the top of the filter – a concrete 1.5ft x 2ft square pad – to minimise disruption to the sand layer when the sludge is poured in.

It looks so clean and tidy....

The office is taking shape and has a nice veranda to view the sludge drying from:

The new site office under construction

The treated sludge from last time is now resting in various states:

Sludge from the filter beds mixed with ash (grey pile) and sawdust (brown pile)

Sludge from the flat beds, not mixed with anything

We are now arranging to get some soil testing done on these to assess their nutrient value as compost (sulphur/ potassium/ nitrates/ phosphorous).

After looking at the new 2-part roofs, polycarbonate sheets bolted onto steel frames, it became clear that they are basically flat boxes with joins in. 

Roofs being delivered to site (I realise the irony of them being delivered by bike while our fancy NGO SUV sits idle in the foreground…!)

New box-section roof, with sliding end panel to adjust ventilation

This new flatness will not be good for directing rain off the sludge, or allowing condensate to drip away.  We considered building a small 1” lip on the eastern edge of the drying beds to aid runoff.  It would be preferable to have them tilted north-south, but this means runoff would have to travel the length of the bed, rather than the width, and there is a join across the middle – another learning point about making sure the orientation is right!  We started building this lip out of concrete, but in the end decided the quickest option would be to use corkboard (the stuff the firmer crashmats used to be made of in school gymnasiums) cut into strips and wedges to provide the required height and insulation.

Finally, we tied on the temperature sensors  to the roofs at 16:30, and made sure everything was in place and ready for the upcoming sludge delivery.