I have been experimenting with an idea that Dennis gave me for a lid for my sumps. Neither sump is directly inside the shower. But sumps have pumps in them and must be accessible so that if they break down they can be easily replaced, and will also need to be cleaned on a regular basis so the easier they are to access the better. I have 8″ (200mm) inspection ports but I dont fancy having to do keyhole surgery through a 200mm aperture in order to uninstall and reinstall a pump inside the sump. So I was pondering how I might seal a home made lid when this idea came up.

We have some 30 liter white drums that once carried chlorine in commercial quantities. Dennis was given it to store dry things on board and was told it was procured from the local tip straight off the back of the truck disposing of them. So I contacted some local pool maintenance companies and they dont carry them but they put me onto the company that supplies them with chemicals and sure enough they had hundreds of them and often dispose of them when they have too many and they were happy to give me a few. In fact they gave me 10. I will use 2 for sump lids if they work out how I think they will and 3 or 4 on board to store things I want to ensure stays dry. This will also mean I will have spare lids if they are needed.

The idea is that these lids are screw on. They once held chlorine and as such I assume them to be fairly robust and fairly if not completely watertight when the lid is screwed on. By cutting the top off the drum and gluing that down in the sole the screw lid effectively sealing a wide opening into the sump making maintenance easy. There is even a flat ridge that forms a rim that will screw down with sealant under it to seal the join. The only complication is that the combination of male and female screw thread is about 45mm and I want the top of the lid when closed to be flush with the sole top so that it is imperceptible under the carpet when you walk over it.

To get the top to the correct height I need to glue the plastic lid into a ply surround and then glue (and glass) the surround 30mm below the bottom of the sole via ply side walls 30mm high, so that combined with the 15mm sole thickness the top will be flush. i will also glue a ply pad into the top on the outside to fill the centre and with 2 slots cut in it to aid in opening the lid. There is also a ring inside the lid that I will also fill with ply and attached through the plastic lid to the outer ply. I wont glue these 2 ply pads to the lid, I will just screw them to each other through the plastic lid, that way if I need to replace the lid I can easily switch it out by removing the screws and re screwing them to the new lid.

I cut the hole in the ply base to tightly take the bin top and a bigger hole in the sole to take the lid with clearance all around. I decored the balsa and back filled it so that tomorrow when I get on to making the access port I can sand the filled core to smooth and carry on without having to wait for it to set.

The idea to make this wide access hatch means that getting to the sump pumps and to keep the pumps clean will be much easier. I will have stocking feet over the in pipes to the sump which will filter the water (hair mostly) before it gets into the pumps and these will need to be cleaned on a regular basis, and whilst that would not be too difficult through the smaller port, getting a pump out then back in and secured is much harder through a small port.