I live on the Scottish Coast in a small settlement that has no mains drainage. We void our house sewage directly to the sea via a 6" cast iron outfall pipe with an outlet to the mid-tide line - don't ask it's Scottish Water's problem to comply with EU Directives by next year!
The outfall is supported at intervals on concrete piers of about
1000x800x600 DWH. The shore is pebble and rock. We are exposed to Southerly storms. Two of these piers are crumbling away in a pretty bad state and need to be recast. I guess that I will just trim down the existing piers, build some rectangular formwork and pour concrete... more or less.My question: any advice about type of cement? should it be rapid-set?, what mix? and are there any special additives that might help to keep strength and minimise corrosion in the pipe when the piers are immersed in seawater 50% of the time.
It may be that someone has experience of casting concrete as a seabed mooring with chain if no direct experience of sewer pipes. Cheers
-- Iain Donaldson