Below ground block work

chunky · Post: # 32090Post **chunky** Sat Oct 11, 2008 4:23 pm

I want to build a light weight chamber on top of a rain harvest tank approx 1300X500 can any one suggest a light weight block.

flowjoe · Post: # 32097Post **flowjoe** Sat Oct 11, 2008 7:43 pm

Thats a hell of an access chamber Chunky.

Can you not reduce the access and use lighweight plastic or concrete rings at one or either end ?

Photos would help

Sat Oct 11, 2008 9:47 pm

concrete blocks or class B s underground FTW!
LLL

chunky · Post: # 32121Post **chunky** Sun Oct 12, 2008 2:29 pm

Hi Flowjoe there is a 500mm dia access tube on top of the Klargester rain water tank,i need to build up around this to cover the opening and also provide an enclosed space next to the access tube for a valve and filter,i have two frames and covers to put end to end hence the 1300mm length i would require 36 blocks to build and bring up to ground level which although the tank has been back filled i`concerned about the weight. cheers Chunky.

Post: # 32122Post **seanandruby** Sun Oct 12, 2008 7:38 pm

what do klargester recommend.? cant you cast a reinforced concrete slab across it to spread the load?

flowjoe · Post: # 32123Post **flowjoe** Sun Oct 12, 2008 9:14 pm

There should be instructions with the tank on forming a reinforced base around the neck/tank but i am usually a bit wary of settlement on new installations.

You can buy an extension for the neck direct from the manufacturers but dependant on where the tank is sited i would use plastic chamber rings myself on a lightweight base, put two chambers side by side if needed. If they are to take vehicle weight then you will have to go belt and braces with it and install a solid reinforced base as sean said.

Post: # 32126Post **seanandruby** Mon Oct 13, 2008 4:45 am

hope its a dry area otherwise it could turn into the yellow submarine surfacing.

you could put sand, or polystyrene under the slab to take the pressure of it when you cast the slab.