Plastic riser ring support - Standards around ground support

[Jono1uk]

I have a new build with a private sewer that passes under raised decking which was installed by the builder. There are access chambers comprising of plastic riser rings, the frames for the covers are not held down in any way, there is infill support to one side of the riser, while on the garden side 12" to 18" of the plastic rings are visible and have no support at all. Adding infill on this side will result in earth against the vertical deck boards. I am concerned that in time as a result of settlement the riser my get pushed over or the rings pushed off, I'm pushing the house builder (national company) to put in some supporting block work but they are trying to fob me off. Are there any standards that require plastic risers to be in the ground? I am told the supplier is Polypipe but can not find any manufacturers guidelines for this.

[seanandruby]

What type of cover are they? The round metal one has lugs on the side to put holding down bolts, the plastic square ones have 3 screws on the inside lid which should be tightened. The universal I C can only be 1200 deep, so 3 risers only. You can backfill around them as the weight of the backfill against the fins hold the risers in place. They can only take 1.5 ton on the cover unless the cover is supported by a plinth. Having compacted the fill ( 40ml max size or less, as dug, shingle, or dpt1.) Around the risers by tamping down, you can place 150 ml deep by 700 wide concrete plinth. The concrete shouldn't touch the sides of the risers, so you need to isolate it with something. Once there is a plinth the cover can take 4.5 ton plastic, or 12 ton metal light duty. Not sure if yours is taking any weight or not. Go to Osma drains inspection chambers on line for more information, also sewers for adoption and building regs' part h. Any photo's by the way?

[Jono1uk]

Many thanks for your reply, I will take a look at the OSMA site and see if there is any info. I can not take a photo just now because there is scaffold on the decking covering the trap door. There are posts that take the load of the decking and so I do not think weight is a problem. The soil/crushed material under the decking is however just infill, and so as rain passes through the decking over time it will settle.

[Donk]

if its in the garden then soil is normally banked around it with the lid just below grass level so you can mow over the top of it.you wont be knocking it off easily as its packed into the ground with the base of the chamber concreted in place. If its under a deck how are you going to access it if you need to rod ?

[seanandruby]

Wouldn"t normally concrete the base in place but people do and surround on concrete which goes against recommendations for this type of chamber.