Abstract: In a drainage inspection chamber of the kind having a manhole access and a base with at least one channel in the base extending between an inlet opening and an outlet opening, the base is formed from plastics material and has an integral side wall structure, circular openings in the side wall structure constituting the inlet and outlet openings. Separately formed socket members for receiving inlet and outlet pipes are located at each of the openings, each of the socket member being provided with a resilient sealing member for sealing with the outer surface of a pipe fitted into the socket member, the sealing member also serving simultaneously to seal the socket member with the internal surface of the inspection chamber.

Abstract: A supporting arrangement for supporting a porous diffuser over a discharge opening of a gas supply pipe comprises a diffuser supporting body which defines a chamber with the porous diffuser and which connects with the discharge opening whereby gas is supplied to the chamber from the pipe. The diffuser supporting body has downwardly extending limbs which straddle the gas supply pipe and positively locate with the pipe in order to mount the supporting body on the pipe.