Method and apparatus for high pressure water treatment of the inside of a pipe section

A hydrodemolition apparatus for removing a liner material from the inside surface of a cylindrical structure, comprising a support for supporting the cylindrical structure in a horizontal orientation, a rotation mechanism cooperating with the support to enable the cylindrical structure to be rotated about a longitudinal axis of the structure and an elongated boom partially insertable into the structure, a first end of said boom comprising one or more nozzles oriented to deliver a pressurized jet of water to the liner to disintegrate the liner by hydrodemolition, a boom support for a portion of said boom that is distal from said first end of said boom, said boom support being located outside of said cylindrical structure, and a displacement mechanism for displacing said boom in a longitudinal direction, characterized in that:

• said apparatus further comprises at least one boom end support adjacent said first end of said boom, said at least one boom end support being adapted to roll circumferentially along the inside of said cylindrical structure;
• and
• wherein said one or more nozzles comprises:
• a first set of nozzles connected to a first source of pressurized water to impinge on the inside of the cylindrical structure at a first location;
• a second set of nozzles connected to a second source of pressurized water at a higher pressure than said first source;
• said second set of nozzles being spaced downstream from said first set of nozzles along a longitudinal direction of said boom to impinge on the inside of the cylindrical structure at a second location downstream from said first location.