Integrated rehabilitation

The outdoor nature of the Coffs Harbour Showground exhibition at Trenchless Live 2010 allowed Kembla Watertech to demonstrate live their newly-acquired access chamber M-Coating System in conjunction with the 3D Access Chamber Inspection System.

Kembla installed a 2 m deep manhole into the ground inside their exhibition area so that Trenchless Live visitors could witness an honest and realistic appraisal of how the system would perform in the field.

Comments made by visitors to all Kembla Watertech’s demonstrations focused on the occupational health and safety benefits of being able to survey, clean and coat the structures using specialised equipment that does not require the operator to enter the confined space.

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The M-Coating and 3D inspection systems can be used separately but, when integrated, offer a safe and efficient one-stop-shop for access chamber rehabilitation, the company said.

3D scanner

There is a high occupational health and safety risk factor associated with working environments like access chambers and wet wells. With Kembla’s 3D scanner, that risk is mitigated because there is no requirement for personnel to access chambers underground.

The set-up uses a sophisticated camera head on a pulley which scans the entire interior of the access chamber or wet well in a few seconds in one single vertical run.

The image data is transmitted digitally to the operator and can be used as a live picture survey for on-the-spot analysis, or saved for assessment in the office by either Kembla or the client personnel.

During the desktop analysis the operator can use the scanner software to stop at any position within the chamber, do a 360 degree pan, zoom in and out, perform an image capture and complete the analysis data.

Surface coating

Once the access chamber has been assessed using the 3D scanner, the decision to rehabilitate can be made. As an example, Kembla recently carried out a survey of a manhole in Rockhampton, Queensland.

The survey footage from the 3D scanner revealed the access chamber to be in a state of disrepair with corrosion-scale build-up. Kembla then used its specialised M-Coating System to clean and resurface the access chamber. As with the 3D scanner system, the M-Coating System’s specialised equipment has been designed such that confined space entry is not required for the operator. Cleaning and coating is carried out automatically from above the ground.

The M-Coating System

Stage one: cleaning and preparation

The TSSR Head (a specially designed cleaning nozzle) is lowered into the access chamber by way of a swinging boom and electric winch. The TSSR Head cleans the access chamber at a rate of 200 mm per minute using a high pressure water pump delivering 385 bar working pressure. The jetting nozzles are adjustable between 500 mm and 3,000 mm. In addition, Kembla has a separate nozzle specifically for grit blasting when the corrosion products are particularly hard.

The 3D scanner can be used after cleaning to confirm the surface is ready for coating.

Stage two: coating

The specialised mortar spray head automatically applies a coating thickness of 0.4 mm per pass on a 1,050 mm diameter shaft, at a rate of 1 m of height every 15 seconds. Thus, a specified coating thickness of 10 mm would require 25 passes and would take less than half an hour to apply. The result is a fully functional, cleaned and rehabilitated access chamber within a couple of hours.

Suited to the situation

A damp surface is to be expected inside an access chamber. While this may be a problem when using other coating materials, which require a completely dry surface, this is not the case for the M-Coating System. The M-Coating mortars are cement-based, meaning that a damp surface is beneficial for good adhesion.