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Assessing wastewater system damage

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There are two main methods we use to determine how much a pipe is damaged. Our aim is to get a picture of the damage type, location, and extent, which informs us how we can plan to fix it. When we have the information, we assess what we should do about it by comparing the current state to required quality standards.

In level surveys, our team of surveyors gather information about the levels (gradients) of pipes from the ground. They are able to do this at manhole entrances by:

  1. measuring the precise position and elevation of the manholes
  2. sticking probes into the manhole until the pipe is reached
  3. noting the depth of the probe
  4. comparing the difference in depth and the distance between two manhole points, which allows us to calculate the expected gradient.

From this information, we are building a digital 3-dimensional model of the city's sewerage network. Gradients can then be calculated and compared with historical information. Although this will give us information at the ends, it won't reveal any rises and falls within the length of pipe. Even so, they are a valuable pointer to problem areas that can be assessed with other techniques.

It's likely you will have noticed our surveyors using surveying equipment (theodolites and GPS) on tripods around the place. They will be clearly identifiable as members of SCIRT and wear high visibility clothing.

Using CCTV cameras mounted on wheeled buggies, we can assess damage up to 200 metres into a pipe opening. Our specialists control the buggies through the pipes from a specially equipped van. The entire journey through the pipes is recorded for later analysis. The operator also takes interim notes of the condition, and records data about the pipe's position and gradient.

We are also investigating innovative methods to get better data about rises and falls within lengths of pipes. We are undertaking these investigations cautiously with an emphasis on the value for money the techniques can provide.