The assessment methods which are used to confirm the correlation between the specified (tender) and actual services should include:

• Optical inspection of the manhole and access shafts

• Optical inspection of the sewer line, via mirroring or video inspection

• Where appropriate, sewer measuring boat, culvert pressure unit, sonar measurement

The contract specifications should outline whether these tests are to be carried out at random or over the entire length of the cleaned section. It should also be specified which type of inspection and assessment method are to be used.