Summarize the following paragraph in 50 words: With the continuous development of the scale of the city, the scale of the urban underground pipeline has also expanded. Urban drainage pipes, like the blood vessels of the city, are closely related to the healthy operation of the city. When the water pipe is silt accumulated, blocked, and ruptured, it may cause local waterlogging, and the leakage and damage of the sewage pipe may pollute the surrounding environment, so it is necessary to test the drainage pipe. Whether it is an old or new drainage pipe to be inspected, the main purpose of the old drainage pipe inspection is to check and evaluate the defects of the pipeline, see if it needs to be repaired, and also check the effect of the dredging project; The inspection of new drainage pipelines is mainly to check whether the pipeline is damaged during construction and backfilling, and to provide a basis for project acceptance.