All connections with the sanitary sewer system before being covered shall be inspected and approved, in writing, by the Superintendent. As soon as all pipe work from the public sewer to inside the building has been completed, and before any backfilling is done, the Superintendent shall be notified and the Superintendent shall inspect and test the work as to workmanship and material; no sewer pipe laid underground shall be covered or trenches filled until after the sewer has been so inspected and approved. If the Superintendent refuses to approve the work, the plumber or owner must proceed immediately to correct the work.