4. Sewer systems. The acquisition, construction or reconstruction of or addition to a sewer system (either sanitary or surface drainage or both), whether or not including purification or disposal plants or buildings, land or rights in land, or original furnishings, equipment, machinery or apparatus, forty years; the replacement of such equipment, machinery or apparatus, thirty years; the replacement of such furnishings, ten years. The sealing of sewer lines by injection under pressure of polymers or other similar materials, substances or chemicals into open pipe joints or other leakage points in a sewer system (either sanitary or surface drainage or both), including inspection and testing procedures incidental thereto, fifteen years.