When William Frederick Havemeyer became Mayor in 1873, Westervelt was appointed a Commissioner of Docks and at the same time elected President of the Board of Dock Commissioners (which position he also held at the time of his death), and as such made tremendous improvements in piers and docks. His chief engineer, whom he selected in July 1870, was General George B. McClellan, and his secretary General was Louis Fitzgerald. In 1875 George S. Greene Jr. became the new chief engineer. As Dock Commissioner, Westervelt followed in the footsteps of his father by continuing to improve the riverfront. In 1873 the draughtsmen and engineers in the office of the Engineer-in-Chief were engaged in the preparation of maps and drawings to show the grants of land under water, around, and adjoining the island of Manhattan which had been made by either the state or Municipal governments from 1696 till 1873. They were also been engaged in the preparation of plans for a proposed exterior bulkhead wall which was planned to be built all around the city. A new dock system was also proposed of which the main feature was a wide river street encircling the waterfront to afford ample accommodation for the movement of freight and its transportation by rail. The new river and sea wall was to be constructed of granite and a Beton concrete, composed of Portland cement and broken stone. From this wall projecting into the river were a series of piers constructed of wood, iron, and stone. The large concrete blocks used in the construction of the new river wall were manufactured at the yards of the Dock Commission in Gansevoort Street, Manhattan. Two to three blocks, of forty to fifty tons each, were made daily. Westervelt was closely involved in these improvements. Westervelt was politically an ardent but not very active Democrat. In 1840 he was elected to the Common Council, in which he served for two years as an Alderman from the thirteenth ward. Westervelt stepped back from active political involvement for a couple of years, but remained a shrewd observer of current affairs and recognized nuisances and the needs of the people of "his" town. He witnessed sharply increasing taxes between 1850 and 1852 and the establishment of a reform movement that began to decry excessive government spending. Grand jury revelations of widespread corruption on the common council heightened such concerns. Reformers mobilized and ran the Democratic incumbents out of office, electing in their place a combination of Whigs and reform Democrats committed to "economy" in government.