June 5, 1913: Engineering News article. Sewage Treatment Works for Fitchburg, Mass. “Sewage-treatment works, consisting of Imhoff tanks, sludge beds, sprinkling filters and secondary or final settling tanks are about to be built for Fitchburg, Mass., under a contract awarded in May, 1913. Special features of this plant are rectangular Imhoff tanks, built side by side with dividing walls, cement-plaster partitions forming troughs and gas vents, and the use of structural-steel frames to support the reinforced-concrete walls of the tanks and also the partitions just mentioned; the installation of the air lift for removing sludge from the Imhoff tanks, the approval by the Massachusetts State Board of Health of sprinkling filters, the first plant of the kind to be thus approved; the construction of sprinkling filters 10ft. in depth; the building of a 2-in. cement plastered curtain wall between the natural ground and the stone filling of the sprinkling filters.
The City of Fitchburg is located in the north central part of the State of Massachusetts on the North Branch of the Nashua River. In 1910 the city had a population of 37,826. A large number of manufacturing industries are located here on account of the excellent water power afforded by the numerous storage reservoirs along the river. The city is fairly well served by a system of sewers designed on the combined plan, which empty into the river at various points along its course. During the last two years, an intercepting sewer has been under construction, and at the present time is nearly completed, varying in size from 48 to 30 in. in diameter. The intercepting sewer will divert the sewage from the river and convey it to the trunk sewer through which it will flow to the sewage-treatment works. For a distance of 5500 ft. above the sewage-treatment works, the trunk sewer is in the form of an inverted siphon, constructed of 30-in. cast-iron pipe, at the upper end of which a chamber has been constructed with an overflow direct to the Nashua River, and a 36-in. stub for the future construction of an additional inverted siphon to be built when the normal quantity of sewage exceeds the capacity of the present siphon. Before the sewage enters the inverted siphon, it will pass through a grit chamber and coarse screen, where the gravel and sand will be removed and large objects, which might cause obstruction to the inverted siphon, will be retained. This grit chamber has been constructed in the sewer department yard where it will be readily accessible for inspection and cleaning.”
Reference: Marston, F.A. 1913. Sewage Treatment Works for Fitchburg, Mass. Engineering News, 69:23:1176, June 5.
Commentary: And thus the dumping of raw sewage into the heavily used rivers of the northeastern U.S. began to be curtailed. Intercepting sewers and rudimentary sewage works would begin to make a positive difference in river water quality. It would take many decades before the job was finished.