Paper Explores Falling Water in Dropshafts; Earns Recognition

BY 
March 28, 2017

ASCE has honored the writing team of Wenming Zhang, Ph.D., A.M.ASCE; David Z. Zhu, M.ASCE; Nallamuthu Rajaratnam, P.E., F.ASCE; Stephen Edwini-Bonsu, Ph.D., P.E., M.ASCE; Jan Fiala; and Wayne Pelz with the 2017 Samuel Arnold Greeley Award for their paper “Use of Air Circulation Pipes in Deep Dropshafts for Reducing Air Induction into Sanitary Sewers,” published in the Journal of Environmental Engineering, April 2016.

In this selected work, the researchers investigated the phenomenon of falling water in dropshafts, which can induce large amounts of air into the airspace of sewers, the subsequent release of the pressurized air causing possible sewer odor concerns. The construction of a vertical airshaft that is connected to a dropshaft via pipes is expected to circulate the air and reduce air induction into sewers.

The study involved two deep dropshafts with drop heights of 24 and 11 m being retrofitted sequentially with air circulation pipes in a sanitary sewer system. Air pressure inside the sewer line and airflow rates inside the air circulation pipes were monitored throughout 2006-11. The results show that the retrofits reduced the manhole air pressure by about 10-47 percent.

The team’s study continues successfully from this point, and affirms the expertise of its members. Sewer air was indeed circulated via air pipes in the first dropshaft, while no circulation was observed most of the time in the second dropshaft because the air was directly pushed downstream by the upstream dropshaft.

The Samuel Arnold Greeley Award is presented for papers on the design, construction, operation, or financing of water supply pollution control, storm drainage, or refuse disposal projects.

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