title: Characterization of natural ventilation in wastewater collection systems.
abstract: The purpose of the study was to characterize natural ventilation in full-scale gravity collection system components while measuring other parameters related to ventilation. Experiments were completed at four different locations in the wastewater collection systems of Los Angeles County Sanitation Districts, Los Angeles, California, and the King County Wastewater Treatment District, Seattle, Washington. The subject components were concrete gravity pipes ranging in diameter from 0.8 to 2.4 m (33 to 96 in.). Air velocity was measured in each pipe using a carbon-monoxide pulse tracer method. Air velocity was measured entering or exiting the components at vents using a standpipe and hotwire anemometer arrangement. Ambient wind speed, temperature, and relative humidity; headspace temperature and relative humidity; and wastewater flow and temperature were measured. The field experiments resulted in a large database of measured ventilation and related parameters characterizing ventilation in full-scale gravity sewers. Measured ventilation rates ranged from 23 to 840 L/s. The experimental data was used to evaluate existing ventilation models. Three models that were based upon empirical extrapolation, computational fluid dynamics, and thermodynamics, respectively, were evaluated based on predictive accuracy compared to the measured data. Strengths and weaknesses in each model were found and these observations were used to propose a concept for an improved ventilation model.
authors.affiliation: SCH2M HILL, Englewood, Colorado 80112, USA. mward2@ch2m.com
authors.forename: Matthew
authors.initials: M
authors.lastname: Ward
authors.forename: Richard
authors.initials: R
authors.lastname: Corsi
authors.forename: Robert
authors.initials: R
authors.lastname: Morton
authors.forename: Tom
authors.initials: T
authors.lastname: Knapp
authors.forename: Dirk
authors.initials: D
authors.lastname: Apgar
authors.forename: Chris
authors.initials: C
authors.lastname: Quigley
authors.forename: Chris
authors.initials: C
authors.lastname: Easter
authors.forename: Jay
authors.initials: J
authors.lastname: Witherspoon
authors.forename: Amit
authors.initials: A
authors.lastname: Pramanik
authors.forename: Wayne
authors.initials: W
authors.lastname: Parker
mesh_terms: D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D015141:Los Angeles; D008962:Models, Theoretical; D013696:Temperature; D014691:Ventilation; D014861:Washington; D014865:Waste Disposal, Fluid; D018508:Water Purification
chemical_list: D000393:Air Pollutants