The trapping of litter in waterways by means of flow retardation and screens
Date
1997
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: Solid litter constitutes a major part of pollution in urban stormwater runoff. This litter is not only unsightly, but also harmful to the natural water environment. Sightings of birds strangled in plastic bags are only one such an example.
Studies by Melbourne Water (City of Coburg, Australia) have indicated that plastic based products are the largest contributors of solid litter in urban stormawater runoff (approximately 62%), paper products (10%), miscellaneous (5%) and glass (2%). Although secondary "litter" (heavy metals, sediment, leaf matter and nutrients) and tertiary "litter" (faecal coliforms and pathogens) are also considered important pollutants, it is beyond the scope of this investigation.
Pollution of the recipient water-body via litter can be prevented by either trapping the litter in a stream (water-body) or by taking preventative measures such as street sweeping and public awareness campaigns. Most litter traps consist primarily of a screen and/or a settling basin, many of which have insufficient self cleansing capacity and require frequent maintenance to prevent excessive blockage and consequent upstream flooding during storm events. The risk of blockage is reduced by increasing the spacing between the bars of a screen, but results in reduced trapping efficiency. Limited success with existing stormwater litter traps create a need for the development of a new litter trap that would have the following desired properties:
• low risk of flooding due to blockages
• economical design
• simple mnintenance procedure
• low cleaning frequency
• low energy loss
• a non-blocking screen
• robust and vandal-proof
Description
Thesis (M. Ing.) -- University of Stellenbosch, 1997.
Keywords
Litter (Trash), Urban runoff, Dissertations -- Civil engineering, UCTD