Presentation on theme: "The Removal of Urban Solid Waste from Stormwater Drains Summarized from readings supplied by Dr. Neil Armitage University of Cape Town, South Africa 2006."— Presentation transcript:
The Removal of Urban Solid Waste from Stormwater Drains Summarized from readings supplied by Dr. Neil Armitage University of Cape Town, South Africa 2006
Combined sewage litter and other floatables, Fresh Creek, Brooklyn, NY
What is Litter? Other names (trash, debris, flotsam, jetsam, floatables, gross pollutants, rubbish, solid waste) –Includes (but not limited to): bottles, cans, plastic and paper wrappings, newspapers, shopping bags, cigarette butts and packets, hypodermic needs, used car parts, construction rubble, and even mattresses and shopping carts!
Where does it go? Eventually, maybe, to the ocean. Entangled in vegetation. Strewn on beaches. Buried in sediment
Impacts of Litter in Waterways Aesthetically unattractive Potential health hazard to humans associated with putrefying contents of bottles and cans Pathogenic organisms attached to needles Aquatic fauna entangle in and/or suffocate from ingested litter Release and uptake of toxic chemicals and microorganisms Cost of waterway cleanup can be high!
Contributing Factors to Composition and Quantity of Catchment Litter Type of development Development density Community income level Type of industry Rainfall patterns (long dry spells provide more opportunity for surface cleaning before rain washes the litter into the drainage system) Type of vegetation (are leaves the cause of concern?) Efficiency and effectiveness of refuse removal services. Level of environmental concern in community. Extent of legislation/regulation preventing waste generation and/or controlling disposal options Level of fines in the legislation for improper disposal
Composition of Collected Gross Pollutants by Dry Mass from Different Catchments
Land-use TypeLitter Load excl. vegetation (kg/ha.year) Vegetation load (typical) (kg/ha.year) Residential: Low Density Residential130 Medium Density Residential1530 High Density Residential15030 Informal Settlements (no formal refuse removal services or stormwater reticulation, but within 50m of an open drainage channel) 600010 Manufacture/Industrial755 Retail250030 Offices5030 Halls, Stadiums & Entertainment Facilities 30030 Taxi Ranks etc.600030 Schools10030 Hospitals5030
Two Different Approaches Prevention Remove litter once in the drainage system Advantages? Disadvantages?
Reducing the Litter Load Two categories of reduction methods: –Planning controls Restricting litter-generating activities to areas where their impact can be most effectively controlled and reduced –Source controls Reducing litter loads entering the drainage system through public education and enforcement programs At some point, also must include source controls
Planning Controls Aimed at adopting land-use policies which: –Preserve existing valuable elements of the stormwater system –Minimize the risk of litter reaching the drainage system –Require pollution control measures
Fluorescene tracer discharge in Boston, MA, to detect sanitary sewage connection to storm drainage system
Public education/training to encourage public awareness of urban water conditions
Signage for public education to enhance awareness and respect for urban waters.
Source Controls Aimed at reducing the litter loads entering the drainage system by dealing with pollution at the source –Upgrade cleaning operations (more frequent litter collection points, improved street sweeping, etc.) –Control construction activity –Determine which businesses/activities in area generate litter –Litter education campaigns –Improve enforcement of anti-litter regulations –Tax products (including packaging)
Structural Controls Ideal trap characteristics: –Reliable –Economic to construct and operate –No moving parts –No external power source –Minimal water head requirement –Does not increase flood levels near structure. –High removal efficiency