How Strong is the Wind

Wind	Km/Hr	Wind Blown Litter
Calm	Up to 10	light film and paper
Light	10 -  20	crumpled dry paper, empty plastic bags
Moderate	20 - 40	light weight empty boxes, flat cardboard, paper products
Strong	40 - 60	corrugated cardboard boxes, sheets of Styrofoam, plastic containers
Gale	60 - 90	large boxes, sheets of ridge plastic, carpet, brush
Storm	90 - 117	construction materials (e.g. plywood sheets)
Hurricane	over 118	almost anything that is not secured
Tornado (F1 - F5)	105 - 322	dangerous winds

This table was derived from a litter study project for the Lethbridge Regional Landfill (Salbro Consulting).  Much of the information was adopted from a litter study that was done for the Pincher Creek Regional Landfill in the late 1970's.  The concept is that if was was dropped in these wind conditions, what litter would be carried by the wind away from the working face.   In the original Pincher Creek study, various materials were dropped from a 1.5 meter height in various wind speeds to observe what is carried in these winds. 

This reasoning was based on the idea that when waste is unloaded from customer vehicles at the working face, it is the point where the waste is most exposed to the wind.   

You may find in actual wind conditions that materials not identified in this table are carried by the wind and that some materials may not necessarily be carried by the wind, but may drift along the ground surface.  This table can be used as a general guide for different wind conditions, but shouldn't be thought of as a definitive description of what litter will blow in different winds.  

One thing that is clear though, "the stronger the wind,  the bigger the objects that will be blown by the wind".  

Also, keep in mind that two other factors that will have an influence on wind blown litter are turbulence and wind direction.  

Jim

Landfill Impact Assessment

I was just reading Landfill Impact Assessment report.  The report went to great lengths evaluating dust, noise, landfill gas, and odours.  It included a brief discussion on litter impact.  The study effort included a great deal of work using dispersion models that used climate and wind data, topography and so on to determine what impact, if any, there would be on nearby receptors.   The authors took great efforts to determine waste quantities for the next 35 years, modelled landfill gas emissions, conducted traffic flow assessments, and measured odour emissions from the existing landfill



The Blowing Litter Impact Assessment reported the following information:

Distance from landfill perimeter	Finding	Impact category
0 - 500m	50% of escaping litter remains in this area	Medium
500 – 1000 m	Remaining 50% retained in this area	Low
Beyond 1000 m	Very little escapes beyond this distance	None

This information was said to have been taken from a 'previous report' by RWDI (2002).  I did an internet search in an attempt to find the original source of this information, but was unsuccessful (so far).  I could not determine if this referenced report was related to the existing landfill at this location.  


A second table that was referenced to RWDI (2002) is said to be a study conducted in wind tunnels on "threshold speeds for various categories of wind-blown litter".   Again, I tried to find the original source of this information, so I don't know how this study was done.  Did it replicate waste in a pile, or did it replicate waste dropping from an unloading vehicle?  I would assume that we would see different results between the two scenarios. 

Wind speed range	Litter description	Impact category
0 – 22 km/h	No blowing litter	None
22 – 33 km/h	Newsprint, tissue, paper towel, some light bond paper	Light
33 – 47 km/h	All the above plus plastic bags, small boxes, small cardboard tubes, paper bags, plastic sheets.	Moderate
Above 47 km/h	All the above plus extensive heavy bond paper	heavy

The authors of the report suggested that the average annual wind speed 10 metres above the ground is 8.6 km/hr, and that it would be about 2.3 km/hr at the 2 metre level.  The authors then concluded that for the majority of wind velocities at the landfill, blowing litter would not occur.  This conclusion was based on the following table.

Table L2.34 - Frequency of Occurrence of Blowing Litter with Wind Speed
Speed range km/h	Annual frequency (%)
0 – 22	94.0
22 – 33	5.8
33 – 47	0.2
47+	<0.1

One can see if you connect all the dots using this information, you would come to a similar conclusion.    The authors further concluded that because most of the landfill operations will be below ground, this would further reduce wind-blown litter.   Recommendations suggested the litter mitigation should include, covering waste haul vehicles, daily cover of the working face, portable wind fences, improving vegetated lands buffering the landfill, educate the public about plastic bags, regular inspections and litter clean up. 


This evaluation is probably fairly typical of impact assessment studies. Litter issues usually don't get the same level of effort as other 'emissions' from landfills, even though litter is probably the most visible immission.  This may be because it is assumed that litter controls are very basic, such as cover, fencing, and cleaning up, that there's little need to do a complete evaluation.  Granted, because litter is visible and accessible, it is easier to respond to that a groundwater or gaseous emission impact.   I do think that landfill planners and engineers do need to give more attention to litter control and prevention.  They usually leave that up to the landfill manager and operators.   


I will admit, there may be more information available on specific litter controls in detailed operation plans.  At this time, I don't have that information. 


You can see the original report by going to the following link. 


https://muskoka.civicweb.net/Documents/DocumentDisplay.aspx?ID=5002