Recycled plastic survey pegs and stakes
30
business points
I am looking at the advanages and disadvantages of recycled plastic survey pegs and stakes that are put into the ground. Currently most survey companies as well as ours use wooden pegs and stakes which do break down but are increasingly becoming an OHS issue. What are the advantages or disavantages in using plastic pegs and stakes rather than wood in an Environmental sense.
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424
business points
Dennis you raise an interesting and important question. The issue boils down to the life cycle of each product. Traditionally this was referred to as ‘Cradle to Grave’ or the birth of the product in its life cycle, from extracting the resource (in the case of the wooden stake it would start with the harvesting of the tree) to the death of the product when it is returned to the earth as landfill.
Regarding your question, a good way to understand this is through a Life Cycle Assessment (LCA) of both products. As far as I can find, there is no such comparative assessment done for survey pegs but some literature exists around the LCA for wooden versus plastic pallets. The following link http://igps.net/advantage/lca.php will take you to an LCA of plastic versus wooden pallets.
Here is a useful article which helps to unpack some of the assumptions which were built into the LCA and how these processes can be used to argue either side of the debate. It also presents the pros and cons of using plastic versus wood. http://lovettpalletrecycling.wordpress.com/2010/04/14/life-cycle-analysis-underscores-environmental-challenges-of-plastic-pallets/.
What this article concludes is that functional life of the product is a major determinant in how environmentally sustainable it is. The upside of your plastic pegs option is that they are not virgin material but recycled. Added to this, it sounds as though the wooden stakes have both a shorter lifespan (easily damaged) and present OH&S issues if damaged. As I’m sure you have discovered in your search for a plastic alternative, there are multiple different designs which apply to different applications. Finding the right design that suits your needs will most likely determine the products longevity and subsequently its environmental sustainability.
27
business points
Dennis you certainly have raised a question! As the surveyor stakes are predominantly used as a short term consumable where they are used for long term applications the environmental impact in relation to CO² emissions changes. Paul's analogy with the pooling pallet comparison gives an indication of plastic verse timber and it is clear that a number of cycles of the plastic product have to be much greater for the benefits of CO² emissions be realised where as with the timber stakes compared to light weight equal strength recycled PET only needs to be recycled once to equal timber and have twice the life expectancy.
On first view wooden pegs would be the best option as they store C referenced to CO² emissions , which is the most common measure in the life cycle performance in relation to the environment for a product that is normally considered as a consumable and only used once . OHS issues of the timber based low cost product are a consideration as to the cost , transport and utilisation of the product in the field are all considerations.
First the recycled plastic stakes must be able to perform equal or better in the application then it is a simple task to gauge the environmental impact in terms of CO² emissions for the stake from raw material supply, to being utilised in the field, as most cases the surveyor does not recover or reuse the stakes , either the stakes are disposed timber or possibly recycled or collected for use by forward contractors this has been observed with the plastic stakes as they have recognised value.
Reviewing the table below it would be a reasonable to consider a post or stake could be reused once making the Fibopost 290XT comparable in the sense of CO² emissions , other plastic products are only comparable when they can be recycled / reused a number of times.
One further consideration is that the life of a timber stake in the ground the Fibopost will be 20x's the life of the timber , Polypropylene and Polyethylene based recycled products will not have the same long life as the Fibopost (“70% polyethylene terephthalate: 30% glass”) as they will and degrade.
The assumption can be made that the multiple of the increase in years of life expectancy can be determined for example if a timber stake has a life in the field of 5 years the Fibopost will have to have a life of 5 x 1.9 = 9.5 years to match the same life kg CO² emission of a timber equivalent post , similarly 14 years for recycled polyethylene and 32years for virgin Polypropylene equal post .
This is represented as a simplified summary as a guide. Reducing the land fill is not taken into consideration , the utilisation of the timber into a more carbon efficient product would also be a consideration, that is not accounted for .
In addition the accountabilityy of the current accounting systems for CO² emissions is still under debate especially in regard to the recycled content , when a product is recycled should the total CO²emissions up to the end of the life of the recycled component be taken into account this could significantly alter the tabled information below for the Fibopost 290XT the emitted CO² would change from -646 kg eCO²/1000 posts to -1773 kg eCO²/1000 posts ( this is a consideration as the recovered PET for the Fibopost has littlerefinementss to be manufactured into a end Fibopost product) hence the timber posts would not be considered the best option in respect of CO² emissions.
Commercially as carbon becomes accounted for in some form the cost of production this will increase and the cost of the timber stake to manufacture will increase disproportionally to the Fibopost product just on carbon cost this is not shown in the table as the stored carbon value of the timber is accounted for hence if the timber post goes to land fill and the stored CO² is released the timber stake is not the best environmental option.
Summary:
Based on the current accounting systems for CO² emissions each alternative to timber must be reused or recycled, this becomes a consideration in the field , but if the other factors are considered that are not considered in the single environmental impact table like ; depletion of resources , uses of carbon storage like timber / wood where they maintain long term storage, product recognition for recycling reusing , OHS issues for example 1000 timber posts 0.75m³ or Fibopost 290XT 0.55m³ a 30% reduction in volume and a 25% reduction in weight, any colours and high visibility the alternative recycled products will outperform the traditional timber and wood stakes with efficient design utilisation of the recycled resources.
Table:
Contact for copy of table
Product
kg/ 1000 posts
kg CO² emission / kg manufactured product
kg eCO²/ 1000 posts
kg eCO²/1000 posts shipped 300km (light commercial)
kg CO² emission / 1000 posts recycled
total kg eCO²/1000 posts
breakage/ wastage
total utilisation field kg eCO²/1000 posts
number of times required to be recycled / reused to equal timber stake kg eCO²
Increase in life expectancy x years
timber hardwood 1200 x 25 x 25 mm surveyor stake painted white on the top
480
-3
-1440
9.5
0.48
-1433
15.00%
-1218
-
-
Fibopost 290XT – 1200mm white / off white – 70% recycle content
360
0.06
19.8
7.13
-673.2
-646
0.00%
-646
1
1.9
Polyethylene recycled post 1200 x 25 x 25 mm
700
0.45
315
13.86
-770
-441
0.00%
-441
3
2.8
Virgin polypropylene 1200 x 25 x 25 mm
650
5.5
3575
12.87
-650
2943
0.00%
2943
7
6.4
Reading and references:
Transport light commercial 0.066 kg eCO² / tonne.kilometer
GREENHOUSE GAS EMISSIONS FROM AUSTRALIAN TRANSPORT: Base Case Projections to 2020 - Report for the Australian Greenhouse Office (AGO), Department of the Environment and Heritage – August 2005
kg CO² emission / kg disposed- recycled
Measuring the Environmental Impacts of Discards Management: Models, Methods, & Results by . Jeffrey of MorrisSound Resource Management : EPA Webinar live at CRRA -August 5, 2008
LIFE CYCLE INVENTORY OF 100% POSTCONSUMER HDPE AND PET RECYCLED RESIN FROM POSTCONSUMER CONTAINERS AND PACKAGING by FRANKLIN ASSOCIATES, A DIVISION OF ERG PRAIRIE VILLAGE, KANSAS APRIL 7, 2010
National Carbon Offset Standard (To come into effect on 1 July 2010 coinciding with the cessation of the Government’s Greenhouse Friendly program) Department of Climate Change
Note : values in this table have been extrapolated from data for comparison and while considered accurate for the demonstration of CO² emissions and is based on knowledge and understanding at the time of writing users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate agency.
