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Preventing soil erosion is a very important part of earthworks and engineering. A lack of erosion control can be disastrous and can result in major soil losses and pollution. The ability for soil to stay in place prevents erosion. We will be testing the effectiveness of adding polymer glue [Soiltac®] to soil to prevent erosion.
Our research methods consisted of taking compacted soil and applying polymer glue [Soiltac] with varying glue contents. The polymer [Soiltac] was mixed with water of varying ratios at (5:1, 7:1, 10:1, 15:1) and applied using a sprayer to saturate the soil. This created a crust that helps prevent both water and wind erosion. We found soil without polymer [Soiltac] was more susceptible to wind and water erosion, than soil with polymer [Soiltac]. The results from our research for the control showed a 49.6% loss due to wind erosion and a 40% loss of soil due to water erosion. During our wind tests, we found the average soil loss to be 5%, which is substantially better than 49.6%; however, the increase in concentration of polymer [Soiltac] did not provide a noticeable change in erosion prevention. The results from our water test showed a 35% reduction in soil loss with the addition of polymers [Soiltac]. Our 5:1 concentration lost 5% of its soil and our control lost 40%. We found polymer glue [Soiltac] to be a viable option for preventing wind and water erosion. We recommend a ratio of 7:1 for the most efficient results.
Understanding soil erosion is an important aspect to all contractors who deal with site or subsurface work, on a regular basis. Not controlling erosion can lead to costly problems. When talking about erosion, we are speaking about detachment of soil, sediment, or rock fragments caused by wind, ice, water or gravity. Almost all city and provincial municipalities have control measures in place to mitigate the amount of sediment and other pollutants carried by discharge or runoff into our wetlands, lakes and streams. The likelihood of erosion affecting public and private infrastructures in towns and cities is a problem that prompts city officials to take action and find a solution to this problem. One of the erosion control products is a polymer glue [Soiltac]. It is a liquid concentration that, when diluted with water and applied to the soil surface, bonds soil particles together. When [it] dries it forms a flexible crust that strengthens the surface of the soil. It creates a three-dimensional matrix in the soil resulting in enhanced stability and durability. Other benefits of using polymer glue [Soiltac] are that it is easy to apply, polymer [Soiltac] contains no harmful chemicals, and therefore it will not affect people, animals or aquatic life, and it has incredible strength. It is environmentally friendly, so it can be applied in all environmentally sensitiveareas, such as wetland, buffer zones and farming.
1.2 Purpose Statement
The purpose of this research is to find a suitable application of polymer glue [Soiltac] and adding it to soil. By doing this, we are trying to find a viable option to control wind and water erosion.
1.3 Research Questions and Hypothesis
Questions to Answer:
What is the effectiveness of polymer glue [Soiltac] against wind and water erosion?
What is the optimal water to polymer [Soiltac] ratio for prevention of soil erosion?
2 LITERATURE REVIEW
Various research has been conducted to analyze the wind and water effects on soil erosion Sepaskhah & Bazrafshan-Jahromi, 2006; Homauoni, & Yasrobi, 2011; Kavazanjian Jr, Iglesias, & Karatas, 2009; Moore & Siddiqim, 1981; Nader Abasi, 2016. All found polymers to be an affective product in preventing soil loss due to wind and water erosion.
Sepaskhah & Bazrafshan-Jahromi (2006) Found that Dune sands were stabilized using poly (methyl methacrylate) and polyvinyl acetate and examined using physical and mechanical tests. There results indicate that both polymers have good potential for increasing the strength of dune sands in the dry state. The results show that optimum added quantity of a polymer for maximum effect was 3% by weight and 28 curing time was the most effective. Nader Abasi (2016) had similar results using a Polyvinyl Acetate-based polymer to treat different soils. The polymer-added soil samples were investigated experimentally in a wind tunnel to verify the effect of polymer for wind erosion control of the soils and the results were compared with water treated soil samples. For silty and clayey soils treated with polymer, the amount of soil lost to wind erosion was reduced by a minimum of 90% in relation to the water treated samples. Kavazanjian Jr, E., Iglesias, E., & Karatas, I. (2009) results from his testing of polymers as a erosion control agent are complementary to the previous research he found that biopolymers can act as a stabilizing agent against wind-induced erosion. Both spray-on application and mixing of a biopolymer emulsion with the soil prior to compaction were shown to be effective.
Moore & Siddiqi (1981) did research with polymer as a means of preventing soil loss from wind and water erosion his results found polymeric materials in increasing the resistance of cohesion less sandy soils to wind and water erosion. Polymers such as polyvinyl acetate and acrylic polymers were found to be water sensitive in various degrees and consequently did not perform well. From a practical viewpoint, the application of polymers to soils by spraying has an obvious advantage over mechanically mixing polymers and soils. In the study they found that less polymer is required to provide no erosive surface if spraying is used. Homauoni, Z. J., & Yasrobi, S. S. (2011) also found polymers useful in preventing soil loss due to water erosion, there research was preventing water erosion generated from irrigation, they tested polyacrylamide (PAM) application with irrigation water. It was found that at steep slopes, higher PAM application rates are required to enhance the final infiltration rate, to reduce the runoff and soil erosion. The data also indicated that for steep slopes (up to 7·5%) higher PAM application rates as 6 kg ha−1 is required for runoff reduction especially at third irrigation. Thus concluding that the effect of PAM in reducing erosion was greater than in reducing runoff.
With the research from Sepaskhah & Bazrafshan-Jahromi, 2006; Homauoni, & Yasrobi, 2011; Kavazanjian Jr, Iglesias, & Karatas, 2009; Moore & Siddiqim, 1981; Nader Abasi, 2016; we can conclude that a polymer applied with a sprayer at the appropriate concentration for the given soil will be effective at reducing the amount of soil lost to wind and water erosion.
3 RESEARCH DESIGN
3.1 Research Methodology
We have conducted two types of environmental erosion tests on the soil, wind and water. Before we performed the tests, we had to do a sieve test on the soil in order to determine the size of the particles in order to classify the soil. The sieve test was performed by drying the soil, and then weighing it. After, we recorded the weight and put it through a series of screens that gradually decreases in size. The sieve rack was then put on a shaker, after it has shaken for a specified time, it was then removed. We then measured the weight of particles on each screen. We divided the weight of the sieve by the total weight of the soil, then multiply it by 100, which gives the percent of soil in that sieve. We used this data from the sieve test for erosion potential tests using the RUSLE test.
The RUSLE test uses the equation: A = R x K x LS x C
A = Annual soil loss, R = Rainfall factor, K = Soil Eros ability factor, LS = L and S are the slope length and steepness factors, respectively C = Vegetation and Management Factor and P = Support Practice Factor.
For the wind erosion test, we will place the soil in 24’’ x 24’’ x 3.5’’ box and compact it in two equal lifts with a plate tamper to 75% compaction. We applied our polymer [Soiltac]-water mixture to the soil. The mixture was applied in four different proportions; 15:1, 10:1, 7:1 and 5:1 (water: polymer [Soiltac]), respectively. The mixture was applied with a sprayer at a rate of 0.9l/m3. We took the weight of the soil in its saturated form once it was combined with the polymer [Soiltac]-water mixture. A leaf blower was used to blow air over the soil to act as simulated wind. We aimed for the average wind speed of Lethbridge (40km/hr.) This was recorded with a Kestrel Wind Meter. When the soil is finished being tested we took the weight of the soil and compared it to the previous weight ((W2/W1)*100) which gave us the percent of soil lost.
For the water erosion test. we tested the performance of the polymer [Soiltac] on two slopes: one at 2% slope and another at a steep, 50% slope. We used the same concentrations as the wind erosion tests 15:1, 10:1, 7:1 and 5:1 (water: polymer [Soiltac]). We sprayed water on the soil at a rate similar to a 1 in 50-year rainfall for Lethbridge. Due to spraying water on the soil, the moisture content of the soil will increase. Due to this change in moisture content, we had to calculate the moisture content of the soil before and after testing. With the calculated moisture content, we then calculated the proportions of the weight that was composed of water and soil. We subtracted the weight of the water from the soil so we could calculate the total corrected amount of soil lost.
WIND EROSION PROCEDURE
WATER EROSION PROCEDURE
Find moisture content of soil
Pre test setup
3.2 Data Collection
3.3 Data Analysis
The data from are tests was analyzed as percent of soil lost by weight. This is the easiest and most accurate way to determine the amount of soil lost to erosion. We did three tests for each polymer [Soiltac] concentration so we could get an average. This reduced the chance of having a value sque [skew] the test. With the data in the same units for both the wind and water erosion tests this allows us to compare the polymer [Soiltac] concentration in both tests. This shows us what the most effective polymer [Soiltac] ratio is to prevent both wind and water erosion.
4 RESULTS AND DISCUSSION
The use of polymer glue [Soiltac] prevented wind and water erosion of soil by 92% from no polymer [Soiltac] to a 5:1 ration. The increase in the concentration of polymer [Soiltac] had a correlation to the decrease in soil erosion. In the wind erosion tests, we found the 15:1 concentration to prevent soil erosion by 83% and the 5:1 concentration reduced erosion by 93% the 5:1 concentration is 10% more effective than the 15:1 concentration of polymer [Soiltac] at preventing soil lose due to wind erosion. In the water erosion test, the increase of polymer [Soiltac] also showed an increase in erosion prevention. The 15:1 was 45% effective and the 5:1 was 90% effective at preventing soil loss. The 5:1 is 50% more effective than the 15:1 at preventing soil loss due to water erosion.
A 5:1 water to polymer [Soiltac] ration applied a 0.9 liters/meter squared reduces soil erosion due to wind and water. The polymer [Soiltac] penetrates into the soil and forms a 15mm deep crust on the soil. This holds the soil in place and creates an erosion resistant layer. If this layer is compromised by wind, the soil will have lost the erosion protection it previously had. The study was limited by time and we did not get to test the durability of the polymer [Soiltac] with repeat tests on the same sample. As a result, we do not have data supporting how often polymer [Soiltac] would need to be re-applied to keep the erosion resistant layer to maintain the same erosion resistant properties. It would also be beneficial to test the polymers [Soiltac] erosion capabilities through many freeze-thaw cycles as happens in southern Alberta. The freeze thaw cycle in southern Alberta is very rapid and faces extreme winds from chinooks as well as water run off at the same time. These types of tests would provide an excellent idea of its durability and longevity in a natural setting.
5 SUMMARY, CONCLUSION, AND RECOMMENDATIONS
Soil erosion is defined as a process in which soil is removed from the surface via environmental stressors. These stressors include running water, rain and wind. Erosion of soil has caused many harmful effects in the world. According to Follow Green Living (2014), “every year about 75 billion tons of soil is eroded from terrestrial ecosystems all around the world”. Therefore, it is very important to reduce soil erosion to maintain the quality of land. Our goal was to find the most effective and environmental friendly way to control soil erosion against water and wind. When we started this research project, our main goal was to find a suitable glue [Soiltac] mixture content that will reduce the effect of wind and water erosion on soil. During the testing stages, in the 15:1 water test, we had an average loss of 23.49% of soil. In our wind test at a 15:1, we had a mean of 8.31% of soil loss. The 15:1 ratio was our lowest water-to-glue [Soiltac] ratio and by the tests we determined that it was the least effective against both water and wind erosion. The 5:1 was our highest glue [Soiltac] to water ratio and for its water test, we found to have an average loss of 4.28%, which was determined to be the lowest across all our other water tests. For the 5:1 wind test, we had an average loss of 3.49%, which we determined to be the lowest loss amongst all other glue [Soiltac] ratios. Incremental testing procedures gave us a more accurate way of collecting our data to determine the most effective ratio of water-to-polymer [Soiltac]. For our improvements, we could explore other research that better predicts the durability of the polymer [Soiltac] through repeat testing of the same application. Based on these types of further analyses, we could accurately determine the optimal amount of water-glue [Soiltac] ratios that should be used in order to prevent soil erosion.
Special thank you to Fabio Neto and Soilworks for their product and support. This made it possible for us to conduct our research in an economically friendly way.
7 Alsanad, A. (2011). Novel biopolymer treatment for wind induced soil erosion. (Unpublished doctoral dissertation). Arizona State University, Arizona.
8 Lyles, L., Armbrust, D.V., Dickerson, J.D. Y Woodruff, N.P. (n.d.). Spray-on adhesives for temporary wind erosion control. Retrieved November 2017 from https://infosys.ars.usda.gov/WindErosion/publications/Andrew_pdf/1077.pdf
9 Orts, W.J, Sojka, R.E., Glenna, G.M. & Gross, R.A. (n.d.). Preventing soil erosion with polymer additives. Retrieved November 2017 from https://infosys.ars.usda.gov/WindErosion/publications/Andrew_pdf/1077.pdf