Comparison of Erosion Control Products Using an ASTM D6459 Rainfall Simulator: Insights and Suggestions

Abstract

This study used a large-scale ASTM International D6459 rainfall simulator to evaluate performance of various types of erosion control products used in construction. Rolled erosion control products (RECPs), hydraulic erosion control products (HECPs), and soil amendments were tested and compared based on Cover factor (C factor), a parameter between 0 and 1 where 0 represents perfect erosion protection and 1 represents bare soil. All products behaved statistically similarly at the lowest rainfall intensity [5.1 cm/h (2 in./h)] with an average C factor of 0.03. At the next intensity of 10.2 cm/h (4 in./h), RECPs had significantly lower C factors than HECPs (0.11 and 0.41, respectively). Among the HECPs, Type 2 had worse C factors than other products, but all deteriorated at the highest 15.2 cm/h (6 in./h) intensity, reaching an average C factor of 0.48. Most (88%) products met their industry minimum specifications at the lowest rainfall intensity, but only 25% met them by the highest intensity. The soil amendments did not have published C factors, so their performance was compared to traditional products. Gypsum statistically matched the RECPs while Polyacrylamide (PAM) statistically matched the HECPs. Preliminary testing was performed on thee straw applications, but due to sampling differences only a soil loss ratio, or simple ratio of soil lost on the bare plot to soil lost on the treated plots, was calculated. A cost estimate obtained though local professionals revealed that the straw treatments appeared to be the most economical in terms of total dollars spent per reduction in sediment loss, and that the cost of premium hydraulic mulches did not appear to translate into improved performance. This study is useful because large-scale simulations more accurately reflect field erosion performance, but they are seldom performed due to time and cost considerations. In addition, varying intensities revealed performance differentiations, many product types were compared, and using an industry standard allows for confident comparison to other results. This study used a large-scale ASTM D6459 rainfall simulator to evaluate sediment loss performance of four types of erosion control products used on construction sites: rolled erosion control products (RECPs), hydraulic erosion control products (HECPs), straw mulch, and soil amendments. Under a 5.1 cm/h intensity, all products tested behaved statistically identically. As rainfall intensity increased to 10.2 and 15.2 cm/h, gypsum and RECPs performed better than polyacrylamide (PAM) and HECPs. Of the seven products that had available manufacturer specifications, all fell short of advertised performance. Preliminary results suggest that straw may be the most cost-effective erosion control measure of the methods tested. This study suggests that more adherence to nationally and internationally recognized testing standards is needed in the field of rainfall simulation. It also suggests that erosion performance data from large-scale simulators is more reliable than data obtained from small-scale simulators.