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→Geotextiles/filter fabric
e.g. In the image on the left 23 % of the grate is impassable. The clogging factor is 1.00 - 0.23 = 0.77.
e.g. In the image on the left 23 % of the grate is impassable. The clogging factor is 1.00 - 0.23 = 0.77.
==Geotextiles/filter fabric==
==Geotextile or filter fabric==
*Clogging of [[filter fabric]] has been observed in many field studies, e.g. ''"outflow ceases while water is still ponded above the drainage layer is most likely due to fines clogging the fabric and the need for more hydraulic head for the water to pass through the fabric"''<ref>Willard, L.L., T. Wynn-Thompson, L. H. Krometis, T. P. \ Badgley, and B. D. Neher. 2017. “Does It Pay to Be Mature? Evaluation of Bioretention Cell Performance Seven Years Postconstruction.” Journal of Environmental Engineering 143 (9).</ref>
*Clogging of [[filter fabric]] has been observed in many field studies, e.g. ''"outflow ceases while water is still ponded above the drainage layer is most likely due to fines clogging the fabric and the need for more hydraulic head for the water to pass through the fabric"''<ref>Willard, L.L., T. Wynn-Thompson, L. H. Krometis, T. P. \ Badgley, and B. D. Neher. 2017. “Does It Pay to Be Mature? Evaluation of Bioretention Cell Performance Seven Years Postconstruction.” Journal of Environmental Engineering 143 (9).</ref>
==Pipes==
==Pipes==
Some clogging of perforated [[pipes]] is likely to occur between maintenance visits. As mentioned above a clogging factor of 0.5 is often applied. See [[Flow through perforated pipe]].
Some clogging of perforated [[pipes]] is likely to occur between maintenance visits. As mentioned above a clogging factor of 0.5 is often applied. See [[Flow through perforated pipe]].
Pipes with smooth internal walls make for easier operation and maintenance.
Various opinions are offered about how to mitigate the accumulation of sediment. The appropriate solution may depend on whether the water is flowing into the pipe (see [[underdrains]]), or out of the pipe as in [[exfiltration trenches]].
Various opinions are offered about how to mitigate the accumulation of sediment. The appropriate solution may depend on whether the water is flowing into the pipe (see [[underdrains]]), or out of the pipe as in [[exfiltration trenches]].