Changes

===Settling Velocity of Particulates===

===Settling Velocity of Particulates===

The process of sedimentation is enacted when solids "settle" to the bottom of a sedimentation practice, from suspension in moving or retained water (in this case a dry pond BMP). Due to dry ponds having grassy channels and slopes they are able to over time decrease the velocity of incoming stormwater flow that enters the practice. This combined with the agility of the practice to allow for temporary storage and ponding of water (48 - 72 hr) allows excess sediments (sand, silts, clay and small aggregates) and associated pollutants to settle and be retained within the BMP (Weiss et al. 2010)<ref>Gulliver, J.S., A.J. Erickson, and P.T. Weiss (editors). 2010. "Stormwater Treatment: Assessment and Maintenance. University of Minnesota, St. Anthony Falls Laboratory. Minneapolis, MN. https://stormwaterbook.safl.umn.edu/</ref>. These sediments should be removed periodically to maintain as designed performance of the feature. The following calculations are for measuring the settling velocities of various solids.

The process of sedimentation is enacted when solids "settle" to the bottom of a sedimentation practice, from suspension in moving or retained water (in this case a dry pond BMP). Due to dry ponds having grassy channels and slopes they are able to over time decrease the velocity of incoming stormwater flow that enters the practice. This combined with the agility of the practice to allow for temporary storage and ponding of water (24 - 48 hr) allows excess sediments (sand, silts, clay and small aggregates) and associated pollutants to settle and be retained within the BMP (Weiss et al. 2010)<ref>Gulliver, J.S., A.J. Erickson, and P.T. Weiss (editors). 2010. "Stormwater Treatment: Assessment and Maintenance. University of Minnesota, St. Anthony Falls Laboratory. Minneapolis, MN. https://stormwaterbook.safl.umn.edu/</ref>. These sediments should be removed periodically to maintain as designed performance of the feature. The following calculations are for measuring the settling velocities of various solids.

====Stoke's Law for settling solids====

====Stoke's Law for settling solids====

====Ferguson & Church (2004)<ref>Ferguson, R.I. and Church, M. 2004. A simple universal equation for grain settling velocity. Journal of sedimentary Research, 74(6), pp.933-937. for settling solids. http://geoweb.uwyo.edu/geol5330/FergusonChurch_GrainSettling_JSR04.pdf</ref>====

====Ferguson & Church (2004)<ref>Ferguson, R.I. and Church, M. 2004. A simple universal equation for grain settling velocity. Journal of sedimentary Research, 74(6), pp.933-937. for settling solids. http://geoweb.uwyo.edu/geol5330/FergusonChurch_GrainSettling_JSR04.pdf</ref>====

Ferguson & Church's calculation  

Ferguson & Church's calculation meanwhile allows for designers to include the relationship between settling velocity and particle diameter size. A relationship for settling velocity that incorporates larger particles, such as sands with Reynolds Number (RE) > 10, has been developed by Ferguson and Church (2004) as shown in equation 10.2. Equation 10.2 becomes Stokes' Law at small particle diameters and results in a constant drag coefficient for large particle diameters.