1 2 3 4 5 Determine the particle settling velocity Determine

1. 2. 3. 4. 5. Determine the particle settling velocity Determine the width and depth of the grit channel at design average flow Determine the slot width Determine the theoretical length of the grit channel Determine the practical length of the grit channel assuming an extra 20 percent length for inlet and outlet turbulent conditions. Determine the velocity in the channel at peak flow and minimum flow and compare to the average design forward velocity of 1 ft/s. Hint: calculate the critical depth, DC, through the slot but remember that the water depth, He = 1.5 * 6. C. 7. One of methods of providing a constant forward velocity in the channel is to make it a parabolic shape. Select flow rates of 5 to 15 mgd in 2.5 mgd increments and determine Dc and the depth of water in the grit channel Calculate the area required for a forward velocity of 1 ft/s. For a parabolic channel the area of flow-2/3 * TW* He, where TW = top width of the flow and He-water depth in the channel. He-1.5 * Dc. Determine TW for each of the flow rates from 5 mgd to 15 mgd and draw the parabolic channel to scale. The parabolic shape can be approximated by a trapezoidal shape which is easier to construct as shown below

Solution

1)Settling velocity,

V= [rho×g×d^2(Gs-1)]÷(18×miu)

Miu=NS/m^2

d=mm

V=m/sec

rho= density of water

g= 9•81 m/sec^2