Consider the settling zone of a rectangular clarifier, as presented in class and as illustrated below. The length, width, and height of this settling zone are desingated by the letters L, W, and H, respectively. As presented in class, we have seen that the critical velocity () for this system is defined by the ratio: = Where represents the mean hydraulic detention time for this system. Recall that according to the model presented in class, particles that have a terminal settling velocity greater than or equal to will be collected with 100% efficiency. We have seen previously that is defined as follows: = Where = system volume. For the system illustrated above, = a. (5 pts.) Using this information, develop an equation to describe the critical settling velocity as a function of Q, L, W, and H. b. (5 pts.) Based on your solution to part a, how will the critical settling velocity (and particle removal efficiency) be affected if the height (depth) of the clarifier is doubled