Given that the raw water flow rate entering a treatment plant is $3,000$ m$3/$day$.$ Design the fast mixing and slow mixing units accordingly indicating the key requirements for these units, excluding the chemical$($s$)$ and dosage$($s$)$ to be used for the fast$-$mixing unit. Make informed assumptions $($values within reasonable ranges$)$ and state the reasons for your assumptions of values for crucial parameters such as detention time, velocity gradient, depth and efficiency as relates to power requirements