A pre-sedimentation basin has been designed that reduces the river water suspended solids concentration from 500 to 200 mg/L. How many pounds of dry solids does this represent per million gallons of treated water? If the specific gravity of these solids is 2.60 (e.g. the solids have a density 2.6 times that of water, or about 2.6 g/mL) and the sludge removed has a solids concentration of 2% (on a volume basis), what volume of sludge must be removed every week at a design flow of 4 million gallons per day (MGD).