Extra Math Answers

  1. A system treated 1,566,350 gallons of water. Using water meter readings, they billed for 1,150,350 gallons and 22,000 was recycled and metered twice. What percent of the flow was Inflow & Infiltration?
  2. A storage tank holds 850,000 gallons. Currently the tank has 700,000 gallons. What percent of the total tank volume has been used?
  3. A system needs to dose 432 pounds of undiluted polymer per day. If the concentration of the diluted feed polymer is 1%, what should the chemical feed pump setting be in gpm?
  4. A wet well is 12’ x 10’ and has 9’ of water in it. If a 50 gpm sump pump is used, how long will it take to empty the wet well?
  5. The influent of a primary clarifier has a BOD concentration of 250 mg/L. If the clarifier effluent has a BOD concentration of 120 mg/L, what is the BOD removal efficiency in percent?
  6. If the gauge at the bottom of a tank reads 8.14 psi, how many feet of water would be in the tank? 8.14 x 2.31 = 18.8’
  7. The pumps in a lift station have failed and a portable pump must be brought to the site. If the lift station is 15’ x 15’ and the water level is 8’ from the top with an influent flow of 180 gpm, how much longer will it be until the station overflows?
  8. What is the Organic Loading Rate in ppd/1000 ft3 on an aeration tank that is 60’ x 120’ x 17’ and receives a flow of 1.73 MGD with a BOD of 160 mg/L?
  9. The BOD flowing into a treatment facility is 219 mg/L and the flow is 1.025 MGD. The MLVSS is 70% of the 4,200 mg/L MLSS and the aeration tank holds 2.09 MG. What is the F/M Ratio?
  10. The top of a water tower is 60 feet above ground level, and you want to fill the tower to a level of 55 feet. What pressure will a gauge at ground level read?

55 x 0.433 = 23.82 psi.