A water treatment plant treats an average flow of 3.40 MGD with a target chlorine dosage of 2.20 mg/L. How many pounds of 100% pure chlorine gas are required per day?

Formula Used: Chemical Feed (lbs/day) = Flow (MGD) × Dosage (mg/L) × 8.34 lbs/gal

Step-by-Step Mathematical Derivation:

1. Identify the given plant parameters: Flow = 3.40 MGD, Target Chlorine Dosage = 2.20 mg/L (ppm), Water Density Factor = 8.34 lbs/gal.
2. Apply the standard Davidson Pie formula: 3.40 MGD × 2.20 mg/L × 8.34 lbs/gal = 62.3832 lbs/day.
3. Round to the nearest tenth as required on standardized operator exams: 62.4 lbs/day.

⚠️ Common Exam Trap: Do not confuse MGD (Million Gallons per Day) with GPD or GPM. If flow is given in GPM, convert to MGD first by multiplying by 1,440 and dividing by 1,000,000.