How many pounds of sand will be trapped per million gallons of water produced when pumping sand at 3 ppm by weight and installing a small trap?

• A. 10 pounds
• B. 50 pounds
• C. 25 pounds
• D. 100 pounds

Answer: (C)

The amount trapped per million gallons is found by converting the 3 ppm by weight into pounds of sand relative to the weight of a million gallons of water. A US gallon of water weighs about 8.34 pounds, so one million gallons weigh roughly 8.34 million pounds of water. At 3 ppm, the sand mass is 3 pounds per 1,000,000 pounds of water. Multiply the water weight by the ppm level: 8.34 million pounds × (3/1,000,000) ≈ 25.02 pounds. So about 25 pounds of sand would be trapped per million gallons, given the 3 ppm by weight and the small trap assumption.