Part 1:

1. Calculate the quantities [grams or mL] of each of the three disinfecting chemicals shown in Table 3 (attachment two) to prepare a 1% stock solution of disinfectant with a volume of 1.0 liters. For the commercial strength, find a particular commercial product and use their listed percent available chlorine in your calculations. Please include your source of information.

2. Using the example shown in Box 18-3 (attachment 3), calculate the quantities [kg or liters] disinfectant needed to treat 1,000 liters of water.

3. Assuming a water demand of 1,000 liters/day, estimate the weekly cost [$US] of treating the water for each of the three disinfectants. You can use local (USA) prices.

Part 2:

You are tasked with assessing possible health risks from two different wells in a region. Well 1 reaches a regional aquifer with a potentiometric surface 300 feet below ground surface. The aquifer material consists of mostly fractured 500 million year old metamorphic rocks. Well 2 is in a smaller valley with an unconfined aquifer with a water tale 100 feet below land surface. The water bearing units are unconsolidated to poorly consolidated river deposits of sand, silt, and clay, ranging from several thousand to several hundred thousand years old. Which well is more likely to have an arsenic risk and why?

4. You suspect that someone may have health problems due to long-term exposure to arsenic in drinking water.

List five physical symptoms that you should look for.

What is the first and most important step in treating their illness?

Is chelation alone a good treatment option? Why or why not?

You have a field test kit that tells you that water from a given well has an arsenic concentration of < 0.050 mg/L (50 µg/L, 50 ppb). Is this sufficient, or should you send a sample to a lab for testing? If you decide to send a sample to a lab, what is the minimum concentration that the lab should be able to detect?