CEE 721/821 Environmental Sampling and Analysis

1. (10 pts) A lagoon waste pit has the following historical data for the barium concentration based on a simple random sampling (n=4): 86, 90, 98, 104 mg/kg (the lower two thirds of lagoon). The regulatory threshold for barium is 100 mg/kg. The waste on this site was categorized to be hazardous, and therefore a more thorough sampling plan is needed. Determine the number of samples required so that the reported mean has a 90% confidence level.

2. (10 pts) Describe the special considerations and tools that can be used in taking water samples from: (a) flowing waters (rivers and streams), (b) static waters (lakes and ponds), and (c) estuaries.

3. (8 pts) Studies were conducted to test lead (Pb) concentrations in surface soils due to atmospheric deposition of emissions from a smelter. A total of 30 samples were collected, and the number of samples in each stratum was proportionally allocated based on the estimated percentage land area under the specified wind direction. The stratum weights and the resulting statistics of analytical results are shown below. Estimate the overall mean and standard deviation using the following equations.

4. A former small pesticide manufacturing facility was surveyed for pesticide residues in surrounding soils. Historical data have shown that the pesticide is very stable in soil, concentration is in the range of 40-200 ppb with a standard deviation of 5 ppb.

   1. (6 pts) If an error level of ±2 ppb is acceptable, how many samples are needed to be 95% confident that the requirement is met?

   2. (6 pts) If an area of 1 km² is to be surveyed, design the locations using the method of simple random sampling. Use Excel to generate random numbers and use the coordinate as shown below (i.e., (x=0, y=0) for the manufacturing facility; the range of x-axis for the whole site is from -500 to 500; same for the y-axis). Attach the random number from your Excel output and plot a x-y scatter plot showing the locations of all samples calculated from (a).

DETAILED ASSIGNMENT

20201001032727sampling_and_analysis_homework