Random sampling is the preferred method of sampling in this case of groundwater movement. Because the data was manipulated systematic sampling would have provided poor results. Also, bias sampling would have not provided the data needed because the data is random and it would not be systematically more likely to be selected as a sample than others. More than six samples is needed within this environment of gas-produced underground leakage. Eight samples would most likely have given the results through random sampling. This is because more samples would indicate the leaching that is occurring and where it is going rather than a small set of samples only showing a portion of the picture (Alchemy, 2022).
The plume of toxins moved west to east and stayed mostly in front of the main building complex. There is a hint of the toxin east but this is primarily through leaching. In-place treatment would be the best remedial strategy for this particular site. Because the fuel was introduced into the underground water the most likely remediation process through in-place treatment would be In Situ Bioremediation. This can be done by encouraging microorganisms to destroy or detoxify organic or inorganic toxins within the groundwater. Gasoline the fuel used underground in this case with a chemical structure of CH3NO would be more than perfect for in-place treatment. In Situ Bioremediation is the preferred method for CH3NO because of its low cost and uses microorganisms to detoxify substances involved in polluting the groundwater. However, even with in-place treatment comes the likelihood of monitoring as well. It is possible that some of the CH3NO could get into the bedrock and eventually leach into the groundwater again. This would indicate that monitoring of the groundwater is a necessity. After the clean-up through in-place treatment is finished a well-documented monitoring process should be put in place (EPA, n.d.).
Adequate sampling must be performed for the general situation that is described. Bias sampling should only be done when a general location of the polluted site is already known and no leaching is expected. Because TR-8 is 5000 PPM and TR-7 is 1000 PPM of BTEX indicates that rando sapling would be needed for indications of leaching within the ground water to outside of the main localized areas. This is proven with TR-1 showing 50 PPm of BTEX east of the main underground spill location. Also, to bear this fact TR-5 is 1 PPM of BTEX and TR-6 has 5 PPM of BTEX. The main indication that bias would not hold up is through the numbers where bias only found two 5000 PPM BTEX and random sampling indicated much more polluted areas than systematic random sampling or bias (Alter, 2020).
References:
EPA. (n.d.). INTRODUCTION TO IN SITU BIOREMEDIATION OF GROUNDWATER.
Introduction to In Situ Bioremediation of Groundwater (epa.gov)
Alchemy. (2022). What is Systematic Sampling?.
When to Use Systematic Sampling Instead of Random Sampling (alchemer.com)
Alter, B. (2020). Environmental Consulting Fundamentals Investigation, Remediation, and Brownfields Redevelopment Second Edition.
VitalSource Bookshelf: Environmental Consulting Fundamentals