As is required by law, the Regional District of Nanaimo monitors the quality of groundwater in the area beneath and surrounding its Cedar landfill.  The samples are collected from the 20 boreholes shown on the landfill map below (and on a larger version at: cedar-landfill-map.gif).  

Selected geochemical data from the sampling in 1999 are listed in the file cedar-landfill-water-chem.xls.  

Well # 15 was drilled through to the base of the older unlined part of the landfill, and it can be assumed that this water is strongly affected by leachate from the waste.

Using the data from the table, determine which wells (excluding #15) show evidence of leakage from the landfill.  Assume that leaking leachate should have characteristics similar to those of the sample from well # 15, but remember that this is only one sample, and that leachate from other parts of the landfill could be different.  You should also be aware that some of the more soluble constituents (such as chloride) will tend to remain in solution, whereas others, such as ammonia, may tend to be adsorbed by clay minerals and other materials, and not be dispersed a significant distance.  Take the data from uncontaminated Nanaimo Group water into consideration.  Results within the ranges shown are typical for water derived from these rocks.  (The landfill is underlain by Nanaimo Group sandstone.)  It might be useful to check out what background levels of some of these elements are by comparing these data with data from the nearby Yellow Point area that you looked at in Lab 7.

Please comment on your findings in a few sentences.  You should include some comments on: 

• the chemical nature of contamination of groundwater around the landfill, 

• whether you think that contamination is coming from the unlined or the lined parts of the landfill (or both), and 

• which direction the contaminated water might be moving.