Each of the following is a key soil property to evaluate for site suitability prior to installing an on-site wastewater treatment system, except:
                            
                         
                        
                            
                        
                             
                            
                            
                            
                                Explanation
                            
                                
                                    Answer: C - The age of the soil is not a key property in determining the suitability of a site for an on-site wastewater treatment system. While the properties of soil may change as it ages, evaluating for texture, structure and density, among other properties, will capture age-related factors. Soil texture, structure and density all influence porosity and therefore its permeability - the driving factor in the effectiveness and safety of an on-site wastewater treatment system.