Failed Inspection - Need Advice

Hi, We have a clear stream septic system – installed new in 2009. This is a system where there is a concrete tank for the waste coming directly from the house and then two other plastic tanks, the first of which has some air pumped into it and then the second plastic tank gets this effluent for more settling. Basically by the time the stuff gets past the last plastic tank the water is much safer for the environment. The leaching bed is 6 pipes, each about 20feet long (I think). We just put the house up for sale and have an interested buyer. One of the conditions for selling the house was to have the septic system inspected. We had that done yesterday and according to the inspector the system failed the test because of water in the leaching bed. The inspector dug 3 holes over the leaching bed. Here are the layers he dug through: • 6 inches of top soil; • About 1 ½ feet of sand;