The other option is high ground water but if there is no evidence of this occurring previously it's not likely but again step 2 will tell you if that is the problem.Step 2 is to hire a competent local engineer or geologist that is a one man shop who specializes in this sort of project.

I was wrong, its main purpose was to remove ground water. 

However, in the late 60's there was a MAJOR train derailment there and it took 52 years for the final cleanup of the benzene in the groundwater.       

Many areas are updating their regulations because septic systems are at best rudimentary treatment systems and in areas of high concentration (>1 system per 5 acres) and high ground water, they are not adequate.

Outside of the chance that someone filled the duct system, either intentionally or by mistake, with water, the only explanation is a high ground water table that has allowed the water to leak in.

We look especially good when compared to California - AZ passed its Groundwater Act in 1980; CA just passed its first groundwater legislation last year.

However, it does sound like if there is any groundwater contamination then that isn't something I'd want to mess with.

Sometimes the ground water demineralizes the block wall and leaves it crumbly or it's a sugary texture.

For example a fire/dwelling policy including in-ground water hazard liability.Insurance is one huge headache for me.

Sometimes basements have seepage because of high ground water levels.