The type of septic system in question, which operates by gravity, is used in about 4,600 homes in Carver County. County officials estimate that at least 3,500 of the systems are not in compliance with a rule that their drain fields must be at least 36 inches above the historic level of the groundwater below.
When that new rule went into effect in 1996, the county grandfathered in existing systems but required that they eventually be repaired -- usually by placing the drain-field distribution system into a mound at a cost of $10,000 to $15,000. The county now requires that the upgrades occur when a property is sold or requires a building permit.
