A traffic stop on Interstate 70 last week led to the arrest of a St. Louis County man on drug-related charges.A Foristell police officer stopped Sean Thomas Koehler, 20, Ballwin, shortly before 5:30 p.m. Tuesday, Oct. 18. The officer reported that Koehler was driving a vehicle with an expired license plate.When he approached the driver, the officer noticed a moderate odor of marijuana emanating from the vehicle, according to a probable cause statement filed in court.During a search, the patrolman found a nylon bag concealed inside a pizza delivery bag in the cargo area of the vehicle.Inside were three large plastic bags containing marijuana, a small bag containing marijuana hash/wax, a metal grinder containing marijuana residue and a glass smoking pipe containing residue, according to the statement.After he was read his rights, the suspect admitted to selling marijuana about three times a week and said he purchases the drugs in Columbia.Koehler is charged in a Warren County warrant with one felony count of distribution of a controlled substance and a misdemeanor charge of unlawful use of drug paraphernalia.His original bond was set at $25,000 but the judge agreed to accept 10 percent of that amount.Police said the total weight of the marijuana was about 1 pound and 10.4 ounces.Crime