This subtitle does not apply to: the random placement of broken stones or rubble as a foundation, sustaining wall, or similar structure to control erosion; or to the otherwise lawful filling of land exclusively with earth fill material that contains:no more than 10% organic matter or rubble by volume; and no object larger than 12 inches in any dimension. City Code, 1976/83, art. 11, §§221(a)(2nd cl.), 221(1), 224 Ord. 99-548