A Gardnerville couple is facing mandatory prison on allegations that they sold methamphetamine, and kept their drug supply within reach of their two young children.Roberto Rodriguez, 25, is charged with two counts of trafficking in a controlled substance, methamphetamine; two counts of allowing a child to be present in the commission of a controlled substance violation; and two counts of sales of a controlled substance.His girlfriend, Michelle A. Hart, 22, is charged with child endangerment and trafficking in a controlled substance.According to court documents, the pair was arrested following a three-month investigation by the Douglas County Sheriff's Office investigators which …