It may possible I have pasted the staute with the requirements below;
because the plea is what you will be vacating and not a dui you may be eligible read the rules and find a criminal defense attorney in your neighborhood.
Good Luck and drive safely
Generally speaking, it appears you are eligible to vacate the Neg1. You must meet the following conditions and the Court does have discretion on whether to grant the motion or not.
• It has been at least three years since you completed the terms and conditions of the sentence, including restitution/legal financial obligations. (since the case was closed)
• There are no criminal charges pending against you in any court of this state or another state, or in any federal court
• You have not been convicted of any new crime in this state, another state, or federal court since you was convicted in this matter.
• You have never had the record of another conviction vacated.
• You are not currently and have not been restrained within the last five years by a domestic violence protection order, a no-contact order, an antiharassment protection order, or a civil restraining order which restrains one party from contacting the other party.
See this link for more information: http://www.courts.wa.gov/forms/index.cfm?fa=forms.contribute&formID=38