Starting Monday, with the arrival of CTrail train service from Springfield to Hartford and New Haven, commuters will be able to park in Springfield Union Station’s parking deck for $5 a day. And starting in July, they’ll be able to park in the Union Station garage for $65 a month, according to a news release issued Wednesday. Parking at Union Station will be free this Saturday and Sunday when CTrail offers free trips as a way to introduce folks to the service. Local officials, including U.S. Rep. Richard E. Neal, D-Springfield, will take a ceremonial ride Friday. The old Union Station parking garage rates are $1.50 for the first half-hour, $2 for each additional hour and $50 a week, according to the Springfield Parking Authority.