August 1, 2010 is a day that many Southwest Airlines Business Select fliers know well. It’s the day on which the carrier stopped allowing these passengers to carry over their unused free drink vouchers to future flights. More than two years and one class-action settlement later, Southwest is having to buy a lot of rounds.

We first wrote about the lawsuit last November, when a Southwest Business Select passenger from Chicago alleged the airline unjustly enriched itself by effectively voiding millions of dollars worth of drink coupons that these customers had not used by the Aug. 1, 2010 date. The named plaintiff in the case had 45 of these vouchers (worth around $5 each) in his possession at the time the policy went into effect.

While Southwest will not be changing its policy back — Business Select passengers must still use their voucher on the day of the flight for which the voucher is given — the Chicago Tribune reports that Southwest passengers who earned these vouchers before the 10/1/2010 date get new vouchers from the airline. These vouchers will need to be used within one year of being issued.

Since many people no longer have those old, useless vouchers, Southwest will be identifying and notifying eligible travelers in the coming weeks. It will also be setting up a website for affected customers.

The current estimate for the number of vouchers that will be issued is around 5.8 million, which translates to $29 million in free drinks.

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