Chipotle is coming to 1512 Walnut St., the former Susanna Foo at Walnut and Sydenham Streets, and a company rep has announced that the first burrritos will come off the line on Oct. 20.

Chipotle has changed its corporate M.O., as it is not giving away free burritos on its opening day. It's doing a Halloween promotion tied to charity.

The arrival of a rival was not lost on Qdoba Mexican Grill, which recently remodeled its shop down the block at 1528 Walnut St.

On Saturday (10/9), this Qdoba is marking a grand reopening, handing out free food to the first 100 guests. Doors open at 11 a.m.

Back to Chipotle. On Halloweens past,  those who showed up, dressed up as a burrito or bag of taco chips, would get a free burrito. But this year, Chipotle's promotion is called "BOORITO 2010: The Horrors of Processed Food" and it runs between 6 p.m. and closing time. Those dressed up as a "horrific processed food item" get a burrito, in exchange for a $2 donation to chef Jamie Oliver's Food Revolution. Chipotle promises to donate up to $1 million to the cause. The chain also is running an online costume contest with cash prizes.

Oh, and which is better -- Chipotle or Qdoba ? Read this piece on the debate.