That's fantastic!
Here are some general tips for you to prepare for your media interview:
1. Prepare, prepare, prepare. Have facts and stats specific to your project written down and at your fingertips. Bring an extra copy to leave with the reporter (assuming you're doing this in person) or e-mail a copy to the reporter in advance of the interview. Cite sources for your facts and statistics. If you've got a record of the mayor's behavior (including dates, what happened, your attempts to follow up, etc.), that's even better -- bring/send that, too.
Also, prepare for questions that may seem hostile, but are really just trying to get at the heart of the matter. For example, "Why should the city spend money on this project when there are so many other needs?" etc. Though this type of question may sound confrontational or mean, it's actually trying to get you to give your best arguments in favor of your project in print. These are the questions some readers might be asking, and the reporter is trying to cover all the angles.
Also remember they will probably try to contact the mayor for comment, so prepare any responses you can think of to arguments the mayor might make and say them in the interview.
2. Talk about the most important stuff first.The reporter might be on a tight timeline. Make sure you get your most important points up front. Have them practiced in short, snappy sentences. Your key points should highlight why this playground is important, how many kids will be served by it, etc. If you feel the interview is diverting from the important stuff, you can bring it back by using phrases like, "Well, the important thing to remember here is..." and then go back to your main points.
3. If you don't know the answer to a question, say "I don't know" and offer to get back to the reporter by a specific time with the answer, if you think you can find it. Or point them toward someone who does know.
4. Remember, nothing is ever "off the record!" Anything you say can be used in print.
5. It's OK to bring notes! Especially if you leave those notes with the reporter!
I'm sure there's lots more wisdom out there people can share. Anyone else have some great media tips for Sammy12?
Good luck!