It looks to me like you’ve got a couple things to consider: security and form setup.
Setup: If the form should only include venues for Alexandria, make it a pulldown and include only “Alexandria” as an option. Either that, or don’t even offer the venue city and venue state. What’s the point if it must always be in Alexandria anyway? Narrow the form options to only those that are appropriate to your venue.
Security: Database their answers and include a contact email address and phone. Add a second step where they receive an email that includes a confirmation link. Once the confirmation link is clicked by them, add a third step that emails or IM’s you with a link to accept or reject the new venue. This way, you get only valuable information on your site, and you have control in three steps as to who can actually post a new venue or not.
Include an administrative back end for yourself so you can delete, edit or preview each venue.
For any that seem on the fence, call the phone number to verify and ask for more information. If the number is bogus, delete the venue before it even shows on your site. If the person sounds like they know what they’re talking about, accept the venue and it will be published.