I put no stock in this answer.

The Corps doesn't usually do much construction work themselves ("evil gubmint" or no "evil gubmint",...), the Corp, in most of my experiences, will do a procurement and hire a contractor to do any actual work on something like this. And, I'm not even sure why the Corp would be involved at all, with repair or replacement of he RR bridge. Except possibly from some kind of permitting and/or design issue to do with flood control associated with the waterway that's being bridged?

Now could the County contract through the Corp, in relation to other drainage related work to do with the waterway? Yes, that might be possible.

This answer just seems a wee bit "lite" on details, and there is nothing on the agency website about it, nor could I find any articles.