I would split the audio recording into two sections. Firstly using the mics described get as clean as possible voices for your interviews, move the person/people you want to interview to a relatively quiet part of the building site (if possible) and when you are done with that, then record a wildtrack (how long is your building site piece anyway?) Well, whatever length it is record enough wildtrack to cover the entire piece to give you more choices at the editing stage. This means you will have two audio tracks, the interview voices and the wildtrack that you can play at a lower volume when you need to hear someone speaking. If you want to add visual variety to your interviews use the Insert Edit technique, to show what the interviewee is talking about rather than just a talking head onscreen for whatever number of minutes.

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Better than a poke in the eye with a pointy stick any day...