The normal rule in a situation like this is called "cover." That is
to say that you do what you can to reduce or eliminate any damages
you may incur, and then ask the seller to reimburse you for the costs
of doing that. In your case that might be to rent another backhoe to
do the work, if you can. Are there other ways to get the same work
done?
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Stu
http://DownToEarthLawyer.com