Acid rock drainage has recently been a hindrance to the completion of the construction of Interstate 99 near State College, Pennsylvania. However, this acid rock drainage didn't come from a mine; rather, it was produced by oxidation of pyrite-rich rock which was unearthed during a road cut and then used as filler material in the I-99 construction. Similar issues with pyritic slate occurred at the Halifax Stanfield International Airport in Canada. When the phenomena is the result of earth-moving operations other than mining it is sometimes called "acid "rock" drainage"".