@classmethod
def _normilise_barehole(cls, bareholes):
    """Normalise 5+ meters bareholes to 5 meters."""
    count = 0
    new_bareholes = {}
    for key in bareholes:
        if key >= 5:
            count += bareholes[key]
        else:
            new_bareholes[key] = bareholes[key]
    if count:
        new_bareholes[5] = count
    return new_bareholes
