Sounds like your problem has been solved. Another option however would have been an excavator mounted hydraulic rotary cutter. They come in a range of size classes from mini-excavators to the big daddys.
These can be rented. They are nice because they can cut very precisely. They also come...
You may want to consider an excavator mounted cutter head or cutter bucket. These are catching on in Europe and are just starting to be used in the US. These cutters are nice because a much narrower trench width can be excavated which reduces backfill volume. They also have lower noise and...