My house is an older bungalow, built in 1918. The basement walls were constructed with local river bed sand that is seriously losing its strength. The walls are crumbling in some places. I recently took a concrete foundations class, mostly thinking ahead for beach cabin construction, but got to thinking about repairing my basement walls. I was thinking about pouring new concrete walls next to the old that are seriously decaying, removing the old walls and repouring again in that spot. There would be double walls in part of the basement, but that's better than the current situation. I can't seem to find any books with ideas on how to repair such serious damage. Any thoughts or suggestions would be much appreciated.