Hi I am about to do some underpinning to create a 9' basement under a 1907 victorian in San Francisco. I have done underpinning several times before and have had access to waterproof and put in a french drain on these jobs and then back fill etc... On this job there is only 10 inches between the neighbors building and in that space there is a concrete slab with a swale that diverts water effectively. However I am still seeing some evidence of moisture in the dirt I have excavated so far. My question is since I will be underpinning and only in 4' sections and using the soil as the back form what product or method of waterproofing is available? I could put in an interior "french drain with a sump but I don't really think that is practical. Any thoughts?