Active job

Retaining Wall(s) for Slip Damage

According to my insurers I need the following: 1. One12 m long, 2m high wall with 13 bored, concreted encased SED275mm SED timber poles spaced at 1m. Pole length 6m with 4m below ground and timber lagged 150mm x 50mm. 100mm diameter sleeved perforated drainage pipe to be connected to a stormwater outlet., 2. One 8m long, 2m high wall with same materials as above. Both walls will need backfilling with free draining aggregate and soil. What I need to know is if I need both of these walls. As photos will show there is a spa pool area that can be removed if possible to save costs and I am happy to plant out the slip to prevent further movement. The slip itself hasn't moved significantly since the Anniversary Weekend floods and given the rainfall we have had I don't think it will. I would like a retaining wall against the house and steps to the upper level if possible but am open to suggestions. I need the job completed by the end of autumn next year, preferably earlier.