Additional founding costs / Civil engineering costs

Hello everyone,

I am about to have the notary appointment for a plot of land, but the soil report is rather sobering. If the costs now escalate, I would decide against the property and prefer the famous lesser evil (costs notary and soil report = 1,000€). I would be interested in your assessment regarding the expected costs for earthworks / civil engineering.

It is about a plot of approximately 700 sqm in Brandenburg.

[*]Soil condition: 1.10m fill (compacted rubble with sand and brick rubble, coal residues, etc.), not contaminated with heavy metals, pesticides, or similar (there is an existing soil analysis / contamination investigation of the entire parcel). Soil class Z 1.1 and Z 1.2. Underneath these 1.1m of fill it is OK and load-bearing.
[*]Planned are 115 sqm excavation pit for house and 35 sqm excavation pit for garage
[*]550 sqm garden (initially only lawn planned)
[*]Service trench 20m
[*]No basement
[*]Water protection area, so no use of recycled material for backfilling possible.
[*]Plot and street are at the same level.

The soil must be removed at least for the excavation pits of the house and garage (the 1.10m). Possibly alternative strip foundations? For the driveway, the current surface is probably OK. The soil expert inspected this on Friday, written report will come next Wednesday.

So what is needed:

[*]Excavation and removal of excavation pits house and garage 165 cbm (115+35 sqm x 1.1m) including disposal costs => Are 5,000€ realistic? If shares of soil class Z2 are found: What does this usually cost?
[*]Backfilling (filling sand? Gravel / crushed stone?) and compacting 165 cbm x compaction factor 1.5 = 250 cbm => Are 10,000€ realistic?

Can I alternatively save something with strip foundations for the excavation pits house and garage?

Besides that I am expecting:

[*](Sieved?) topsoil for garden: 550 sqm x 0.4m (?) = 220 cbm x 20€ = 4,400€? This would raise the plot by (in this example) 0.4m. Should be OK, right? The slab will be higher anyway, I assume. I did not want the garden to be excavated but instead supplemented according to the soil analysis.
[*]Budget for rainwater drainage (no soakaway allowed => 3,000€?)
[*]Digging service trench 20m (house is to be located far back) plus disposal => 2,000€?
[*]A house pumping station is supposed to cost 3,500€ (wastewater has to overcome a slope)
[*]Connection costs, terrace, paving etc. in any case extra

Apart from this, of course, the question arises whether one wants a garden on a rubble pile, but I still have to consider that.

Looking forward to your feedback!

Best regards