A city produces 1000 cubic meters of domestic garbage every day on average (calculated by compressed volume). It wants to build a landfill, dig out the garbage and bury it, and then cover the surface with a layer of soil with a thickness of one meter to restore vegetation. Decisions on equipment purchase and land requisition need to be made in the construction budget. Considering the economic problems of purchasing excavation and landfill equipment and land expropriation, the municipal authorities hope to give the least budget. The following situations are known:

1. Unearthed earthwork can be used for construction projects without treatment, but it must be transported to the ground and reserved for landfill cover.

2. The purchase cost of each set of excavation and landfill machinery is 6.5438+0.5 million yuan, and the service life is ten years.

The landfill is expected to be used for 50 years.

4. The compressed garbage is directly thrown into the garbage pit by the car without doing work.

5. The current land acquisition cost is 200,000 yuan/mu. According to statistics, the average increase of land price in the first three years was 10%/ year.

6. Diesel oil for machinery, with an efficiency of 30%. When working on flat ground, it takes 100KJ to move one cubic meter of soil, but with the increase of excavation depth, the efficiency decreases on the original basis 10%.

7. At present, the annual interest rate of bank loans is 5% and the deposit rate is 2%.

8. Landfill will be used for public welfare (such as establishing parks and green spaces).

According to the requirements of the municipal authorities, try to calculate the best excavation depth of the project and make plans and budgets for purchasing land and machinery.