A mini excavator can dig between 5 and 11 feet deep, depending on the type and size of the mini excavator. Mini hydraulic excavators are more powerful and can reach deeper into the earth, but electric models have a more limited range. Mini excavators over two tons in size are also more powerful and able to dig as deep as 11 feet.

The physical constraints of hand-drilling a well limit the depth you can achieve. Manually digging with picks and shovels may only lead to shallow wells of up to 60 feet in depth. To reach greater depths, you need more specialized equipment. The diameter of your well and the tools you’re using will determine how far down you can dig.

Septic drain lines (or leach lines) are typically buried between 18 and 36 inches underground, and should be at least 6 inches below the surface. These pipes are perforated and surrounded by filtering materials like sand or gravel. Burying the lines at this depth helps minimize odors and allows bacteria and other biological processes in the soil to effectively treat the wastewater. Burying lines too close to the surface can cause issues unless the soil is very compact and stable.

If you don’t have a crawl space but have a partial basement you want to make deeper, you can expect to spend a little less—between $40,000 and $90,000 on average. However, if you’re not adding new finished square footage, you won’t see much in the way of ROI.