The cost of drainage system will be depreciated over 15 years. You will enter it as an Asset through your Rental Income and Expenses section.
As you go through the screens adding the asset, select Rental Real Estate Property > Land Improvements. When you get to the question about using the asset 100% for business, you answer 'no' and follow the guidance to adjust for personal time spent at the property.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"