Hello I have a number of questions that you will need to look into before I can give you some definitive information. Have you contacted the utility company about the underground lines? Do they have a specific amount of space they need to keep open? How deep are the lines buried? Next, are you planning on working the area to increase drainage? A rain garden may not help if you plant in clay soil. With a path down the center, you will need to have 2 separate gardens. The Michigan Department of Environmental Quality has several good booklets on rain gardens. If you go to http://www.michigan.gov/deq then search "landscaping for water quality booklet", several booklets wil come up. The original is a design and plant resource booklet. Another is specific to designing your garden. Rain barrels come in different sizes and options. You will need to determine what you want the rain barrel to do. Then visit some stores or go online to look at what is available with the options you want/need. The most used rain barrel is approximately 50-60 gallons with a removable top and a spigot at the bottom. You may want to check into mosquito repellent tabs that get dropped in the water to repel them from breeding in the water. Also you may want to contact the Wayne County Extension office Horticulture Educator for more information. They can be reached at<personal data hidden>. Good luck!