An old home I intend to buy has a basement under the frony half and a crawlspace under the back half. The house is on a slope which slants from back to front. Along the back of the house and one of the sides is a 20 inch wide trench ( which exposes the foundation of the crawlspace) then there's a 2ft high cement retaining wall flanking the trench as you move away from the house(which is cracked and leaning toward the trench- toward the house. The trench does not continue on the other side of the house, or the front which is mostly out of the ground anyway due to the slope. However,the basement is quite damp. There are heavy calcium deposits inside the basement on the non-trenched side. I don't quite understand the purpose of the trench and would like to eliminate the unsightly ,broken retaining wall as well as prevent the moisture in the basement. What should I do?