On Friday night and Saturday morning we got about 2.6 inches of steady rain, and there were small puddles of water that appear to have come from the NW back corner, the NE and SE front corners. (Since I don't live in the house yet, I was not there to see exactly where the water came from.) There are a number of anomalies that appear to be suspicious to me. Downspout drain pipes on the south side of the house are apparently clogged -- I ran a hose into the the SE downspout, and it caused a significant amount of water to go into the sump pump's inflow pipe, so I capped it off, and I have the water from that downspout running down what is mostly a very subtle slope from the frontyard to the street. The other southern downspout was in a window well, and when I ran a hose into that downspout's drain pipe, the window well became soggy. So I removed the downspout and capped off the drain pipe.
Also, I installed perforated drain pipes on the north and south sides of the house (about 2.5 feet from the house) to take advantage of what is generally a slight slope from the back of the house to the front yard and street. The idea of the pipes was to absorb large amounts of flowing water and take it from the back of the house to the street in the front yard. However, I wonder whether the pipes, which are covered with gravel are merely attracting water and that the water is somehow flowing to the base of the basement -- Following the Friday night and Saturday morning rain, there was virtually no standing water near the house, and the ground on the surface was not mushy. Also, I didn't see any water flow in the pipes shortly after the rain.
Finally, there are about twenty 1/2" diameter holes drilled through the basement floor that are spread all throughout the basement. I don't know why they are there, but maybe they have some effect on the flooding. Since, I don't live in the house yet, I can't say whether any water is coming up through them or not.
On the basis of this situation, I am puzzled as to why the basement is leaking. If someone could give me their ideas as how the leaks are coming about and how to fix the problem, it would be greatly appreciated.