Thanks to everyone for the various comments and suggestions and leads into books and tables. It looks like analysis supports the idea of a 6 inch pipe. The incremental cost over a 4 inch pipe I now also have some specific information for the excavator on a minimum slope for the first 30 feet...
We have looked at the problem in terms of trying to stop water from getting under the house in the first place. After lots of discussion as well as free and unsolicited informed and uninformed advice :-), we have come down to improving the flow out of the sump pit as the lowest cost and most...
This summer our basement flooded with about 12 inches of water. We have two sumps that basically got overwhelmed for several hours. Since we live on a steep hill that had a notch cut out for the house, my intent is to have a contractor dig down and install a gravity drain from the bottom of...
