Got a call today from a woman that has drainage issues in her back yard. I went and checked it out, the yard is pretty flat, a few low spots but not bad (2"-3" low at most). These low spots of course collect water, but as I walked the property I discovered the whole yard holds water. Both neighbors have had drainage systems installed, the house behind hers is a slight hill (I'd contribute this to the problem) so they don't have a problem. I took a couple of plugs out of the ground, 8" deep, the soil isn't hard clay, but its typical soil for ohio. The turf is starting to take a serious beating from all the water too. I expected the ground would be frozen (my yard is) yet here the ground is mush in most spots. The very back of the yard is so bad that I was standing there and sunk about an inch and displaced little pools of water around my shoes. So this is a very bad spot. I have alittle knowledge on drainage systems, but never have done a large system. The back yard is 19,500 sq ft.... So this is going to be a big job. The good part is, theres a storm sewer on the one edge of the property in the center of the yard. So i have somewhere to drain to. Now for my questions. On a job this size, how would you run all the piping? How many pipes would I need to install? Like I said, the whole yard gets water, she said the middle of the yard will hold a pool of water if it rains hard enough, so its going to need piping through out the whole back yard. I planned on running it from side to side of the yard and would need mutliple rows....I'm just not sure how close or how many rows i'd need to achieve proper drainage. Any help would be appreciated.