I am not a city folk by any means, but I have never heard of having the drainage pipe open on the end and having fluid running out into the open. I grew up on a septic system, I also have one now and the drain field has always been completely underground. So, if you cap off the pipe, it would just be like all the systems that I am familiar with. I would think that the water would be forced out the holes in the pipe. Maybe I am missing something here...I would like to hear more comments on this.