House on a hill, 400'+ from the street lateral. GC wants to horizontal drill sewer line. His question to me: If minimum slope is 2%, what is the maximum slope? Because of the slope of the hill, some of the grades between clean outs (100') could be as great or greater than 20%. My 2007 CPC does not address the issue. My experience is that it doesn't matter. But, I told him I'd ask for 2nd opinions.