In Austria everything flows into a big tank which is pumped regularly by some nice guys in a big truck, the contents are taken to the nearest sewage treatment plant. Beware if the cesspool overflows... i know a house where the basement was closed off for months after that happened, don't know how they cleaned it in the end.
Cost estimating: Sum up everything you might need in a project, add 20% safety, double that figure and add another 50% secret factor. The end result is likely going to be close enough. That's how they did it where I used to work. The HVAC planning guys 2 floors above didn't even bother to sum up everything they considered reasonable, instead they made something up that sounded good for the customer but in fact had no idea what they were doing until final planning stages when they did all the calculations.
