I have an old ( about 1850 ) cottage I'm doing up at the moment. We have the normal pipe arrangement from bathroom etc into a main soil stack which is vented above roof level. Also at the other end of the house is another stack coming from I assume the sewer run and venting above roof level ,it does not connect to any pipes. I'd like to remove it as it's unsightly and I've noticed many old houses round here have what look like 3/4 ft cast iron vents in their gardens,this pipe of mine may have replaced one. Anyway can I take it away and just rely on the main stack . Thank you.