The original plan was to join the sewer about where the black car is in the photo. That would be a 45m sewer run but the 37cm difference in the required invert is actually a really big deal. A sewer laid at a minimum fall of 1:80 would require a further 29.6m of horizontal run but Sydenham Road isn't long enough. Fortuntely there was some contingency in the measuring but this meant a further 10m of excavation at a cost to me of £2,400. The final run will be 56m long. So thats £3.42 per centimeter!