Two methods of carrying away surface runoff water from a new subdivision are being evaluated. Method 1 – dig a ditch. This would cost $60,000 and would require $25,000 of re-digging and shaping every 5 years after. Method 2 – Lay concrete pipe. The first cost would be $150,000 and a replacement would be required at 50 year intervals at a net cost of $180,000 for each replacement. At I = 6%, which would be the better choice?