An existing 24 inches concrete sewer pipe currently serves a small town but is expected to be under capacity when the population peaks at 300,000 . The existing line drops 100ft as it travels 4000ft to the first pumping station. A second pipe will be installed in parallel to the existing pipe. Use 250 gpcd as an estimate for the future wastewater production. Assuming full-flow conditions, what diameter pipe in inches should be installed so that the combined capacity will be adequate for the peak population?