Storm Sewer Design. A. Determine drainage areas, runoff characteristics, and 10-year and 100-year peak flow rates to all proposed inlets and pipes in the project area. Storm sewer design calculations and hydraulic grade line (HGL) calculations for the proposed pipe improvements for the 10-year and 100-year storm events. It is assumed that all existing storm sewer alignments will be followed, except for Site 1 that explore an alternative alignment across West 97th Street to potentially eliminate the diagonal crossing. Gutter spread calculations will be performed adjacent to the proposed replacement inlets. No drainage calculations are assumed for the additional bridge sites.
Storm Sewer Design. Provide a separate storm and sanitary sewer system by incorporating all stormwater in a new system. New storm system will be designed to handle the 10 year storm and will be checked using the 50 year storm (HGL to remain below the rim elevations). Also the inlet spacing will be designed so that the maximum spread does not encroach more than four feet into the travel lane. The old combined system will remain as a sanitary sewer and no changes will be made to that system other than adjusting the casting elevations as needed to match the proposed grade. All drainage from the project site will flow to the west and will be connected to an existing storm system located in the northeast corner of the intersection of Northwestern Avenue and Xxxxxxxx Road. This existing storm sewer crosses under Northwestern Avenue and connects to an existing drainage basin located in the northwest corner of Northwestern Avenue and Xxxxxxxx Road intersection. As per previous discussions with the City of West Lafayette, it is assumed that this existing storm system and drainage basin are designed to handle additional flow from Xxxxxxxx Road reconstruction and, therefore, no changes are anticipated to the existing storm system crossing under Northwestern and the existing drainage basin.
Storm Sewer Design. The Engineer shall design all conventional storm sewer drainage in conformance with the latest edition TxDOT’s Hydraulic Design Manual, Districts’ criteria, and any specific guidance provided by the State, and as follows:
Storm Sewer Design. No storm sewer design will be completed with this project other than sizing RCB crossing.
