Recent successful CIPP lining of a CMP culvert led to an interest in determining the hydraulic characteristics of the lined culverts. Measurements of the CIPP liner's wall-roughness and cross-sectional geometry permitted development of a preliminary evaluation of the hydraulic performance of the CIPP lined pipes. The overall approach was to compare the hydraulic characteristics of the CIPP-lined and the host-CMP culverts. First, we established the important geometric properties of the CIPP and CMP barrels that influence culvert hydraulics including their Manning's roughness. Next, we compared the hydraulic performance of the culverts during projected 100-yr peak flow conditions in the creek. Last, we evaluated how the geometric changes in the culvert (reduced cross section and reduced surface roughness) can be expected to influence hydraulic performance of the barrel when flowing full under outlet control conditions. This research concluded that CIPP lining reduced the cross sectional area and height of the barrel opening of the CMP culvert, however, produced a significantly lower roughness than the recommended value for the original CMP culvert. At the design flow (850-cfs) the hydraulics of culverts are governed by outlet control. This results in headwater depths that reflect the energy losses through the barrel of the culvert. The dominant effect of the CIPP liner in this regard is that reduced roughness lowered the headwater depths. This paper presents the details and conclusions of this important hydraulic analysis.
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