| he studied drainage system is located in the downtown of the City of Newport News, in a basin known as Anderson Park. The drainage system collects and conveys rainfall runoffs to the system outfall located at the shoreline of the Hampton Roads body of water, which is located south of the study area. The aim of this study is to analyze the area's drainage system, determine maximum capacities, identify system deficiencies and generate the most possible, practical and economical solution for fixing the system deficiencies.;After collecting all of required data, the drainage system was modeled and calibrated using the recorded rainfall data of October 9t11, 2013 and the measured watermark elevations at the selected junctions. The methods used for estimating probability distributions of the recorded rainfall frequency were Hazen, Weibull, Gringorten, and Sevruk & Geiger; and the Weibull method was used for the system analysis. However, the City's requirement is for all drainage systems, residential and commercial, to handle NOAA's 10-yr storm, which is the accumulation of 5 to 6 inches in 24-hour duration.;For the purpose of this study to include loss analysis, storm return periods from 10- to 500-yrs were listed and ranked to their rainfall depths and the associated damage values. To determine the severe cost of the drainage system improvement, the system was subjected to Weibull 100-yr storm.;This study tried to improve the drainage system by increasing pipe sizes to the minimum possible diameter that the system can handle the Weibull 10-yr storm flow without experiencing flooding anywhere along the system pipeline. For this purpose, the technique of optimization was utilized to perform pipe-area changes and to keep HGLs at or below structure rim elevations. Four improvement case scenarios were created at the targeted area along the drainage system where all branches merge together.;Finally, the selected case scenario 4 at... |
