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iv. Identify the locations of any hydraulic deficiencies(including components <br /> of the system with limiting capacity)that are generating Sanitary Sewer <br /> Discharges or Unauthorized Combined Sewer Discharges themselves. <br /> v. Identify the areas that are subject to chronic Property Backup incidents in <br /> both the Combined Sewer System and the Separate Sanitary Sewer <br /> System. <br /> vi. Determine the need for permanent flow meters to he installed and <br /> maintained at all sewer coru�ection points with sewerage owned and <br /> operated by SDD. <br /> d. An evaluation of the capacity of both the Combined Sewer System and the <br /> Separate Sanitary Sewer System. This capacity evaluation will include all major <br /> sewer lines, force mains,pump stations, all known overflow points,a11 areas with <br /> known chronic Property Backup issues, and any other portions of the both sewer <br /> systems that must be assessed so as to support a technically sound evaluation of <br /> all known causes of chronic Sanitary Sewer Discharges or chronic Unauthorized <br /> Combined Sewer Dischazges. The capaciry evaluation should specifically <br /> identify the hydraulic capacities of aforementioned portions of the sewer systems <br /> and compare those capacities to existina and future projected (through current <br /> year plus 20 years), average and peak,dry and wet weather. The capacity <br /> . evaluation will consider local rainfall data and the impact of an appropriate range <br /> of rainfa(1 events,based on return frequency and duration,on peak wet weather <br /> flows within Respondent's Combined Sewer System and Storm Sewer System. <br /> At a minimum the capacity evaluation should include the following: <br /> i. Average dry weather and peak dry weather flow data. <br /> ii. The followirig specified wet weather storm events: <br /> 1. 2-year/"critical duration" storm event <br /> 2. 5-year/"critical duration" storm event <br /> 3. 10-year/24-hour storm event <br /> 4. 10-year/"critical duration"storm event <br /> The"critical duration"means the duration of a specific return frequency <br /> storm event(e.g.,2-year, 5-year, 10-year)which creates the greatest <br /> stress on the sewer system, including the maximum surcharge and <br /> system outflow. The critical duration can he determined using flow <br /> monitoring data or modeling data. The critical duration is determined by <br /> comparing various durations of the specified storm and calculation the <br /> peak wet weather flow rate and volume of runoff for each. The duration <br /> resulting in the highest peak wet weather flow rate or largest total <br /> volume is the"critical duration"storm. The storms designed above shall <br /> be based upon the most current National Oceanic and Atmospheric <br /> Administration(NOAA) storm return frequency information for <br /> A3 � <br />