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Logarithmic sensitivities and plausible relative errors are studied in a simple no-crossflow model of a transient flowmeter test (TFMT). This model is identical to the model of a constant-rate pumping test conducted on a fully penetrating well with wellbore storage, surrounded by a thick skin zone, and situated in a homogeneous confined aquifer. The sensitivities of wellbore drawdown and wellface flowrate to aquifer and skin parameters are independent of the pumping rate. However, the plausible relative errors in the aquifer and skin parameters estimated from drawdown and wellface flowrate data can be proportionally decreased by increasing the pumping rate. The plausible relative errors vary by many orders of magnitude from the beginning of the TFMT. The practically important flowrate and drawdown measurements in this test, for which the plausible relative errors vary by less than one order of magnitude from the minimum plausible relative errors, can begin approximately when the dimensionless wellface flowrate exceeds q D ¼ q=Q % 0:4. During most of this stage of the test, the plausible relative errors in aquifer hydraulic conductivity (K a ) are generally an order of magnitude smaller than those in aquifer specific storativity. The plausible relative errors in the skin hydraulic conductivity (K s ) are generally larger than the plausible relative errors in the aquifer specific storativity when the thick skin is normal (K s > K a ) and smaller when the thick skin is damaged (K s < K a ). The specific storativity of the skin zone would be so biased that one should not even attempt to estimate it from the TFMT.

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The Clean Water Atlanta sewer system improvement program is one of the most comprehensive programs in the U.S. where the entire public sewer system with diameters 8 inches and larger is being evaluated and improved. The program received its mandate from the Consent Decree (concerning the combined system) and the First Amended Consent Decree (concerning the sanitary system) which require the City of Atlanta to perform significant improvements to it's approximately 1900 miles of sanitary and combined sewer collection system. The main objective of the consent decrees is to reduce the frequency of combined sewer overflows and the elimination of the capacity and maintenance related sanitary sewer overflows. The total cost of the program is expected to exceed $2 billion, of which approximately $900 million is budgeted for SSES, rehabilitation, sewer cleaning and flow monitoring.The program contains many tasks but four in particular are geared to the rehabilitation program and are very closely linked. These include: Sewer System Evaluation Survey (SSES), Hydraulic Modeling, GIS, and Sewer Rehabilitation Design.The City of Atlanta sewer system is divided into ten sewer basins which discharge to one of four major wastewater treatment plants. Each sewer basin is further divided into sewersheds containing 25 to 50 thousand feet of sewer which in turn discharge through a single outfall sewer into the system. A total of 260 sewersheds constitute the City of Atlanta sewer system.The size of Atlanta's sewer system and the task interdependence both underscore the need for a comprehensive and robust quality control and quality assurance procedure at each step. The focus of this paper is the QA/QC process followed in SSES and Rehabilitation & Replacement Design.

Getting a handle on your sanitary sewer system and the potential impacts of spills on local waterways, maintenance costs, and frequency of repairs is a challenge for any system, especially if you're trying to take a more proactive approach to operations and maintenance. One metro Atlanta system learned this first hand when it implemented a prioritization plan for performing a Sanitary Sewer Evaluation Survey (SSES) for all of its 35 sub-basins. With approximately 2,400 miles of sewer and 61,000 manholes in 35 sewersheds, the DeKalb County (GA) Department of Watershed Management took on this challenge in 2008. Parameters for the prioritization plan included: -Rain Derived Inflow and Infiltration (RDII) -Field Inspection Reports -Frequency of reactive maintenance -Frequency of service-related maintenance -Frequency of structural-related maintenanceWater features were also considered in order to capture the risk of polluting water bodies in case of pipe failure and consequent spills. Initially, each parameter was scored differently, e.g. using count of structural and service defects and value of peak to average ratio for RDII. To ensure that scores are independent of basin size, all scores were divided by the total linear footage of sewer in the respective basin. Furthermore, the scores were also normalized to a scale of 10 so they can be compared equally across the different parameters. For each parameter, the basin with the highest overall value received a score of 10. All other basins were rated relative to the basin with the highest score.After the scores were normalized across basins and across parameters, weights were used to emphasize importance of certain parameters relative to others based on interviews with county staff.Two sets of rankings were used: the first ranking is based on the priority of inspecting each subbasin within its respective basin, thus spreading the work geographically. The second ranking is 560 Collection Systems 2010 based on inspecting the worst sub-basins over the entire county. While the ranking within basin helps county staff work simultaneously in different areas while focusing on the highest priority areas, the overall ranking provides the opportunity to work on the highest priority areas regardless of their proximity to each other.