¹HDR Engineering.
²CH2M Hill.
³City of Omaha.

Abstract
The City of Omaha initiated development of a Combined Sewer Overflow (CSO) Long Term Control Plan (LTCP), which required public involvement for a successful program. The combined sewer system area was divided into 10 basins for evaluation. With these 10 basins and seven Basin Consultants analyzing alternatives, the Program Management Team initiated a detailed decision process involving community input to maintain continuity for engaging the public in the alternative selection process. The integrated decision process approach involved groups of individuals from the public to serve on advisory panels for each of the 10 basins and one group to serve as a program-wide advisory panel. These advisory groups identified key criteria and associated weights for the criteria for selection of alternatives through public workshops and meetings from October 2006 through June 2007. With this integrated approach, alternatives identified at the basin level were effectively compiled into the system-wide LTCP.

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Atlanta’s Comprehensive Approach to QA/QC in SSES and Rehabilitation Design

Hatem K. Elsayegh¹*, Raymond E. Hutchinson², Latasha Norris³

¹Jordan Jones and Goulding, Inc.
²Montgomery Watson Harza
³Department of Watershed Management, City of Atlanta

Abstract
The Clean Water Atlanta sewer system improvement program is one of the most comprehensive programs of its kind in the U.S. 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 that the City of Atlanta perform improvements to the approximately 1900 miles of sanitary and combined sewer collection system. The main objectives of the consent decrees are the reduction of 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 focus of this paper is the QA/QC process followed in SSES and Rehabilitation & Replacement Design.

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Application of Continuous Simulations to Separate Sanitary Sewer System Planning

Gunilla Goulding, PE¹*, Constance Kepner²

¹Malcolm Pirnie, Inc.
²Butler County Department of Environmental Services (BCDES)

Abstract
The use of continuous simulations in conjunction with design storms for separate sanitary sewer master planning is a wet-weather analysis approach gaining favor in applications where more rigorous verifications of facility sizes are desired or storage options are viable. However, the benefits of continuous simulations should be weighed against the effort required to perform these simulations. This paper discusses the issues and results of using continuous simulations for separate sanitary sewer master planning through two case studies, and then summarizes lessons learned for other utilities considering the same decision.

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The Evolution of the Small Diameter Variable Gradient Sanitary Collection System into the Small Bore Sewer™

Jill Lauren Hass¹

¹Wastewater Systems Division of Clearford Industries, Inc.

Abstract
During extended periods of wet weather and storm events, large volumes of groundwater and surface water can infiltrate typical sanitary collection systems, resulting in design requirements to oversize the piping network. Affordable and cost-effective sewage collection systems that maintain or improve environmental protection are often sought out by municipalities and design engineers; however, traditional gravity sewers typically allow excessive amounts of infiltration and inflow (I/I) to enter into the sewer network, overwhelming the treatment plant with surges of diluted sewage and leading to requirements for bypass of the treatment process. The evolution of the small diameter variable gradient (SDVG) sanitary collection system into the watertight Small Bore Sewer™ (SBS™) system has proven that removal of inflow/infiltration and removal of sewage solids at source can eliminate bypass occurrences and reduce the downstream wastewater treatment plant requirements and operation and maintenance costs.

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Technical Challenges and Community Acceptance in Designing One of North Carolina’s Largest Sewers

Laurin B. Kennedy¹*, George Jones², Jeffrey F. Payne1

¹ CDM.
² Charlotte-Mecklenburg Utilities.

Abstract
Charlotte-Mecklenburg Utilities (Utilities) currently operates five wastewater treatment plants (WWTPs) with a combined wastewater treatment capacity of 118 mgd. The existing Briar Creek trunk sewer was constructed of vitrified clay pipe (VCP) in the late 1920s, and the condition and capacity of the existing sewer does not provide the level of service required by Utilities, new state laws, and EPA. When the proposed design of the new relief sewer was introduced to the public, there was significant public opposition. Because of the vocal public opposition and concern over the project, a proactive public communication and outreach program was developed that gave property owners multiple opportunities to provide input. As a result, the route was realigned to reduce impacts to residential properties by 50%. As a result of the proactive public communications program, public opposition was significantly reduced, and all of the 63 easements for the project have been acquired.

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Long-Term Cured-In-Place Pipe (CIPP) Performance and its Design Implications

Robert K. Lee¹*, Steve Ferry²

¹ Malcolm Pirnie, Inc.
²Hauser Laboratories.

Abstract
Cured-in-place pipe (CIPP) lining is an attractive alternative for rehabilitating pipes without the need for digging. However, the nature of CIPP is, in essence, a pipe manufactured below ground. And unlike pre-fabricated materials that have been through a series of long-term testing, below ground “manufacturing” introduces a host of variables (variable installation conditions, different installation methodologies, etc.) in the short and long-term reliability of CIPP as a pipe material. Contractors, engineers, and utility owners have generally accepted that CIPP has a 50-year design life and most CIPP designs assume that the long-term properties of the liners will retain 50% of their initial value. This paper addresses the various ways to test and anticipate the long-term performance of CIPP liners and verify the true design life. The paper also presents options available to Owners and Engineers if test results are not as expected.

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Effective Flow Metering and Reporting Through Remote Network Management and Automation

Mark Huber¹*, Tom Luking²

¹Huntsville, AL Water Pollution Control Department.
²Tetra Tech, Inc.

Abstract
The City of Huntsville, Alabama’s Water Pollution Control Department has taken a proactive approach to Management, Operations, and Maintenance (MOM) of their collection system. One aspect of the approach was to create an automated permanent flow monitoring program. This approach to flow monitoring allows WPC to manage the flow monitoring network remotely through a hard wired system to reduce flow monitoring and reporting costs, improve collection system performance through timely identification of blockages and other conditions affecting the system’s performance, collect extensive data related to system performance over time, and program investigations and other Inflow and Infiltration (I&I) reduction activities in a fiscally responsible manner. WPC built this system using only off the shelf software and has ultimately realized a substantial cost reduction for flow monitoring when compared to “blind” permanent or temporary metering.

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A Comparison of Methods and a Simple Empirical Solution to Quantifying Base Infiltration in Sewers

Paul S. Mitchell,¹* Patrick L. Stevens¹ and Adam Nazaroff²

¹ ADS Environmental Services
² Orange County Sanitation District

Abstract
This paper addresses three empirical prediction methods used to estimate the magnitude of Base Infiltration (BI) in 45 isolated sewer basins throughout the Orange County Sanitation District (OCSD) collection system: night-time “Wastewater Production”, “Minimum Flow Factor”, and a third empirical method employing the “Stevens-Schutzbach” equation. These empirical methods were tested against a chemical parameter verification method that involves regressing hourly concentrations of several common wastewater chemical analysis parameters (Chemical Oxygen Demand – COD, etc.) with hourly sewage flow rates. The chemical parameter method results were also compared to BI estimates based on potable water use records. In addition the Wastewater Production and Stevens-Schutzbach methods were evaluated by comparing the BI predictions to the sewer flows during the Northeast Power Blackout of 2003. Results indicate that the Stevens-Schutzbach equation provides a more accurate estimate of BI in basins yielding flows comprised of more than 20% BI.

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Planning Level Cost Estimation for Sustainable I/I Reduction Using a Performance-based Cost Function

David Perry¹, Andrew Lukas¹, David Bennett¹, Timothy Bate², William Krill³

¹ Brown and Caldwell, 250 East Wisconsin Avenue, Suite 1525 Milwaukee, WI 53202.
² Milwaukee Metropolitan Sewerage District.
³HNTB.

Abstract
This paper presents an alternative approach to estimating the cost of I/I reduction that is not technology dependent because it is based on performance results from a wide range of I/I reduction projects. The Water Environment Research Foundation (WERF 2003) documented demonstration projects; the study reports the I/I reduction achieved and the cost. These projects along with other available I/I project experiences from Milwaukee, Wisconsin and King County, Washington were used to create a performance based cost function for the unit cost of I/I removed based on pre-rehabilitation I/I rates. Experience from the Milwaukee Metropolitan Sewerage District shows how the approach has been applied to determine the cost of I/I reduction for sustainable facilities planning. This method can be applied to overall system master planning as well as preliminary planning of smaller conveyance upgrades projects.

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Developing Criteria for Design Event Selection

Nancy U. Schultz¹*, Richard E. Nelson¹

¹CH2M HILL.

Abstract
Design flows for separate sanitary sewers have evolved from steady-state, constant flows calculated from the number of connected fixtures connected to complex dynamic calculation based on storm conditions and expected, although often illicit, interconnections with the storm drainage system. This paper will examine the historical evolution of the theory behind defined design flow conditions through the selection of specific design storm conditions. Design criteria should consider both flow generation rates from customers and system leaks and the level of service to be afforded customers. To a great extent, the current frequency of SSOs being experienced by some systems is due to the use of past design criteria that did not adequately address flow generation rates or level of service. A recommended decision flow chart for selecting design storm conditions for sanitary sewer systems subject to rainfall derived infiltration inflow is presented.

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Developing a Typical Rainfall Period for Long Term CSO Analysis in San Francisco, California

Sharon Tsay¹*, Dominique Brocard¹, Wallis Lee², Greg Braswell²

¹Metcalf and & Eddy
²Bureau of Engineering, Department of Public Works, City of San Francisco

Abstract
This paper describes the selection and development of a 5-year rainfall period that is currently being used by the City of San Francisco to evaluate sewer flows in a collection system model. The analysis addresses issues such as global climate change and spatial variation during storm events. The long-term rainfall was developed by selecting a 5-year period that closely matched average rainfall records for the past 30 years. The 5-year period was modified by adding and removing storm events to further improve the match to average conditions. The typical period was used to simulate overflows using a calibrated InfoWorks CS model of the San Francisco collection system. The resulting overflows were compared to the numbers that have been reported by the City for the past 20 years. The results of the model simulation indicate that the typical 5-year period closely reflects average overflow performance.

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Implementation of an Offline Storage Facility in Washington Suburban Sanitary Commission’s Dynamic Hydraulic Sewer System Model

Matthias Wittenberg¹, William A. Barrack II², Kenneth C. Dixon³*, Craig A. Fricke³

¹McKissack & McKissack of Washington, Inc., 1401 New York Avenue NW, Suite 900, Washington, D.C. 20005
²Camp Dresser and McKee, Inc., 3130 Fairview Park Drive, Suite 400, Falls Church, Virginia 22042
³Washington Suburban Sanitary Commission, 14501 Sweitzer Lane, Laurel, Maryland 20707

Abstract
A baseline dynamic hydraulic sewer model was developed for the Washington Sanitary Suburban Commission’s (WSSC) Rock Creek Sewer Basin using Wallingford’s InfoWorks CS program. The sewer system model was used to assess the existing and long-term capacity of the sanitary sewer system and simulate the operation of the Rock Creek Storage Facility. The facility allows WSSC to limit peak wet weather discharges at the basin boundary to an agreed limit. The results showed that the current operational procedures are effective in limiting the flows at the basin boundary though they may result in using the facility more frequently than necessary. Filling the available storage volume early during a storm event caused the storage volume to be unavailable for subsequent storm events. The modeling of alternative operational scenarios resulted in refined procedures that improve the operation of the storage facility.

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