Austin gears up: to solve wastewater problems.
The city of Austin is the capital of the state of Texas and home to the University of Texas, the country's largest public university. It is a community of nearly 700,000 people. The city owns and operates the water and wastewater systems providing service connections to about 183,000 customers in the city limits and outlying areas. The city's wastewater sys tern consists of 2,300 miles of pipelines, 109 wastewater lift stations, three major wastewater treatment plants, and one central biosolids processing plant. The city has experienced rapid growth over the last 20 years because of its unique blend of advanced technology and government jobs as well as its international reputation for live music and outdoor recreation. The Walt Street Journal, Forbes magazine and others have consistently ranked it among the top four American cities for livability. This media attention caused explosive population and business growth, leading to problems with the wastewater collection system and increasing numbers of SSOs.
In 1998, a lightning-induced failure of a wastewater lift station just north of Austin resulted in a discharge of raw sewage into Brushy Creek. The episode drew attention to wastewater overflows and resulted in the EPA issuing an Administrative Order (AO) requiring the city to "eliminate sanitary sewer overflows" from its wastewater collection system by Dec. 31, 2007. The AO also contains interim deadlines for completion of several tasks for different areas of the city, Figure 1. It also required a city-wide Infiltration/Inflow (I/I) study, followed by Sewer System Evaluation Surveys (SSES) for identified problem sewer sub-basins.
[FIGURE 1 OMITTED]
In order to meet the requirements of the AO, the city established the Austin Clean Water Program (ACWP). After the city conducted a professional services selection process attracting some of the largest program management firms in the country, Earth Tech Inc. was selected as program manager. The program consists of city staff working with the consulting program management team, analyzing the wastewater collection system, identifying the necessary repairs and overseeing a program of repairs and upgrades. The ACWP has been described as a model approach to solving wastewater collection system problems. It represents one of the most important environmental efforts in the history of the City of Austin Water Utility.
In order to effectively meet the conditions of the AO and to eliminate SSOs to the greatest extent possible, the city adapted a unique approach recognizing the need to perform more intensive preventive maintenance of the system. An examination of the strategy demonstrates an emphasis on cleaning, television inspection and grease and root control--important maintenance activities that will make the program effective in eliminating SSOs.
A diagram describing the specific strategic initiatives is shown in Figure 2.
[FIGURE 2 OMITTED]
Several of the most important elements of the program are the Enhanced Maintenance Program, the SSES Capital Improvements Program, the Private Property Repairs and the Policy Review Committee.
Enhanced Maintenance Program
Many of the SSOs in the city's system are of the dry weather type. To address this particular type of SSO, the city created an Enhanced Maintenance Program. This activity is targeted to address the dry weather SSOs in the non-SSES sub-basins, through much heavier cleaning of the sewers and root removal.
The process works as follows: The non-SSES sub-basins were prioritized based on their position in the AO schedule (Crosstown Interceptor Basin first, Onion Creek Interceptor Basin second, as well as by the number of documented SSOs within the sub-basins. In other words, the first basin treated by enhanced maintenance was a non-SSES sub-basin in the Crosstown Interceptor Basin, which has the most documented SSOs.
The first step in the enhanced maintenance procedure would be to "assess" the sewers in the sub-basin, for the purpose of strategically targeting the cleaning, TV inspection, root removal and minor rehabilitation activities. This would include charting the location of documented SSOs in the collection system, with art emphasis on those areas with repeat or clustered SSOs. in addition, the collection system would be physically examined. This examination would be accomplished by opening manholes and assessing solids deposition at the bottom and by inserting pole cameras to inspect the sewers immediately upstream and downstream. Based on this assessment, segments of the system would be targeted for cleaning and CCTV, root removal and minor repairs.
Repeat problem areas will be placed on a special maintenance list for extra cleaning and subsequent root removal. Service contracts are in the process of being established with private contractors to support this activity. The city's fleet of equipment for preventive (nonemergency) maintenance consists of six flushers, two vactors, and six TV trucks. In addition, two smoke testing crews and three flow monitoring crews perform investigations. The city's fleet is extensively utilized to inspect the pipelines in the Edwards Aquifer Recharge Zone to meet the State requirement of a five-year inspection cycle, to inspect the new pipelines for acceptance and warranty, and to investigate the SSOs. The city added an additional two crews to perform manhole inspections. Because all of the sewer cleaning equipment and CCTV equipment is fully utilized, the city is developing private sector service contracts for specific enhanced maintenance activities, including cleaning and CCTV, cured-in-place lining, small repairs service, manhole rehab and root removal.
The activities undertaken and the experiences derived will be incorporated into the city's Capacity Management Operation and Maintenance (CMOM) program.
SSES driven capital improvement program
The SSES capital improvements program is derived from the SSES reports prepared by consulting engineers hired directly by the city. Each SSES document contains four volumes, including all the appendices. Each report included a hydraulic model to identify capacity constraints in the system.
A typical SSES report contains a project area description, results of field investigations, an hydraulic model, recommendations and cost estimates.
The utility requested that the program management team perform an in-depth review of each SSES report to verify consistency and accuracy of the recommendations. From this review, a technical memorandum was developed that summarized the required improvements with updated cost estimates.
The capital improvements program will consist of more than 100 individual projects. These projects range in complexity from major interceptor tunnels, replacement sewers to conventional sewer rehabilitation. Rehabilitation techniques include cured-in-place liners, pipe bursting and service lateral rehabilitation. The following is a list of the initial projects with an approximate bid date, Figure 3. Many more projects will follow.
[FIGURE 3 OMITTED]
During the course of this program, it is expected that numerous system defects will be identified along private sewer laterals. These are defects that allow the introduction of infiltration and inflow into the sanitary sewer system, and contribute to the problem of SSOs, Figure 4.
[FIGURE 4 OMITTED]
It is the responsibility of property owners to install and maintain sewer lateral lines on their own property. During the SSES process, it is likely that private sewer lateral defects will be identified and classified as a "priority 1" repair. The city is reexamining its current process for accomplishing these private property repairs to see if a more effective approach is available.
One idea that the Austin Water Utility is considering is a private lateral financing program. Under this scenario the city would contract with a private lending institution to make small loans to homeowners to fund the lateral repair or replacement. It would contribute money to the Finance program in the form of interest rate buy downs, resulting in nearly interest-free financing to the homeowner. Further, the city is expected to develop a new private lateral ordinance to encourage prompt repairs to defective laterals. The city has enlisted the assistance of a task force from its ACWP Citizens Advisory Group to develop the private lateral financing program and to update the ordinance.
Policy review committee
Another interesting feature of the Austin Clean Water Program is their willingness to draw on the experience of other cities who have initially ran afoul of the EPA, but who have successfully extricated themselves and solved their own enforcement situations with EPA. The city requested that representatives of governmental entities outside Austin form a policy review committee to review key elements of the Austin Clean Water Program on an annual basis and provide constructive criticism. The committee, comprised of Luis Aguiar-Miami Dade Water and Sewer Department, Roy Herwig, EPA Region 4 (retired), Andy Cronberg, city of Fort Worth and Tony Almeida, Dallas Water Utilities (retired), brings important "lessons learned" from other major wastewater programs.
The City of Austin Water Utility has established a very progressive and organized approach to solving the problem of SSOs in the context of complying with the EPA-issued AO. The program, now entering its third year, is ahead of schedule and under budget. The city's response to the AO has become a positive experience, providing city officials with a valuable and proactive tool to enhance and maintain the collection system efficiently. Elected officials applaud the effort.
Will Wynn, the Mayor of Austin, has been duly impressed with the progress. "Our city staff has shown great leadership in undertaking the Austin Clean Water Program. Their 'never say die' attitude, cost consciousness and ability to form great partnerships with EPA, private sector contractors and the community has raised the bar on effective program management."
In the words of Council Member Brewster McCracken, "This will go down as one of the most important environmental projects that the city has undertaken in our generation. It's under budget and ahead of schedule and I'm an enthusiastic supporter of it."
Editor's Note: For more information on how to participate in this program, call William B Moriarty P.E. at (512) 479-1609 or e-mail at firstname.lastname@example.org.
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|Title Annotation:||Rehabilitation Technology|
|Author:||Cantu, Reynaldo; Guthikonda, Gopal; Moriarty, William B.|
|Date:||Apr 1, 2004|
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