By Indianapolis Mayor Gregory A. Ballard
April 11, 2011

Indianapolis is receiving national recognition for our combined sewer overflow strategies, and I am proud to share with you the story of how we achieved $740 million in taxpayer savings by renegotiating our agreement with the U.S. Environmental Protection Agency (USEPA).

Indianapolis, with nearly 800,000 residents, was experiencing wet weather-induced combined sewer overflows (CSOs) of about 7.8 billion gallons a year in the early part of the past decade. The CSOs carry a combination of rainwater, snowmelt, and domestic sewage from homes, as well as from industrial and commercial wastewater customers. City officials and professional staff were eager to reduce the overflows to protect public health, property and the urban environment. State regulators with the Indiana Department of Environmental Management (IDEM) were concerned about the wet weather combined sewer overflows, and they are compelled to require improvements to the system by virtue of the National CSO Control Policy adopted by the USEPA. The state regulating authority along with USEPA Region 5 officials entered into negotiations with Indianapolis to address the situation. The negotiations resulted in a 2006 federal court-approved Consent Decree that included a plan to dramatically reduce combined sewer overflows. Since 2008, my administration has emphasized sustainability, affordability and quality of life for the citizens of Indianapolis, and I challenged my staff to identify cost savings while complying with the Consent Decree. Another goal I charged my team with was to make our plan more environmentally friendly. Fortunately, we were able to engage in new discussions with the regulators regarding the 2006 Consent Decree and are now on a path to achieve a better environmental solution at a lower cost while developing a system with more reliable performance.

The 2006 Consent Decree required the city to implement a long-term control plan to reduce CSO overflows and achieve compliance with agreed-upon water quality standards. Some of the major elements of the original plan included the construction of 31 control measures, one of which was a shallow interceptor tunnel that could convey up to 150 million gallons per day. The net result of the ultimate plan, when completed, would reduce the 7.8 billion gallons of annual CSO overflows to 642 million gallons per year. The plan, when fully implemented, would allow the city to comply with state and federal regulations. The improvements were estimated to cost $1.73 billion (2004 dollars) over a 20-year period.

The city reexamined the approved long-term control plan in 2008 and undertook additional engineering studies to propose redesigns that would improve efficiencies and provide greater flexibility to enhance the system's performance while greatly reducing the cost to achieve compliance with the Consent Decree performance metrics. The one project redesign that provided the greatest positive impact was elimination of the shallow interceptor tunnel in favor of a 54-million gallon, 6.5-mile-long Deep Rock Tunnel Connector. The city proposed this change as an improvement, and it was approved in 2009 as Amendment 1 to the original 2006 Consent Decree.

Like most large urban centers, Indianapolis has its share of infrastructure challenges. With respect to the wastewater CSO infrastructure, we were convinced that environmentally sustainable solutions would be first in our thought process rather than an afterthought. Our Capital Improvement Plan (CIP) for the wastewater utility included a septic tank elimination program, rehabilitation of the above and below ground infrastructure, and needed system expansions. These improvements were valued at about $1.8 billion in 2006. Although they are treated as separate costs in addition to the CSO Consent Decree costs, they are intertwined in the city's overall financial capability and system performance requirements, including compliance with the CSO long-term control plan. The engineering challenge before us was how to design the system improvements to improve performance, extend the useful life of the infrastructure, enhance the efforts to reduce overflows and do it all with cost efficiencies. Additionally, our review of the total wastewater CIP in 2008 indicated that the program costs had grown by $300 million. Thus, the CSO plan originally estimated at $1.7 billion and the system improvements estimate of $1.8 billion had escalated to $3.8 billion. Based on the overall cost of the program, sewer rates to our citizens would rise to more than $100 a month.

Another challenge was to identify sustainable solutions. Emphasis was placed on less costly green infrastructure approaches incorporated with the bricks and mortar grey infrastructure solutions. A “Value Engineering” analysis identified a better and more cost-effective design with sustainable components. While sustainable concepts are typically thought of for green infrastructure, the analysis also identified significant opportunities to make the grey infrastructure components of the Consent Decree more sustainable. Pumping and treatment facilities, with high electrical and chemical consumption, were reconsidered, downsized, and/or eliminated due to storage capacities of additional tunnels that were added. This dramatically reduced the carbon footprints that would otherwise have occurred. Existing facilities were identified for rehabilitation, expansion, and/or modification, in lieu of replacement – again, saving needed resources.

In addition to the grey infrastructure deep tunnel storage for addressing combined sewer overflows, we included a system of green roofs, rain gardens and bioswales to redirect stormwater and increase urban permeability to reduce flows into the combined system. Next, the city invested $6 million in additional hydraulic modeling and investigation of our watersheds, which gave us better engineering information and allowed us to refine the designs of our proposed tunnel and treatment facilities. We found that wet weather flows were 30 percent less than originally anticipated.

Because of these factors and the flexibility of the language in our Consent Decree, the city proposed a second amendment to the amended Consent Decree that included these new concepts that still satisfied compliance with our combined sewer overflow water quality performance requirements. The net result, from the city's perspective, is a more sustainable solution that reduces the overall infrastructure investment by $740 million (measured in 2004 dollars), and achieves an additional reduction of overflow volume of 30 million gallons per year compared to original Consent Decree. On November 8, 2010, the USEPA and U.S. Department of Justice announced their approval of the amended plan, stating in their press release that the Amendment will “Reduce Pollution at Lower Costs” and that they perceived it as a “win-win” for both the environment and the city.

While the Indianapolis Consent Decree negotiations were not among the first such CSO enforcement actions, it was completed early in the city's overall wastewater system planning process. The 2006 Consent Decree was based on preliminary information from the perspective of flow monitoring, modeling and watershed characterization. This led to the formulation of engineering plans that made assumptions that were not as well-refined. The studies and the flexibility in our Consent Decree provided critical information prompting us to petition to reopen the Consent Decree, and the new information justified the reengineering of the long-term control plan. In hindsight, we should have urged the parties to gather more and better physical information, even if it took more time.

Another important lesson learned is that due to the exceedingly high cost of compliance with the National CSO Control Policy, cities should consider overall system improvements that incorporate an appropriate mix of grey and green infrastructure in the long-term control plan. We found that future grey infrastructure can be made more sustainable without fully converting to green infrastructure. The “right mix” of green and grey infrastructure should, in each case, be determined through engineering analyses rather than experimentation or wishful thinking. We also found, as a result of commissioning value engineering analyses, that costly system rehabilitation and expansion decisions should be considered – and blended in if possible – simultaneously with the development of CSO compliance plans. We found that the synergies between the two efforts resulted in better environmental outcomes at reduced costs.

Finally, cities should view CSO Consent Decrees and the resulting long-term control plans as works in progress rather than as fixed final solutions. Any city that wants to reopen a CSO Consent Decree should have the proper engineering evaluations to rely on to convince a federal court, the USEPA and its state regulatory authority of the merit of proposing an amendment to the long-term control plan. We found that changes in our engineering strategies were accepted when an improved environmental solution is solidly based on a fact-based case.

The winners in our case are the people of Indianapolis, the commercial and industrial community that relies on the wastewater system, and the environment. Sustainable CSO solutions are in everyone's best interest.