Terre Haute Cleanwater


Long Term Control Plan

LTCP Development and Results Summary

In an average year, a continuous simulation of the sanitary sewer collection system model for the City of Terre Haute predicts that 284 million gallons of combined sewage is discharged from CSOs. Terre Haute is fortunate in that the receiving stream has a large average flow rate relative to the volume of CSO overflow, which can provide significant assimilative capacity or dilution. Despite this fact, simulations indicate that in an average year, the Wabash River exceeds the water quality standards for E. coli approximately 30% of the time during the recreation season (April-October) when bacteria loads from all pollutant sources are considered and less than 5% of the time if non-CSO sources effects are eliminated.

Flow, water quality and rainfall data were collected and both the combined sewer system and the Wabash River in the CSO areas were modeled to assist in the City's CSO LTCP planning process. No areas were qualified as “sensitive areas” but the outfalls around Fairbanks Park were designated as a priority. The LTCP recommended a plan to reduce the number of CSO events per year (average year) from 37 to 6 times per year, which will reduce the number of hours when bacteria loadings from the CSO’s exceed recommended levels in the river by 75%, from 174 hours to 45 hours.

Both Federal and State CSO policies are divided into two phases. Phase I (CSO Operational Plan) was submitted to IDEM and approved by IDEM in 1996 with the most recent update in 2006. Phase II includes the LTCP and the submittal of the document completed in 2011. All of the regulatory requirements are intended to reduce the in-stream impact from CSO discharges during wet conditions and ultimately make the Wabash River more compliant with its official classification of “fishable and swimmable”.


Project Approach

The final revised project approach used to evaluate CSO long-term control alternatives was as follows:

  • Identify feasible CSO control technologies.
  • Based on new collection system flow and rainfall data monitoring collected in 2006 - 2008, calibrate and develop a SWMM model for evaluation of CSO system reaction to storm events and control alternatives
  • Develop integrated system-wide CSO control alternatives to capture and treat typical year rainfall at various levels of control (measured in number of overflows per year). Each alternative included feasible CSO control technologies specific to each CSO or combinations of CSOs, and other technologies identified by the City and the Citizen Advisory Committee (CAC) that would reduce CSO impacts on the Wabash River.
  • Estimate the cost for each feasible CSO system alternative and also for complete combined sewer separation.
  • Evaluate each CSO alternative’s performance using a “typical year” rainfall approach and calculate the associated costs for various levels of control.
  • Perform an economic affordability evaluation and determine if a Use Attainability Analysis (UAA) must be performed if the design storm flow requirements as prescribed by IDEM cannot be economically achieved.
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The City of Terre Haute's Final Long Term Control Plan was submitted to IDEM in January 2011 and approved inAugust, 2011. The LTCP Documents are available for download and review.

CSO LTCP Team

The Terre Haute CSO LTCP team consisted of several groups including consultants, members of the City's utility and engineering staff and appointed advisors.

The primary project engineering consultant was HWC Engineering. The river modeling work was completed by Limno-Tech, Incorporated of Ann Arbor, Michigan, and the financial capabilities analysis and user rate work was performed by H.J. Umbaugh & Associates. Fred Andes of Barnes and Thornburg served as special legal counsel and advisor to the team.

The technical review team consisted of members of the City Wastewater Treatment Plant Staff, the City Engineering Staff and the Consultants.

As required by IDEM, a Citizens Advisory Committee was appointed by Mayor Duke Bennett. This group met five times during the CSO LTCP process and provided public review during the development of a recommended plan.

The team also included the City government groups (City Council, Board of Works and Sanitary District) that approved the recommended plan or will be responsible for adopting measures necessary for LTCP implementation.

Long Term Control Plan Goals

As the CSO LTCP process evolved, goals varied and were subsequently modified. The following general goals were originally established for the City of Terre Haute at the onset of the original plan:

  • Meet the IDEM requirements of the LTCP guidance and Senate Bill 431 and CSO related NPDES permit requirements.
  • Develop and select an alternative that meets the “first flush” capture criteria and the knee of the curve.
  • Add in options that eliminate overflows in the priority areas by re-routing the overflows downstream of the park.
  • Upgrade combined sewer overflow related transport and treatment facilities that are in significant need of upgrade regardless of which alternative and/or option is selected.
  • Select a plan that can be implemented in phases over a reasonable period of time.
  • Minimize the impact of implementing the selected plan on the sewer rates for the Terre Haute citizens, commercial and industrial community.

After the initial review of the plan by IDEM and the updated plan requirements for design storms were implemented, the following goals supplemented the original goals:

  • Meet the IDEM requirements of the LTCP guidance, Senate Bill 431, updated IDEM policy requirements and CSO related NPDES permit requirements and revise the plan as required by IDEM’S review and/or comments of the initial plan
  • Explore additional options that eliminate overflows in the priority areas at the first flush design event by selecting alternatives which address effects of overflows on these areas.
  • Select a plan that can be implemented in phases over a reasonable period of time.
  • Minimize the impact of implementing the selected plan on the sewer rates for the Terre Haute community taking into account CSO control and other utility needs.

Project Work Plan

Based on the project goals, the original project work plan consisted of the following activities, shown in their order of sequence:

  • Collect data on the physical characteristics of the CSO system, Wabash River and the Wastewater Treatment Plant (WWTP).
  • Capture water quality and quantity data by use of flow meters, rain gauges and a field sampling/testing data.
  • Develop a range of design storms based upon historical storm events.
  • Model the CSO system and WWTP performance at the various design storm events and calibrate the model based on actual field data.
  • Using the calibrated sewer system model, develop anticipated overflow volumes and durations for the design storm events.
  • Develop alternatives (three minimum) that utilize acceptable technologies to capture and treat combined sewer overflows to a design storm.
  • Develop options to supplement the CSO control alternatives that re-locate the overflows of two, three or all four of the active CSO’s in the Fairbanks Park area to a point downstream of this priority area.
  • Develop and calibrate the river model to estimate the reduction in water quality impacts that will occur as a result of implementing CSO improvements at the various design storms.
  • Develop a capital cost and operation, maintenance and replacement (O, M & R) costs for the alternatives at the various design storms.
  • Utilizing the river model data and cost estimates develop a curve that indicates water quality improvements as they relate to capital and O, M & R cost improvements. Select the “knee” of this curve (the point in which a significant gap between increasing CSO control and water quality improvement appears) and determine if this point meets the IDEM CSO volume reduction guidelines.
  • Determine if the total estimated project costs and O,M & R costs on a Present Worth Basis at the knee of the curve exceed or fall below the 2% equivalent affordable cost based on median household income described in IDEM’s guidance.
  • Determine the reasonable CSO project implementation timeline based upon the estimated City financial capability index, IDEM standards and project team input.
  • Develop a schedule that divides the recommended improvements into phases over the implementation timeline.
  • Determine anticipated sewer rate increases for the typical homeowner in Terre Haute utilizing various financing options. As with the phasing of the Capital Cost Improvements and O, M & R increases, develop a plan to phase in the needed sewer rate increases over the implementation period.

The original work plan was implemented over an 11-month period while the study was being completed in 2001 and 2002. Numerous meetings, conference calls, updating reports and draft review documents were developed and distributed among this Technical Review Group, Citizens Advisory Committee and City Government Groups by the Consultant Team throughout the process. All key decisions involved input from all parties of the team.

Over the past several years (primarily after 2006), the City of Terre Haute has completed additional research and modeling in order to revise and improve the original CSO LTCP. Additional system characterization data has been collected, hydraulic and water quality models were enhanced, a detailed evaluation of the initial alternatives was conducted resulting in the formulation of new alternatives for consideration, and consideration was given to changes in Indiana Water Quality Standards. After the initial review by IDEM and impementation of new regulations, the work plan was modified to include the following:

  • By means of new flow monitoring and a Storm Water Management Model (SWMM), develop anticipated overflow volumes and durations for the design storm events (required by IDEM) and calibrate the SWMM model based upon real time monitored data
  • Conduct SWMM Model and River Model evaluation of screened alternatives at various levels of control
  • Develop alternatives that utilize acceptable technologies to capture and eventually treat the typical year storm volumes.
  • Develop capital and annual operating, maintenance, and replacement costs for the alternatives at the typical year rainfall.
  • Determine if the total estimated project costs exceed the affordability limits.
  • Determine, based on affordability, whether a Use Attainability Analysis (UAA) will be necessary to change the classification of the river during and immediately after CSO events, and if so, complete the UAA after LTCP implementation.
  • Determine the reasonable CSO project implementation timeline based upon the calculated City financial capability index, IDEM standards and project team input.

Evaluation of Alternatives

Alternatives Considered, Screened & Evaluated

A variety of CSO capture alternatives were
considered in the LTCP including:

Storage 

Conveyance 

High Rate Treatment 

System-wide Separation 

Storm water flow reduction 

These technologies were screened and then
evaluated with consideration for:

 Initial costs

 Annual O&M costs

 Local affordability

 Ease of implementation

 Environmental impacts


Two factors significantly impacted the consideration of four final alternatives that were evaluated in greater detail. The first factor was the purchase of the former International Paper site along the river by the City of Terre Haute and which includes several large earthen ponds located adjacent to the City’s main combined sewer pumping station in 2010. The second factor was the City’s decision to significantly increase the peak, sustained wet weather treatment capacity at the WWTF to 48 MGD. These two developments were used in consideration of the final alternatives set aside for detailed evaluation.

One final alternative evaluated was a CSO tunnel (approximately 40 feet deep) connecting all of the CSO outfalls to a new main lift station and utilization of the IP site (approximately 30 MG) for storage. The other final alternatives all included construction of a large diameter open cut gravity interceptor from Fairbanks Park (consolidating and closing all of the outfalls within the park) and using the IP site for storage of CSO flows or high rate treatment. Each of the alternatives (excluding the tunnel) included consolidation of the northern two CSO outfalls and storage near CSO 010. A new main lift station to replace the City’s existing aging lift station (which would eliminate outfall 002) was considered in three of the final alternatives as well as the use of green infrastructure within the basins 009 and 010 to capture flow before entering the combined system.

The four final screened comprehensive alternatives are as follows:

Alternative #1  -   7B

  • Tunnel Storage
    • Build a new 16 foot diameter tunnel below 1st Street/SR 63
      • Begins at the northernmost CSO outfall (CSO 010) and ends at the southernmost CSO outfall (CSO 002)
      • New diversion structures at each CSO outfall direct flows that exceed the existing main interceptor sewer capacity to the new tunnel
      • Tunnel could store over 20 million gallons of combined sewage
  • Lagoon Storage
    • Use one of the existing lagoons at the former International Paper site to store an additional 27 million gallons of combined sewage
    • When peak flows subside, the stored sewage will be pumped to the wastewater treatment facility by the new Main Lift Station
  • Main Lift Station
    • Build a new Main Lift Station at the former International Paper site
      • New Main Lift Station will serve to empty both the tunnel and the lagoon storage areas, as well as the existing main interceptor, by pumping waste to the City’s wastewater treatment facility
  • CSO Outfalls that will remain OPEN:
    • #003, #009, #010, #011
  • CSO Outfalls that will be CLOSED:
    • #002, #004, #005, #006, #007, #008,

Alternative #2  -   11

  • Relief Sewer
    • Build a new 12 foot diameter relief sewer along the Wabash River
      • Begins at the US 40 Bridge (CSO 008) and ends at the southernmost CSO outfall (CSO 002)
      • New relief sewer will be built alongside the existing main interceptor sewer that will remain in service
      • New diversion structures at each CSO outfall direct flows that exceed the existing main interceptor sewer capacity to the new relief sewer
  • Lagoon Storage
    • Use one of the existing lagoons at the former International Paper site to store about 27 million gallons of combined sewage.
    • When peak flows subside, the stored sewage will be pumped to the wastewater treatment facility by the new Main Lift Station.
  • Main Lift Station
    • Build a new Main Lift Station at the former International Paper site
      • New Main Lift Station will serve to empty the lagoon storage areas and pump flows from the relief sewer and main interceptor sewer to the City’s wastewater treatment facility
  • North Relief Sewer and Storage (at Chestnut Street)
    • Build a new relief sewer between CSO 009 and CSO 010 to transport flows from 009 to 010 so that CSO 009 can be closed
    • Based on effectiveness of green infrastructure in basins 003, 009 and 010, potentially build a new concrete storage tank below ground to store 2.0 million gallons of combined sewage at CSO 010
    • Build a new lift station to transport flows from the new storage tank back into the existing main interceptor sewer so they can be treated at the wastewater treatment plant
  • CSO Outfalls that will remain OPEN:
    • #010, #011
  • CSO Outfalls that will be CLOSED:
    • #002, #003, #004, #005, #006, #007, #008, #009

Alternative #3  -   Hybrid

  • Relief Sewer
    • Build a new 6 foot diameter relief sewer along the Wabash River
      • Begins at the US 40 Bridge (CSO 008) and ends at the southernmost CSO outfall (CSO 002)
      • New relief sewer will be built alongside the existing main interceptor sewer that will remain in service
      • New diversion structures at each CSO outfall direct flows that exceed the existing main interceptor sewer capacity to the new relief sewer
  • Lagoon Storage
    • Use one of the existing lagoons at the former International Paper site to store about 27 million gallons of combined sewage.
    • When peak flows subside, the stored sewage will be pumped to the wastewater treatment facility.
  • CSO Pump Station
    • Build a new CSO Pump Station at the former International Paper site.
      • New CSO Pump Station will serve to empty the lagoon storage areas and pump them back into the main interceptor sewer for treatment at the wastewater treatment facility
  • North Storage (at Chestnut Street)
    • Build a new concrete storage tank below ground to store 1.0 million gallons of combined sewage at CSO 010
    • When peak flows subside, the stored sewage drains back into the existing system for treatment
  • Central Storage (at Hulman Street)
    • Build a new concrete storage tank below ground to store 8.1 million gallons of combined sewage at CSO 004
    • When peak flows subside, the stored sewage drains back into the existing system for treatment
  • CSO Outfalls that will remain OPEN:
    • #002, #003, #009, #010, #011
  • CSO Outfalls that will be CLOSED:
    • #004, #005, #006, #007, #008

Alternative #4  -   11B

  • Relief Sewer
    • Build a new 12 foot diameter relief sewer along the Wabash River
      • Begins at the US 40 Bridge (CSO 008) and ends at the southernmost CSO outfall (CSO 002)
      • New relief sewer will be built alongside the existing main interceptor sewer that will remain in service
      • New diversion structures at each CSO outfall direct flows that exceed the existing main interceptor sewer capacity to the new relief sewer
  • Main Lift Station
    • Build a new Main Lift Station at the former International Paper site
      • New Main Lift Station will serve to empty the lagoon storage areas and pump flows from the relief sewer and main interceptor sewer to the City’s wastewater treatment facility
  • High Rate Treatment
    • Build high rate clarification and ultraviolet disinfection facility at the former International Paper site to provide primary treatment for overflows from new Main Lift Station
    • The new high rate treatment facility will have capacity to treat 32.5 million gallons per day
    • When flow at the new Main Lift Station exceeds its capacity, it will overflow to the new high rate treatment facility before being transported to the Wabash River
  • North Relief Sewer and Storage (at Chestnut Street)
    • Build a new relief sewer between CSO 009 and CSO 010 to transport flows from 009 to 010 so that CSO 009 can be closed
    • Build a new concrete storage tank below ground to store 2.0 million gallons of combined sewage at CSO 010
    • Build a new lift station to transport flows from the new storage tank back into the existing main interceptor sewer so they can be treated at the wastewater treatment plant
  • CSO Outfalls that will remain OPEN:
    • #003, #010, #011
  • CSO Outfalls that will be CLOSED:
    • #002, #004, #005, #006, #007, #008, #009

Public Participation

Public Participation is an IDEM requirement for completing all LTCP processes. The public was involved in many ways during the Terre Haute plan development including both City government officials and private citizens. Several City government divisions including the City Council, the Board of Public Works and Safety, the Terre Haute Sanitary District Board of Commissioners and the Terre Haute Wastewater Treatment Plant were brought into the LTCP development process.

Perhaps the most important public participation came from the Citizen’s Advisory Committee (CAC) which included a diverse group of stakeholders from the community. A series of meetings were held with the CAC over a 10 year period to explain the process of determining alternatives for control and to garner input throughout the project.

Public Education was handled through various means. The CAC helped to educate the public at its meetings and through various meetings its members attended. A brochure outlining Terre Haute’s plans was distributed and several newspaper articles were published in the local newspaper. Warning signs were installed at all of the outfall structures to provide information about potential health risks associated with structure overflows. A website was created early in the process to educate the public on the issues that CSOs cause and what the City is doing to rectify the problems associated with them.



Funding and Implementation Schedule

Funding of a LTCP is perhaps the greatest challenge in developing the plan. The goal in funding is to determine the level of CSO control or reduction that the community can provide without causing undue hardship on the City or on the individual households within the community. The guidelines provided by the EPA and IDEM consider the ability to contribute financially of both residents, and the City, to help determine the affordability of a plan's cost and the schedule implementation length for the plan. The recommended plan is not the most or least expensive of the four final alternatives considered for implementation but it achieves an acceptable balance between CSO control and financial burden.



Recommended Plan

After reviewing the environmental performance, cost-effectiveness and affordability, operability, reliability, and constructability, a recommended plan was developed that reduces CSO volume discharging to the river by 72%, results in 96% capture of wet weather flow, eliminates all CSOs in Fairbanks Park and results in no more than six overflows in a typical year at the remaining CSOs. The recommended plan will utilize a combination of greater wet weather treatment capacity at the City’s wastewater treatment facility, a 33 MGD high rate treatment facility at the former International Paper (IP) Brownfield site, a new main pump station to replace the existing facility constructed in 1965, a new large diameter CSO gravity sewer interceptor along the Wabash River between Fairbanks Park and the new main lift station and either “gray” or “green” CSO storage facilities at the north end of the CSO system. Provisions for in-line storage of CSO flows and capture of floatables material from overflows remaining active were also part of the plan. Eight of the ten existing CSO outfalls will be closed off completely. The estimated cost of the recommended plan is $125 million and the recommended implementation schedule for the plan is 20 years.




  • Every year millions of gallons of combined sewage, stormwater, and debris overflow to the Wabash River.
  • The overflows cause increased E. coli readings and other pollution to the river.
  • The City of Terre Haute is undertaking a program to reduce the number of overflows to the river.
  • The goal of the CSO Reduction Program is to have a cleaner city, resulting in a cleaner river.
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