Combined Sewer Overflow (CSO) Control Program- Summer 2010

The City of Newport has over 90 miles of sanitary sewer pipes, many of which have been in operation for over 100 years. Prior to the 1970's, many of these pipes were designed as combined sewers- collecting both sanitary sewage as well as storm water during wet weather events.

Since the 1970's, the City has constructed several projects to separate the storm water connections from the sanitary sewer to reduce the number of CSO Events.

In November 1997 the Rhode Island Department of Environmental Management (RIDEM) issued the final discharge permit to the City including time schedules associated with study work at the Washington Street and Wellington Avenue Combined Sewer Overflow (CSO) Facilities.

In November, 1999 the City entered into a consent agreement (RIA-292) with the RIDEM regarding a plan to address the City's CSO Control Program. As required by the consent agreement the City submitted three Technical Memorandums (TM) that would be used to develop a detailed scope of work to develop a CSO Control Program in compliance with RIDEM and USEPA CSO Policies.

Between 2000 and 2004 the RIDEM and City discussed the approach for the CSO Control Program. In July 2004 the RIDEM approved the Request for Proposals prepared by the City for engineering services associated with the development of the City's CSO Control Program. The CSO long term control plan will be developed as a phased approach.

After RIDEM approval, the City Council awarded the contract to EarthTech in November, 2004. The program would initially address the Wellington Avenue CSO Facility as it was prioritized due to the USEPA designation of King Park Beach as a Flagship Beach.

Phase 1

The Phase 1 Part 1 work consisted of the following tasks and the work was completed in October, 2005:

     Data Collection/Field Investigations
  • Flow Metering of service area to Wellington Ave CSO Facility
  • Identification and Prioritization of Catchment Areas
  • Thames Street Interceptor Manhole Inspections
  • Identified Work for Phase 1 Part 2

The work completed in Phase 1 Part 1 was submitted was submitted for review and approval by the RIDEM to proceed with the work associated with Phase 1 Part 2. Approval was received and EarthTech was authorized to proceed in February, 2006 with the following tasks:

  • Thames Street Interceptor TV Inspection
  • Flow metering in Catchment Area 6
  • Hydraulic Model Evaluation
  • Windshield Surveys
  • The following field work in the prioritized Catchment Areas 1, 3, & 4
    • Flow Isolation/ Follow up CCTV
    • Manhole Inspections
    • House to House Surveys
    • Smoke Testing
    • Dye Testing
  • Report on Results and Recommendations due to RIDEM January 31, 2007

The Phase 1 Part 2 report which contains recommendations for Phase 2 work was reviewed and approved by the RIDEM in May, 2007. The City authorized EarthTech to proceed with the Phase 2 work in July, 2007.

Phase 2 uses the field work from Phase 1 to identify long term improvements to the sewer system in order to comply with the RIDEM and EPA CSO policies. The primary goal is to eliminate overflows from the Wellington Avenue facility. The Phase 2 results and recommendation are due to be submitted to RIDEM for review and approval by February 28, 2009.

The Phase 1 Part 2 report also identified work that the City could proceed with prior to final approval of the report. A Phase 1 Part 3 contract was awarded to EarthTech in November 2006 and included the following tasks:

  • Design for disconnection of 28 catch basins and rehabilitation of 290 manholes
  • Smoke Testing for Area 6
  • House to House surveys -Area 6
  • Flow isolation -Area 6
  • Dye testing - Area 6

Subsequently, the City awarded construction contracts to disconnect the catchbasins in July 2007 and repair manholes in September 2008. The repair work has been successfully completed.

Phase 2

The City authorized AECOM (formerly EarthTech) to proceed with the tasks for Phase 2 in August 2007. Phase 2 uses the field work from Phase 1 to identify long term improvements to the sewer system in order to comply with the RIDEM and EPA CSO policies.

The primary goal is to eliminate overflows from the Wellington Avenue facility. The Phase 2 report with results and recommendations was submitted to RIDEM for review and approval on March 31, 2009.

The report recommended a CSO control plan for the Wellington Avenue facility including obtaining additional sewer separation in combination with storage.

In addition work was recommended in the Washington Street CSO facility service area similar to the work completed in Phase 1 for the Wellington Avenue service area. The report concluded that improvements within the Wellington Avenue service area alone can not achieve compliance at the Washington Street CSO facility.

The tasks in Phase 2 included the following:

  • Develop a calibrated hydraulic computer model of the collection system
  • Use the model to analyze existing and proposed conditions in the Wellington Ave facility service area
  • For proposed CSO control alternatives determine the impact of the control alternatives on the Washington St . CSO facility; Long Wharf pump station; and the Water Pollution Control Plant
  • Identify and recommend a long term plan for Wellington Ave. facility (i.e. sewer separation, storage and conveyance, etc.)
  • Design and prepare construction documents for the high priority sewer defects identified in Phase
EPA Intervention

In March, 2009, EPA notified the City of its intent to intervene in the consent agreement negotiations between the City and the RIDEM. In September 2009, EPA issued a draft consent agreement to the City stating that all CSOs be eliminated by 2015.

The City is actively negotiating the action items and schedule for this consent agreement with the EPA and the RIDEM.

CSO Control Program Implementation

In March 2010, the City contracted with CH2M Hill to serve as Program Manager to assist the City in negotiations with the EPA and the RIDEM with the development of a Corrective Action Plan for the City's CSO Control Program which will be part of a consent agreement executed between the City, EPA and RIDEM. CH2M Hill will assist the City with the coordination and implementation of the CSO Control Program.

Recent Accomplishments

Although the draft consent agreement with the EPA has not been finalized, the City has proceeded with a number of activities from the draft Corrective Action Plan. The recently completed activities include:

  • 35 meters installed in the sewer system which will remain in place for a year to assist in identifying sources of extraneous flow into the system
  • Long Wharf Force Main emergency repair project completed
  • Wellington Avenue sewer interceptor replacement design completed
  • A report summarizing the recommendations contained in the prior extraneous flow investigations, the status of the City's implementation of each recommendation, and an updated remedial plan and implementation schedule for prior recommendations that have not been completed by the City
Upcoming Activities

In an effort to address action items from the draft Corrective Action Plan, the City is currently conducting the following activities:

  • Analyzing data collected from the 35 sewer system meters
  • Enhancing and updating the City's GIS wastewater collection system mapping
  • An optimization study of the City wastewater treatment facility located on Connell Hwy.
  • Improvements to the Rail Road sewer interceptor located in the railroad right of way between Van Zandt Ave. and Bridge St.
  • Constructing repairs to the High Priority Sewers designed by AECOM in Phase 2
  • Constructing Catch Basin separation in Area 6 as identified by AECOM in Phase 1
  • Design of improvements to the Thames Street sewer interceptor
  • Expanding the hydraulic model to the entire sewer system
Future Activities

The City has planned the following activities to occur in 20101 and 2011 in compliance with the draft Corrective Action Plan:

  • Construction of the Wellington Avenue sewer interceptor replacement
  • Construction of improvements to the Thames Street sewer interceptor
  • Conduct investigations to identify public and private sources of extraneous flow entering the sewer system throughout the City's sewer collection system
  • Complete an assessment of the current capacity of the sewer collection system
System-wide Master Plan

In addition to the activities to be completed in compliance with the draft Corrective Action Plan, the City is planning to complete a System Master Plan with estimates of the associated costs for the CSO Program in November 2012.

The purpose of the System Master Plan will be to utilize all of the data collected to date as part of the Corrective Action Plan along with an evaluation of the effectiveness of projects that have been completed in order to develop a system-wide plan to reduce CSO events in the future.

While many studies have been completed to date on the City's system, it is beneficial to step back during the implementation phase to evaluate the effectiveness of the projects and to update the plan going forward in order to achieve better results and control costs.



The City of Newport, Rhode Island | City Hall | 43 Broadway | Newport, RI 02840 | 401-845-5300