Improving Our Community Waterways Together

Integrated Overflow Abatement Plan Details

An Integrated Overflow Abatement Plan (IOAP) plan has been prepared by MSD in response to its Consent Decree with the USEPA and the Kentucky Environmental and Public Protection Cabinet dated August 12, 2005, and amended on April 15, 2009.

MSD's IOAP is a long term plan to control combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs) in the community. The draft IOAP has been updated and was submitted to the USEPA and the Kentucky Environmental and Public Protection Cabinet on December 19, 2008, prior to the December 31, 2008 deadline.

Since that time, MSD has been working closely with the reviewing agencies to clarify the IOAPs regulatory compliance approach, proposed level of overflow control, schedule and budget.  MSD received a conditional letter of approval from the regulatory agencies on October 23, 2009. 

As such, the revised IOAP is now available online for public review.

Driven by the values-based benefit-cost analysis, the IOAP reflects a balanced mix of green infrastructure and gray solutions to prevent and control sewer overflows.  “Green infrastructure” solutions include options such as vegetated roofs, rain gardens, rain barrels, porous pavement, and bioretention, while “gray” solutions include options such as storage, treatment, conveyance/transport, and sewer separation.  As a guiding principle, MSD’s IOAP has been developed based on front-end consideration of source control and green infrastructure.  This means that more traditional “gray” infrastructure in the IOAP has been sized after considering both (1) the anticipated flow-reduction benefits of programmatic and site-specific green infrastructure solutions and (2) the anticipated effectiveness of other source control approaches, including reduction of private sources of I/I.

Green solutions in the IOAP will be implemented during the early phases of projects, to allow data to be gathered on the flow reduction benefits that occur.  Approximately 17 percent of the Final CSO LTCP budget is allocated to green infrastructure, and most of that is planned to support projects in the first six years of IOAP implementation.  Prior to the final design of supporting gray solutions, the actual flow reduction performance will be documented and compared against the estimated targets.  The final sizing of the gray solutions will then be based on actual documented performance of green infrastructure solutions, as well as any further green and source control investments justified by performance information.  Green infrastructure investments are estimated to reduce the initial costs of CSO gray infrastructure projects by $40 million; potential future savings could double or triple this amount.

Volume 1 - Integrated Overflow Abatement Plan
This volume describes overarching, programmatic aspects that are common to all parts of the IOAP as well as the requirements, processes, and factors influencing the development of the Final CSO Long-Term Control Plan LTCP (Volume 2) and the Final Sanitary Sewer Discharge Plan (SSDP) (Volume 3).

Volume 2 - Final Long-Term Control Plan
This volume of the IOAP focuses on the control and mitigation of the CSOs.

Volume 3 - Final Sanitary Sewer Discharge Plan
This volume of the IOAP focuses upon the elimination of unauthorized discharges from both the Combined Sewer System and the Sanitary Sewer System.

Due to the overwhelming file size of all three volumes of the full IOAP including its appendices, digital copies of the documents are available on several DVDs by special request for a total cost of $35.00. Requests for DVD's must be made by contacting:

Lynn Imaging, Inc.
(502) 499-8400
Fax: (502) 499-0022

Store hours: Mon-Fri 8:00 am to 5:00 pm

Ask for "MSD 2009 IOAP DVDs". Various payment terms and delivery methods are available from Lynn Imaging.

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