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Private Infiltration Removal Policy

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Since 2008, the Engineering Department has followed a sustained methodical approach to identify and repair leaks in our Town-owned sewer system in an ongoing effort to reduce infiltration entering our system. For those not familiar with Infiltration please visit our Infiltration & Inflow page.

In FY 2019, Dedham's sewer assessment to the Massachusetts Water Resources Authority (MWRA) was $5.6 million. The cost breakdown based on flow was as follows:

  • Cost to transport & treat Sanitary Flow = $2.9 million (52%)
  • Cost to transport & treat Infiltration = $2.1 million (37%)
  • Cost to transport & treat Inflow = $0.6 million (11%)

As we continue to inspect our Town-owned sewer system, we have identified that the problem of infiltration also exists in the private sewer connections made to the Town's system. In an effort to keep our sewer rates as low as possible (as of 2019, rates have not increased since 2008!) the Town must find a way to remove infiltration from the private sewer connections that show excessive amount of infiltration entering the system. This has spurred the need for a removal policy for these private connections.

Our discussions on a Private Infiltration Removal Policy began in February 2019, when the Engineering Dept. made a presentation to the Select Board. This presentation discussed the history of Inflow & Infiltration (I/I) and what our department has accomplished since FY2007. It also showed the results of our private sewer connection inspections performed in 2018 and the need for a policy to remove infiltration from these private sewer connections. Click here to download and view that presentation.

In March 2019, an insert was placed into every sewer customer's sewer bill. This insert provided customers with some educational material on what I/I is and how much money it costs the Town in MWRA assessments to pay for the transportation and treated of this clean water. The insert also invited all the customers to attend a Public Meeting on April 1st to learn what has been done by the Town since FY2007 to remove I/I from our Town-owned sewers and what is involved with creating a Private Infiltration Removal Policy. Click here to download and view the March sewer insert.

On April 1, 2019 the Town held an open public meeting to discuss our efforts to remove I/I from the Town-owned sewer system, the results of our private sewer connection inspections performed in 2018 and the major components that go into the creation of a Private Infiltration Removal Policy. During this presentation, we had an interactive segment where the audience members were provided with a clicker where they could select an answer to some mulitple choice questions we presented to them at this meeting. This was done to gather data on what the public feels is important in developing the policy. A copy of the public presentation and the results of the interactive segment can be downloaded below for you to view.

Based upon the feedback we collected at this meeting, the Engineering Dept. decided that a survey to collect data from more of our customers and residents were needed. Therefore in June, we created a sewer survey that was available online to all residents and customers and was also mailed in hardcopy form to all of our customers through another sewer bill insert. We have approximately 8,000 sewer customers and we received back 1,330 completed surveys. Of those completed, 773 surveys were completed online and 557 surveys were mailed in to our department. The results of the survey and the 391 comments provided in the survey can be downloaded below for you to view.

After compiling the results of the survey, we began working with Town Counsel to draft a Private Infiltration Removal Policy. A copy of the draft policy along with the results of our sewer survey were presented to the Select Board in October of 2019. Click here to download and view that presentation.

Below are our next steps and as we move closer to a final version of the Private Infiltration Removal Policy:

  • We will be conducting a Focus Group on Thursday, December 5th from 5:00 PM to 6:30 PM at the Dedham Middle School to get feedback on some of the finer details of the draft Private Infiltration Removal Policy. If you are interested in being a member of the Focus Group, please send your contact information to by Tuesday, November 26th. We will need 12 to 16 volunteers for the Focus Group. We will randomly select from those interested and contact you to confirm your availability.
  • In January of 2020 we plan to present the final version of the Private Infiltration Removal Policy to the Select Board for their consideration.








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