Disinfection Byproducts



Stormwater - Why should we care?



THM Background Information


What are we doing to correct the problem?


We have been working to minimize the likelihood of disinfection byproducts in our water for several years.  Our efforts include optimizing our treatment processes to reduce the residual organics in the finished water and the reduction of chlorine.  These efforts have delayed violations of the regulations but have not been enough.

Upon learning that one of our THM test sites exceeded EPA standards, we notified the Massachusetts Department of Environmental Protection.  Pursuant to State and Federal Drinking Water Regulations, the Town published the following public notice in the Patriot Ledger on 10/14/2015.  



THM Public Notification

In addition, we sent the notice as well as general information about disinfection byproducts to all postal addresses in the Town of Hanover.   Finally, we have engaged the services of a consulting engineer, Weston and Sampson, to help us work towards a solution.  This solution will include short term immediate actions as well as long term operational and capital improvements.  This work has just begun, but we will begin implementation of the immediate actions soon.  We invite you to check this page often for updates as the plan evolves as well as for timely information regarding scheduling.  


Immediate Action #1 - Periodic Flushing


Disinfection byproducts form over time as chlorine in the water reacts with residual organic matter.  The areas of the water distribution system that have the oldest water are the areas that are most vulnerable to disinfection byproducts.  As such, the Town, working with our engineers, has developed a flushing plan for the north and northwest sections of Town.  The map below shows the area to be flushed.  The mains that will be flushed are highlighted in yellow on the map.

THM Flushing Map


The area to be flushed is quite large so we have broken it down into sections with specific procedures for each section.  
At the bottom of this page is a rough schedule of when we plan to flush each section.  This schedule is subject to change based on available personnel, available water, and the weather.  We will do our best to update you as changes are made.

Section I is shown below.  The streets to be flushed are highlighted in yellow.  The procedures we plan to use to flush this section are as outlined in the following attached document.  We invite you to click on the link to explore how we plan to flush this section:   THM Flushing Procedures - Section 1 (PDF)  



THM Flushing Section 1 





Section 2 is shown below.  The streets to be flushed are highlighted in yellow.   The procedures we plan to use to flush this section are as outlined in the following attached document.  We invite you to click on the link to explore how we plan to flush this section:   THM Flushing Procedures - Section 2 (PDF)  



THM Flushing Section 2



Section 3 is shown below.  
The streets to be flushed are highlighted in yellow.   The procedures we plan to use to flush this section are as outlined in the following attached document.  We invite you to click on the link to explore how we plan to flush this section:   THM Flushing Procedures - Section 3 (PDF)  



THM Flushing Section 3



Disinfection Byproduct Flushing Schedule



Disinfection Byproducts Flushing Schedule - 5-18-16


In addition to flushing, what is the plan to correct the problem?


As required  by our administrative consent order with Mass DEP, we were required to provide a letter to MassDEP prior to 8/1/2015  explaining our immediate proposed actions to manage TTHM's at the Ponderosa Drive site.  The link below will take you to the action plan that we submitted to Mass DEP on 7/31/2015.

07-31-2015 Letter to Mass DEP outlining our action plan to manage TTHM's at Ponderosa Drive

As part of our action plan we contracted with a professional engineering firm, Weston and Sampson, to study the problem and submit a report to the state documenting their findings, results, conclusions, and recommendations.  This report may be viewed by clicking on the link below:

10-29-2015 Weston and Sampson Report on Total Trihalomethane Reduction for the Hanover Water System

Finally, based on Weston and Sampsons work, the DPW submitted articles to the May 2015 Annual Town Meeting to implement the recommendations of the Weston and Sampson report.  The Town Meeting appropriated funds and work is currently underway to design and construct necessary improvements to the Town's three treatment plants.  While the timetable is quite aggressive, we hope to have the design completed and approved by MassDEP sometime in the fall or early winter of 2016.   The project will be put out to bid shortly thereafter.

Please check back to this page for updates on our progress.


Water Quality and Transparency



The Hanover DPW is proactive in its quest to provide the highest quality of water possible. We are also committed transparency in our operations.   Please click on the following links for a narrative of the steps and tests that are performed to ensure the quality of the water over the past few years.  We also invite you to visit our water quality page for additional information on the quality of our supply and on our operations.  Finally, the following link will bring you to a management dashboard that is a window into the real-time operations of our treatment plants Water Treatment Dashboard.  This dashboard is a work in progress and we invite you to check back often as we work to enhance it:

2015 Consumer Confidence Report

2014 Consumer Confidence Report

2013 Consumer Confidence Report

2012 Consumer Confidence Report

2011 Consumer Confidence Report

2010 Consumer Confidence Report