Remediating Groundwater Dioxane to Mitigate Marl Pond Degradation

Colebrook, New Hampshire

Featured image for the project, Remediating Groundwater Dioxane to Mitigate Marl Pond Degradation

Photo courtesy of the Town of Colebrook


The community of Colebrook, New Hampshire is a small, poor, rural community. It is a remote village located at the northern tip of New Hampshire. Colebrook has the highest unemployment in the State. Weather and climate is a factor.  It gets cold in Colebrook.  In January, temperatures will reach -40 degrees Celsius. 


The town’s closed municipal landfill has 1-4 Dioxane in the groundwater.  The levels present exceed Ambient Groundwater Quality Standards (AGQS).  The polluted groundwater has left the property boundary and is present on land of an abutter. 


The plume has resulted in groundwater degradation in the vicinity of Lime Pond located just across the municipal boundary in Columbia, New Hampshire.  This waterbody is an extraordinary example of a marl pond. Its bottom holds 6 feet of nearly pure, white marl, made up largely of shells of freshwater mollusks known as cyclas and planorbis that still live in the pond, usually under loose stones. The bedrock surrounding the pond is an impure, gray and blue limestone from which the calcium that defines the pond has leached over the past 10,000 years. 


To protect the pond, the Town was required to install a groundwater extraction system to collect groundwater.  This groundwater is then trucked across town to the municipal wastewater treatment system.  The Town then treats the groundwater as it does raw waste and discharges it into the Connecticut River.  The wastewater is treated with a system of aerators, SolarBees (mixers) and ultraviolet (UV) light. Locally, this system is referred to as a “pump and dump” method. 


Thus, the community has a groundwater dioxane problem associated with the landfill. Colebrook would like to know how they might determine a long-term, sustainable and cost-effective remedy.  The goal is to remediate the 1-4 Dioxane in situ (in place).


Becky and Dave will work together to provide a menu of remedies and costs for a “walk away” solution. The team anticipates that this project will take approximately 12 months. The primary deliverable(s) for this project will be a source characterization report and treatability studies.


TEX Partner, ICMA, highlights science impact in three ICMA communities

In their May 2017 of PM Magazine, TEX partner, the International City and County Management Association (ICMA), highlighted stories from three ICMA communities collaborating with TEX scientists. Bob Hart, formerly of Kennedale, TX (now with Corinth, TX), Laura Allen (Berlin, MD), and Becky Merrow (Colebrook, NH) describe how their scientific partners are helping their towns address critical community priorities. Click here to read the full article.

Colebrook team has their first meeting

All updates for this project

Project Team

Community Lead

Becky Merrow, Esq. earned her Bachelor of Science Degree in Paralegal Studies from Woodbury College (now Champlain College) located in Burlington, Vermont.  She has been working in public administration since the 1990’s.  She has been the Town Manager of Colebrook New Hampshire since 2012. 


Vermont has a unique program that allows individuals with a bachelor degree to “Clerk” for the bar.  Commonly referred to as “reading the law,” the program is an apprenticeship platform which takes 4 years to complete.  Upon successful completion, she was deemed qualified to sit for the Vermont Bar Examination and was sworn in as a member of the Vermont Bar Association in June of 2009.  This is the same manner that President Abraham Lincoln and Vermont Supreme Court Justice Marilyn Skoglund were allowed to practice law. 


Becky enjoys kayaking and travel and is passionate about the community she serves.  She is the grandmother of 5 year old Maggie Lorraine Newton.

Scientific Lead

Dr. David Ellerbroek serves as the Denver Area Manager for AECOM and oversee operations related to transportation, water, environment and urban facilities. He is passionate about natural resource development and have spent significant portion of my career working on methods to mitigate environmental impacts and protect water resources during natural resource development. My career has included international work for O&G and mining companies (Australia, Argentina, Peru and Chile), several large remediation projects including serving as Client Service for the El Paso Corporation remediation program and developing water management solutions for unconventional Oil and Gas development.

Scientist Wanted

Community Science Training Program

TEX is looking for a Fellow for our Colebrook, NH project! We are seeking a student or early career volunteer to work with a TEX scientist in support of a project in Colebrook, NH. The town’s closed municipal landfill has 1-4 Dioxane in the groundwater.  The levels present exceed Ambient Groundwater Quality Standards (AGQS).  The polluted groundwater has left the property boundary and is present on land of an abutter. 

The Fellow will have the opportunity conduct field sampling in at Skyline Drive, Colebrook NH for two (2) weeks in April 2018. S/he will have to commit to 40 hours a week for those two weeks.

Deliverable: A report for Colebrook’s Board of Selectmen. S/he might also have the opportunity to attend a Selectmen meeting.

This fellowship comes with a stipend courtesy of the Town of Colebrook and the Tillotson North Country Foundation. Thus, it is a full-time, paid opportunity with a set time commitment of 40 hours per week. It is intended to supplement the Fellow’s current employment or academic coursework.

It should be noted that the weather is quite cold in April and fieldwork will be intense with conditions potentially involving mud and/or snow.

In addition to engaging with the scientific mentor and supporting the TEX project, the TEX fellow will be asked to write at least two (2) blog posts on a topic of their choice concerning the TEX project and their role, working with communities, etc. TEX Fellows will be supported by TEX staff and AGU Student Programs.

Apply here

Please contact with any questions.

Applications due by 11:59pm Monday, 4 November.