map of martha's vineyard identifying the watersheds of the island.

Is a Permeable Reactive Barrier right for you?

One solution for combatting nitrogen runoff being introduced to island ponds.

Martha's Vineyard Commission

News on the Lagoon

01 / 05

What's New on the PRB?

Scroll to the right to find the latest happenings with the PRB including presentations and Lagoon Pond Site updates. Scroll down to find more in depth info on Permeable Reactive Barriers.

TWI hosts PRB presentation

 Tisbury Waterworks Incorporated with the MVC hosted Jessica Thompson, SMAST,  to discuss the PRB project residing on the  Lagoon in Vineyard Haven. Discussion included what PRBs are, what they can do for a nutrient rich ecosystem to reduce nitrogen input, and how the project on the Lagoon is going.

Jessica Thomas, PhD candidate presents PRB findings

 Jessica Thomas presents PhD  thesis presentation for Micro-Siting and Nitrogen Removal Efficiency of a Liquid Injection Permeable Reactive Barrier project to School for Marine Science and Technology on September 29th, 2021

In the News

Both the MV  Gazette  and the  Times  featured the Permeable Reactive Barrier in stories. You can find the links to each story by clicking on their respective names.

Micro-siting: Selecting the Lagoon for a PRB

PRBs require specific conditions to be effective so selecting the right location for this research oriented install was a crucial step.

What is a PRB?

A Permeable Reactive Barrier (PRB) is used to remove contaminants and nutrients from groundwater before it reaches a water body. They can be great to curb watershed loads and reduce nitrogen from groundwater.

On Martha's Vineyard PRBs will predominantly be used to reduce nitrogen from the groundwater before it makes its way to ponds.

Background picture description: graphic with permeable reactive barrier in place, limiting nitrogen runoff from groundwater sources.

The Problem of Nitrogen

Nitrogen is nutrient needed by plants to grow. It is a limiting nutrient in brackish ponds meaning the amount of nitrogen limits the amount of growth that occurs. When in excess, it can cause an abundance of growth that results in algae blooms that can harm other life living in those systems and makes water less aesthetically pleasing.

Nitrogen is introduced to watersheds in many ways and can be reduced at the source or captured before it reaches a water body. Nitrogen comes as a byproduct of septic tanks, through lawn fertilizers and agriculture, and from landfills, roads and other human made developments.

Background picture description: graphic of waterbody without permeable reactive barrier in place, with flow sources of groundwater.

What does a Permeable reactive barrier do?

A permeable reactive barrier allows groundwater to flow through it and removes nutrients and contaminants from the water.

Background picture description: map of Martha's Vineyard watersheds delineated by water body.

Chase and Sheri install a monitoring well in November of 2019.

Why install a PRB?

PRBs have been shown to reduce nitrogen load in groundwater significantly. When fully installed a Permeable Reactive Barrier lays flush to the ground and requires minimum maintenance and monitoring. If you're worried about a waterbody near you, consider a PRB to mitigate some of the nitrogen flowing into your ponds via the groundwater.

A Pilot Study on the Vineyard

01 / 07

A pilot study on the Vineyard

In 2019 a Permeable Reactive Barrier was installed on a property on Lagoon Pond. It required intensive site selection and regular testing and saw immediate results in nitrogen reduction after injection. Scroll to the right to see the steps taken in its creation.

Results

At the lagoon site, we've seen successful reduction of nitrogen from groundwater going through the permeable reactive barrier, reaching nearly 0mg/L of nitrate after passing through the barrier.

Monitoring

In order to know if the Permeable Barrier is effectively removing nitrogen from the groundwater, water is collected and tested upgradient and downgradient from the barrier.

Injection

Soybean and other oils are injected into the ground to bind and remove nitrogen from groundwater flowing through the permeable barrier. The oil is emulsified so it stays in place in the soil instead of flowing with the groundwater.

Installing the Wells

As this PRB project was selected as part of a research project, it has been monitored before, during and after injection of the PRB. Water is regularly tested for nitrogen content to determine effectiveness of the well.

Micro-siting

A PRB requires extensive parameters be met to be effective. In addition to PRB design and placement, the depth to groundwater, flow direction and hydraulic conductivity, as well as nitrogen concentration, soil type and any tidal influence on the groundwater need to be considered.

A Nitrogen Problem

The first step to installing a PRB is realizing you have a nitrogen problem in a waterbody near you or in your groundwater.

Chase and Sheri install a monitoring well in November of 2019.