Increasing Investigation Accuracy with Tracer Testing

Investigation of subsurface contamination migration is a challenging process, especially since we can’t see what’s underground with our own eyes. Tracer testing can give a view, of sorts, of what we can’t actually see.  Tracer tracing is, simply, injecting a tracer fluid into an aquifer to establish one or more of the following: Where and how the water is traveling, the velocity of which it is traveling, or if a sensitive surface water body may be receiving impacted groundwater. This method of investigation can give great insight into the behavior of a groundwater contaminant plume, and comes at a relatively small cost.

There are a wide variety of tracer fluids that can be used to study water flow. For instance, fluorescent dyes are very easily detectable and can be used for scenarios where there is insufficient lighting or a need for precise quantitative data.  These dyes can be fluorescein dyes, meaning they can be detected at very low concentration with a black light. Activated carbon samplers are used to calculate the concentration of a dye at a receptor location. Salt water tracers can track the time it takes water to move through an aquifer by measuring the changes in the electrical conductivity at several observation points.

How Dye Tracers Cut Investigation Costs

Tracer tests can give us a better understanding of the hydrogeology of a project site, especially in more complex situations.  They’re commonly used in situations where there is an abundance of fractures in the bedrock, making the calculation of groundwater flow more difficult. Without dye tracers, this scenario would call for more borings to be drilled to fill the data gaps, driving investigation costs up. A dye tracer test can provide the increased data density necessary when   developing a cost-effective remediation strategy, without the need for additional drilling.

Diagram of Dye Tracing During Investigation Phase

How Dye Tracer Tests are set up

Here’s how a tracer test works. First, we establish a monitoring network, starting from a release point, to a set of downgradient wells. Then, we select the dye we’d like to use, choosing the least reactive dye to the geological conditions to better mimic the groundwater flow. We then pick a measuring device (activated carbon sampler, electrical conductivity data logger), release the dye, and monitor.  Following the monitoring period and after all the data is collected and checked for quality control, calculations are completed and conclusions from the test information can be integrated into the CSM.


Helping Deliver Cost-Effective Remediation

Dye tracer testing is a useful way to save our clients and other project stakeholders money. It’s a cheap solution for scenarios where more data is needed to better understand the subsurface geology, and allows our team to pinpoint contaminant hot spots and exposure pathways with greater ease and accuracy, leading to more cost-effective cleaning solutions.

First Ever Hands-on Science Workshop with Herron High School a Success

Last week, we welcomed more than a dozen knowledge-hungry Herron High School kids to our Indianapolis headquarters for our inaugural Summer Science Workshop, and we could not be more excited for the future! The two-day program introduced these young minds to the daily operations of EnviroForensics, some down-to-earth talk about real-world scientific applications, and some helpful advice on kick starting a career in environmental science. The students arrived with open minds and a willingness to learn, and we hope they came away with something that will continue to fuel that intellectual curiosity.

Getting Into the Science of What we do

Over a two-day period, our team, under the ambitious direction of Project Manager, Casey McFall, put on nine different hands-on presentations for these burgeoning young scientists. Topics included soil and groundwater basics, remediation, vapor intrusion, as well as a short explanation of the sales and marketing side of our operation. Some highlights included project manager Michele Murday’s explanation of a cross-section using a 3-layer cake as a (tasty) visual, a hands-on demo of groundwater sampling event, a trip to one of our project sites (with explanation of the remediation systems from a safe distance), and Megan Hamilton’s visual presentation of vapor intrusion using burning incense, a fish tank, and a miniature house made of Legos. The idea of this workshop was to give the students some perspective on how the lessons they’re learning inside the classroom could apply to their future lives in the working world.

Nurturing an Interest in Science

When putting this science workshop together, we had no idea what kind of response we’d get from the students. They shattered even our most generous of expectations! They were smart, attentive, engaged, and curious. We conducted an already lengthy Q&A session at the end of the second day, and it still went 10 minutes over the allotted time. We’re so heartened and appreciative that these students came with such a passion to learn.

Developing an educational outreach program, like this, was something our founder and CEO, Steve Henshaw, had in mind when we moved into our headquarters last summer. The equipment warehouse (where the workshop took place) in the back of our building doubles as a learning lab where new field personnel, interns, and now high school students can come to learn the basics of environmental field sampling, or just brush up on their skills. This type of real-world experience is so valuable, especially to young people still trying to figure out what they want to do with their lives. This is a unique educational resource that we hope enriches our community. After all, an educated society is a properly functioning one, and we hope to be, in some small part, a guiding force behind that.

About Herron High School

Herron High School is a college preparatory charter high school located on the Near North Side of Indianapolis. The school provides a classical and liberal arts education to more than 700 students of varying cultural and socioeconomic backgrounds, and has been in operation since 2006.


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