By Joseph Arsenault – Assistant Editor
University of Maine at Farmington (UMF) senior and Geology major Abby Berlin, who is currently working on senior research, shared part of her data to help a company in their decision of whether or not to divert the flow of the Sandy River from eroding a commonly used road in Farmington.
An environmental company, Jones Association, wants to remove sand from the river where there is currently an abandoned channel right now where the river used to flow, she said in a recent interview. According to Berlin they want to redirect the flow back because it is eroding closely to Whittier Road which is a main road in Farmington.
Since they wanted to remove sand they needed to know how much sand was there and so she provided the company with the data to confirm what they had already estimated. “It is actually useful to know what’s underneath the ground,” said Berlin.
Permits are needed to remove sand and gravel now and were not before, and Berlin said “It’s been a while since people have removed sand or gravel,” and they are trying to get a permit passed.
In a follow-up text after the interview Berlin said, “They already started removing the sand.”
Berlin mentioned another project being done on the Sandy River in relation to the redirection of the rivers channel. She said, “They are going to dig trenches into the river to put dogwood trees in the trenches with roots sticking out to collect silt to rebuild the cut bank.” Dogwoods last longer and they want to put the trees termed as “Root wads” where the river is eroding away near Whittier Road, she said.
The sand removal permit passed in Dec. 2011, and all of this occurred while Berlin was doing her senior research project with Ground Penetrating Radar (GPR) work.
GPR is a device with a transmitter on top of actual radar and it reflects back what is underground, she said, it is hooked up to a laptop and the laptop pops up with a graph of what is underneath the surface.
Berlin said she took a May term course with UMF’s Dr. Julia Daly and that is what lead to her senior research. During the class they used two different GPR devices, she said, and a “Total Station” was used which gave topographical data of the sites.
According to Berlin Topographical Total Station data can be plugged into the GPR software called “RadExplorer” which allows for elevation to be plotted.
As for the two different GPR devices, one is 100 MHz which is a larger GPR device that penetrates deeper into the ground with radar, but gives fuzzier images, and the other is a 500 MHz GPR device that doesn’t reflect images as deep, but allows for clearer images, she said.
With the information she said, the water table level and basal level, which is where the sand starts, can be found. Another piece of information seen is the “hyperbolics” and they show the reflection of where rocks and gravel are. The direction of deposition can also be seen.
For her research she said she has done topographical data at two gravel bars and two sand bars along the Sandy River. There was one particular bar she called the Voter gravel bar and she said there was once a river channel cutting across the bar in 2003, but as of now, that channel is abandoned. That GPR data unlike her information from the Pillsbury channel did not retrieve as much attention due to the fact that she shared her Pillsbury sand bar information with the environmental company.
She mentioned two separate point bars, as well as the Voter and one called Crandall. Those four sites are the areas for her research.
In her abstract found online she wrote, “Using GPR data, this project will quantify sand and gravel volume in these point bars and can estimate the percent removed in different mining scenarios.”
For her full abstract visit http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_200504.htm.