Results are in and the groundwater in central Nikiski could be travelling in several different directions.
Researchers with DOWL HKM presented the results of a groundwater movement study commissioned by the Kenai Peninsula Borough to about 40 community members during a Monday meeting of the Nikiski Community Council.
The study area covered a mixture of residential, commercial, and industrial properties in addition to undeveloped land. The area tested was bordered at the north by the Cook Inlet near the Offshore Systems Kenai, OSK, dock, to the west by the eastern property line of Nikiski High School, the McGahan Industrial Airpark to the south and to the east by the western property line of the AIMM Technologies monofill site.
According to Alaska Department of Environmental Conservation records there are 13 contaminated sites within the study area — though the majority of them have completed cleanup requirements. The borough contracted with DOWL HKM to determine groundwater movement in the area in response to concerns expressed by some community members about the contaminated sites and the area’s water supply.
While researchers did not identify potential contaminant sources or how they moved through the groundwater, they did isolate and develop a three-dimensional geological model of the area which can be used in future studies.
“Ultimately if DEC or the borough want to use this to further examine the area … at least they’ll have a better foundation for what they’re looking at,” said DOWL HKM Environmental Specialist Zach Huff, after the meeting. “Hopefully they can take this data and help them plan more effectively for what they want to do.”
To build the model, the scientists used historical well log data and studies in combination with field studies done in November 2014 on 60 wells and four lakes, according to the DOWL HKM report. They identified two aquifers and were able to plot groundwater flow direction in one, but the other proved difficult to measure.
The deeper of the two aquifers, located between 50-75 feet above sea level is confined in an impermeable layer of silt and clay and consistently moves from the southeast to northwest, according to the study.
Several businesses and residences connect to that aquifer, including the North Kenai Baptist Church, Peak Oilfield Services, the Nikiski Post Office, Nikiski High School and the Village Trailer Court, according to the study.
The shallower aquifer is much less consistent in flow direction and researchers had a hard time finding data for it. Some of the wells at McGahan Utilities, the Nikiski airstrip, and Oilfield Salvage connect to that aquifer, according to the report.
“There aren’t many wells tapped into that,” Huff said. “Odds are, it’s flowing in multiple directions.”
That aquifer is less hydrologically connected, meaning that some areas could contain smaller, isolated bodies of water.
According to the report, contaminants that reach the lower aquifer would likely be transported in the general southeast to northwest direction. But contaminants in the upper aquifer could be moving in different directions depending on the several factors that affect water flow including how much water is being pumped into and out of the aquifer.
The borough’s $119,970 contract with DOWL HKM will eat up most of the $150,000 state money the borough received in 2013 for the project. However, DOWL HKM suggested a series of potential future studies and actions for the borough including:
— A public education campaign to help well owners learn how they can better protect their water wells at an estimated cost of $5,000-$10,000.
— Datalogger Installation which would install dataloggers to record groundwater elevations for extended periods of time in areas of interest at an estimated cost of $4,000 – $10,0000.
— Drawdown testing or pumping tests that could be conducted on wells near contaminated sites to determine the influence of well pumping on the water flow direction estimated to cost $8,000 – $12,000.
— Monitoring wells which could be installed on Kenai Peninsula Borough property, on the neighboring Arness disposal site or the former laundry on Nikishka Beach Road at a cost of about $10,000 – $30,000.
— Tracer identification and testing to identify chemical signatures specific to one or both of the aquifers in the area and sample wells in the study area at about $15,000 – $30,000
Regardless of whether the borough decides to do further testing, the researchers who presented the data in Nikiski told community members that all of their data and the model they had developed would be turned over to the borough for future usage.
Huff said one of the stumbling blocks researchers ran into was getting quality data out of previous studies and well logs available for the area. While the results of the studies were often available, the methodology used to generate those results was not. At times, it was unclear if the people gathering the data understood that there are two separate aquifers in the area, he said.
As a result, Huff said, the DOWL HKM model and study methodology would be available to anyone who wanted to use them.
“That’s always part of the problem. You get these studies and they say ‘these are our results and this is some of our data, use it as you want’ but it’s not very helpful,” Huff said. “All the hours that we put into collecting records online and all that stuff, that got sent to the borough … and then our model got sent to the borough.”
Reach Rashah McChesney at firstname.lastname@example.org or follow her on Twitter @litmuslens.