HISTORY AND GEOLOGY OF THE NAVAL INDUSTRIAL RESERVE ORDNANCE PLANT (NIROP) NATIONAL PRIORITY LIST SITE, FRIDLEY, MINNESOTA
Friday, February 27th @ 4pm
Davis Hall room 308
By: Harvey D. Pokorny, PGNAVFAC Mid-Atlantic, Great Lakes, Illinois
The 83-acre Naval Industrial Reserve Ordnance Plant site (NIROP) lies approximately 700 feet east of the Mississippi River in Fridley, Minnesota. The U.S. Navy and its contractors produced advanced weapons systems at the industrial National Priority List (NPL) site from 1940 to 2012. In 1981, trichloroethene (TCE) was discovered in on-site groundwater wells and in the City of Minneapolis drinking water treatment plant intake pipe, located within the Mississippi River approximately 4,900 feet downgradient from the NIROP site. In 1983, investigations identified pits and trenches in the "North 40" area of the NIROP site where drummed wastes had been disposed. Contaminated soil and drums have since been excavated from the "North 40" area and properly disposed off-site.
In August 1988, a remedial investigation and feasibility study revealed that impacted groundwater originating from the site was flowing towards the Mississippi River at TCE concentrations of up to 10,000 parts per billion (ppb). In contrast, the Safe Drinking Water Act sets the maximum contaminant limit (MCL) at five ppb PCE for potable water. Concentrations of TCE in area monitoring wells adjacent to the river have since decreased to levels ranging between non-detect to 150 ppb, and TCE has not been detected in the city of Minneapolis water intake pipe since the 1980s.
On September 28, 1990, EPA issued a Record of Decision (ROD) that presented a cleanup remedy to hydraulically contain the groundwater contaminant plume using an extraction well system. The Navy conducts cleanup and groundwater monitoring action at the NIROP site through a partnering arrangement with the U.S. EPA and the Minnesota Pollution Control Agency (MPCA).
Groundwater treatment has been ongoing at NIROP since September 1991 and continues today. Additional extraction wells were installed, replaced, and/or taken out of service over the years, along with treatment system upgrades designed to maximize system performance and gather additional information. More than 4.3 billion gallons of groundwater have been treated since 1991, resulting in a recovery of over 40,000 pounds of TCE. The treatment system is removing contaminants between 25 and 100 feet in depth, but will take excessive time for groundwater to reach cleanup goals at the current pace.
Groundwater remediation at the site is complicated by glacial drift sediments intertwined with fluvial terrace channels on the east and stacked channels closer to the Mississippi River edge. The Navy is completing a source investigation featuring vertical sampling at 36 locations. A preliminary overview of investigation results will be presented along with the geologic framework of the site.
Harvey D. Pokorny, PG
Mr. Pokorny, a Professional Geologist, is a native of the Chicago area. He spent the initial 13 years of his geological career in the oil and gas business working as an exploration geophysicist/geologist. Work was performed for independent oil and gas firms both as a consultant and employee.
Since 1989, he has been employed in the environmental business as a geologist/project manager. He has conducted Phase I environmental assessments through completion of remedial action on multiple sites in multiple states. The past seven years were spent with an emphasis on environmental oversight of construction projects. This work continues with his present employer, NAVFAC Mid-Atlantic, located at Naval Station Great Lakes.
Mr. Pokorny’s area of expertise is the geological sciences and application of same to the environmental industry. He brings in a background of chemistry and regulatory compliance to project management issues.
He received a Bachelor of Science (1970) and Master of Science (1972) in Geology from Northern Illinois University. He trained in the environmental sciences at Colorado School of Mines. He is a licensed professional geologist in Indiana and Illinois, a Certified Geologist of American Institute of Professional Geologists, and an active member of the American Association of Petroleum Geologists.