LYNDONVILLE – The public can weigh in on a proposed cleanup plan for Monroe Electronics, which is part of the state’s Superfund Program.The DEC will discuss the cleanup plan during a 6:30 p.m. meeting on Jan. 7 at Village Hall, 2 South Main St. The state will also accept comments about the project until Jan. 22.

Monroe Electronics is located at 100 Housel Ave. The company has operated from the site since 1972, manufacturing electrostatic measuring instruments and other electronic devices. Before Monroe Electronics operated here, the property was the site of the former DuPont/Barre Lime and Sulfur Company where various pesticide sprays and dust mixtures were manufactured, according to the DEC.

In September 1986, Monroe Electronics submitted a Hazardous Waste Disposal Questionnaire as a requirement of the Community Right-to-Know survey. Monroe Electronics indicated that it dumped 1 to 4 tons of TCA at the Housel Avenue facility outside a former door on the west end of the building in the early 1970s. The owner indicated that TCA and waste oil was spread along the driveway on the east side of the building.

A remedial investigation was completed in multiple phases between 2011 and 2014 and included installation of over 30 soil borings and monitoring wells. Several monitoring wells were constructed in “clusters” to monitor groundwater quality in the overburden (shallow and deep) and the upper bedrock zones.

The drilling program also included installation of five soil borings inside the active manufacturing building. Field investigations included testing of soil, groundwater, surface water, sediment, soil vapor, and indoor air both on-site and off-site to define the nature and extent of contamination.

The contaminants of concern at the Monroe Electronics site include industrial solvents in groundwater and arsenic in soil. The two specific industrial solvents known to be causing environmental impacts at the site are 1,1,1-trichloroethane (TCA) and trichloroethene (TCE). TCA and TCE are chlorinated volatile organic compound (VOCs) that were used for cleaning and degreasing components in the manufacturing process. These two chemicals, as well as their by-products of degradation, have been detected in groundwater at concentrations above Class GA  Groundwater Standards and Guidance Values.

Based on the results of groundwater sampling conducted to date, it is clear that the overburden and bedrock aquifers beneath the site are contaminated by chlorinated VOCs originating from one of two subsurface sources: 1) a source of TCE near the gravel parking area at the east end of the building, and 2) a source of TCA located at the west end of the building.

These dissolved contaminant plumes are thought to be co-mingled at some point beyond the northern property boundary and undergoing limited reductive dechlorination. As a result, the extent of VOC contamination in groundwater off-site appears to be limited to the area near the site and does not extend far beyond West Avenue to the north, the DEC said.

The DEC, in consultation with the state Department of Health, developed the proposed remedy after reviewing the detailed investigation of the site and evaluating the remedial options in the “feasibility study” submitted under the state’s Superfund Program.

The site is listed as a Class “2” site in the State Registry of Inactive Hazardous Waste Disposal Sites. A Class 2 site represents a significant threat to public health or the environment and action is required, the DEC said.

The remedy proposed for the site includes:

Enhanced In-Situ Bioremediation, involving multiple injections of bioamendments and degrading bacteria into the bedrock aquifer, to treat chlorinated volatile contaminants in groundwater beneath the manufacturing building and immediately downgradient;

In-Situ Chemical Reduction, involving injections of liquid-phase reducing agents (e.g., zero-valent iron) to supplement the bioremediation groundwater remedy and boost the rate of abiotic destruction of organic contaminants in groundwater;

A vegetated soil cover in areas where surface soil exceeds the applicable soil cleanup objectives for arsenic. The soil cover will be a minimum of one foot of soil placed over a demarcation layer (e.g. a layer of orange snow-fencing), with the upper six inches of soil of sufficient quality to maintain a vegetative layer;

Indoor air monitoring program to address potential exposures related to soil vapor intrusion during and following the active remediation phase;

An environmental easement that will restrict use of the site to commercial or industrial purposes in conformance with local zoning laws, prohibit use of any structure on the site for residential purposes, restrict use of groundwater for potable or process water, and require compliance with the approved Site Management Plan;

Development of a Site Management Plan, approved by the DEC, to ensure that the institutional and engineering controls are properly implemented and monitoring requirements adhered to.

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