Guaranteed Remediation of COCs in Soil under a Building Confidential Client – Hudson River Valley, New York

Project Summary TRS Group, Inc. (TRS) completed a Guaranteed Fixed Price Remediation (GFPR) of CVOCs in soil, including 1,1,1-trichloroethane (TCA), 1,2-dichloroethane (1,2-DCA), 1,1-dichloroethene (DCE), 1,1-dichloroethane (1,1-DCA), tetrachloroethylene (PCE), and trichloroethene (TCE) associated with a former waste TCA tank in Hudson Valley area of New York. The goal of the ERH remediation system was to:

Remove and/or treat DNAPL located in the SWMU S treatment area, to the extent practicable, that serves as a source of impact to downgradient groundwater

In addition to achieving the Remedial Action Objectives (RAO) of <1 mg/kg in soil, the remedial contractor shall demonstrate that concentrations of SWMU S compounds of concern in soil within the treatment area meet NYSDEC Subpart 375-6 Soil Cleanup Objectives for Commercial Use

Originally contemplated short-term groundwater RAOs were not required by NYSDEC due to the presence of background groundwater impacts

The ERH system removed approximately 400 gallons (4,000 pounds) of DNAPL. In addition, approximately 5,000 lbs of TCA was remediated in the subsurface due to hydrolysis.

Background

The site is a former manufacturing facility where operations ceased in early 1990s and the property was subsequently subdivided into multiple parcels. The site was sold in 1998. SWMU S comprises a former 4,000-gallon TCA waste underground storage tank (UST) and an associated 1,000-gallon supply UST, both co-located on the west side of Building B001 (Figure 1). These were steel tanks installed circa 1955 and used in the manufacturing operations through 1967.

Figure 1. Treatment area overview

ERH combined w ith hydrolysis exceeds remediation goals w ith only 78% of design energy input.

KIN41 ShortV ProjEx 070615

Remedy evaluation was conducted using the following parameters: Short-term Effectiveness, Long-term Effectiveness, Reduction of Toxicity, Mobility or Volume of Contamination, Implementability, Cost effectiveness, and Land Use. At conclusion ISTD using ERH technology was selected to meet the RAO for the SWMU S area based on the following:

• ISTD has the shortest implementation schedule

• ISTD is likely to achieve the RAO for SWMU S o in a single treatment without pilot testing, o therefore expediting remedy implementation

• Remedy effectiveness can be evaluated shortly o after treatment completion

Site Characteristics & Design Parameters

The stratigraphy across the site contains the following three primary lithologic units: • Surficial Sand Unit from surface to depths ranging from approximately 17-25 ft bgs. • Transition Zone consisting of gray silt, sand and clay at varying depths from 17-25 ft bgs. • Varved Clay Unit consisting of red-brown and gray clay with intermittent silt zones typically encountered at 23-28 ft

bgs. Depth to groundwater is 6-7 feet with a groundwater flow of 0.8 to 2.0 ft/day. TRS modeled the remediation using 11 compounds (TCA; 1,1,2-TCA; 1,1-DCA; 1,1-DCE; 1,2-DCA; Freon 113; PCE, TCE, 1,2-DCE, toluene and xylenes) at the highest concentrations observed in site soil samples and also using anticipated PCE concentrations in soil from the DNAPL analysis. The results showed three compounds (TCA; 1,2-DCA and PCE) to be the controlling CVOCs that drive the clean-up time-frame due to a combination of concentration, boiling point, and clean-up goals. The models showed similar clean-up energy demands and time-frames with the compound 1,2-DCA requiring slightly more time and energy than the others to achieve clean-up due to the low remedial concentration objective of 1 µg/L. Although 98% of the mass is TCA, it is more readily hydrolyzed to 1,1-DCE and stripped than other compounds. The overall site model was therefore prepared using the more conservative 1,2-DCA value. The overall treatment area is 8,500 ft2, with a depth interval from 2 – 32 ft resulting in a treatment volume of 9,400 yd3. The site was then broken into the following two treatment areas for modeling based on CVOC concentrations as illustrated:

1. 3,600 ft2 source area defined by groundwater CVOC concentrations exceeding 10% of solubility, and 2. 4,900 ft2 periphery area defined by groundwater CVOC concentrations in the range of 1% to 10% of solubility.

The combination of the MIP soil and groundwater response data and residual DNAPL calculations indicate that the site contains an estimated 26,335 pounds of CVOCs (14,371 lbs. absorbed and dissolved plus 11,964 lbs DNAPL).

Hydrolysis Hydrolysis is a water substitution reaction. TCA is the easiest chlorinated alkane to hydrolyze. It has a degradation half-life of approximately one day at 65°C. The azeotropic boiling point of TCA in contact with water is also 65°C. Therefore, TCA sites will see significant quantities of TCA mass hydrolyzed in place in addition to the mass that is volatilized from the subsurface. The first step of the hydrolysis reaction is a substitution reaction where a chloride anion is substituted with a hydroxide anion extracted from the water:

CH3CCl3 + H2O CH3CCl2OH + HCl (1-hydroxy-1, 1-dichloroethane)

The 1-hydroxy-1, 1-dichloroethane is very unstable and reacts quickly with water either by a substitution or elimination pathway. Hydrolysis by substitution is the primary pathway and approximately 80% of the 1-hydroxy-1, 1-dichloroethane will convert into acetic acid by reaction through this pathway.

CH3CCl2OH + H2O CH3COOH + 2HCl (acetic acid)

The remaining 20% of 1-hydroxy-1, 1-dichloroethane proceeds by an elimination pathway to produce 1, 1-DCE which is then recovered by steam stripping.

CH3CCl2OH CH2CCl2 + H2O (1,1-DCE)

KIN41 ShortV ProjEx 070615 ©2015- TRS Group®, Inc. All rights reserved.

System Construction/Operations TRS installed 61 dual-element electrodes to a depth of 34 feet below grade surface (ft bgs). System installation required 94 days to complete. A figure showing electrode layout is shown as Figure 2. The electrodes have a variable spacing with slightly tighter spacing in the most impacted portions of the site and slightly wider spacing at less contaminated portions of the site. This design allows TRS to increase power and energy to portions of the site that require more energy to reach the cleanup goals. A tighter spacing incorporated within the design for this project provided the necessary power density to overcome any heat loss associated with a high groundwater flux through the upper sand interval. TRS installed six temperature monitoring probes (TMPs) to provide continuous temperature data collection within the subsurface treatment volume. Temperature data was automatically collected at each TMP starting at five ft bgs and extending to the bottom of the treatment volume. The system equipment consisted of the following: one 40-hp vacuum blower, one steam condenser with dual cooling towers, one 2,000 kW power control unit (PCU), and one steam regenerated granular activated carbon (SRGAC) treatment unit (Figure 3 below).

SRGAC was the ideal vapor treatment method due to high expected contaminant mass and the poor loading rates of 1,1-DCE. A typical vapor phase granular activated carbon (VGAC) requires on-site change outs of carbon and off-site regeneration. The labor and fees for this can become significant for sites with increased mass. SRGAC allows for on-site regeneration via steaming. This process creates a condensate water stream that is recycled to the condenser and a DNAPL stream which is sent to a tank for storage and subsequent disposal. 1,1-DCE, does not load well on VGAC and would have require multiple change outs during the life of the project. The added cost of the multiple VGAC change outs makes the SRGAC a financially attractive option to treat high mass sites, as the vessels can be regenerated on site multiple times a day allowing for fresh carbon vessels and peak removal efficiencies.

Figure 3. SRGAC

Figure 2. Electrode layout

KIN41 ShortV ProjEx 070615 ©2015- TRS Group®, Inc. All rights reserved.

A motion detecting security system and security chain link fence were installed around the perimeter of the treatment area. The safety and security system turns off the ERH energy application and immediately notifies TRS in the event of an unauthorized intrusion. In addition, multiple video camera was mounted at the site (see Figure 4 below). Upon notification of an alarm, TRS could immediately view the video footage and determine the cause of the alarm remotely. The security system was also linked to the local police for immediate notification if an unauthorized intruder was detected. Results The ERH system operated for 96 days and required 94 days to install consisting of a total 190 days to complete. The ERH system successfully remediated the site to the RAO soil goals of 1 mg/kg or less. Initial starting soil concentration were estimated to range from 56 mg/kg to 35,000 mg/kg. The site was able to achieve the site cleanup goal while applying only 78% of the estimated energy to the treatment volume. The ERH system removed approximately 400 gallons of DNAPL or 4,000 lbs. In addition, approximately 5,000 lbs of TCA was remediated in the subsurface due to hydrolysis.

Summary

TRS Contact Information Mr. David Fleming, (425) 396-4266, dfleming@thermalrs.com, www.thermalrs.com

Site Geology and Hydrology 3 zones: Sand, silt, clay. Groundwater, 6-7 ft bgs

Treatment Area Size, Volume, and Depth 8,500 ft2; 9,400 yd3; 2 to 32 ft bgs

Beginning Maximum Contaminant Concentrations 1,1,1-TCA – 35,000 mg/kg, 1,1-DCE – 820 mg/kg, 1,2-DCA – 56 mg/kg, 1,1-DCA – 89 mg/kg, PCE – 245 mg/kg, TCE – 644 mg/kg, toluene – 120 mg/kg, xylenes – 120 mg/kg

Remedial Goal(s) 1 mg/kg for each site VOC

Reduction Achieved/Remedial Goal Achieved >99.999% for 1,1,1-TCA

Period of Performance 96 days of operation

Contract Terms Guaranteed Fixed Price Remediation

Figure 4. Site Security

KIN41 ShortV ProjEx 070615 ©2015- TRS Group®, Inc. All rights reserved.