Table of Contents

2020 RDS and CDS Annual Report Table of Contents

Executive Summary

1. Introduction

• 1.1 Purpose
• 1.2 Environmental Monitoring Objectives 2020

2. General Site Information

• 2.1 Former Radiation Disposal Site
  • 2.1.1 Site History and Description
  • 2.2.2 Remedial Measures
• 2.2 Former Chemical Disposal Site
  • 2.2.1 Site History and Description
  • 2.2.2 Remedial Measures

3. Site Activities in 2020

• 3.1 Operation, Maintenance, and Monitoring of Final Remedial Measures
• 3.2 Reports Submitted to the NYSDEC
• 3.3 NYSDEC Approvals and Permits Issued
• 3.4 Public Participation
• 3.5 NYSDEC Inspections

4. Monitoring Overview

• 4.1 Sample Collection and Analysis
• 4.2 RDS Groundwater and Surface Water Monitoring
• 4.3 CDS Groundwater and Surface Water Monitoring
• 4.4 Monitoring and Remedial Measures
• 4.5 Groundwater Treatment Plant Monitoring

5. Geologic, Hydrologic, and Climatological Setting

• 5.1 2020 Climate Summary
• 5.2 Geology and Hydrology
• 5.3 Hydrogeology

6. RDS Monitoring Results

• 6.1 Groundwater Monitoring
  • 6.1.1 Laboratory Analysis
  • 6.1.2 Conclusions
• 6.2 Surface Water
• 6.3 Recommendations for 2021

7. CDS Monitoring Results

• 7.1 Groundwater Monitoring
  • 7.1.1 Chemical Analysis
  • 7.1.2 Conclusions
• 7.2 Surface Water
  • 7.2.1 Chemical Analysis
  • 7.2.2 Conclusions
• 7.3 Recommendations for 2021

8. Remedial Measures

• 8.1 RDS Source Control System
  • 8.1.1 Water Testing Results
  • 8.1.2 Operation, Repair, and Maintenance
  • 8.1.3 Conclusions
  • 8.1.4 Future Plans for Source Control
• 8.2 RDS Groundwater Recovery System
  • 8.2.1 Chemical Evaluation
  • 8.2.2 Conveyance Line Inspections
  • 8.2.3 Operation, Repair and Maintenance
  • 8.2.4 Recommendations and Future Plans
• 8.3 CDS Source Control System
  • 8.3.1 Hydraulic Evaluation
  • 8.3.2 Chemical Analysis
  • 8.3.3 Conclusions
  • 8.3.4 Recommendations and Future Plans
• 8.4 CDS Plume Collection System
  • 8.4.1 Hydraulic Evaluation
  • 8.4.2 Chemical Analysis
  • 8.4.3 Operation, Repair and Maintenance
  • 8.4.4 Conclusions
  • 8.4.5 Recommendations and Future Plans
• 8.5 Groundwater Treatment Plant
  • 8.5.1 Flow Evaluation
  • 8.5.2 Laboratory Analysis
  • 8.5.3 Hazardous Waste Generated
  • 8.5.4 Repair and Maintenance
  • 8.5.5 Conclusions
  • 8.5.6 Recommendations
• 8.6 Summary of Operations, Recommendations for 2021, and Future Plans

9. References

Tables

Figures

Appendices

Executive Summary

2020 Annual Report
Radiation and  Chemical Disposal Sites
Cornell University
Lansing, New York

Executive Summary

This annual report summarizes the monitoring and other remedial activities undertaken in 2020 at Cornell’s former Radiation Disposal Site (RDS) and Chemical Disposal Site (CDS) located north of the Ithaca Tompkins Regional Airport on Snyder Road, Town of Lansing, Tompkins County, New York. Cornell is remediating these sites under Consent Orders with the NYSDEC. Additional information on site activities can be found at the disposal sites website.

Hydrogeological and Climatological Conditions for 2020:

• Precipitation during 2020 was 0.49 inches below normal, or about 99% of normal.
• Groundwater elevations and flow directions were similar to those in previous years.

Radiation Disposal Site Monitoring Activities Summary for 2020:

• Monitoring at the RDS in 2020 included water level measurements, and groundwater and surface water sampling and analysis.
• Average paradioxane concentrations in groundwater in 2020 were generally below the average concentrations observed prior to installation of RDS remedial measures in 2003 and 2004.

Chemical Disposal Site Monitoring Summary for 2020:

• Monitoring at the CDS in 2020 included water level measurements, and groundwater and surface water sampling and analysis.
• The groundwater plume of total volatile organic compounds (VOCs) remained relatively stable in terms of chemicals detected and areal extent over the past year. Trichloroethylene (TCE) was the contaminant detected in highest concentrations and most frequently in monitoring wells and exceeded the NYS Ambient Water Quality Standard (AWQS) of 5 μg/L one or more times in 6 of the monitoring wells sampled in 2020 Other compounds detected in groundwater above AWQS in one or more wells during 2020 included 1,2-Dichloroethane and cis-1,2-Dichloroethene.
• Peak VOC concentrations in the center of the CDS-PCS were similar to those seen in recent years but remained lower than the typical values seen during the several years prior to completion of remedial measures. The plume remained similar in terms of location and areal extent. Peak concentrations remained within a long-term downward trend.
• Surface water samples taken semiannually during 2020 from the drainage ditch southwest of the plume collection system on airport property exhibited low levels of Trichloroethene at concentrations below the NYS AWQS of 5 μg/L.

Remedial Measures Monitoring Activities Summary 2020:

• RDS Source Control System monitoring included water level measurements near the barrier wall and cap inspections.
• Water level monitoring indicated that a hydraulic connection remains between the inside and the outside of the RDS barrier wall.
• There was a general decrease in paradioxane concentrations in groundwater near the disposal area compared to data collected prior to barrier wall installation.
• The RDS Groundwater Recovery System was operational throughout 2020. The system operated in response to the paradioxane concentrations (above 50 μg/L) in groundwater south of Snyder Road.
• CDS Source Control monitoring included measurements of the water level in well couplets inside and outside the barrier wall, inspection of the cap, and measurements of flow from the Source Control System (SCS) to the Groundwater Treatment Plant.
• The CDS SCS operated as designed. An inward hydraulic gradient was maintained across the barrier wall around the disposal site throughout the year.
• Both the CDS and RDS capping systems continued to be effective at preventing direct contact with the wastes and reducing infiltration of precipitation.
• The CDS PCS, consisting of the deeper extraction well system, was effective in maintaining hydraulic control of the groundwater plume on airport property.  Operations at extraction well EP-2 and EW-3 were discontinued as planned.
• Groundwater Treatment Plant monitoring included flow and pH measurements and monthly sampling of the effluent from the plant and the influent from the RDS groundwater recovery system, the CDS SCS and the CDS PCS.
• During 2020, the Groundwater Treatment Plant processed a total over 2 million gallons of water from the RDS, PCS and SCS.
• The Groundwater Treatment Plant operated effectively during 2020 and met the discharge requirements established by the NYSDEC.
• Ten drums of hazardous waste were generated from the treatment of groundwater at the GWTP in 2020.
• The GWTP discharged approximately 0.102 mCi of radiation (1.1% of the permitted annual activity) during 2020.

Future Plans and Recommendations:

• Plans for 2021 include continued environmental monitoring and performance monitoring of the remedial measures, in accordance with the integrated site management plan that governs ongoing operation, maintenance, and performance monitoring activities related to the CDS and RDS.
• Sampling/analysis for low-level 1,4-dioxane will continue as requested by NYSDEC.
• Review of existing operations, maintenance & monitoring and the subsequent refinements, at both the GWTP and the field collection systems will remain a top priority.

1. Introduction

1.1 Purpose

Cornell University owns two inactive hazardous waste sites located in Lansing, New York. The former Chemical Disposal Site (CDS) is a one-acre site that was used for the disposal of Cornell’s laboratory waste chemicals from 1962 to 1978 (Figure 1-1). The former Radiation Disposal Site (RDS) is a two-acre site that was used for the disposal of low-level radioactive waste (LLRW) generated by Cornell from 1956-1978.

Cornell University has entered into Orders on Consent with the New York State Department of Environmental Conservation (NYSDEC) governing investigation and cleanup of both sites. Order on Consent Index #A7-0289-92-10 governs work at the CDS and Order on Consent #A7-0333-95-08 governs work at the RDS. Both sites are managed under the Site Management Plan prepared by Cornell University.

This report, which documents monitoring and other remedial activities conducted in 2220, serves as the Periodic Review Report (PRR) under the Site Management Plan for both sites. This report also fulfills the annual reporting requirements of the Consent Orders for the calendar year for both the RDS and CDS. In addition to compilation in this annual report, monthly Discharge Monitoring Reports for the CDS and quarterly Part 380 Status Reports for the RDS also have been submitted to the State, as required under the NYSDEC Effluent Limitations and Monitoring Requirements #75002 for the CDS and the Substantive Part 380 Permit for the RDS.

The annual report is organized in nine sections.

• Section 1 includes the introduction with the purpose and objectives of environmental monitoring at the sites.
• Section 2 includes general site information, including site history, previous investigations, and a description of remedial measures completed at each site.
• Section 3 includes related site information, including reports submitted to the NYSDEC during 2020, approvals and permits, public participation activities, and a summary of NYSDEC inspections.
• Section 4 provides an overview of monitoring performed at the sites.
• Section 5 summarizes 2020 climatological and hydrogeological data for both sites.
• Section 6 summarizes 2020 monitoring results at the RDS.
• Section 7 summarizes 2020 monitoring results at the CDS.
• Section 8 summarizes 2020 monitoring results from the remedial measures in place at both sites.
• Section 9 contains references.

1.2 Environmental Monitoring Objectives 2020

The objectives of the monitoring programs at both sites are to:

• Monitor environmental media to assess any changes in site conditions,
• Obtain necessary information to evaluate the performance of the remedial measures, and
• Comply with the requirements of the Substantive Part 380 Permit (February 3,2003, renewed 12/3/2007, renewed 10/21/2014) and Substantive SPDES Permit 755002 Outfall 001 (July 17, 2002, extended 12/29/2006, reissued March 20,2009).

2. General Site Information

2.1 Former Radiation Disposal Site

2.1.1 Site History and Description

The Cornell University former RDS is a 290-foot by 300-foot disposal area surrounded by a fenced enclosure located on Snyder Road, north of the Ithaca Tompkins Regional Airport, in the Town of Lansing, Tompkins County, New York (Figures 1-1 and 2-1). This facility was utilized from 1956 to 1978 as a disposal area for low-level radioactive waste and associated materials generated by Cornell. Waste materials were disposed in trenches 6 to 12 feet deep.

During remedial investigations for the RDS, 34 groundwater monitoring wells and 42 surface water sampling locations were established to evaluate the nature and extent of contamination. Remedial investigations concluded that groundwater and surface water are the affected media in the RDS investigation area. Radionuclides (strontium-90, carbon-14, and tritium), paradioxane, dichloroethylene (DCE), and benzene are the contaminants of concern in the groundwater, and paradioxane is the contaminant of concern in the surface water. Identification of these contaminants of concern was based on contaminant mobility, potential health effects, frequency and distribution of detections, and comparison to background levels of radionuclides. Paradioxane is the most extensive contaminant in groundwater. The groundwater contamination is predominantly in the highly fractured shale zone, with paradioxane detected in groundwater in this zone approximately 2,500 feet downgradient from the disposal area. Paradioxane has been detected in surface water primarily north of Snyder Road and on airport property, although it also has been detected occasionally further downstream.

The RDS is being remediated under a 1996 Consent Order (NYS Hazardous Site Index #755001) with the New York State Department of Environmental Conservation (NYSDEC) (Index # A7-0333-95-08). A Record of Decision (ROD) selecting the final remedy was issued by the NYSDEC in March 2002.

Interim Remedial Measures (IRMs) to limit surface water infiltration into the waste at the RDS (Capping IRM) were performed in 1996-1997. A Groundwater IRM to capture paradioxane was constructed in 2001, and operated from 2002-2007 and from 2011-present. The final Source Area Remediation specified in the ROD was completed during 2004. These remedial measures are described in more detail below.

2.1.2 Remedial Measures

RDS Capping IRM

In 1996-97, capping IRMs were performed at the RDS that included: covering the disposal area with a high-density polyethylene cap system with gas vents; grading the area to provide surface water diversion and erosion protection systems; and installing a below-ground conveyance line to transport RDS site related water to the Groundwater Treatment Plant located near the CDS, approximately one-third mile to the southeast of the RDS. The Capping IRM eliminated volatilization, surface runoff, surface water infiltration, and direct contact as potential contaminant migration pathways.

Groundwater Recovery System

A Groundwater Recovery System to control the migration of the paradioxane plume emanating from the site was constructed as an IRM in 2001, and began operating on August 19, 2002. With the issuance of the ROD, this became part of the Final Remedy for the site. The Groundwater Recovery System consists of a series of 13 recovery wells on the north side of Snyder Road and monitoring wells to monitor its effectiveness upgradient, downgradient and between the recovery wells. The recovery wells pump contaminated groundwater to the Groundwater Treatment Plant, via the below ground conveyance line. Water from the site is treated using ultraviolet oxidation to remove paradioxane from the water.

Source Area Remediation

The ROD for the site specified a Final Remedy which included source area containment measures consisting of a grout curtain in the bedrock, a soil-bentonite wall in the soil layer, and a multi-layered capping system. Installation of these measures was completed during 2004. The grout curtain and soil-bentonite wall are intended to minimize transport of contaminants from the site via groundwater, while the cap is intended to prevent contact with the waste materials and to prevent infiltration of water into the waste.

2.2 Former Chemical Disposal Site

2.2.1 Site History and Description

Cornell University’s former CDS is also located north of the airport on Snyder Road, in the Town of Lansing, Tompkins County, New York (Figures 1-1 and 2-1). Waste chemicals were managed at the site in nine disposal cells by various techniques, including burial in trenches; open burning with burial of the residue; mounding; and evaporation (Figure 2-2). Cornell University operated the site from 1962 to 1978 in accordance with acceptable practices at the time.

During remedial investigations at the CDS, fifty-seven groundwater wells, twelve piezometers, and sixteen extraction wells were used to characterize, define, monitor, and control the chemical plume and the disposal site groundwater (Figure 2-1). Groundwater contamination, primarily from trichloroethylene (TCE) and other volatile organic compounds (VOCs), has been detected primarily in the two shallow zones (glacial till and fractured shale). The groundwater contamination is predominantly in the fractured shale zone, extending approximately 2,500 feet southwest of the disposal site.

Between 1990 and 1992, interim remedial measures (IRMs) were designed and constructed in accordance with NYSDEC Consent Order #T042887, as amended on March 25, 1992. The IRMs included a Source Control System (SCS) for the disposal area and a Plume Collection System (PCS) for contaminated groundwater downgradient of the site. These IRMs are further described in section 2.2.2.

In December 1998, the PCS was upgraded to prevent the migration of contamination beneath and past the initial groundwater collection trench. This project was referred to as the CDS Trench Upgrade, and is further described in Section 2.2.2. This work was performed in accordance with a new NYSDEC Consent Order (Index # A7-0289-92-10), dated August 19, 1998, that incorporates the requirements of the earlier Consent Order by reference and formalizes the previously issued ROD for the site.

During 2004, Cornell completed installation of the remedial measures required under the Order on Consent (Index #A7-0289-92-10) and the subsequent ROD by installing a concrete capping system for the cylinder burial area and an engineered cap covering the landfill.

Cornell University is currently operating and maintaining these remedial measures, which are designed to control and remove VOC contamination from groundwater in and around the site, as well as to prevent further releases from the former disposal area. The groundwater treatment plant, which treats contaminated groundwater pumped by the IRMs, operates in accordance with NYSDEC Effluent Limitations and Monitoring Requirements #755002.

2.2.2 Remedial Measures

CDS Source Control System

The SCS was designed to minimize the release of contaminants from the former chemical burial site. It consists of a groundwater barrier wall, a groundwater extraction system, and a capping system. The soil-bentonite groundwater barrier wall surrounding the one-acre site extends into the upper fractured shale bedrock. Pumping from four groundwater extraction wells, located inside the four corners of the enclosure, controls migration of contaminants by maintaining an inward hydraulic gradient across the groundwater barrier wall. A concrete containment structure covers an area containing buried gas cylinders. The entire source area is covered with a multi-layer impervious capping system with soil and vegetation at the surface.

CDS Plume Collection System

The PCS was designed to prevent further migration of, and reduce contaminant concentrations in, the CDS groundwater plume. It consists of a groundwater collection trench and extraction wells, which control the plume by pumping contaminated groundwater for treatment at the groundwater treatment plant, located adjacent to the former one-acre disposal area. Two scavenger wells (SW-1 and SW-2) are located at what once were the more highly contaminated locations within the plume. The collection trench, which is approximately 900 feet long and 8 to 14 feet deep, is located near the downgradient boundary of the plume. Three extraction points (EP-1 to EP-3) are located inside the trench. This portion of the Plume Collection System is known as the PCS Shallow recovery system (PCS-Shallow).

To recover the deeper portion of the plume in groundwater from the upper portion of the bedrock (10 to 40 feet below land surface), seven extraction wells (EW-1 to EW-7) were installed in December 1998 immediately downgradient of the collection trench. Known previously as the PCS Trench Upgrade, this system is now referred to as the PCS-Deep recovery system (PCS-Deep). Contaminated groundwater from the three extraction sumps in the trench and the two scavenger wells is combined and pumped to the treatment plant. Water from the seven extraction wells is combined in a second pipeline and conveyed to the treatment plant where it joins with the PCS-Shallow system water upon reaching settling tank T-3. Figure 2-1 shows the location of the PCS scavenger wells, extraction points and extraction wells.

CDS Groundwater Treatment System

The 1992 groundwater treatment system was designed to meet effluent requirements by removing a variety of VOCs and suspended metals and sediment. It was modified in December 1998 to treat flows from the new extraction wells added to the PCS and again in 2001 to treat flows from the RDS Groundwater IRM recovery system (Figure 2-3). SCS groundwater is filtered, pumped through granular activated carbon (GAC) to remove VOCs, and then passed through the UV/Oxidation system and bag filters to remove paradioxane and suspended solids. The PCS groundwater is pumped to settling tank T-3, filtered, and finally processed by adsorption by GAC. The CDS groundwater treatment system as currently designed can process up to approximately 178 gallons per minute. Effluent from the treatment system meets New York State Class GA groundwater guidelines and is discharged to an intermittent stream in accordance with NYSDEC effluent discharge requirements. The stream discharges to a one-acre pond (CDS Outfall Pond), which discharges to Cayuga Lake over a three-mile course of culverts and open channel flow.

3. Site Activities in 2020

3.1 Operation, Maintenance, and Monitoring of Final Remedial Measures

Site activities during 2020 included:

• Inspections, testing, and monitoring to fulfill requirements of site-related permits;
• Operation and maintenance of the groundwater recovery and treatment systems;
• Performance monitoring of the treatment plant;
• Performance monitoring of the groundwater recovery systems;
• Inspection and maintenance of source area containment systems;
• Performance monitoring of the source area containment systems;
• Environmental monitoring of contaminant concentrations and distribution near the sites.

3.2 Reports Submitted to the NYSDEC

• Annual Report for 2019 for the CDS and RDS (March 2020).
• Discharge Monitoring Reports for the Groundwater Treatment Plant submitted monthly.
• Part 380 Discharge Reports for the Groundwater Treatment Plant submitted quarterly.

• In addition, Cornell University prepared and submitted a work plan for low-level (0.35 µg/L detection limit) 1,4-dioxane sampling and analysis at select locations in 2020, as requested by NYSDEC. 

3.3 NYSDEC Approvals and Permits Issued

None.

3.4 Public Participation

Since the RODs have been fully implemented at both the CDS and the RDS, ongoing public participation activities are minimal. Site information including this report is available on the internet at the RDS and CDS Sites website.

3.5 NYSDEC Inspections

Personnel from NYSDEC’s Radiological Sites Section completed inspections of the groundwater treatment plant and RDS in October 2020.

4. Monitoring Overview

4.1 Sample Collection and Analysis

Summaries of sampling and monitoring activities conducted in 2020 at the RDS, CDS and GWTP are included in Table 4-1. Sampling activities at the RDS followed Table 4-1of the Site Management Plan (December 2007, revised September 2014) for 2020. Monitoring wells RDS-12WS, RDS-19X, RDS-25X and P-4 were removed from the schedule, as proposed and communicated to NYSDEC in 2018. Field data collected during sampling activities is on file at Cornell and is not included in this Annual Report.

Sampling activities in 2020 at the CDS were performed in accordance with Table 4-1 of the Site Management Plan.

Sampling activities at the GWTP were completed as shown on Table 4-1 in accordance with the Substantive SPDES and Part 380 permits for the GWTP and Table 4-2 of the Site Management Plan.

Monitoring activities associated with the RDS Remedial Measures are summarized on Table 4-1. These activities were performed in accordance with Table 4-1 of the Site Management Plan.

Groundwater sampling locations for both the CDS and RDS are shown on Figure 2-1. Quarterly samples are taken in March, June, September, and December. Additional semiannual samples are taken in March and September, and additional annual samples are taken in September. Surface water sampling locations for the CDS are shown on Figure 2-1.

The water quality monitoring program for the RDS focuses on testing for paradioxane (the primary site contaminant), tritium, carbon-14 and strontium-90. The water quality monitoring program for the CDS focuses on testing for volatile organic compounds (the primary site contaminants). The monitoring program for the GWTP focuses on testing discharge from the plant to ensure compliance with the substantive SPDES permit.

In addition to water sampling, monitoring of the Remedial Measures at both sites was performed in 2020 in accordance with the approved O&M Plans or Performance Monitoring Manuals for these measures.

Source Area and PCS monitoring for the CDS was performed in accordance with the Site Management  Plan. Operations at extraction well EP-2 (PCS-Shallow) and EW-3 (PCS-Deep) were discontinued as planned.  Analytical data at these wells indicate only low levels of contaminants below the AWQS remain.

Cornell University personnel performed all the water sampling and routine operation and maintenance activities.

Analytical services were provided by Eurofins Testing Northeast, Inc. and GEL Laboratories.

4.2 RDS Groundwater and Surface Water Monitoring

Routine sampling of groundwater and surface water at the RDS is summarized on Table 4-1. All samples were collected as planned with the exception of surface water samples.  Surface water sampling locations SW-7, SW-7E, and SW-37 were dry in June, and Septembera nd snow covered in December.

Additional surface water samples were also collected from SW-6 in June and December and additional groundwater samples were collected for low-level 1,4-dioxane analysis .
 

4.3 CDS Groundwater and Surface Water Monitoring

Routine sampling of groundwater and surface water at the CDS is summarized on Table 4-1. All samples were collected as planned.

Additional groundwater samples were collected for low-level 1,4-dioxane analysis.

4.4 Monitoring of Remedial Measures

Routine site monitoring for the CDS and RDS Remedial Measures (CDS PCS-Deep, RDS Groundwater Recovery System, and RDS Cap) is summarized on Table 4-1.

4.5 Groundwater Treatment Plant Monitoring

Routine Groundwater Treatment Plant monitoring is summarized on Table 4-1. All samples were collected as planned. Sampling and analysis of the RDS influent for Carbon-14,Strontium-90 and Tritium was conducted in accordance with the bag filter management plan required under the substantive Part 380 discharge permit.

An additional effluent sample was collected for low-level 1,4-dioxane analysis.

5. Geologic, Hydrologic, and Climatological Setting

5.1 2020 Climate Summary

Precipitation for the year was 36.81 inches, which is 99% of normal (0.49 inches below average). The average temperature in 2020 was 48.08°F, 1.48°F above normal. Additional climatological data can be found at: Northeast Regional Climate Center.

5.2 Geology and Hydrology

The CDS and RDS are underlain by approximately 10 to15 feet of glacial till and 20 to25 feet of shallow highly fractured predominantly shale bedrock that transitions to more competent bedrock at a depth of about 40 feet below ground surface. Groundwater is present in all three zones, with the fractured shale being the predominant flow zone. The general direction of groundwater flow is southwesterly in the till, southwesterly in the fractured shale bedrock, and westerly in the competent bedrock.

Surface water flows from northeast to southwest across the CDS and RDS, often following drainage pathways such as culverts and ditches. Two intermittent streams flow southwest from the vicinity of the sites and eventually combine to form the south branch of Twin Glens Creek. Twin Glens Creek flows into Cayuga Lake approximately three miles west of the sites.

5.3 Hydrogeology

Groundwater elevation data were collected approximately quarterly from till, fractured shale, and bedrock wells at both the RDS and CDS. The complete set of raw water level elevation data from 2020 is on file at Cornell and has not been included in this report.

The direction of groundwater flow in this zone is generally toward the southwest. Even though groundwater elevations in 2020 varied with the season, the direction of flow remained consistent with previous observations.

6. RDS Monitoring Results

Discussed below are the 2020 monitoring results related to groundwater quality. Included as Appendices are historical summaries of groundwater analytical results for paradioxane, tritium and strontium-90 (Appendix B); and historical summaries of surface water analytical results for paradioxane (Appendix C).

6.1 Groundwater Monitoring

Groundwater monitoring focuses on the fractured shale unit because past monitoring has shown this is the primary zone of contaminant migration.

6.1.1 Laboratory Analysis

Table 6-1 summarizes the paradioxane analytical results from groundwater samples collected in 2020.

6.1.1.1 Paradioxane

• Areal Extent of Plume in Fractured Shale – The extent of areas where concentrations of paradioxane were greater than 50 μg/L (the remedial cleanup standard) in till/fractured shale wells at the time of the annual sampling event in September is depicted on Figure 6-2. See discussion regarding the RDS pumping system operation in Section 8.1.
• Temporal Variations – Temporal variations in concentrations of paradioxane in representative wells upgradient, near and downgradient of the Groundwater Recovery System are shown on Table 6-1. Concentrations of paradioxane detected in 2020 are, on average, lower than the concentrations detected in these wells prior to completion of the RDS source area containment in 2003, as shown below:

• Paradioxane Concentration in Selected Wells (μg/L)

  Well	Location	2000 - 2002 Average	2020 Average	% Reduction
  RDS-10WS	Between disposal area and RDS recovery wells	555	76	86%
  RDS-9WS	Near RDS recovery wells	131	ND	100%
  RDS-11WS	Downgradient of recovery wells	105	48	54%
  RDS-13WS	Downgradient of recovery wells	214	ND	100%

  Exceedances of Groundwater Quality Standards – Table 6-1 summarizes water quality exceedances in 2020. Concentrations of paradioxane exceeded 50 μg/l during one or more sampling events in 8 of the 12 wells sampled, 7 north of Snyder Road and 1 south of Snyder Road (RDS-11WS).

6.1.1.2 Radionuclides

Table 6-2 summarizes the radionuclide analytical results from groundwater samples collected in 2020.

• Temporal Variations – Average concentrations of tritium, strontium-90 and carbon-14 detected in 2020 were generally lower than those detected prior to completion of the RDS source area containment in 2003.
• Exceedances of Groundwater Quality Standards – NYSDEC has not set Ambient Water Quality Standards for radionuclides in groundwater.

6.1.2 Conclusions

Average paradioxane concentrations in groundwater in 2020 were generally below the average concentrations observed prior to installation of remedial measures in 2003 and 2004. Continued pumping and treatment of RDS groundwater is planned for 2021 (see discussion below). The performance of the remedial measures is discussed in detail in section 8 below.

6.2 Surface Water

Surface water samples were collected from four (4) RDS surface water locations and submitted for paradioxane analysis in 2020. Paradioxane was not detected. See Table 6.1.

6.3 Recommendations for 2021

Groundwater and surface water monitoring will continue in 2021 in accordance with the Site Management Plan.  In addition, sampling for low-level 1,4-dioxane will continue as requested by NYSDEC.

7. CDS Monitoring Results

7.1 Groundwater Monitoring

Groundwater monitoring focuses on the fractured shale unit because past monitoring has shown this is the primary zone of contaminant migration.

7.1.1 Chemical Analysis

The groundwater sampling schedule followed for 2020 is summarized in Table 4-1. 2020 VOC concentrations in monitoring wells, piezometers and extraction wells are included in Table 7-1. Recent historical groundwater sampling results, including results from 2020, are included in Appendix E.

• Areal Extent of Plume in Fractured Shale: Figure 7-1 depicts the approximate extent of the contaminant plume from the CDS, as derived from the concentration of total VOCs in the fractured shale monitoring wells in September (See Table 7-1). Paradioxane is not included in the total VOCs summarized in Table 7-1 or on Figure 7-1. The highest concentrations of total VOCs were found in monitoring wells MW-22D,MW-30D, and 9D.
• Temporal Variations – As in previous years, VOC concentrations exhibited a seasonal variation.
• Most Frequently Detected Contaminants: Trichloroethylene (TCE) remained the compound detected most frequently and in the highest concentrations in monitoring wells in 2020. Other compounds frequently detected in monitoring wells and piezometers in 2020 included 1,2-dichloroethane, cis-1,2-dichloroethylene, 1,2-dichloropropane and chloroform, similar to previous years (Appendix E).
• Exceedances of Groundwater Quality Standards: One or more volatile organic compounds were detected in concentrations exceeding water quality standards or guidance values in 6 monitoring or extraction wells in 2020 (Table 7-1). Compounds detected in concentrations above water quality standards or guidance values included 1,2-dichloroethane, cis-1,2-dichloroethylene and trichloroethylene.

7.1.2 Conclusions

Peak VOC concentrations in the center of the CDS plume were similar to those seen during 2019 and remained lower than the typical values seen during the several years prior to completion of the CDS remedial actions. The plume remained similar in terms of location and areal extent.

7.2 Surface Water

7.2.1 Chemical Analysis

Surface water samples are collected semi-annually from the drainage ditch north of the Airport runway (SW-41). Results are summarized in Table 7-3. Trichloroethene was detected at SW-41 at a concentration below NYSDEC standards and guidance values. Toluene was also detected. Historical surface water sampling results are included in Appendix F.

7.2.2 Conclusions

Surface water sampling at SW-41 indicate the presence of low levels of Trichloroethene, and Toluene at concentrations below NYSDEC standards and guidance values.

7.3 Recommendations for 2021

Groundwater and surface water sampling will continue in 2021 in accordance with the Site Management Plan.  Conduct additional sampling for low-level 1,4-dioxane analyses, as required by NYSDEC.

8. Remedial Measures

8.1 RDS Source Control System

The Final Remedy for the RDS source area was installed during 2003 and 2004. The source area containment measures consist of a grout curtain in the bedrock, a soilbentonite wall in the soil layer, and a multi-layered capping system. The grout curtain and soil-bentonite wall are together referred to as the barrier wall. Monitoring of these measures was performed in 2020 in accordance with the Site Management Plan (Cornell University, October 2014).

8.1.1 Water Testing Results

Seven monitoring wells surrounding the RDS barrier wall were tested quarterly for paradioxane. Four of these seven wells were also tested annually for tritium, carbon-14 and strontium-90. These analytical results are summarized in tables 6-1 and 6-2.

Paradioxane is the primary chemical tracer for evaluating the effectiveness of the RDS barrier wall in containing the source area contaminants. The table below presents a summary of the paradioxane data for 2020 compared to the three years before the barrier wall was installed.

As shown on the table above, paradioxane concentrations have significantly decreased along the south and west sides of the disposal area since the installation of the barrier wall. Average paradioxane results along the east side are similar to those observed in 2019.

Strontium-90, Tritium and Carbon-14 were detected in one or more wells (Table 6-2).  However, these results are typically lower than results from previous years (Appendix B).

8.1.2 Operation, Repair, and Maintenance

Maintenance and repair activities at the CDS and RDS, including the RDS Source Control System, for 2020 were similar to 2019. Cap inspections were conducted quarterly during 2020. The cap was observed to be in generally good condition with good vegetative cover and no significant areas of erosion or poor drainage. Cornell performed routine maintenance for the RDS including soil placement and seeding at monitoring well areas; mowing of cap, side banks and security fenceline; repairs to the site fencing; proactive tree work; rodent controls; and drainage system improvements as needed.

8.1.3 Conclusions

The RDS source control system remained in-place. While paradioxane concentrations in groundwater have decreased on the west side of the disposal area, the decrease has not been as significant on the east side of the disposal area. It remains unclear whether this is related to migration of residual contamination located outside the barrier wall or is indicative of transport around or through a portion of the barrier.

8.1.4 Future Plans for Source Control

Operation, maintenance, and monitoring will continue in accordance with the Site Management Plan.

8.2 RDS Groundwater Recovery System

8.2.1 Chemical Evaluation

Influent from the RDS Groundwater Recovery System was sampled and analyzed for paradioxane on a monthly basis in 2020. Results are provided in Table 8-2. The range of paradioxane in the influent varied from 44 (J) ug/L in September to 128 μg/L in December.

In addition, samples were collected from the active RDS extraction well (RW-111) quarterly in 2020. Results are provided in Table 6-1. Paradioxane concentrations in the pumping well varied from 63.1 μg/L in September to 124 μg/L in March.

8.2.2 Conveyance Line Inspections

Conveyance line inspections were conducted quarterly. Infiltration of surface water into the tie-in manhole and inspection sumps occurred occasionally during 2020; dewatering was required following especially heavy rain or snow melt.

8.2.3 Operation, Repair and Maintenance

Cornell University continued to operate RW-111 throughout 2020.

Maintenance and repair activities related to the recovery system included repair of cover drains, placement of fabric and stone, mowing and pumping of infiltrated surface water from the tie-in manhole and conveyance line inspection sumps.

8.2.4 Recommendations and Future Plans

Monitoring of the groundwater plume at strategic locations north and south of Snyder Road will continue during 2021 in accordance with the Site Management Plan to document the effectiveness of the barrier system and the groundwater recovery system.

Cornell University will continue pumping operations from recovery well RW-111 in 2021. Groundwater monitoring data will be evaluated to assess whether modifications to the pumping strategy may be warranted. Cornell University will operate the groundwater recovery system until the paradioxane concentration in groundwater monitoring wells south of Snyder Road (RDS-11WS and RDS-13WS) remains below 50 μg/L for four (4) consecutive quarters.

Cornell University will utilize a contract driller in 2021 to re-develop RW-111 and MW-11WS using physical and chemical processes.

8.3 CDS Source Control System

8.3.1 Hydraulic Evaluation

The hydraulic head differential across the groundwater barrier wall was measured using four pairs of wells (couplets), each consisting of a piezometer located within the area enclosed by the groundwater barrier wall and a monitoring well located just outside the groundwater barrier wall (Figure 2-2). Groundwater levels were obtained from these piezometer couplets weekly.

The on/off level set points of the pumping wells inside the source area are designed to maintain an inward hydraulic head differential (i.e., a hydraulic flow potential of groundwater from outside the groundwater barrier wall to inside the groundwater barrier wall). Operating guidelines call for maintaining a minimum inward head differential of one foot, which minimizes the potential for releases of contaminants underneath or through the groundwater barrier wall.

Table 8-1 reports the range in head differentials. A head differential of at least one foot was maintained along all sides of the CDS throughout 2020.

In addition to creating an influence on the horizontal hydraulic flow potentials, the SCS affects the vertical hydraulic flow potential. Pumping from the extraction wells creates a vertical hydraulic head potential in the upward direction. This minimizes the potential for downward migration of dissolved contaminants beneath the CDS.

8.3.2 Chemical Analysis

8.3.2.1 Volatile Organic Compounds in System Influent

Grab samples analyzed for VOCs were collected monthly from the SCS groundwater influent to the treatment plant. VOC influent results are presented in Table 8-2. Benzene, 1,2-Dichloroethene, 1,2-Dichloroethane (DCA), 1-4, Dioxane, and trichloroethylene (TCE) were present at the highest concentrations.  Concentrations of VOCs observed in the influent from the SCS were generally consistent with what has historically been observed.

8.3.2.2 Volatile Organic Compounds in Groundwater

Concentrations of VOCs in monitoring wells adjacent to the CDS source area (monitoring wells MW-8 through MW-12, Table 7-1) remained consistent with recent monitoring during 2020, yielding no evidence of significant leakage of groundwater from inside the CDS.

8.3.3 Conclusions

The CDS source control system was effective during 2020 in preventing discharges or exposures from site-related contaminants. An inward hydraulic gradient across the barrier wall was maintained throughout the year.

8.3.4 Recommendations and Future Plans

Operation, maintenance, and monitoring will continue in accordance with the Site Management Plan.

8.4 CDS Plume Collection System

The Plume Collection System includes two groundwater collection systems:

1. A shallow system consisting of three scavenger wells and a collection trench in the glacial till deposits and upper few feet of bedrock (known as the PCS-Shallow recovery system), and
2. A deeper system consisting of seven extraction wells capturing groundwater flow in the fractured shale deposits 10 to 40 feet below ground surface (known as the PCS-Deep recovery system).

Portions of the Trench Upgrade (PCS-Deep) Performance Monitoring sampling were continued in 2020, including collection of samples from selected wells for VOC analysis.  Operation of the PCS-Shallow system and extraction well EW-3 were discontinued in 2020 after monitoring data showed contamination levels were consistently below NYSDEC's ambient water quality standards.

8.4.1 Hydraulic Evaluation

Water level measurements provide the primary means for verifying that the PCS is working properly. The potentiometric surface contours indicate that the groundwater flow potential from the CDS is toward the southwest, and that the plume collection system is maintaining hydraulic control in the fractured shale unit.

Sampling of the individual PCS-Deep extraction wells over a period of several years indicated minimal levels of contaminants were present at the ends of the extraction well alignment (i.e. EW-1, EW-2, EW-6 and EW-7). Similarly, EW-3 operations were discontinued in March 2020.  In order to focus the groundwater extraction process on the zone of contaminant migration, only wells EW-4 and EW-5 were operated during continuously during 2020.

8.4.2 Chemical Analysis

8.4.2.1 Volatile Organic Compounds

The concentrations of VOCs in monthly grab samples of the influent from the PCS-Deep recovery system are summarized in Table 8-2. Compounds detected and the ranges of concentrations were similar to previous years. The average concentrations of the total VOCs detected in the PCS-Deep influent streams were similar to 2019 (Appendix G).

In addition to the samples from the PCS-Deep influent streams, an annual sample was taken from each of the operating PCS-Deep extraction wells (EW-3 through EW-5). The results are summarized on Table 7-1. The highest concentration of total VOCs in the plume collection system extraction wells was detected in a sample from EW-4 (30 μg/L). This well is in the center of the plume collection system. VOCs detected in samples from the extraction points in 2020 were similar to previous years (Appendix E).

PCS-Deep recovery system monitoring included quarterly sampling of monitoring wells MW-27D, MW-30D, MW-33D and MW-35D. Concentrations of volatile organic compounds over time in wells MW-30D (center of plume), MW-35D (within the PCS well alignment), and MW-33D (downgradient of PCS), are plotted on Figure 7-2. The large variations in VOC concentrations at well MW-30D (center of plume) seen on the chart are the result of seasonal factors affecting groundwater flow and recharge.

8.4.3 Operation, Repair and Maintenance

Maintenance and repair activities at the Plume Collection System for 2020 were similar to 2019.

8.4.4 Conclusions

The PCS maintained consistent hydraulic control of the groundwater plume on the airport property during 2020. Concentrations of VOCs at down gradient well MW-33D and surface water location SW-41 were within the range typically seen since monitoring began at these locations in 1998 (Appendix F).

8.4.5 Recommendations and Future Plans

Monitoring of the Plume Control System will continue in 2021 in accordance with the Site Management Plan. Hydraulic and water quality conditions near the collection trench will continue to be evaluated, and the active PCS-Deep recovery system extraction wells (EW-4 and EW-5) will continue to be monitored to ensure prompt resolution of any problems with the operation of the groundwater pumps and associated equipment.

Cornell University has also developed and submitted a work plan to NYSDEC to pulse the PCS-D system.  This pulsing effort is intended to determine whether the PCS-D system has reached asymptotic conditions and to evaluate whether a transition to monitored natural attenuation is warranted.

8.5 Groundwater Treatment Plant

8.5.1 Flow Evaluation

The Groundwater Treatment Plant processed over 2 million gallons of groundwater from the CDS and RDS during 2020 (Table 8-3).

8.5.2 Laboratory Analysis

8.5.2.1 Volatile Organic Compounds and Paradioxane

As reported in the Discharge Monitoring Reports submitted monthly to the NYSDEC, all final effluent volatile organic chemical concentrations were within the effluent requirements (Table 8-4).

8.5.2.2 Metals

Quarterly samples from the Groundwater Treatment Plant are analyzed for 18 metals, while monthly samples are analyzed for 6 of these metals. All effluent metal concentrations were below their respective effluent discharge limitations with the exception of manganese in March (Table 8-5).

8.5.2.3 Radionuclides

The substantive Part 380 Radiation Control permit requires the submission of annual activity report that includes the number of days the treatment plant operated, the total volume of water discharged, and the total RDS-related activity (Appendix D).

8.5.3 Hazardous Waste Generated

Spent bag filter and carbon waste was generated in 2020.  Ten drums of spent carbon waste were shipped offsite for reactivation and returned in 2020.

8.5.4 Repair and Maintenance

Maintenance and repair activities at the CDS and RDS, including the Groundwater Treatment Plant, for 2020 were similar to 2019. Maintenance and repair activities related to the Groundwater Treatment Plant included response to system alarms.

Routine activities included items such as scheduled feed pump, peroxide pump, unit heater, GAC vessel, treatment system and compressor maintenance and repairs; ball valve/ball check replacement; activated carbon placement, painting and cleaning, hydrogen peroxide, potable water and propane delivery, ridge vents properly infilled and insulated, light fixture lamp replacement (LEDs), pH probe sensor cleaning/calibration/replacement, pump controls desiccant replacement, changing of bag filters and exterior building/lighting improvements.

8.5.5 Conclusions

The Groundwater Treatment Plant was operational throughout 2020 and treated over 2 million gallons of water.

8.5.6 Recommendations

Monitoring and maintenance activities at the Groundwater Treatment Plant will continue in 2020 in accordance with the Site Management Plan.  In addition, sampling for low-level 1,4-dioxane analyses will continue, as requested by NYSDEC.

8.6 Summary of Operations, Recommendations for 2021, and Future Plans

The RDS Source Area containment has minimized infiltration and prevented release of VOCs and radionuclides from the disposal site via air or surface water. Cornell will continue to monitor and evaluate the paradioxane concentrations near the disposal area to determine if any changes in the Site Management Plan are warranted. The RDS Groundwater Recovery System continued to control and treat the paradioxane groundwater plume near Snyder Road.

The CDS Source Control System is working as designed, preventing migration of contaminants from the site via groundwater by maintaining hydraulic control within the disposal area. The cap has been effective at preventing direct contact with waste and reducing infiltration into the waste. The CDS Plume Collection System operated as designed and maintained hydraulic control throughout the year. Operation, maintenance and monitoring of the CDS and RDS remedial measures will continue in 2021.

Plans for 2021 include continued performance monitoring of the remedial measures in accordance with the Site Management Plan. In addition, groundwater monitoring wells and other infrastructure no longer in use may be decommissioned.

9. References

Cornell University, 2001, Revised Application for 6 NYCRR Subpart 380-3 Limitations
        for Radiological Discharge to Surface Water

Cornell University, 2001, Bag Filter Management Plan, Cornell University Radiation
       Disposal Site, Lansing, New York.

Cornell University, 2003, Chemical Disposal Site Cover and Cap Remedial Design
       Report.

Cornell University, 2004, Radiation Disposal Site Final Remedy Final Engineering
       Report.

Cornell University, 2014, Site Management Plan.

Cornell University, 2020, Chemical Disposal Site and Radiation Disposal Site 2019
       Annual Report.

D. A. Collins, 2004, Cornell University CDS Cap and Cover O&M Manual.

McLaren/Hart, Inc. 1997. Remedial Investigation Report, Cornell University Radiation
       Disposal Site.

McLaren/Hart, Inc. 1997. RDS Monitoring Plan, Cornell University Radiation Disposal
       Site.

McLaren/Hart, Inc. 1999. Baseline Human Health Risk Assessment, Cornell University
       Radiation Disposal Site.

McLaren/Hart, Inc. 1999. Supplemental Remedial Investigation Report, Cornell
       University Radiation Disposal Site.

McLaren/Hart, Inc. 1998. Interim Remedial Measure Final Engineering Report,   
       Appendix N, Operations and Maintenance Manual for the Cornell University
       Radiation Disposal Site.

McLaren/Hart, Inc. 1999. Feasibility Study for the Cornell University Radiation Disposal
       Site.

New York State Department of Environmental Conservation. 1996. Order on Consent,
       Index # A7-0333-95-08.

New York State Department of Environmental Conservation. 1998. Ambient Water
       Quality Standards and Guidance Values and Groundwater Effluent Limitations.

New York State Department of Environmental Conservation, 2002, Record of Decision,
       Cornell University, Radiation Disposal Site, Lansing, Tompkins County, Site 7-55-001.

New York State Department of Environmental Conservation, 2003, Substantive Part 380
       Permit #7-5032-00102100001.

New York State Department of Environmental Conservation, 2002, Substantive SPDES
       Permit #7-55-002.

New York State Department of Environmental Conservation. 1993. Part 382 Regulation
       of Low-level Radioactive Waste Disposal Facilities: Certification of Proposed
       Sites and Disposal Methods

Sovereign Consulting Inc., 2001, Performance Monitoring Plan, Cornell University
       RDS/CDS Groundwater Treatment Plant, Lansing, New York.

Sovereign Consulting Inc., 2002, Final Engineering Report-Groundwater Interim   
       Remedial Measure & Groundwater Treatment Plant Modifications & Upgrades.

Sovereign Consulting Inc., 2002, Final Remedy Design Report and 6 NYCRR Part 380
       Performance Assessment.

Sovereign Consulting Inc., 2002, RDS Source Area Pre-Design Subsurface Investigation
       Data Report.

Tables

2020 RDS and CDS Annual Report Tables

All Tables

4-1 2020 RDS Sampling and Monitoring Schedule
6-1 2020 Paradioxane Concentrations in RDS Monitoring Wells
6-2 2020 Radionuclide Concentrations in RDS Monitoring Wells
7-1 2020 VOC Concentrations in CDS Piezometers, Monitoring and Extraction Wells
7-2 2020 VOC Concentrations in CDS Surface Water
8-1 CDS Source Control System 2020 Piezometer Differentials
8-2 Treatment Plant Influent & Process Samples 2020 VOC Concentrations
8-3 Treatment Plant Effluent 2020 Flow Data
8-4 Treatment Plant Effluent 2020 VOC Concentrations
8-5 Treatment Plant Effluent 2020 Metals Concentrations
 

Figures

2020 RDS and CDS Annual Report Figures

Figures PDF

1-1 Site Location Map

2-1 RDS and CDS Site Map
2-2 CDS Disposal Area Map
2-3 Process Flow Diagram CDS/RDS Groundwater Treatment Plant
6-1 Paradioxane Concentrations in Wells near Groundwater IRM
6-2 Concentration of Paradioxane in Groundwater, RDS Fractured Shale Bedrock – September 2020
7-1 Concentration of VOCs in CDS Fractured Shale Wells, September 2020
7-2 VOC Concentrations in Wells Near Plume Control System

Appendices

2020 RDS and CDS Annual Report Appendices

Appendices PDF

1. RDS Quarterly Inspection Notes
2. RDS Historical Groundwater Quality Data
3. RDS Historical Surface Water Quality Data
4. RDS Annual Activity Summary
5. Historical CDS Groundwater Quality Data
6. Historical CDS Surface Water Quality Data
7. Historical Groundwater Treatment Plant Influent Data
8. IC/EC Certifications