Keystone Sanitation Landfill
SUPERFUND PROGRAM PROPOSED PLAN
TO AMEND THE OPERABLE UNIT ONE
RECORD OF DECISION
Keystone Sanitation Landfill
Union Township, Adams County, Pennsylvania
EPA ANNOUNCES PROPOSED PLAN - June 1, 2000
Dates to remember:
June 5, 2000 to July 5, 2000
Public Comment Period for Proposed Plan
June 22, 2000, 7:00 pm
Public meeting at Abbottstown Fire Company
The United States Environmental Protection Agency (EPA) has completed a Focused Feasibility Study (FFS) of an Alternative Source Control Remedy for the Keystone Sanitation Landfill, located in Union Township, Adams County, Pennsylvania. The landfill and any surrounding areas that have been contaminated by the landfill are part of the Keystone Sanitation Landfill Superfund Site (Site). The FFS considers the use of an Alternate Source Control Remedy which uses an Enhanced Landfill Gas Extraction (ELGE) system to remove and destroy Volatile Organic Compounds (VOCs) from the landfill. If approved, this ELGE system would be used instead of a landfill cap to prevent VOCs from entering into the groundwater.
Based on the results of an ELGE pilot test conducted at the Site and the associated FFS, EPA is proposing the following modifications to the Operable Unit One (OU-1) Record of Decision (ROD) dated September 30, 1990: to capture, contain and clean up VOCs from the landfill by installing landfill gas extraction wells within the landfill; and to improve the existing landfill cover by increasing the depth of the soil cover to a minimum of 2 feet across the landfill. This Proposed Plan summarizes the findings of the FFS report, provides details on EPAs preferred remedy summarized above, and explains the reasons for this preference. In addition, the Proposed Plan explains how the public can participate in the decision-making process and provides names, addresses, and telephone numbers for the appropriate EPA contacts. Terms highlighted in the Proposed Plan in bold italic print are defined in a glossary of relevant technical and regulatory terms provided at the end of this Proposed Plan.
EPA is the lead agency for Superfund activities at the Site. EPA will select a final remedy for the above-described components of the ROD after the public comment period has ended and all the comments have been reviewed and carefully considered. EPA may select a modified version of the preferred alternative, based on new information or public comments. The amended ROD will be placed in the administrative record for the Site.
EPA is issuing this Proposed Plan as part of its public participation responsibilities under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Sections 113(k) and 117(a). EPA encourages the public to review this Proposed Plan, the FFS and the other supporting documents included in the administrative record for the Site. The administrative record is available in the following locations:
Hanover Public Library
Hanover, PA 17331
U.S. EPA, Region 3
Administrative Records Room
1650 Arch Street
Philadelphia, PA 19103
Contact: Anna Butch
Call for appointment: (215) 814-3157
Comments on this Proposed Plan should be postmarked no later than July 5, 2000 and sent to:
Ms. Kelley A. Chase (3HS21)
U.S. Environmental Protection Agency
1650 Arch Street
Philadelphia, PA 19103-2029
Oral or written comments can also be given to EPA at the public meeting scheduled for 7:00 pm, Thursday June 22, 2000 at the Abbottstown Fire Company Hall, 138 East King Street, Abbottstown, PA.
SCOPE AND ROLE OF RESPONSE ACTION
This is the third Proposed Plan issued by EPA for the Site. The first Proposed Plan was issued on July 20, 1990 to address contamination of all media (i.e., soil, groundwater, surface water, sediments) affected by the Site. Based on public comment, in the September 30, 1990 ROD, EPA determined that it would address contamination from the Site by dividing EPAs response activities into two operable units. The remedy selected in the 1990 ROD required, among other things, placement of an impermeable cap on the landfill, construction of a groundwater extraction and treatment system and monitoring of residential wells, surface water and sediments. The purpose of the groundwater extraction system was to prevent contaminated groundwater originating under the landfill from migrating to areas outside the landfill boundaries and to reduce groundwater contamination to established cleanup goals. The ROD also required additional study of contamination outside the boundaries of the landfill, the subject of the second Proposed Plan. These studies were labeled Operable Unit Two (OU-2) to distinguish them from the previous studies. However, EPA later decided to address the Site as one operable unit, OU-1. On June 25, 1999, EPA amended the OU-1 ROD to address groundwater contamination outside the boundary of the landfill.
This Proposed Plan calls for an Alternative Source Control Remedy which employs an ELGE system to remove and destroy VOCs and methane from the landfill rather than the impermeable cap which was selected in the 1990 ROD. In addition to the installation of the ELGE system, the proposed Alternate Source Control Remedy includes: upgrades to the existing soil cover; monitoring to ensure proper functioning of the ELGE system and to measure VOC removal from the landfill; monitoring of the leachate to ensure that the landfill is not a continued source of VOC contamination to the groundwater; use of surface water management controls to minimize soil erosion and sedimentation; maintenance of the existing fence; and deed restrictions on the use of the property.
The response actions for the groundwater selected in September 1990, as amended in June 1999 remain unchanged. The remedial response actions discussed in this Proposed Plan, in conjunction with response actions for the groundwater contamination, will comprehensively address the threats posed by the release or potential release of hazardous substances from this Site.
The Site is an inactive, privately owned facility that operated from 1966 to April 1990 and was permitted by the Pennsylvania Department of Environmental Resources (PADER), the predecessor to the Pennsylvania Department of Environmental Protection (PADEP). The landfill was permitted to receive household and municipal wastes and certain types of industrial and construction debris. The landfill is located on a 40-acre tract in Union Township, Adams County, Pennsylvania, southwest of Hanover, Pennsylvania. See Figure 1. The landfill property is bordered to the south by Line Road, to the north by Clouser Road, and is approximately 800 feet north of the Pennsylvania-Maryland border. The entire landfill property has been fenced, in accordance with requirements of the 1990 ROD.
The landfill was constructed without a liner or leachate collection system. Wastes were deposited to a depth of approximately 30 feet. Bedrock beneath the Site has been mapped as the Marburg Schist. Overlying the fractured bedrock are varying thicknesses of silty clay soil that was used to construct the base and for daily, intermediate, and final cover. The landfill has a maximum elevation of approximately 780 feet and a vertical relief of approximately 200 feet within 2,000 feet of the Site. Perennial grass covers the Site.
The landfill is situated on top of a ridge. The topography of the area consists of gently rolling hills and valleys formed by elongated, northeast-trending ridges and valleys. Numerous small springs within the vicinity of the Site discharge to surface water bodies.
The Site is located in a rural residential/agricultural area. Groundwater is the only source of potable water in the area and residents near the Site are dependent on private wells. During the 1997 OU-2 RI, it was estimated that there were approximately 75 residences within one-mile of the Site. This number is increasing due to residential development in the vicinity of the Site.
In 1982, in accordance with State permitting requirements, groundwater monitoring for VOCs was conducted. VOC contamination was detected in on-site monitoring wells and in a nearby spring, Mundorff Spring, which is located east of the Site.
In April 1984, an EPA Field Investigation Team performed a site investigation in response to citizens complaints of groundwater contamination in residential wells. Sampling results from PADER and EPA confirmed the presence of low levels of VOC contamination in some of the residential wells.
In August 1984, the owners of the landfill installed a spray irrigation system in the most contaminated groundwater area to prevent the migration of contaminants off-site and to remove VOC from the groundwater. Spray irrigation is a practice consisting of spraying contaminated groundwater on a field and allowing VOCs to evaporate into the air. The spray irrigation system was operated until 1992. In addition, leachate collection was attempted on the southern side of the landfill along Line Road. Two perforated pipes were located at the base of the landfill. The pipe ran parallel to Line Road and discharged into a storage tank. The storage tank was pumped periodically, and the contents were disposed off-site.
In the spring 1985, the State of Maryland installed monitoring wells at the Maryland border to monitor potential contaminant migration. Low levels of VOC contamination have been consistently detected in at least one of these wells.
The Keystone Sanitation Landfill Site was placed on the Superfund National Priorities List (NPL) in July 1987. This list includes sites where uncontrolled hazardous substance releases present the most significant potential threats to human health and the environment.
In 1987, EPA began a Remedial Investigation (RI) and Feasibility Study (FS) at the Site. The RI field activities began in the spring of 1989. The RI/FS reports were issued in July 1990 and finalized in September 1990. EPA issued the OU-1 ROD on September 30, 1990. The remedy selected in the OU-1 ROD included:
- Installation and maintenance of an impermeable cap and gas collection system over the 40-acre landfill;
- Installation and maintenance of on-site groundwater extraction wells and a treatment plant to capture, contain and reduce the concentrations of VOCs and metals in groundwater;
- Provision of a point-of-use groundwater treatment system to on-site residents;
- Installation and maintenance of a fence around the Site;
- Monitoring of the groundwater in monitoring and residential wells;
- Monitoring of surface water and sediments;
- Initiation of deed restrictions regarding present and future activities on the landfill property.
To date, the fence and the on-site point-of-use groundwater treatment system have been completed. Construction of the extraction wells and groundwater treatment plant has recently been completed. EPA expects the plant will begin operating later this summer.
In addition, the ROD included a requirement to perform another RI to further study the groundwater contamination in the off-site residential wells and off-site monitoring wells. This RI was completed in January 1998 During the second investigation, EPA collected groundwater samples from 72 monitoring wells, sampled 74 residential wells, and sampled surface water and sediment at numerous locations. Based on the results of the second RI, the ROD was amended on June 25, 1999 to address groundwater contamination outside the boundaries of the landfill. As required by the June 1999 Amendment, carbon filtration units have been offered to residents within 3/4 miles of the landfill. To date, the majority of the residential filters have been installed.
SUMMARY OF THE PREFERRED ALTERNATIVE
Based on new information and methods of characterizing landfill gas permeability and concentrations, since the ROD was signed, PRPs, under the oversight of EPA and in consultation with the PADEP, developed an Alternate Source Control Remedy that meets the remedial action objectives presented in the 1990 ROD and provides protection of human health and the environment. The preferred alternative includes:
A. General Description of the Alternate Source Control Remedy
The primary components of the Alternate Source Control Remedy are described below.
- Upgrades to the existing landfill soil cover;
- Installation and operation of an ELGE system to actively remove VOCs and methane from the landfill waste;
- Monitoring to ensure proper functioning of the ELGE system and to evaluate VOC removal from the landfill;
- Monitoring to determine the impact of the ELGE system on the quality of the leachate within the landfill;
- Use of surface water management controls to minimize soil erosion and sedimentation;
- Maintenance of the existing fence; and
- Use of deed restrictions on the landfill property.
1. Upgrades to the Existing Soil Cover
Upgrades to the existing landfill cover will include:
- Addition of low permeability cover soil to maintain a minimum 2-foot thick soil coveracross the landfill;
- Regrading of the landfill surface to repair minor erosion gullies, improve drainage, and ensure adequate slope stability; and
- Removal of woody vegetation.
A comprehensive investigation of the landfill cover thickness will be performed. Areas of the landfill soil cover having a thickness of less than 2 feet will be increased to at least 2 feet using compacted soils. The cover will then be re-vegetated. A waste investigation will be performed to verify the boundaries of the landfill. The cover upgrades will also address waste discovered outside the boundaries of the landfill.
Areas of the landfill where surface water ponding has occurred will be regraded to promote positive drainage of surface water off the landfill. Areas where erosion has occurred will be repaired with cover soil which will be re-vegetated to prevent future erosion. These areas will be inspected and evaluated to determine whether specific additional surface water management controls are needed. Woody plants from the small tree-covered portion of the landfill will be removed via flush cutting or controlled application of herbicides, and new cover soil will be revegetated. The steeper areas of the landfill (exceeding 15 degrees slope angle) will be evaluated for slope stability.
A comprehensive inspection, maintenance and monitoring (O&M) plan will be implemented to assure that the upgraded cover will continue to function effectively in the future.
2. Enhanced Landfill Gas Extraction
The 1990 ROD requires installation of a methane collection system, and treatment of the methane using a flare. Pursuant to the ROD, the approved design provides for methane to be collected through a series of gas extraction wells. The system is designed to control migration of methane.
Under the proposed ELGE system, VOCs and methane will be extracted from the landfill, and the removal of the landfill gas will help to further remove some of remaining VOCs from the landfill waste.
In the currently approved landfill cap/methane control design, 16 wells are proposed in order to capture methane gas generated by the landfill. The Alternate Source Control Remedy proposes the following enhancements:
- The installation of additional and deeper wells for the removal of VOCs and control of methane;
- Increased blower and flare capacities;
- Iterative design and installation of the well network;
- Innovative site characterization and optimization of well design and locations using a combination of recently developed technology, site reconnaissance (e.g., soil borings), and results of previous studies;
- Installation of landfill gas monitoring points;
- Optimization of ELGE well operation using techniques such as flow balancing, staggering operation of wells, and cycling of wells;
- Condensate collection and treatment by injection into the flare; and
- Evaluation of bioventing as a future modification.
Each of these enhancements is further described below and a conceptual design for the initial ELGE system is presented in Figure 2. The initial design is based upon the USEPA-approved methane management system design with additional ELGE wells in the area of the Pilot Study. The proposed location for the blower and flare building is south of the current groundwater treatment building. Alternate locations adjacent to the landfill may be considered. Also, the location and number of wells may change during the ongoing design process. During the design of the proposed remedy, an evaluation will be performed to determine the number and location of the ELGE wells, associated monitoring wells and leachate monitoring points.
The installation of additional extraction wells will provide increased VOC removal in areas with elevated contaminant concentrations. Each well will be equipped with its own flow control valve, so that extraction vacuums and flow rates can be individually monitored and modified. To some extent, gas removal can be increased by increasing the flow rate at an individual well, thereby expanding the gas capture zone. However, potential infiltration of ambient air through the soil cover and sidewalls of the landfill may limit the practical radius of influence of a well. The horseshoe shape of the landfill contributes to this constraint, due to the proximity of any point in the landfill to the landfill walls. Excessive air infiltration is undesirable for three reasons:
- The current oxygen poor/methane rich environment of the landfill supports microbes that degrade the waste within the landfill, introducing oxygen into the landfill may disrupt this degradation process;
- Excessive oxygen may cause the landfill temperature to rise and increase the potential for fire within the landfill; and,
- The introduction of air into the system will add volume and dilute the gas being collected and treated. The consequent reduction in the heating value of the gas may necessitate the use of supplemental fuel at the flare.
Therefore, the provision of additional wells will allow increased extraction rates while reducing the intrusion of ambient air into the landfill and the extraction system. The November 1998 ELGE Pilot Study showed that 25 scfm can be sustained in an extraction well without excessive ambient air infiltration. The blower and flare system will be appropriately sized to extract and treat the increased VOC removal.
The iterative approach to well installation will consist of initially installing a group of methane management wells which will likely be similar to the currently approved design that included a total of 16 methane management wells. Additionally, the first phase (as shown in Figure 2) will involve additional ELGE wells in the vicinity of the Pilot Study location and other areas determined to contain elevated levels of VOCs. Subsequent phase(s) may involve additional wells or increased extraction rates based on the first phase.
Innovative Site Investigation
The use of enhanced site investigation techniques will allow the study of gas flows and VOC concentrations with depth in each well. This will yield important information as to the composition and physical characteristics of the waste to be treated. Other relevant information, such as the previous soil gas grid survey for methane and any available historical records, may yield information about VOC source areas and the types, locations, and deposition practices for waste. This information will guide the design of subsequent phases in terms of locating VOC and/or methane removal wells, targeting specific areas within the waste, and optimizing well depths in order to enhance methane/VOC removal while limiting air infiltration.
Gas flow rates and vacuums will be monitored and balanced in wells in order to enhance the methane and VOC content in the extracted gas, thereby increasing the overall system efficiency. Additional measures may include staggering the operation of wells or cycling wells on and off. Staggered operation would allow the temporary or permanent shutdown of wells that have substantially completed VOC and/or methane removal in their associated capture zones. Cycling would allow the entire well field or portions thereof to be temporarily shut off in order to allow additional diffusion of VOCs into the landfill gas for subsequent removal.
The gas treatment flare is proposed to be equipped with a condensate injection system. Such systems are operating at about 15 sites in the United States, most of which are landfills. Using compressed air, the condensate is injected via a nozzle into the flare, slightly above the flame level. Recent stack test data indicate that the addition of condensate injection to an enclosed flare has no adverse effect on the operation of the flare or the emissions from the flare. During the design phase, estimated VOC emissions from the flare will be calculated based on expected flare destruction efficiency and the concentrations of VOCs in the extracted gas and condensate measured during the Pilot Test.
Evaluation of Bioventing
The use of bioventing as an additional innovative system enhancement will be considered as operational experience is gained. Bioventing is an innovative technology that has been employed mostly at petroleum contaminated sites and involves the use of existing subsurface microorganisms to biodegrade organics under oxygen rich conditions. The process typically involves the addition of air (oxygen), nutrients, and water to the system. It is most often used at sites contaminated with mid-weight petroleum products, since lighter products will volatilize easily under SVE and heavier products tend to take longer to biodegrade. If operational data indicates bioventing may be applicable, it will be evaluated.
3. Monitoring to determine the impact of the ELGE system on the quality of the leachate within the landfill
ELGE extraction wells shall create capture zones where the VOC contamination is removed from the landfill and shall prevent migration of VOCs to the groundwater beneath the landfill. Leachate monitoring points shall be installed in the landfill to monitor the impact of the ELGE system on the quality of the leachate within the landfill. The ELGE system shall reduce VOC contamination in the leachate within the landfill to the selected performance standards for the contaminants of concern (COC). The performance standards for the COC are in Table 1.
4. Upgrades to the Storm Water Management System
Surface water drainage improvements, such as channels on and around the landfill, will be designed and constructed to convey the peak runoff from a 25-year 24-hour storm event safely away from the landfill to protect the cover and reduce infiltration in and around the landfill. Over 2,000 linear feet of additional rip-rap lined channel and an additional detention basin, or similar measures to be evaluated during design, would be placed on the southern side of the Site. The surface water drainage improvements will also address runoff onto adjacent properties.
5. Maintenance of the existing fence
The existing fence will be maintained. However, in areas where the limits of the waste in the landfill may extend beyond the existing fence, the fence will be relocated to the true perimeter of the landfill.
6. Use of deed restrictions on the landfill property
The 1990 ROD called for deed restrictions on the Site without specifying the exact location where the deed restrictions were to be placed. This Proposed Plan recommends that the deed restrictions be limited to the landfill itself and not extend to other portions of the Site, including those portions of the Site used for residential purposes.
7. Post-Construction Monitoring
As part of the remedy, an Operations and Maintenance Plan (O&M) will be developed. Monitoring components of the O&M Plan shall include annual inspections of the upgraded soil cover to determine the adequacy of erosion controls, surface water runoff controls, and vegetation. The O&M Plan shall also include maintenance of the vegetative cover, including mowing and seeding as necessary. In addition, the O&M plan shall include details for monitoring the ELGE system and the leachate near the ELGE wells to evaluate the effectiveness of the Alternate Source Control Remedy. For the ELGE system, monitoring will include the following components:
- Monitoring at individual extraction wells and monitoring points, as appropriate, for vacuum, flow rate, temperature, and concentrations of methane, oxygen, carbon dioxide, nitrogen, water content, and individual VOC constituents;
- Sampling of the combined extracted gas for analysis of individual VOC constituents and methane;
- Flare VOC emissions based on calculations using the analyzed influent stream and the destruction efficiency of the flare;
- Condensate generation rates, total accumulation, and injection rates to the flare;
- VOC analysis of condensate;
- Calculated mass removals of VOCs; and
- Monitoring of leachate within the landfill.
Remedial Action Objectives
The selected remedy will actively remove VOCs from the landfill. The main goals of this proposed remedy are to: 1) prevent migration of site-related contaminants from the landfill that could result in groundwater concentrations in excess of performance standards; 2) prevent future releases of contamination into surface water and sediments; 3) prevent direct contact with contaminated soil and waste; and 4) control methane build-up and migration in the landfill. In combination with the planned remedial actions selected in the 1990 ROD (that are not being changed by this proposal), this remedy will satisfy the remedial objectives for this Site and be effective in capturing, containing, and cleaning up the contaminants in the landfill and the groundwater to the performance standards, while protecting human health and the environment.
The Alternate Source Control Remedy and previous remedial actions will be evaluated during each Five Year Review.
In addition, this Proposed Plan includes performance standards for the proposed Alternate Source Control Remedy. Each of the components of the proposed remedy and its performance standards are described in detail below.
B. Performance Standards
The installation of an ELGE system is expected to significantly increase VOC removal rates over groundwater extraction alone. The VOC concentrations observed during the Pilot Test, however, are not necessarily representative of the entire landfill, and it is, therefore, not appropriate to establish a VOC removal performance standard based on those values. Further, it is expected that the rate of VOC removal will decline over time as the source is depleted. The following performance standards are proposed for the cessation of enhanced VOC removal (continued system operation for methane migration control shall be required, see Methane Extraction below):
Based on baseline sampling of monitoring points prior to startup, achieve 90% reduction 1 in concentration of selected target VOC compounds, at the monitoring points, at least 48 hours after the extraction system has been shut down to allow for concentration rebound; and,
[1. Not to be less than the Practical Quantitation Limits (PQLs)]
ELGE extraction wells shall create capture zones where the VOC contamination is removed from the landfill in vapor phase and shall prevent migration of VOCs from the landfill to the groundwater in excess of performance standards. Leachate monitoring points shall be installed in the landfill near ELGE wells to monitor the impact of the ELGE system on the quality of the leachate within the landfill. The ELGE system shall reduce VOC contamination in the leachate within the landfill to the selected performance standards for the contaminants of concern (COC). The performance standards for the COC are set forth in Table 1.
The potential impact of leachate on groundwater contaminant levels was assessed by USEPA via modeling. USEPAs BIOCHLOR model was used to estimate acceptable leachate concentrations at anticipated ELGE leachate monitoring points. The goal was to determine leachate concentrations that would not result in exceedances of the groundwater performance standards at the points of compliance. Lack of field data regarding leachate quality and quantity required that several assumptions be made in the modeling effort. These include, but are not limited to, assumptions that 1) no unsaturated zone exists between leachate and the groundwater; 2) groundwater monitoring data from Well K1 is indicative of leachate concentrations in the landfill; and 3) there will be a two hundred foot distance from the ELGE leachate monitoring points to the point of compliance. Field conditions will be investigated and evaluated during the remedial design. To the extent that actual conditions differ from the modeling assumptions, it may be appropriate to re-evaluate the leachate performance standards. Therefore, after four quarters of field data have been collected, this data may be re-entered into the BIOCHLOR model (or substantially similar model) to develop revised leachate performance standards. Revised leachate performance standards at ELGE monitoring points, based on the above field data and modeling, will be subject to the approval of USEPA in consultation with PADEP. Leachate performance standards may be made more stringent, if USEPA determines, based on reasons other than failure to meet groundwater standards, that more stringent standards are necessary to protect human health or the environment.
The leachate performance standards apply only to leachate. The groundwater is subject solely to performance of the groundwater remedy and attainment of groundwater performance standards at points of compliance. Based on field observations made during the pilot tests and on historical data, in certain portions of the landfill which require treatment using ELGE, measurable leachate may not be present at the leachate monitoring points. To the extent no measurable leachate is present at leachate monitoring points, leachate performance standards may be waived at those locations. USEPA's decision to waive leachate performance standards shall be based upon the results from the monitoring network established during design. Further, if after field investigation, USEPA determines that it is not possible to distinguish leachate from groundwater, the leachate performance standards may be waived. In no event will ELGE be required to address source areas located below the water table.
Leachate samples will be collected and analyzed quarterly in year one and semi-annually thereafter. Based upon the results, collection and analysis of these data may be modified as determined by EPA, in consultation with PADEP. The monitoring locations will be determined by EPA, in consultation with PADEP, during future design activities. The ELGE system shall operate until performance standards are achieved for all selected COCs at the leachate monitoring points.
The preceding performance standards may be used for cessation of enhanced VOC removal in individual wells, clusters of wells, or ultimately the entire ELGE system.
2. Methane Extraction
The 1990 ROD stated that as part of the selected remedy, an active gas extraction system would be installed in compliance with 25 PA Code Section 273.292. For the methane extraction and control portion of the ELGE system, a demonstration of compliance with the following state standards is proposed:
Following shutdown of the system or portions thereof, four consecutive sets of methane monitoring at the landfill perimeter, spaced no less than three months apart, show that:
- 25% of the lower explosive limit for methane is not exceeded within nearby structures; and
- The lower explosive limit for methane is not exceeded at the landfill boundaries.
The nearby structures in this case will comprise existing on-site buildings and the Groundwater Treatment Plant building.
3. Soil Cover
The Alternative Source Control Remedy proposes to up grade the existing soil cover to a minimum 2 foot thickness across the landfill with soils of similar properties to those of the existing cover. Analyses by Golder on the existing cover indicate that the average permeability of current cover soils is 2.2 x 10-6 cm/sec. At a minimum, areas having a thickness of less than two feet shall be upgraded to 18 inches of soils having an average permeability no greater than 2.2 X 10-6 cm/sec, and a maximum permeability no greater than two times this value, overlain with a minimum 6 inch erosion layer.
4. Surface Water/Drainage
Surface water drainage improvements, such as channels on and around the perimeter of the landfill, will be designed and constructed to convey the peak runoff from a 25-year 24-hour storm event safely away from the landfill to protect the cover and reduce infiltration in and around the landfill.
5. Post-Construction Monitoring
As part of the Remedial Action, an Operations and Maintenance Plan (O&M) will be developed. Monitoring components of the O&M Plan shall include annual inspections of the upgraded soil cover to determine the adequacy of erosion controls, surface water runoff controls, and vegetation. The O&M Plan shall also include maintenance of the vegetative cover, including mowing and seeding as necessary. For the ELGE system, monitoring would include the following components:
- Monitoring at individual extraction wells and/or monitoring points, as appropriate, for vacuum, flow rate, temperature, and concentrations of methane, oxygen, carbon dioxide, nitrogen, water content, and individual VOC constituents to evaluate compliance with performance standards;
- Sampling of the combined extracted gas for analysis of individual VOC constituents and methane;
- Flare VOC emissions based on calculations using the analyzed influent stream and the destruction efficiency of the flare;
- Condensate generation rates, total accumulation, and injection rates to the flare;
- VOC analysis of condensate;
- Calculated mass removals of VOCs; and
- Monitoring of leachate in close proximity to wells being utilized for VOC removal.
6. Periodic Monitoring and ELGE System Shutdown
Once the ELGE system is operational and functional, individual ELGE extraction wells, ELGE monitoring points, and leachate monitoring points shall be sampled and analyzed quarterly in year one and semi-annually thereafter.
Based upon the results, collection and analysis of these data may be modified as determined by EPA, in consultation with PADEP. Monitoring shall be conducted at the ELGE extraction wells, nearby ELGE monitoring points, and leachate monitoring points to provide information as to the effectiveness of the ELGE system. The monitoring locations will be determined by EPA during future design activities.
The decision to discontinue operation of an individual ELGE extraction well, or to discontinue operation of the entire ELGE system, shall be made as follows:
- If an ELGE extraction well, related ELGE monitoring points and leachate monitoring points all meet the respective performance standards during two consecutive semi-annual monitoring events, the operation of that particular ELGE extraction well may be temporarily discontinued, upon approval by EPA in consultation with PADEP, and subject to the confirmatory monitoring requirements detailed in subparagraph b below. (Continued system operation for methane migration control shall be required, see Methane Extraction above.)
- Once an ELGE extraction well, related ELGE monitoring points, and leachate monitoring points all have met the respective performance standards for two consecutive semi-annual monitoring events, monitoring of these sampling locations shall increase to quarterly. If the performance standards continued to be achieved for eight consecutive quarters and no statistically significant trends are observed in the data indicating a future exceedance of the performance standards could occur, then that particular ELGE extraction well may shut down, upon approval by EPA in consultation with PADEP. If at anytime during the eight quarters of sampling, the ELGE system fails to achieve performance standards or statistically significant trends are observed in the data indicating a future exceedance of the performance standards could occur, then the ELGE extraction well shall be reinitiated. (Continued system operation for methane migration control shall be required, see Methane Extraction above.)
- The system may be shut down in a phased manner as portions of the ELGE system achieve compliance with performance standards. (Continued system operation for methane migration control shall be required, see Methane Extraction above.) A long-term monitoring program, which will be approved by EPA, shall be instituted.
TABLE 1: LEACHATE QUALITY PERFORMANCE STANDARDS
|Contaminants of Concern||Groundwater Performance Standards (ug/L)||Leachate Performance Standard (ug/L)|
- Leachate Performance Standards based on USEPA BIOCHLOR model; specific input assumptions subject to field verification (see text).
- Leachate Performance Standards not required for ethanes and other groundwater constituents of concern (based on maximum detected concentrations and USEPA BIOCHLOR model; specific input assumptions subject to field verification (see text)).
- Leachate Performance Standards will not be required for Iron and Manganese.
In order to optimize the efficiency of the ELGE Remedy additional measures to augment or supplement the ELGE Remedy may be implemented. Such measures may include, but are not limited to: installing additional ELGE wells, expanding the blower capacity, balancing the extraction flow rates at individual wells, and modifying the off-gas treatment system.
In the event that ELGE Remedy fails to meet the performance standards specified above, a Contingent Remedy shall be implemented at the Site. The Contingent Remedy will be equally protective of human health and the environment as the ELGE Remedy and will be either an Enhanced Containment Remedy or an Enhanced In-situ Treatment Remedy. The performance data that are used to determine ELGE Remedy failure will also be used, in conjunction with other relevant data, to determine which of the Contingent Remedies below will be implemented. A short description of each of the Contingent Remedies and their anticipated performance at the Site is provided below.
Enhanced Containment Remedy
The first potential Contingent Remedy involves enhanced containment. Pursuant to this Contingent Remedy, a further upgrade to the landfill closure cover would be constructed in areas of the landfill that receive most infiltration of storm water, in order to reduce the quantity of leachate generated from the landfill. This shall be achieved by placing a geosynthetic membrane overlain by a drainage layer and vegetated layer on the top portion of the landfill where slopes are less than 15 percent and infiltration is potentially greatest. Construction of such a cover would reduce infiltration by approximately 75% of the present values. The methane management system would continue to function as part of this contingent remedy.
Enhanced In-Situ Treatment Remedy
A second Contingent Remedy involves enhanced in-situ treatment. Pursuant to this Contingent Remedy, enhanced in-situ treatment will be achieved by leachate recirculation and/or addition of water and air to the landfill. Leachate would be extracted from the existing ELGE wells or other collection systems constructed expressly for this purpose. This approach is expected to result in enhanced biodegradation of VOCs in the landfill. The methane management system would continue to function as part of this Contingent Remedy as long as required.
Compliance with National Contingency Plan Criteria
The following section provides an evaluation of the Alternate Remedy and the Contingent Remedies against the NCP criteria. The Contingent Remedies satisfy the NCP threshold criteria and are equal to the 1990 ROD Remedy on the basis of all the balancing criteria, excluding State and Community Acceptance which will be addressed following the comment period.
EVALUATION OF THE ALTERNATE SOURCE CONTROL REMEDY AND THE CONTINGENT REMEDIES USING THE NINE NCP CRITERIA
The ROD Remedy, the proposed Alternate Source Control Remedy, and the proposed Contingent Remedies have been evaluated according to the nine criteria in the NCP 40 C.F.R. 300.430(e)(9) as set forth in Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA (EPA, October 1988), and Guidance on Preparing Superfund Decision Documents: The Proposed Plan, The Record of Decision, Explanation of Significant Differences, and the Record of Decision Amendment (EPA/540/6-89/007, July 1989 Interim Final). The alternative described in this proposed plan was evaluated using the nine criteria set forth in 40 C.F.R. § 300.430 (e)(9)(iii), as a supplement to the evaluation performed in connection with the 1990 ROD, as amended in June 1999. These nine criteria can be further categorized into three groups: threshold criteria, primary balancing criteria, and modifying criteria, as follows:
- Overall protection of human health and the environment
- Compliance with applicable or relevant and appropriate requirements (ARARs)
Primary Balancing Criteria
- Long-term effectiveness
- Reduction of toxicity, mobility or volume through treatment
- Short-term effectiveness
- Community Acceptance
- State Acceptance
These evaluation criteria relate directly to requirements in Section 121 of CERCLA, 42 U.S.C. § 9621. Threshold criteria must be satisfied in order for a remedy to be eligible for selection. Primary balancing criteria are used to weigh major trade-offs between alternatives. Acceptance by the State and Community are modifying criteria formally considered after public comment is received on the Proposed Plan. A discussion of each criterion relative to both the 1990 ROD Remedy, the proposed Alternate Source Control Remedy and the Contingent Remedies is presented below.
Overall Protection of Human Health and the Environment
The overall protectiveness criterion evaluates whether or not an alternative provides adequate protection to human health and the environment by eliminating, controlling or reducing the current and potential exposures to levels established as remediation goals.
Both the ROD Remedy and Alternate Source Control Remedy are expected to achieve overall protection of human health and the environment. The ROD Remedy, construction of an impermeable cap, would reduce dermal exposure risks and groundwater contamination through containment of the waste.
In combination with the other components of the 1990 ROD as amended on June 25, 1999, the Alternate Source Control Remedy is expected to achieve overall protection of human health and the environment because removal and treatment of VOCs from the landfill will effectively prevent the migration of VOCs from the landfill that could result in groundwater concentrations in excess of performance standards and, thereby, provide control of the source. Further, removal and treatment of VOCs in the gas phase from the landfill will remove these contaminants as a potential source of contamination of other pathways.
The Contingent Remedies, in combination with the groundwater collection and treatment remedy, will also provide protection by enhancing containment or treatment of contaminants so as to prevent migration that could result in groundwater concentrations in excess of cleanup standards.
The ROD Remedy and the Alternate Source Control Remedy are protective of human health and the environment. The Alternate Source Control Remedy relies upon removal of the source whereas the ROD Remedy relies upon source containment through the installation of the impermeable cap.
Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)
The compliance with ARARs criterion evaluates whether the alternatives would meet all of the applicable or relevant and appropriate requirements of other environmental statues and/or provide grounds for involving a waiver. Under Section 121 (d) of CERCLA, 42 U.S.C. Section 9621 (d), remedial actions must attain ARARs unless such ARARs may be waived under CERCLA Section 121 (d) (4), 42 U.S. C. Section 9621 (d) (4).
Section 121(d) of CERCLA requires that remedial actions at CERCLA sites at least attain legally applicable or relevant and appropriate cleanup standards, standards of control, and other substantive environmental protection requirements, criteria or limitations promulgated under Federal or State law, which are collectively referred to as "ARARs", unless such ARARs are waived under CERCLA§ 121(d)(4).
Applicable requirements are those cleanup standards, standards of control, and other substantive environmental protection requirements, criteria or limitations promulgated under Federal or State law that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance at a CERCLA site. Relevant and appropriate requirements are those requirements that, while not legally applicable, address problems or situations sufficiently similar to those encountered at the site that their use is well suited to the particular site. Only those State standards that are promulgated, are identified by the State in a timely manner, and are more stringent than federal requirements may be applicable or relevant and appropriate. ARARs may relate to the substances addressed by the remedial action (chemical-specific), to the location of the site (location-specific), or the manner in which the remedial action is implemented (action-specific).
In addition to applicable or relevant and appropriate requirements, the lead agency may, as appropriate, identify other advisories, criteria, or guidance to be considered for a particular release. The "to be considered" (TBC) category consists of advisories, criteria, or guidance that were developed by EPA, other federal agencies or states that may be useful in developing CERCLA remedies.
The identification of ARARs in this proposed plan supplements the discussion of ARARs developed in the FS, the September 1990 ROD, and the 1999 ROD Amendment for Groundwater. The ARARs identified in this proposed plan relate only to the response actions addressed in this document; ARARs relating to response actions selected in the 1990 ROD or the 1999 ROD Amendment for Groundwater but not addressed in this proposed plan are not discussed. Furthermore, ARARs identified in the 1990 ROD or the 1999 ROD Amendment for Groundwater, which relate to the response actions proposed are incorporated by reference herein. Reference should be made to the discussion of Site ARARs in the 1990 ROD and the 1999 ROD Amendment for Groundwater for a complete discussion of all chemical-, location- and actionspecific ARARs for the Site.
The following discussion identifies the ARARs and TBCs identified by EPA (after submission to the Commonwealth of Pennsylvania and the State of Maryland for review and comments) relating to the remedy proposed herein. On-site actions (i.e., within the areal extent of contamination and all suitable areas in very close proximity to the contamination necessary for implementation of the response action) need comply only with the substantive aspects of ARARs, not with the corresponding administrative requirements (e.g., consultation, issuance of permits, documentation, record keeping and enforcement).
Action Specific ARARs
- Air Resources, Pennsylvania Code, Title 25, Sections 121.7, 121.9, 123.1, 123.2, 123.21, 123.31, 123.41-123.43, and 127.1 which are applicable to fugitive dust control, use of Best Available Technology (BAT), emissions of specific air pollutants. These regulations are applicable to the air pollution control measures to be employed during work associated with the upgrading of the soil cover as part of the Alternate Source Control Remedy or the Contingent Remedies, as well as emissions from the ELGE system or the Contingent Remedy treatment system.
- Pennsylvania Municipal Waste Landfill Regulations, Pennsylvania Code Title 25, Sections 273.234(a)(3),(c),(e), 273.235, 273.236, 273.241-244 which are applicable to the work associated with the upgrading of the soil cover as part of the Alternate Source Control Remedy or the Contingent Remedies.
- Pennsylvania Municipal Waste Landfill Regulations, Pennsylvania Code Title 25, Section 273.292. This regulation is applicable to the operation of the ELGE remedy as a methane control system and to the methane control system that is part of the Contingent Remedies.
Long-Term Effectiveness and Permanence
The long-term effectiveness criterion evaluates the long-term protection of human health and the environment over time, once the remedial action goals have been achieved. It focuses on the magnitude of residual risk and the adequacy and reliable of controls of the alternatives.
The ROD Remedy and the Alternate Source Control Remedy provide for long-term effectiveness equally with respect to contact with contaminated landfill waste and soils.
Both remedies include the soil cover, which provides long-term protection against contact with contaminated landfill waste and soils.
The impermeable cap required by the ROD Remedy would reduce the amount of VOC contamination reaching the groundwater in the short-term but would not significantly reduce the mass of VOCs at the Site over time since most of the VOCs would remain under the cap.
The Alternate Source Control Remedy would be more effective in the long-term than the ROD Remedy for several reasons. The Alternate Source Control Remedy provides long-term and effective protection of human health and the environment because it provides for the effective removal and treatment of VOC from the landfill, thereby, eliminating these compounds as potential contaminants. In addition, operation, inspection, monitoring, and maintenance will be regularly conducted to ensure the components of the Alternate Source Control Remedy perform effectively in the future.
Thus, because more VOCs would ultimately be removed from the landfill under the Alternate Source Control Remedy, it provides greater long-term effectiveness and permanence. Additionally, the landfill would be covered with 2 feet of soil and deed restrictions placed on those areas to control future contact with contaminated landfill material. The overall time frame to restore the ground water is not expected to be significantly different for the ROD and the Alternate Source Control Remedy.
The Contingent Remedies also provide long-term and effective protection by enhanced containment or treatment of VOCs.
Reduction of Toxicity, Mobility, or Volume Through Treatment
This criterion evaluates the performance of the alternatives to reduce the toxicity, mobility and volume of waste by assessing the degree of irreversibility and the types and quantity of residuals remaining.
Under the ROD Remedy, the mobility of VOCs in the landfill waste would be decreased by placement of the impermeable cap. The ROD remedy did not address the CERCLA statutory preference for treatment of the waste as, at the time of the ROD, it was determined to be impracticable.
The Alternate Source Control Remedy satisfies the CERCLA statutory preference for treatment technologies to be used in a remedial action to a much greater extent than does the impermeable cap source control remedy selected in the ROD. The removal and treatment of VOCs via the ELGE system will provide a significant reduction of the toxicity, mobility and volume of contaminants within the landfill. In combination with the groundwater remedy the Alternate Source Control Remedy is expected to dramatically reduce the concentration of contamination in the groundwater to levels that at least meet groundwater clean up standards.
Thus, the Alternate Source Control Remedy is superior to the ROD Remedy in terms of reduction in toxicity. The Alternative Remedy more effectively reduces volume through treatment while allowing a limited, but controlled increase in mobility.
The Contingent Remedy which utilizes the Enhanced In-Situ Treatment Remedy option satisfies the statutory preference for treatment. The Enhanced Containment Remedy in combination with the groundwater collection and treatment remedy will satisfy the statutory preference for treatment.
Short-term effectiveness evaluates the alternatives against the period of time needed to achieve protection of human health and the environment and any adverse impacts that may be posed during the construction and implementation period, until clean-up goals are achieved.
The Alternate Source Control Remedy involves a limited amount of heavy construction, as a result, there is a much reduced level of environmental impact, quality of life impact and aesthetic concerns for nearby residents, and worker health and safety risks associated with the Alternate Source Control Remedy compared to the ROD Remedy. The remaining impacts are expected to be low level and short-term and can be properly controlled during construction so as to not anticipated to result in adverse long-term effects.
The ROD remedy, construction of an impermeable cap, would likely take longer to achieve protectiveness due to the estimated construction time for the cap. It would also involve more intrusive activities during construction.
The Enhanced Containment Contingent Remedy will involve greater short-term risks than the Alternate Source Control Remedy due to the greater extent of heavy construction. The Enhanced In-Situ Treatment Contingent Remedy will minimize short term impacts in the same manner as the Alternate Source Control Remedy.
The Implementability evaluation criterion consists of several sub-components, including those which evaluate the compatibility of remedial measures with site conditions, availability of materials and services, ability to undertake further remedial actions if necessary, and regulatory considerations.
The implementation of the Alternate Source Control Remedy is considered to be straightforward. The cover upgrades, storm water controls, vegetation repairs, and landfill gas extraction and treatment technologies are well-established practices and the services and materials to construct these facilities are standard in the industry and readily available. Although aspects of ELGE are considered innovative, the recent pilot test at the Site confirms that it can be effectively installed and operated. Other innovative aspects of the project, such as the use of PneuLog and evaluation of bioventing, may further enhance the speed and success of the remedy but do not affect the overall Implementability. Overall, no technical or administrative problems are envisioned which would adversely affect the construction or schedule for implementation of this alternative. Similarly, long-term operation and maintenance requirements can be easily performed.
Even though there are engineering concerns related to the implementation of the Alternate Source Control Remedy, they are far less complicated than the ROD Remedy which requires the installation of an impermeable cap. Based on the above, the Alternative Remedy is preferred on the basis of Implementability.
No technical or administrative problems are envisioned which would adversely affect the construction or schedule for implementation of the Contingent Remedies and long-term operation and maintenance can be readily performed.
The cost evaluation criterion considers the estimated cost for the capital and operation and maintenance (O&M) of the alternatives on a present worth basis. Table 2 provides the estimated cost for implementing all of the components for the Alternate Source Control Remedy. The total estimated present worth cost for this alternative is $5,500,000.
The proposed alternative is cost-effective in providing overall protection in proportion to cost, and meets all other requirements of CERCLA. Section 300.430(f) (ii) (D) of the NCP requires EPA to evaluate cost-effectiveness by comparing alternatives which meet the threshold criteria - protection of human health and the environment and compliance with ARARs - against three additional balancing criteria: long-term effectiveness and permanence; reduction of toxicity, mobility or volume through treatment; and short-term effectiveness. The selected remedy meets these criteria and provides for overall effectiveness in proportion to its cost.
This criterion indicates whether the state concurs with, opposes, or has no comment on the preferred remedy. State acceptance of the preferred alternative will be evaluated at the conclusion of the public comment period and will be addressed in the Amendment to the Record of Decision.
This criterion will be addressed in the Amendment to the Record of Decision following EPAs review of the communitys comments on the Proposed Plan and supporting documents included the administrative record for the Site.
COMMUNITY ROLE IN THE SELECTION PROCESS
EPA is soliciting written comments from the community on the proposed amendment to the ROD, as set forth in this Proposed Plan and the FFS. The public comment period is from June 5, 2000 through July 5, 2000. The comment period will include a public meeting where EPA will discuss this Proposed Plan and supporting documents, answer questions, and accept oral and written comments from the public. The public meeting is scheduled for June 22, 2000, at 7:00 p.m. and will be held at the Abbottstown Fire Company Hall.
Following the conclusion of the thirty (30) day public comment period on this Proposed Plan, a Responsiveness Summary will be prepared and included in the amendment to the ROD. The Responsiveness Summary will summarize comments from the public on EPAs Preferred Remedial Alternative and EPAs Responses to these comments. Copies of the ROD Amendment will be made available for public review in the information repository. Please submit written comments to:
Ms. Kelley A. Chase (3HS21)
U.S. Environmental Protection Agency
1650 Arch Street
Philadelphia, Pennsylvania 19103-2029
All comments must be postmarked on or before July 5, 2000.
TABLE 2: COST ESTIMATE
KEYSTONE SANITATION LANDFILL
UNION TOWNSHIP, PENNSYLVANIA
|Activity||Quantity Unit||Unit Price||Activity Cost|
|Performace Bond||1 Lump||$50,000.00||$50,000.00|
|Design Engineering (5%)||1 Lump||$160,000.00||$160,000.00|
|Erosion & Sediment Control||1 Lump||$115,000.00||$115,000.00|
|Clearing & Grubbing||20 Acres||$2,250.00||$2,250.00|
|Vegetation Disposal (Organics Only)||1 Lump||$22,000.00||$22,000.00|
|Subgrade Preparation||1 Lump||$55,000.00||$55,000.00|
|Vegetative Layer||12500 CY||$10.00||$125,000.00|
|Access Road||1250 CY||$34.00||$42,500.00|
|Stormwater Management System||1 Lump||$395,000.000||$395,000.000|
|Detention Basin||1 Lump||$85,000.00||$85,000.00|
|Gas Extraction System||1 Lump||$1,082,000.00||$1,082,000.00|
|See, Sod & Re-Vegetation||1 Lump||$38,000.00||$38,000.00|
|Fence Repairs||1000 LF||$17.96||$44,000.00|
|Health & Safety/Construction QC||1 Lump||$48,000.00||$48,000.00|
|Capital Cost Total||$2,571,500.00|
|Contractor General Overhead & Profit (15%)||$383,000.00|
|(Present Worth Value) Total Cost||$5,500,000.00|
GLOSSARY OF TERMS
- Administrative Record
- An official compilation of site-related documents, data, reports, and other information that is considered important to the status of and decisions made relative to a Superfund site. The public has access to this material.
- Applicable or Relevant and Appropriate Requirements (ARARs)
- The federal and state requirements that a selected remedy must attain, unless they are waived. These requirements may vary among sites and remedial alternatives.
- Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
- A federal law passed in 1980 and modified in 1986 by the Superfund Amendments and Reauthorization Act (SARA). The Act created a trust fund, known as Superfund, to investigate and clean up abandoned or uncontrolled hazardous substance facilities.
- Focused Feasibility Study (FFS)
- A feasibility study that identifies and evaluates alternatives for addressing contamination at a hazardous substance facility. The FFS is a streamlined study that evaluates a limited number of alternatives for a specific problem at the facility.
- Water found beneath the earths surface in geologic formations that are fully saturated. When it occurs in sufficient quantity, groundwater may be used as a water supply.
- A liquid that results from water collecting contaminants as it percolates though waste and may result in hazardous substances entering surface water, groundwater, or soil.
- National Priorities List (NPL)
- EPAs list of the nations top-priority hazardous substance facilities that may be eligible to receive federal money for response under CERCLA.
- Operable Unit (OU)
- A discrete portion of a site or a discrete action representing an incremental step in the investigation and remediation of hazardous substances at a facility.
- Present Worth
- A term used to indicate the discounting of sums to be received in the future to their present value equivalent or the amount that will accumulate to that sum if invested at prevailing interest rates.
- Record of Decision (ROD)
- A legal document that describes the remedy selected for a Superfund facility, why the remedial actions were chosen and others not, how much they cost , and how the public responded.
- Remedial Investigation (RI)
- A study performed to identify the nature and extent of contamination at a hazardous substance facility. The RI is used in conjunction with the feasibility study to support the selection of a remedy for the site.
- Scientific Notation
- Method used to express numerical values. For example, one million (1,000,000) is expressed as 1.0E+06. One, one-millionth (or one in one million) (0.000001) is expressed as 1.0E-06.
- See CERCLA.
- Volatile Organic Compounds (VOCs)
- Organic liquids [e.g., trichloroethene (TCE)] that readily evaporate under atmospheric conditions.
If you did not receive this Proposed Plan for the Keystone Sanitation Landfill in the mail and wish to be placed on the mailing list for future information pertaining to this site, please fill out, detach, and mail this form to:
Mr. Hal Yates (3HS43)
U.S. Environmental Protection Agency
1650 Arch Street
Philadelphia, Pennsylvania 19103-2029