National Cooperative Refinery

Association/CHS Refinery

An aerial photograph of the NCRA/CHS Refinery, showing large above ground storage tanks, the processing area, and a pond. McPherson, Kansas, is in the background.

An aerial photograph of the NCRA/CHS Refinery. McPherson, Kansas, is in the background.

The National Cooperative Refinery Association (NCRA), now known as and further referenced in this text as CHS, is an operating petroleum refinery (Refinery) located at 2000 South Main Street, McPherson, Kansas. The Refinery includes 1,300 acres of which 460 acres are restricted access. Refinery operations began in 1933 running 24 hours per day, 7 days a week. CHS processes approximately 100,000 barrels (420,000 gallons) of crude oil per day, except for when the Refinery is shut down for periodic repair, maintenance, and/or installation of new equipment. Crude oil is supplied to the Refinery mostly through pipelines. However, a small quantity of oil products is delivered by truck. Products produced include consumer and commercial-grade fuels and various petrochemical feedstocks such as propane, fertilizer, and coke.

The main Refinery process areas consist of a product tank farm, product pipelines, a truck loading facility, warehouses, laboratory, maintenance offices and shops, a waste water treatment facility, and the Refinery's administrative headquarters. Most of the process units and equipment within the main process area are situated over concrete slabs with perimeter curbs. The remaining portions of the process area are paved and/or covered with gravel.

Land use immediately adjacent to and surrounding the Refinery is mostly agricultural. The nearest residential areas are approximately half a mile to the south. These properties are generally located upgradient with respect to the local groundwater flow. It is important to note however, that there are Refinery production wells and groundwater containment and light non-aqueous phase liquid (LNAPL) wells that artificially influence and/or control the groundwater flow.

In December 2000 CHS (then NCRA) signed a Consent Order (CO) with KDHE, and subsequently completed a Comprehensive Investigation and Corrective Action Study (CI/CAS). A subsequent Consent Agreement and Final Order (CAFO) Amendment was signed December 12, 2012. This Amendment replaces the groundwater containment Settlement Agreement (1988) and the original 2000 Consent Order; incorporates investigation and interim corrective action requirements for the El Paso Former McPherson Terminal Site; and includes developing planning documents for completing a Corrective Action Plan (CAP) and for conducting Corrective Action at the combined Refinery and former El Paso properties.

The El Paso Former Terminal Additional is located at the south end of the Refinery site. The terminal site property was purchased by CHS in 2013. Investigation and remediation work were completed at the El Paso Former Terminal while El Paso still owned it, and included both groundwater monitoring and use of a pilot-scale soil vapor extraction system. An Interim Corrective Action Decision (CAD) was issued by KDHE for the former terminal site in April 2013 that required ongoing groundwater containment and LNAPL skimming. Ongoing monitoring and any future remediation responsibilities were incorporated into the Amended CHS CAFO after the CHS assumed ownership.

Underground Oil Recovery Progam (UGOR)

Groundwater flow in and around the Refinery is extremely complex and is in part the result of natural hydrogeologic complexities. Groundwater flow is further complicated by operation of water supply wells in and around the Refinery main process area. Since early 2004, in response to a chloride plume encroaching upon and threatening refinery process waters, CHS has also operated a groundwater interception, recovery, and disposal system east of the Refinery. The operation of the water supply and chloride recovery wells influence local groundwater conditions.

The UGOR Program began in 1987. CHS has recovered nearly 217,270 barrels (9,125,340 gallons) of LNAPL from the top of the Equus Beds aquifer. The LNAPL is reintroduced into the refining process while the separated water is then treated at the Refinery waste-water treatment plant (WWTP). The amount of LNAPL recovered has significantly decreased since 2008 and the UGOR Program has gone from continuous pumping to monthly "slurping" of selected wells. Approximately 1,160 gallons of LNAPL are currently recovered each year.

As part of UGOR performance monitoring, CHS conducts routine groundwater sampling and analysis and provides KDHE with annual performance monitoring reports. These UGOR reports show that the program wells are routinely non-detect for customary refinery contaminants (benzene, toluene, ethylbenzene, total xylenes (BTEX); meth tertiary butyl ether (MTBE); naphthalene; and other petroleum-related chemicals). These performance monitoring reports also show that the UGOR system is maintaining adequate petroleum-product and groundwater containment.

In summary, the CHS Refinery groundwater monitoring program verifies the extent of LNAPL and the performance of LNAPL recovery efforts. The program also assesses groundwater quality at the former El Paso Terminal facility and the CHS Refinery perimeter zero-line wells. Annual reports summarizing the groundwater monitoring data are maintainted in the KDHE Administrative File.

Previous Investigations

A RCRA facility assessment (RFA) was conducted in 1987 in which several solid waste management units (SWMU) and areas of concern (AOC) were first identified. Phase assessment of these areas was conducted as part of the original CO and 2012 CAFO amendment. These phased activities include:

  1. Comprehensive Investigation (multiple documents)
  2. Risk-Based Screening Evaluation (RBSE)
  3. Data Gaps Sampling Program
  4. Ecological Risk Assessment (ERA)
  5. Human Health Risk Assessment (HHRA)
  6. Vapor Intrusion Evaluation
  7. North Area Soil Investigation
  8. added characterization of Exposure Area (EA) 08.

Investigation findings include:

  • The primary constituents of concern for the Refinery included volatile organic compounds (VOCs); semi-volatile organic compounds (SVOCs), primarily polycyclic aromatic hydrocarbons (PAHs); total petroleum hydrocarbons-gasoline range organics (TPH-GRO); total petroleum hydrocarbons-diesel range organics (TPH-DRO); cyanide (surface water only); and metals (primarily arsenic and lead) in soil and sediment.
  • Various soil sample locations and depths noted free-phase hydrocarbons, hydrocarbon odors, and black staining. LNAPL is also pervasive in groundwater.
  • Lead and arsenic were the only inorganic constituents detected in soil and sediment samples above Risk-based Standards for Kansas (RSK) (see RSK Manual - 5th Version (October 2010, revised March 2014 and September 2015)). The majority of the arsenic RSK exceedances are associated with RSK Tier 2, soil to-groundwater protection pathway screening values (5.84 mg/kg) set in the 2003 version of the RSK Manual.
    Please note that KDHE's 2003 version of the RSK Manual included soil-to-groundwater values for selected inorganic parameters, arsenic included. KDHE however rescinded all soil-to-groundwater standards for [heavy] metals in the 2007 version of the RSK Manual. Thus, the soil-to-groundwater values cited in the Final CAS are included to support the conclusion that there is little cross-contamination risk associated with arsenic.
  • Arsenic was detected above the direct contact (soil) exposure pathway RSK (38 mg/kg) in 2 of 746 soil and sediment samples. However, arsenic was also detected in 19 of the 20 samples collected from background boring locations. These background detections were above the soil-to-ground water protection pathway RSK in three samples.
  • Sulfide [reactive] was detected in samples collected from Bull Creek (please note that RSK values have not been established for reactive sulfide). This parameter is typically used to determine if a waste material is considered hazardous according to RCRA waste reactivity characteristics.
  • Total chromium, lead, nickel, and total cyanide were detected at various locations in Bull Creek. These exceedances of the surface water quality standards were observed both upstream and downstream of discharge points from the Refinery and are not conclusive as to the source(s) of the constituents.
  • The groundwater quality monitoring system surrounding the Refinery consists of nine "zero-line" wells screened in the upper portion of the Equus Beds. Groundwater samples from these zero-line wells are collected on a quarterly basis and analyzed for parameters customarily associated with petroleum refining operations, namely VOCs. BTEX was detected in Zero-Line well ZL-3. These detections were attributed to the closed El Paso Terminal located southeast and hydraulically upgradient of well ZL-3. Trace levels of other VOCs in well ZL-1 were detected; however, these detections are below the RSK groundwater screening value.
  • As part of the Clean-Fuels Project construction activities in and around several of the AOCs and SWMUS, contaminated soil was removed from affected areas and handled per the Soil Waste Management Plan (SWMP). These construction activities function as interim removal actions.
  • Initial Hazardous Waste Land Farm (HWLF) groundwater monitoring results note statistically significant levels of petroleum hydrocarbons in the groundwater. However, a Groundwater Demonstration Report concluded that past operations at the adjacent Former El Paso Terminal facility likely released petroleum hydrocarbons to the environment. The report further concluded that BTEX compounds and various metals detected in HWLF monitoring wells likely migrated from the Former El Paso Terminal facility.

Interim Corrective Actions

Various interim corrective actions have been implemented at the Refinery since 1987. These interim corrective actions include:

  • Hydraulic containment of LNAPL and impacted groundwater
  • Recovery of petroleum LNAPL
  • Removal of impacted soils and on-Site treatment (landfarming) and/or off-Site disposal (i.e. during Clean-Fuels Project construction and other general infrastructure construction projects)
  • Removal of waste and debris and off-Site disposal
  • Construction of barriers (i.e., building foundations, or concrete or asphalt pavement) between impacted media and potential receptors

Human Health Risk Assessment (HHRA)

The HHRA was prepared following the Risk Assessment Work Plan and after EPA and KDHE reviewed and approved exposure scenarios, site-specific exposure assumptions, and risk assessment calculation methods. Potential receptors included: site workers, utility workers, construction workers, and recreational users.

Chemicals of [Potential] Concern (COPCs) include:

  • arsenic, lead, carcinogenic PAHs, and petroleum mixtures (Soil Direct Contact Pathway)
  • selenium, PAHs, and petroleum mixtures (Soil to Groundwater Protection Pathway)
  • BTEX and naphthalene, based on soil vapor data (Soil Vapor Pathway - for example, vapor intrusion while trenching/excavation)
  • A limited list of metals, VOCs, or PAHs depending on the water body (Surface water)
  • Metals, PAHs, VOCs, and petroleum mixtures for selected SWMUs (Sediment). The COPC list for sediment was based on positive detections of COPCs, since this medium was not subjected to quantitative screening.

Potential vapor intrusion pathways for the Refinery were evaluated to supplement the HHRA. An Addendum to the HHRA Report (ERM, 2016) was prepared consistent that presented the vapor intrusion pathway evaluation. The conclusions presented in the Vapor Intrusion Addendum for the Refinery HHRA Report include:

  • The petroleum vapor intrusion (PVI) exposure pathway has been evaluated for the Refinery and does not pose excess risk or hazard for the full-time indoor workers at the Refinery given current conditions.
  • Due to the uncertainty inherent in forecasting future conditions, qualitative and quantitative data were evaluated for a future scenario. PVI into a hypothetical building without engineering control is not anticipated to be a concern for most Refinery areas.

Hazardous Waste Land Farm (HWLF)

As documented in the updated Post-Closure Plan the HWLF operated under interim closure status from June 1986 until closure in on June 19, 1990. No wastes were added to the HWLF after initiating closure and post-closure activities. The HWLF closure report was accepted by KDHE on October 8, 1990, and is included in the Administrative File. Assuming a 30-year performance period, the post-closure period was anticipated to terminate in October 2020. However, in November 2018 KDHE proposed and CHS accepted the transfer of Post-Closure Care and HWLF groundwater monitoring oversight from the KDHE, Bureau of Waste Management (BWM) to the Bureau of Environmental Remediation (BER) while also allowing the post-Closure period to terminate.

HWLF groundwater monitoring wells were sampled semiannually from October 1992 until October 1995, then quarterly from April 1996 through December 2010. With KDHE approval, the HWLF groundwater has been monitored semiannually since January 2011.

The HWLF will remain under cover of the concrete heat exchanger bundle cleaning slab for the life of the slab. This will prevent [potential] exposure to wastes remaining in the soil. CHS acknowledges that hazardous wastes are generated and stored at this slab and this may constitute a new SWMU for the Refinery. Therefore, the operation, maintenance, and post-closure care procedures to be implemented for the concrete heat exchanger bundle cleaning slab will be presented in the Refinery CAP.

Corrective Action Goals (CAGs)

Final cleanup goals for unrestricted future use and site closure consists of Federally established Maximum Contaminant Levels (MCLs) and/or Kansas Department of Health and Environment RSKs for residential groundwater. However, Alternate Treatment Goals (ATGs) for groundwater may be established as part of the Refinery Corrective Action Plan.

The majority of the TPH data in the CAS Report is reported as TPH-GRO and TPH-DRO. However, in September 2015 KDHE issued a new policy addressing the characterization, remediation, and management of TPH-impacted sites (Policy No. BER-041). The policy introduced new parameters for measurement of TPH including Low-Range Hydrocarbons (LRH), Medium-Range Hydrocarbons (MRH), and High-Range Hydrocarbons (HRH). Corrective action activities at the Refinery involving TPH-impacted media will utilize Policy No. BER-041 for establishment of cleanup standards as applicable.

CAGs were developed and approved during the January 2017 meeting between project stake holders. They include:

  • Prevent human exposure to site-related COCs in soil, groundwater, and indoor air in buildings intended for occupancy that were identified as posing an unacceptable risk in the HHRA and Vapor Intrusion Addendum
  • Minimize the potential for additional degradation of groundwater
  • Prevent dissolved phase COCs in groundwater and LNAPL from migrating beyond the facility boundary. MCLs or KDHE RSKs for residential groundwater will be the final cleanup goal for unrestricted site closure; however, ATGs to help focus, prioritize, and sequence remedial actions at the site may be established as part of the Refinery CAP in consultation with KDHE.
  • Recover LNAPL to the extent practical
  • Manage impacted media on the facility during future ground disturbance activities

A significant modification in performing RCRA Corrective Actions was announced by the EPA, in which a stream-lined approach to performing Corrective Actions action was presented; it is called the RCRA Facilities Investigation Remedy Selection Track, or RCRA FIRST process.

The RCRA FIRST process ensures selection of a remedy that is both practical and protective of human health and the environmental, while accelerating progress towards satisfaction of Government Performance and Results Act 2020 project milestone goals. More specifically, a Remedy Selection Meeting replaces the need for a robust, wide-ranging analysis of remedial technologies and alternatives in the CAS. After this meeting, CHS prepared the Focused CAS which serves as a summary of the Remedy Selection Meeting and evaluates the proposed corrective measures against the applicable screening criteria specified in Federal and State guidance. By taking this approach, CHS satisfies the State requirements for a CAS, while stream-lining the overall remedy selection process.

As discussed during the January 2017 meeting KDHE and CHS agreed that based on the operational nature of the Refinery a formal evaluation of all potential remedial alternatives would not benefit the overall path forward. The recommended corrective actions for the McPherson Refinery include:

  • Continue focused LNAPL recovery throughout Refinery based on thickness, transmissivity and suitable geology;
  • Monitor hydrocarbon and LNAPL degradation by completing the sampling, analysis, and calculations needed to estimate the rate of Natural Source-Zone Depletion (NSZD) in the groundwater and vadose zone
  • Continue groundwater pumping in conjunction with Refinery water supply uses to maintain hydraulic control of LNAPL and dissolved constituents and development of a groundwater Receptor Management Plan to monitor groundwater usage beyond the Refinery boundaries
  • Maintain institutional controls to prevent consumptive use of groundwater on Refinery property and to prevent land use inconsistent with the remaining impacted media
  • Complete the investigation and, as necessary, soil removal actions identified in the HHRA and during Refinery construction activities
  • Where excavation cannot be completed, cap impacted soil with clean soil, structures, concrete, or asphalt to prevent exposure
  • Complete excavation, soil management, or spill response activities in such a way as to prevent worker exposure to impacted soils through notification procedures, engineering controls, and implementation of the Refinery SWMP and associated Refinery health and safety procedures
  • Evaluate and, if determined applicable, design and maintain engineering controls in occupied permanent buildings located above impacted soil and/or LNAPL to prevent exposure to vapor-phase hydrocarbons
  • Continue the implementation of process controls, preventative maintenance, Refinery upgrades, and response protocols to prevent and respond to spills/releases
  • Evaluate potential implementation of methods which could cost-effectively and significantly increase the rate of dissolved-phase and/or vadose zone NSZD
  • Modify the existing Environmental Use Control Agreement (EUCA) for the former El Paso Terminal area by incorporating the Refinery-wide property into a single EUCA.

The Draft CAD presents KDHE's preferred alternative for the Site. However, KDHE may modify this alternative or select another response action based on new information or public comments. KDHE will select a final remedy for the Site after reviewing and considering information submitted during the 45-day public comment period that ran from October 1, 2019 through November 15, 2019.

Additional Information

For additional information, please contact:

  • John Cook, KDHE-BER Project Manager, 785-296-8986

Site Documents