Nearman Creek Power Station Site


Site Background

The Nearman Creek Power Station (Site), a 235-megawatt, steam-turbine, coal-fired, electric generation plant (power plant), is owned and operated by the Kansas City, Kansas, Board of Public Utilities (BPU). The Site, located at 4240 North 55th Street, Kansas City, Kansas, Wyandotte County, occupies approximately 605 acres (Figure 1). It is approximately six miles upstream of the confluence of the Missouri and Kansas Rivers and is bounded on the north by the Missouri River and by the Union Pacific Railroad on the south and southwest sides. A railroad spur encircles the facility and is used to unload coal. The area west of the facility is flood plain while the area immediately east is agricultural land. The areas immediately north, east, and west of the Site are owned by BPU. There is currently a one-million gallon, above ground diesel storage tank (AST) on site. From 1980 to 1995 this AST was serviced by underground distribution lines that ran from the AST to the power plant. In 1995 the distribution line was abandoned in place and an above-ground distribution line constructed. Technicians discovered petroleum contamination in soils near the underground distribution line in 2013 during work to support an air quality improvement project.

An Environmental Agreement (EA) between KDHE and BPU was signed in April 2016. This EA requires BPU to conduct a Comprehensive Investigation and Corrective Action Study (CI/CAS) and obtain an Environmental Use Control Agreement (EUC). The primary CI/CAS objectives include: characterize groundwater flow beneath the area of release (i.e. the former diesel distribution line); assess groundwater quality downgradient of and between the area of release and municipal water supply wells; delineate and/or assess the extent of contaminants of concern (COCs) in groundwater; assess and present corrective action alternatives addressing environmental conditions; and, present recommendations for the most appropriate corrective action alternative.

Petroleum-related contaminants often associated with similar sites include: benzene, toluene, ethylbenzene and total xylenes (BTEX), methyl-tert-butyl-ether (MTBE), naphthalene, and total petroleum hydrocarbons (TPH) gasoline-range and diesel-range organics (GRO and DRO respectively). While TPH was initially reported as GRO and DRO, in 2015 KDHE changed the guidance to instead characterize petroleum contamination as low, medium and high-range hydrocarbons (LRH, MRH, and HRH respectively). The current standard is described in KDHE BER Policy, BER-041; Total Petroleum Hydrocarbons (TPH) and Light Non-Aqueous Phase Liquid (LNAPL) Characterization, Remediation, and Management.

Previous Investigations

Several environmental investigations and/or response actions focusing on petroleum-related parameters have been completed including a Limited Site Evaluation (LSE) in 2013, an Interim Measures (IM) removal action in 2015, and the CI/CAS in 2016/2017.

As a part of the LSE characterization, samples were collected along and immediately adjacent to the former underground diesel distribution line and other on-Site locations. Results from this investigation identified several contaminants in soil and groundwater, some of which exceed the corresponding Risk-based Standards for Kansas (RSK) values.

Additionally, during the 2013 LSE, TPH-GRO and TPH-DRO were identified in two groundwater samples. The maximum concentration from these samples, 2.9 milligrams per liter (mg/L) TPH-GRO and 684 mg/L TPH-DRO were above the then corresponding RSK, Tier 2, non-residential values (0.5 and 0.72 mg/L respectively).

In April 2015 BPU completed a voluntary IM (soil removal action) and submitted the Final Report for this activity to the Administrative File. The IM included nearly complete removal of impacted soil (impacts above RSKs values) and decommissioning of the southern portion of the former underground diesel distribution line. Roughly 781 tons of special waste were removed and transported to the Johnson County Landfill. The excavation was approximately 5 to 7 feet wide, 10 to 15 feet deep and 230 feet long.

Following removal, 37 confirmation soil samples were collected from along the side-walls and floor of the excavation and analyzed. Contamination levels in all confirmation samples were below applicable RSK, Tier 2, non-residential values, except for one soil sample collected from the floor of the excavation. This sample identified naphthalene at a concentration of 0.94 mg/kg which exceeds the RSK, Tier 2, non-residential soil to groundwater value of 0.659 mg/kg.

LSE investigation findings and field conditions observed during the IM noted possible non-aqueous phase liquid (NAPL) in groundwater at and/or surrounding the former release site. The impacted soil was removed resulting in no observable free hydrocarbons. No signs of NAPL were identified during the CI.

A groundwater monitoring well network was present at the Nearman Creek Power Station before the CI activities. Based upon previous gauging events of this pre-existing network, the direction of groundwater flow is generally to the north (towards the Missouri River); although there are season-based variations. Subsequent gauging confirms this general, seasonal trend.

Groundwater usage is limited in the immediate vicinity with the exceptions of two municipal supply wells. Groundwater quality from these wells is routinely monitored under the auspices BPU's Kansas and Federal National Pollutant Discharge Elimination System (NPDES) Permit: Kansas Permit Number I-MO25-PO10 and Federal Permit Number KS0095354.

During the CI 10 groundwater monitoring wells were sampled on a quarterly basis over a one-year period for TPH. While TPH-GRO and TPH-DRO in groundwater had been above RSK Tier 2 values in 2014, results of the quarterly groundwater monitoring events were all non-detects. The former impacts to groundwater do not extend beyond the former distribution line and are not threatening downgradient wells such as the municipal public water supply wells. Project documents support the conclusion that the groundwater contaminant plume is stable and/or attenuating over time and with distance from the former distribution line, and the interim removal action was effective at removing the source area thus minimizing future risk.

Receptors

Land use and receptors present in or around the Site are not expected to change from those present today. A perimeter security fence prevents access while security guards are present 24 hours a day, seven days a week. The power plant also has a series of closed-loop security cameras monitoring the Site. Only BPU employees, approved contractors, and known visitors are allowed access.

Workers present include employees and periodic construction and/or utility workers. Based on the current and expected future use, on-Site workers are the only reasonable direct-contact exposure scenarios. While groundwater samples collected from temporary piezometers have exceeded RSKs, the locations are now covered by a new operation unit that will remain in place into the foreseeable future. This impediment will prevent workers from accessing groundwater at these locations.

Remedial Actions

Remedial action objectives include: 1) preventing human exposure through direct contact with contaminated soil; 2) preventing human exposure through direct contact and/or ingestion of contaminated groundwater, and 3) restoring groundwater conditions to the extent practicable. The corrective action goals are meant to achieve KDHE RSKs for Residential and Non-Residential concentrations for soil and groundwater. Groundwater monitoring will continue until the Site is eligible for closure in accordance with KDHE Bureau of Environmental Remediation Policy, BER-RS-024, Site Closure in the State Cooperative Program.

If groundwater impacts directly related to the former diesel distribution line release are identified in the future, BPU has committed to address these concerns as a contingency action. Additionally, if the public water supply wells are threatened, KDHE retains the authority to re-open the remediation alternative decision and modify the remedy to ensure that the remedy remains protective of human health and the environment.

KDHE recommends selection of Remedial Alternative No. 2, which incorporates all previously completed actions as well as a commitment to contingency actions (if needed) and the recording of an Environmental Use Control which restricts future residential land use and prevents using on-Site groundwater as a public water supply. Selection of this remedial alternative will lead to "Conditional Closure." A summary of this corrective action alternative is provided in Section 6.1.2 of the CI/CAS Report linked below.

This alternative is protective of human health and the environment while being the most cost-effective response action. KDHE may modify this recommended selection in response to public comments received during the public comment period and/or if new information becomes available. Alternative 2 is readily implementable and provides a long-term means of preventing exposure to current use media and potential future use scenarios.

KDHE developed a Public Information Plan that included implementation criteria satisfying public participation requirements. A public comment period for the Draft Agency Decision Statement ended January 21, 2020.

Site Documents