FMGP - Pittsburg
Former Manufactured Gas Plant Site
Several Site investigations characterizing the nature and extent of Site-related impacts were conducted in 2014, 2015, 2019, and 2020. The Site investigation results are summarized in the Final Comprehensive investigation (CI) Report (Black and Veatch, 2020). Investigation fieldwork included collecting 56 soil samples and installing four groundwater monitoring wells. With two exceptions, all samples were submitted for typical FMGP contaminant analysis including: polynuclear aromatic hydrocarbons (PAHs); benzene, toluene, ethylbenzene, and total xylenes (BTEXs); metals (arsenic, barium, cadmium, chromium, and lead); and cyanide.
The Risk-Based Standards for Kansas, RSK Manual, 6th Version, July 2021) (RSK) non-residential screening levels are generally based on potential industrial/commercial exposure. These potential routes of exposure are associated with contact with surface soil during outdoor maintenance activities such as digging and landscaping. Subsurface soil is the primary exposure medium since most of the Site (and surrounding properties) is paved and/or covered with grass or gravel. This type of exposure is typically represented by a construction or utility worker scenario for which the RSK is not directly applicable. Since RSK values have not been developed for the construction worker scenario and to help in the development of a reasonably conservative assessment of Site-related risk, the U.S. Environmental Protection Agency (EPA) construction worker regional screening levels, (RSL) were developed. The EPA construction worker RSLs are considered more representative of likely exposure that would occur in the alley during typical [subsurface] utility work.
Shallow soil samples (between 2 and 2.5 feet below ground surface) were collected from both hand-augured and direct-push probes. No BTEXs concentrations were detected in any of the shallow soil samples. The highest on-Site PAH detections are in samples from probes SP-01, SP-05, SP-11, and SP-12 which contained multiple PAH detections above 1,000 mg/kg. Samples from 11 of 18 probes exceeded the EPA construction worker RSL. Samples from 15 of 18 probes exceeded the KDHE RSK (non-residential) screening value.
PAH concentrations for off-Site and alley-way samples decreased substantially compared to concentrations in samples collected from on-site concentrations. Benzo(a)pyrene exceed the non-residential RSK in seven samples and the EPA construction worker RSL in one sample. No lead, arsenic or cyanide concentrations exceed the non-residential RSK values (1000 mg/kg, 63.2 mg/kg, and 1230 mg/kg respectively).
The EPA composite worker limit for arsenic (3.0 mg/kg) is exceeded in all samples, but only the soil samples from on-Site probes MW-01 and SP-12 and offsite probe SP-28 exceed the construction worker RSL for arsenic (23.7 mg/kg). In general lead concentrations exceeded the RSK residential value (400 mg/kg) in shallow soil samples collected from on-site or the alley way locations. The highest lead concentration reported from these shallow-soil samples is 847 mg/kg. Finally, cyanide was not detected in any soil samples above regulatory values.
Deep soil samples (generally no deeper than eight feet below ground surface) were only collected from direct-push probes. The following is a brief comparison of the deeper soil data with the RSK and RSL: Consistent with the shallow soil samples, no BTEX constituents were detected.
All deep soil samples concentrations of PAH compounds contained lower PAH compounds, except for sporadic PAH detections in probes SP-04 and SP-09. Samples from 9 of 15 probes (MW-02, MW-04, SP-03, SP-04, SP-08, SP-09, SP-10, SP-11, SP-15) contained PAHs above the KDHE non-residential RSK. Samples from 7 of 15 probes (SP-03, SP-04, SP-08, SP-09, SP-10, MW-02, MW-04) exceeded the construction worker RSL.
Although arsenic, barium, cadmium, chromium, and lead were detected in the deep soil samples above analytical detection limits, no reported concentrations exceeded the RSK residential/non-residential screening values (EPA has not established lead RSLs for composite worker and construction worker exposure scenarios.) All cyanide detections were less than the residential/non-residential RSK values.
The concentrations of PAHs are substantially lower in the shallow subsurface soil samples collected from the alley when compared to samples collected at similar depths on-Site. In general, shallow on-Site soil samples have higher concentrations than deeper samples collected at the same location. On-Site concentrations exceeded KDHE non-residential RSK and EPA construction worker RSL. In the alley, sample SP-35 exceeded the EPA construction worker levels for PAHs. Because of the alley's gravel cover, the construction worker pathway is considered the most representative of potential exposure pathway. Arsenic concentrations do not exceed the non-residential RSK or the EPA construction worker RSL. According to the U.S. Geological Survey National Chemical Survey Database (Crawford County, Kansas – USGS 2008), all but two arsenic concentrations detected are within the average concentration range found in Crawford County, a historical lead mining region of Kansas.
Four groundwater monitoring wells, MW-01, MW-02, MW-03, and MW-04, were installed in 2014. Groundwater samples were initially collected in March 2014 from three of four wells (MW-04 did not produce a suitable quantity of groundwater for sample collection/analysis). The remaining samples from MW-01 through MW-03 were analyzed for BTEX, PAHs, metals, and cyanide. All wells were resampled in April 2014 for PAHs due to analytical laboratory contamination identified in the March 2014 samples. Samples collected in 2019 were analyzed for BTEXs, PAHs, arsenic, and lead.
Hydrologic data (i.e. depth to water) from 2014/2015 and 2019 support the conclusion that the Site aquifer recharges very slowly as a baseline condition; however, water levels were considerably higher in 2019. Also, due to the relatively flat groundwater surface, water levels do not provide reliable data for determining groundwater flow direction.
During fieldwork performed in 2014 an opening and vent pipe for an underground storage tank (UST) was observed north Lot 107 North. Discussions with the land owner note that the presumed Underground Storage Tank (UST) was on the property when it was purchased, and that its contents were unknown at the time of purchase. The depth to the base of the tank was six feet. Analytical laboratory data from the UST contents sample report that the tank liquid contained diesel fuel and gasoline range organics, but at concentrations less than regulatory levels.
Groundwater analytical results for samples collected in 2014 identified dibenzo(a,h)anthracene as exceeding KDHE non-residential RSK screening values in MW-02, MW-03, and MW-04. The analytical laboratory detection limit of this PAH exceeded the residential RSK in all wells, meaning that the reported values could be below the detection limit while exceeding the RSK resulting in potentially “false negative” data. It should be noted that RSK screening values are based in part on calculated risk ranges and may not currently be analytically achievable.
The 2014 concentrations of arsenic and lead also exceeded the residential RSK in MW-04. BTEX compounds were detected in well MW-01 but at concentrations less than the RSK residential screening values.
None of the groundwater samples collected in 2019 had PAH detections exceeding RSK screening values. Detection limits for dibenzo(a,h)anthracene continue to exceed both the residential and non-residential RSK. No BTEX compounds were detected in any well above RSK screening values, while arsenic was below the RSK. Lead was the only parameter detected above RSK screening values and historically was 2014.
The Evergy (formerly known as Western Resources, Inc.) Former Manufactured Gas Plant (FMGP) Site (Site) is located in the downtown area of Pittsburg (City), Kansas. The FMGP site occupies City lots 103, 105, and two discontiguous lots identified as “107”. Lot 107 for the purposes of this Draft Agency Decision Statement (ADS) is identified as “North 107” and “South 107”. The lots noted are bounded by East 2nd Street (to the north), North Locust Street (to the east), East 1st Street (to the south), and an alley way (to the west). A railroad line was formerly located north of the Site along the 2nd Street right-of-way; it was removed sometime after 1992.
The properties are owned by: R. E. Williams & S. F. Williams Rev Trust (Lot 103), which contains a corrugated metal building (Quonset hut) used for storage; T&K Rentals (Lot 105) includes a brick building associated with the former Kansas Gas and Electric operations which is currently used for storage; and, K. Linder (Lot 107 North) which includes a brick building that formerly housed Kansas Gas and Electric operations. Lot 107 South is owned by the City and includes a radio communications tower and a control shed.
The Site and surrounding properties are zoned commercial/industrial except the property directly to the south of East 1st Street, which is zoned residential. (Crawford County 2020).
The Pittsburg Gas & Electric Company operated the Manufactured Gas Plant (MGP) from approximately 1887 through 1905. Sanborn Fire Insurance Maps (Sanborn) of the property show over time typical but evolving MGP configurations and structures including: coal bins, a lime house, retorts, a gas holder, and a tar well (storing the coal-gas byproduct known as “coal tar”). The MGP is first identified on the 1892 Sanborn Map. According to Brown's Directory of American Gas Companies the MGP produced between 12 and 15 million cubic feet of coal gas per year.
After the MGP was closed (in 1905) buildings associated with gas manufacturing were razed and the electric power generation plant expanded. The MGP gas holder remained and was then used as a reservoir in connection with the electric plant operations. The electric plant operated between 1923 and 1944. In 1971 Kansas Gas and Electric sold the property to an armature works company. The property was transferred to a private individual in 1989.
Corrective Action Remedial Alternatives (more fully discussed in the Final CAS – Black and Veatch, (December 2020) consist of:
- Alternative 1 – No Action;
- Alternative 2 – Institutional Controls and Groundwater Monitoring;
- Alternative 3 -On-Site Excavation;
- Alternative 4 – Alley Surface Improvements (Capping);
- Alternative 5 – Alley Excavation.
The contaminants of concern are residual PAH compounds in subsurface soil, sporadic detections of one PAH compound and minor/ephemeral arsenic and lead in groundwater. Remedial action objectives include: 1) preventing and/or minimizing human exposure through direct contact with contaminated soil; and, 2) preventing and/or minimizing human exposure through ingestion of contaminated media.
On the basis of Administrative File information and the Final CAS, KDHE recommends selecting a combination of Remedial Alternatives 2 and 5 consisting of soil excavation (in the alleyway), placing institutional controls (Environmental Use Control) on the properties that comprise the original gas plant and the City of Pittsburg property (south of the original MGP property), and groundwater monitoring.
The recommended remedial response includes all previously completed investigations and/or response actions, and the pending Environmental Use Control which will be recorded with the Crawford County Register of Deeds. The recommended remedial response also includes a minimum of two years of semi-annual and up to three years of annual groundwater sampling. The groundwater performance monitoring would track concentration trends to assess whether residual contaminant levels continue to decrease and do not migrate off-Site at levels exceeding the RSK screening values.
Implementation of this remedial approach would meet the corrective action objectives of preventing residential development and controlling exposure to residual soil contamination. With the presence of the existing structures that comprise most of the properties, removal of soil around existing buildings would be difficult and would not address residual contamination below the structures. Based on the current non-residential use of the structures, the buildings function as a surface cap reducing contamination exposure risks.
A Public Information Plan for the Site was developed by KDHE and includes implementation criteria satisfying public participation requirements. Public notice of the availability of the Draft Agency Decision Statement (ADS) will be published in the print-edition of the Pittsburg Morning-Sun newspaper on April 2, 2022. The Draft ADS and other selected administrative file documentation will be available for review at the Pittsburg Public Library, 308 North Walnut, Pittsburg, Kansas 67410 from April 2, 2022 through April 19, 2022. All pertinent documents related to the Former Manufactured Gas Plant site are also available for review at the KDHE offices in Topeka, Kansas during this public comment period. To review documents in Topeka, please contact John K. Cook, PG at 785-296-8986. Public comments on the Draft ADS may be submitted to KDHE in writing during the 15-day public comment period at the address listed below.
Kansas Department of Health and Environment
Bureau of Environmental Remediation
1000 SW Jackson Street, Suite 410
Topeka, KS 66612
Contact – John K. Cook, Professional Geologist
Site Restoration Unit
Comments on the Draft ADS may also be submitted to KDHE by electronic mail to [email protected] Comments sent by electronic mail must be received by KDHE no later than 5:00 p.m. on September 17, 2019. Through this process, the public and other interested parties are given the requisite opportunity to provide input on the proposed corrective action strategy for the Site before the Agency Decision Statement is finalized.