Site Narrative:
Contamination at the site was first identified in June 2012 when a property owner noticed petroleum hydrocarbons in his irrigation well. Sample results showed the groundwater has been impacted with benzene, toluene, ethylbenzene, xylene, naphthalene, and total petroleum hydrocarbons – gasoline range organics above the applicable Maximum Contaminant Levels (MCL) for drinking water or KDHE Tier 2 Levels for Groundwater. More than 50 gallons of separate-phase hydrocarbons were pumped from the well in June and July 2012.
The irrigation well is located near a NuStar pipeline running through the area. NuStar performed hydrostatic testing of the pipeline and identified a release adjacent to and northwest of the impacted well. Excavation activities were conducted and a seep was identified. Significant soil impact in a 50-foot section was discovered, and impacted soil was excavated when the pipeline was repaired.
A Consent Agreement and Final Order (CAFO) has been negotiated between KDHE and NuStar for investigation and was executed on May 10, 2013. A Work Plan was submitted and approved by KDHE for investigation of the nature and extent of contamination. Implementation of the plan was initiated the week of July 22, 2013. In Oct. 2013, 16 monitoring wells were sampled along with 15 irrigation wells located within the area of investigation. The results were compiled and evaluated in the Comprehensive Investigation Report, approved by KDHE on May 7, 2014.
A soil vapor extraction pilot test was conducted the week of Dec. 9, 2013, to determine if this is a viable alternative to consider for remediation. A second neighborhood meeting was held on Feb. 17, 2014, to discuss the complete investigation results and possible alternatives for cleanup.
NuStar conducted additional soil investigation near the pipeline release area and submitted the results with an evaluation of excavation and a conceptual design in July 2014. A detailed excavation work plan was approved in August 2015. Excavation occurred in Oct. 2015. The Soil Excavation Report was approved in March 2016.
There have been two Groundwater Pilot Tests to evaluate groundwater remedial technology for treating the impacted groundwater. The initial phase of the pilot test was performed from March through June 2015. The expanded pilot test included the introduction of a more concentrated pelletized form of ORC Advanced and the installation of a larger number of injection borings to address residual dissolved-phase petroleum constituents in groundwater.
NuStar completed a Corrective Action Study that recommended corrective action alternatives for addressing the residual petroleum hydrocarbons in soil and groundwater. KDHE issued a Draft Corrective Action Decision which was available for public comment (May 2019). The Final CAD was issued in June 2019. The Corrective Action Plan for enhanced aerobic bioremediation was approved by KDHE in July 2020.
Groundwater is sampled semi-annually to assess the effectiveness of ongoing in-situ groundwater treatment and to monitor contamination.
The Home Owners Association installed through a licensed water well driller, an additional irrigation well (HOA 3) used for commons area lawn watering. That well, when recently sampled had detections of likely Site-related residual contaminants (primarily benzene) in excess of Kansas groundwater criteria. Therefore, with KDHE approval, the HOA took existing HOA 3 out of service and replaced it with a similar well in a location distant from likely residual sources.
Per a meeting held between KDHE and NuStar, a December 4, 2025 scheduling and task letter detailed actions necessary to determine the nature and extent of the possible new identified contamination. NuStar was found responsible for: 1) conducting an expanded round of groundwater sampling to delineate the horizontal and vertical extent of the contaminant plume; 2) completing additional site characterization to support a refined conceptual site model; and 3) coordination with the City of Andover to evaluate the feasibility of bringing a municipal waterline connection closer to the HOA 1 location. NuStar must assess options for providing an alternative water source for irrigation in the playground area and outline those options in documentation.
On January 22, 2026, the Irrigation Well Sample Results was received by KDHE and the Additional Site Characterization Work Plan was received by KDHE on March 4, 2026. The Irrigation Well Sample Results was approved on March 27, 2026.
On May 4, 2026, a Alternative Water Source Options Letter was received by KDHE with a comment letter sent May 7, 2026 requesting confirmation of tasks required for establishing the alternate source. Confirmation was received by Braun Intertec and Evergreen (NuStar) on June 6, 2026, establishing a acceptable source for the HOA-3 well. |