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In 2009, the City of Hutchinson’s Reverse Osmosis (RO) Water Treatment Plant Project was implemented and provided a regional solution to a groundwater contamination problem in the City’s southeast industrial area. The project also resulted in an economically beneficial and environmentally sound approach to cleaning groundwater contaminated with volatile organic compounds (VOC’s) and elevated chloride concentrations. The RO treatment facility provided a beneficial reuse of water by blending existing potable groundwater sources with treated, remediated groundwater. Since the project inception, groundwater remediation has successfully progressed and the City water users have received higher quality potable water through the City’s public water supply system.
It was determined early in the project that one of the City’s remediation wells used for containment and withdrawal of contaminated groundwater was impacted with biological fouling that contributed to biofilm buildup and treatment challenges at the RO water treatment facility. The remediation well, identified as RW-4, provided critical containment of the VOC contaminant plume and was required to pump continuously at a capacity of 1,000 gallons per minute to prevent further downgradient migration of contamination. Various treatment methods were attempted to eliminate the biofouling at the RW-4 remediation well, but none provided long term success. As a result, treatment of the bio-fouled water at the water plant contributed to increased chemical use and cost for pretreatment, higher feedwater pressures, fouling of pressure filter media, high filter backwashing frequencies with increased backwash water use, greater wear and tear on pumping equipment, increased wear on RO membranes, greater frequency of RO membrane chemical cleaning events, and increased energy costs.
Early in the life of the contamination remediation project, the City was approached by the owner of the property upon which the Remediation Well RW-4 is located, about the possibility of utilizing water from the well for crop irrigation. Although sprinkler irrigation may have been a viable option for VOC contaminant removal, it was determined at the time of the initial consideration that the chloride concentrations were excessive for crop irrigation and at risk of increase. After years of close water quality monitoring and observed decreases in both VOC and chloride concentrations, the possibility of utilizing the water for irrigation use and using spray irrigation as a VOC removal method was revisited. Upon research of a similar project done in Nebraska, it was determined that VOC removal through sprinkler irrigation was achievable. In addition to providing an additional treatment method, implementation of a sprinkler irrigation system would be economically beneficial to both the Landowner’s agricultural crop yields and the City’s treatment plant operations.
Agreements were reached between the City and the Landowner that would allow the City to provide water from the existing RW-4 Remediation Well to its agricultural partner for crop irrigation purposes. The necessary water appropriation permitting steps were taken with the Division of Water Resources and Groundwater Management District No. 2, along with modifications to the authorized remedial plan by the Kansas Department of Health (KDHE) and the USEPA.
The alternative remediation project received final authorization from KDHE and USEPA in Spring 2017. The irrigation equipment was installed by the Landowner in June 2017, along with minor well equipment modifications by the City. Upon completion of the system installation, performance testing was conducted by the City and concluded that the sprinkler irrigation system was successful in removing VOC contamination. The remediation well was equipped with automated flow transfer equipment that allows the water flow going to the City’s RO treatment plant, to be seamlessly transferred to the Landowner’s irrigation system without shutting off the pumping well. Upon stoppage of irrigation operations by the Landowner, the flow of water automatically returns to the City treatment plant, again without stopping the pump. The automated system provides uninterrupted operation of the RW-4 containment well, and a successful remedial alternative used in conjunction with the City’s RO treatment and air stripping process.
The project has provided both an innovative remedial alternative for VOC contaminant removal, and a Municipal and Agricultural partnership success story. The cooperative project is a successful example of water reclamation and beneficial reuse, and provides a win-win solution for Agri-Municipal interests.