DO DRINK: Providing Potable Water for a Small Groundwater System

Authors:

  • Marc Santos, Julie Herzner, and William Becker – Hazen and Sawyer
  • Dan Despard – Savin Engineers
  • Jerry Gilnack and Bridget Barclay – Dutchess County Water and Wastewater Authority

The Shore Haven Water System provides chlorinated groundwater for a small community in Holmes, NY. In 2005, the Shore Haven Water System received a “DO NOT DRINK” Order due to levels of disinfection byproducts (DBPs) that consistently exceeded the federally established drinking water standards. Additionally, historical water quality data for the system has shown high concentrations of iron (Fe) and manganese (Mn) and occasional radionuclide concentrations above the maximum contaminant levels (MCLs).

The design team developed a phased approach to (1) implement a temporary solution to lift the “DO NOT DRINK” Order issued by the New York State Department of Health and (2) design a permanent treatment system to address the multiple drinking water contaminants present in the Shore Haven water system. To identify the sources and precursors responsible for the contaminants, an evaluation of the water quality data, sampling program, and operating procedures was performed. Results identified low levels of total organic carbon (2-3mg/L) in the Shore Haven groundwater water supply; however, uncharacteristically high concentrations of post-chlorination DBPs were observed throughout the distribution system. Preliminary bench-scale testing with granular activated carbon media revealed that breakthrough times for Shore Haven water were prohibitively short (weeks) compared to those of typical groundwaters (usually on the order of several months). In addition to the irregular water quality, system constraints included the lack of an on-site sanitary sewer, close proximity to community homes, accelerated timeline, and budget constraints.

The short-term operational change employed to lift the “DO NOT DRINK” Order utilized a newly drilled well (Well No. 3) with lower DBP formation potential than the two wells previously in service. As a preventative measure, a standby chloramination system was installed to replace chlorination if DBP formation potential of Well No. 3 increased. In parallel with the installation of the temporary chloramination system, the design team completed a comprehensive review of available treatment technologies for the permanent treatment system. Technologies were compared by evaluating key criteria including: contaminant removal efficiency, system cost, system footprint, and waste production. The final proposed treatment train included a MIEX® system for reduction of organic carbon (DBP precursors), which showed up to 67% reduction of dissolved organic carbon during bench-scale testing. The primary technology selected for Fe, Mn, and radionuclide treatment was tested in a pilot-scale study to validate treatment efficiencies for the unique groundwater.

This paper will discuss the fast-track treatment approaches implemented to lift the “DO NOT DRINK” Order and will present the permanent treatment train selection process performed for a small community’s water system.

For more information, please contact the author at msantos@hazenandsawyer.com.

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