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Private Wells

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Environmental Services

MassDOT Highway works closely with the property owner when assessing a private well for potential salt contamination. The DEP recommended guideline for sodium concentrations in drinking water supplies is 20 milligrams per liter (mg/l), and the secondary maximum contaminant level (MCL) for chloride is 250 mg/l. These recommended contaminant levels are referenced in DEP's Private Well Guidelines. The guideline for sodium is intended to be protective of individuals on a 1,000 milligram per day (mg/d) sodium-restricted diet, while the chloride MCL is an aesthetic value solely for taste. Investigations are performed in accordance with Standard Operating Procedures (SOP) pertaining to salt contamination complaints.

The Water Supply Salt Contamination Complaint Policy specifies that MassDOT Highway will perform an investigation of a private water supply well in the event that:

  • A resident is on a documented sodium restricted diet of less than 1,000 mg/d and the sodium concentration in the water supply exceeds 20 mg/l, or;
  • A resident is on a documented sodium restricted diet of less than 2,000 mg/d and the sodium concentration in the water supply exceeds 40 mg/l, or;
  • The chloride concentration in a domestic supply well exceeds 250 mg/l.

Property owners interested in the Salt Remediation Program should provide a written request addressed to the appropriate District Highway Director. The written request must include a copy of recent laboratory analytical results for salt constituents and coliform bacteria, a Private Well Data Form and Right of Entry. The homeowner is required to submit the water sample for analysis by a DEP certified laboratory. DEP certified laboratories for analysis of salt constituents and coliform bacteria can be located by referencing the DEP's website. After receipt of the necessary forms and the copy of the recent analytical report, MassDOT Highway's Environmental Services Section coordinates with the property owner to perform a site inspection of the property and domestic water supply. MassDOT Highway will also initiate the monthly sampling portion of the program during the initial site visit. Bottled water may be provided as an interim measure for eligible residents, provided certain criteria are met.

At the conclusion of the investigation, MassDOT Highway will make a determination on the appropriate course of action based on site information and laboratory analytical data.

These actions may include:

  • Construction of a replacement well
  • Connection to a public water supply when it's a cost effective alternative
  • Installation of a water treatment system
  • Denial of the salt complaint
  • Highway drainage modifications or improvements
  • Designation of a reduced salt zone (typically reserved for Municipal Water Supplies)

Salt Program coordinators have developed a comprehensive database which is utilized to track the progress of each salt complaint through the various stages (i.e., from initial complaint to completion), tracks well replacement priorities and summarizes the laboratory analytical data for each complainant. Upon completion of a well replacement, MassDOT Highway compiles a package for submission to the homeowner, which includes information on the well construction, analytical data, existing well decommissioning, applicable warranties, etc.

For an additional overview of the Program, please refer to the Salt Remediation Information Sheet.

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