Benzene Treatment System at Porter Wells

Rollinsford, New Hampshire

Client: Rollinsford Water & Sewer District


  • Construction Administration
  • Drinking Water Treatment (Benzene)
  • Hydraulic Design
  • Permitting
  • Process Design

Project Summary

Hoyle, Tanner completed design, permitting and construction administration services for this water treatment project at the Porter Wells site in Rollinsford. This was an extension of a previous project in which one of the two wells at the Porter Well was replaced, using funding under the American Recovery and Reinvestment Act (ARRA) of 2009. Water quality testing of the new well revealed that the raw water contained benzene at 40 times the EPA allowable concentration limit of 5 parts/billion (ppb).

The New Hampshire Department of Environmental Services (NHDES) was not going to allow the District to use the new well, a critically needed water supply with a high yield, due to concerns over the benzene concentrations in the raw water. Hoyle, Tanner convinced the NHDES that the benzene could be easily and readily treated to meet safe drinking water limits thereby preserving a productive, high-yield, critically needed water supply and was allowed to proceed with design and implementation of the benzene treatment system.

Working closely with the District staff, a low-profile, aeration-based treatment system was selected that fit into the existing arsenic treatment building. The control system for the new benzene treatment system was fully integrated with the control system for the arsenic treatment system and the well pumps for the two wells. The benzene treatment system is successfully reducing the benzene concentration to well below the EPA-allowable Maximum Contaminant Level (MCL) of 5 parts per billion (ppb). Although the new well is presently only permitted for a maximum volume of 57,559 gallons/24-hour period, it has a demonstrated yield of over 200 gallons/minute thereby providing the District with a valuable water supply source for the future.

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