Cobble Mountain In-Line Hydropower
Cobble Mountain In-Line Hydropower

Project Background

The Commission currently has a power plant that was built in 1930 that utilizes the flow of water from Cobble Mountain Reservoir to the West Parish Filters Water Treatment Plant. The power plant is used to generate supplemental revenue to support other capital projects. The age of the power plant as well as changes in the energy market has led to the need for significant upgrades.

In recent years a feasibility analysis was conducted to assess whether in-pipe hydropower could be installed in conjunction with the need for a new 42" transmission main leading to West Parish Filters. The assessment determined the in-pipe system would be feasible and more cost-effective compared to upgrading the old plant.

Project Description

The proposed in-pipe hydropower system is a 2.0 Megawatt single Pelton-type turbine plant. The new plant will generate green power from the water pressure within the 42" transmission main, which is entirely gravity-fed. The power generated will used on-site at West Parish Filters to support new treatment upgrades there, and also sold back to the grid.

Expected benefits include increased energy efficiency and climate resiliency at West Parish Filters, renewal of end-of-life infrastructure, and generation of supplemental revenue. The approximately $14.7 million project is financed through low-interest loans from WIFIA and the Massachusetts Drinking Water State Revolving Fund.

The existing Cobble Mountain power plant, built in 1930.
Example of in-line hydropower generating system.