Godfrey Brook Wellfield Restoration

Challenge

The Milford Water Company (MWC) required the restoration of a well field with de-clining yield. Five existing 12- to 10-inch diameter wells were underperforming due to partial plugging of the well screens due to fine sediment, iron, and manganese de-posits. The source water also exceeded the secondary limits for iron and manganese. The existing wells required rehabilitation to restore lost capacity, and new wells were required to restore the wellfield total capacity to the original permitted quantity.

Solution

GZA sub-contracted slip installation of new stainless steel well screens for two of the existing wells, and re-development by pumping and surging and compressed nitro-gen blasting of all existing wells. GZA oversaw a subsurface investigation program to prospect for well locations, and designed two new 12” x 18” wells which were con-structed by the subcontractor. GZA designed and executed two 24-hour pumping tests and developed a 3-dimensional numerical flow groundwater flow model using the MODFLOW code within the Aquaveo Groundwater Modelling System. The groundwater model was used to delineate the wellfield pumping area of influence under Massachusetts Zone II conditions (180 days of pumping with no recharge by precipitation). A Source Final Report was prepared and submitted to MassDEP in January 2021.

Benefit

GZA’s successful execution of the Godfrey Brook Wellfield Restoration project helps maintain the capacity of the wellfield, reducing the MWC’s reliance on other sources and ensuring delivery of high-quality finished water to their customers.