Sampling for wellhead protection uses a series of sentinel wells strategically located around the perimeter of the Mint Farm wellfield to establish a line of defense for advance warning of potential migration of contaminants from nearby industrial and commercial sources.

Diagram Showing Locations of Mint Farm Wells

Well Construction Reports

Deep Monitoring Wells Construction Report (PDF) - A detailed record of the geologic formation of deep monitoring wells DW-1 through DW-9 based on visual inspection of the cuttings produced during drilling and physical measurement made by instruments lowered into the hole.

Shallow Monitoring Well Construction Report (PDF) - A summary of the drilling activity for the construction of the first set of shallow monitoring wells. Provides the location, drillers well report, construction details and geologic log for wells SW-1 through SW-7.

Other Wellfield Reports

Mint Farm Wellfield Source Approval (PDF) (less appendices) - In accordance with Washington Administrative Code 246-290-139, this report was submitted to the Washington State Department of Health for regulatory approval of the Mint Farm wellfield. It summarizes the initial planning, engineering and hydrogeological evaluation, well logs and water quality information for each of the four production wells. 

Wellhead Protection Program (PDF) - The WHPP was developed to protect the groundwater source and comply with Washington Administrative Code 246-290-135 (3). The Department of Health approved the plan in March 2010 and it was incorporated in the City's 2012 Water Master Plan Update.

Water Supply Protection Ordinance Number 3209 (PDF) - This ordinance supplements the WHPP to minimize the risk of contamination and provide a means of enforcement, while still allowing economic development which does not pose unreasonable risk to the aquifer. Staff continues to work with Cowlitz and Columbia counties to adopt similar ordinances to protect the groundwater supply.