As of June 2020, the temporary water treatment facility is online and capable of producing water at full designed capacity. The facility, located near the intersection of Valley Creek Road and Tower Drive, is treating water from four wells to meet water quality standards and guidelines for per- and polyfluoroalkyl substances (PFAS) using granular activated carbon.
Activated carbon is commonly used to adsorb natural organic compounds, taste and odor compounds, and synthetic organic chemicals in drinking water treatment systems. Adsorption is both the physical and chemical process of accumulating a substance, such as PFAS, at the interface between liquid and solids phases. Activated carbon is an effective adsorbent because it is a highly porous material and provides a large surface area to which contaminants may adsorb. Activated carbon is made from organic materials with high carbon contents such as wood, lignite, and coal; and is often used in granular form called granular activated carbon (GAC).
GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed. GAC can be 100 percent effective for a period of time, depending on the type of carbon used, the depth of the bed of carbon, flow rate of the water, the specific PFAS you need to remove, temperature, and the degree and type of organic matter as well as other contaminants, or constituents, in the water.
The temporary water treatment facility is expected to be in operation until a long-term water treatment solution can be implemented in the next five to seven years. Funds for the long-term solution are expected to be available from the $720 million settlement the state received from 3M in 2018.
The temporary water treatment plant, which typically takes about 18 months to two years to construct, was completed in about five months. In order to meet peak summer demand, it was critical the temporary treatment facility was operational as quickly as possible. The city would not be operating the facility today without the work and cooperation of the State of Minnesota, 3M, the City Council, numerous city staff, our engineering consultant teams, and the construction expertise of the project contractor.
At its Jan. 8, 2020, meeting, the Woodbury City Council took actions to expedite the construction of a temporary water treatment facility to treat three of the city’s six water wells currently exceeding water quality standards and guidelines for per- and polyfluoroalkyl substances (PFAS). On Feb. 3, the Minnesota Department of Health gave verbal notification that a seventh well exceeded the health-based guidelines for PFAS and this well was immediately removed from service (official notice was received Feb. 21).
Learn more about PFAS in Woodbury
The temporary water treatment facility has been constructed on the northeast corner of Tower Drive and Valley Creek Road over the existing parking lot. This parcel of property has been identified in the City’s current and past comprehensive plans as a site for a future water treatment facility. 3M and the State of Minnesota are funding construction of the temporary water treatment facility. View the site plan.
The temporary treatment facility measures approximately 9,500 square feet to meet the treatment needs for four of the impacted wells. A new watermain was also constructed to connect Well 17 to the facility.
Learn more about long-term solutions on the 3M Settlement Website
Impacts on the Tamarack Nature Preserve
Protection of the existing park area, trees, and trail network were critical factors in locating the facility within the existing parking lot. Access to the park and trail network will be disturbed during construction but will be replaced. Replacement is expected by the end of summer 2020.
The parking needs for the trail network, park and adjacent preserve are being relocated to provide better access to the preserve amenities. The site plan includes 10 parking spaces, and street parking will remain available as an option for visitors. An additional 10 parking spaces could be made available should more parking needs be identified in the future.
To the east of the facility, within the circular driveway, a stormwater pond will be constructed to improve site stormwater management which is currently limited. With the addition of the stormwater pond, the site will meet the stormwater management requirements of the City and Ramsey-Washington Metro Watershed District.
Approximately 40 trees have been removed to facilitate construction of the temporary water treatment facility. A tree replacement plan will be created which meets the replacement ordinance. Eleven of these trees are Ash trees, which would be removed in the future under the City’s response to the Emerald Ash Borer (EAB).
Questions about this project can be directed to Utilities Manager Jim Westerman at firstname.lastname@example.org or 651-714-3720.