Cottage Grove had to shut down 8 of its 11 wells; good client-designer-contractor relations helped shrink a years-long solution to 2 months
I live in the land of 10,000 lakes. During the summer, Minnesotans’ activities revolve around water—swimming, fishing, boating, keeping our gardens and grass green—anything we can do to take advantage of the warm weather. Professionally, our team keeps a close eye on water regulations as they can change without notice.
All Minnesota water providers must meet the U.S. Environmental Protection Agency regulations for drinking water. In May 2017, the Minnesota Department of Health (MDH) issued new standards on two industrial chemicals that were stricter than the U.S. EPA. Because of these new standards, 8 of 11 wells in the City of Cottage Grove were forced to shut down until they could provide full compliance. Our team had to figure out how to complete a water treatment project that usually takes years—in just two months.
With the typical high demand for water during Minnesotan summers and the City having only 27% of wells available going into the summer months, there were ultimately two threats:
- A long-term sprinkling ban—many remember the drought of 1988 in Minnesota that ultimately led to a sprinkling ban and several types of vegetation never growing back.
- If the demand for water exceeded the ability to supply water with the diminished well capacity, then City staff would have to decide to pump the higher hazard index water or risk going too low on pressure and having to issue a boil order.
Complex process piping and valve assemblies were required for the treatment process to allow proper operation and future media exchanges.
Our mission was clear and the need was imminent: quickly identify and implement a solution to get two critical City wells back online in two months.
We worked with the City’s leadership to establish an interim solution to resolve the water quality concerns. Our interim solution gives us five years to develop a permanent solution. The interim plan involves blending water from various wells and treatment of water at critical wells. MDH identified a carbon filtration system as the approved treatment option.
Our team began design and construction on two of the wells just eight days after receiving news of the new standards. By June 1, we established a two-month turnaround for when the treated water would be available for delivery into the distribution system. This meant that design for excavations, footings/foundations, treatment vessels, process piping, plumbing, electrical and controls had to be conducted concurrently with initial construction efforts. We were impressed at how the contractors responded to the need for speed and were willing to work together in a cooperative manner.
The team communication was constant. Decisions were required daily, and field modifications were made as work was being completed to avoid delays. Upon completion of the piping system’s hydrostatic testing, we performed disinfection procedures and testing. On July 27, the test results verified that the system was ready to treat water and deliver it to the distribution system. Well 10 was brought online on July 28. We completed our mission, and the City’s watering ban was lifted on August 1.
The enclosures at Well 3 and Well 10 were constructed using insulated steel panels that retain the temperature of the groundwater around 55 degrees.
Our team’s deep knowledge of the water system infrastructure and our ability to quickly coordinate and organize with City staff were critical to the success of the project. The initial project is complete, with full temporary buildings around each water treatment plant. Now there is time to prepare for a permanent solution.
Because of our hard work and dedication, we were able to stick to an extremely shortened timeline, meet the updated MDH standards, and were recently awarded the APWA-MN Project of the Year. Helping a community in need resolve a critical issue helps me appreciate our promise to “design with community in mind.”
About the Author
Mark Rolfs is a principal and engineer, leading our team in St. Paul, Minnesota. With more than 37 years of experience, he works primarily on water and wastewater projects.More Content by Mark Rolfs