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Photo of the Effigy Mounds National Monument Visitor Center and the eastern end of the proposed project area.

Replace Critical Septic System at EFMO Headquarters Area

Effigy Mounds National Monument » Replace Critical Septic System at EFMO Headquarters Area » Document List

Most of the infrastructure you see - or don't see - when you enter the headquarters area at Effigy Mounds National Monument was constructed back in 1959 and 1960. This includes the large septic system that handles wastewater from the Visitor Center. During 2015, this septic system began to exhibit signs of impending failure, leading Effigy Mounds NM staff to begin preliminary discussions with tribal and state historic preservation partners over what a replacement project might look like.

The park's headquarters area is located on a terrace that was once home to dozens of burial mounds. The mounds on this terrace were described by T. H. Lewis of the Northwestern Archaeological Survey in the 1890s, and by that time they were already described as being damaged by agriculture and looters. By the time the terrace was incorporated into Effigy Mounds National Monument in 1949, the above ground portions of most of these mounds had already been obliterated. Later studies revealed that in some cases, remnants of these mounds may still exist in the area, making it critically important to engage thoughtfully and extensively with our tribal partners.

Since the fall of 2017, wastewater has been unable to flow beyond the septic tank. A line of portable toilets was installed between the Visitor Center and parking lot to make it through the busy fall season, and all events were cancelled in the Visitor Center for the winter of 2017-18 in order to keep visitation low enough to allow indoor restrooms during the cold winter months. In the spring, as visitation begins to return, the portable toilets will return to the park until a new system is constructed.

This project proposes a new septic system for the Effigy Mounds National Monument Visitor Center, to be constructed in the grassy areas between the Visitor Center and the south side of the parking lot, extending towards the entrance sign and slightly beyond. Soils in this area performed well in percolation tests, and it is believed the original surface soils were bladed away in this area during the 1959 construction of the parking lot. Every effort will be made to verify this prior to construction.

Many options were explored, but most were eventually deemed undesirable for one reason or another. And that brings us to our proposed system. We hope you will take the time to give it some consideration, and to share your thoughts with us on this critically-important project.

Jim Nepstad

Contact Information
Jim Nepstad
(563) 873-3491, x101