The National Park Service is proposing to build a new septic system to replace the failing one at Effigy Mounds National Monument in Iowa/NPS

Planning is under way to replace the failing sewer system at Effigy Mounds National Monument in Iowa with a larger system that should serve the park's needs for 30 years.

The park recently completed a draft environmental assessment on the planned system, and is seeking public comment on the proposal.

The current septic system dates to 1959 and can't meet the needs of visitors. The EA assesses the impacts associated with either keeping things as they are, or installing a new system in the area between the main parking lot and Highway 76.

“Ground disturbance in a park like Effigy Mounds National Monument is something that must be done with the utmost care,” said Superintendent Jim Nepstad. “In preparation for an eventual replacement project, we have been consulting with our tribal and state historic preservation partners on this since the current system started having problems a couple of years ago. The current system has failed now, so we need to act.”

The new system will be designed to accommodate the park’s 70,000 - 80,000 annual visitors, and could be expanded if needed. The proposed location for the new system is believed to have been heavily impacted back in 1959, when the majority of the park’s infrastructure was constructed. Most of this area appears to have been scraped below the cultural zone to create fill that was used to level off lows spots in what became the parking lot. A series of soil profiles will be drilled to confirm that this is the case, and the new system will be shifted accordingly if anything is found.

The superintendent said that while funding is on hand for the new system, the exact cost won't be known until after pre-construction archaeological work lets planners determine the precise route of the lines, and possibly even the means of getting those lines in place.

“The heaviest ground disturbance will take place in the location least likely to have any remaining archeological context,” Superintendent Nepstad continued. “Out of an abundance of caution, we will double-check ourselves before construction starts to ensure that assumption is correct. New lines will be installed with directional boring equipment to minimize trenching, but parts of the new system will require traditional excavation. Qualified archeologists will carefully monitor all work, and tribal monitoring of the project is being encouraged.”

Copies of the septic system EA are available at this site, and comments may be electronically submitted there as well. The EA will be available for public comment through March 18. A public open house will be held February 28, from 2 p.m. to 5:30 p.m., at the Effigy Mounds National Monument Visitor Center located three miles north of Marquette, Iowa, on Highway 76. The open house will provide the public with an opportunity to speak with NPS subject matter experts about the project and the precautions being taken.