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Lebanon Hills Iron-Enhanced Sand Filter

Lebanon Hills IESF banner image
Lebanon Hills Iron-Enhanced Sand Filter

Location:  Apple Valley, Minnesota
Client:  Dakota County


In 2019, Dakota County hired Houston Engineering, Inc. (HEI) to provide conceptual alternatives, final design, and construction documents for two iron-enhanced sand filters (IESFs) with automated control in Lebanon Hills Regional Park.

The Project

This project is largely funded by a grant from the Minnesota's Clean Water Fund. Because of this, our team must ensure any deviations from the project’s design still satisfy grant requirements.  

Our team began this project with a site visit with the project partners to evaluate the park’s current conditions to better inform the design. 

Our team worked with the County to discuss potential design alternatives before conceptual plans continued. HEI investigated the feasibility of proprietary treatment solutions and recommended the best treatment design.

HEI’s design team completed the design, cost estimate, and review process for 30%, 60%, and 90% design documents. These two IESF systems feature automated control to ensure the proper filter dosing and rest times required for the phosphorus treatment. One system uses a pump-and-treat method, which was originally developed by HEI. The second is a novel system that is gravity fed, with flow directed by automated valves to three separated IESF beds to provide continuous treatment. 

These final documents also include an engineering cost estimate, water quality benefit of the IESF, and maintenance manual for the IESF system.

Client Benefits

  • Custom design to treat dissolved phosphorus in baseflow conditions. 
  • First-of-its-kind IESF using gravity and automated valves to control flows. 
  • Remote monitoring and system control through cellular service. 
  • Design and construction plans at the 30%, 60%, 90%, and 100% design phases to ensure the County and its partners are given the opportunity to provide input at every step of the design process.
  • Cost-effective practices throughout the project to ensure grant dollars are used wisely.

Learn more about pump-and-treat IESFs in this article.