Pierre Sanitary Landfill

Interstate Engineering was selected by the City of Pierre to complete construction and final closure documentation of the Pierre Sanitary Landfill.  Several unique and innovative design features were incorporated into the landfill construction due to the climate and landfill topography.  The cover design itself is very different than the traditional compacted clay cover.  The alternate final cover incorporated four layers: a grading layer, an eight inch storage layer, a 12 inch clay barrier layer, and a six inch topsoil layer with vegetation.  The   design utilizes the soil properties of each loosely compacted layer and the vegetation to regulate the moisture in the cover.

The terrain across the landfill posed several challenges to the project.  The landfill is within a gulley that has steep slopes.  With over 200 feet of fall across the project, management of storm water and prevention of erosion was essential.  As part of the landfill closure, the existing leachate pipe under the landfill was connected to the City’s sanitary sewer by installing 700 LF of eight inch PVC.  This allowed for the existing leachate pond to be excavated to remove any sediment, and then to convert the existing pond to a storm water detention pond for storm water management.

The Pierre Sanitary Landfill is the first landfill in South Dakota to use an alternate final cover design for an entire landfill closure.

Interstate Engineering and the City of Pierre were awarded the South Dakota Engineering Society’s “2006 Outstanding Engineering Achievement Award” for the State of South Dakota for the design of the Pierre Sanitary Landfill.  The project was nominated for this award by the Central Chapter of the South Dakota Engineering Society following its completion.  

Interstate Engineering was responsible for the design and construction engineering of the final cover, which utilized the first alternate cover design in the State of South Dakota.