Description: As part of a CMAR delivery team with HDR and Clark Construction, Dutchland built three anaerobic digestion tanks for the Little Patuxent WRP in Howard County, MD. Dutchland served as the Structural Engineer of Record for the project. The tanks were needed to replace two Dutchland tanks that were never put in service due to wastewater conveyance issues from a local dairy.

Each precast digester has an 80-ft diameter and 45-ft tall insulated wall panels. The interior of one of the digesters is lined with Ameron T-Lock to protect the concrete from the corrosive contents. The T-lock was cast in during fabrication and the joints were welded in the field. All three digesters have cast-in reveals for aesthetic purposes. Two digesters have steel roofs that were welded on-site while the third digester is topped with a membrane roof.

Due to site constraints, a control building is common-walled between the three digesters. The control building measures 109’-1” long by 50’-3” wide by 38’ tall and contains blowers, pipes, and pumps for the digesters. One of building walls is designed with a three hour fire rating.

The geometry of the project, in addition to a very tight site, presented challenges for construction. Two digesters and the control building were constructed before the base slab of third digester could be poured. However, Dutchland was able to construct the digesters and building in less than 26 weeks on-site.