Retrofit Design of Existing WWTF for Nutrient Removal – A Case Study

Woodland Park, Colorado
City of Woodland Park

The City of Woodland Park is a dedicated environmental steward. The City’s existing activated sludge WWTF was designed for BOD reduction and nitrification.

Retrofit design included expansion of organic and hydraulic treatment capacities together with employing biological nutrient removal process technology. Other project elements include construction of an additional clarifier, replacement of the existing chlorine contact basin with UV disinfection, integration of tertiary filtration, replacement of an aging belt filter press with a new, low horsepower screw press as well as relocation and expansion of sludge holding capacity. New process elements will reduce nutrient loading into Trout Creek while also allowing for reuse of plant effluent.

After performing a Plant Performance Evaluation, Site Amendment Approval was obtained by CDPHE. Primary design challenges included working within a limited footprint and manipulating basin configuration to accommodate biological nutrient removal.

While PELs were obtained prior to design, significant uncertainty about future discharge permit limits also had to be considered. Built-in operational flexibility accommodates routine plant maintenance as well as targets potential future discharge permit limits. Finally, and critically, construction sequencing played into both design and value engineering. Construction was completed in Spring 2018.

Budget: $8.1 million