A prefabricated wastewater treatment plant is a modular and self-contained system designed for the treatment of wastewater. Unlike traditional wastewater treatment plants, which are typically constructed on-site and involve significant construction, prefabricated treatment plants are built in a factory or an off-site location and then transported to their intended location for installation. These plants are typically compact in design, adaptable to the needs of a specific facility, have a quick installation process, and are cost-effective.
The average life expectancy of a prefabricated plant is 20 to 30 years, while the equipment typically lasts 10 to 15 years.
The existing prefabricated wastewater treatment plant (WWTP) at Boone Grove High School, a public school in Valparaiso, Indiana, was constructed in 1992 and rehabilitated in 2005. The plant is a private system and only serves the needs of the high school. As the WWTP was approaching its 30th year in service and Boone Grove was looking toward future campus expansions, the Porter Township School Corporation engaged JPR to prepare a Preliminary Investigation Report (PIR).
At this time, a new stadium project was anticipated on campus and the existing WWTP was in the footprint of the proposed field. Knowing that the plant would need to be relocated prior to building the stadium, the PIR served as a crucial step in the development process and helped stakeholders and decision-makers make informed choices regarding the feasibility and viability of the project.
Through the PIR, it was determined that the existing WWTP needed to be replaced.
The age of the equipment would pose significant maintenance or replacement requirements in the near future and the majority of the steel that comprised the plant was rusted and in poor condition – especially the steel angles that supported the grating. Additionally, a critical finding was that the existing plant was close to capacity and would not accommodate increased student and staff populations or the additional flow that would come from a new stadium with concessions and restrooms.
Once the decision was made to decommission and remove the existing WWTP, JPR partnered with Tanner Consulting, LLC and Prodecomm Engineering, Inc. to design and permit a new prefabricated wastewater treatment plant –approximately 465 feet from the existing site. This new plant would not only replace the existing one in terms of service, but it would also account for a 42% increase in campus population and accommodate the 1,500-person football stadium.
Once the permits and submittals were in place, on-site construction began in September 2022.
Completion of the WWTP was critical for the construction of the football stadium to begin. However, several delivery chain issues posed challenges to the project timeline. A delay in delivery of an electric transformer that would serve both the WWTP and football stadium would have paused the project for several months. To solve this, a smaller unit was purchased that would serve the needs of the treatment plant only. Additionally, because some equipment delivery lagged behind the delivery of the main plant, several adjustments to equipment and controls were needed to obtain the desirable discharge limits.
Ultimately, equipment delivery was expedited and installed by the manufacturer’s personnel. They worked around the clock during the unit’s start-up to ensure that everything functioned properly.
The liquid material from the existing WWTP, known as mixed liquor, was used to seed the new plant for start-up. Because of the close proximity of the plants and the biological matter being reintroduced to the same waste stream at the new WWTP, utilizing the existing mixed liquor both simplified start-up and established it quickly.
The new plant achieved substantial completion on May 10 and was finalized on October 27, 2023.
Since completion, the new prefabricated WWTP at the Boone Grove High School campus can handle greater loading to serve increased enrollment, staffing, and sporting events. The new system also utilizes current technology and best practices, and the building contains additional storage space for school maintenance and grounds equipment.
Throughout the project, JPR provided project management, topographic and boundary surveys, site design, and permitting, along with bidding, part-time inspection, construction administration, and post-construction services.
The WWTP at Boone Grove is a complete, factory built, prefabricated system manufactured by DPI Water Solutions. The basins are constructed out of painted carbon steel. There are two rectangular units and each unit was transported, mostly assembled, to the site on flatbed trucks. The equalization basin, aeration basin, secondary clarifier, and sludge holding tanks are all contained as one unit, while the tertiary sand filter and ultraviolet disinfection system are both contained in the second. The processes are divided by steel walls. The system contains four blowers and 8 pumps, with stainless steel process piping.
The prefabricated plant is buried in a 6,900 square-foot building, at an approximate depth of 12-feet. One side of the building hosts the WWTP, while the other contains much needed storage space for the school. The plant was buried to keep it insulated from cold winter temperatures; it is also equipped with insulated grating for the same purpose. Having warmer temperatures will assist with ammonia removal during cold weather.