- Client US Department of Agriculture, Agricultural Research Service
- Location Ames, Iowa
The USDA operates the National Centers for Animal Health (NCAH), a secure facility, in Ames, Iowa. It houses diseased animals that generate various forms of waste. Each animal and laboratory has an independent wastewater pumping system to avoid spreading disease to other animals both inside and outside the facility. The waste is thermally processed through a wastewater pretreatment plant (WWPTP) before being cooled and discharged to the municipal sanitary sewer for final treatment through their wastewater treatment plant. While each remote building had its own pumping stations to direct flow to the main Plant, a pipe manifold with isolation valves at the main building was used to collect the feeds. Under this configuration, there was a possibility of one building’s flow to contaminate another building, if it’s pumping system was to be overpowered.
The GES team designed the reconfiguration of the wastewater supply piping system to reduce potential for cross-contamination of wastewater between buildings. We studied the system and designed valves and backflow preventers on each of the incoming waste pipes from each of the buildings into the WWPTP. We also provided pipe feeds/risers to allow each remote building flow to enter its storage tank without the use of a common manifold.
The design underwent extensive reviews by the local personnel and maintenance department, and the final product was determined after multiple site visits and on-site meetings. It was also challenging to schedule the construction work, since special procedures and clearances needed to be established for the working contractor, as well a carefully detailed phasing construction plan to allow uncompromised continuous operation of the plan during the construction.
The pretreated waste includes both Biosafety Level (BSL)-2 and -3 waste, contained at all times in piping, tanks, and heat exchangers so the building did not have to be designed or constructed to a BSL-2 or BSL-3 standard, keeping the construction cost low. The building’s design does include materials and elements to limit exposure in the event of a leak in the process area. The design minimizes air infiltration and waste leakage to outdoors in the event of a leak. The heating, venting, and air conditioning (HVAC) equipment and control methods were designed to have the process area normally operate at a negative pressure so air can be filtered before being discharged outside. Process vents and HVAC also include HEPA filters. Each animal and laboratory has an independent wastewater pumping system to collect wastewater and pump it to the plant.
The WWPTP is designed to treat 100,000 gallons in a 16-hour period to a peak of 275 degrees F for one hour, taking one hour to fill and heat the tank; actual operations expected at start-up are 250 degrees F for 30 minutes with a fill and heating time of 30 minutes. The WWPTP uses steam from the Steam Plant (Building 154) to heat the waste, and heat exchangers to recover the heat as an energy savings measure; it also assists in lowering the temperature of the treated waste to 150 degrees F before it is discharged to the municipal sanitary sewer.
Prior to starting work on the design, the Engineering team conducted a survey of the space, as well as reviewed the existing as-built drawings.
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