Yelm’s 1.0 mgd water reclamation facility needed upgrades to produce an adequate supply of Class A reclaimed water and to meet expected population growth. Parametrix partnered with the City of Yelm to plan and design the improvements and apply for and receive a State Revolving Fund low interest loan to partially fund the improvements. The project design schedule was compressed from 12 to 8 months to meet key milestones for the loan.

The liquid stream improvements (Schedule A) involve a new 1.39 mgd MBR basin and new headworks with fine screen system and a grit channel. Two existing sequencing batch reactor tanks are being converted to separate anoxic, aerated, and swing zones, each having an individual drop leg and valve for aeration control. Schedule A also provides a new ultraviolet disinfection system, new crane system, and mechanical building with recycle pumps, permeate pumps, and piping for continuous operation. Schedule A also includes a new plant electrical system with new switchgear, new motor controls, emergency generator, and communication system that allows operators to optimize the system, which will result in energy savings.

The solid stream improvements (Schedule B) will be capable of producing high quality Class A biosolid and involve a new centrifuge that will be constructed with polymer feed systems, controls, and conveyors adequate to serve an additional centrifuge when needed. A new bio-dryer will be installed, also planned for future expansion, with up to 3 boilers, odor control, a 2,400-square-foot weather enclosure, and ancillary equipment. A new septage receiving station with screening, valving, and metering will be constructed as well as odor control improvements and a storage tank and pump station. All improvements are being constructed while the plant remains operational throughout.