The City of Simi Valley (City), Public Works Department (Department), Sanitation Services, is requesting proposals (Proposals) from Consultants to prepare a Retrofit Design (Design) for the Water Quality Control Plant’s (WQCP) Digesters 3 and 4 Mixer, located at 600 West Los Angeles Avenue, Simi Valley, CA 93065. The City owns and operates the WQCP that has a design capacity of 12.5 million gallons per day (MGD). Current average annual flow is approximately 8 MGD. Solids treatment at the WQCP consists of primary sludge removal, gravity thickening of waste activated sludge, anaerobic digestion using two (2) primary digesters (Digesters 3 and 4). Both digesters are 65 feet in diameter and 51 feet deep, and are powered from a Motor Control Center (MCC) M that is 100 feet from the digesters. Currently, Digester 3 has installed a gas lance, and Digester 4 has an internal motor and propeller mixing system. Digester 4 was recently rehabilitated by installing a new heat exchanger, gas piping, coatings of the supernatant box and tank interiors, and new supernatant box piping, whereas Digester 3 will require heat exchanger installation and rehabilitation. The City intends to replace both mixing systems in Digesters 3 and 4, rehabilitate Digester 3, and perform touch-up coating work and add two (2) steel cover plates to Digester 4.
