Collier Tunnel SRRA Wastewater Upgrade Project
Collier Tunnel SRRA Wastewater Upgrade Project
Client: Caltrans vis NorthStar Engineering
Location: Northern CA on SR199 4 miles south of the CA-OR border
Lopez Engineering, Inc. (LEI) served as a sub-contractor to NorthStar Engineering, which had the prime contract with Caltrans. This task order is part of the IDIQ that NorthStar with LEI as a sub-consultant has with Caltrans. Key LEI personnel included John Lopez, PE, Neil Sherer, Bela Wouters, Donald Crawford and Wesley Breckenridge. The LEI team designed the electrical and SCADA systems for the Collier Tunnel SRRA on SR199 just south of Collier Tunnel, approximately four miles south of the CA-OR border.
The wastewater system consists of a lift station receiving liquid from the toilets and sinks; a urine tank receiving liquid from the urinals, a septic tank, two up flow solids tanks, two anaerobic filter tanks; an equalization tank, a secondary treatment tank, headworks with filter flush feature, and three dispersal field zones. System Control and Data Acquisition (SCADA) acquires data from and/or controls level sensors, float switches, scum/sludge sensor study, liquid meters, valves with valve actuators, pump electrical current sensors, calendar, run time meters, and starters. The XiO SCADA system is used for data acquisition and control. Typically, this system is installed by an electrician in one day, the system testing is performed using the cloud, and the installation price is approximately 90% less than the SCADA normally used for this application.
LEI developed the Sequence of Operation (SOO), ladder diagrams, control panel layouts, site plans, conduit schedules, and equipment schedules. Level sensors with adjustable settings start and stop some pumps while time measurements (time duration) start and stop other pumps and control the valve actuators. Float switches provide a failsafe backup pump control system. The engine generator is monitored by the XiO, which documents starts, stops, load, and runtime.
LEI design increased the electrical capacity at the Collier Tunnel SRRA site by a factor of three (from 37.5 kVA to 112.5 kVA) and brings 3 phase 480-volt service to the site to serve pump motors 1/2 HP and larger with 3 phase 480-volt power compared to the existing 240-volt singe phase service, which currently serves the Collier Tunnel SRRA. This 3 phase 480-volt power is brought to the site by removing two 2/0 electrical conductors from a 1 1/2" conduit and installing three #1 electrical conductors and a #6 ground conductor in that same 1 1/2" conduit. The distance from the electrical room at the North end of Collier Tunnel to the Collier Tunnel SRRA at the Collier Tunnel south end is approximately 2,300 feet.
LEI designed a step-up transformer, 480V, 3 Ø, 3 W to 600V, 3 Ø, 3 W, at the north end’s electrical room and a step-down transformer, 600 V, 3 Ø, 3 W to 480Y/277V, 3 Ø, 4 W, at the south end. The transformers with their load taps can eliminate the voltage drop for that distance and increase the available power three-fold.