Sunset Complex Project

The Project, located at the City of Pasadena’s Sunset Reservoir Complex at the northwest corner of the intersection of Sunset Avenue and West Mountain Street (Pasadena, Los Angeles County, CA) consists of replacing two 125-plus-year-old reservoirs (15.5 million gallons) with new prestressed concrete reservoirs (11 million gallons), construction of a new 1,500 gallons per minute (gpm) Ion Exchange and Liquid Granular Activated Carbon groundwater treatment plant (GWTP) with room to expand to 4,500 gpm, and improving existing 1,500 gpm groundwater well. The proposed Project would be composed of multiple structures, including existing, replaced, and newly constructed structures. Additionally, the Project involves the removal and installation of piping, as well as other site improvements related to parking, ingress/egress, etc. The Project would demolish the two existing reservoirs on site, Existing Reservoir 1 and Existing Reservoir 2, including A-Basin. These structures were built in 1888 and 1900, respectively, and provide storage for the City of Pasadena’s water system. These structures would be removed in order to replace them with Proposed Reservoirs 1 and 2. There are several other structures that are being demolished as part of the proposed Project. The Sunset Well Building and Electrical Transformer Area would be removed in its entirety. The Disinfection Facility would be demolished and a new disinfection structure in a different area would be constructed utilizing some of the salvaged equipment, including the existing chemical storage tanks. The Project proposes improvements to several of the existing structures on the site, driveway entrances, fences, and landscaping. The Bangham Well Building will remain, but the well’s existing retention pond, sump pump, valves, elbows, tees, air relief valve, well pump discharge head, column and motor, concrete, fence and assorted piping would be replaced. Architectural modifications to the façade of the Glorieta Booster Station building would occur as part of the Project. Additionally, the Electrical Equipment Enclosure associated with the Glorieta Booster Station would be modified to add an automatic transfer switch for connection to the new standby generator. The Project would construct two new reservoirs at the 7.17-acre site, herein referred to as Proposed Reservoir 1 and Proposed Reservoir 2. Proposed Reservoir 1 would have an inside diameter of approximately 210 feet, a total footprint of 36,530 square feet, and a capacity of 4.9 million gallons (MG). Proposed Reservoir 2 would have an inside diameter of approximately 234 feet, a total footprint of 45,180 square feet, and a capacity of 6.1 MG. Collectively, the two reservoirs would provide a total capacity of 11.0 MG. The proposed reservoirs would be constructed at different sizes due to the geometry of the existing site, which narrows at the south end of the site. By installing the smaller reservoir (Proposed Reservoir 1) in the south end of the site, the Project would be able to preserve more space for the approximately 5,250-square-foot proposed groundwater treatment plant (GWTP) and parking at the north end of the site. Backfill would be placed around both reservoirs, as the reservoirs would be partially buried. The depth of the backfill would be a minimum of 12 feet deep all around the tanks and of sufficient depth to resist the sliding forces of the empty tanks. The finished grade would provide drainage away from the new tanks. The main ingress/egress would be located at the northeast corner of the site. The existing employee entrance to the north along Sunset Avenue would be widened to allow for safety and ease of traffic flow. Additional proposed project components include two backup generators, a groundwater treatment plant consisting of an ion exchange for perchlorate removal and granular activated carbon for volatile organic compound (VOC) removal, an air gap structure, stormwater treatment improvement, solar canopies and rooftop panels, electric vehicle charging stations, a backwash tank, a disinfection facility, and overflow and drains. The current grading plan results in an approximate net export of 3,700 cubic yards (CY).