City of Morgan Hill Sewer System Master Plan 2017

2017 City of Morgan Hill 4.0 CHAPTER 4 - EXISTING SEWER COLLECTION FACILITIES This chapter provides a description of the City’s existing sewer system facilities including gravity trunks, force mains, lift stations, and sewer collection basins. The chapter also includes a brief description of the SCRWA Wastewater Treatment Plant. 4.1 SEWER COLLECTION SYSTEM OVERVIEW The City provides sewer collection services to approximately 10,000 residential, commercial, industrial, and institutional accounts. The City’s modeled collection system consists of approximately 160 miles of up to 30-inch gravity sewer pipes that convey flows, via the Morgan Hill-Gilroy Joint Trunk, towards the South County Regional Water Authority WWTP, on Southside Drive in the City of Gilroy, as shown on Figure 4.1 . A system-wide pipe inventory, listing the total length by pipe diameter, is shown on Table 4.1 . This table is based on information extracted from the City’s GIS. The 8 -inch to 15-inch diameter pipes account for 55 percent of the total sewer pipe lengths. 4.2 SEWER COLLECTION BASINS AND TRUNKS Due to topography, the sanitary sewer system is divided into five separate dendritic sewer collection basins, each defining the boundaries of a sewer collection trunk system. The following 6 major sewer collection basins were created and shown on Figure 4.2 : the Butterfield Trunk, the East Dunne Trunk, the Hale-Llagas Trunk, the Hale-Monterey Trunk, the Hill — Barrett Trunk, the Llagas Trunk and the Railroad-Monterey Trunk. The sewer trunk system for each collection basin is shown on Figure 4.3 , and a schematic diagram intended to simplify the connectivity between the basins and trunks is shown on Figure 4.4 . 4.2.1 Butterfield Trunk This trunk starts at the intersection of Cochrane Road and Butterfield Boulevard as a 20-inch gravity main in a southbound direction. The main then follows Butterfield Boulevard before increasing to a 24-inch diameter main just south of the intersection of Jarvis Drive and Butterfield Boulevard, and continues south along Butterfield Boulevard. The Butterfield Trunk ends at the intersection of San Pedro Avenue where it turns west and discharges into the Railroad-Monterey Trunk. 4.2.2 Llagas Trunk This trunk starts west of the intersection of Sanchez Drive and Monterey Road as 15-inch gravity main. The main continues westerly before reaching Del Monte Avenue where it turns south

August 2017

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City of Morgan Hill Sewer System Master Plan