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19 May 2021 Project No. 21-6435 Page 4 of 14 ADDRESS: 26210 Thornton Road LOCATION: Adjacent property to North SEPTIC SYSTEM: 1) Permit date January 1953; installation of 500-gallon grease pit with one compartment; a filter trap consisting of three 4-foot-deep rock filled holes; and a 12- foot-deep seepage pit lined with brick. 2) Permit date June 1978; installation of 1,200- gallon concrete grease trap with two compartments. 3) Permit date March 1995; repair and addition of existing sewer line to septic tank. 3.6. PROPOSED MAXIMUM SEPTIC TANK USAGE ON SITE The current residences on the property have a total of six (6) bedrooms and utilize the existing septic system 365 days per year. The average and reasonable maximum usage of wastewater for six bedrooms is 100 gpd for the first bedroom and 50 gpd for each additional bedroom for a total of 350 gpd. The existing septic system will also service the proposed research facility. The hours of operations for the research facility will be between 9:00am and 5:00pm, Monday through Friday. The average and reasonable usage of 5 to 10 gpd per person is typical for an individual to the site setting, and a maximum usage of 15 to 20 gpd per person is typical for an individual to the site setting. The septic system will be utilized by the research facility 260 days per year by a maximum of six (6) full-time employees. The reasonable or maximum usage of wastewater for the facility is 20 gpd per person for a total of 120 gpd. 4.0. GROUNDWATER INFORMATION - REGIONAL HYDROGEOLOGY The Geologic Map of California, published in 1966 by the California Department of Conservation Division of Mines and Geology, shows the site area within the Great Valley Syncline (GVS), a large, elongate, northwest trending structural trough. The GVS is subdivided into two major divisions designated the Sacramento and San Joaquin Valleys, which have been filled to the present elevation with thick sequences of sediment ranging in age from Jurassic to present day, creating a nearly flat-lying alluvial plain extending from the Tehachapi Mountains in the south to the Klamath Mountains in the north. The western and eastern boundaries of this province are comprised of the California Coast Range and the Sierra Nevada, respectively. Geologically, the area around the property generally consists of Holocene-aged flood-basin deposits of clay, silt, and sand. Miocene to Holocene age-units are located in the surrounding area. These deposits are heterogeneous mix of generally poorly sorted clay, silt, sand, and gravel with some beds of claystone, siltstone, sandstone, and conglomerate (1986). Most of the fresh groundwater in the Central Valley is contained in the post-Eocene-aged continental rocks and deposits and in the Holocene-aged river deposits consisting of gravel, sand, silt, and minor amounts of clay. In general, these geologic materials comprise a major widespread aquifer extending hundreds of feet deep and occasionally