SU-2500946_SSNL - Laserfiche WebLink

Home Browse Search

27 August 2025 AdvancedGeo Project No. 25-8011 An Employee-owned CompaV Page 4 of 14 The current residence on the property has three (3) bedrooms and utilizes the existing septic system 365 days per year. The existing septic system will not be altered from the current configuration. The reasonable or maximum usage of wastewater for a five- bedroom home by residents is 100 gallons per day (gpd)for the first bedroom and 50 gpd for each additional bedroom for a total of 200 gpd. The new proposed septic system is planned to be located in the western portion of the property, over 100 feet away from the existing onsite domestic water well and the surrounding water wells (Figure 2). The proposed septic system will consist of a single 1,200-gallon septic tank and two 80-foot-long leach lines. The septic system will service the proposed ADU to be developed on the property and will be used by the ADU 365 days per year. The average and reasonable maximum usage of wastewater for a two-bedroom ADU by residents is 100 gpd for the first bedroom and 50 gpd for each additional bedroom for a total of 150 gpd for the ADU. 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 is located 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. The GVS extends 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 is 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. Most of the fresh groundwater in the Central Valley is contained in the post-Eocene-aged continental rocks 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 containing individual confining layers. The Modesto, Riverbank, Turlock Lake Formations and overlying recent alluvium are the principal source of domestic groundwater in the 13,500-square mile San Joaquin Valley Groundwater Basin (Basin 5-22). This basin is drained primarily by the San Joaquin River, which is approximately 2.8 miles west of the subject property. The nearest surface water feature to the site is the Duck Creek, which is approximately 1 mile east of the subject property. 4.1. GROUNDWATER DESCRIPTION FOR THE GENERAL AREA