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Administrative Draft Environmental Impact Report Gill Medical Center Project ground cover of weedy plants such as turkey mullein (Croton setigerus), prickly lettuce (Loctuca serriola), English plantain (Plantago lanceolate), and Italian thistle (Carduus pycnocephalus). Fallow Agricultural Field A small area of fallow agricultural field is located in the southeastern corner of the Study Area. At the time of the site visit conducted in May 2020, the field was plowed and did not appear to have been planted with a crop the prior growing season. Plants identified in the fallow agricultural field included a variety of non-native weedy species such as wild oats (Avena fatua), Italian ryegrass (Festuca perennis), broad-leaf pepper grass (Lepidium latifolium), and English plantain. Ruderal/Roadside The ruderal areas found at the property boundaries include weedy annual grassland species with scattered trees.The ruderal areas within the Study Area include dirt access roads and edges of fields that cannot be accessed by farm equipment and dominated by non-native weedy plants. Common herbaceous plants found in the ruderal areas onsite included wild oats, prickly lettuce, English plantain, chicory (Cichorium intybus), and curly dock (Rumex crispus). Scattered trees found adjacent to the irrigation ditch, fence lines, and ruderal areas include valley oak (Quercus lobata), eucalyptus (Eucalyptus species), and walnut (Juglans species). Small patches of Himalayan blackberry (Rubus armeniacus) are found along the southern fence line and the irrigation ditch. 4.6.1.2 Soils According to the Web Soil Survey(NRCS 2O2Oa), there is one soil unit mapped within the Study Area: (180) Jacktone clay, 0 to 2 percent slopes (Figure 4.6-2. Natural Resources Conservation Service Soil Types).This soil unit contains hydric components (NRCS 2O2Ob). If the unit is used for urban development, the main limitations are the high shrink-swell potential, the slow permeability, depth to the hardpan, and low strength. Properly designing foundations and footings and diverting runoff away from buildings help to prevent the structural damage caused by shrinking and swelling. Properly designing buildings can offset the limited ability of the soil to support a load. (Soil Conservation Service 1992). 4.6.1.3 Potential Aquatic Resources A Woodbridge Irrigation District irrigation ditch is located along the northern boundary of the Study Area. The parcel boundary follows the centerline of the ditch. No other potential aquatic resources were identified on the Project Site.There is one California Aquatic Resources Inventory feature mapped, fluvial natural, along the northern boundary (Figure 4.6-3. California Aquatic Resources Inventory).This corresponds to the irrigation ditch. The irrigation ditch supports intermittent flows based on irrigation needs. It is an excavated, unlined, and trapezoidal channel that is approximately 8 to 10 feet wide. Channel vegetation is limited to isolated patches of emergent plants, such as cattail (Typha species), hard-stem bulrush (Schoenoplectus acutus), and soft rush (Juncus effusus). A few scattered valley oak trees are found along the banks of the ditch. Biological Resources 4.6-3 October 2021