ARCHIVED REPORTS_XR0009071 - Laserfiche WebLink

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' facility located on Rough & Ready Island, a short distance to the west of the Port Administration Buildings. It is accessed from W. Washington Blvd. , which can be reached from Interstate 5 via the Fresno Ave. exit. The surrounding area is zoned for industrial & manufacturing; Tri-Delta Fertilizer company is to the north, a railroad spur on ' the east, and undeveloped vacant land on the west. There are no residences within 1/2 mile of the site. SAT -1 shows the location of the property in relation to nearby features. ' GEOLOGIC & GEOMORPHIC SETTING: The property is located in the southern portion of the Sacramento Valley, at the eastern end of what is referred to as the San Joaquin Delta. This is a large area of sloughs, islands, and channels that were formed by the meanderings of the Mokelumne, ' San Joaquin & Calaveras rivers. The Burns Cutoff is a short distance to the west; it empties into the Stockton Deepwater Channel just to the north. The topography is essentially flat, with drainage towards the west at less than 5' per mile. Sediments consist primarily of unconsolidated clays, silts, sands, and some gravels, typical of ' recent floodplain deposits. Refer to PLATE 11 for details. SOIL TYPES: ' According to a 1952 University of California publication, soils in the area consist of Columbia silty clay loam, dredger fill, and "madeland. " The soil profile revealed by the removal of the ' UST indicated that the top 3-4' consists of fill, underlain by undifferentiated flood plain deposits. PLA .SII shows the general soil profile in the area. ' DEPTH TO GROUNDWATER & LOCATION OF WELLS: According to maps published by the County Flood Control District, groundwater is influenced by tidal action, and ranges from 5 to 10 feet below ground level. Water did not enter the excavation which was about 10' deep after removal of the UST. However, during work covered in this report, the water table was found at a depth of 7 feet, and remained fairly constant during the work. PLATE ly shows depth to groundwater, sea level datum, in the Spring of 1986, the highest recorded levels during the past 10 years. However, it is most likely that the water table in the Port area fluctuates with tidal forces, which may vary by 5 or 6 feet. PLATE indicates the locations of the wells used by the 2