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ENVIRONMENTAL. RISK SERVICES r' <br /> i <br /> CORPORATION <br /> January 15,2014 <br /> Ms.Kathleen Amaru <br /> Associate Engineering Geologist <br /> Region 5-California Regional'"rater Quality Control Board <br /> 11020 Sun Center Drive#200 <br /> Rancho Cordova, CA 95670-6114 <br /> Re:Workplan for Destruction of"Tells at Union Pacific Rail Site—Rough and Ready Island, Port of <br /> Stockton <br /> Dear Ms. Amaru, <br /> This workplan formally requests Regional Board concurrence to properly abandon wells and piezometers <br /> at the Union Pacific Rail Site—Rough and Ready Island,Port of Stockton(UP Rail Site)to accommodate a <br /> planned rail fabrication facility at the Port of Stockton (Port). Union Pacific intends to begin construction <br /> in portions of this facility at the beginning of February 2014. <br /> Local Geology and Hydrogeologic Structure <br /> Like much of Rough and Read),Island, the UP Rail Site is underlain by mixed fluvial and deltaic <br /> sediments,as seen in the attached well logs(Appendix B). The uppermost 10 feet consist mainly of <br /> interbedded organic-rich brown silt and sand with some peat. Underlying these is dark gray,soft, moist, <br /> medium- to high-plasticity clay. The clay layer grades into silty clay to clayey silt with lenses of silt and <br /> sand, and a deeper saturated silty- to clean sand approximately 3 to 8 feet thick. Beneath this layer of <br /> organic matter are clays and/or silts with little or no sand content that constitute an Island-wide layer of <br /> low hydraulic conductivity. <br /> Similar to other islands in the Delta, the surface of RRI is several feet below mean sea level (msl). A levee <br /> protects the Island from the adjacent San Joaquin River, which is several feet above mean sea level. The <br /> Island ground surface is kept dry by a complex system of interior ground water drainage channels. <br /> These Island drainage channels direct water to the southwest where the water is then returned to the <br /> River. <br /> Identification of Wells and Piezometers to be Abandoned <br /> The table below shows construction details for wells and piezometers that lie within the area of <br /> construction for the UP rail facility(Figure 1): <br /> 1600 Riviera Avenue,Suite 310,Walnut Creek,California 94596 <br /> 925 938 1600-erscorp us <br />