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• Project Tasks (aka Proposed Scope of Work) Comments: in general this section describes the <br /> proposed trenching; however rationale is not provided for the proposed locations of the <br /> exploratory trenches which based on other documents, appear to have not taken into account <br /> the possible waste extent based on historical aerial photographs and information obtained <br /> from the earlier borings, and information that would have been provided about waste extent <br /> from a geophysical survey. <br /> • The trenches are proposed to be 18 inches wide, ten feet in depth bsg and approximately 25 <br /> feet in length north to south; producing a volume of 375 cubic feet or approximately 13.9 <br /> cubic yards of exposed soil and potential waste. If no more than 1 cubic yard of waste is <br /> encountered, then the excavation spoil waste (impacted media removed below the stabilized <br /> soil cover) will be considered de minimus. Waste will stockpiled on plastic (10 mil) sheeting <br /> for evaluation and disposal at an appropriate landfill. Comments: As is typical of site <br /> investigations at WDS throughout the state, during the site investigation phase, excavated <br /> wastes are placed back into the excavation from which they were removed in the <br /> approximate reverse order excavated. This alleviates the requirement to manage temporary <br /> stockpiles, eliminates physical hazards of open trenches and there are no costs associated <br /> with the transportation and offsite disposal of excavated materials. <br /> OEach soil sample will be collected with a metric soil sampling slide-hammer, loaded with a <br /> pre-cleaned steel sleeve. The ends of the sleeve will be sealed with a Teflon plastic and end <br /> caps taped over the ends of each sample sleeve. Samples are to be collected by an AGE <br /> representative. Comments: While this sampling method is probably fine, typically soil and <br /> waste samples related to exploratory trenching at WDS are collected by coring the sample <br /> directly into the laboratory supplied glass jar when sampling is at shallow depths or coring or <br /> obtaining the sample from intact masses brought up in the bucket of the excavating <br /> equipment. Cross contamination does not occur using this sampling method and <br /> decontamination of sampling equipment is not required and investigative wastes are not <br /> generated, requiring costly offsite disposal. Information about what types of subsurface <br /> materials are planned to be sampled is missing. Typically samples are collected at or near <br /> the surface to evaluate cover soil, in wastes (the number to be determined based on field <br /> observations) and in the underlying native soils. <br /> *OW <br /> a 'N KN <br /> A 14 Jy'"`� i�� <br /> This email correspondence stated that the LEA has reviewed the report and that they think it <br /> contains some useful information and that there will be additional site work required prior to <br /> signing off on future development. <br /> 10,.,� .. � 1 ma. 10.6 � I I M <br /> This email correspondence from AGE stated that they provided a work plan to investigate the <br /> former waste management area south of 500 East Louise Ave. in Lathrop. "Attached is MFR." <br /> AGE asked what is the status of the workplan approval. <br /> This email correspondence from the LEA to AGE stated that the LEA needs an SR form and <br /> funds for five hours of work on the Project. The LEA stated that they have looked at the plan but <br /> have not"made" comment and "did not see anything that stands out." <br /> Ninyo&Moore 1 500 E.Louise Avenue,Lathrop,San Joaquin County,California 1 104690095 1 August 11,2017 2 <br />