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Remediation at this location will involve use of the excavator or backhoe, which will trench down to native soil beneath any waste discovered (the current soil cap will be removed). Comments: During waste excavation remedial action, will the existing soil cap be separately stockpiled, tested and reused on site? Will samples be collected to confirm the underlying native soil samples are not adversely impacted and that wastes were adequately removed? There is no mention of collecting and analyzing soil confirmation samples which is typically conducted (standard of care) for waste excavation remedial action. AGE anticipates that approximately 2,000 square feet of area (30 to 35 feet north to soil[south] and 65-70 feet east to west) [has] demonstrates some waste glass and debris, with a variable thickness. Removal of the waste to a Class 11 landfill is proposed. Trenching or excavations will remove the waste and be required to adequately define the horizontal and vertical extent of the potentially buried waste. Excavation [to] will be required to depths of 10 feet at some locations, with the use of an excavator through the encountered waste glass and near native soil. Comments: what is meant by excavation will be required through waste glass and "near native soil?" This statement suggests waste excavation will proceed only to "near" native soil and not extend one to two feet into the native soil and be accompanied by confirmation sampling and analytical testing as is typically done. What is meant by "has demonstrates?" This terminology is confusing. "Variable thickness" is not adequate, the range of thickness of wastes based on exploratory trenching needs to be provided. Figure 2 should indicate whether wastes were encountered and waste thicknesses when encountered at each individual trench location and use this information as well as historical aerial photographs, background information and geophysical survey data to delineate the estimated area of planned waste excavation. The wording of this paragraph is difficult to understand. Waste disposal to a Class II landfill suggests wastes were not accepted at a Class III site. The excavation producing a volume of 650 cubic yards of exposed and potential waste, will remove the waste and reduce future need to mitigate waste. Waste glass is proposed to be loaded into end dump trucks for transport to Forward Landfill under special waste manifest. Waste which has been stockpiled will be loaded for trucking and disposal at an appropriate landfill. A plastic sheet barrier will be installed at the western edge of the property boundary, prior to backfilling native clean soil from the property area undisturbed by waste handling. Comments: How can the volume of waste to be excavated be stated before waste excavation has been conducted and what is this volume based on since it appears that waste delineation in this area was not complete based on available documents for review. At best, this is an estimated volume. What is meant by the term "special waste manifest?" The paragraph states that "waste glass" is proposed to be loaded into end dump trucks, so is the waste in this area of planned excavation the same as the wastes to the north?Why is this area being excavated if it contains glass wastes and the area to the north which reportedly also contains glass wastes not being excavated? Based on subsequent information regarding the planned future land use of the property, more specifically the location of the proposed warehouse building, it is not clear why wastes were planned to be excavated at a location south of the planned structure. If wastes were planned to be excavated, then the preferred location would appear to be beneath the proposed building footprint rather than the area of planned and subsequently conducted waste excavation to the south, a location outlying the planned warehouse building. It is not clear why wastes were excavated only in this area unless it was thought this would result in a clean closure of the WDS, which would not be the case, since wastes remain at the site after the planned limited excavation is completed. Maybe the waste area to the north was not planned to be excavated since it had been covered. Because of how the Project documents were written, rationale for why waste was removed to the south and not to the north was not provided. It is not clear why wastes were removed in the area to the south and why other alternatives such as covering the wastes, a much cheaper remedial action were not considered. Ninyo&Moore 1 500 E.Louise Avenue,Lathrop,San Joaquin County,California 1 104690095 1 August 11,2017 41