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"glass management area" even though there is nothing to suggest glass was "managed' in this
<br /> area.These are waste disposal areas.
<br /> Northern Covered Waste Disposal Area
<br /> Twenty-three trenches T1 to T23, evaluated the "northern" waste disposal area. All were
<br /> oriented north-south except trench T13 which was oriented east-west and parallel (as opposed
<br /> to perpendicular) to the assumed southern waste disposal boundary. To delineate the lateral
<br /> extent of wastes, trenches should be located at (not within) and perpendicular to the assumed
<br /> waste disposal area boundary/perimeter. More specifically, trenches T1 to T4 should be located
<br /> at the assumed eastern waste extent and oriented east-west and not north-south. Similarly,
<br /> trenches T21 to T23 are located east of the assumed western lateral extent of waste rather than
<br /> at the assumed western boundary and should be perpendicular and not parallel to the assumed
<br /> waste boundary. Only one trench T-13 is located at the assumed southern waste boundary and
<br /> it is oriented in the wrong direction (it should be oriented north-south (perpendicular), not
<br /> parallel to the assumed waste boundary). Trenches T1, T8, T17, T18 and T23 should be located
<br /> at the assumed northern waste boundary. The trench locations appear to have just been placed
<br /> on the figure, with the same generally north-south orientation without regard to delineating the
<br /> suspected lateral extent of waste.
<br /> • Information from historical aerial photographs (Appendix A) and a geophysical survey should also
<br /> have been used to select proposed exploratory trench locations and orientations.
<br /> • Based on available background data reviewed, for exploratory trenches T1 to T23 excavated at
<br /> the northern waste disposal area, samples analyzed appear to only be from a depth of
<br /> approximately 5 feet bgs, corresponding to the total depth typically excavated. Based on analytical
<br /> tables, samples analyzed were only collected from 5 feet bgs from the 23 trenches. It is a not clear
<br /> why all trenches were excavated to 5 feet bgs and all samples were collected from this same
<br /> depth. Based on the trench logs,which appear to have been provided at a later time, trenches T1,
<br /> T2,T3,T4,T7,T8, T9,T10,T11,T12 T15, T16, T17, T18,T19,T21,T22 and T23 contained glass,
<br /> some only trace amounts at depths shallower than 5 feet bgs, the depth sampled. The logs
<br /> also indicated other waste/contamination such as brick/steel frame, plastic, discolored soils, iron
<br /> metal and sheet metal, some of which also should have been sampled and analyzed to
<br /> characterize the wastes. Based on the trench logs, if interpreted correctly, it appears that the
<br /> wastes are shallower than the depth sampled, with wastes occurring at approximately 2 to 4 feet
<br /> bgs and not in the 5 foot samples, the only collected and analyzed sample depth. This appears to
<br /> indicate soil as opposed to waste samples were collected and analyzed and therefore, it appears
<br /> that the wastes were not characterized. Reports and other documents refer to the samples as
<br /> "soil"samples only (there is no mention of waste samples and testing); however, this may only be
<br /> a case of terminology.
<br /> • Typically when conducting a WDS investigation project (e.g., characterizing/delineating wastes),
<br /> samples are collected from the surface/near surface to evaluate the potential presence and
<br /> adequacy of the cover soils, within the wastes (one to several samples depending on field
<br /> observations) to characterize the wastes, and underlying/adjacent to the wastes in native soils to
<br /> confirm they are not impacted. Collecting and analyzing what appear to be only soil samples at the
<br /> same depths, regardless of subsurface conditions encountered, does not adequately characterize
<br /> the wastes.
<br /> Ninyo&Moore 1 500 E.Louise Avenue,Lathrop,San Joaquin County,California 1 104690095 1 August 11,2017
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