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AGS ATTACHMENT 2 RESPONSE TO SAN JOAQUIN COUNTY,PHS/EHD COMMENTS Comment 1: PHS/EHD requests that at least one soil sample be collected at a depth not greater than 2 feet below the bottom of any device in the OWS network (devices include tanks, piping/fittings, catch basins, OWS to Sanitary Sewer junctions, and the like). Response: With the exception of OWS components identified in Comments 2 and 3 below, all devices in the OWS system are adequately covered by the currently proposed borehole locations. The proposed depth of soil samples are in accordance with the above stated requirement, with the exception of the waste oil tank borings, where soil samples are proposed to be collected at the water table interface if the bottom of the tank vault occurs beneath the water table. Borehole coverage of system components identified in Comments 2 and 3 are addressed below in the responses to those comments. Comment 2: All OWSs have an axial and distal component. In order to assess the "system" samples should be collected at each end to assess "system integrity/continuity." The Oil/Water Separators in all cases are connected by discharge piping to the sanitary sewer as shown on Figures 3, 4, and 5 (presumably to a larger downstream collector pipe). Soluble and insoluble fractions are likely to be transported downstream to the sanitary sewer connection/collector. Any leaks in piping releasing soluble and insoluble fractions of wastewater to the subsurface pose a potential risk as thin alluvial deposits are less likely to be protective of the shallow (vulnerable) groundwater below. PHS/EHD recommends that the piping to the downstream sanitary sewer connection be assessed at a maximum rate of once per 20 lineal feet in soil only at this time (not deeper than 2 feet below the bottom of the piping run). One borehole with a soil and groundwater grab at the junction of the OWS discharge to sanitary sewer collector is recommended for each site. This recommendation is provided considering the proposed transfer of these devices to a future user. The current owner/operator may wish to document that the entire system was not leaking prior to the time of transfer. Response: The Navy desires that the integrity of the entire OWS system be addressed in the current investigation. Accordingly, the Work Plan will be revised to incorporate the above recommendations by adding borehole locations at the distal end of the OWS C.\W pavi n60\W PDOCS\95-CLTS\1995\950304p\sjcehd resp.doc 1