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SJC/PHS/EHD COMMENTS DRAFT FIELD INVESTIGATION WORKPLAN FOR OIL/WATER SEPARATOR(OWS) SITES BUILDINGS 12, 410,AND 508 Friday, July 02, 1999 Building 12,410 and 508 OWS proposed borehole positions: 1) PHS/EHD requests 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). 2) All OSW's 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 OWS system was not leaking prior to the time of transfer. 3.) In the event floor drains are connected to the OWS network PHS/EHD recommends subsurface sampling at these locations. No additional comments at this time. Please provide PHS/EHD with a final workplan for review at your earliest convenience.