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Consent Decree Exhibit C The potential exposure pathway for sediments in the perimeter ditches is direct contact. The point of compliance for direct contact is the exposed surface of the sediments. 3.4.3 Nature and Extent of Contamination 3.4.3.1 Surface Water Surface water cleanup levels were exceeded in the most recent (November 1999) sampling for copper, nickel and zinc at SW-4 in the West Ditch (see Figure 3-3 for sampling locations). This location receives surface water runoff contribution from the small, western watershed of the landfill. It also receives a small contribution from the BNSF spur (turkey) line. The source of the zinc, copper, and nickel could have originated from either the landfill surface or the spur rail line. Additional investigation will be required to verify the validity of this sample result and determine its likely source. Zinc only slightly exceeded the surface water cleanup levels at SW-2, the discharge into the Snohomish River. Copper and nickel were below cleanup levels at SW-2. The concentrations of zinc, copper and nickel measured at SW-1 (where the northern reach of East Ditch discharges from the Everett Landfill/Tire Fire Site) were less than the cleanup levels. No other surface water samples were collected between SW-4 (West Ditch) and SW-2. Nor were any samples collected at the confluence of the north and south reaches of East Ditch before its discharge to the drainage channel to the Snohomish River. Although it is possible that the zinc result at SW-2 represents a dilution of the higher reading at SW-4, there are insufficient data to reasonably draw that conclusion. Additional monitoring is required to further evaluate the validity, extent and source of the zinc results. Future compliance monitoring is required to include sufficient sampling sites to differentiate between contamination potentially originating from the landfill and contamination originating from off -site sources. 3.4.3.2 Ditch Sediment The cleanup level for total c-PAHs was exceeded at location SED-3 in the most recent (November 1999) sampling. This location is considered background to the East Ditch. Environmental Partners (1999) discovered GPAHs in the Mid -East Ditch, outside any runoff from the landfill. This suggests another source of c-PAH contamination other than the landfill. One such source could be rail ties from adjacent rail lines. The slight arsenic exceedance in the duplicate sample SED-6 is not considered representative given the substantially lower arsenic concentration in the other duplicate sample, SED-5. When averaged, the result is well below the cleanup standard. The cleanup level for TPH, as measured in March 1997, was exceeded at an off -site sampling location where the culvert carrying flow from the East and Mid -East Ditches discharges to the Snohomish River. TPH is likely originating from urban runoff from the upland drainage basin and from runoff from the adjacent railroad tracks. Environmental Partners (1999) also found TPH-D (diesel) at 180 ppm and TPH-O (heavy oil) at 1,500 ppm in Mid -East Ditch sediments where the Mid -East Ditch discharges to the channel flowing to the Snohomish River. Since the sampling location is off -site and the Mid -East Ditch is not subject to landfill runoff, these results support the conclusion that any TPH is originating off -site. FINAL - March 2001 3-7 Everett Landfill Tire Fire Site Cleanup Action Plan 1