State of Oregon

Department of Environmental Quality       Memorandum

_____________________________________________________________________________________

Date:    October 12, 2004

To:    Matt Tracy

   Columbia County Solid Waste Administrator

From:    Bob Schwarz

   Eastern Region Cleanup Program

Subject:   Santosh Landfill investigation – project status

This memo summarizes the status of DEQ’s environmental investigation concerning the Santosh Landfill. The items included in this memo will be discussed in more detail at a public meeting scheduled for October 28, 2004, 5:30 pm at Scappoose High School.

Sampling of domestic wells. DEQ collected water samples from 25 domestic wells. Each well was sampled for volatile organic compounds, certain semivolatile organic compounds (PAHs), PCBs, pesticides, and metals. One organic compound, benzo(b)fluoranthene, was found in one well at a low concentration. Most of the metals were detected in at least one well. This is not unusual because metals occur naturally in most places. Some metals (e.g., iron, lead, copper) can leach into water from a building’s plumbing. The attached table shows concentrations of metals (and benzo(b)fluoranthene) in each well. None of the other contaminants was found in any well.

For comparison, the table also shows MCLs and PRGs published by the US Environmental Protection Agency. MCLs, or maximum contaminant levels, are legally enforceable standards that apply to public water systems. PRGs, or preliminary remediation goals, are guidelines used for evaluating human health risk posed by contaminated sites.

Key points regarding these results:

•  Two wells have concentrations of lead that exceed MCLs. In response to these results, DEQ sampled water from taps at the Frank Knusel and Ryan Irving residences. Lead was not detected in the tap water at either residence.

•  PRGs are exceeded for arsenic in 9 wells, for iron in one well, and manganese in seven wells.

•  These results do not indicate that domestic wells are affected by contamination from the landfill. The ongoing investigation at the landfill will provide more conclusive information regarding how far contamination from the landfill extends.

Initial sampling at the landfill. On September 21, 2004, DEQ collected groundwater samples from three monitoring wells at the Santosh Landfill, and seven soil samples immediately adjacent to the landfill. Samples were analyzed for volatile and semivolatile organic compounds, metals, pesticides, PCBs, dioxins, gamma radiation and other parameters.

The monitoring wells that we sampled are different from the ones that were used when the landfill was operating. Those wells, which were along the landfill’s perimeter dike, have either been removed or are hidden by dense vegetation. The wells sampled last month are in the middle of the landfill. It is not clear who installed them or when they were installed. Placing wells within a landfill is generally not advised because of the risk that they could provide a pathway for migration of contaminants down into the aquifer. We therefore intend to remove these wells, clear vegetation in an attempt to locate the perimeter wells, and install new wells as needed.

More comprehensive sampling at the landfill. DEQ and its Contractor are developing a scope of work for a more thorough site investigation. Activities will include the following:

•  Clear vegetation from the landfill perimeter for the purpose of locating existing groundwater monitoring wells and to install new wells.

•  Install new groundwater monitoring wells. (The number and locations of these wells will be determined after we see how many of the original wells are usable.)

•  Decommission the three wells in the interior of the landfill.

•  Collect and analyze samples of groundwater, soil, surface water, sediment and landfill gas.

•  Based on these sample results, determine whether additional groundwater monitoring wells are needed further from the landfill.

Following is a preliminary schedule for the next phase of work (subject to revision pending negotiations with our Contractor):

It is likely that these sample results will indicate that additional groundwater monitoring wells are needed further from the landfill. A schedule for this and other site work will be developed at that time.

Following completion of site sampling, we will conduct a risk assessment to determine whether contamination exceeds safe levels. If so, we will evaluate what remedial measures are needed.