memorandum

TO: Timothy Navarre, Assembly President

Kenai Peninsula Borough Assembly Members

THRU: Dale Bagley, Borough Mayor

THRU: Robert Bright, Planning Director

FROM: Rachel Clark, Planner

SUBJECT: Nanwalek Elementary/high School Cleanup Action

DATE: May 2, 2001

Diesel-contaminated soil was found at the Nanwalek Elementary/High School during routine maintenance work at the school playground in the summer of 2000. The school has not used diesel for heat since approximately 1981. Records exist verifying at least one, and possibly several significant spills at the school prior to 1981.

In the Fall of 2000, the Planning Department hired a consultant to assess the levels and extent of contamination at the site. Diesel range organics (DRO) in the soil ranged from non-detect to 7410 mg/kg. Groundwater contamination ranged from non-detect to 13.3 mg/L DRO. All other constituents were below the maximum contaminant levels (MCL) allowable by law, shown below for DRO:

All of the soil met the MCL for ingestion and inhalation, so there is no reason to believe a health hazard exists. However, a significant portion of the test holes had levels above the MCL for migration to groundwater, and some of the monitoring wells were above allowable limits. Based on these results, the Borough is required to perform a cleanup action at the site. Should the cleanup action result in groundwater levels below 1.5 mg/L, we will apply for a "ten times rule" where the MCL will be raised to ten times allowable to 2,300 mg/Kg. Based on the target cleanup level of 2,300 mg/Kg in the soil, the Planning Department proposes to remove impacted soils at the west playground:

1. Within 1 foot of the surface if contamination exceeds 230 mg/Kg; and

2. Below 1 foot if contamination exceed 2,300 mg/Kg or where contamination contributes to elevated concentrations in groundwater at the property line.

These soils will be stored on-site in an ADEC approved storage cell. If the project is successful in reducing groundwater levels, the soil will be removed from the site next year and remediated. The site restoration may require replacement of the demolished playground equipment.

In addition to the excavation described above, ADEC has requested additional assessment at three areas on the site. The Village of Nanwalek has also requested one additional test hole on the west side of the school.

Based on the proposed work, the Planning Department respectively requests $132,400 from the Land Trust Fund Balance for this cleanup action. We propose a shortened hearing schedule to ensure the work can be completed this summer, prior to students returning to the school.