South Hill Was a Superfund Site

by Carl Vest

At the southern end of South Hill there is a site that over the years has been considered one of the most polluted spots in Pierce County.  It has received attention from three levels of environmental agencies:  Federal, state and local.  Located near the southeast intersection of Meridian Avenue, and 176th Street the spot is identified by a number of different names depending on which data base is consulted:  The Hidden Valley Landfill, the Thun Field site, Pierce County Landfill, the closed county dump, as well as other labels.  The location is important because it overlies the Central Pierce County Aquifer System, a sole source water pool for a large number of citizens on South Hill.

The Federal Environmental Protection Agency (EPA) has designated this place a Superfund Site.  Superfund is the shorthand name for the Federal Comprehensive Environmental Response, Compensation and Liability Act of 1980.  It gives Federal authorities the right to identify and to clean up hazardous substances that may endanger human health or the environment. 

The problem was created some five decades ago.  In 1967, for example, the 92 acre setting was operating both as a gravel pit and a landfill.  According to EPA, until 1985 the landfill accepted liquids, solids, industrial wastes, and heavy metal sludges.  Most importantly, it was determined that fifty-six acres under the landfill had no ground protection.  During its investigation EPA declared that the “Groundwater beneath the site and leachate in the landfill are contaminated with metals, volatile organic compounds (VOCs), and nitrates.”  And, since there was no liner it was anticipated that rain water would filter through the collection and eventually all the contaminants could be deposited into South Hill’s only  water source.

EPA proposed placing the site on its National Priorities List (NPL) in 1986.  The listing was accomplished in 1989.  It was also in 1989 that the unprotected landfill stopped accepting waste and clean-up got started.  One early action was the installation of a gas control system.  This effort has been modified several times during the past two decades, most recently to convert waste into energy and supply electricity to a compost facility adjacent to the landfill. 

In 1992 a Remedial Investigation and Feasibility Study of the location was completed.  In the year 2000 a final Cleanup Action Plan (CAP) was finished.  The required remedial action was aimed at minimizing production and movement of water through the fill.   According to EPA records the required corrective actions included, covering the waste with an impermeable barrier to control water leaking into the ground, the collecting of landfill gases, the controlling of surface water and soil erosion, the limiting of human and animal contact with the waste, and minimizing the lateral and vertical movement of contaminated groundwater.   CAP required that ultimately the landfill be closed.  Closure  has now been accomplished and it has been capped.

An additional requirement was that the site be monitored for compliance, and approved institutional controls be implemented.  As of 2010 the site is still on EPAs National Priorities List.

Carl Vest, PhD, is a founding member and Research Director for the South Hill Historical Society.