Superfund Site: LOWRY LANDFILL
Superfund Site Profile
CAG Scoping Meeting
Thursday, September 21, 2017
Vista Peaks Exploratory School
24511 E. 1st Ave.
Aurora, CO 80018
Fourth Five Year Review in Progress: Section 121 of the Comprehensive Environmental Response, Compensation and Liability Act of 1980 requires remedial actions that result in any hazardous substances, pollutants, or contaminants remaining at the site be subject to a five-year review. The purpose of the five-year review is to evaluate the implementation and performance of the remedy to determine whether the remedy is protective of human health and the environment.
The fourth five-year review for the site is currently underway. A public notice was made in the Denver Post Newspaper on October 20, 2016, announcing the beginning of the review and inviting the public to submit any comments related to the site to EPA. The planned completion date of the fourth five-year review is no later than September 30, 2017. Upon completion, the report will be posted here in the Publicly Available Documents collection and made available at the site’s public information repository.
The Lowry Landfill site is located on 507-acres in western Arapahoe County, Colorado, about two miles east of the city of Aurora. From the mid-1960s until 1980, the city and county of Denver operated “co-disposal” landfill at the site, accepting liquid and solid municipal and industrial wastes, including sewage sludge disposed of in unlined pits or land application. In 1980, Waste Management of Colorado, Inc. (WMC) took over operation of the landfill. At that time, waste disposal on site was restricted to municipal waste and later asbestos waste. Municipal solid waste disposal activities ceased in 1990 and a 4-foot soil cover was installed over the landfill unit. Asbestos disposal is ongoing northeast of the landfill. Landfilling operations contaminated soil, groundwater, surface water and sediment with hazardous chemicals. Additionally, gases from buried wastes contaminated the air space in subsurface soils. EPA estimates about 138 million gallons of industrial wastes were disposed of at the landfill.
The Denver Arapahoe Disposal Site (DADS), an operating municipal solid waste landfill, forms the northern and eastern boundaries of the site. Denver is the sole owner of the DADS parcels. Off site, solid waste disposal operations are expected to continue at DADS for the next several decades. Land use in the general area surrounding the site is changing, with new and planned residential communities located west and north of the site and DADS. Road expansions for Gun Club Road and East Quincy Avenue (the southern boundary of the site) have been proposed for the near future.
The site is located within the Murphy Creek drainage system. Murphy Creek is located immediately east of the site. An unnamed tributary to Murphy Creek is present on the site which is dry and only contains water during significant precipitation or snow melt events. This unnamed tributary extends from the toe of the landfill through the northern portion of the site. Groundwater occurs in two major systems each (with two aquifer zones) and include shallow groundwater (Alluvium/Weathered Dawson and Unweathered Dawson) and deep groundwater (lignite layer and Upper Denver). The lower Unweathered Dawson formation is separated from the Upper Denver by a lignite layer.
Groundwater flow within the shallow and deep systems is predominantly to the north, although the shallow groundwater system also shows components of flow to the east, west and south. Groundwater rights on site and immediately off site are owned by Denver and use is restricted to monitoring or remediation purposes only.
1,4-dioxane was not identified as a contaminant of concern prior to 2002. Once identified as a potential contaminant of concern, analysis was performed to determine if this chemical was present in groundwater. EPA classifies 1,4-dioxane as an emerging contaminant due to renewed interest in evaluating and investigating potential impacts, as new techniques for testing have become available. Two private residential wells are located about one-mile north of the site and are sampled on an annual basis. To date, no site-related contaminants have been observed in either of the residential monitoring wells.