Revised On: Feb. 15, 2024 - 12:30 p.m.

Formerly Used Defense Site (FUDS) Project No. J09AZ0412-01

Location

Kingman, Arizona, on the northwest side of Route 66 approximately 3.5 miles northeast of the Route 66-Interstate 40 interchange, in the southwest section of the Former Kingman Ground-to-Ground Gunnery Range. Currently, the site is almost entirely developed for residential purposes. Residential streets within the site include North Tommie Drive, East Lass, East Snavely, East Thompson, East Lum, East Ryan, East Hearne, East Devlin, East Schaeffer, East John and East Northfield avenues. The properties located south of Thompson Avenue are part of a subdivision developed in 1964 called New Kingman. North of Thompson Avenue, Chaparral Mesa II subdivision began development in 2004. In the northeastern section of the site, additional development is currently underway in Long Mountain subdivision.

Contaminants of Concern

Polycyclic Aromatic Hydrocarbons (PAHs), lead, copper, zinc, and antimony, as a result of World War II-era clay pigeon (skeet-shooting) and shotgun projectile debris.

Affected Media

Soil

Public Health Impact

PAHs, and metals (particularly lead) may present health hazards to humans and wildlife through exposure by ingestion, skin contact or inhalation.

Action Taken

Site Inspection: The United States Army Corps of Engineers (USACE) completed a Site Inspection (SI) in September 2011 to evaluate the site for evidence of munitions and explosives of concern, munitions debris and munitions constituents, and to determine whether the site warranted further evaluation under the Comprehensive Environmental Response, Compensation and Liability Act (also known as CERCLA or Superfund). The SI evaluation included a visual inspection along a meandering path of approximately 33.6 miles and the collection of 65 surface soil samples for laboratory analysis. Based on the SI results, the USACE concluded that no explosive hazards remained at the site and recommended conducting a Remedial Investigation/Feasibility Study (RI/FS) to evaluate the extent of clay pigeon debris and soil contamination. In addition, the USACE recommended an expedited evaluation of a removal action for clay pigeon debris in the area of the site identified as Munitions Response Site (MRS) 03 – 15 Skeet Ranges.

Time-Critical Removal Action: As a result of the SI findings, the USACE performed a Time-Critical Removal Action (TCRA) in two phases to remediate visible clay pigeon debris associated with elevated PAH concentrations in the near-surface soils. The primary objective of the TCRA was to immediately remove the higher PAH-concentrated areas at the most affected residential properties within the site to below Arizona residential Soil Remediation Levels, thus directly reducing the associated potential for human health concerns. The USACE completed the TCRA Phase I in April and May of 2013 and Phase II between October 2013 and July 2014.

PAH-impacted soil from 55 properties was excavated to a depth of 2 feet below ground surface and transported off-site for proper disposal. At the completion of excavation activities, the USACE collected confirmation soil samples to verify the impacted soil down to 2 feet below ground surface had been removed from each property. A mesh fence was placed on the bottom of the excavation to identify the depth where the excavation ended. The excavated areas were subsequently backfilled with clean fill material, compacted and covered with new landscaping gravel. 

Remedial Investigation: Since completion of the TCRA, the USACE has continued to perform RI activities in a phased approach at the remaining residential and non-residential parcels at the site. The goal of the RI is to determine the full nature and extent of clay pigeon fragments and soil potentially impacted with PAHs and metals.

The USACE and its contractor investigated 66 residential parcels between December 2014 and February 2017. An additional 60 parcels were investigated between January and October 2019. Between January 2020 and April 2021, the USACE conducted investigations at 30 additional parcels and the public easement along Thompson Avenue. The RI activities include a visual reconnaissance to evaluate the properties for the presence of clay pigeon fragments on the surface and collection of surface and subsurface soil samples for analysis of PAHs and metals. The USACE is also investigating the vertical depth clay pigeon fragments occuring in the subsurface at the site as part of the RI.

The USACE completed a Human Health Risk Assessment to evaluate the risk of exposure to COCs in soil at each of the parcels investigated during the RI. To date, 79 parcels have been identified with a cancer-causing risk factor greater than the acceptable residential exposure level in the zero to one-foot soil sample interval. The highest exposure level was associated with the easement along Thompson Road. The Thompson Easement also exceeded the acceptable noncancer-causing risk level.

Status

The USACE is currently continuing RI activities to complete an evaluation of the nature and extent of contamination. The focus of the ongoing RI is determining the expanse of the impacted area as the boundary has been expanded out. To date, the USACE submitted the Final RI Report documenting the results of the initial RI activities (2014 – 2019) and a Final RI Addendum Report to document the investigation activities conducted at 30 additional parcels and one easement area (2020 – 2021). The USACE will continue to investigate residential parcels bordering those investigated, as well as TCRA parcels where clay pigeon fragments persist. The results of the investigation will be provided in additional RI Addendum Reports. While completing the RI activities, the USACE is working on the FS to determine and present the future remedy options for cleanup at the site. Currently, the USACE anticipates the completion of the FS in Late Summer 2022.