Drycleaner Site Profiles

Former American Cleaners - Arnold Park Mall, Arnold, Missouri

Historical activity that resulted in contamination.

American Cleaners operated at the Arnold Park strip mall for over 25 years. The strip mall is located at the intersection of Highway 141 and Jeffco Boulevard north of Arnold. The drycleaners is no longer in operation, but the site/area is still a strip mall.

Remediation Status: Site closed

Contaminants present and the highest amount detected in both soil and groundwater.

Contaminant Media Concentration (ppb) Nondetect
chloroform groundwater 8.2 ppb
cis-1,2-Dichloroethene groundwater 3,790 ppb
cis-1,2-Dichloroethene soil 230 ppb
Tetrachloroethene (PCE) groundwater 6,150 ppb
Tetrachloroethene (PCE) soil 310 ppb
Trichloroethene (TCE) groundwater 814 ppb
Trichloroethene (TCE) soil 175 ppb
toluene soil 7 ppb
trans-1,2-Dichloroethene groundwater 814 ppb
trans-1,2-Dichloroethene soil 6.6 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   29ft bgs
Plume Size:  
Average Depth to Groundwater:   22.5ft

Lithology and Subsurface Geology

  Silty clay, clay and stiff clay with chert fragments

Pathways and DNAPL Presence

DNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
How was the site evaluated?
  Groundwater sampling,Compared sample concentration to screening criteria
Results of VI evaluation:
  A completed VI pathway has been indentified
Has a vapor mitigation system been installed?
Additional VI Information:
  For the indoor inhalation pathway, the representative concentration for PCE was calculated and determined to be below the residential levels.

Remediation Scenario

Cleanup Goals:
  Drinking Water Pathway: acetone, 2.97 mg/L; trans 1,2-DCE, 0.1 mg/L; cis 1,2-DCE, 0.07 mg/L; chloroform, 0.08 mg/L; PCE, 0.005 mg/L; TCE, 0.005 mg/L; toluene, 1.0 mg/L

Inhalation Pathway from Groundwater: acetone, 101,000 mg/L; trans 1,2-DCE, 1.78 mg/L; cis 1,2-DCE, 19.4 mg/L; chloroform, 0.814 mg/L; PCE, 1.95 mg/L; TCE, 4.49 mg/L; toluene, 117 mg/L

Inhalation Pathway from Subsurface Soil: acetone, 143,000 mg/L; trans 1,2-DCE, 8.62 mg/L; cis 1,2-DCE, 7.01 mg/L; chloroform, 0.310 mg/L; PCE, 2.14 mg/L; TCE, 5.04 mg/L; toluene, 140 mg/L


In Situ Monitored Natural Attenuation

Final remediation design:
Based upon the present development of the site, its present zoning for a shopping center, and the nature of the surrounding developments, it was assumed that the property would remain commercial or non-residential in the future. Nevertheless, the concentration of the contaminants present were compared to applicable residential cleanup target values, in order to close the site without restrictions as to future use or activity.

Results to date:
The maximum levels of contamination in the groundwater were above the Tier 1 residential levels for the indoor inhalation pathway and the domestic water use pathway. For the indoor inhalation pathway, the representative concentration for PCE was calculated and determined to be below the residential levels. The groundwater was monitored for four quarters beginning in 2004. The source of the contamination was no longer present (i.e., drycleaning facility) and the groundwater plume was stable with decreasing contaminant levels and a risk assessment was subsequently conducted. The domestic water-use pathway was determined to be incomplete based on a "weight of evidence" evaluation that included the following: · The Public Water Supply District No. 1 serves the site and surrounding area. · The City of Arnold's City Code effectively limits the installation of private water supply wells by requiring water distribution systems to be connected to a public water supply if available. · There are no known public water supply wells within one mile of the site or known private water supply wells within one-quarter mile of the site. However, there may be isolated instances of continued use of private water supply wells in the Arnold urban area. · Missouri's Well Construction Code requires domestic wells in Area 1 (which encompasses all of Jefferson County) to have at least 80 ft of casing extending not less than 30 ft into un-weathered bedrock. This would prevent use of the shallow strata most likely to be impacted by the contamination from being used a source of domestic water supply. A Certification of Completion was subsequently issued.

Next Steps:
Site is closed.


Cost for Assessment:
  Not available
Cost for Operation and Maintenance:
Total Costs for Cleanup:


Scott Huckstep
Missouri Department of Natural Resources Brownfields/Voluntary Cleanup Program
(573) 526-2740

Participant's Consultant:
Shifrin @ Associates
Walter G. Shifrin, President