Drycleaner Site Profiles

Former Cowboy Cleaners, Broomfield, Colorado

Description
Historical activity that resulted in contamination.

A site investigation revealed the presence of soil and groundwater contamination, with a groundwater plume covering approximately 1.5 acres. The remediation was handled under the Colorado Voluntary Cleanup Program. The plume occupied portions of five separately owned properties and crossed a street. Small portions of the plume also flowed beneath a retail building and a residence.

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


Contaminant Media Concentration (ppb) Nondetect
Tetrachloroethene (PCE) groundwater 1,900 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:  
Plume Size:  
Average Depth to Groundwater:   25ft

Lithology and Subsurface Geology

 
  Stiff clay to silty to sometimes sandy clay
Depth: 3-8ft bgs
5ft thick
 
  sandy clay
Depth: 8ft bgs

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
checkDNAPL Present

Remediation Scenario

Cleanup Goals:
  Cleanup goals were not identified.

Technologies

In Situ Chemical Oxidation
 

Date implemented:
September 2001

Final remediation design:
A system of 12 nested injectors was installed in the source area. Semi-permanent injectors manufactured using 1-inch PVC screen and riser were installed to allow the controlled injection of permanganate reagent directly into the area of contamination. Each injector was installed with a sand pack to just above the screen, and grouted to the surface. Upon setting of the grout, a charge of permanganate was pressure injected into each injector. A 10% (by weight) solution of permanganate was introduced into each injector, with as much volume as each injector would take, to a maximum of 100 gallons. The injectors were then connected to each other in ranks, and to a head tank by PVC piping. The gravity feeding to all of the injectors on a continuous basis was then started. Up to 300 gallons per day of 1-2% solution were fed into the system during remediation. Most of the injectors were completely above the water table to avoid drainage of reagent directly into groundwater without extensive soil contact. To control PCE that was mobilized into groundwater from the soil source area, a line of injectors was installed dowm stream. These injectors were operated at very low volumes and controlled based on the results of a monitoring well immediate downgradient.

Results to date:
In the source area, PCE concentration started at 1,900 µg/L. One month into the remediation process, PCE concentration had dropped to 926 µg/L and contunue to decrease further to 284 µg/L three monthe after initiation of the remedy. Post-remediation PCE concentration, monitored 8 months later, was found to be 48 µg/L. Downgradient PCE concentrations decreased from 40 µg/L to 15 µg/L within a year.

Next Steps:
In February 2003, the State of Colorado issued a No Action Determination Approval, stating that the property could be used for commercial purposes, and did not pose an unacceptable risk to human health and the environment.

Costs

Cost for Assessment:
 
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
  This was a voluntary cleanup action and cost information was not available.

Contacts

James H. Viellenave
ESN Rocky Mountain
303-278-1911
jviellenave@esn-rm.com

Mark Walker
Colorado Department of Public Health and Environment
303-692-3449
mark.walker@state.co.us

Site Specific References

Viellenave,J.H., et.al., "Using Risk Based Cleanup goals for an In-Situ Chemical Oxidation of PCE in Vadose Zone Soils Under a Voluntary Cleanup Program." Paper presented at IPEC 2002. On-Line address: http://ipec.utulsa.edu/Conf2002/viellenave_lauer_fontana_66.pdf.