Bentley's Garment Care, Neodesha, Kansas

State Coalition for Remediation of Drycleaners Site Profiles

Description
Historical activity that resulted in contamination.

Contamination associated with the facility was identified in 1996 during groundwater investigation activities associated with the former BP/Amoco Refinery, located approximately 0.5 miles west of the site. In May 1997, Kansas Department of Health and Environment (KDHE) conducted Site Reconnaissance and Evaluation (SRE) of the site. Analysis of the groundwater samples collected during the SRE indicated presence of tetrachloroethylene (PCE) and trichloroethylene (TCE) at concentrations above the EPA maximum contaminant level (MCL). Expanded Site Assessment, conducted in 2001, identified a contaminant plume approximately 1000 feet downgradient of the facility. From late 2003 to early 2004, a groundwater treatment system was installed at the site to treat groundwater impacted by chlorinated solvents. Bentley's Garment Care operated as drycleaning facility. Land use in the vicinity of the site is primarily residential, with Neodesha City pool and Neodesha High School located to the south and southwest of the site, respectively.

Remediation Status: In active remediation

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

Contaminant	Media	Concentration (ppb)
methylene chloride	soil
Tetrachloroethene (PCE)	groundwater	770 ppb
Tetrachloroethene (PCE)	soil
Trichloroethene (TCE)	groundwater	43 ppb
Trichloroethene (TCE)	soil
1,2-Dichloroethene	soil

Site Hydrology

Deepest Significant Groundwater Contamination:		20ft bgs
Plume Size:		Plume Length: 800ft Plume Width: 500ft Plume Thickness: 5ft
Average Depth to Groundwater:		10ft

Lithology and Subsurface Geology

		Clay Depth: 0-12ft bgs 12ft thick Conductivity: 150ft/day Gradient: 0.002ft/ft
		Sandy clay grading to clayey sand Depth: 12-20ft bgs 8ft thick
		Siltstone bedrock Depth: 20ft bgs

Pathways and DNAPL Presence

Groundwater

Sediments

Soil

DNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?		No
Has a vapor mitigation system been installed?		No

Remediation Scenario

Cleanup Goals:		Reduce the contaminant concentrations of PCE and TCE below the MCLs in groundwater.
Remedy Level:		Full Scale Remedy

Technologies

Ex Situ Air Stripping

Why the technology was selected:
A used Multi-Phased Diffused Bubble Aeration System (MDBAS) was available free of charge from KDHE LUST Program. Groundwater aquifer thickness of 5-10 ft provided easy plume capture for this plume containment system. One-pass trenching system contractor was in the region, and the technology allowed safe installation of a trench collection system in the vicinity of a pool and mature trees. Mobilization charge was significantly cheaper than normal. System was needed to ensure PCE contamination was not "pulled" under the nearby high school due to the petroleum site's pump & treat system remediation wells on the opposite side of the school.

Date implemented:
March 2004: Groundwater Capture/Treatment Oct. to Nov. 2009: Soil Removal

Final remediation design:
The remediation system consists of an interception trench with a horizontal well connected to a sump to allow better capture of the contaminant plume. Contaminated groundwater in the trench is pumped to the on-site remediation system and flows through a series of chambers in the MDBAS. Air is injected into these chambers resulting in the stripping of the contaminants. A vacuum is applied to the chamber and pulls the vapors out through a GAC vapor treatment system. The treated water flows out of the system into an existing sanitary sewer. The entire system is monitored with a Sensaphone 2000 autodialer system. Source/soil removal was undertaken within and below the building in 2009. Soil with PCE concentrations up to 1,400,000 ug/kg was excavated for off-site disposal.

Results to date:
Initially 15% operation efficiency (time) due to improper installation. After KDHE completed system revisions, PCE removal efficiency was up to 98.9%by December 2005. -Influent up to 200 µg/L -Effluent < 5 ug/L

Next Steps:
Semi-annual monitoring and O&M will continue at this site. Source area removal should speed up overall remediation.

Cost to Design and Implement:
Groundwater capture/treatment $134,119 Source Area Removal $200,000

Ex Situ Pump and Treat

Date implemented:
March 2004: Groundwater Capture/Treatment Oct. to Nov. 2009: Soil Removal

Next Steps:
Semi-annual monitoring and O&M will continue at this site. Source area removal should speed up overall remediation.

Cost to Design and Implement:
Groundwater capture/treatment $134,119 Source Area Removal $200,000

Ex Situ Soil Removal

Date implemented:
March 2004: Groundwater Capture/Treatment Oct. to Nov. 2009: Soil Removal

Next Steps:
Semi-annual monitoring and O&M will continue at this site. Source area removal should speed up overall remediation.

Cost to Design and Implement:
Groundwater capture/treatment $134,119 Source Area Removal $200,000

Costs

Cost for Assessment:		$27,291
Cost for Operation and Maintenance:		$56,671
Total Costs for Cleanup:

Lessons Learned

1. Interceptor trench installation using the Dewind one-pass trencher was ideal for this site due to close proximity of trench between a city pool and mature trees.
2. KDHE coordinates pump rates and operation with consultants for a nearby BP/Amoco refinery remediation system to ensure their petroleum plume and the drycleaning plume do not migrate under Neodesha High School, which is directly between the two plumes.
3. Used equipment helped reduce equipment costs.
4. Automatic sequestering agent metering system was important to reduce labor time for system upkeep (weekly visits cut back to monthly).
5. Coordination with City of Neodesha management provided a tremedous working relationship that helped defray costs associated with tree trimming, soil stockpiling, etc. City also helps with minor oversight of the system and calls when problems are encountered.