Drycleaner Site Profiles

Former Alpine Cleaners, Friendswood, Texas

Description
Historical activity that resulted in contamination.

Alpine Cleaners operated as a PCE drycleaner from 1989 to 1998. A sewer line break was reportedly one of the pathways for contaminant migration into the subsurface. Spills at the facility and discharges to a storm sewer were also identified as possible source areas.

Remediation Status: In groundwater monitoring


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


Contaminant Media Concentration (ppb) Nondetect
Benzene groundwater
cis-1,2-Dichloroethene groundwater
1,1-Dichloroethene groundwater
Tetrachloroethene (PCE) groundwater
Trichloroethene (TCE) groundwater
trans-1,2-Dichloroethene groundwater
Vinyl Chloride groundwater
1,2-Dichloroethene groundwater

Site Hydrology

Deepest Significant Groundwater Contamination:   16ft bgs
Plume Size:   Plume Width: 50ft
Average Depth to Groundwater:   10ft

Lithology and Subsurface Geology

 
  Silty clay
Depth: 0-12.5ft bgs
12.5ft thick
Conductivity: 0.283ft/day
Gradient: 0.0055ft/ft
 
  fine-grained clayey sand
Depth: 12.5ft bgs

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
checkPresumptive Evidence of DNAPL

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
  No
Has a vapor mitigation system been installed?
  No 
Additional VI Information:
  None available to date.

Remediation Scenario

Cleanup Goals:
  PCE = 5 Ug/l; TCE = 5Ug/l; cis 1,2-DCE = 70Ug/l;
Goals: vinyl chloride = 2Ug/l

The remediation focus in the 2009 Chem-ox injections were to clean up a "hot spot" on site.

Technologies

In Situ Chemical Oxidation
 

Why the technology was selected:
Based on bench scale testing, in-situ chemical oxidation was selected.

Date implemented:
1999 (1 event), 2001 (1 event), 2009 (2 events)

Final remediation design:
In 1999, there were two five-day injection events utilizing hydrogen peroxide, in three injection wells. The volume of treated groundwater was estimated to be approximately 17,000 gallons. Initially, an aqueous solution of ferrous sulfate and hydrochloric acid and finally by a 35% solution of hydrogen peroxide (495 gallons in the first event and 605 gallons in the second injection event). In August and September of 2001, a total of 135 gallons of a 5.5% solution of potassium permanganate was injected at the site. In May and July of 2009, 2 events occurred where 360 pounds (lbs) of RegenOX oxidant was mixed with 500 gallon of potable water to form a 5 % solution and then injected into the ground during each event. The injection target goal was 20 feet below ground surface.

Other technologies used:
N/A

Results to date:
*The 1999-2001 In-situ chemical oxidation events resulted in only minor reductions in chlorinated solvent concentrations. Since those events, the source area and plume have been better characterized. The size and concentration of the plume are greater than was thought when the remediation events were conducted. Groundwater analytical results in 2007 indicated concentrations of PCE and its daughter products exceeding Tier 1 PCLs in the samples collected from wells MW-1 and MW-6. Daughter products exceeding their Tier 1 PCLs included TCE, cis- and trans-1,2-DCE, 1,1-dichloroethene (1,1-DCE), and vinyl chloride. The highest concentration of PCE (8.1 mg/L) and its daughter products were reported in well MW-6. *Groundwater analytical results in 2008 continue to indicate concentrations of PCE and its daughter products exceeding Tier 1 PCLs. PCE, TCE, Cis-1,2-DCE, Trans-1,2-DCE, and 1,1-DCE have shown an increase in concentrations since last sampled in December, 2007, with vinyl chloride showing the only decrease in concentration. The increase in daughter products indicates that reductive dechlorination continues to occur at the site. *2012: None of the treatments have been sucessful in the long term. The likely causes of the failed remedial actions include site hydrogeology and the design of the Chemical oxidation injection events was not dense enough.

Next Steps:
* In 2006, this site transfered from an RP-lead program to a state lead program. * Continue Monitoring of existing monitor wells to obtain additional groundwater data and evaluate any trends. * Investigation of second groundwater unit is ongoing. *In 2009, a pilot study will evaluate the applicability and/or effectiveness of in-situ chemical oxidation (ISCO) with regards to the site s geologic conditions and in terms of the reduction of chlorinated solvent contaminant concentrations currently above TRRP Tier 1 PCLs in the shallow groundwater bearing unit. As part of the study, a sodium percarbonate based chemical oxidant will be injected into the subsurface to treat COCs. This oxidant will be utilized in the study because it will exist in the subsurface over a longer period than the previously injected oxidant. *There was a FY10 Biotrap feasibility study to conduct if a particular type of bioremediation will be more feasible on site. The recommendations from this study concluded the biostimulation and bioaugmenation together is a suitable treatment for the containment source area ("hot spot"). There has been no further remedial actions or studies on this site beyond groundwater mointoring and further assessments of the contaminent source.

Costs

Cost for Assessment:
 
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
  $56,858 (1999 and 2001) + $43,085 (2009 events) = $99,943

Lessons Learned

*Source area should be fully characterized before conducting remediation.

*A review of data results from the October 1999 response action showed concentration reductions, with later site data showing a return of concentration levels. Based on soil types at the site (silty clay to silty sand), it appeared that the delivery system may not have been adequate to provide a sufficient radius of coverage. In addition, hydrogen peroxide based oxidants are fast acting oxidants, reducing the overall area of influence, that require a lower pH concentration, which is not typical of the site. Although a pH adjustor was included, the site pH is not generally compatible with the oxidant and the overall effectiveness may have been reduced.

*Additional injections at closer injection spacings were recommended in order to reduce the contaminant concentrations; due to site geology, a dense injection pattern will be required to effectively treat the contaminated area. Data also suggests that COCs may have been accelerated by the injection of large volumes of liquid during ISCO pilot tests (2009 events). Enhanced bioremediation was originally proposed (never implemented),and it is said that it should have been implemented at that time because it is more practical and cost effective compared to the ISCO's on the site.

Contacts

Richard Scharlach
Texas Commission on Environmental Quality(TCEQ)
Dry Cleaners Remediation Program (DCRP)12100 Park Circle, Bldg.D
Austin, Texas 78753