Drycleaner Site Profiles

Morningstar Cleaners, Houston, Texas

Description
Historical activity that resulted in contamination.

Active dry cleaning facility located in a commercial shopping center. This property enrolled in TCEQ in 2007. The use of PCE as the dry cleaning solvent was discontinued in 2009. Investigations have included the installation of 14 groundwater monitoring wells into the shallow groundwater bearing unit (GWBU), and five monitor wells into the second GWBU. There is a shallow groundwater plume centered on site beneath the dry cleaning facility; however, concentrations above PCL have been detected off-site in an adjacent residential neighborhood.

Remediation Status: In groundwater monitoring


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


Contaminant Media Concentration (ppb) Nondetect
trans-1,2-Dichloroethene groundwater 3.5 ppb
cis-1,2-Dichloroethene groundwater 280 ppb
Tetrachloroethene (PCE) groundwater 2,700 ppb
Trichloroethene (TCE) groundwater 120 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   24ft bgs
Plume Size:   Plume Length: 300ft
Plume Width: 200ft
Plume Thickness: 30ft
Average Depth to Groundwater:   34ft

Lithology and Subsurface Geology

 
  Sandy clay then clayey sand
Depth: 0-20ft bgs
20ft thick
Gradient: 0.001ft/ft
 
  Wet, fine-grained sand (first GWBU).
Depth: 20-30ft bgs
10ft thick
Gradient: 0.001ft/ft
 
  Sandy clay on either side of a stratum of very stiff (reddish brown) clay
Depth: 30-45ft bgs
15ft thick
Gradient: 0.001ft/ft
 
  Second GWBU (clayey sand)
Depth: 45-57ft bgs
12ft thick
Gradient: 0.001ft/ft
 
  Red, stiff clay
Depth: 57ft bgs
Gradient: 0.001ft/ft

Pathways and DNAPL Presence

checkGroundwater
Sediments
Soil
DNAPL Present

Vapor Intrusion Pathway

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

Remediation Scenario

Cleanup Goals:
  GWBU 2 is classified as a class 3 low yield unit. The existing COCs do not exceed class 3 PCLs, therefore no response action is required at this time.

For the first GWBU: reduce COC levels below MCLs.
Remedy Level:
  Interim Action

Technologies

In Situ Bioremediation
 

Why the technology was selected:
In-situ bio-augmentation followed by monitored natural attenuation was chosen because it provided for the degradation of the COCs through cometabolism with minimal disruption to on-going site activities. The groundwater plume is generally centered on-site beneath the dry cleaner facility. Therefore, excavation was not a viable option.

Date implemented:
May 2011

Final remediation design:
FY2011: in-sito bio-augmentation follwed by MNA. 300 gallons of facultative bacteria and nutrients mixed with clean water were injected under pressure into the shallow GWBU. The bioremediation product used was Cl-Out. The injections were performed through 25 temporary injection points placed around the periphery of the facility in the areas of highest concentrations. The injection points were advanced using direct push methods on a grid of approximately 20 feet.

FY2012: Additiional in-situ bio-augmentation events were completed. Cl-Out was injected int o the shallow GWBU through temporary injection points advanced by a direct push rig.

Results to date:
Reductions of 30 to 90 percent PCE concentrations have occured. Analytical results of the current groundwater monitoring and sampling show decreasing concentrations of COCs across the source area within the first GWBU. The decreasing trends can be attributed to a combination of in-situ bio-augmentation events completed at the site in FYs 2011 and 2012 and the on-going natural attentuation response actions.
As a result of the degradation of PCE, concentrations of the daughter products (TCE and cis-1,2-DCE) have increased in some of the monitoring wells. Concentrations of VC remain below the laboratory detection limits in first GWBU monitoring wells indicationg that complete dechlorination of the COCs are occuring.
Monitoring wells in the second GWBU indicate that present COC levels do not exceed the class 3 groundwater ingestion pathway PCLS. Therefore, a response action is not required at this time.

Next Steps:
Continued response action with an emphasis on maintaining dissolved oxygen level above 1.0 mg/L. The increase in biological activity in the plume source area has decreased dissolved oxygen to concentrations generally less than 1.0 mg/L, which indicate anaerobic conditions. As the groundwater becomes anaerobic, the CI-Out bacteria will begin to die as the naturally occuring bacteria begin to dominate, resulting in an incomplete degredation pathway and the accumulation of PCE daughter products.

Cost to Design and Implement:
$102,758.52

In Situ Monitored Natural Attenuation
 

Why the technology was selected:
In-situ bio-augmentation followed by monitored natural attenuation was chosen because it provided for the degradation of the COCs through cometabolism with minimal disruption to on-going site activities. The groundwater plume is generally centered on-site beneath the dry cleaner facility. Therefore, excavation was not a viable option.

Date implemented:
May 2011

Final remediation design:
FY2011: in-sito bio-augmentation follwed by MNA. 300 gallons of facultative bacteria and nutrients mixed with clean water were injected under pressure into the shallow GWBU. The bioremediation product used was Cl-Out. The injections were performed through 25 temporary injection points placed around the periphery of the facility in the areas of highest concentrations. The injection points were advanced using direct push methods on a grid of approximately 20 feet.

FY2012: Additiional in-situ bio-augmentation events were completed. Cl-Out was injected int o the shallow GWBU through temporary injection points advanced by a direct push rig.

Results to date:
Reductions of 30 to 90 percent PCE concentrations have occured. Analytical results of the current groundwater monitoring and sampling show decreasing concentrations of COCs across the source area within the first GWBU. The decreasing trends can be attributed to a combination of in-situ bio-augmentation events completed at the site in FYs 2011 and 2012 and the on-going natural attentuation response actions.
As a result of the degradation of PCE, concentrations of the daughter products (TCE and cis-1,2-DCE) have increased in some of the monitoring wells. Concentrations of VC remain below the laboratory detection limits in first GWBU monitoring wells indicationg that complete dechlorination of the COCs are occuring.
Monitoring wells in the second GWBU indicate that present COC levels do not exceed the class 3 groundwater ingestion pathway PCLS. Therefore, a response action is not required at this time.

Next Steps:
Continued response action with an emphasis on maintaining dissolved oxygen level above 1.0 mg/L. The increase in biological activity in the plume source area has decreased dissolved oxygen to concentrations generally less than 1.0 mg/L, which indicate anaerobic conditions. As the groundwater becomes anaerobic, the CI-Out bacteria will begin to die as the naturally occuring bacteria begin to dominate, resulting in an incomplete degredation pathway and the accumulation of PCE daughter products.

Cost to Design and Implement:
$102,758.52

Costs

Cost for Assessment:
  $178,228.86
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
 

Lessons Learned

I learned that rebound occurs of PCE daughter products as PCE and TCE get degraded. I would use this at another site and figure out site-specific parameters to tailor the technology to that site. The system is continually being improved.

Contacts

David Cullen
Project Manager
Texas Commission on Environmental Quality
PST/DCRP Section, Remediation Division, MC-137
P.O. Box 13087
Austin, TX 78711-3087
512-239-4137
David.Cullen@tceq.texas.gov

Site Specific References

Monitoring Event Summary and Status Report 2013
Sampling Event Summary and Status Report 2011
Affected Property Assessment Report