Case Study - Fielder Plaza Site, Arlington, Texas

Case Study - Fielder Plaza Site,
Arlington, Texas
Remedy Standard Selection and Presumptive
Remedy Screening
• Richard Scharlach. . P.G.
• Technical Specialist
• Texas Commission on
Environmental Quality
N
o
v
SCRD November 2009
November 19, 2009

Case Study - Fielder Plaza - Outline
• Site Location and History
• Site Assessment Results
• Regional and Site Geology
• Texas Risk Reduction Program (TRRP)
• Groundwater Classification and Remedy
Standards
• Goals for FY2010
SCRD November 2009

Fielder Plaza Site – Arlington Texas
• Arlington is located in Tarrant County.
• Suburban Dallas / Fort Worth area
SCRD November 2009

Aerial View of Fielder Plaza and
Surrounding Area
SCRD November 2009

Fielder Plaza Results of Receptor
Survey
SCRD November 2009

Aerial View of Fielder Plaza
Shopping Center
SCRD November 2009

Fielder Plaza - Site History
• Two former Perc-using Dry Cleaner facilities
-Oak Cleaners /fmr Comet 1 Hr. ( operated1975 –
2004)
-Val-U Cleaners ( operated 1992 – 2005)
• Both are now operating as drop stations.
SCRD November 2009

Fielder Plaza Shopping Center –
Two Former Dry Cleaner Locations
SCRD November 2009

Fielder Plaza - Site History (Cont’d)
• Extensive Site Assessment History (15 years)
• Groundwater assessment completed
• Soil Contamination only at the Comet 1 Hr.
/Oak Cleaners
• Only Tetrachloroethylene (PCE) and
Trichloroethylene (TCE) detected
• One Source or Two
SCRD November 2009

Fielder Plaza -Soil Data
Chemicals of Concern
(COCs)
Greatest
Concentration
Observed (mg/Kg)
Depth
(ft.)
Boring/Well
Observed
Sample
Date
Tetrachloroethylene
(PCE)
57.3
4
B-1
8/2/1999
Trichloroethylene (TCE)
3.01
3-4
B-2
8/2/1999
Cis-1,2
1,2-
dichloroethylene

Fielder Plaza – Soil Data Points
SCRD November 2009

Fielder Plaza - Groundwater Data
Chemicals of
Concern (COCs)
GW GW ING PCL
(mg/L)
Greatest
Concentration
Observed (mg/L)
Well Observed
Date Observed
Tetrachloroethylene
(PCE)
0.005
0.447
MW-14S
12/19/2000
Trichloroethylene
(TCE)
0.005
0.0055
MW-9
6/30/2008
Cis-1,2
1,2-
dichloroethylene
0.07
0.0013
MW-27
1/8/2008
Trans-1,2
1,2-
dichloroethylene
0.1

GroundWater PCLE Excedence
Zone
SCRD November 2009

Regional Geology
• Site Geologic Setting:
Top 0 – 10 feet is Navo-Urban loam and clay soils.
Surface soils are underlain by the outcrop of the
Woodbine Formation, which ranges in thickness
from 200 to 250 feet regionally.
The Woodbine aquifer is a minor aquifer of Texas,
which was once a historic water supply source for
the City of Arlington.
SCRD November 2009

Regional Geologic Map
SCRD November 2009

Fielder Plaza - Cross Section Location
SCRD November 2009

Site Cross Section
SCRD November 2009

Texas Risk Reduction Program
Ground Water Classification and Remedy Standards
TRRP Groundwater
Classification
Class 1 Primary Resource
Class 2 Potential Resource
Class 3 Non-Potential Resource
Definition*
-Impact to PWS possible,
-GW unit is only reliable source
< 800 ft bgs
-High yield and low TDS
-Moderate yield and TDS
Low Yield or High TDS
Groundwater Cleanup
Level
Drinking Water Standards
Drinking Water Standards.
Plume Management Zone
(PMZ) Allowed.
100xDrinking Water Standards.
PMZ allowed.
Not a Groundwater-Bearing
Unit
K < 1 x 10-
-5 cm/sec
K < 1 x 10
cm/sec
Drinking Water Standards do
not apply.
SCRD November 2009

TRRP Groundwater Classification
at Fielder Plaza (Woodbine Aquifer)
• TRRP Groundwater Class 2
• Basis for Groundwater Classification
• Water Quantity: Well Yield 5,000 to 25,000 gpd.
• Water Quality: TDS

TRRP GW Classification and
Remedy Standards at Fielder Plaza
TRRP Groundwater
Classification
Class 1 Primary Resource
Class 2 Potential
Resource
Class 3 Non-Potential
Resource
Definition*
-Impact to PWS possible,
-GW unit is only reliable source <
800 ft bgs
-High yield and low TDS
-Moderate yield and
TDS
Low Yield or High TDS
Groundwater Cleanup
Level
Drinking Water Standards
Drinking Water
Standards
Plume Management
Zone (PMZ) Allowed
100xDrinking Water Standards.
PMZ allowed
Not a Groundwater-Bearing
Unit
Hydaulic Conductivity < 1 x 10
cm/sec
Conductivity < 1 x 10-
-5
SCRD November 2009
Drinking Water Standard do not
apply.

TRRP Remedy Standards Options
• Remedy Standard A –
Decontamination.
Cleanup to Drinking Water Standards
• Remedy Standard B - Closure with
Controls.
Controls. (e.g. Engineered Caps, Land Use
Restrictions, Plume Management Zone PMZ)
SCRD November 2009

Plume Management Zone (PMZ)
Plume Management Zone – a defined area and
depth interval within which institutional controls
are applied to prevent human contact with
affected groundwater. This effectively removes
the groundwater ingestion pathway from
consideration inside the PMZ.
SCRD November 2009

Plume Management Zones – What’s
Required
•Detailed Requirements for Implementation
of a PMZ
•Maximum Allowable Size of a PMZ
•Must be a Contingency Plan in place to
implement addition response actions if plume
is expanding.
SCRD November 2009

TRRP Remedy Standards Options at
• Remedy Standard A:
Fielder Plaza
‣ Cleanup Entire Plume to Drinking Water Standards
• Remedy Standard B:
‣ Establish PMZ for Entire Plume
‣ Establish PMZ for Onsite Portion of Plume and
Cleanup Offsite Portion of Plume to Drinking Water
Standards
SCRD November 2009

Plume Management Zone – Option 1
SCRD November 2009

Plume Management Zone – Option 2
• Include PMZ map with only half of plume in
PMZ
SCRD November 2009

Is Remediation Required if PMZ is
Implemented
• Even if PMZ is implemented – soil and
groundwater remediation will still be required.
SCRD November 2009

Fielder Plaza - Presumptive Soil
Remedy Options
• In-Situ Chemical Oxidation
• Excavation
• Soil Vapor Extraction
SCRD November 2009

Soil Remedy Options – removed
from consideration
• In-Situ Chemical Oxidation and
Excavation are
are removed from consideration
since most of the affected soils are beneath the
occupied building.
SCRD November 2009

Soil Remedies Selected
• Soil Vapor Extraction:
SVE remediation is recommended at this site
based upon:
• The relatively high permeablility soils (sandy clay
/ fine sand)
SCRD November 2009

Presumptive
Ground Water Remedy Options
• Long Term Monitoring (required for PMZ)
• Bioremediation / Biostimulation
• Permeable Reactive Barriers
• Pump & Treat
SCRD November 2009

Groundwater Remedies – Long
Term Monitoring
• Long-term Monitoring:
Given the relatively large plume and low concentrations of PCE
in groundwater samples, the designation of a Plume
Management Zone (PMZ) and the continued long-term
monitoring of the groundwater are warranted.
SCRD November 2009

Groundwater Remedies –
Bioremediation / Biostimulation
• Bioremediation/Biostimulation
Biostimulation: Based on the
geochemical profiling ( pH, Redox Potential, Dissolved
Oxygen, etc.), the groundwater for this site is not favorable
for natural biodegradation,
• However, the reducing conditions of the aquifer can
possibly be made favorable through Biostimulation.
• Pilot Test Planned for FY10 – Injection of polylactate
biostimulant upgradient of Val-U Cleaners.
SCRD November 2009

Groundwater Remedies –
Contingencies
• Permeable Reactive Barriers (PRBs(
PRBs):
): Could be employed to
mitigate and impede migration of contaminant plumes to the adjacent downgradient
residential area.
• Pump and Treat: As a hydraulic control option
As a hydraulic control option or alternatively, a
extracted groundwater could be extracted, amended with low cost
biostimulants, and re-injected into the formation through an infiltration
trench.
SCRD November 2009

Next Steps – Goals for FY10
• GW Sampling
Perform periodic sampling for COCs and MNA parameters at existing and
new monitoring wells.
• SVE Pilot Testing
For Soil Contamination, conduct pilot test to evaluate the effectiveness and
scalability of SVE for the site.
• Bio-Stimulation Pilot Testing
For Groundwater Contamination, conduct pilot test using HRC-X, and
evaluate long-term influence to down gradient groundwater.
• Sentinel Well Needed
Well #28 will be used to evaluate potential plume migration towards a nearby
residential pond.
SCRD November 2009