DSHW-2018-004847 - 0901a06880831435

Virgilio Cocianni
Remediation Manager
Schlumberger Technology Corporation
121 Industrial Boulevard
Sugar Land, TX 77478
Tel: [phone]
May 25, 2018
MAY 2 9 2018
VA4W-2100-004e17
Div of Waste Management
and Radlation Control
Schlumberger
Mr. Rolf Johnsson
Utah Department of Environmental Quality
Waste Management and Radiation Control
195 North 1950 West
Salt Lake City, UT 84116
Subject: Up-Hydraulic-Gradient Contamination
Former Dowell Schlumberger Facility, Vernal, Utah
UTD092026657
Dear Mr. Johnsson:
This letter is in response to a question in the February 21, 2018, approval letter for the Second
Semiannual Monitoring Results-2017,1 dated January 30, 2018. The division indicated in that
letter that it was unable to find a referenced document titled Remediation Approach, Former
Dowell Schlumberger Facility, Vernal, Utah, dated September 16, 2014 or its approval and
requested a copy of the document.
The document in question was presented to the Division as a PowerPoint presentation to provide
an update on site activities and a path forward for site remediation. A pdf of the document is
attached. It was reported in this presentation (along with other pertinent information) that while
tetrachloroethene (PCE) contamination in the northern part of the site appeared to be related to
onsite soil contamination, PCE in the southern portion of the site appeared to come from an
offsite, upgradient source. This determination was based on the analysis of samples and water
level elevations collected from temporary monitoring wells located along 135 S Street, located
south and west of the site. Concentrations of PCE in these wells appeared to increase to the west.
Since groundwater has been consistently observed to flow across this site from west to east,
these results suggested that a source of PCE contamination appeared to be located west of the
site and that contaminants from this source impact the southern portion of the site. This
presentation and subsequent reports interpret this source as impacting groundwater
contamination south of the former source area onsite referred to in the enclosed presentation as
"Tool Shop" and also referred to historically as the "Tool Shed".
1 CH2M HILL Engineers, Inc. (CH2M). 2018. Second Semiannual Monitoring Results-2017 Former Dowell
Schlumberger Facility, Vernal, Utah. Prepared for Schlumberger Technology Corporation and The Dow Chemical
Company. January.
Mr. Rolf Johnsson
May 25, 2018
Page 2
Data used in the Remediation Approach presentation were included in the Site Remediation Plan2
(SRP), dated October 2015. The offsite sources are discussed in detail in Section 3.4, Offsite PCE
Source Assessment. The SRP was approved by the Utah Department of Environmental Quality
on March 9, 2016. We take the approval of the SRP by the Division as being the formal
concurrence of the conclusion contained within the SRP that the impacts in the southern portion
of the site are due to offsite sources.
We will begin quarterly groundwater monitoring, as was approved by the Division, so we can
close the groundwater remedy.
If you have questions or comments, please call me at 281-285-4747. I can also be reached by
e-mail at cocianni-vslb.com.
Sincerely,
Virgilio Cocianni
Remediation Manager
Enclosures
• Attachment 1. Remediation Approach (September 16, 2014)
c: Jim Strunk/The Dow Chemical Company
Terence Mares/CH2M HILL Engineers, Inc.
Monica Schneider/CH2M HILL Engineers, Inc.
Dave Urann//CH2M HILL Engineers, Inc.
2 CH2M HILL Engineers, Inc. (CH2M). 2016. Site Remediation Plan Former Dowell Schlumberger Facility, Vernal, Utah. Prepared for Schlumberger Technology Corporation and The Dow Chemical Company. October.
Attachment 1
Remediation Approach
(September 16, 2014)
Schlumberger
Remediation Approach
Former Dowell Schlumberger Facility
Vernal, Utah
September 16, 2014
Presented to the Utah Department of Environmental Quality
4110 CH2IVIHILL.
Health & Safety Message - OFFICE TRAPS Schlumberger
An accident in the office can be just as painful and costly as an accident in the field.
• Falls are the most common office accident, accounting for the greatest number of disabling
injuries. In fact, office workers are twice as likely to suffer a fall as non-office workers.
• There are many different reasons why employees fall while on the job. They could fall while walking,
climbing ladders and stairs, and even while sitting in chairs. People can trip over telephone and electrical cords, open desk and file drawers, loose or worn carpeting and rugs, debris, and equipment and packages
left in aisles "just for a moment."
• Strains and back injuries from improper lifting, unexpected twisting, jerking or overexertion
often disable office workers.
• Learn and follow proper lifting techniques and always get help with heavy or awkward loads.
• Office fires can be as deadly and job-consuming as facility blazes.
• Know your nearest fire escape route, and where and how to use or activate the fire alarm system and firefighting equipment.
Office safety is everyone's responsibility.
Organization of Presentation ScMumherger
• Review of Site History and Background
• Land Use and Other Site Considerations
Nature and Extent of Contaminants of Concern
Proposed Remedial Action Objectives (RA0s)
Remedial Goals to Accomplish RAOs
• Remediation Approach and Conceptual Design
• Proposed Path Forward
Site Assessment: soil gas
survey identified UST west of
truck shop that leaked
petroleum hydrocarbons
(removed in 1989) and UST
near tool shop containing
chlorinated hydrocarbons,
PAHs, and phthalate (removed
in 1992). Groundwater
monitoring wells installed.
Consent
Agreement
with UDEQ Site
remodeled
Dowell
Schlumberger
constructs site
and begins
oilfield support
services from
the site
1962 1978-1981 1989 1993 1995 201.3
Implementation
of SVE system
near tool shop.
Test pit
excavated soil
containing
petroleum
hydrocarbons
east of truck
shop
Oil field
operations
cease;
CH2M HILL
conducts site
characterization
to delineate soil
and
groundwater
contamination
Review of Site History and Background
Land Use and Other Site Considerations Schlumherpr
• Land is currently zoned industrial and is unoccupied.
• The Vernal General Plan indicates future land use will remain industrial.
• The nearest surface water body is Ashley Creek approximately 0.75 miles east
(downgradient).
• Other industrial properties bound the site: see the map on the following slide.
Site Location Map Schluderger
FAST MAIN FFT
' .
m Amodio, .
RCTTIF ,770,e1TRUCTSOfkl vARt,
EK.TUIPMEN R !CRAG & AREA
Nature and Extent of COCs
• Contaminants of Concern (COCs) have been identified in soil and in groundwater.
• These COCs were identified based upon exceedences of applicable EPA screening
levels based upon land use:
Soil Groundwater
Industrial Soil Regional Screening Level
(RSL)

Maximum Contaminant Level (MCL)

MCL-based protection of groundwater
(DAF=20 for unsaturated soil)
Nature and Extent of COCs in Soil: Protection of Groundwater Schlumberger
50 100 meters
Soil Boring and Sampling Location (November 2013)
Soil Boring and Sampling Location (August 2014)
Contour of PCE Concentration in Soil Above
MCL-Based Migration to Groundwater
Screening Level (0.046 mg/kg with EPA Default
Dilution Attenuation Factor of 20); Dashed Where inferred
Soil concentrations exCeeding the migration to groundwater screening level are shown next to the locations of exceedance
• The COC present in groundwater above the MCL is PCE.
• Areas of PCE in soil above the EPA MCL-based soil migration to groundwater RSL are shown
in the above figure.
Nature and Extent of COCs: Soil Direct Exposure ScMuntherger
0 50 meters 100
°°
+ Soil Boring and Sampling Location (November 2013)
Soil Boring and Sampling Location (August 2014)
Ethylbenzene in Soil
Above Industrial Screening Level of 25 mg/kg
(Sample Concentration Noted)
Arsenic in Soil Above Industrial Screening Level
of 3 mg/kg (Sample Concentration Noted)
• One small area/volume of ethylbenzene slightly above the industrial RSL: maximum concentration of
28.1 mg/kg and industrial RSL = 25.0 mg/kg (May 2014 EPA RSL Table).
Arsenic detected up to 38.4 mg/kg, but within EPA acceptable target cancer risk range of 1 x 10-6 to
1 x 10-4.
Schlumberger Soil Risk Evaluation
Area of PCE above
migration to groundwater
screening level Area of ethylbenzene
above industrial screening
level
o Risk evaluation performed to assess risk associated with ethylbenzene in soil:
- Cancer risk estimate is approximately 1 x 10-6 , equal to the lower end of the EPA's acceptable target risk range (10-6 to 10-4) and does not exceed the target threshold.
- Area of ethylbenzene exceedance is small. The exposure point concentration would be significantly lower than the maximum detected concentration because:
o The frequency of ethylbenzene detections in tool shop samples is low.
o Many of the detected concentrations are lower than the industrial soil RSL.
- Area of ethylbenzene above industrial screening level is within area of PCE above migration to groundwater screening level, which is planned for treatment (discussed subsequently).
o Conclusion: Remediation to specifically address soil contact risk not required.
Schlumberger Nature and Extent of COCs: Groundwater
925-2
10
100
a.
Jan-89 Sep-02 May-16
1 3an-89 Jun-94 Dec-99 Jun-05 Nov-10 May-16 NOTES TCE exceeds the MCL gr the two southern Incahons where ireTcated
100
P r). • t , ,
1
3an-89 Sep-02 May-16
El Groundwater Sarroltng Location-HydroPunt
PCE Concentrator) ro Groundwater MCL of 5 u
Concentrations Nloted Betow Each Location
COM& al Water Table Devotion
(Feet Above Mean Sea LeW)
925-6
1000
1
925-18
MCL
Two areas exceeding MCL for PCE of 5 µg/L: northern and southeastern.
Maximum concentration in north = 37.8 mg/L (March 2014).
Statistically significant (at 95% confidence level) evidence of decreasing concentrations at each area.
Groundwater along Southern Border
meters 50 I DO
di Groundwater Samplirig Location-Monitoring Well
El) Groundwater Sampling Location-HydroPunch
PCE Concentration in Groundwater > MCL of 5 ug/L
Concentrations Noted Below Each Location
Contour of Water Table Elevation
(Feet Above Mean Sea Level)
0
11.2
NOTES " TCE exceeds the MCL in the tvvo southern locations where indicated
• PCE in groundwater along the southern boundary does not appear to be related to Dowell Schlumberger
activities:
- August 2014 water levels and groundwater samples indicate highest concentrations off-property
and up hydraulic gradient (note the location of the 41.2 11g/L result).
Soil
RAO 1: Mitigate migration of
contaminants to groundwater
Groundwater
RAO 1: Prevent potential future
human exposure to contamination
above remedial goals (RGs)
through contact with or ingestion of
contaminated groundwater
RAO 2: Remediate site-related PCE
concentrations in groundwater to
the MCL
Proposed Remedial Action Objectives and
Remediation Goals Sch!wiener

•Remedial Action Objections:
•Remedial Goals:
—Soil: Remediate soil with PCE concentrations greater than migration to groundwater
screening level (0.046 mg/kg with DAF = 20).
—Groundwater: Remediate groundwater with site-related PCE concentrations greater than
the MCL.
Remediation Approach
• Inject permanganate into the vadose zone of the treatment areas (as delineated by
the red box) and allow to drift downgradient upon reaching the water table.
-Comprises a comprehensive remedy that addresses PCE both in groundwater (see time
series from monitoring well 925-6) and low levels in soil that may be migrating to groundwater.
-Would accelerate the already declining PCE trend in groundwater.
Schlumberger Remecliation Conceptual Design
• Implement ISCO Injection using Permanganate
- Assumed radius of influence of 15 feet: approximately 48 direct push injections:
• —40 in Truck Shop area; —8 in Tool Shop area
2 injection events.
In Truck Shop area within the building, saw cut and remove concrete to allow for repeated treatment or
addition of water to flush through the vadose zone as needed.
Path Forward Schlumberger
• Obtain approval to decommission SVE system (requested in Site
Characterization Report, May 2014).
• Obtain approval of the Sampling and Analysis Plan (submitted May 2014).
• Submit a Remedial Action Plan.
• Implement remedial actions as agreed upon by UDEQ.
• Remediation performance monitoring (as appropriate).
• Upon achievement of remediation goals, apply for a Certificate of Closure.
• Contamination along the southern border (135 South Street) is not related to
Dowell operations.