HomeMy WebLinkAboutC_DOE VCP Letter for Vapor Barrier Study_201005.pdfOctober 1, 2020
Dale Walker
D + C Investments, LLC
555 SW Grady Way
Renton, WA 98057
(dwalker@walkersrenton.com)
Re: Opinion pursuant to WAC 173-340-515(5) on Remedial Action for the following
Hazardous Waste Site:
•Site Name: South End Auto
•Site Address: 3400 E Valley Road, Renton, WA 98057
•Facility/Site No.: 27793456
•Cleanup Site ID: 14715
•VCP Project No.: NW3233
Dear Dale Walker:
The Washington State Department of Ecology (Ecology) received your request for an opinion on
the Vapor Intrusion Assessment (VI Report) dated July 9, 2020 regarding the South End Auto
facility (Site). This letter provides our opinion. We are providing this opinion under the
authority of the Model Toxics Control Act (MTCA), Chapter 70.105D RCW.
Issue Presented and Opinion
Does the proposed VI Report meet the stated objectives with respect to assessing the VI exposure
pathway?
YES. Ecology has determined that the VI Report assessed the VI exposure pathway
in accordance with Ecology VI guidance, and provides documentation that VI
exposure to future building occupants is unlikely. However, the results of the single
sampling event described in the VI Report need to be supplemented with additional
sampling prior to and upon occupation of the new building, to document the
absence of VI impacts.
Description of the Site
This opinion applies only to the Site described below. The Site is defined by the nature and
extent of contamination associated with the following releases:
Electronic Copy
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October 1, 2020
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• Total petroleum hydrocarbons in the gasoline, diesel and oil range (TPH-G, TPH-D and
TPH-O), benzene, toluene, ethylbenzene and xylenes (BTEX), cadmium, chromium, arsenic,
lead, zinc, nickel, polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs),
tetrachloroethene (PCE), trichloroethene (TCE), 2-butanone (MEK), acetone and
dichlorodifluoromethane into the Soil.
• TPH-G, TPH-D, TPH-O, benzene, toluene, PAHs, vinyl chloride, barium, cadmium,
chromium, arsenic, copper, nickel, zinc and lead into the Groundwater.
• Air-phase hydrocarbons, benzene, naphthalene, 1,3-butadiene, chloroform, and acrolein in
Soil Vapor.
Enclosure A includes diagram of the Site, showing the sample locations described in the VI
Report.
Please note a parcel of real property can be affected by multiple sites. At this time, we have no
information that the parcel(s) associated with this Site are affected by other sites.
Basis for the Opinion
This opinion is based on the information contained in the documents listed in Enclosure B.
A number of these documents are accessible in electronic form from the Site web page[1]. The
complete records are kept in the Central Files of the Northwest Regional Office of Ecology
(NWRO) for review by appointment only. Visit our Public Records Request page [2] to submit a
public records request or get more information about the process. If you require assistance with
this process, you may contact the Public Records Officer at publicrecordsofficer@ecy.wa.gov or
360-407-6040.
This opinion is void if any of the information contained in those documents is materially false or
misleading.
Analysis and Opinion
Based on a review of the VI Report, Ecology has determined:
• The sampling methods and results presented in the VI Report are consistent with Ecology
VI guidance and application of associated screening levels from the Ecology CLARC
database.
• Results from the two sub-slab soil vapor samples collected inside the new building on the
Site (currently under construction and not yet occupied) show concentrations of
chemicals of concern (COCs) below Method B sub-slab soil gas screening levels. As
[1] https://apps.ecology.wa.gov/gsp/Sitepage.aspx?csid=14715
[2] https://ecology.wa.gov/publicrecords
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October 1, 2020
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noted in the VI Report, this is likely due to the performance of the engineered vapor
barrier (a passive mitigation system) placed beneath the building slab, and the excavation
of contaminated soil beneath the building footprint prior to construction.
• Ecology concurs that these results indicate exposure of future building occupants to
COCs via the vapor intrusion pathway is unlikely. However, it is Ecology’s opinion that
the data from the single sampling event do not support the statements in the VI Report
that there will be no human exposure risk to people inside the future structure, and that
further evaluation of the VI exposure pathway is unnecessary at the Site.
• In order to confirm the absence of such exposure, Ecology recommends additional
sampling prior to and during initial occupation of the building. This recommendation is
consistent with guidance developed by the US Environmental Protection Agency
(OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway
from Subsurface Vapor Sources to Indoor Air, OSWER Technical Publication 9200.2-
154, June 2015), which is referenced in the Ecology VI guidance. The following are
quotes from the EPA document:
o Section 8.4, page 153: “Passive systems are generally less predictable and less
efficient at preventing vapor intrusion than active systems and, therefore,
typically warrant more intensive monitoring, all else being equal.”
“As with radon mitigation systems (EPA 1993a, Section 11.1.2), results of indoor
air sampling during initial post-construction monitoring may be used to
demonstrate that the occupant’s exposure to vapor-forming subsurface
contaminants has been reduced as anticipated.”
• The following Site-specific factors indicate an ongoing potential for VI impacts, and
support the Ecology recommendation for additional sampling:
o Soil vapor concentrations in three of the four soil vapor probes advanced
immediately adjacent to the new building (see Enclosure A, Diagram of the
Site) showed COC concentrations above sub-slab soil vapor screening levels.
o Concentrations of naphthalene in groundwater samples from monitoring well
MW-5, located beneath the service area of the new building, ranged from 13 to
160 µg/L, above the Method B VI groundwater screening level of 8.9 µg/L.
• Ecology recommends preparation of a VI sampling and analysis plan, to be implemented
as the new building is prepared for occupation, including:
o Install vapor pins in the building floor slab, at a sufficient number of locations to
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October 1, 2020
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confirm the absence of potential VI impacts to future building occupants, in the
areas of the building where they will be working.
o Ecology concurs with the recommendation in the VI Report that a plan be
developed and implemented to repair the perforation in the engineered vapor
barrier, which occurred during collection of the Subslab02 sample. Include a
vapor pin at the Subslab 02 sample location, after the repair has been completed.
o Sample the vapor pins for VI COCs identified in the VI Report, before and after
building occupation.
o Sample indoor air at a sufficient number of locations to assess potential impacts to
future building occupants, in the areas of the building where they will be working.
Collect samples immediately before and after the building has been occupied.
o Apply Ecology and EPA VI guidance in selecting sampling stations, sample
collection methods, quality assurance protocols, and laboratory analytical
methods. Also consider potential effects of the building systems and activities on
sample locations, collection procedures, and interpretation of results. Examples
include automotive chemicals and vehicle exhaust, and operating parameters of
the heating, ventilation, and air conditioning (HVAC) system.
• Continued progress towards a No Further Action opinion for this Site under the VCP will
require resolution of the issues cited in the May 11, 2020 opinion letter from Ecology.
These issues include successful upload of Site data to the Ecology Environmental
Information Management (EIM) database, which has not yet occurred.
Limitations of the Opinion
1. Opinion does not settle liability with the state.
Liable persons are strictly liable, jointly and severally, for all remedial action costs and
for all natural resource damages resulting from the release or releases of hazardous
substances at the Site. This opinion does not:
• Resolve or alter a person’s liability to the state.
• Protect liable persons from contribution claims by third parties.
To settle liability with the state and obtain protection from contribution claims, a person
must enter into a consent decree with Ecology under RCW 70.105D.040(4).
2. Opinion does not constitute a determination of substantial equivalence.
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October 1, 2020
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To recover remedial action costs from other liable persons under MTCA, one must
demonstrate that the action is the substantial equivalent of an Ecology-conducted or
Ecology-supervised action. This opinion does not determine whether the action you
performed is substantially equivalent. Courts make that determination. See RCW
70.105D.080 and WAC 173-340-545.
3. State is immune from liability.
The state, Ecology, and its officers and employees are immune from all liability, and no
cause of action of any nature may arise from any act or omission in providing this
opinion. See RCW 70.105D.030(1)(i).
Contact Information
Thank you for choosing to clean up the Site under the Voluntary Cleanup Program (VCP). After
you have addressed our concerns, you may request another review of your cleanup. Please do
not hesitate to request additional services as your cleanup progresses. We look forward to
working with you.
For more information about the VCP and the cleanup process, please visit our web site:
www.ecy.wa.gov/vcp. If you have any questions about this opinion, please contact me by phone
at (425) 324-1892 (mobile) or e-mail at michael.warfel@ecy.wa.gov.
Sincerely,
Michael R. Warfel, Site Manager
NWRO Toxics Cleanup Program
Enclosures (2): A –Diagram of the Site
B – Basis for the Opinion: List of Documents
cc: Bill Kane, EcoCompliance Corporation, (bill@ecocompliance.biz)
Alex Morganroth, City of Renton, (AMorganroth@Rentonwa.gov)
Enclosure A
Diagram of the Site
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Enclosure B
Basis for the Opinion:
List of Documents
This opinion is based on the information contained in the following documents:
1. EcoCompliance Corporation, Groundwater Sampling Event Round 6, August 25, 2020,
September 10, 2020.
2. Dixon Environmental Services LLC, Vapor Intrusion Assessment, 3400 East Valley
Road, Renton, WA 98057, July 9, 2020.
3. Department of Ecology, VCP Opinion, Response Comments, May 11, 2020.
4. EcoCompliance Corporation, Site Remediation Report (revised), April 10, 2020.
5. EcoCompliance Corporation, Response to Ecology’s Comments on Site Cleanup of
Former South End Auto Property in Renton, April 2, 2020.
6. Department of Ecology, Further Action Opinion Letter, March 25, 2020.
7. EcoCompliance Corporation, Site Remediation Report, November 5, 2019.
8. EcoCompliance Corporation, Groundwater Sampling Event Round 3, September 2019,
October 2, 2019.
9. EcoCompliance Corporation, Revised Site Remediation Work Plan, August 14, 2019.
10. EcoCompliance Corporation, Revised Remedial Investigation (RI) Report, May 10, 2019.
11. Department of Ecology, Initial Investigation Field Report, July 28, 2018.
12. PBS Engineering and Environmental, Inc., Hazardous Materials Survey Report, May 18,
2018.
13. Stemen Environmental, Inc., Remedial and Corrective Actions Project for the
Commercial Property Located at 3400 Valley Road, Renton, Washington, April 23, 2018.
14. Stemen Environmental, Inc., Limited Phase II Environmental Site Assessment,
Groundwater Monitoring Well Installation, and Groundwater Monitoring Informational
Letter for the Commercial Property Located at 3400 East Valley Road, Renton,
Washington, April 23, 2018.
15. Stemen Environmental, Inc., Limited Phase II Environmental Site Assessment for the
Commercial Property Located at 3400 East Valley Road, April 23, 2017.