8c. Memo

Former United Continental Tank Site Closure

COMMISSION 
AGENDA MEMORANDUM                        Item No.          8c 
ACTION ITEM                            Date of Meeting      October 25, 2022 

DATE :     September 7, 2022 
TO:        Stephen P. Metruck, Executive Director 
FROM:    Megan King, Interim Senior Manager, Aviation Environment & Sustainability 
Sarah Cox, Director Aviation Environment & Sustainability 
SUBJECT:  Former United Continental Tank Farm Site Funding and Agreement Amendment for
Site Closure 
Amount of this request:                          $78,505 (included in ERL Forecast) 
Total estimated Port cost to date:                                          $639,576 
ACTION REQUESTED 
Request Commission authorization for the Executive Director to execute a Sixth Amendment to
the Participation Agreement (Amendment) for Cleanup of Sea-Tac International Airport Jet Fuel
Facility executed in November 1995 between the Port, United Airlines, Continental Airlines, and
Olympic Pipeline Company (Participants). 
EXECUTIVE SUMMARY
The Former United/Continental Fuel Farm Site (Site) is located south of the Fire Station on Air
Cargo Road near gate E-100. Subsurface jet fuel contamination was encountered at the Site
during closure of the tank farms in the 1990s. Following identification of contamination, the
parties (United as the lead responsible party, Continental which is now also United, Olympic
Pipeline, and the Port) entered into a Participation Agreement for investigation and remediation
of the Site. 
Remedial activities at the Site are complete, and the parties agree that independent closure, as
allowed by the Model Toxics Control Act, is the best path forward. 
This Participation Agreement Amendment adds funds to the project escrow account to cover
costs of system decommissioning, and long-term responsibility language for contamination
remaining in place at the Site. Work will consist of removal of the remaining treatment system
infrastructure including all subsurface piping and monitoring wells and restoration of the Site.
The Port’s 21% share of remedial costs (share percentages were determined in the original
Participation Agreement) for this Amendment will be $78,505. No ongoing monitoring or actions
are anticipated following completion of Site closure activities. 

Template revised January 10, 2019.

            COMMISSION AGENDA – Action Item No. 8c                                  Page 2 of 4
Meeting Date: October 25, 2022 

JUSTIFICATION
Remediation of the Site has removed all recoverable product, and groundwater impacts have
reduced in concentration and extent. The Participation Agreement requires decommissioning
and removal of the remediation equipment once it is no longer necessary. Additional funding is
now required in the project escrow account for system decommissioning and removal, which
requires modification to the existing Participation Agreement to cover this issue and address
future responsibility for any contamination remaining in place following Site closure. 
Diversity in Contracting 
Not applicable to this request. 
DETAILS 
Investigation and remediation at the Site has been in progress since 1995 and consisted of active
in-situ  remediation  by  dual-phase  and  soil  vapor  extraction  processes.  The  remediation
successfully removed recoverable product from the subsurface, and in 2017 the remediation
system was shutdown. After some monitoring was conducted, the Site was enrolled in Ecology’s
Voluntary Cleanup Program and a No Further Action opinion was requested from the Department
of Ecology in March 2019. In 2021, additional data were collected. These data confirmed that the
product remaining in the subsurface is not transmissive (doesn’t move) and therefore cannot be
recovered, and the groundwater data confirmed that the concentrations and extent of
contamination remaining in groundwater beneath  the site are decreasing  due to natural
attenuation. 
Ecology has communicated that it does not need the Participants to undertake further action at
the Site.  Accordingly, in early August, the Participants submitted a letter to Ecology formally
removing the Site from Ecology’s Voluntary Cleanup Program. The letter notifies Ecology that Site
cleanup has been conducted as an Independent Cleanup Action, as allowed by the Washington
state Model Toxics Control Act. This letter also describes how the Port will implement
Institutional Controls at the property for future protection of human health and the environment
that consist of: 
• maintaining the Site as zoned for Airport Operational uses 
• restricting access to the area through maintenance of the existing facility fencing and
signage 
• controlling future contact with remaining contamination during actions that disturb the
subsurface through implementation of the Port’s Rules for Airport Construction, and 
• restricting groundwater extraction at the Site. 
Scope of Work
Site Closure Activities funded by Amendment 6 will consist of:
(1)   Removal of remediation system and supporting infrastructure 

Template revised June 27, 2019 (Diversity in Contracting).

            COMMISSION AGENDA – Action Item No. 8c                                  Page 3 of 4
Meeting Date: October 25, 2022 
(2)   In-place decommissioning of the groundwater monitoring well network 
(3)   Removal of Tank Farm infrastructure components left in place during decommissioning
due to the presence of contamination (concrete and sheetpile wall segments).
Schedule
On authorization, work will be scheduled as soon as possible, with the goal of completing work
before Summer 2023. 
ALTERNATIVES AND IMPLICATIONS CONSIDERED 
The following alternatives were considered: 
Alternative 1 – Partial removal of remediation system infrastructure by other construction teams
as part of future capital projects in the area of the Site. 
Cost Implications: $78,000+ plus additional Port effort for removal, coordination, and cost
recovery 
Pros:
(1)   Does  not  require  a  separate  mobilization  for  removal  of  the  treatment  system
infrastructure. 
(2)   Allows for removal of only system components that conflict with previously approved
future development actions. 
Cons:
(1)   Places burden of system removal on capital project teams to estimate, track and
conduct. 
(2)   Capital project contractors may not have specialized skills or equipment to remove the
remediation system infrastructure and introduces unnecessary complexity to capital
development efforts.
(3)   Requires separation and cost tracking of remediation system removal by the capital
projects, and cost recovery following completion. 
This is not the recommended alternative. 
Alternative 2 – Hire specialized contractor to completely remove the remediation system 
infrastructure ahead of any capital projects in the vicinity of the Site, in accordance with the
existing participation agreement. 
Cost Implications: 
Pros:
(1)   Completes remediation requirements scoped in the Participation Agreement. 
(2)   Allows  for  costs  to  be  split  between  the  remediation  parties  according  to  the
established percentages. 
(3)   Does not require cost recovery following completion. 

Template revised June 27, 2019 (Diversity in Contracting).

            COMMISSION AGENDA – Action Item No. 8c                                  Page 4 of 4
Meeting Date: October 25, 2022 
Cons:
(1)   No limitations identified for this alternative. 
This is the recommended alternative. 
FINANCIAL IMPLICATIONS 
Annual Budget Status and Source of Funds 
This work will be funded by a project escrow account setup by the Participants. The Port’s share
of costs will be deposited to the escrow account from ERL funds. No additional costs are
anticipated for this Site. 
ATTACHMENTS TO THIS REQUEST 
(1)   Presentation slides 
(2)   Draft Sixth Amendment 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS 
July  2014  –  The  Commission  authorized  execution  of  the  Fifth  Amendment  to  the
Participation Agreement 
2013 – The Commission authorized execution of the First Addendum to the Fourth
Amendment to the Participation Agreement 
March 2009 – The Commission authorized execution of the Fourth Amendment to the
Participation Agreement 
August 2001 – The Commission authorized execution of the Third Amendment to the
Participation Agreement 
January 1997 – The Commission authorized execution of the Second Amendment to the
Participation Agreement 
1996 – The Commission authorized execution of the First Amendment to the Participation
Agreement 
1995 – The Commission authorized execution of the Original Participation Agreement 






Template revised June 27, 2019 (Diversity in Contracting).



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