PORT OF SEATTLE 
MEMORANDUM 
COMMISSION AGENDA             Item No.      6d 
Date of Meeting      4/5/2011 

DATE:    March 18, 2011 
TO:      Tay Yoshitani, Chief Executive Officer 
FROM:    Michael Ehl, Director, Airport Operations 
Wayne Grotheer, Director Aviation Project Management Group 
Elizabeth Leavitt, Director Aviation Planning & Environmental Programs 
SUBJECT: Airfield Stormwater Detention Pond M Modifications  Contract 3
(CIP # C100172) 
Amount of This Request: $ 0           Source of Funds: Airport Development Fund 
State and Local Taxes Paid: $294,000     Jobs Created: 10 
Total Estimated Project Costs: $4,246,000 
ACTION REQUESTED: 
Authorization for the Chief Executive Officer to advertise and execute a construction contract for
the 2011 Stormwater Detention System (SDS) Pond M Modifications and SDS 6/7 Vault Outfall
Structure at the Seattle-Tacoma International Airport in the corrected amount of $4,246,000. 
The corrected amount aligns with the budgeted amount of $4,400,000 that had been reserved for
the remaining Pond M work. The Commission authorized this contract in the amount of
$1,389,000 on March 1, 2011, but the wrong cost estimate was used in determining the total
project cost, necessitating the new contract authorization. No additional budget is requested
since funds are available from previously authorized budget for the Third Runway Project (CIP
#C100172). 
BACKGROUND: 
This memo corrects the total estimated project costs authorized by the Commission in the request
made on March 1, 2011. The amount indicated in that memo was $1,389,000, which was the
estimated amount for the 2010 work on Pond M. The correct amount is $4,246,000. This
amount aligns with the budget amount of $4,400,000 that had been reserved for the remaining
Pond M work. 
The error occurred when the project manager was out of the office for an extended period and
other staff were assigned to prepare the Commission memo. An estimate found in the files was
assumed to be the correct one and used for the costs in the memo. Subsequent discussions
regarding the costs did not reveal the error. To insure future communication breakdowns do not
occur and that all costs are identified, the AV/PMG airfield team is using a formal review

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
March 18, 2011 
Page 2 of 6 
meeting of project estimates that include the key parties that would have knowledge of potential
project costs. 
This authorization will allow construction bids to be obtained for the scope of work under the
overall Third Runway Project. Although the runway is operational, certain projects associated
with the runway must be completed as required by environmental permits and before the overall
project will be complete. No additional budget is being requested. Sufficient budget for this
work within the Third Runway Project has already been authorized by the Commission. This
project will not increase the Airport's forecasted cost per enplanement. The cost of this work is
estimated to be $4,246,000. 
ADDITIONAL BACKGROUND: 
Environmental permits for the Third Runway require the Port to provide stormwater detention
and water quality treatment for the Airport including the new Third Runway and all other Airport
surfaces. These facilities were to be completed before the Third Runway became operational in
November 2008. With the exception of the Pond M modification and an outfall structure for the
SDS 6/7 vault, all facilities including eleven detention ponds and vaults along with a number of
water quality facilities have been completed. In 2008, Port staff requested a delay in
constructing Pond M from the Washington State Department of Ecology (Ecology). This delay
allowed the site to be used for the management of construction site stormwater associated with
Runway 16L reconstruction. Ecology's water quality branch granted the Port a two-year
extension. 
Following this extension, Port staff developed plans with the intent of constructing Pond M in
the summer of 2010. Included in those plans were provisions to install an outfall structure in the
SDS 6/7 stormwater vault. The Commission provided authorization for construction bid
advertisement as part of the Airfield Improvement Project-2 (AIP-2) on January 12, 2010.
Subsequent to that authorization, unforeseen site conditions, particularly unsuitable foundation
soils, were discovered by geotechnical investigations. These conditions necessitated further
analysis and design prior to obtaining a dam safety permit from the Ecology. The additional
analysis and design work, in addition to a restrictive construction schedule window set by
Ecology, necessitated separating the Pond M work from the 2010 contract. Ecology's water
quality branch was notified of the additional design needs and extended the Third Runway's
permit requirements for completing the stormwater facility until the fall of 2011. The
Commission authorized a one-year delay to the construction of Stormwater Detention Pond M on
May 24, 2010, in accordance with Section 4.2.3.3.(ii) of Resolution No. 3605. No additional
project funds are being requested as part of this authorization. The original budget for the 2010
AIP-2, per the January 12, 2010 authorization was $6,625,000. The estimated cost of the Pond
M modifications and SDS 6/7 outfall structure installation is $4,246,000. The additional analysis
and design work did not result in the estimated cost exceeding the budgeted amount for the work. 
PROJECT JUSTIFICATION: 
Pond M is one of several stormwater projects that were required to fulfill Third Runway
environmental permit obligations. Completion of Pond M stormwater detention facility will
satisfy the outstanding permit requirements and in doing so provide flow control and additional

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
March 18, 2011 
Page 3 of 6 
water quality treatment for approximately 160 acres of Airport surfaces draining to Miller Creek.
The existing SDS 6/7 vault has been constructed with an outlet that provides temporary flow
control but does not meet current standards. A new control structure will provide the required
hydraulic controls. 
Project Objectives: 
Convert the existing construction Stormwater Pond M and expand it to a permanent stormwater
detention facility and install a permanent control structure in the SDS 6/7 vault the Airport.
PROJECT SCOPE OF WORK AND SCHEDULE: 
Scope of Work: 
The existing construction stormwater pond will be expanded through the excavation and
construction of a two-celled facility with a final detention capacity of approximately 26 acre-feet.
Each cell will be formed by an earthen berm, constructed to meet dam safety permit
requirements. Underlying soils determined to be unsuitable for the embankment foundation will 
be removed. Conveyance piping spillways, hydraulic control structures, and outfall pipes to
receiving waters will be installed. A heavy plastic liner will be anchored to the inner berm
slopes and netting will be fitted above both cells to reduce the pond's open water attraction to
wildlife. The SDS 6/7 control structure work will entail installing a baffle wall in an existing
manhole with a series of orifices designed to release water at controlled rates in accordance with
current standards. 
Schedule: 
Complete Design   1st Quarter 2011 
Bid and Award    2nd Quarter 2011 
Start Construction   3rd Quarter 2011 
In-Use Date      4th Quarter 2011 
Project Completion  4th Quarter 2011 
FINANCIAL IMPLICATIONS: 
The funds to pay for the Pond M modifications are part of the Third Runway Program budget
previously authorized by the Port Commission. No additional project budget is being requested. 
Budget/Authorization Summary: 
Original Budget                                         $587,362,000 
Budget Additions                                      $541,594,000 
Total Budget                                         $1,128,956,000 
Returned Savings                                      -$130,621,738 
Revised Budget                                       $932,408,802

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
March 18, 2011 
Page 4 of 6 
Previous Authorizations                                   $1,128,956,000 
Current Request for Authorization                                     $0 
Total Authorizations, including this request                       $1,128,956,000 
Remaining Budget to be Authorized                                  $0 
Project Cost Breakdown: 
Construction costs                                          $3,391,000 
Sales tax                                                    $294,000 
Aviation Project Management and other soft costs                     $ 855,000 
Total                                                    $4,246,000 
Budget Status and Source of Funds: 
This project is included in the 2011-15 capital budget and Plan of Finance within the Third
Runway Program (CIP # C100172). The funding source will be the Airport Development Fund.
Financial Analysis and Summary: 
These estimated costs will not cause the total projected costs to exceed the revised budget, and
will not affect cost per enplanement (CPE) as these projects were already included in the CPE
forecast. 
OPERATION & MAINTENANCE IMPLICATIONS: 
O&M costs for Pond M will be comparable to other recently modified storm water ponds. Costs
would include a monthly inspection, a more detailed six month inspection and a yearly cleaning
of the pond. Estimate includes approximately 105 hours of labor per year or approximately
$5,500 to $6,000. 
ENVIRONMENT AND SUSTAINABILITY:
As a condition of the permits issued for the Third Runway Project, rigorous environmental
standards for the quality of the fill material, construction stormwater treatment and air quality
were established. These include requirements to retrofit the existing Airport surfaces and newly
created surfaces to current standards for stormwater runoff flow control and water quality
treatment. These current standards are designed to sustain a healthy aquatic habitat in
downstream receiving waters. Once completed, this project in combination with other
stormwater facilities will reduce erosion in local streams caused by uncontrolled runoff from
impervious surfaces. In addition this facility will provide supplemental water quality treatment
of pollutants associated with Airport operations.
STRATEGIC OBJECTIVES: 
This request supports the Port's Strategic Objective to Exhibit Environmental Stewardship by
meeting required environmental permit obligations.

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
March 18, 2011 
Page 5 of 6 
TRIPLE BOTTOM LINE SUMMARY: 
This action links to the overall completion of the Third Runway Project, which was developed in
an environmentally responsible way and overall is a vital regional transportation facility that
supports economic growth in many ways.
ALTERNATIVES CONSIDERED AND THEIR IMPLICATIONS: 
Option 1  Do Nothing. This option would result in the Port not being in compliance with 
environmental permits and likely result in sanctions being issued by the environmental
regulatory agencies. The existing undersized Pond M would remain in place, potentially
allowing excessive flows to cause erosion in Miller Creek. Discharges from the SDS 6/7 Vault
would not meet current standards specified in the permits. This is not the recommended option. 
Option 2  Modify Pond M and install the SDS 6/7 control structure. This option would result in
the Port fulfilling environmental commitments for stormwater management and provide a
stormwater facility that meets current standards. This is the recommended option. 
OTHER DOCUMENTS ASSOCIATED WITH THIS REQUEST: 
None. 
PREVIOUS COMMISSION ACTION: 
On August 1, 1996, the Commission adopted Port Resolution No. 3212, as Amended, approving
the Master Plan Update for Airport, including development of a new dependent air carrier
runway, and authorizing initial development work for the Runway project. 
On May 27, 1997, the Commission authorized $587,362,000 for completion of the Runway
project to be completed by 2004. 
On June 22, 1999, the Commission authorized an additional $186,000,000, increasing the total
authorization to $773,362,000. At that time, it was estimated permitting would be finalized by
December 1999 and the Runway project would be complete by fall 2006. 
On June 24, 2003, the Commission was briefed on additional costs from delays, permit
conditions, market conditions, scope of project, and FAA requirements. At that time, the
Runway project was scheduled to be completed at the end of 2008. 
On October 11, 2005, the Commission authorized an additional $125,000,000 increasing the total
authorization to $898,362,000. 
On September 26, 2006, the Commission authorized an additional $219,594,000 increasing the
total authorization to $1,128,956,000. 
On April 21, 2009, the Commission authorized the advertisement for construction bids for the
Lora Lake Demolition, Des Moines Nursery Mitigation and the Third Runway Stormwater Pond
Projects. 
On July 28, 2009, the Commission authorized design for Miller Creek Relocation Revisions,
160th Street Culvert Removal, and Third Runway Environmental Mitigation at Seattle-Tacoma
International Airport.

COMMISSION AGENDA 
Tay Yoshitani, Chief Executive Officer 
March 18, 2011 
Page 6 of 6 
On January 12, 2010, the Commission authorized the advertisement for construction bids for
Third Runway Mitigation, including Miller Creek Relocation Revisions and Restoration; 160th 
Street Bridge/Culvert Removal; and Third Runway Permanent Stormwater Detention Facility at
the Airport. 
On June 1, 2010, the Commission authorized the separation of Stormwater Retention Pond M
(Pond M) from the other 2010 Airfield Improvement Projects  Contract 2 (AIP-2) and delay
construction until 2011. 
On March 1, 2011, the Commission authorized the advertisement and execution of a construction
contract for the 2011 Stormwater Detention System (SDS) Pond M Modificatoins and SDS 6/7 
for a total estimated project cost of $1,389,000.