
West Side Fire Station
January 2017 – June 2018
Management Response:
We appreciate the work done by Internal Audit to review the conceptual cost estimate of this project and
to increase their understanding of construction cost estimation practices. As with any of the airport capital
projects, our cost estimates evolve with more knowledge as we proceed through development of design
and detailed sponsor and stakeholder requirements to the engineers’ estimate used as the basis of
getting construction bids from prospective contractors. We have just updated the estimate based on the
60% design recently submitted by our designer to the Port for review.
Based on our experience with construction cost estimation and construction costs at Sea-Tac airport, we
believe that the design development allowance, construction contingency, and project contingency were
appropriate at the conceptual cost estimate level (i.e., prior to start of design) that was the subject of this
audit and now at the 60% level. Our cost estimates are either developed or reviewed by our cost
estimating manager, who has over 25 years of cost estimation experience for a variety of owners and
contractors.
As for opportunities to improve our processes, we are continuously seeking to improve our processes, the
most significant of which require working with the many sponsors, stakeholders and project delivery
partners involved in doing projects at the airport. We have employed LEAN in the past in these efforts and
will likely do so again.
Allowances - Design Development - $513,000 (30%)
Scope development throughout planning and design is accounted for via Design Development Allowance
(DDA). We include a (DDA) ranging from 20% to 30% at the conceptual planning stage of a project. The
higher range was used because the project is located within the Airfield Operating Area and there were
numerous risks and unknowns. RS Means lists several factors that should be added to the project cost,
including but not limited to dust protection, security requirements, and job conditions. The DDA is reduced
as the project scope is further defined and the design enhanced. We reduce the DDA at each major
design phase and it is removed from the engineer’s estimate when the project goes out to bids for
construction contractors.
At 60%, the DDA has been reduced to 15%. This is the direct result of having more detailed drawings.
However, the direct costs for mechanical, electrical, and sitework have increased. This is mainly due to
power having to come from a further location, increased fencing requirements, additional plumbing
fixtures in the apparatus bays, and communication room needs. These were not anticipated during the
initial conceptual level of the project, especially the power (it was previously anticipated to come from the
much closer Paccar building). The overall project is now estimated to be approximately $5.8M. As we
work towards 100% design, anticipated mid-November 2018, DDA will be reduced to 0% and the
estimate further refined. If the project’s final defined scope cannot be accommodated for the current
budget of $5.5M, the project will request additional funding.
South Satellite Structural Improvement Project - Example
Another example of the evolution of DDA is from our South Satellite Structural Improvement Project.
During the notebook development, DDA was 30%. As is typical at this early stage in the project, as-built
drawings and some site investigations were performed, but significant concerns regarding access to
structural framing, working within operational constraints, and the amount of asbestos to be abated
remained.