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ATTACHMENT 5:
PROJECT NARRATIVE
425-869-2670 ■ 15325 SE 30th Place, Suite 300 ■ Bellevue, Washington 98007 ■ www.dowl.com
Scope of Work:
The Windsock Apron and 243 Building Apron and Parking Lot Rehabilitation Project includes
the preparation of final plans, contract documents, Construction Safety and Phasing Plan
(CSPP), Engineer’s Design Memo and cost estimates, in addition to support through the bidding
process, and construction management for the project elements described below:
Airport Improvement Program (AIP) Eligible Work:
• There is no AIP eligible work on this project.
Non-AIP Eligible Work:
• Apron Pavement Rehabilitation - The full depth pavement reconstruction of the windsock
and 243 building aprons.
• Replacement of Aircraft Tiedown Anchors – Removal of existing tiedown anchors at the
windsock and 243 building aprons and new anchors will be designed to secure small
aircrafts.
• 243 Building Parking Lot Reconfiguration – The removal and reconfiguration of the
existing 243 building parking lot.
• Vehicle Gate V7 Relocation – The relocation of the existing Vehicle Gate V7 at the 243
Building, the existing chain-link fence, and all associated equipment.
Bid Schedules:
This project will be bid with two non-eligible bid schedules as follows:
• Schedule A – Windsock Apron Rehabilitation
• Schedule B – 243 Building Apron and Parking Lot Rehabilitation
Existing Site Conditions:
The Renton Municipal Airport is zoned as Industrial Medium. The proposed work will not change
the zoning designation. Both the windsock apron and 243 building apron and parking lot were
constructed prior to 1985 and there seems to be no improvements to the pavement section
since it was initially constructed. Currently, both apron areas are used for lighter GA aircraft
parking. The 243 building also provides parking for airport personnel and visitors.
HWA conducted a geotechnical investigation at the Renton Municipal Airport in August of 2023.
The investigation consisted of seven geotechnical borings and seven core samples. The results
of the explorations indicate the presence of soft to very soft, fine-grained soils, including layers
of peat and organic silt that will likely require stabilization before new pavement is constructed.
The topography of the site is relatively flat with slopes ranging from 1% to 3%. The site is largely
developed and is generally covered in asphalt or concrete with some landscaped areas.
Runoff from the windsock apron is collected in catch basins and either outfalls directly into the
Cedar River or is detained in an onsite detention pond before outfalling into the Cedar River.
Runoff from the 243-building apron and parking lot is collected in catch basins and is routed to
an offsite conveyance pipe which routes runoff north and eventually outfalls into Lake
Washington.
DATE: July 22, 2024
SUBJECT: Renton Aprons – Project Narrative
MEMORANDUM
Page 2 of 2
Proposed Design:
Total project area covers roughly 2.7 acres at Renton Municipal Airport. All improvements will
occur on the Renton Municipal Airport property. No off-site improvements are proposed. Access
is established from E Perimeter Rd and W Perimeter Rd, and no new utility connections are
required.
The proposed pavement section will consist of four-inches of asphalt pavement which is
underlain with six-inches of crushed aggregate base course and eight-inches of subbase
course. This pavement section exceeds what is initially present at the site (per the Geotechnical
Report in Appendix E) and is therefore deemed to be a sufficient depth to hold small aircrafts.
This project will apply two coats of new paint markings to the reconstruction apron. New
markings will include 6-inch wide yellow taxiway centerline markings and 4-inch wide white
tiedown and parking stall markings. All new markings will comply with FAA AC 150/5340-1M,
Standards for Airport Markings. No temporary markings will be used for this project.
Because this is a rehabilitation project, net earthwork quantities are small. This project will have
approximately 45.69 cubic yards of net fill. Fill material will consist of subbase course under the
reconstructed pavement section to slightly raise grade, classified as P-154 by FAA.
No trees will be removed as part of this project.
Estimated Project Costs:
DOWL estimates a total project cost of $1,750,000, all of which is not AIP eligible.
Special Site Features:
The Windsock Apron is adjacent to (within 200 feet of) the Cedar River and its floodplain area.
The Cedar River is classified as a Shoreline of Statewide Significance. The shoreline of the
Cedar River is best described as a steep cutbank of a meandering river. This project is entirely
outside of and will not interact with the floodplain area. The site does not contain any wetlands,
water bodies, steep slopes, or other special site features – The vertical elevation of the project
is insignificant and no views will be obstructed by the proposed project.