HomeMy WebLinkAbout33_C_Letter of Understanding geological Risk_230925_v1
Date: September 25th, 2023
TO: Andrew Van Gordon
City of Renton, Department of Community & Economic development
RE: Le$er of Understanding Geological Risk
APPLICANT:
Lavina Wadhwani
Dreamliner LLC
10655 NE 4th Street
Bellevue, WA 98005
lavinaw@veerarchitecture.com
SITE INFORMATION:
Parcel Number: 722930-058002
Site Address: 511 Airport Way, Renton, WA
Lot Size: 16,000 square feet (0.37 acres)
Zoning: Commercial Arterial (CA) and Commercial Downtown (CD)
Comprehensive Plan: Commercial Mixed Use
Title: Geotechnical Report Findings and Proposed Soluons
Introducon: The geotechnical report included in the package highlights certain soil condi@ons on the
site, specifically the presence of loose soils prone to liquefac@on. However, it is important to emphasize
that, when following the provided recommenda@ons, the site becomes suitable for the proposed
construc@on from a geotechnical standpoint.
Foundaon Support: The founda@ons for the proposed building can be securely supported by
conven@onal spread foo@ngs that rest on the na@ve soils. Addi@onally, these founda@ons will be further
improved and stabilized through the use of aggregate piers or Geopiers, as outlined in the report. This
approach will allow us to support the slab-on-grade floors.
Geopiers for Soil Stabilizaon: The installa@on of Geopiers serves as a crucial measure to stabilize the
soil effec@vely. These Geopiers will be employed according to the detailed recommenda@ons outlined in
the geotechnical report, ensuring their proper implementa@on during the construc@on phase.
Groundwater Management: During the site analysis, groundwater was encountered at a depth of 10
feet. To mi@gate the risk of water intrusion issues and avoid the need for temporary or permanent
dewatering discharge systems, we have decided not to provide underground parking. Instead, we have
made every effort to meet parking requirements above ground.
Risk Migaon: Upon comple@on of construc@on, and by adhering to the recommenda@ons specified in
the geotechnical report, we are confident that there will be minimal risk associated with the soil
condi@ons men@oned. Please refer to the a$ached le$er from the Geotechnical Engineer, which strongly
advises against below-grade parking.
Communicaon with Future Owners: We are commi$ed to transparency and will inform future owners
about the founda@on upgrades made to the site. This communica@on ensures that all stakeholders are
aware of the measures taken to ensure the safety and stability of the development.
In conclusion, we are fully dedicated to following the expert guidance provided in the geotechnical
report to ensure a secure and stable founda@on for our proposed construc@on. With these precau@ons
in place, we are confident in the safety and long-term viability of the new development.
(Aached also is a leer from the geotechnical engin eer confirming statements above)
Sincerely,
Veer Architecture, PLLC Lavina
Wadhwani, Principal
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone 425.415.0551 ♦ Fax 425.415.0311
www.riley‐group.com
TECHNICAL MEMORANDUM
Date: April 24, 2023
To: Andrew Van Gordon
City of Renton
From: Kristina Weller, PE
The Riley Group, Inc.
Subject: Dreamliner Project
511 Airport Way
Renton, Washington
RGI Project No: 2020‐618‐1
RGI previously prepared a geotechnical report for the proposed project. The soils encountered consisted
of interbedded layers of silt, sand, and silty sand. Groundwater was encountered at 10 feet below the
existing grade at the time of drilling. Based on the moisture content of the soils, the water levels may be
as shallow as 8 feet if wells were installed.
The soil conditions and water table represent a liquefaction hazard, therefore; we recommended
installing aggregate piers to mitigate the predicted settlements and allow suitable support for the
building.
We understand the City of Renton has requested the project explore the potential for underground
parking. Based on the water table on the site and the need for ground improvements for support of the
structure; the excavation below grade for a level of parking would require significant dewatering and
shoring, which may affect the adjacent structures, utilities, and streets. In addition, the foundation and
likely the slab would either need to be watertight construction or have an underslab drainage system.
Based on the plans, the temporary dewatering and underslab drainage system would have to be
pumped to the storm system and the system is unlikely to be sized for the additional flow. In many
jurisdictions, permanent groundwater discharge is not allowed to the storm system which would
necessitate watertight construction for a portion of the below grade level.
The additional costs associated with shoring, construction dewatering, permanent waterproofing, and
drainage for a below grade level would likely make the project infeasible from cost and construction
standpoint.