HomeMy WebLinkAboutEx14_Supplemental_Letter_from_The_Riley_Group
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone 425.415.0551 ♦ Fax 425.415.0311
www.riley-group.com
April 23, 2020
Ms. Valery Kalashnikov
Nord West Properties, LLC
13220 42nd Avenue East
Tacoma, Washington 98446
RE: Response to Comments
Aberdeen Townhomes
957 Aberdeen Avenue Northwest
Renton, Washington
RGI Project No. 2018-223
References: Encompass Engineering and Surveying, Preliminary Grading and Drainage Plan
dated April 16, 2020
The Riley Group, Inc. Geotechnical Engineering Report dated November 27, 2018
Dear Ms. Kalashnikov:
As requested, The Riley Group, Inc. (RGI) is providing this letter to respond to the City of Renton
Comments dated January 10, 2020
Comment 1 f. Per RMC 4-3-050 (G)(2) steep slope and landslide hazard buffers shall be
established by the geotechnical engineer. Section 4.6.6 of the Geotechnical Report states: “The
proposed townhomes have been designed to step down with the existing topography and the
majority of the development is on the least sensitive area of the site. Three townhomes are
proposed on top of the slope outside of the sensitive slopes and setback from the slope. Based
on the results of our subsurface explorations and slope stability analysis, the proposal will not
increase the threat of the geological hazard to adjacent or abutting properties beyond
predevelopment conditions; and will not adversely impact other critical areas; and the proposed
development can be safely accommodated on the site”, however, the report references a
previous site plan which shows the proposed buildings set back considerably further than the
current site plan and does not take into account the drainage structures and retaining wall which
is located on and around the steep slope. Prior to land-use approval, the geotechnical engineer
shall provide a quantitative analysis of the steep slope and landslide hazard area and provide set-
back based on the recommendations for the updated site plan and facilities being proposed closer
than identified in the report. Additionally, a 15’ building set-back line (BSBL) will be required from
the edge of the buffer, including the case that the buffer is determined to be 0’. Building, retaining
walls and subsurface drainage structures shall not be located within the buffer or BSBL. Update
the preliminary plans, geotechnical report and TIR to include any changes resulting in the buffer
and BSBL and relocating facilities and/or buildings outside of this area.
RGI Response: RGI completed a stability analysis for the currently proposed conditions as shown
on the referenced plans and included the proposed drainage facilities. Per our recommendation,
the retaining wall that was previously shown on the top of the slope has been removed and the
grade changes will be accomplished with grading and the wall is not necessary except for the
southwest corner and the wall is at the setback line.
EXHIBIT 14
DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
BB'AA'CC'04/2020Corporate Office17522 Bothell Way NortheastBothell, Washington 98011Phone: 425.415.0551Fax: 425.415.0311Aberdeen TownhomesRGI Project Number2018-223Date Drawn:Address: 957 Aberdeen Avenue Northeast, Renton, Washington 98056Slope Stability Cross SectionsFigure 1Approximate Scale: 1"=60'03060120N= Slope stability cross section= Site boundaryDocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
1.6001.60011 150.00 lbs/ft21.6001.600Material NameColorUnit WeightlStrength TypeCoheionlPhiWater SurfaceRuSilty sand125Mohr-Coulomb20036Piezometric Line 1Silt110Mohr-Coulomb40034None0Fill125Mohr-Coulomb036None0Safety Factor0.0000.2500.5000.7501.0001.2501.5001.7502.0002.2502.5002.7503.0003.2503.5003.7504.0004.2504.5004.7505.0005.2505.5005.7506.000+275250225200175150125-50-250255075100125150175200Analysis DescriptionProposed Static A-A'CompanyRiley Group, Inc.Scale1:311Drawn ByELWFile NameProposed Static.slimDate11/20/2018, 10:14:49 AMProjectAberdeen TownhomesSLIDEINTERPRET 6.009DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
1.6641.6641 150.00 lbs/ft21.6641.664Material NameColorUnit WeightlStrength TypeCoheionlPhiWater SurfaceRuSilty sand125Mohr-Coulomb20036Piezometric Line 1Silt110Mohr-Coulomb40034None0Fill125Mohr-Coulomb036None0Safety Factor0.0000.2500.5000.7501.0001.2501.5001.7502.0002.2502.5002.7503.0003.2503.5003.7504.0004.2504.5004.7505.0005.2505.5005.7506.000+275250225200175150-60-40-20020406080100120140160180Analysis DescriptionProposed Static - B-B'CompanyRiley Group, Inc.Scale1:290Drawn ByELWFile NameProposed Static B-B'.slimDate11/20/2018, 10:14:49 AMProjectAberdeen TownhomesSLIDEINTERPRET 6.009DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
2.0402.0401 150.00 lbs/ft22.0402.040Material NameColorUnit WeightlStrength TypeCoheionlPhiWaterSurfaceRuSilty sand125Mohr-Coulomb20036PiezometricLine 1Silt110Mohr-Coulomb40034None0Safety Factor0.0000.2500.5000.7501.0001.2501.5001.7502.0002.2502.5002.7503.0003.2503.5003.7504.0004.2504.5004.7505.0005.2505.5005.7506.000+300250200150-75-50-250255075100125150175200225Analysis DescriptionProposed Static - C-C'CompanyRiley Group, Inc.Scale1:374Drawn ByELWFile NameProposed Static C-C'.slimDate11/20/2018, 10:14:49 AMProjectAberdeen TownhomesSLIDEINTERPRET 6.009DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
1.1171.11711 150.00 lbs/ft21.1171.117Material NameColorUnit WeightlStrength TypeCoheionlPhiWater SurfaceRuSilty sand125Mohr-Coulomb20036Piezometric Line 1Silt110Mohr-Coulomb40034None0 0.2Safety Factor0.0000.2500.5000.7501.0001.2501.5001.7502.0002.2502.5002.7503.0003.2503.5003.7504.0004.2504.5004.7505.0005.2505.5005.7506.000+275250225200175150125-50-250255075100125150175200Analysis DescriptionProposed Seismic A-A'CompanyRiley Group, Inc.Scale1:310Drawn ByELWFile NameProposed Seismic A-A'.slimDate11/20/2018, 10:14:49 AMProjectAberdeen TownhomesSLIDEINTERPRET 6.009DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
1.1731.1731 150.00 lbs/ft21.1731.173Material NameColorUnit WeightlStrength TypeCoheionlPhiWater SurfaceRuSilty sand125Mohr-Coulomb20036Piezometric Line 1Silt110Mohr-Coulomb40034None0Fill125Mohr-Coulomb036None0 0.2Safety Factor0.0000.2500.5000.7501.0001.2501.5001.7502.0002.2502.5002.7503.0003.2503.5003.7504.0004.2504.5004.7505.0005.2505.5005.7506.000+260240220200180160140-40-20020406080100120140160180Analysis DescriptionProposed Seismic - B-B'CompanyRiley Group, Inc.Scale1:281Drawn ByELWFile NameProposed Seismic B-B'.slimDate11/20/2018, 10:14:49 AMProjectAberdeen TownhomesSLIDEINTERPRET 6.009DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2
1.3681.3681 150.00 lbs/ft21.3681.368Material NameColorUnit WeightlStrength TypeCoheionlPhiWater SurfaceRuSilty sand125Mohr-Coulomb20036Piezometric Line 1Silt110Mohr-Coulomb40034None0 0.2Safety Factor0.0000.2500.5000.7501.0001.2501.5001.7502.0002.2502.5002.7503.0003.2503.5003.7504.0004.2504.5004.7505.0005.2505.5005.7506.000+300250200150-50-250255075100125150175200225Analysis DescriptionProposed Seismic - C-C'CompanyRiley Group, Inc.Scale1:374Drawn ByELWFile NameProposed Seismic C-C'.slimDate11/20/2018, 10:14:49 AMProjectAberdeen TownhomesSLIDEINTERPRET 6.009DocuSign Envelope ID: 69D0A746-C343-49C8-931A-17990D5283F2