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HomeMy WebLinkAboutFPA 2022-00013 - FPA Reports - 10/18/2022 \4, ` MARTIG ENGINEERING 61 5 00718 2t72 2 P.O. Box 1693 � '9/der Allyn, WA 98524 (360) 275-4638 Cell (360) 507-0489 Email: MartigEngr(obatt net GEOTECHNICAL INVESTIGATION/ANALYSES REPORT August 17, 2022 (4-Pages of Text) & (13-Pages of Attachments) • Investigation Site: Three (3) Parcels, 6-7-Acre Composite Site (i) 22125-42-90063; -90062; -90061 (ii) Located Off Mason County Road: E North Island Drive, upon Hartstene Island • Owners: 1. Jim Charleston —22125-42-90063 Cell: 303 349-8727 2. John R. Hickman —22125-42-90062 Mason County; 22125-42-90063 • • Sec 25, T21 N, R2W WM • Geotechnical Report & Submittal Checklist Jim Charleston Email: JimCharieston@Windermere.com Martig Engineering has investigated the Geological Stability of the above referenced Properties, taking Site slope measurements and photographs to document Slope Stability Parameters, and reviewing all Published Topographic Maps and Soils Reports addressing the Site. The following Report summarizes our Findings, Conclusions and Recommendations. 1 A. Owners' Plan (at this time): The Owners' plan is to remove Dying/Danger trees from the composite 6.7 acres, and clean up previously fallen trees, all as proposed by Joe Staley of JDS Forest Management (see Attachment). B. Purpose of this Geotechnical Report: The purpose of this Report is to confirm that the proposed removal of Dying/Danger trees and the cleanup of previously fallen trees will not induce Geologic Instability of the subject 6.7-acre composite site. C. Findings of this Geotechnical Investigation/Analysis: 1. the subject composite site includes an unstable Marine Bluff Bank along its easterly boundary (the shoreline of Spencer Cove of Case Inlet); 2. No removal of standing Trees is proposed within the 50' Buffer(measured inland horizontally westward from the existing Top-of-Slope). Only existing downed trees, within the Buffer and along the Bluff Bank, are planned to be cleaned up, without removing any remaining intact root structures or damage to the existing Understory vegetation; 1 Dying/Danger and downed trees exist, within the composite area westerly of the 50' Buffer, and are planned to be removed by JDS Forest Management. An improved, graveled Driveway access exists for the proposed Tree removal operation; 4. The removal area is generally Flat, with undulating ground varying between elevations 105' & 100'. Therefore, no threat of overland flow erosion exists, and no erosion control measures are necessary. D. Conducted Investigations and Analyses• Martig Engineering confirmed that the 50' Buffer has been flagged to delineate the easterly edge of standing Danger-Tree removal, and confirmed the need to remove Danger Trees as proposed by JDS Forest Management. Measurements of the slope, where the subject Marine Bluff Slope is stabilizing, were taken, along with Photographs showing these slopes. The slope measurements confirmed the slopes upon the attached Site Elevation View (Section A-A). Photos of these slopes are shown below. The description of the Site Soils is presented within the attached JDS Forest Management attachment_ Y E. Report Findings: 1. This Property has been determined to be GEOLOGICALLY STABLE, and safe to allow the proposed tree removal; 2. This stability is primarily due to the presence of undisturbed, underlying dense, consolidated Till; 3. The remote Site is safely accessed at the end of an existing graveled Driveway, connected to the east side of E North Island Drive; 4. No tributary surface bodies of water exist upgradient, and given the fact that the Tributary Area for Surface Water Runoff is very small, no such offsite impact is presented; 5. Given the age of the existing, large Canopy trees and Stumps, we know that the property has historically, experienced several significantly large Earthquakes. However, the underlying dense consolidated soils have proven strong enough to resist these induced earthquake forces; 6. Healthy Canopy and Understory vegetation cover the Property and no new Access Roadway construction is necessary. This concludes our Geotechnical Report for the above referenced Site, reporting that subject Property is Geologically Stable and that the proposed Cutting of the Site's Danger Trees will not adversely impact this stability. I, Kenneth W. Martig, Jr., PE, of Martig Engineering, have completed this required Geo- Technical Report, as documented within this letter Report and its attachments. I am familiar with this site, having lived in the area for decades and having visited and inspected the site and its surrounds. As documented, the proposed activity does not trigger any potential landslide hazards and no significant environmental impacts will result if this proposal is permitted as discussed herein. 3 Certified by: L � en Ma i , r. S PE Martig Engineeri o bNAL �a ATTACHMENTS: 1. PLAN VIEW(with 5-Contours): 1" = 100' 2. ELEVATION VIEW OF EXISTING SITE; Section A—A; 1" = 100' Horiz_ & V = 100' Vert.; 3. GOOGLE EARTH Aerial Photo 2022- 4. JDS Forest Management Documents 5. Drainage Minimum Requirement#2: 6. 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