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CANOD.pdfCity of Edmonds Critical Area Notice of Decision Applicant: Property Owner: 1-49 Critical Area File #:Permit Number- ZO 1 00 I g�O OO Site Location: Parcel Number: 0000 ?too .005 Project Description: vo ❑ Conditional Waiver. No critical area report is required for the project described above. 1. There will be no alteration of a Critical Area or its required buffer. 2. The proposal is an allowed activity pursuant to ECDC 23.40.220, 23.50.020, and/or 23.80.040. 3. The proposal is exempt pursuant to ECDC 23.40.230. Erosion Hazard. Project is within erosion hazard area. Applicant must prepare an erosion and sediment control plan in compliance with ECDC 18.30. JZf-Critica�l Area Report Required. The proposed project, is within a critical area and/or a critical area buffer and a critical area report is required. A critical area report has been submitted aced evaluated for compliance with the following criteria pursuant to ECDC 23.40.160: 1. / The proposal minimizes the impact on critical areas in accordance with ECDC 23.40.120, Mitigation sequencing; 2. The proposal does not pose an unreasonable threat to the public health, safety, or welfare on or off the development proposal site; 3. The proposal is consistent with the general purposes of this title and the public interest; 4. Any alterations permitted to the critical area are mitigated in accordance with ECDC 23.40.110, Mitigation requirements. 5. The proposal protects the critical area functions and values consistent with the best available science and results in no net loss of critical functions and values; and 6. ! The proposal is consistent with other applicable regulations and standards. Z Unfavorable Critical Area Decision. The proposed project i's not exempt or docs not, adequately mitigate its impacts on critical areas and/or does not comply with the criteria in ECDC 23,40.160 and the provisions of the City of Edmonds critical'area regttlautions. See attachedfindings of noruco noliane a �6y' avorable Critical Area Decision. The proposed project as described above and as shown on; the attached site plan meets or is exempt from the criteria in ECDC 23.40.160 Review Criteria, and complies with the applicable provisions of the City ofEdmonds dmonds critical area regu Iations. Any subsequent changes to the proposal shall void this decision pending re -review of the proposal. ❑ Conditions. Critical Area specific condition(s) have been applied to the permit number referenced above. See referenced permit number for specific condition(s). Notice on Title. Critical area notice on title recorded _under AFN ?� t -7O 3 / 0w t6f 10,CbSs Reviewer Signature Date Appeals: Any decision to approve, condition, or deny a development proposal or other activity based on, the requirements of critical area regulations may be appealed according to, and as part of, the appeal procedure, °i.f any, for the permit or approval involved. Revised 11129/2016 � ua N i Gary A. Flowers, PLLC tttS t i��^t° Geological & Geotechnical Consulting 19532 12th Avenue NE Shoreline, WA 98155-1106 February 13, 2017 Project No. 14-045 Mr. Henry Byam c/o Wesco Equipment Division 21601 66th Avenue West Mountlake Terrace, WA 98023 Subject: Critical Areas/Geotechnical Report Proposed New Lloyd White Residence 8545 Talbot Road Edmonds, Washington Dear Mr. Byam: CITY COPY As per the January 17, 2017 letter regarding Plan Review Comments for Plan Check #2017-0029, Swimming Pool at 8545 Talbot Road, from Mike Clugston, AICP, Associate Planner at the City of Edmonds, an updated geotechnical report is required for the new swimming pool due to code changes that were adopted in May 2016. We previously provided a Geotechnical Report for the planned home and swimming pool development on November 16, 2014 and revised the report to meet Critical Areas code requirements at that time on July 30, 2015. As stated in our previous report, as per ECDC 23.80.020.A.1, A.2 and A.3 (changed via the current code to ECDC 23.80.020.A.1, A.2, A.3 and A.4) the site does not meet the requirements for an erosion hazard, as per ECDC 23.80.020.B.2 (changed via the current code to ECDC 23.80.020.B.4 and .8) the site does meet the definition of a landslide hazard and as per ECDC 23.80.020.0 the site does not meet the definition of a seismic hazard. In accordance with ECDC 23.40.090.D.3 this report is prepared by Gary A. Flowers, P.E.G and Robert M. Pride, P.E., G.E. Mr. Flowers is a professional geologist and engineering geologist in the state of Washington and a licensed geologist in the state of North Carolina. He resides at 19532 12th Avenue NE, Shoreline, WA 98155 and was educated at the University of Washington. Mr. Pride is a professional engineer, geotechnical engineer and geological engineer, licensed in Alaska, Washington, Oregon, Arizona and California. Mr. Pride was educated at the University of California, Berkeley and resides at 13203 Holmes Point Drive, NE, Kirkland, WA 98034. Together Mr. Flowers and Mr. Pride have more than 90 years of consulting experience in many areas of the world but mostly within the greater Puget Sound region. They have provided consultation on many steep slope projects throughout the region. Gary A. Flowers, PLLC. 19532 12'^ Avenue NE Shoreline, Washington 98155-1106 206-819-4304 Lloyd White Residence 2017 Revised Critical Areas/Geotechnical Report 8545 Talbot Road, Edmonds, Washington Conclusions, Opinions and Recommendations All recommendations regarding proximity to nearby landslides (nothing within 200 feet), slope stability, soil bearing, landslide hazard mitigation requirements, buffers and setbacks that were presented in our previous report dated July 30, 2015 remain applicable. The planned new swimming pool construction will not disturb the steep slope area along the west side of the property, will not decrease the subject slope stability below 1.5 for static and 1.2 for seismic loading conditions, will not increase the threat of the geological hazard to adjacent properties beyond predevelopment conditions, will not adversely impact other critical areas, is designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than predevelopment conditions and is safe as designed under anticipated conditions. Published geologic maps of the area indicated that the site is underlain by Vashon age glacial till sediments. During construction of the residence, which included an excavation on the order of 20 feet deep, very dense, silty sand with gravel (glacial drift/glacial till) sediments were exposed which confirmed our previous findings on the site. In addition, the Coastal Zone Atlas shows the site as Stable with a Modified slope (due to past railroad construction). The planned swimming pool will be located 40 feet from the top of the steep slope and the pool concrete patio will extend to within about 34 feet from the top of the steep slope. In accordance with ECDC 23.80.070.A.1 a minimum setback shall be established to ensure the proposed structure will not be at risk from landslides for the life of the structure, considered to be 120 years. This report is for an in the ground swimming pool instead of a house and the code does not define the lifespan for a pool which we would anticipate to be less than for the house. ECDC 23.80.70.A.2 also allows for establishment of a buffer, if needed. Given the overall slope height of 30 to 32 feet the planned concrete patio and the pool structure will be beyond a 1 H:1 V line from the toe of the slope to the top of the ground surface such that there will be no additional load bearing onto any part of the steep slope. The subsurface soils consist of very dense, glacially consolidated silty sand with gravel (glacial till) that will stand vertical for decades in the absence of ground water. At its current 55 to 60 -degree inclination, and with the absence of ground water, the slope is considered stable with a factor of safety well in excess of 2.0. As per ECDC 23.80.070.A.3, it is our opinion that the pool and patio construction will not increase surface water discharge or sedimentation to adjacent properties beyond predevelopment conditions and will not decrease slope stability on adjacent properties, will not adversely impact other critical areas. It is our opinion that the planned pool location and distance from the steep slope area will provide the required lifespan for the structure and a setback or buffer beyond the planned 34 feet should not be required. In addition, our previous report recommended a pool leak containment system typically consisting of a heavy duty liner, sump and positive or passive drainage from the sump. Current plans call for an approximate 8 -inch layer of clean drain rock in the bottom of the pool excavation with a drain pipe that connects to the approved storm water drainage system for the site. Based on the very Gary A. Flowers, PLLC. 19532 12' Avenue NE Shoreline, Washington 98155-1106 206-819-4304 2 Lloyd White Residence 2017 Revised Critical Areas/Geotechnical Report 8545 Talbot Road, Edmonds, Washington dense and high impermeable sediments observed in the house excavation it is our opinion that this methodology will provide suitable drainage from the bottom of the excavation should a leak ever develop. We do recommend that the pool excavation have a slight slope prior to placement of the drain rock in order to provide positive drainage to the drain pipe. The soils that will be exposed on the site have a moderate erosion potential under a concentrated flow regime. Once disturbed the erosion potential will be high. However, due to the flatlying nature of the site, and the lack of any construction/soil disturbance on the steep slope, Standard City of Edmonds erosion control measures should be sufficient for this site. Special care must be taken to keep any sediment laden water from discharging into the nearby Puget Sound. Absolutely no excavated soils should be placed on the steep slope area or within 10 feet of the top of slope. SUMMARY Based on our site reconnaissance, observation of the exposed soils in the deep house excavation, and literature research, the site is suitable for the proposed swimming pool development provided the recommendations provided herein are properly implemented. It is our opinion that the planned construction meets all the geological and geotechnical requirements of the Edmonds Municipal Code as detailed within the report. Our findings and recommendations provided in this report were prepared in accordance with generally accepted principles of engineering geology and geotechnical engineering as practiced in the Puget Sound area at the time this report was submitted. We make no other warranty, either express or implied. Sincerely, Gary Ai. Flowers " i it lgdl� Gary A. Flowers, P.G., P.E.G. Robert M. Pride, P.E. Engineering Geologist Geotechnical Engineer Attachments: Site Plan Gary A. Flowers, PLLC. 19532 12' Avenue NE Shoreline, Washington 98155-1106 206-819-4304 ,Vj 021 el9 vK 01-v 00— rr r Ll_ ° NWnri, a , C.�"' „„Gr^ °, 19 rAIL,....� � ( 8 Y 0ul w� a VVI � 1 ° � I �.5 . ...... ._ ... _... [ ti x �w �• f, `n CIO 3 ' 41s a- v wwv"� J rw 11 #N�,„„ J � p I�"$f ,r pp e P r �q 'Ir v,. T,.,.."v Q� ..... .. ._ —— I �� t $ i—��� Ym9�••9 � .Y --w � N�-�a .y.,a..� �. a,,x��m.�.. r n r y e o. � a u �. R � � � � A_� , " . . , .