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CANODCity of Edmonds Critical Area Notice of Decision Applicant: J r rl S Property Owner: Critical Area File #: OO / Permit Number: 2D i q © 6 3 Site Location: Z(c( S l� Parcel Number: Oo q 73.w000 S-Z� Project Description: 41V ❑ 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. Critical 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 and 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. ❑ Unfavorable Critical Area Decision. The proposed project is not exempt or does 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 regulations. See attached findings of noncompliance. f Favorable 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 of Edmonds critical area regulations. 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). If&D �a Notice on Title. -Critical area notice on title recorded under AFN A, 11�_ (0 1-l.�l�J/�n ( -2- 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, if any, for the permit or approval involved. Revised 1112912016 COBALT GEOSCIENCES March 2, 2020 Corry Morris corUmorris(L)gmail.com RE: Geotechnical Evaluation Existing Construction 219 Skyline Drive Edmonds, Washington ttvl a �c Cobalt Geosciences, LLC P.O. Box 82243 Kenmore, Washington 98028 MAR 0 2 2020 BUILDING DEPARTMENT CITY OF EDMONDS We have prepared this letter to discuss aspects of the recently constructed project at the referenced site with regard to relevant sections of the Edmonds City Code and Community Development Code. Specifically, Comment No. 1 from a City of Edmonds letter dated June 1o, 2o19 discusses the location of a hot tub within 50 feet of a mapped steep slope area. Site and Project Description The site is located at 219 Skyline Drive in Edmonds, Washington. The property consists of one irregularly shaped parcel (No. 00423000005200) with a total area of about 0.27 acres. The east -central portion of the property is developed with a multi -story single-family residence with attached garage and driveway. The remainder of the property is undeveloped and vegetated with grasses, bushes/shrubs, and sparse trees. There is a hot tub on a concrete slab located in the western portion of the property. The property slopes downward from east to west at magnitudes ranging from about 5 to 45 percent and total relief of about 30 feet. There are localized areas with magnitudes of 30 to 45 percent west of the residence extending further west. These slopes are up to 10 feet in height and developed with graded benches, landscaped areas with boulders, and other landscaping features. There are 2 to 8 feet tall rockery walls along the south and west property lines, facing apparent cut native soils. The hot tub and slab are located in a landscaped area just above a moderately steep slope and short rockery wall. Area Geology The site is underlain by Vashon Glacial Till. Vashon Glacial Till consists of a heterogeneous mixture of silt, sand, clay, and gravel. These deposits are typically dense to very dense below a thin weathered zone. Glacial till is typically impermeable and resistant to global instability. Geologic Hazards We understand that the site contains areas considered to be steep slope hazards by the City of Edmonds municipal code. The slope areas west of the residence have local relief of about 10 feet and have slope magnitudes of up to 45 percent. These areas are fully vegetated with herbs, bushes, and trees; and locally have rockery walls facing previous cuts. www.cobaltgeo.com (2o6) 331-1097 March 2, 2020 Page 2 of 5 Geotechnical Evaluation Code Items and Discussion 23.80.o6o Development standards — General requirements. A. Alterations of geologically hazardous areas or associated buffers may only occur for activities that: i. Will not increase the threat of the geological hazard to adjacent properties beyond predevelopment conditions; 2. Will not adversely impact other critical areas; 3. Are designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than predevelopment conditions; and 4. Are certified as safe as designed and under anticipated conditions by a qualified engineer or geologist, licensed in the state of Washington. 41! t•. t 1 • • r 7—MMOoMmUll1• , ' _ .� 1 1 ,1 • 1 •r 1• •. <1• no R. I MIX-11901, 1 • • • • ' 1 1 • • 4 1 1 • • • r 1 ' , • .� • 1 t • • • ' IT; ,. • • 1 • • t 23.80.07o Development standards — Specific hazards. A. Erosion and Landslide Hazard Areas. Activities on sites containing erosion or landslide hazards shall meet the requirements of ECDC 23,.80.o6o, Development standards — General requirements, and the specific following requirements: 1. Minimum Building Setback. The minimum setback shall be the distance required to ensure the proposed structure will not be at risk from landslides for the life of the structure, considered to be 120 years, and will not cause an increased risk of landslides taking place on or off the site. A setback shall be established from all edges of landslide hazard areas. The size of the setback shall be determined by the director consistent with recommendations provided in the geotechnical report to eliminate or minimize the risk of property damage, death, or injury resulting from landslides caused in whole or part by the development, based upon review of and concurrence with a critical areas report prepared by a qualified professional; a wioderately teer) slope extendine downward to the west, The existing lQcAtion is 511it &L—and I •!• •1 � Me 2. Buffer Requirements. A buffer may be established with specific requirements and limitations, including but not limited to, drainage, grading, irrigation, and vegetation. Buffer requirements shall be determined by the director consistent with recommendations provided in the geotechnical report to eliminate or minimize the risk of property damage, death, or injury resulting from landslides caused in whole or part by activities within the buffer area, based upon review of and concurrence with a critical areas report prepared by a qualified professional; (2o6) 331-1097 March 2, 2020 Page 3 of 5 Geotechnical Evaluation The site currently fully developed. No specific buffer (in addition to what is present currently required from a geotechnical standpoint. We recommend that all sloped areas remain vegetated and protected from erosion through continued maintenance of existing surface landscaping materials/vegetation. 3. Alterations. Alterations of an erosion or landslide hazard area, minimum building setback and/or buffer may only occur for activities for which a hazards analysis is submitted and certifies that: a. The alteration will not increase surface water discharge or sedimentation to adjacent properties beyond predevelopment conditions; b. The alteration will not decrease slope stability on adjacent properties; and c. Such alterations will not adversely impact other critical areas; 4. Design Standards within Erosion and Landslide Hazard Areas. Development within an erosion or landslide hazard area and/or buffer shall be designed to meet the following basic requirements unless it can be demonstrated that an alternative design that deviates from one or more of these standards provides greater long-term slope stability while meeting all other provisions of this title. The requirement for long-term slope stability shall exclude designs that require regular and periodic maintenance to maintain their level of function. The basic development design standards are: a. The proposed development shall not decrease the factor of safety for landslide occurrences below the limits of 1.5 for static conditions and 1.2 for dynamic conditions. If stability at the proposed development site is below these limits, the proposed development shall provide practicable approaches to reduce risk to human safety and improve the factor of safety for landsliding. In no case shall the existing factor of safety be reduced for the subject property or adjacent properties; b. Structures and improvements shall be clustered to avoid geologically hazardous areas and other critical areas; c. Structures and improvements shall minimize alterations to the natural contour of the slope, and foundations shall be tiered where possible to conform to existing topography; d. Structures and improvements shall be located to preserve the most critical portion of the site and its natural landforms and vegetation; e. The proposed development shall not result in greater risk or a need for increased buffers on neighboring properties; f. The -use -of retaining walls -that -allow the -maintenance -of -existing -natural -slope -area -is -preferred over graded artificial slopes; and www.cobaltgeo.com (2o6) 331-1097 March 2, 2020 Page q of 5 Geotechnical Evaluation g. Development shall be designed to minimize impervious lot coverage; slab/hotfactor of safety for landslide activity do not appear to have been or will not be ffected by the existing • development, 5. Vegetation Retention. Unless otherwise provided or as part of an approved alteration, removal of vegetation from an erosion or landslide hazard area or related buffer shall be prohibited; 6. Seasonal Restriction. Clearing shall be allowed only from May ist to October ist of each year; provided, that the director may extend or shorten the dry season on a case -by -case basis depending on actual weather conditions, except that timber harvest, not including brush clearing or stump removal, may be allowed pursuant to an approved forest practice permit issued by the city of Edmonds or the Washington State Department of Natural Resources; 7. Point Discharges. Point discharges from surface water facilities and roof drains onto or upstream from an erosion or landslide hazard area shall be prohibited except as follows: a. Conveyed via continuous storm pipe downslope to a point where there are no erosion hazard areas downstream from the discharge; b. Discharged at flow durations matching predeveloped conditions, with adequate energy dissipation, into existing channels that previously conveyed storm water runoff in the predeveloped state; or c. Dispersed discharge upslope of the steep slope onto a low -gradient, undisturbed buffer demonstrated to be adequate to infiltrate all surface and storm water runoff, and where it can be demonstrated that such discharge will not increase the saturation of the slope; and We enncnr with the ahnve code items and have no additional comments at this time. Conclusions & Recommendations It is our opinion that the hot tub and supporting slab are located within a zone of stable soils with no additional setback or buffer from slope or erosion hazard areas. The construction will not and does not adversely affect slope stability or geologic hazards within 200 feet of the property. Closure The information presented herein is based upon professional interpretation utilizing standard practices and a degree of conservatism deemed proper for this project. We emphasize that this report is valid for this project as outlined above and for the current site conditions and should not be used for any other site. This letter does not discuss the potential or likelihood for soil settlement below the slab, if fill is present. Soil settlement due to poor compaction or loose soil removal is not part of our analysis and would be the responsibility of the builder/contractor and/or owner. (2o6) 331-1097 March 2, 2020 Page 5 of 5 Geotechnical Evaluation Sincerely, Cobalt Geosciences, LLC WA C6 548 6 0 �� --is T E��- ON Exp. 6/26/2020 Phil Haberman, PE, LG, LEG Principal PH/sc 2513 4... 1 nlip A. Haberm?.n www.cobaltgeo.com (2o6) 331-1097 kgbL-&, . N A Cobalt Geosciences, LLC Hot Tub and Slab SITE PLAN Ken Box ,82243 WA COBALT21 Skyline Drive Kenmore, WA 98028 9 Y (2o6) 331-1097 GEOSCIENCES Edmonds, Washington FIGURE i unvw.cobaltgeo.com cobalt Qeq@gnmil coin Emm -✓1� Cam°"'' ��� � J� � L L 0$iAln1 SIOE_S%tx,Z j�F12.h�liT �I •� - -- - - PROPER � wn�riiRlK�iiY17E1 , -- ----------�1 AMAGEGRAM H8OHr 4,004, � L— / o E ` \ ZA 4f ALL WORK SUBJECT TO '`iMP CTION FOR CODE COMPLIANCE,, 2d I I I I Low ununrnAw%mr ri I Z 01D[.WALI< I I II co � I 1 I � /-T-T I It urew women I I I � I I VED BY ENGINEERMIG -:_7 � � t j 1,1 mo Morris Originals, Bellingham, WA Corry Mords, Prinbipal c. 300.223.3359 Z_ vr. nx+rrL.orlpinalo.com f J Corner�Flqg iCICS �P;jUIYGCI � Mt CEIVED es �10 ir er 30 D BY NNI Z z W 0 w a CITY OF ELRICNDS BUILDING DE R MENT WORK ADDRESS' OWNER N APPROVED DATE: BLDG. OFFICIAL: P E Ri AAI -r NUM BER .r L ) 201 "r OCR