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Hilliard Pond Waiver.pdfIP C. 1 S°Iv CITY OF EDMONDS 121 5TH AVENUE NORTH • E©MONDS, WA 98020 • (425) 771-0220 • FAX (425) 771-0221 Website: www.ci.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering July 9, 2009 Ron & Susan Hilliard 20831 23`d Ave W Lynnwood, WA 98035 RE: Request for waiver per ECDC 19.10.070 for a small pond 15515 75111 Place West, Edmonds Dear Mr. & Mrs. Hilliard, GARY HAAKENSON MAYOR The City is in receipt of your request for waiver to allow installation of a small pond as a landscaping feature at your property currently under construction at 15515 75d, Place W. The site is located in the Earth Subsidence Landslide Hazard Area which is regulated under ECDC Chapter 19.10. Ponds are specifically prohibited in the Earth Subsidence Landslide Hazard Area as set forth in ECDC 19:10.070D unless a waiver is first obtained per ECDC 19.10.070E. Your request for waiver was sent for peer review by our geotechnical consultant, Landau Associates, as permitted in ECDC 19.10.070.E. It is their opinion that the water feature, as it was described in the request to have been constructed, should not have an adverse affect on slope stability as tong as it is constructed and maintained properly. A copy of their Technical Memorandum dated .lune 29, 2009 is attached for your information. Based on the information from your geotechnical engineer and opinion from the City's geotechnicat consultant that the subject pond is not likely to trigger or otherwise contribute to any landslide hazard or earth subsidence risk if constructed and .maintained properly, it is my determination that the request for waiver for the proposed pond is approved. Please recognize that the presence of this feature and any defects in its design or construction, -or improper maintenance and operation, could expose you as owners to damages or liabilities associated with slope movement that is exacerbated by the failure of this water feature to perform as intended. Ann Bullis, CBO Building Official • Incorporated August 11, 1890 • Sister Citu - Hekinan_ Janan LANDAU 14 ASSOCIATES TECHNICAL MEMORANDUM R&ROM6MOL,GBXKHM=I TO: Ann Bullis, Building Official City of Edmonds Development Services Department, Building Division " FROM: Dennis R. Stettler, P.E. DATE: June 29, 2009 RE: SUPPLEMENTAL GEOTECHNICAL PEER REVIEW RELATED TO WATER FEATURE BUILDING PERMIT No. 2008-0117 HILLIARD SFR -15515 75TH PLACE WEST EDMONDS, WASHINGTON This technical memorandum provides our geotechnical peer review comments related to a water feature constructed at the Hilliard residence within the Earth Subsidence and Landslide Hazard Area (ESLHA) of North Edmonds. Landau Associates has previously conducted a geotechnical peer review for the project and several supplemental issues, and the results of those previous reviews have been documented in technical memoranda provided to the City of Edmonds (City)- The City has issued a building permit and the construction of the residence is largely complete at this time. The current review addresses a water feature that has been constructed on the property that was not a part of the original building permit application package reviewed by the City and Landau Associates. Our services for this task are covered by Task Order No. 09-10 of the On -Call and Emergency/Disaster Response Geotechnical and Environmental Engineering Services Contract between Landau Associates and the City. The project has been constructed within the Earth Subsidence and Landslide Hazard Area of North Edmonds and is required to meet the requirements of Edmonds Community Development Code (ECDC) 19.10 that is applicable to this area. ECDC Section 19.10.070D prohibits the construction of "ponds or other artificial impoundments of water" within the earth subsidence and landslide hazard area because of the critical relationship of groundwater to overall stability of the area and concerns that surface water infiltration or discharge to the ground could adversely impact groundwater levels and slope stability. The water feature that has been constructed on the property is not consistent with the requirements of ECDC Section 19.10.070D. ECDC Section 19.10.070E states that "The prohibitions established in subsection (D) of this section shall apply unless the property owner requests a waiver based upon the written analysis of a geotechnical engineer which clearly establishes that the proposed improvement will have no reasonable likelihood of triggering or otherwise contributing to any landslide hazard or earth subsidence risk either on the site or in the neighboring earth subsidence or landslide hazard area." 130 2nd Avenue South • Edmonds, WA 98020 • (425) 778-0907 9 fax (425) 778-6409 • www.landauinc.com Cornerstone Geotechnical, Inc. (the geotechnical engineer of record for the project) has prepared a letter addressing this issue titled: Water Feature Letter, Proposed Ron Hilliard Residence, 15515 75th Place West, Edmonds, WA, CG File No. 2212, Building Permit #2008-0117. Prepared for Mr. Ron Hilliard by Cornerstone Geotechnical, dated June 19, 2009. Cornerstone Geotechnical did not directly observed the installation of the water feature, but has relied on information provided by Steve Barnes, the project architect, regarding the design and construction of the water feature. Cornerstone Geotechnical states that they were informed that the water feature was constructed with a plastic liner at the base to prevent water from seeping into the onsite soils, and a felt base was placed beneath the plastic liner to provide a cushion. Cornerstone Geotechnical provides their opinion that "the water feature will not adversely affect the stability of the sloping conditions on the site." A water feature that contains a properly designed, constructed, and maintained impermeable liner that prevents any infiltration or discharge of surface water to the ground or groundwater should not have an adverse affect on slope stability. On that basis, the waiver request to allow the water feature to remain appears to be reasonable. The property owner should recognize that the presence of this feature and any defects in its design or construction, or improper maintenance and operation, could expose the owner to damage or liabilities associated with slope movement that is exacerbated by the failure of this water feature to perform as intended. This technical memorandum has been prepared for use by the City in evaluating the requested waiver for the water feature constructed at the Hilliard single family residence at 15515 75ffi Place West. The focus of this review was the geotechnical aspects of the request. The purpose of the review was to assess the adequacy of the waiver request for compliance.with City requirements contained in ECDC 19.10 and conformance with conventionally accepted geotechnical engineering practices. This geotechnical peer review by Landau Associates does not lessen the requirements for the applicant's geotechnical consultant, and other design professionals, to prepare an appropriate design for the site conditions. We appreciate this opportunity to be of service to the City. Please contact us if you have any questions or if we maybe of further service_ DRSlrgm 6129109 \Tdmdatalorejects%07411445Fileflm\n%WaterFeatureGeotPearReview_tm.doc LANDAU ASSOCIATES 2 2083123rd Ave w Lynnwood, WA 98036 Phone (425) 771.0696 Ronh@pacgeoinc.com July 7, 2009 City of Edmonds Patrick Lawler Planning Department Edmonds, Washington Re: Hilliard Residence BLD20090248 - Water Feature Waiver Request Dear Patrick, The purpose of this letter is to request a waiver to allow a water feature to exist at our new home site within the Meadowdale Beach Slide Area. Apparently there has been a lot of discussions concerning this between my architect, Steve Barnes, and City of Edmonds staff. The water feature consists of a small waterfall that flows into a small pond. The water is then recirculated back to the top of the waterfall. The entire feature is lined with an impermeable, heavy duty, rubberized, pond liner. The pond area is approximately 15' long by 3' wide and 9" deep with a trough at the end for a pump. The pond holds roughly 350 gallons. The feature is not plumbed and must be manually filled. I am attaching a letterfrom my geotechnical engineer stating the water feature should have no adverse affect on the slope. I am also including a photo of the feature and some correspondence between the architect and the City. 1 appreciate your consideration in granting usthis waiver allowing the water feature. Sincerely, ,,7 x �; d n '' G9 JR I' -` 1 tI�� Cornerstone OW Geotechnical, Inc. Consulting Geotechnical Engineers & Geologists June 19, 2009 Mr. Ron Hilliard 6608 — 216' Street SW, Suite 304 Mountlake Terrace, WA 98043 Water Feature Letter Ron Hilliard Residence 15515 — 75h Place West Edmonds, Washington CG File No. 2212 Building Permit # 2008-0117 Dear Mr. Hilliard: u JUL7CJ 8 `L u!'11351.9 "v This letter documents our observations and recommendations for the water feature installed at your residence project located at 15515 — 75"' Place West in Edmonds, Washington. We have been requested by Steve Barnes, your architect to complete this letter in compliance with a request from the City of Edmonds. A water feature has been constructed in the northern region of the site, off the northeast comer of the residential structure. We did not observe installation of the water feature, but have been informed by Steve Barnes, the site architect, of the design and construction. The information provided is that the water feature was constructed with a plastic liner at the base of the feature to prevent water from seeping into the onsite soils. A felt base was also placed below the plastic liner to prevent punctures from subgrade conditions. Any punctures to the water feature plastic liner would be expected from tree branches that fall from the slope above the feature. If this occurs, the puncture should be fixed immediately. 17625 -130th Avenue NE, 0102, Woodinville, WA 98072 • Phone: 425-844-1977 • Fax: 425-844-1987 Water Feature Letter Ron Hilliard Residence Edmonds, Washington Building Permit # 2008-0117 June 19, 2009 CG File No. 2212 Page 2 Based on our observations and discussions with Mr. Barnes, it is our opinion that the water feature will not adversely affect the stability of the sloping conditions at the site. Excess water should not be allowed to enter the subgrade soils from punctures within the base of the pond liner. We trust that this letter meets your needs at this time. If you have any questions or need further clarification, please call. Sincerely, Cornerstone Geotechnical, Inc. Jeff Wale Project Manager L �vs eat r- oL a 24285 'O ��CiS'IR y Charles P. Couvrette, PE Principal Three Copies Submitted JRW:CPC cc: City of Edmonds — one copy . Mr. Steve Barnes, Cornerstone Architectural Group -- one copy Cornerstone Geotechnical, Inc. oa (C-) -NLU ARC POND GAS � P OU/i� G LINE p JS i AND UT1NG DECK�CO�RAGE EVAI P� DFCK'L4 raAMFIG� MASO SE / // /W, 1 ) DECK PATIO I � 1-tot - � 16'x6' i _ - �� TRANS 1 i VAULT 1 ! PEDESTAL 120' �i0NE? i CON POSSIBLE EUTUR--�+�J+� PHONE PEDESTAL - - — 1 1 REMOVE EXISTING I OL P } INSTALL UNDERGR SXSTEM~- -�