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HillcrestBldg1.pdfCity of Edmonds PLAN REVIEW COMMENTS BUILDING DIVISION (425) 771-0220 DATE: October 27, 2006 ) TO: John Kvernmo Fax (425) 259-0799 FROM: Jenny Readwin, Plans Ex in RE: Plan Check # 2006-0184 Project: Hillcrest SFR Project Address: 17008 77th P1 W During review of the above noted revision, it was found that the following information, corrections, or clarifications are needed. Please redline plans or submit two (2) sets of revised plans/documents (affected sheets only) with a written response to each of the above items to a Permit Coordinator. 1) The property is considered a critical area and per our attached retaining wall handout any retaining walls located in a critical area regardless of height require plans and calculations stamped and signed by a Washington State Licensed Professional Engineer. Please submit. ' i 1 city of edmonds development information I. 1$94 Retaining Wall Permit Submittal Requirements PERMIT REQUIRED: A permit is required for retaining walls made of any material (concrete, masonry, ecology block, steel, railroad ties, etc.), unless specifically exempted as described in this handout. Any retaining wall located in a Critical Area or its buffer, or in the designated Earth Subsidence Landslide Hazard area (ESLHA), as defined by the Edmonds Community Development Code, must obtain a permit regardless of height, mass or length. CODES: International Building Code (Current Edition) WSDOT/APWA Standard Specifications for Road, Bridge, & Municipal Construction (Current Edition) ECDC Chapter 18.30, 18.40.020 & 18-70 ECDC Chapters 19.00 & 19. 10, ECDC Chapter 23.80 FEE: Permit fee $265 + $15 City surcharge $50 Per Required City Inspection Some projects may require Peer Review. Additional Peer Review fees are $110 + Cost of Consultant Review to be paid `by the applicant SUBMITTAL REQUIREMENTS (See Page 5) 1. A Critical Areas Determination, issued by the Planning Division (See .Handout #P20) 2. Soils Investigation or Soils Report Three (3) copies, stamped and signed by a Washington State licensed geotechnical engineer or engineering geologist. 3. Grading Plan - Three (3) copies, with yardage calculations 2. Plot Plan -Three (3) copies, scaled I"=20' one of the three plot plans must be no larger 8 !z" x 14") 5. Retaining Wall Section and Elevation Views - Two (2) copies, stamped and signed by a Washington State licensed engineer. 6. Retaining Wall Design Calculations - Two (2) copies, stamped and signed by a Washington State Licensed Engineer 7. Erosion and Sedimentation Control Plan - Three (3) copies 8. For retaining wails in critical areas or in the ESLHA, a letter from the geotechnical engineer addressing the criteria of ECDC 23.80.070. LATEMMUILDINGVIANDOtTC ICODES\RETWAL B62.DOC Revised 7106 Wage i of 8 INTRODUCTION Retaining walls, including shoring structures, are structural systems that provide lateral support for vertical or near -vertical slopes of soil. Several common types of retaining walls include gravity, semigravity, cantilever, soldier pile, sheet pile, proprietary modular block, mechanically stabilized earth, and soil nail retaining walls. The City of Edmonds does not consider rockeries to be retaining walls. See Handout 41363 for specific rockery design and permitting information. HEIGHT DEFINITIONS -See Attached Standard Details E8.11 & E8.12 Wall Height. For permitting purposes, retaining wall height is defined as the height measured vertically from the finished grade at the exposed toe of the retaining wall to the highest point of the wall. Setback Area Height. For setback p_ oses, retaining wall Setback Area Height is defined as the height measured vertically from the original gradc to the highest point of the retaining wall supporting soil. PERMIT REQUIREMENTS A retaining wall permit shall be required when any of the following conditions apply: 1. Retaining walls greater than four (4) feet in height, (see Wall Height definition above). + Plans must be designed (including design calculations) and stamped by a State Licensed Professional Engineer. • Peer review is not required for walls 6 feet or less in height; however, the City reserves the right to require peer review and/or special inspections if a special condition exists. • Peer review is required for retaining walls greater than 6 feet in height and special inspection is required for installation. 2. Retaining walls of any height located within the designated Earth Subsidence Landslide Hazard Area, as. defined by the Edmonds 'Communuity Development Code. • Plans must be designed consistent with ECDC Chapter 23.80 (including design calculations) and stamped by a Washington State Licensed Professional Engineer. • Peer review and special inspection, shall be required (regardless of height). 3. Retaining walls of ga height located in a Critical Area or its buffer. • Plans must be designed consistent with ECDC Chapter 23. 80 (including design calculations) and stamped by a Washington State Licensed Professional Engineer. • The City reserves the right to require peer review and/or special inspections for all retaining walls in critical areas or their buffers. Whenever a retaining wall exceeds 6 feet in height, peer review and special inspections will be required. 4. Retaining walls of any height supRorUpg a_street, road, alley, driveway, barking, building,. structure or other surcharge See attached Standard Detail E8.12.1 9 Plans must be designed (including design calculations) and stamped by a State Licensed Professional Engineer. • The City reserves the right to require peer review and/or special inspections for all retaixdng walls supporting a surcharge. Whenever a retaining wall exceeds 6 feet in height, peer review and special inspections will be required. I,.ITEMP1BL UDINOXHANDOUT ICODEMETWALa6z.DOC Revised 7/06 Page 2 of $ S. Retaining walls of any height, that impound flammable liquids or hazardous materials. * Plans must be designed (including design calculations) and stamped by a State Licensed Professional Engineer. • The City reserves the right to require peer review and/or special inspections for all retaining walls than impound flammable liquids or hazardous materials. Whenever a retaining wall exceeds 6 feet in height, peer review and special inspections will be required. 6. Terraced retaining walls are permitted subject to the noted conditions above (1-5). • Each retaining wall tier is considered to be a separate retaining wall. If any individual tier requires a permit then a permit is required. • The upper retaining wall tier shall be setback from the lower retaining wall tier a distance equal to or greater than the height of the lower retaining wall tier. See attached Standard Details E8.12 and E8.12.1. + If the distance between the upper retaining wall tier and the lower retaining wall tier is less than the height of the lower tier then the lower tier shall be considered to support a surcharge from the upper tier and a permit shall be required per paragraph 3 above. EXEMPTIONS FROM PERNUT REQUIREMENTS A retaining wall permit is not required for the following retaining wall conditions: 1.. Retaining walls four (4) feet or less in height, are exempt from permit requirements provided that none of the conditions above (1-6) apply. See Wall Height definition above. 2. For retaining walls proposed for construction as part of a subdivision or short plat, a separate retaining wall permit is not required. Approval of the subdivision/short. plat civil drawings will constitute approval of retaining walls. However, such retaining walls shall be designed, reviewed and approved based on the requirements of this handout. GENERAL REQUIREMENTS . 1. Retaining walls of any height shall not be constructed in, on, or over (developed or undeveloped) City right-of-way unless specifically approved by the City Engineer, Per Edmonds Community Development Code (ECDC) 18.74 approval of an Encroachment Permit may be granted to locate a retaining wall within the City right-of-way if it does not interfere with the public's use of the right-of-way and/or if the proposal benefits the public interest, safety or convenience (See Handout M26). 2. Retaining walls of any height shall not be constructed over public utility easements, or be constructed to adversely affect drainage, or create a site distance hazard. 3. Retaining walls shall not exceed three (3) feet in height, above original grade, when located in setback areas. See Setback Area Height definition above. 4. Temporary Spoil. Unless permitted by the Geotechnical Engineer of record, temporary spoil or stockpiling shall be placed no closer than two (2) feet from the surface edge of the excavation, measured from the nearest base of the spoil to the out. Spoil should be placed so that it channels rainwater and other Tun. -off water away from the excavation. Permanent spoils are considered to be fill and are subject to IBC requirements. 5. All retaining wall proposals that require a permit shall be stamped and signed by a Washington State Licensed Professional Engineer, including the design calculations. 6. A two (2) foot minimum shy distance shall be maintained from retaining walls to the edge of roads and driveways. LATEMY1BU1LD1NaffANDOUT ICODESIRETWAL B62.DOC Revised 7106 Page 3 of 9 7. The slope behind the top of a retaining wall shall be no steeper than 2:1 (horizontal:vertical). See City of Edmonds standard details E 8.11 and E 8.12 attached. GENERAL INSPECTION REQUMMENTS a If the retaining wall is located on private property and is permitted as part of a building permit or as a separate retaining wall permit, the property owner must call for the required Building Inspections to include but not be limited to: location, setbacks, rebar placement, concrete placement for concrete design strength (f c) of not less than 2500psi, drainage and final inspection. s If the retaining wall is constructed as part of a subdivision/short plat site improvement the property owner must call for the required Engineering Inspections. SPECIAL INSPECTION REQUIREMENTS • The Geotechnical Engineer of record shall verify conformance with the project specific retaining wall design including but not limited to; soil bearing conditions and capacity, groundwater conditions, verification of backfill material, compaction methods, drainage, and retaining wall placement procedures, etc. • The Engineer shall also monitor and provide corrective action recommendations as needed. • Field reports shall be submitted to the Building Division for review and approval for private individual lot development. For retaining walls constructed as part of subdivision/short plat site improvements or in the City right of way (if specifically approved by the City Engineer), field reports shall be submitted to the Engineering Division for review and approval. LITBWOUILDINCT kNDOUr ICODESIRETWAL B62.DOC Revised 1/46 Page 4 of 8 PERMIT SUBMITTAL REQUIREMENTS 1. CRITICAL AREAS CHECKLIST (See Handout #P20) A Critical Areas Determination, issued by the Planning Division, must be completed and on file with the City. Provide applicable information as indicated by the decision. 2. SOILS INVESTIGATION OR SOILS REPORT The classification of soil and design bearing capacity must be determined and called out on the plans based on observation and tests of the soil materials disclosed by borings or excavations performed by a Washington State Licensed Professional Geotechnical Engineer or Engineering Geologist. Soils report recommendations shall be incorporated into the retaining wall design and shall conform to the requirements of IBC 1802 and 13C Table 1804.2. Lots with retaining wall proposals located in the designated Earth Subsidence Landslide Hazard Area are subject to City Ordinance #2661 and Chapter 19.10 of the ECDC. 3. GRADING PLAN Three (3) copies, scaled 1"=20' (See Handout #1337) When fill or grading for the retaining wall exceeds 50 cubic yards, a grading plan with yardage calculations must be submitted (additional permit fees shall be assessed). Exception: Grading in designated Critical areas or within the designated Earth Subsidence and Landslide Hazard Area requires plans, review and additional permit fees regardless of the amount of grading or fill. The grading plan must show existing grade contours and proposed finished grades at two (2) foot intervals for lots with slopes of up to 15%. For lots with 15% slope or greater show all grades at five (5) foot intervals. Clearly define grading limits and trees to be removed and/or retained. Detail permanent slope protection, indicate setbacks from top and toe of slopes, the slope of the lot and methods for temporary and permanent erosion control. Provide calculations and specify the number of cubic yards to be removed, filled, or graded. NOTE: When grading exceeds 499 cubic yards, an Environmental Checklist and APO list must be submitted for SEPA review, (a separate fee is required for grading and for SEPA review). 4. PLOT PLAN Three (3) copies, scaled 1"=20', one of the three plot plans must be no larger than 8 1/2" x 14" with the following: (See Handout #B57) a) North arrow, property line dimensions, streets, alleys, driveways, parking areas, etc. b) Clearly show edge of City right-of-way, curb, gutt(-,r, sidewalk, street trees, etc. c) Detail public and private access and utility easements that encumber the property. *Provide copies of all recorded easements d) Show location of existing house, garage, decks, easements, etc. on the subject property. e) Show location of streams, creeks, drainage courses, etc. on the subject property. 1} Clearly show the proposed location of the retaining wall and distance to property lines. ..g) Indicate the height of the retaining wall, including top and bottom elevations of the wall at five (5) foot linear intervals to clearly show height of the retaining wall along its entirety. h) Show existing and proposed grade contours at two (2) foot linear intervals for slopes up to 15% and five (5) foot linear intervals for slopes exceeding 15%. 5. SECTION AND ELEVATION VIEWS Two (2) copies, stamped and signed by a Washington State licensed engineer, with the following: a) Provide a typical section view of the retaining wall. See City of Edmonds standard detail E 8.11 or E 8.12. LATEMPIBUILD MMIANDOUT ICODESUZETwAL E62.DOC Revised 9106 Page 5 of 8 b) Show footing detail; specify width, maximum height, reinforcing steel schedule, rebar spacing, etc. c) Wall detail; specify width, height, steel schedule, etc. d) Drainage provisions behind wall (piping size and material) and backfill proposed. See City of Edmonds standard detail E 8.11 and/or E 8.12. 6. RETAINING WALL DESIGN CALCULATIONS Retaining walls are required W be designed by a Washington State Licensed Professional Engineer. a) Provide two (2) copies of the stamped and signed design calculations. • Design Calculations shall include; soils classification, unit weight of soil, allowable bearing pressure, active and passive earth pressures, liquefaction potential, coefficient of friction, seismic loads, site specific surcharge loads, water table information, grading calculations, global slope stability, sliding resistance, overturning, local capacity of walls (bending, shear, deflection, embedment), lagging design and fascia design. b) For manufactured systems (i.e., block walls, and other engineered retaining wall systems) provide the installation instructions with the permit application submittal. 7. EROSION AND SEDIMENTATION CONTROL PLAN Submit three (3) Erosion and Sedimentation Control Plans per ECDC 18.30. See City of Edmonds standard details E 1. 1, E 1.1.1. and E 1. 3, attached. 8. LETTER FROM GEOTECHNICAL ENGINEER REGARDING ECDC 23.80.070. For retaining walls in critical areas or in the ESLHA, su'bn-dt a letter from the geotechnical engineer addressing the criteria of ECDC 23.80.070. NOTE: THE PURPOSE OF THIS HANDOUT IS TO ASSIST THE PUBLIC IN COMPLYING WITH DETAILED PERMIT SUBMITTAL RE LUYlyIENTS. IT IS NOT A COMPLETE LIST OF PERMIT OR CODE REQUIREMENTS AND SHOULD NOT BE USED AS A SUBSTITUTE FOR APPLICABLE LAWS AND REGULATIONS. IT IS THE RESPONSIBILITY OF THE OWNERMESIGN PROFESSIONAL TO REVIEW THE SUBMITTAL FOR COMPLETENESS AND APPLICABILITY TO OTHER CODES, ONLY COMPLETE APPLICATIONS WILL BE ACCEPTED BY THE CITY FOR REVIEW. L:ITEIV MUILDINGIHANDOUT ICODESIRBTWAL B62.DOC Revised 7106 Page 6 Of 8 DESIGN CRITERIA FOR RETAINING WALLS General There are two types of retaining walls; one type is protecting, typically used for soils that are capable of standing by themselves without support and the other type is retaining or supporting, for soils that are not capable of standing or remaining at the existing slope. -Retaining walls shall be designed based on standard engineering methods provided by the International Building Code and WSDOT/APWA Standard specifications for Road., Bridge, and Muncipal Construction (current edition). Width and height of footings and walls shall be provided, including a reinforcing steel schedule and design calculations. At a minimum, gravity block and modular block walls shall meet the requirements of the installation design standards described herein and reflected in the diagrams. See City of -Edmonds standard details attached. All other types of retaining walls not described within this document shall conform to the requirements of the International Building Code and shall meet the current professional standard of care for retaining wall design. Design Considerations The submitted plans, specifications, engineering calculations, diagrams, soils report, and other data shall conform to the requirements of the current edition of the International Building Code but not be limited to, the requirements of IBC chapter 1806. Wall Backfill For gravity and modular block retaining walls, the material located directly behind the wall shall conform to the manufacturer's recommendations or plans and specifications prepared by the Engineer of Record. if there is no manufacturer's recommendation or plans and specifications prepared by the engineer of record, the wall backfill shall consist of well draining granular material in conformance with WSDOT/APWA 9- 03.12(2). Sieve Size Percent Passing 4" Square 100 2" Square 75-100 US No. 4 22-66 US No. 200 5.0 Max Dust Ratio: hydrostatic pressure on the wall. The intercepted % Passing US No. 200 100 --- 2/3 max % Passing US No. 40 80 Sand Equivalent 52 min Gravel Backfill for Drains A system shall be designed to intercept ground water behind the retaining wall in order to prevent Sieve Size Percent Passi hydrostatic pressure on the wall. The intercepted 1" Square 100 --- groundwater shall be channeled to an approved 3f4" Square 80 100 drainage system. Specify all drainage materials 318" Square 10 40 (piping, type of backfill, etc.) on the drainage plan; USNo. 4 0 4 note the backfill that surrounds the drainage pipe shall US No. 200 p 2 conform to WSDOT/APWA 9-03.12(4) outlined below: This material shall be placed to a twelve (12") inch minimum width between the entire block facing and the cut slope. L:ITEMP%LTILDINGIIIANDOLIT ICODESIRETWAL S62.DOC Reviscd7/06 Page 7 of 8 RETAINING WALL_ CONSTRUCTION For gravity block and modular block retaining walls, the contractor shall follow the manufacturer's recommended installation procedure. For all other types of retaining walls, the contractor shall follow the plans and specifications prepared by the Engineer of Record. Keyway The Engineer of record shall determine the minimum embedment for all walls in accordance with the manufacturer's recommendation or as required by the International Building Code. Wall Backfill For gravity and modular block retaining walls, the backfill material shall be placed in lifts to an elevation approximately six (6) inches below the top of each course of blocks, until the uppermost course is placed. Any backfill material on the bearing surface of one block course shall be removed before setting the next course. For all other types of retaining walls, the contractor shall follow the approved plans and specifications prepared by the Engineer of Record. Backfilling When fill is placed behind a retaining wall, the soil parameters for design are based on the knowledge of the proposed fill soils and the anticipated control of the compaction. Special inspection by a licensed gcotechnical engineer is required to verify that the soils and compaction procedures are proper and the compacted soils properties achieve the design parameters. Underdrain A minimum six (6) -inch diameter rigid perforated or slotted drainpipe shall be placed in a shallow excavated trench located along the backside of the retaining wall, The pipe shall be placed on and surrounded by "Gravel Backfill for Dxains" to a minimum height of V-6" above the bottom of the pipe. A filter fabric shall surround the gravel backfill and shall have a minimum P-0" overlap along the top surface of the gravel. The Engineer may waive this requirement for fabric if shown that soils and water conditions make it unnecessary. The perforated drainpipe shall be connected to the storm drainage system (other than detention) or an approved outfall .Terraced Retaining Walls Each tier of the terraced retaining wall shall be installed in accordance with the prescriptive installation design, standards described herein and reflected in the diagrams on the project specific plans and specifications prepared by the Engineer of Record. For gravity block and modular block retaining walls installed in accordance with the prescriptive design standards described herein, the upper retaining wall, tier shall not be located within a horizontal distance from the lower retaining wall tier equal to the height of the lower retaining wall. LATBMPSUILDING\RANDOUT KODEMETWAL B62.DOC Revised 7106 Page 8 of 8