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HomeMy WebLinkAboutLUA17000565_EXHIBITS4,800 400 WGS_1984_Web_Mercator_Auxiliary_Sphere Neighborhood Map This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. THIS MAP IS NOT TO BE USED FOR NAVIGATION Notes Rhododendron Ridge Stormwater Extension Legend 272 0 136 272 Feet Information Technology - GIS RentonMapSupport@Rentonwa.gov 06/21/2017 City and County Boundary Other City of Renton Parcels 205210215220225230235240205210215220225230235240PROPOSEDGRADE, TYP.15.18'DEPTHTOP OF VAULTELEV. = 226.50BOT OF VAULTELEV. = 208.006" AVG. SEDIMENTSTORAGE DEPTH6" GRAVEL BEDBOT OF STORAGEELEV. = 209.00100 YR. W.S.ELEV = 224.68LIMIT OFEXCAVATION1'LIMIT OFEXCAVATION1'1'1'2' - 10'COVER21 L F 12 " SD @ 18 .61%SD #4TYPE I-54 MHRIM = 237.86I.E. 12" OUT (W) = 228.00200205210215220225230235240TOP OF VAULTELEV. = 226.50BOTTOM SUMPELEV. 204.00BOT OF STORAGEELEV. = 209.006" AVG. SEDIMENTSTORAGE DEPTH100 YR. W.S.ELEV = 224.68PROPOSEDGRADE, TYP.2' - 10'COVERLIMIT OFEXCAVATION15.18'DEPTHLIMIT OFEXCAVATION1'1'1'1'BOT OF VAULTELEV.= 208.007 : 10.82' FREEBOARDEND OF PAVING ELEV. = 229.14 START OF PAVING ELEV. = 236.68 SD #3TYPE II-48 CBw/ SOLID LOCKING LIDRIM = 218.94I.E. 12" OUT (SW) = 207.6277 LF 12" SD @ 0.50%GRAVEL ACCESSROADOHUOHUOHUOHUXXXXXXXX X X X X X X X X X X X X X X X X X X X X X X RDRDRDRDRDRDRDRDRDRDRDRDRDRD RDRDRD DETENTION VAULT 30' ROW112TH AVENUE NE (UNIMPROVED ROW)10' BUFFERSTORMFILTER FORWATER QUALITYTREATMENT , SEEDETAIL SHT. SD-212' WIDEMAINTENANCEACCESS15% MAX SLOPE20' TRACT240242 2602 5 6 256258258244 SD #6, TYPE II-54 MHw/ SPILL CONTROLSTA. 0+30.00, 3.00' LRIM = 256.27I.E. 12" N-12 IN (NE) = 249.00I.E. 12" N-12 OUT (W) = 249.0045 LF 12"@ 2.64%75 LF 12" @ 22.44%21 LF 12"@ 18.61%77 LF 12" @ 0.50%107 LF 12" @ 3.27%SD #3, TYPE II-48 CBw/ SOLID LOCKING LIDSTA. 6+97.12, 0.00'RIM = 218.94I.E. 12" N-12 IN (N) = 207.62I.E. 6" PVC FD IN (N) = 208.12I.E. 12" N-12 OUT (SW) = 207.62SD #4, TYPE I-54 MHRIM = 237.86I.E. 12" N-12 IN (E) = 228.00I.E. 6" PVC RD IN (N) = 228.50I.E. 12" N-12 OUT (W) = 228.002202302182222242262282322342362 3 0228218 240250SD #2A, TYPE I CBw/ SOLID LOCKING LIDSTA. 6+40.67, 0.00'RIM = 207.43I.E. 12" N-12 IN (NE) = 204.00I.E. 12" HDPE SDR-11 OUT (W) = 204.0056 LF 12" @ 6.41%200205210215220225230235240SE 80TH ST.SE 80TH STREET(UNIMPROVED ROW)RHODODENDRON RIDGEREV NO.DATEDESCRIPTIONMADE BYCHECKEDKING COUNTYERP PLAN SETPLOTTED:SHEETJOB NO. 14134iCAP RHODY RIDGE, LLCCITY OF NEWCASTLEWASHINGTONSE 1/4, SE 1/4 SECTION 29, TOWNSHIP 24 N, RANGE 5 E, W.M.CITY OF NEWCASTLE, KING COUNTY, WASHINGTONDRAWN:APPROVED:DESIGNED:BPF, SPKJGAPPROVED FOR CONSTRUCTIONDATE:BY:CITY OF NEWCASTLETHESE DRAWINGS ARE APPROVED FOR CONSTRUCTION FOR A PERIOD OF 12MONTHS FROM THE DATE SHOWN HEREON. THE CITY RESERVES THE RIGHTTO MAKE REVISIONS, ADDITIONS, DELETIONS, OR MODIFICATIONS SHOULDCONSTRUCTION BE DELAYED BEYOND THIS TIME LIMITATION. THE CITY, BYAPPROVING THESE DRAWINGS, ASSUMES NO LIABILITY IN REGARDS TOTHEIR ACCURACY OR OMISSIONS.M:\ACAD\PLATS\14\14134\Infrastructure ERP\14134H01.dwg6/19/17 18:04SpasztorSPKnow what'sbelow.before you dig.CallR6/7/17VAULT SECTION A-ASCALE: 1"=10' HOR. 1"=5' VER.VAULT SECTION B-BSCALE: 1"=10' HOR. 1"=5' VER.DETENTION VAULT PLAN & SECTIONSD-1121314TRACT D(ACCESS)15AABB21'21'136' 136'EXCAVATION LIMIT AT1:1 SLOPE, TYP.SHORING REQUIRED FORTREE PROTECTION, TYP.EXCAVATION LIMITBEGINS 3' OFFSETFROM VAULT.VAULT ACCESS1)ACCESS RISERS ARE 48" DIAM. M.H. w/ ECCENTRIC CONE TOPSECTIONS AS NECESSARY (2'EC = 2' HIGH SECTION; 3'EC = 3'HIGH SECTION) OVER MIN. 2' DIAM. HOLE IN VAULT PANELS ORGRADE RINGS (GR). PROVIDE LADDER OR STEPS TO BOTTOM OFVAULT PER DETAIL SHT. SD-2.2)PROVIDE ROUND LOCKING MANHOLE COVERS FOR ALL ACCESSRISERS.3)5'x10' REMOVABLE LOCKING PANEL SHALL MEET THE 2009KCSWDM REQUIREMENTS.VAULT VENTILATION1) 1'-1" DIAM. VENT OPENINGS ARE DETAILED ON THE STRUCTURALPLANS.2) VENTS IN PARK/LANDSCAPE AREAS SHALL BE 12" DIAM. IPS SCH40 PVC PIPE (OR EQUAL) WITH LIGHT DUTY DROP-IN GRATES.3) VENTS IN PAVED AREAS SUBJECT TO VEHICULAR TRAFFIC SHALLBE 12" DIAM. CLASS 50 DUCTILE IRON PIPE w/ 12" DIAM. CASTIRON RING AND COVER (OLYMPIC FOUNDRY, INC. PART NO. MH5,OR EQUAL) w/ 2' SQUARE x 1' DEPTH CONC. CL. 5(S) COLLAR.CONTROL RISER INVAULT, SEE DETAILSHT. SD-2VAULTOUTLET= 208.0013" DIA. VENT OPENINGS,TYP.2 TOTALFG 235.1TV 226.5VAULT ACCESSCOVERFG 236.8TV 226.5w/ ECVAULT ACCESSCOVERFG 239.4TV 226.5w/ ECVAULT ACCESSCOVERFG 235.7TV 226.5w/ ECVAULT INLETIE = 224.68060401020SCALE: 1" = 20'SEE SHT. SD-3FOR OUTFALL RHODODENDRON RIDGEREV NO.DATEDESCRIPTIONMADE BYCHECKEDKING COUNTYERP PLAN SETPLOTTED:SHEETJOB NO. 14134iCAP RHODY RIDGE, LLCCITY OF NEWCASTLEWASHINGTONSE 1/4, SE 1/4 SECTION 29, TOWNSHIP 24 N, RANGE 5 E, W.M.CITY OF NEWCASTLE, KING COUNTY, WASHINGTONDRAWN:APPROVED:DESIGNED:BPF, SPKJGAPPROVED FOR CONSTRUCTIONDATE:BY:CITY OF NEWCASTLETHESE DRAWINGS ARE APPROVED FOR CONSTRUCTION FOR A PERIOD OF 12MONTHS FROM THE DATE SHOWN HEREON. THE CITY RESERVES THE RIGHTTO MAKE REVISIONS, ADDITIONS, DELETIONS, OR MODIFICATIONS SHOULDCONSTRUCTION BE DELAYED BEYOND THIS TIME LIMITATION. THE CITY, BYAPPROVING THESE DRAWINGS, ASSUMES NO LIABILITY IN REGARDS TOTHEIR ACCURACY OR OMISSIONS.M:\ACAD\PLATS\14\14134\Infrastructure ERP\14134H02.dwg6/19/17 18:06SpasztorSPKnow what'sbelow.before you dig.CallR6/7/17DETENTION VAULT CONTROLSTRUCTURE DETAILNOTE:SEE FLOW RESTRICTOR DETAIL SW-18FOR ADDITIONAL REQUIREMENTS.ROUND SOLID COVERWITH LOCKING BOLTS100 YR. W.S. ELEV = 224.68TOP OF VAULTELEV = 226.50ORIFICE NO. 2, ELEV. = 220.20ORIFICE DIA. = 1.15"ORIFICE NO. 2, ELEV. = 215.50ORIFICE DIA. = 1.20"FLOOR GRATE WITH 2'X2' ACCESS DOOR(1"x1/4" GALVANIZED METAL BARS)18" RISERPIPE SUPPORTSPER C.O.N. DETAIL SW-18CLEANOUT GATE: SHEAR GATE WITHCONTROL ROD, PER C.O.N. DETAIL SW-18INSIDE TOP OF VAULTELEV = 225.50ORIFICE NO. 1, ELEV. = 206.00ORIFICE DIA. = 1.10"BOT OF VAULTELEV. = 208.00INSIDE BOT OF VAULTELEV. = 209.00KNOCKOUT DIA.= WALLTHICKNESS + PIPE O.D.ORIFICE ELBOWPER C.O.N. DETAILSW-1812" OUTLETI.E. = 208.00SEE STRUCTURAL PLANS FORSUMP AND FOOTING DESIGNVAULT WALLDESIGN BY OTHERS3' COVERMINIMUM18" RISER ELEV. = 224.502.0'5.5'2.0'SEDIMENT STORAGEELEV. = 209.501' SECTION OF 18" PIPE ATTACHED BYGASKETED BAND TO ALLOW REMOVAL.PER C.O.N. DETAIL SW-185.5' x 4' x4' SUMPELEV. = 204.00STORM DETENTION VAULTCONTROL STRUCTURESCALE: 1" = 2'NOTCH 1" WIDEBTM ELEV = 224.00VAULT ACCESS DETAILPER STRUCTURAL PLANSSEE SHT. SD-3 FOROUTFALL PROFILE SSSSSSSSSSXXSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSWSDSDWWWWEOHUOHUOHUOHUSDWSDSSSSSSWWWDSXXXXXXXXXX X X X X XWWWWWW 1514SD #3, TYPE II-48 CBw/ SOLID LOCKING LIDSTA. 6+97.12, 0.00'SD #2, TYPE II-48 CBw/ SOLID LOCKING LIDSTA. 0+49.45, 0.00'EXIST. SD #1, TYPE I CBSTA. 0+00.00, 0.00'SD #2A, TYPE I CBw/ SOLID LOCKING LIDSTA. 6+40.67, 0.00'34LF 18" N-12 @ 1.16%2040608010012014016018020022020406080100120140160180200220SD #3, TYPE II-48 CB w/ SOLID LOCKING LID STA. 6+97.12, 0.00' . RIM = 218.94 I.E. 12" IN (N) = 207.62 I.E. 6" IN (N) = 208.12 I.E. 12" OUT (SW) = 207.62 EXIST. SD #1, TYPE I CB STA. 0+00.00, 0.00' . RIM = 57.94 I.E. 18" IN (S) = 54.84 I.E. 12" OUT (NW) = 54.84 SD #2, TYPE II-48 CB w/ SOLID LOCKING LID STA. 0+49.45, 0.00' . RIM = 62.41 I.E. 18" IN (E) = 53.04 I.E. 18" OUT (W) = 56.04 SD #1, TYPE I CB CONNECT TO EXISTING CITY OF RENTON STORM AT EXIST. 12" CULVERT STA. 0+34.45, 0.00' . RIM = 58.47 I.E. 18" IN (E) = 55.24 I.E. 12" IN (S) = 55.74 I.E. 18" OUT (N) = 55.24 BEGIN PIPE BENDAND BURY PIPE AT SURFACE.STA. 0+83, IE = 66.1±DAYLIGHT PIPE TO SURFACE. IE = 202.5±, STA. 6+05.5 SD #2A, TYPE I CB w/ SOLID LOCKING LID STA. 6+40.67, 0.00' . RIM = 207.43 I.E. 12" IN (NE) = 204.00 I.E. 12" OUT (W) = 204.00 56 LF 12"SD @ 6.46%35 LF 12"SD @ 4.29%15 LF 18"SD @ 5.33%50.0%77 LF 12"SD @ 0.50%12.4%18.6%24.0%34.3%32.7%25.6%28.7%29.4%35.8%28.4%19.5%14.4%DETENTION VAULTSLIDE 7.5' LENGTH OF 12" PIPEINTO 10' LENGTH OF 18" PIPE@ STA. 0+98, IE = 68.2±PIPE ANCHORS 10' O.C.VERTICAL SPACING PERDETAIL THIS SHEET, TYP.PIPE ANCHORS 10' O.C.VERTICAL SPACING PERDETAIL THIS SHEET, TYP.EXIST . 8 ' SS0+000+400+801+201+602+002+402+803+203+604+004+404+805+205+606+006+406+807+207+608+008+4057.9 60.2 65.8 72.6 81.9 94.0 106.8 119.5 129.7 141.6 154.4 168.0 181.1 189.4 196.0 201.7 207.4 216.7 223.9 225.8 226.2 57.90 60.24 65.83 72.62 81.88 94.00 106.79 119.53 129.72 141.63 154.43 168.03 181.09 189.44 196.04 201.72 207.35 216.66 223.86 225.78 226.23 SE 80TH STREET(UNIMPROVED ROW)112TH AVENUE NE(UNIMPROVED ROW)110TH AVENUE NELINCOLN AVE.NESE 80TH STREET(UNIMPROVED)SIGNED "NE 43rd STREET" IN RENTON60' ROWCITY OF NEWCASTLECITY OF RENTONCITY OF NEWCASTLECITY OF RENTONFLOW CONTROL STRUCTUREI.E. 12" OUT = 208.00SEE POND OUTFALLSHT. SD-1 FOR DETAIL.0120802040SCALE: 1" = 40'STORM DRAIN OUTFALL PROFILESCALE: 1" = 40' H 1" = 20' VDAYLIGHT PIPE TO SURFACE@ STA. 6+05.5IE = 202.5±END PIPE ON SURFACEAND BURY UNDERGROUND@ STA. 0+83, IE = 66.1±500 LF 12" HDPE SDR-11 PIPE ONSURFACE. PIPE INSTALLED BETWEENCLEARING LIMITS TO AVOID TREES.500 LF 12" HDPE SDR-11 PIPEON EXISTING GRADE, TYP.CB #1, TYPE 1CONNECT TO EXISTING CITY OF RENTONSTORM AT EXIST. 12" CULVERT, SEEPROFILE BELOW FOR DETAIL.RHODODENDRON RIDGEREV NO.DATEDESCRIPTIONMADE BYCHECKEDKING COUNTYERP PLAN SETPLOTTED:SHEETJOB NO. 14134iCAP RHODY RIDGE, LLCCITY OF NEWCASTLEWASHINGTONSE 1/4, SE 1/4 SECTION 29, TOWNSHIP 24 N, RANGE 5 E, W.M.CITY OF NEWCASTLE, KING COUNTY, WASHINGTONDRAWN:APPROVED:DESIGNED:BPF, SPKJGAPPROVED FOR CONSTRUCTIONDATE:BY:CITY OF NEWCASTLETHESE DRAWINGS ARE APPROVED FOR CONSTRUCTION FOR A PERIOD OF 12MONTHS FROM THE DATE SHOWN HEREON. THE CITY RESERVES THE RIGHTTO MAKE REVISIONS, ADDITIONS, DELETIONS, OR MODIFICATIONS SHOULDCONSTRUCTION BE DELAYED BEYOND THIS TIME LIMITATION. THE CITY, BYAPPROVING THESE DRAWINGS, ASSUMES NO LIABILITY IN REGARDS TOTHEIR ACCURACY OR OMISSIONS.M:\ACAD\PLATS\14\14134\Infrastructure ERP\14134H03.dwg6/20/17 11:12SpasztorSPKnow what'sbelow.before you dig.CallR6/7/17LNEMSD-3OFF-SITE STORM DRAIN OUTFALLINSTALL HIGH VISIBILITYRIBBON ALONG EXISTINGCLEARING LIMITS, TYP.INSTALL INLET PROTECTION ONEXISTING CATCH BASINS WITHIN200' OF PROJECT, TYP.SLIDE 7.5' LENGTH OF 12" PIPEINTO 10' LENGTH OF 18" PIPE@ STA. 0+98, IE = 68.2±PIPE ANCHORS 10' O.C.VERTICAL SPACING PERDETAIL THIS SHEET, TYP.12" HDPE SDR-1118" HDPE SDR-1115' LF7.5' LFSLIDE 7.5' LENGTH OF 12" PIPEINTO 15' LENGTH OF 18" PIPE.SLIEVE CONNECTION DETAILNTSBURY PIPE AT END OFSLIEVE PER PLAN.18" N-12OUT18" HDPESDR-11 INIE 18" IN = 53.04IE 18" IN = 56.04(SEE MANUFACTURERHDPE CONNECTION DETAILN.T.S.HDPE PIPENOTE: CONTRACTOR SHALLSUBMIT SHOP DRAWINGS PRIORTO CONSTRUCTION.PROVIDE CONCRETE SUPPORTWALL, FULL DEPTH WITH AMINIMUM OF 12" AROUND TOPAND SIDES12"12"PROVIDE RUBBER O-RINGGASKETS AROUND 36" HDPEHDPE FLANGE ADAPTER6"4 EA. # 6 REBARAS SHOWN2" MIN.CLR.GROUT SHALL BE MASTERFLOW928 EXTENDED WORK-TIMENONSHRINK GROUT OR EQUAL.INSTALL PER MANUFACTURER'SRECOMMENDATIONS Kirkland Office | 911 Fifth Avenue | Kirkland, WA 98033 P | 425.827.7701 F| 425.827.5424 Everett Office | 2911 ½ Hewitt Avenue, Suite 2 | Everett, WA 98201 P | 425.259.0522 F | 425.827.5424 Tacoma Office | 1552 Commerce Street, Suite 102 | Tacoma, WA 98402 P | 253.722.2992 F | 253.722.2993 www.aesgeo.com May 26, 2016 Revised June 7, 2016 Project No. KE160152A iCap Rhody Ridge, LLC 3535 Factoria Boulevard SE, Suite 500 Bellevue, Washington 98006 Attention: Mr. Levi Rowse Subject: Geologic Document Review and Site Reconnaissance Rhododendron Ridge 11230 SE 80th Street Newcastle, Washington Dear Mr. Rowse: This letter presents the results of Associated Earth Sciences, Inc.’s (AESI’s) site reconnaissance for the property referenced above at 11230 SE 80th Street in Newcastle, Washington. The site reconnaissance was performed in general conformance with AESI’s scope of work outlined in our proposal dated March 30, 2016. Our study was intended to provide information regarding the proposed residential development, particularly the proposed storm drainage outfall to be constructed as a surface-mounted HDPE pipe leading down a steeply sloping, unimproved portion of the City of Renton right-of-way for SE 80th Street. PROJECT DESCRIPTION The subject site is the existing residential property located at 11230 SE 80th Street in Newcastle, Washington (King County Parcel Nos. 334330048-0, -2, -3). We understand that the proposed project includes 15 residential lots, with associated grading, access, and utilities, including a proposed storm drainage outfall to be constructed as a surface-mounted HDPE pipe leading Rhododendron Ridge Geologic Document Review Newcastle, Washington and Site Reconnaissance May 26, 2016; Revised June 7, 2016 ASSOCIATE EARTH SCIENCES, INC. JPL/ld – KE160152A3 – Projects\20160152\KE\WP Page 2 down a steeply sloping, unimproved portion of the City of Renton right-of-way for SE 80th Street. We understand that the City of Renton has required a geologic reconnaissance of this slope to provide an opinion regarding the suitability of the proposed outfall configuration. The purpose of AESI’s study is to perform a site reconnaissance down the sloping portion of the SE 80th Street right-of-way to provide our opinion regarding stability or erosion issues along the drainage alignment under current conditions, given the proposed surface-mounted drain system. Also, our study includes review of available information, including past explorations, wetland delineations by others, and Light Detection and Ranging (LiDAR) imagery, to provide an opinion regarding the overall stability of the subject site and the slopes leading down to the west, given the proposed improvements. As part of a previous study, AESI observed an exploration boring advanced in the area of the northwest corner of the subject site. Also, for our use in preparing this letter, we have been provided with “Geotechnical Engineering Study – Rhododendron Ridge,” prepared by Earth Solutions NW, LLC (Earth Solutions) and dated January 29, 2015, which documented explorations completed by others at the subject site. RESEARCH RESULTS In addition to performing our site reconnaissance, AESI researched available published geologic, soils, and ground water information about the site and area immediately adjacent to the property. The resources that we consulted were: • King County Website (iMAP) • Previous geotechnical reports by AESI and others (see below) • U.S. Geological Survey (USGS) Geologic Maps Site geology and geomorphology were formed from glacial depositional processes and subsequent erosion to form the current topographic landforms. The results of our research are presented below. Aerial Photograph Review Non-stereographic aerial photographs available from iMAP were reviewed for the site. We reviewed selected photographs taken from 1936 to 2013. The objective for the aerial photograph review was to determine the general history of development in the vicinity of and within the site. Rhododendron Ridge Geologic Document Review Newcastle, Washington and Site Reconnaissance May 26, 2016; Revised June 7, 2016 ASSOCIATE EARTH SCIENCES, INC. JPL/ld – KE160152A3 – Projects\20160152\KE\WP Page 3 • 1936 - This black and white photograph indicates that the subject site, along with the SE 80th Street right-of-way and the slopes to the west of the subject site, is vegetated with what appear to be deciduous trees and shrubs. Several rows of orchard trees are located to the east of the subject site. There are no obvious indications of slope instability on the site. However, the resolution of the photograph is low. • 1998 - This black and white photograph indicates that the current residence exists, along with vegetated garden areas (rhododendrons?), and the slope to the west is vegetated with what appear to be deciduous trees and shrubs. A multifamily residential development is located below the slope to the west. There are no obvious indications of slope instability on the site. However, the resolution of the photograph is low. • 2000 - This color photograph indicates no noticeable changes from the 1998 photograph. The coloring suggests both deciduous and evergreen trees are present on the slope. There are no obvious indications of ground water seepage, erosion, or slope instability on the site. However, as with the 1998 photograph, the resolution of the photograph is relatively low. • 2002 - The resolution of this photograph is good in comparison with the 1998 and 2000 photographs. This color photograph indicates no obviously noticeable changes from the 2000 photograph. Both evergreen and deciduous trees are present on the western slope. There are no obvious indications of ground water seepage, erosion, or slope instability on the site. • 2005, 2007, and 2009 - The resolution of these photographs is good in comparison with the previous photographs. These color photographs indicate no obviously noticeable changes at the subject site from the 2000 or 2002 photographs. The residential plat to the east of the subject site was constructed during this time, along with an improved SE 80th Street segment leading to the east of the site. There are no obvious indications of ground water seepage, erosion, or slope instability on the site. • 2012 and 2013 - The 2012 photograph appears to have been taken in early spring, and many of the deciduous trees are bare, allowing for a somewhat better view to the forest floor along the slopes to the west of the subject site. The 2013 photograph includes fully leafed deciduous trees. There are no obvious indications of ground water seepage, erosion, or slope instability on the site. Rhododendron Ridge Geologic Document Review Newcastle, Washington and Site Reconnaissance May 26, 2016; Revised June 7, 2016 ASSOCIATE EARTH SCIENCES, INC. JPL/ld – KE160152A3 – Projects\20160152\KE\WP Page 4 Topography/Geomorphology The topographic maps and LIDAR imagery available on iMAP indicate gently to moderately sloping terrain within the subject site, and moderately to steeply sloping terrain to the west. Based on our review of the LIDAR image, the slopes leading upward from the area of Lake Washington to the upland encompassing the subject site include several bowl-shaped slide features, including to the immediate north and south of the subject site. These features are shown in Figure 1. However, based on our review of the above-mentioned aerial photography and the conditions observed during our site reconnaissance, it is our opinion that the landslide scarps suggested by the LIDAR image near to the subject site likely originated in the ancient past, possibly during the lowering of lake levels at the conclusion of the Vashon Stade of the Fraser Glaciation. Geology/Ground Water The published geologic and soils literature reviewed during this phase of our study includes the following: • Geologic Map of King County, Washington, by Derek B. Booth, Kathy A. Troost, and Aaron P. Wisher (2006). • “Geotechnical Engineering Study – Rhododendron Ridge”, Earth Solutions NW, LLC (Earth Solutions), January 29, 2015. • “Preliminary Subsurface Findings” memorandum, Associated Earth Sciences, Inc. (AESI), August 6, 2015. According to published geologic map and literature of the area, the site is underlain by Vashon lodgement till (Qvt). The Qvt was deposited directly from basal, debris-laden glacial ice during the Vashon Stade of the Fraser Glaciation approximately 12,500 to 15,000 years ago. The high relative density of the unweathered till is due to its consolidation by the massive weight of the glacial ice from which it was deposited. This very dense material is generally considered suitable for support of light to heavily loaded foundations when in an intact, undisturbed condition. Exposures of pre-Fraser sediments (Qpf) are mapped at the downslope, western portion of the SE 80th Street right-of-way. The 2015 Earth Solutions report included exploration test pits completed at the subject site. In summary, the Earth Solutions test pits encountered soils described as glacial till at the southern portion of the site, and sandier soils, described as glacial outwash in the report text, at the northern portion of the site. An exploration boring advanced to a depth of 81.5 feet was Rhododendron Ridge Geologic Document Review Newcastle, Washington and Site Reconnaissance May 26, 2016; Revised June 7, 2016 ASSOCIATE EARTH SCIENCES, INC. JPL/ld – KE160152A3 – Projects\20160152\KE\WP Page 5 observed by AESI at the northwest corner of the site. The exploration boring described in the 2015 AESI memorandum encountered materials similar to that described in the Earth Solutions report to roughly 13 feet, overlying very stiff to hard silt and clay. These silts were interpreted as pre-Vashon glaciomarine silts, possibly of Possession age, similar to the pre-Fraser sediments shown on the referenced geologic map. The silt displayed a few fractures, although the degree of fracturing can be variable. Our review of the above-mentioned documents suggests that ground water seepage across much of the site is anticipated to be limited to interflow. Interflow occurs when surface water percolates down through the surficial weathered or higher-permeability sediments and becomes perched atop underlying, lower-permeability sediments. The site is located near the southern extent of the mapped Seattle Fault Zone. Recent studies by the USGS (USGS; e.g., Johnson et al., 1994, Origin and Evolution of the Seattle Fault and Seattle Basin, Washington, Geology, v. 22, pp. 71-74; and Johnson et al., 1999, Active Tectonics of the Seattle Fault and Central Puget Sound Washington - Implications for Earthquake Hazards, Geological Society of America Bulletin, July 1999, v. 111, n. 7, pp. 1042-1053) have provided evidence of surficial ground rupture along a northern splay of the Seattle Fault. The recognition of this fault splay is relatively new, and data pertaining to it are limited, with the studies still ongoing. According to the USGS studies, the latest movement of this fault was about 1,100 years ago when about 20 feet of surficial displacement took place. This displacement can presently be seen in the form of raised, wave-cut beach terraces along Alki Point in West Seattle and Restoration Point at the south end of Bainbridge Island. The recurrence interval of movement along this fault system is still unknown, although it is hypothesized to be in excess of several thousand years. Due to the suspected long recurrence interval, the potential for surficial ground rupture along the Seattle Fault Zone is considered to be low during the expected life of the proposed structures. RESULTS OF SITE RECONNAISSANCE An AESI engineering geologist performed a reconnaissance of the site on May 3, 2016. The purpose of our reconnaissance visit was to provide a visual evaluation of the site conditions, including topography, drainage, geology, hydrology, and vegetation. Our observations of the site conditions during our site reconnaissance are in general agreement with site conditions summarized from our literature research presented above. Site topography varies from low relief in the area of the existing house on the subject site to moderately sloping, with limited areas of steeply (greater than 40 percent) sloping ground, in the areas of the SE 80th Street right-of-way and the property to the west of the subject site. Topographic relief along the portion of the SE 80th Street right-of-way from the subject site to 110th Avenue NE is about Rhododendron Ridge Geologic Document Review Newcastle, Washington and Site Reconnaissance May 26, 2016; Revised June 7, 2016 ASSOCIATE EARTH SCIENCES, INC. JPL/ld – KE160152A3 – Projects\20160152\KE\WP Page 6 160 feet, sloping down to the west. The area of the site surrounding the existing residence is vegetated with landscaping shrubbery, including many rhododendrons, and small- to medium-sized trees, and large (up to 42 inches in diameter) evergreen trees. The sloping area to the west of the subject site is vegetated with abundant ferns, brush, and mixed deciduous and evergreen trees up to 3 feet in diameter. The size and nature of these trees suggests that the slope has been in its current configuration for some time. A series of manhole covers were observed at the ground surface along the SE 80th Street right-of-way, suggesting that utility installation activities have previously been completed down this slope. No ground water seepage was observed on the slope at the time of our site visit. CONCLUSIONS AND RECOMMENDATIONS The sloping area present to the west of the subject site and the SE 80th Street right-of-way do not show evidence of recent deep-seated landsliding. In our opinion, the slope should not be adversely affected by the proposed improvements, including the proposed surface-mounted HDPE storm water pipe leading down the SE 80th Street right-of-way, using current engineering, architectural, and planning standards. Based on review of available published geologic information, it appears that site soils should be suitable to support the anticipated HDPE storm water pipe. In addition, the proposed storm water detention and discharge system will in effect remove a portion of storm water volume from an area above the top of the sloping ground, reducing the risk of saturation of the slope due to runoff from upgradient locations during or subsequent to significant rainfall events. It is our opinion that the risk of landslides or slope erosion posed by the proposed improvements is low for the site provided current engineering standards and the recommendations contained this letter are followed. The steep slopes at the area of the site were predominantly vegetated with ferns, other brush and trees. This vegetation serves to protect the face of the slopes from soil erosion. We recommend that this vegetation remain in place to provide root support for the near-surface soils along the slopes. Storm water runoff from impermeable surfaces should be collected, routed, and discharged through a properly designed storm water system. Uncontrolled discharge from the impermeable surfaces should not be allowed to flow towards or onto the steep slopes. 520 5 0 048 04 6 044 04204003 8 0 34032030028026020018016012010080605 4 0 36040200-20-40-601201008060402402201406 0 5604403403 2 0320 12040BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITSEFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION LIDAR BAS ED TOPOGRA PHYLANDSLIDE SCARPS Document Path: G:\GIS_Projects\aaYear2016\160152 Rhododendron Ridge\mxd\160152_RR_LandslideScarps11x17_NTRPvert.mxd±LEGEND: SITE LANDSLIDE SCARP CONTOUR 5 FT CONTOUR 20 FT STREET PROJ NO. DATE: FIGURE:1 DATA SOURCES / REFERENCES:LIDAR ACQUIRED BY PSLC. GRID CELL SIZE IS 6'.WA STATE PLANE NORTH COORDINATE SYSTEM.NAD83(1991 HARN). ELEVATION UNITS IN US SURVEY FEET.KING CO: STREETS, WATER, PARCELS LOCATIONS AND DISTANCES SHOWN ARE APPROXIM ATE Kits apCounty Pi erc eCounty KingCounty 0 500250 FE ET 5/16KE160152A RHOD ODENDRON RIDGENEWCASTLE, WAS HIN GTON December 28, 2016 AOA-5136 Jill Routt Goldsmith Land Development Services 1215 – 114th Ave. SE Bellevue, WA 98004 SUBJECT: Standard Stream Study for Rhododendron Ridge Storm Extension City of Renton, WA File No. PRE 16-000137 Dear Jill: 1.0 INTRODUCTION This report is the result of a wetland and stream reconnaissance conducted along the route of a proposed storm line from the Rhododendron Ridge Short Plat located at 11230 SE 80th Street within the City of Newcastle. This storm line would be constructed within the SE 80th right-of-way and would direct treated stormwater runoff from the subdivision to a public stormwater system owned by the City of Renton located within the right-of-way of Lincoln Avenue NE. 2.0 GENERAL PROPERTY DESCRIPTION AND LAND USE The SE 80th Street right-of-way in the vicinity of the proposed storm extension is currently unimproved except for a sanitary sewer line that traverses the entire right- of-way. The right-of-way slopes moderately to steeply down from east to west and consists of mixed upland forest interspersed with areas of mowed lawn. 3.0 METHODOLOGY Prior to conducting the site reconnaissance the following mapping systems were reviewed:  Washington Department of Fish and Wildlife’s Salmonscape  Washington Department of Natural Resources’ FPARS mapping  Washington Department of Fish and Wildlife’s Priority Habitats and Species Mapping  City of Renton critical area mapping  King County iMAP Jill Routt December 28, 2016 Page 2 On May 25, 2016 I conducted a wetland and stream reconnaissance on the subject property utilizing the methodology outlined in the May 2010 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0). 4.0 RESULTS None of the critical area maps reviewed indicated any wetlands or streams located on the subject property. The City of Renton critical area mapping does indicate a Type F stream and wetland located off-site to the south. At the time of the field investigation, the site consisted mostly of a mixed upland forest that slopes moderately to steeply down from east to west. Vegetation included a canopy of big-leaf maple (Acer macrophyllum), black cottonwood (Populus trichocarpa), Douglas fir (Pseudotsuga menziesii, western red cedar (Thuja plicata), and red alder (Alnus rubra). Commonly observed understory and groundcover species included hazelnut (Corylus cornuta), salal (Gaultheria shallon), tall Oregongrape (Mahonia aquifolium), Himalayan blackberry (Rubus armeniacus), sword fern (Polystichum munitum), bracken fern (Pteridium aquilinum), English ivy (Hedera helix), Indian plum (Oemleria cerasiformis), snowberry (Symphoricarpos albus), and trailing blackberry (Rubus ursinus). The southwestern portion of the site consisted of a mowed and maintained lawn associated with the off-site residence to the south. In addition, a mowed corridor of grasses extends up the slope within the right-of-way adjacent the existing sanitary sewer line. No hydrophytic plant communities were observed on or immediately adjacent to the site during the reconnaissance. Borings taken throughout and adjacent the undisturbed portions of the site revealed high chroma, non-hydric soils and there was no evidence of ponding or prolonged soil saturation. Soils within the immediate vicinity of the sanitary sewer line were highly disturbed and likely consist of relic back-fill placed during historic installation of the sewer line. 4.1 Off-site Stream One stream was observed off-site to the southwest. The stream within the closest proximity to the site is located within a ditched channel along the north side of the driveway to the existing residence at 4348 Lincoln Ave. NE. Runoff within the stream enters a non-fish passable concrete culvert under Lincoln Ave NE. Although the stream does not currently appear to support salmonids, it is my understanding that the City of Renton has classified this stream as a Type F channel due to the streams potential for fish use. Type F streams require a standard 115-foot buffer per RMC 4-3-050.G.2. This buffer extends into the southwest portion of the SE 80th Street right-of-way. Jill Routt December 28, 2016 Page 3 4.2 Mapped Off-site Wetland The potential off-site wetland to the south as mapped on the City mapping system was not observed and appears to be mis-mapped. This mis-mapping is consistent with a wetland and stream reconnaissance I recently conducted on Parcel 334570-0020 located further off-site in which the same mapped stream was observed but there was no large wetland system on the parcel as depicted on the City mapping. 5.0 HABITAT ASSESSMENT The Washington Department of Fish and Wildlife’s Priority Habitats and Species (PHS) database does not indicate the presence of any threatened, endangered, sensitive, monitored, or priority habitats or species on or adjacent to the property. While the site does likely provide habitat for a variety of wildlife species typically found within suburban environments, no threatened, endangered, sensitive, monitored, or priority species were identified on or adjacent to the site during the field investigations. As defined in RMC 4-11-030.C, Critical Habitat is an area associated with threatened, endangered, sensitive, monitored, or priority species of plants or wildlife and which, if altered, could reduce the likelihood that the species would maintain and reproduce over the long term. Since no critical habitat has been identified on the site, no Habitat Data Report is required. 6.0 PROPOSED PROJECT IPACTS The proposed storm line has been designed to avoid all direct impacts to critical areas. To further minimize impacts to wildlife and significant vegetation, the pipe would be installed within the existing maintained areas. Although crossing the buffer from the off-site stream in the southwestern corner of the property is unavoidable, the storm line would be installed within the mowed lawn portion of the right-of-way and would therefore not require the removal of any significant buffer vegetation (Figure 1). All of the temporary disturbance within the buffer will be fully restored by seeding with native grass following installation of the storm line. Jill Routt December 28, 2016 Page 4 If you have any questions, please give me a call. Sincerely, ALTMANN OLIVER ASSOCIATES, LLC John Altmann Ecologist 1512335 SF SSSSSSSSSSSSXX SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSW SDSDSDWWWW W EEOHU OHU OHU OHU OHU SD SD W SDS S S S S S W W W DS X XXXXX X X XXXXXXWWWWWWWW 30' ROW1512335 SF SSSSSSSSSSSSXX SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSW SDSDSDWWWW W EEOHU OHU OHU OHU OHU SD SD W SDS S S S S S W W W DS X XXXXX X X XXXXXXWWWWWWWW 50352 50358 5035950360503615036650367503685036950370503715037350379503805038450404PROJECT DRAWNDATESCALEREVISEDLandscapeArchitectureAOAEnvironmentalPlanning &Office (425) 333-4535PO Box 578Carnation, WA 98014Fax (425) 333-4509Altmann Oliver Associates, LLC5136-MIT-12-14-16.dwg Rhod od end ro n Rid ge Storm Exte nsio n Source s: Esri, HERE, De Lo rme , Int erma p, in crement P Corp., GEB CO ,US GS, FA O, NPS, NRCA N, Ge oB ase , I GN, K adaste r NL, Ordn an ce Survey,Esri Ja pa n, ME TI , Esri China (Hong Ko ng ), swisst opo , Map myI ndia , ©Ope nSt re etM ap co ntributors, and the GI S User Co mmun ityWDFW All Salmo nScap e Species De ce mbe r 28, 20 16 0 0.1 5 0.30.075 mi 0 0.2 0.40.1 km 1:9,02 8 12/28/2016 Forest Practices Application Mapping Tool (FPAMT) https://fortress.wa.gov/dnr/protectiongis/fpamt/1/1 DNR Home (http://www.dnr.wa.gov/)FPARS Home (http://www.dnr.wa.gov/programs­and­services/forest­practices/forest­practices­application­review­system­fpars)Practices (http://www.dnr.wa.gov/programs­and­services/forest­practices)FP Rules (http://www.dnr.wa.gov/about/boards­and­councils/forest­practices­board/forest­practices­rules­and­board­manual­guidelines)FP Manual (http://www.dnr.wa.gov/about/boards­and­councils/forest­practices­board/rules­and­guidelines/forest­practices­board­manual)Township     1:18,056 Esri, HERE, DeLorme, NGA, USGS, NPS +– 0 0.1 0.2mi   Map Themes Activity Map Townships  Section Survey Lines  Map Registration Tics  Water Type Break  Roads  Trails and Railroads  Watershed Analysis  Search for Layers  Data Active (17)Legend WDFW Test Map Sou rces: E sri, HE RE , DeL orme, USG S, I nterm ap , INCREMENT P, NRCan ,Esri Japan, ME TI, E sri Ch ina (Hong K on g), E sri K orea, Esri (Thaila nd), PH S Re po rt C lip Ar ea PT LN PO LY AS MAPPED SECTION QTR -TW P TO WN SH IP De ce mbe r 28 , 20 16 0 0.3 0.60.15 mi 0 0.55 1.10.275 km 1:19,8 42 SITE King C ou n ty Rho dodendr on Rid ge Sto rm Exte n sion Date: 1 2 /2 8 /2 016 Notes: ±Th e infor matio n in clu de d on t his map has been comp ile d b y Kin g Count y staf f from a variety of source s an d is su bject to cha ng ewithout n otice. Kin g Co unt y makes no re present ations o r wa rra nties, exp re ss o r im plied , a s to accu ra cy, complet en ess, t ime lin ess,or rig hts to the use of such informa tion . This d ocu me nt is not intended for u se as a survey pr od uct. King Cou nty shall n ot be lia blefor a ny g en er al, sp ecial, indirect, incide ntal, o r conse qu en tial damag es including , but not limited to , lost revenu es or lo st profitsresulting from th e use or m isu se of t he info rmat ion cont aine d on this map . An y sale of this map or in formation o n t his map isprohibited except by written p er mission of King County. 2,257 188 City of Renton Print map Template This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. None 4/22/2016 Legend 128064 THIS MAP IS NOT TO BE USED FOR NAVIGATION Feet Notes 128 WGS_1984_Web_Mercator_Auxiliary_Sphere Information Technology - GIS RentonMapSupport@Rentonwa.gov City and County Boundary Other City of Renton Addresses Parcels Environment Designations Natural Shoreline High Intensity Shoreline Isolated High Intensity Shoreline Residential Urban Conservancy Jurisdictions Streams (Classified) Type S Type F Type Np Type Ns Wetlands