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Home My WebLink About22-102749-UP-Level One Downstream Storm Analysis-06-15-2022-V1 LEVEL ONE DOWNSTREAM STORM DRAINAGE ANALYSIS FOR PLANT 2 RELOCATION JUNE 9, 2022 LEVEL ONE DOWNSTREAM STORM DRAINAGE ANALYSIS FOR PLANT 2 RELOCATION A portion of the Southeast Quarter of the Southeast Quarter of Section 20, Township 21 North, Range 4 East, of the Willamette Meridian, City of Federal Way, Washington Prepared for: Prepared by: 35000 Pacific Hwy South LLC Apex Engineering LLC PO Box 94176 2601 South 35th Street, Suite 200 Seattle, WA 98124-6476 Tacoma, Washington 98409 (253) 473-4494 File #35072 June 9, 2022 Project Engineer: Gabe L. Jellison, P.E. 1 LEVEL ONE DOWNSTREAM STORM DRAINAGE ANALYSIS Task 1. Study Area Definition and Maps Federal Way as-built/record drawings and GIS maps were obtained for the off-site areas and are referenced for the downstream drainage path . The site discharges to a catch basin within Pacific Highway South to the west, which conveys the drainage to the south where it discharges to a City regional storm facility located approximately one-quarter mile downstream. These facilities discharge to Hylebos Creek where drainage would flow generally to the south to a point one mile downstream. Refer to the Downstream Drainage Path map and associated documentation in this section for additional information. The Federal Way Crossings commercial development is located upstream of the project site and has separate stormwater facilities. Run-on from adjacent properties is assumed to be negligible. Task 2. Resource Review The project site is located within the Hylebos Creek and Lower Puget Sound Basin Plan area. The requirements of the Basin Plan should not be more restrictive than the requirements of the KCSMDM and COFA. The project is not located within a known floodplain and/or floodway per FEMA mapping. Refer to the FEMA FIRM included as Figure 3.2. There are no other known offsite analysis reports within the same subbasin. There are no known erosion hazard or landslide hazard areas located on the project site or within one mile downstream of the site per City of Federal Way critical area mapping. There are no known wetlands on the project site, but the Hylebos wetland and creek is located approximately one-half mile downstream of the site. Refer to Figure 3.3 for the City of Federal Way Critical Areas Map. Per King County GIS, there are no listed drainage complaints within one mile downstream of the project site. One drainage complaint is listed for a parcel south of the project site that is not within the downstream drainage path . The complaint was for a water quality audit inspection and was closed in June 2013. Refer to Figure 3.4 for further information. There are no known road drainage problems within one mile downstream of the project site. 2 NRCS’ web soil survey information was referenced for the soil mapping of the site. The site consists of Everett-Alderwood gravelly sandy loams for the northern portion of the site and Urban land for the southern portion of the site per the mapping. Per King County GIS, there are no channel migration hazard areas within one mile downstream of the project site. The Washington State Department of Ecology’s (ECY) published Clean Water Act Section 303d list of polluted waters has identified an unnamed water body in the area of the project site as a Category 5 water due to temperature and dissolved oxygen. The water body is listed as unmappable and it is unclear from the available information if the project site drains to this water body. Additionally, Hylebos Creek greater than a mile downstream of the project is identified as a Category 5 water due to temperature, dissolved oxygen, and bacteria. No additional requirements from these assessments have been identified at this time. Refer to Figure 3.5 for reports of the assessed water quality areas. There are no known designated water quality problems, and no additional requirements from adopted stormwater compliance plans downstream of the project site have been identified at this time. Task 3. Field Inspection A Level 1 field inspection was performed on February 11, 2022. The weather was overcast and approximately 45 degrees. The drainage path to a point more than one- quarter mile downstream was observed. Refer to the Downstream Drainage Path Map and associated Drainage System Table in this section for additional information. From the field inspection, it was determined that run-on from adjacent properties can be considered negligible. The Federal Way Crossings commercial development is located upstream of the project site on the north and east sides and has separate stormwater facilities that will collect runoff. Pacific Highway South to the west and South 351st Street to the south is located downgrade of the project site. Task 4. Drainage System Description and Problem Descriptions The majority of the project site is proposing infiltration for water quantity control. The western portion of the 351st Street improvements is unable to gravity flow to the onsite storm facilities and will discharge to the existing conveyance system within Pacific Highway South, which is the current discharge location for the existing site. The field inspection was aided by King County GIS information and City of Federal Way record drawings. Runoff from the site discharges to a catch basin within the 3 easternmost Pacific Highway South/State Route 99 (SR99) northbound travel lane. Runoff would then continue generally south within 36-inch pipes for approximately 253 feet. Runoff would then continue generally south within 48-inch pipes for approximately 354 feet to a catch basin within the eastern sidewalk of SR99. Runoff would then continue generally east within a 48-inch pipe for approximately 173 feet to a flow splitter for a City regional stormwater facility. Runoff would then continue generally south within 48-inch and 60-inch pipes for approximately 39 feet where it enters the City regional stormwater facility. Runoff would continue generally south within the City facility for approximately 650 feet to a point more than one-quarter mile downstream. Refer to the Downstream Drainage Path Map and associated Drainage System Table in this section for additional information. Task 5. Mitigation of Existing or Potential Problems No existing or potential problems within a mile downstream have been identified at this time. 4 FIGURE 3.1 – DOWNSTREAM ANALYSIS Hylebos Creek -- 45 degrees, overcast 9:30 AM 2/11/2022BasinSubbasin Name Subbasin Number Weather ConditionsDateDrainage Component Type, Name, and SizeDrainage Component Description Slope Existing Problems Potential Problems Observations of field inspector, resource reviewer, or residentType: sheet flow, swale, stream, channel, pipe, pond; Size: diameter, surface areaDrainage basin, vegetation, cover, depth, type of sensitive area, volume+/-, %Tributary area, likelihood of problem, overflow pathways, potential impactsCatchbasinExisting 10' +/- deep cb(1)(2)None observed Sedimentation Impacts not expected1 - 2 36-inch pipe0.70(1)0 - 29 None observed Under capacity Impacts not expectedCatchbasinExisting 10' +/- deep cb(1)(2)None observed Sedimentation Impacts not expected2 - 3 36-inch pipe0.64(1)29 - 203 None observed Under capacity Impacts not expectedStorm ManholeExisting 7' +/- deep sdmh(1)(2)None observed Sedimentation Impacts not expected3 - 4 36-inch pipe0.60(1)203 - 253 None observed Under capacity Impacts not expectedCatchbasinExisting 11' +/- deep cb(1)(2)None observed Sedimentation Impacts not expected4 - 5 48-inch pipe1.66(1)253 - 494 None observed Under capacity Impacts not expectedCatchbasin Existing 11' +/- deep cbNone observed Sedimentation Impacts not expected5 - 6 48-inch pipe1.15(1)494 - 607 None observed Under capacity Impacts not expectedCatchbasin Existing 12' +/- deep cbNone observed Sedimentation Impacts not expected6 - 7 48-inch pipe0.81(1)607 - 780 None observed Under capacity Impacts not expected7 Diversion ManholeExisting 10' +/- deep cb - Flow splitter prior to regional storm facility(1)(3)None observed Sedimentation Impacts not expected7 - 8 60-inch pipe4.62(1)780 - 793 None observed Under capacity Impacts not expected8 CatchbasinExisting 17' +/- deep cb(1)(3)None observed Sedimentation Impacts not expected8 - 9 48-inch pipe0.92(1)793 - 819 None observed Under capacity Impacts not expectedPond InletInlet to existing City of Federal Way regional storm facility(1)(3)None observed Erosion/scouring Impacts not expected9 - 10 Regional pondExisting City of Federal Way regional storm facilityN/A 819 - 1469 None observed Under capacity Impacts not expectedPond outlet structureControl structure for existing City of Federal Way regional storm facility(1)(3)None observed Sedimentation Impacts not expected10 - 11 48-inch pipe0.20(1)1469 - 1520 None observed Under capacity Impacts not expectedCatchbasinExisting 5' +/- deep cb with debris cage top(1)(3)None observed Sedimentation Impacts not expected11 - 12 48-inch pipe0.37(1)1520 - 1574 None observed Under capacity Impacts not expectedCatchbasinExisting 7.5' +/- deep cb(1)(3)None observed Sedimentation Impacts not expected12 - 13 48-inch pipe0.37(1)1574 - 1672 None observed Under capacity Impacts not expectedCatchbasin Existing 7.5' +/- deep cbNone observed Sedimentation Impacts not expected13 - 14 48-inch pipe0.46(1)1672 - 1803 None observed Under capacity Impacts not expectedCatchbasin Existing 7.5' +/- deep cbNone observed Sedimentation Impacts not expected14 - 15 48-inch pipe0.37(1)1803 - 1825 None observed Under capacity Impacts not expectedPipe end Outlet to unnamed stream w/ rip rapNone observed Erosion/scouring Impacts not expectedNotes:(1) Slope/inverts per City of Federal Way Record Drawings(2) Unable to access/open structure, located within SR99 travel lane(3) Unable to access/open structure, located within fenced/locked City facility111520121574OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLEKING COUNTY SURFACE WATER DESIGN MANUAL, CORE REQUIREMENT #2Constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision, other erosionPlant 2 Relocation (Job #35072) - Downstream Analysis229SymbolDistance from Site Discharge (+/-, ft)See Map1/4 mi = 1,320 ft1010146932034253549466079819780793131672141803151825 7 FIGURE 3.2 – FEMA FIRM PROJECT SITE 9 FIGURE 3.3 – CRITICAL AREAS MAP Critical Areas!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! ! !!!!!!!!!!!!!!!!!!!!!! ! ! !! ! ! ! ! !! ! ! ! !! ! ! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! SW 312th St SW 320th St Interstate 5 Po r t o f T a c o m a R dMa ri n e Vi e w Dr MarineViewDr Northshore Pkw y Military R d S 28th Av SE n c h a n t e d P kw y Military Rd SPe a s l eyCanyonRdRedondoWySRedondoBeachDrSPacific Hwy SMarineViewDrInterstate 5StarLake R d 1stWySS 324th St E 11th StInterstate5SW Dash Point Rd S W D ashP ointR dNE 49th St10thAvSWSW Campus Dr SWCampus Dr S 336th St Pacific Hwy SSW 330th St SW 356th St NorpointWyNES 356th St Pacific Hwy SS356thSt Hwy 18WeyerhaeuserWySSDashPointRd1st Av SS 304th St Mi l i t ar yRdS S 288th St Military Rd SS 288th St S 272nd St Pacific Hwy S S 312th St I nt er st at e5Military Rd SS 272nd St Pacific Hwy S16th Av SMarineView Dr E n c h a n t e d P kw y MilitaryRd1st Av S9thAvS21st Av SW23rd Av S51st Av S16thAvSHwy 18S 348th St S 308th St PacificHwySMilitaryRdSSW 340th StHoy t R dS W SW 336th St 21st Av SWH oytR d S WSW 320th St SW 308th St SW Dash Point RdSWD ash P oi nt R d 35th Av SW47th Av SW12th Av SW21st Av SW11th Av SW8th Av SWS 3 2 8 thSt5th Av SS 336th St 7th Av6thAv8thAv6th Av SWSW 344th St 28th Av S20th Av SS 373rd St 34th Av SS 298th St 37th Av SS 304th St 31stAvSS 320th St20th Av SS 312th St Pacific Hwy SS 320th St 11th Pl S1st Av S8th Av SPavillionsCenter CelebrationCenter SeaTacVillage Pal-doWorldPlaza The Commons atFederal Way GatewayCenter Twin LakesVillage CampusSquare Federal WayMarketplace Federal WayCrossings LakehavenTreatmentCenter(Redondo) LakehavenTreatmentCenter (Lakota)LakeGroveElem. LakeDolloffElem. LakelandElem ValhallaElem. SilverLakeElem. WildwoodElem. BrigadoonElem. Twin LakesElem. AdelaideElem. SherwoodForestElem. PantherLakeElem. CamelotElem. NautilusElem. Mark TwainElem. Rainier ViewElem. OlympicViewElem.GreenGablesElem. EnterpriseElem. MirrorLakeElem. Star LakeElem. WoodmontElem. IllaheeMiddle School LakotaMiddleSchool SacajaweaMiddle School KiloMiddleSchool SaghalieMiddleSchool SequoyahMiddleSchool PublicAcademy DecaturHigh School Federal WayHigh School ThomasJeffersonHigh School Todd BeamerHigh School TrumanH.S. TotemMiddle School Golf Golf Twin Course Course Lakes NorthshoreGolf Course Star LakePark &Ride Federal Way/S 320th StreetPark & Ride Twin LakesPark &Ride South FederalWay Park &Ride RedondoHeightsPark & Ride TransitCenter Federal WayCommunityCenter SteelLakeAnnex CityHall Dumas BayCentre KnutzenTheatre ParkLakota SacajaweaPark FrenchParkLakePark AdelaidePark CamelotPark Dash PointState Park SaghaliePark LakeGenevaPark GlenNelsonPark WestHylebosWetlandsPark FiveMileLakePark BingamanPond Park B.P.A. TrailB.P.A. TrailWestCampusTrailB.P.A.TrailSteel LakePark CelebrationPark Dumas Bay Sanctuary Park LaurelwoodPark TownSquarePark Brooklake CommunityCenter South CountyBallfields Alderbrook Park Dash PointHighlands Park Spring ValleyOpen Space Fisher'sPond Panther LakeOpen SpacePark PovertyBayOpenSpace Pacific RimBonsai Collection Rhododendron SpeciesBotanical Garden EnchantedPark Pie r c e C o u n t y Kin g C o u n t y Pie r c e C o u n t y King County Pierce County King CountyPierce County Kin g C o u n t y FireStation 73(Kent) FireStation65 FireStation 61 FireStation 64 FireStation 63 TrainingCenter FireStation62 FireStation66 Federal WayRegional Library 320thStreetLibrary Fife Milton Tacoma DesMoines Edgewood Pacific Kent FederalWay FederalWay Hyl e b o s C r e e k W a t e r w a y Bla i r W a t e r w a y P uyallu p R i v erPuget Sound BayDumas PovertyBay Sit c u m W a t e r w a y CommencementBay LakeSteel Star Lake MirrorLake GenevaLake North Lake EasterLake Dolloff LakeLakeFenwi ckTroutLake FiveMileLakeLakeKillarneyLake Lorene JeaneLake !"#$5 !"#$5 509 18 509 509 161 509 509 161 99 99 !"#$5 99 !"#$5 WhiteRiver Mill Creek HylebosCreek LowerPugetSound Lower GreenRiver HylebosCreek LowerPugetSound 5 City of Federal Way Critical Areas Map Map Date: May 2016City of Federal Way,GIS Division33325 8th Ave SFederal Way, WA 98003(253) 835-7000www.cityoffederalway.com ´ This map is accompanied by NO warranties, and is simply a graphic representation.J:\standard\reference\sensitive.mxd KingCounty Vicinity MapHylebos Creek Lower Green River Lower Puget Sound Mill Creek White River Erosion Hazard Area Landslide Hazard Areas Wetlands (1998 City Survey) Lakes Streams Drainage Basins:Critical Areas:Water Features: Legend: Boundaries are approximate. Remember, ADDITIONAL SENSITIVE AREAS MAY EXIST. See Map Notes below for more information.Please Note:Map Notes: Wetlands and streams were identified in a1998 City of Federal Way survey. Data for the Landslide hazard and erosion hazard areas is provided by King County. Drainage basin boundaries within city limits havebeen verified by the City of Federal Way. Basin boundaries outside of city limits are provided by King County and have not been verified by the City of Federal Way. Critical area information is provided forillustrative purposes ONLY. Actual boundaries are subject of field verification. ADDITIONAL CRITICAL AREAS MAY EXIST. Critical areas in Pierce County are not shown. The City of Federal Wayshall not be liable for any damages due to the use or misuse of the information represented on this map. Wetlands are onlyshown in Federal Way and its Potential Annexation Area.Contact the City for an explanation of these areas and theregulations that govern them.Source: City of Federal Way, King County 0 0.5 10.25 Miles Scale: 50 Acres 5 20 47°15'5.46831"N122°25'3.78156"W47°21'46.42899"N 122°25'3.78156"W47°21'46.42899"N 122°16'19.25508"W47°15'5.46831"N 122°16'19.25508"WA B C D E F A B C D E F 1 2 3 4 5 6 7 1 2 3 4 5 6 7 PROJECT SITE 11 FIGURE 3.4 – DRAINAGE COMPLAINTS K in g Date : 3/18/20 22 Notes: ±The informati on included on this map has been c ompil ed by King County s taff from a variety of sources and issubject to change without notice. King County makes no repr esentations or warr anties, ex press or implied,as to accurac y, completeness, timel iness, or rights to the us e of such information. T hi s doc ument i s not intendedfor use as a s urvey product. Ki ng County shall not be l iable for any general , special, indirect, incidental, orconsequential damages i ncl uding, but not li mited to, lost revenues or los t profits resulting from the us e or mi sus eof the information contained on this map. Any sale of thi s map or informati on on this map is prohi bited exc ept bywritten permi ss i on of Ki ng County. King C ou nty iMap PROJECT SITE Figure 3.4: Downstream Drainage Complaints PLANT 2 RELOCATION Apex Job #35072 #Parcel Address Type Problem Date Closed Comments 2013-0132 2021049059 1393 S 351st St WQAL WQAI 6/11/2013 N/A 14 FIGURE 3.5 – ASSESSED WATER QUALITY AREAS Fed Way Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS,FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, EsriJapan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and March 17, 2022 0 0.5 10.25Miles K Assessed Water/SedimentWater Category 5 - 303d Category 4C Category 4B Category 4A Category 2 Category 1 Sediment Category 5 - 303d Category 4C Category 4B Category 4A Category 2 Category 1 PROJECT SITE