1420 80TH ST SW BASE FILE 2018-01-02 MF Import

INTRODUCTION: EVERETT 526 PROPERTY 15 A 5.8 ACRE RECTANGULARLY SHAPED SITE LOCATED BETWEEN STATE. ROUTE 516 AND 80TH STREET SOUTHWEST APPROXIMATELY 550 FEET WEST OF 16TH AVENUE WEST. THE PROPOSED DEVELOPMENT WOULD INCLUDE TWO OFFICE/WAREHOUSE BUILDINGS WITH A TOTAL ROOF AREA OF APPROXIMATELY 95,386 SQUARE FEET. OFFICE FRONTAGE. FOR THE NORTH BUILDING WILL BE TOWARD SR 516 AND THE SOUTH BUILDING TOWARD BOTH STREET. SITE ACCESS WILL BE FROM BOTH STREET WITH DRIVEWAYS ALONG THE EAST AND WEST PROPERTY LINE. THE AREA BETWEEN THE TWO BUILDINGS WILT. BE UTILIZED FOR TRUCK LOADING AND UNLOADING. STORM WATER RUNOFF FROM THE IMPERVIOUS SURFACES WILL BE DETAINED AND RELEASED AT THE PRE -DEVELOPED RUNOFF RATE. STORM WATER DETENTION WILL BE PROVIDED USING 3 SEPARATE SYSTEMS. ONE LOCATED BETWEEN THE BUILDINGS UTILIZING SU'tFACE PONDING AND 2 OTHERSWITHIN THE SOUTH PARKING LOT UTILIZING UNDERGROUND STORAGE PIPE. THE ALLOWABLE RELEASE RATE AND REQUIRED STORAGE VOLUME WILL BE DETERMINED PEA THE CITY OF EVERETT. PRIOR TO DISCHARGE FROM THE SITE ALL PKG. .Cor . RUNOFF WILL BE CONVEYED THROUGH BIOFILTRATION SWALES. STORM WATER RUNOFF FROM THE AREAS NORTH OF BUILDING "A" WILL BE CONVEYED TO A 100 FOOT LONG BIOFILTRATION SWALE LOCATED ALONG THE WESTERN PROPERTY LINE.. THE 225 FOOT LONG BIOFILTRATION SWALE ALONG THE SOUTH PROPERTY LINE WILL RECEIVE. RUNOFF F.ON ALL IMPERVIOUS SURFACES WITHIN THE SITE (TRIBUTARY AREA - 4.. ACRES). BOTH SWALES WILL BE CONSTRUCTED WITH A 10 FOnT WIDE BOTTOM AND 3:1 (H:V) SIDE SLOPES. THE CALCULATED DEPTH OF FLOW FOR THE 25 YEAP STORM IS LESS THAN THE 5.4 INCH MAXIMUM. SPECIFIED BY THE CITY. THE CALCULATED 25 YEAR VELOCITY FOR THE SOUTHEFN SWALE IS 1.16 FPS WHICH IS LESS THAN THE. 4 FPS MAXIMUM. AN OIL WATER SEPARATOR VAULT WILL BE LOCATED DOWNSTREAM FROM THE CONTROL STRUCTURE. THE CONTROL STRUCTURE WILL HAVE A TURN DOWN 90 DEGREE BEND WITH A ORIFICE OUTLET DISCHARGING TO THE VAULT. THE ORIFICE HAS BEEN SIZED TO DISCHARGE AT THE. ALLOWABLE RATE (AS DETERMINED BY SECTIONS 4, 3, 16, 2) WHEN THE SYSTEM IS AT MAXIMUM HEAD. A RISER STRUCTURE WITH A MULTIPLE ORIFICE WILL DISCIIARGE TO CATCH BASIN NO. 19. THE. ORIFICE FOR THE RISER WILL BE SIZED TO DISCHARGE AT THE ALLOWABLE SITE RATE LESS THE FLOW RATE TO THE VAULT. TFMPORARY EROSION AND SEDIMENTATION CONTROL. PONDS WILL BE CONSTRUCTED AT THE NORTHWEST AND SOUTHWEST CORNERS OF THE SITE. INTERCEPTOR SWALES WILL CONVEY THE SILT LADEN STORM WATER RUNOFF TO THE PONDS. THE REQUIRED POND VOLUME HAS BEEN CALCULATED USING IOU CUBIC FEET/ACRE ASSUMING THE ENTIRE. SITE IS GRADED AT ONE TIME.