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Home My WebLink AboutSWP272186(1) S v R D E S I G N C 0 M P A N Y Drainage Report for the Renton Technical College Building "A" Addition and Walkway Enclosure Renton, Washington 2.4C:;' Ssf�NAIG EXPIRES 7 SvR Design Company 911 Western Avenue, #302 Seattle, WA 98104 CfrY OF RENTON November 4, 1994 R E c h I v E D SvR Project No. 94036 NOV 3 0 ,w;4 j z BUILDING DIVISION! S v R D E S I G N C 0 M P A N Y Table of Contents Page No. A. Technical Information Report Worksheet . . . . . . . . . . . . 2 B. Project Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 1 C. Drainage Features . . . . . . . . . . . . . . . . . . . . . . . . . 1 D. Core and Special Requirements . . . . . . . . . . . . . . . . . 1 E. Detention Requirements . . . . . . . . . . . . . . . . . . . . . . 4 F. Biofiltration Requirements . . . . . . . . . . . . . . . . . . . . . 4 G. Wetpond Requirements . . . . . . . . . . . . . . . . . . . . . . 4 H./I. Conveyance System Analysis . . . . . . . . . . . . . . . . . . . 4 J. Level 1 Off-site Analysis . . . . . . . . . . . . . . . . . . . . . 4 S v R D E S I G N C 0 M P A N Y A. Technical Information Report (TIR) Worksheet P. 1 See attached worksheet, page 2. B. Project Overview Renton Technical College is located at the northwest corner of N.E. 4th Street and Monroe Avenue N.E. The existing Building "A" is located at the south end of the 30- acre campus. This project proposed to construct a 6,600 sf building addition abutting the north end of Building "A". The addition includes welding shops and covered storage areas. Portions of the existing Building A will be renovated and a fire sprinkler system added. Approximately 13 parking stalls will be provided along the north side of the addition. Existing asphalt pavement will be removed and replaced around the perimeter of the building as required to construct the building and related utilities. The site of the proposed addition originally contained portable classroom buildings. The site was recently cleared however, and is currently a flat, grassed area. An extruded concrete curb and sections of broken curb surround the perimeter of the site. C. Drainage Features Surface water from the site currently drains overland to two catch basins lying along the west side of the existing site. Based on record drawings, the basins appear to connect to a storm line that extends from north to south, along the west side of the existing building A. This line ultimately discharges into a pipe storm system located in N.E. 4th Street. No significant changes to the existing storm drain system are proposed. The existing system will be utilized to collect and remove water from the site. The two existing catch basins will be replaced in their current locations with new Type 1 catch basins. These basins are slightly larger and will allow for the top elevation to be set to surrounding paved areas. Downspouts from the new addition and the existing building will be connected directly into the catch basins. New paved areas will be graded to drain to the basins as shown on the plans. D. Core and Special Requirements Core Requirements: (1) Discharge at the Natural Location Proposed site discharge point remains the same as current discharge point, into an enclosed storm system. (2) Off-Site Analysis See Section J below. RTC Building "A" Addition November 4, 1994 z Page 4-of-2- King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PART I PROJECT OWNER AND PART 2 PROJECT LOCATION AND DESCRIPTION PROJECT ENGINEER Project Owner 415A O I re-4,I41/CAA- Project Name Address 0c,00 A/,5- 114'' S . Location Phone 235- ?/��0 3 ✓on �oeya Township 23 N Project Engineer /LI4L)CAWN ,E'Wou!w Range 5E Svc D�541V Co. Section 9 Company Project Size AC Address Phone 5ewrrL� Upstream Drainage Basin Size AC Z -032 69 PARr3TYPEOFPERMrrAPPUCATION., . �- • �- 0 Subdivision DOF/G HPA Shoreline Management �l Short Subdivision COE 404 Rockery Grading 0 DOE Dam Safety 0 Structural Vaults Commercial FEMA Floodplain 0 Other 0 Other 0 COE Wetlands 0 HPA /IovE • . - SIk Community L-/T y Or- relY rrV Drainage Basin L'G'v'/ER River 0 Floodplain l—J Stream Wetlands Critical Stream Reach Seeps/Springs Depress io ns/Swales High Groundwater Table u Lake i_!I Groundwater Recharge Steep Slopes Other 14,62,1YFre Lakeside/Erosion Hazard Soil Tye Slopes Erosion Potential Erosive Velocities Additional Sheets Attatched 1/90 S v R D E S I G N C 0 M P A N Y (3) Runoff Control p. 3 See Section E below. (4) Conveyance System See Section H below. (S) Erosion/Sedimentation Control Erosion and sediment control plan and notes are shown on the drawings. (6) Maintenance and Operation Maintenance and operation of the drainage facilities is the responsibility of the Renton Technical College. (7) Bonds and Liability King County Code bonding and liability requirements do not apply. Special Requirements: (1) Critical Drainage Area Project does not lie within a Critical Drainage Area. (2) Compliance with an Existing Master Drainage Plan Project does not lie within a Master Drainage Plan area. (3) Conditions Requiring a Master Drainage Plan The project does not require a Master Drainage Plan. (4) Adopted Basin or Community Plans Project lies within the Cedar River Basin Plan, and within the Newcastle Community Planning Area. (S) Special Water Quality Controls The proposed development within this basin will decrease the net vehicular area. No special water quality controls are required. (6) Coalescing Plate Oil/Water Separators The proposed development is less than five acres. No coalescing plate oil/water separators are required. (7) Closed Depressions The proposed project does not lie within a closed depression. (8) Use of Lakes, Wetlands or Closed Depressions for Peak Runoff Rate Control This project does not propose to use a lake, wetland or closed depression for peak runoff control. RTC Building "A" Addition November 4, 1994 S v R D E S I G N C 0 M A N Y E. Detention Requirements p. 4 See pages 6 and 7 for plans showing the predeveloped and developed site coverages. A summary of the site land coverages are as follows: Predeveloped site (with portables) Developed site Net chanze Pervious (landscape) area 3576 1525 -2051 sf Impervious (vehicular) area 4245 5712 +1467 sf Impervious (non-vehicular) area 7329 7913 + 584 sf TOTAL 15,150 sf 15,150 sf 0 sf Since the total increase in new impervious surface is less than 5,000 sf, the site is exempt from detention requirements. F. Biofiltration Requirements Proposed project has 1,467 sf of new impervious area that is subject to vehicular traffic. Since this area is less than 5,000 sf, no biofiltration is required. G. Wetpond Requirements Proposed project has less than 1 acre of new paved impervious area (subject to vehicular traffic) and therefore no wetpond is required. H./I. Conveyance System Analysis Conveyance system capacity and velocity analyses are enclosed on pages 8 and 9. The proposed project storm lines will connect into the existing storm drainage system at the current site connection point of two catch basins. No indication of capacity problems were observed at these points. J. Level 1 Off-site Analysis A field visit of the site and downstream system was made by the project engineer on October 27, 1994. The existing on-site storm drainage from the proposed project site drains overland to two catch basins lying along the west side of the existing site. Roof drains from the existing building are tightlined to the most southerly of the catch basins. Based on record drawings, the basins appear to connect to a storm line that extends approximately 300 if from north to south, along the west side of the existing building A. Field surveys indicate RTC Building "A" Addition November 4, 1994 S v R D E S I G N C 0 M P A N Y p. 5 this line is at approximately a 1.3% slope. The pipe turns westward at a manhole located off the southwest corner of Building A. The pipe extends westward approximately 240 feet to another manhole. The line then turns south and extends 80 if connecting to a manhole in N.E. 4th Street. No indication of capacity problems was observed. The two existing site catch basins are full of sediment to near the outlet elevation. These will be replaced as indicated above. RTC Building "A" Addition November 4, 1994 Dirt Parking lot L /// Speed i Speed / Asphalt Bump Roadway i Bum{ i \ y _.._.. . ..,. .-.. ...._.._.._. _ _.._.._..�..La ped Ilk: II �ER� + i I Landsc ' �C� 1 r Asphalt I I-rt i i --x�x i' ER! Temp Steps ;filer w I I 0 yOm I I Tom s I I Pc L, Po t a I e s--� , . } O W I I 1I To be removed Z-2Tamp �� k D I I Steps /ER` ;ERA a sl j MOL \N Asph N " SL1 �, SD' a ? � Pu `� SM Pow I �I X s Q sue, . ram. . ° c I I O Box PCC Walkway �o IC � D I I , I L..J be EXisf. fja �� `I r I I o 14h O/H I Door nip I. I T I I n 1 f. Dirt rw lclny lut M. 7 ri i w X Ir TEES �9 ( ORD " NC�1RU�``BLO�S T� x PARKING —'/ H 10460 �� - 4 00 � � ' x Fno S 52 WATER �� 24 a° ,LF 1C' D.I. CLAS 52 WATER LINE d in �:car Ci \ '" ACKFr..OW ' PROTECTION l� ` r n a Bciler { .�� /n x•X� oaM yI..\�;I DR 7 Ternp DH C 330.54 e 331Asphulr FH WATER � METER -' YmaYi, x, —,ry!x X WALL c; SLAB c4 14 _ mTe p P a s P� nroryM Y6 BUILDING 'A' ADDrMN FIFE. 333.04 n D • r A n CF;,.IONp lOP 0� �I' " 1 ,,� 1 1 „nf x M EXI< . ER BUII M � Pc. o pa . •U - •• -_—_ -_-_ --_i__.____ f v 56 .. r•-, _._.__. _ � c,: Yl � � r� Yi c _ — �r-�'✓T' �1 erg. U� t ra jo EXISTING BUILDING 'A' j Pcc Yy FFE. 333.04 t �c Paid Civil Engineering Sheet v of V R Planning Landscape Architecture Job k Project Designed by D E S I G N C 0 M P A N Y Checked by Date �/�T, Con f��a„-�.� 515 Jeo, r! A55vrne hv�. �G o� �, 2 rntin � ,f'�' Sd✓/c� /y7�c�vrr�� 01 . 7 " Xt- K i Co/�Gc�vh �✓rr-a = /2BD � = D. 02 9� zs IJ r 911 Western Avenue • Suite 302• Seattle,WA 98104 •Phone 206.223 0326 t(� 'I D Civil Engineering Sheet [_of J 11 n Planning Job k Landscape Architecture Project Designed by Date D E S I G N C 0 M P A N Y Checked by Date Vel � 2 911 Western Avenue • Suite 302• Seattle.WA 98104 • Phone 206.223 0326