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Home My WebLink AboutSWP272255(7) STORM DRAINAGE REPORT FOR RAYMOND AVENUE CENTER RENTON, WASHINGTON BY BUSH, ROED & HITCHINGS 2009 MINOR AVENUE EAST SEATTLE, WA 98102 (206) 323-4144 CONTACT: JOHN E. ANDERSON, P.E. ,��• w TD RH JOB NO. 92233 . 02 �O "0•p 26878 W MARCH 26, 1996 o��s ON,1,E � w AL EXPIRES 12/1/q Raymond Avenue Center is a 10 .39 acre site located at the southwest quadrant of the intersection of Southwest 19th Street and Raymond Avenue South. The proposed development would occur on Parcel B. Development would include the construction of a 99, 900 square foot building and associated parking. Spring Brook Creek defines the southern and western boundary of the site. The original easement for Spring Brook Creek did not coincide with the actual stream location. Bush, Roed & Hitchings has prepared a lot line adjustment which defines the easements according to the surveyed location of the stream. Lot lines shown on the documents submitted for site plan and shoreline review reflect the most current survey information. Several years ago, the site was filled to approximately elevation 18. Fill slopes toe down to the banks of Spring Brook Creek on the southern and western boundary. On the eastern boundary, the fill slopes toe down approximately 60 feet west of the east property line. Areas east of the fill slopes are classified wetlands. A 60 inch culvert discharges into a ditch on the west side of Raymond Avenue. The ditch is located within the 19th Street right-of-way just north of the north property line. Existing drainage maps indicate the area tributary to the ditch include Panther Creek Wetlands. From the 60 inch culvert, the ditch flows west to Spring Brook Creek. Existing grades on the developable areas are approximately 9 to 10 feet higher than surrounding grades . The ground surface where the proposed development will occur is flat. Tall grasses cover the area. There are no significant trees located within the buildable area. Storm water run-off from the site sheet flows to the surrounding low lands . No defined drainage courses were observed on the site. The proposed site plan maintains a minimum 50 foot setback from Spring Brook Creek and a. 25 foot setback from the surrounding wetlands. Storm water run-off from the developed areas will sheet flow to catch basins located in the parking lot. The storm water will then be conveyed directly to a combine wetpond/detention pond facility. A wetpond is required because the development is located next to Spring Brook Creek, and has more than one acre of impervious surface area subject to vehicular traffic. Also, since the storm water will discharge into Spring Brook Creek the detention volume will be calculated using Department of Fisheries guidelines. These standards require a peak discharge rate from the detention system equal to 1/2 the pre-developed 2 year rate for a 10 year developed storm inflow. Peak discharge rates from the detention system for storm events greater than the 10 year match pre-developed peak rates for the same storm event . Analysis of the combined wetpond/detention pond design shows that it performs significantly better than the Department of Fisheries guidelines . Initial sizing was based on maximizing the available area. The goal was to make the detention volume shallow. By making the detention volume shallow, there is not sufficient head pressure to reach the pre-developed 25 year and 100 year peak discharge rates . The calculations show the developed 25 year and 100 year storm will be discharged at approximately 1/2 the pre- developed 10 year peak rate. Therefore, development of this site will reduce the peak rates for all storm events . Volume provided by the wetpond exceeds the required volume by approximately a factor of three. This is also a result of maximizing the available area. The design guidelines require a 3 foot minimum depth plus 1 foot of sediment storage. Maintaining the depth requirement across the pond provides a storage volume of approximately 28, 846 cubic feet. The required volume is approximately 8, 514 cubic feet. Therefore, the storm water quality will be significantly better than required by Department of Fisheries guidelines . The additional wetpond volume will also mitigate the two small areas filled within the 100 year flood plain (below elevation 16) . reports/92233 . 02 I LONGACRES RACE TRACK \ � RFN N T T 0d�d� m r CiFiC M Sm = ^� 0li / \D THOMAS AV O RAYMOND AV S.W. 0 Z D (VALLEY FREEWAY) STATE SIGN ROUTE 167 i a uSLiNOTON g 19� RM333 suuimvvt. ——� RM334 16 ZONE � uwj I W Z � I EET IQ ill i : I � I I ZONE X M I I ZONE ZONE X j X II s-G-7— Now �DD �� )088 16, • BRIDGE UNDER CONSIRUCII(A, ' c c sou-�1�FST 77Tf, RM338 STRFFT Ftu-. I co Yp �loop , CZ4 GF 16.40 BREAK ------------- - IE 14.00 _ I 70 �\ SS MH �• - TE=19.00+ - - - IE=11.26 EXIST. SS MH .04 TSS 11 ` TH A N U E i I TE== CN EX. ' IE10.84 �~ 8' SAN SEWER RAYM AVENUE S c K 1�� ford s L EPP Sam- Ml c mom OWN MCI- OR kill, JLMILW IQr�1. f/�VNaf i� - �. � 1 i o llk at gig MIMW INN • w��►ter:� • S d �1IWE al /,��'�� I� MIR/�t'r!I�_ T KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL —ABLE 3.5.211 SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A B C D Cultivated land(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed or older second growth 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% or more of the area 68 (SD 86 90 fair condition: grass cover on 50% to 75% of the area 77 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 i Impervious surfaces, pavement, roofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 Single Family Residential (2) Dwelling Unit/Gross Acre % Impervious (3) 0 DU/GA t5 Separate curve number 1. DU/GA 20 shall be selected 1. 2. DU/GA 25 5 for pervious and 2.5 DU/GA 30 impervious portion 3.0 DU/GA 34 of the site or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 Planned unit developments, % impervious condominiums, apartments, must be computed commercial business and industrial areas. (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. 3.5.2-3 11/92 i 3/10/96 Bush, Roed & Hitchings, Inc. page 1 Raymond Industrial Center John E. Anderson, P.E. 92233 BASIN SUMMARY BASIN ID: B1 NAME: 2 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5.24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2.00 inches AREA. . : 5. 24 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 30.30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 0.00 Acres CN. . . . . 98. 00 PEAK RATE: 0. 31 cfs VOL: 0.25 Ac-ft TIME: 490 min BASIN ID: B2 NAME: 10 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 .90 inches AREA. . : 5. 24 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 30.30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 0.00 Acres CN. . . . . 98. 00 PEAK RATE: 0.89 cfs VOL: 0.51 Ac-ft TIME: 480 min BASIN ID: B3 NAME: 25 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5.24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 .40 inches AREA. . : 5. 24 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 30. 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 0.00 Acres CN. . . . . 98.00 PEAK RATE: 1.27 cfs VOL: 0.68 Ac-ft TIME: 480 min t 3/10/96 Bush, Roed & Hitchings, Inc. page 2 Raymond Industrial Center John E. Anderson, P.E. 92233 BASIN SUMMARY BASIN ID: B4 NAME: 100 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3.90 inches AREA. . : 5. 24 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 30. 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 0.00 Acres CN. . . . . 98.00 PEAK RATE: 1.68 cfs VOL: 0.86 Ac-ft TIME: 480 min BASIN ID: B5 NAME: 2 YEAR DEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2.00 inches AREA. . : 0. 31 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 16. 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 4.93 Acres CN. . . . . 98.00 PEAK RATE: 2.05 cfs VOL: 0.74 Ac-ft TIME: 480 min BASIN ID: B6 NAME: 10 YEAR DEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5.24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2.90 inches AREA. . : 0. 31 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 16.30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 4.93 Acres CN. . . . . 98.00 PEAK RATE: 3.08 cfs VOL: 1.13 Ac-ft TIME: 480 min t 3/10/96 Bush, Roed & Hitchings, Inc. page 3 Raymond Industrial Center John E. Anderson, P.E. 92233 BASIN SUMMARY BASIN ID: B7 NAME: 25 YEAR DEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 .40 inches AREA. . : 0. 31 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 16. 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 4 .93 Acres CN. . . . . 98.00 PEAK RATE: 3 .65 cfs VOL: 1. 34 Ac-ft TIME: 480 min BASIN ID: B8 NAME: 100 YEAR DEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3.90 inches AREA. . : 0. 31 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 \ TIME OF CONC. . . . . : 16. 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 4.93 Acres CN. . . . . 98.00 PEAK RATE: 4.22 cfs VOL: 1.56 Ac-ft TIME: 480 min BASIN ID: B9 NAME: PTWQ VOLUME FOR WETPOND SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 24 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 0.67 inches AREA. . : 0. 31 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 80.00 TIME OF CONC. . . . . : 16. 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 4.93 Acres CN. . . . . 98.00 PEAK RATE: 0.54 cfs VOL: 0.20 Ac-ft TIME: 480 min J S 3/10/96 Bush, Roed & Hitchings, Inc. page 1 Raymond Industrial Center John E. Anderson, P.E. 92233 1 HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf-ACFt Acres 1 0. 314 490 10699 cf 5. 24 2 Ex 2 0. 888 480 22360 -cf 5.24 -- Iv `�e �x�sTi �U 3 1. 272 480 29624 c5 8U 372��3 Cf —5:24 - f_ _5• 24 lao (R CX�STtrJc� • 80 — 49081 Cf ----5:2 Z `�2 D6�IEloPEb 1�lFI o� 10 `j2_DEVE�?cC� �rJFI.OW . C 24 Z5 `�R bC'�Et�PED I t.tr � • 2�C-----480 -- � --- b7800--c -- ------- - -- 100 �fR• DEvp,oPEt7 1�.1F�v-� 9 0.544 $-O -8-51�c f_-.-..-__ --_�2- ----- PTv.►fl FotZ wETt�ND �lo�uvtiE 11 0. 153 1470 22217 c� 5:-2� toYsz PoNv REl�E7�S'E 12 O. 0 -3-10D-3 cf`_ _ _5 24 zS�R R>,1� �2ELEr�S£ 13 0.675 900 40325 C 5.24 \ao y� porwl_Et�S� �- bETE't.1T�o�.1 Pbh1D t7E5LyrJ Fd�va�� F�SNE'R,\�S DES\bi�l STAI.apR12'pS, � . p.lLpwAfly�E REI.ER5E F-P%TE FoR Ip `{GNIZ Dt'QC—:LoQC-D (NPl.ov� �c�up.LS Y2, P2s - DF-vs DPED T>oN4 2c.TE, �/Z PtzE-DE`IE�YED = to �lEpkiZ r7EvEl-oPrcb = 3 0 $LG+FS 17.ETEt.17�cN LIr5 � b. 1S'1�FS 2, ALL-DwA re3LE 'RELa0-P5E IZ'ATE5 FOR Z5 '(OPktZ lS�r-ID too�E+ 0E\/Et.!>-PE17 (Au s t 1-- oT (JE 6:qRe-PcTE-G-- -C'4Ni--1 TEE Vat - TEvG L-U Pere PEp.LL 1ZkTE6. ph., PRE bEvE LOPE r� ZS Y2 P�1� 1 2"12 GF5 17E TE 1,J TI otil PU IJ D FZE Uc S£= OZ = O 4210 C.G 5 ✓ F�zE - 'DC\PELD'SD \oc ® = I (o�Z GAS Pe Te tom►T\D S-1 Poi n = p ,(6-15 c f=5 ✓ 3. -F�+E DETEi-17, 10 .1 :PDQ\) �XGEEnS FtSI-�[�IES ST ►.�I�P�Zp VJt5TPvn1D VOL-UME ��Qv�2Ep �QvAI,S pTWQ 5TORNA V0LUVj4_= Von. Q = S 5 q• c, Yo t_.u►✓vE p�ov r p Ev : 24��4loGF c/ 2 3/10/96 Bush, Roed & Hitchings, Inc. page 2 Raymond Industrial Center John E. Anderson, P.E. 92233 STORAGE STRUCTURE LIST STORAGE LIST ID No. 1 Description: DETENTION POND ARCS rPONA /L\,vTcC.A Z> ES16S1 4-z "S"I , A ZF-EA. (0 -0 "7 G2-0 Sir -1 . o S °I O Z S F vv CT Po D �. o l0 2e1 SF �vo�= a 11 -1S15 - - I o ,0 12 `1 °12 S� r7G'CG►�'f�otil VvLur n� ��Qvt "'D I I , 0 13 8'12 SF r—olz too YsZ SToRPit 12 o 14 9 q 4 5F - -- - - -- r w ATEV-1 ELSW%T I o&j 13 r-, 5 I FOR 100 \m S TO'R K"'�' 14 -o I-7 F,0A = IZ,Oct I �•C�D iT►Ot�IA.� VoL-uME ?pzo�vlc�ED 1Co ,o t 3/10/96 Bush, Roed & Hitchings, Inc. page 3 Raymond Industrial Center John E. Anderson, P.E. 92233 DISCHARGE STRUCTURE LIST MULTIPLE ORIFICE ID No. 1 Description: FISHERIES DESIGN RELEASE Outlet Elev: 9.00 Elev: 9.00 ft Orifice Diameter: 1.8100 in. Elev: 12.00 ft Orifice 2 Diameter: 8.0000 in. OVC��LOu1 i I SU - 2 3/10/96 Bush, Roed & Hitchings, Inc. page 4 Raymond Industrial Center John E. Anderson, P.E. 92233 LEVEL POOL TABLE SUMMARY MATCH INFLOW ST DI <-PEAK-> STORAGE <--------DESCRIPTION---------> (cfs) (cfs) id id <-STAGE> id VOL (cf) 1/2-2 YR. FOR 10 YR . . . . . . . . . . 0.31 3.08 1 1 11.98 11 397 25 YEAR STORM . . . . . . . . . . . . . . . . 1.27 3.65 1 1 12.05 12 408 100 YEAR STORM . . . . . . . . . . . . . . . 1.68 4.22 1 1 12.09 13 415 File Basin Hydrograph Storage Discharge Level pool Bush, Roed & Hitchings, Inc. 2 } ROUTING COMPARISON TABLE MATCH INFLOW STO DIS PEAK PEAK OUT DESCRIPTION PEAK PEAK No. No. STG OUT HYD 1/2-2 YR. FOR 10 YR 0.31 3 .08 1 1 11.98 0.15 11 25 YEAR STORM 1. 27 3.65 1 1 12.05 0.43 12 100 YEAR STORM 1.68 4. 22 1 1 12.09 0.68 13 ______====>Done<====_______= F10 to Exit Available Memory remaining: 151037 bytes Current Data Set Name: a:\92233 File Basin Hydrograph Storage Discharge Level pool Bush, Roed & Hitchings, Inc. 2 ROUTING COMPARISON TABLE MATCH INFLOW STO DIS PEAK PEAK OUT DESCRIPTION PEAK PEAK No. No. STG OUT HYD 1/2-2 YR. FOR 10 YR 0. 31 3.08 1 1 11.98 0.15 11 25 YEAR STORM 1. 27 3 .65 1 1 12.05 0.43 12 100 YEAR STORM 1.68 4.22 1 1 12.09 0.68 13 ______====>Done<====_______= F10 to Exit Available Memory remaining: 151037 bytes Current Data Set Name: a:\92233 BUSH,ROED&HITCHINGS,INC. JOB CIVIL ENGINEERS &LAND SURVEYORS SHEET NO. OF 2009 Minor Avenue East Seattle,WA 98102 CALCULATED BY DATE (206)323-4144 BRH (206)323-7135 -Fax CHECKED BY DATE SCALE G .Lys �2 S L2S T, —a �02 TFfE Hyp&J4•UUL SoF�WA-reE v5E-U/ CALLv � { �D�•.1TS or.11 D.F. LU�2�lE o.foS 21� ,S � nJ�GC r ZZs - ✓. �") C2.�06 � 5 A 5,, ' o.6S71 r 3. 3p J 60_ o.bs D. �3 CIA --'� 71fc5C �- ��.� a., �--v .a F. Cv2�/� A-e� ,,.,PST ,.� /.►L%A2Av<<� 5��`►�/a-2F 7b G/'��.a� 77f� lc,i,/fo Go✓4>�"r->�A,F,c�" Z:�f c.-dvaa/� �orL ?JCS Sr'T�, PRODUCT 204-1(Single Sheets)205-1(PaM)®®Inc.Groton.Mass 01471 To Omer PHONE TOLL FREE I-800 225-6380 -IINGS,INC. JOB BUSH, ROED & H rC`I Z2i��- CIVIL ENGINEERS & LAND SURVEYORS SHEET NO OF 2009 Minor Avenue East Seattle,WA 98102 CALCULATED BY DATE �Q' 2� r' (206)323-4144 CHECKED BY < G DATE R (206)323-7135 ' Fax SCALE E�s�o � co,J i�� cra�..�J r✓,A�+ems .......... .... �E,J �►� .sue A�rt t�-k�,T-o� .... .... ....... .. �..........v>=12-s� -� ........ _.. _E�41✓ E.(Z _ r ..� ... _ . ._....................._ ......... .... .................. ...... ............ ...- - -- -- ........ .. L .... _. AM of►.�T.:__ �.1�J I�.�1'( .�, .... :_ .�i A _ P�(LG 1� •.. ...5�.. .:. A�� .... �'_► ��.............. /sEpjr-�1E►.1T...lo ...;.......Po.�-► P ._..... PES 1.Ca+�,. +_�-l- . . ,11.{'_ .. __T ...._.. -1.. _$....._ J4GR,6S_...i� 1To..__. ..... ..._. As�►Js ( a-rc - .......... TNT P.�ASi►� �� .., C_�.IoR.T.H ) _ 2 .53 Ace w A �/a = �. 1 v A �— o PRWX120A-1(S"b SMa)2W1 fP+dM)®.k GMIM M.oun to amp TDu FRFt 14*225 M _ .1/22/95 Bush . Roed & Hitchings . Inc. paae 1 Winmar John E. Anderson . P.E. storm disk-92233 HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf-AcFt Acres 1 0. 298 490 10148 cf 4 . 97 2 0. 843 480 21207 cf 4.97 3 1 . 206 480 28097 cf 4.97 4 1 . 596 480 35348 cf 4.97 5 1 . 955 480 30824 cf 4. 97 6 2 .932 480 46683 cf 4. 97 7 3 . 474 480 55555 cf 4. 97 8 4 .016 480 64455 cf 4.97 9 0. 515 480 8068 cf 4. 97 11 0 .129 1470 19342 cf 4.97 12 0 . 397 1450 26581 cf 4.97 13 0. 504 1030 35290 cf. 4.97 14 0. 281 480 6157 cf 1 .65 EAsT BAsii.1 15 0. 431 480 9441 cf 2. 53 aoe-TH 6AS1►.� 16 0 , 511 480 11194 cf 3. 00 wlEs�r Soa ,A KING COUNTY , WASHINGTON , SURFACE WATER DESIGN MANUAL 5.4.5.1 SEDIMENT TRAP Code: ST Symbol: Purpose To remove sediment from runoff originating from disturbed areas of the site. Sediment traps are typically designed to only remove sediment as small as medium silt (0.02 mm). As a consequence, they usually only result in a small reduction in turbidity. Conditions of Use 1. A sediment trap shall be used where the contributing drainage area is 3 acres or less. Design and Installation Specifications 1. See Figure 5.4.5.11A for detail. 2. If permanent runoff control facilities are part of the project, they should be used for sediment retention (see the introduction to this section). 3. To determine the trap geometry, first calculate the design surface area (SA) of the trap, measured at the invert of the weir . Use the following equation: SA = FS(Q2/Vs), where: Q2 = Design inflow based on the peak discharge from the developed 2-year, 24-hour ' design storm from the contributing drainage area as computed in the hydrologic analysis. The 10-year, 24-hour design storm shall be used if the project size, expected timing and duration of construction, or downstream conditions warrant a higher level of protection. If no hydrologic analysis is required, the rational method may be used (Section 4.3.3). Vs = The settling velocity of the soil particle of interest. The 0.02 mm (medium silt) particle with an assumed density of 2.65 g/cm3 has been selected as the particle of interest and has a settling velocity (Vs) of 0.00096 ft/sec. FS = A factor of safety of 2 to account for non-ideal settling. Therefore, the equation for computing surface area becomes: SA =2 x Q2/0.00096 or 2080 square feet per cfs of inflow NOTE: Even if permanent facilities are used, they must still have a surface area that is at least as large as that derived from the above formula. If they do not, the pond must be enlarged. 4. To aid in determining sediment depth, all traps shall have a staff gauge with a prominent mark 1 foot above the bottom of the trap. 5.4.5.1-1 11/94 KING COUNTY , WASHINGTON , SURFACE WATER DESIGN MANUAL } FIGURE 5.4.5.1A SEDIMENT TRAP SURFACE AREA DETERMINED - AT TOP OF WEIR 4' MIN. 1 1' MIN. OVERFLOW ,fy 1' MIN. I1 1' MIN. FLAT BOTTOM 3/4"-1.5' 2"-4" ROCK%RIPRAP! WASHED GRAVEL GEOTEXTILE NOTE: TRAP MAY BE FORMED BY BERM OR BY PARTIAL OR COMPLETE EXCAVATION DISCHARGE TO STABILIZED CONVEYANCE, OUTLET OR LEVEL SPREADER CROSS-SECTION �+- - 6' MIN. III-III-III—III—III—II 1' MIN. DEPTH OVERFLOW SPILLWAY -III-II +II-II Ii=iir—iii=ii►=1i1=1IEi III—Iii=i►i=1i�iTi=iI(— NATIVE SOIL OR I I I r, (� ( MIN. 1' DEPTH COMPACTED BACK FILL ��I 2"-4 ROCK _ MIN. 1' DEPTH 3/4"-1.5" cEOTExT►LE ' I—I II—I II—I II— IE EE 1 I=III WASHED GRAVEL II a -III-1 I�I(1-III-1 I l-1 I l-1 I II I f=l TRAP OUTLET Maintenance Standards 1. Sediment shall be removed from the trap when it reaches 1 foot in depth. 2. Any damage io the trap embankments or slopes shall be repaired. 5.4.5.2 SEDIMENT POND n Code: SP Symbol: Purpose To remove sediment from runoff originating from disturbed areas of the site. Sediment traps are typically designed to only remove sediment as small as medium silt (0.02 mm). As a consequence, they usually reduce turbidity only slightly. Conditions of Use 1. A sediment pond shall be used where the contributing drainage area is 3 acres or more. 5.4.5.2-1 11/94 BUSH,ROED& HTTCHINGS,INC. 1O8 CIVIL ENGINEERS& LAND SURVEYORS SHEET No. OF 2009 Minor Avenue East CALCULATED BY DATE Seattle,WA 98102 (206)323-4144 CHECKED BY DATE B R H (206)323-7135 - Fax SCALE �OY J�J�� i� /1jY'--t �JG�V�•�-G I- `i �rJCLs� __gq�t►-� -- 'L_ x Sl I_ c/�s D. 00®_`1 w .. _ _ .... . ...........__ .. ----- ..... ...... .. .. .. .._... . 31 D .... .. . - .� --s _.. .. . --... ............. - - .... .. _ _._..... ... ............ .... ........ S �f�St o .oa0_5 AS _ 5 a: _ .. ... . ... - - ___. ,�' 1JiL S-�o _ r'--e(L 0��-c�Pl✓ _ Go�.lOi►toS. . PRODUCT M41 rO SMOI N5 I PWWi®*h crwn wA 01471 is oroK PfM rou FFE 14*2254 eo 04/17/96 STORM SEWER SUMMARY REPORT PAGE 1 OF 2 RAYMOND CENTER FILE: 92233C.STM RAINFALL FILE: CHARTIO.RND 25 YEAR DESIGN STORM I = 16.930/ ( To + 5.200) ^ 0.792 LINE ID I FLOW RATE INFO I PIPE INFO I HYDRAULIC INFO LINE/1 DESCRIPTION JINC ARIRUNOFPCIINLTIMEIINLT IIINC CIAI INPUTQ JUNIFORMISIZE/INVERT IPIPE I NVAL JHGLSL.OPEJHYD GRD I VEL DOWNLINEf ITOT ARIWEIGHTD1 Tc ITOTL 11TOT CIAO TOTALQ IFLOWCAPITYPE JUP/DOWN (LEN JINVSLOPJ JLC JUP/DOWN JUP/DOWN (ec) C I (min) l(in/h)l (cfs) I (cfs) I (cfs) l(in) I (ft) l(ft) l(ft/ft)l (ft/ft)l (ft) I (ft/6) 1 cbl to pond 1 0.01 0.901 0.001 4.591 0.001 0.001 1 24DI 9.141 381 0.0131 0.0011 12.041 2.41 DNLN - O 1 5.41 0.901 15.271 1.551 7.571 7.571 13.81 24DI 9.001 1 0.0041 1.00 1 12.001 2.41 2 cb2 to cbl 1 0.41 0.901 0.001 4.591 1.531 0.001 1 18DI 9.411 721 0.0131 0.0041 12.451 3.97 DNLN - 1 1 5.01 0.901 14.971 1.571 7.021 7.021 6.41 18DI 9.141 1 0.0041 1.00 1 12.131 3.97 3 cb3 to cb2 1 0.31 0.901 0.001 4.591 1.401 0.001 1 18DI 10.251 2271 0.0131 0.0021 13.121 2.54 DNLN = 2 1 3.01 0.901 13.491 1.671 4.491 4.491 6.41 18DI 9.411 1 0.0041 1.00 1 12.701 2.54 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4 cb4 to cb3 1 0.61 0.901 0.001 4.591 2.271 0.001 1 18DI 11.021 2071 0.0131 0.0021 13.551 2.40 1 DNLN - 3 1 2.61 0.901 12.041 1.781 4.241 4.241 6.41 18DI 10.251 1 0.0041 1.00 1 13.221 2.40 5 1 cb5 to cb4 1 0.61 0.901 0.001 4.591 2.401 0.001 1 18DI 11.411 1051 0.0131 0.0011 13.761 1.98 1 DNLN = 4 1 2.11 0.901 11.151 1.851 3.501 3.501 6.41 18DI 11.021 1 0.0041 1.00 1 13.641 1.98 6 1 cb6 to cb5 1 1.01 0.901 0.001 4.591 4.211 0.001 1 18Dj 11.851 1181 0.0131 0.0011 13.901 1.53 .� DNLN - 5 1 1.51 0.901 9.841 1.981 2.711 2.711 6.41 18DI 11.411 1 0.0041 1.00 1 13.821 1.53 7 cb7 to cb6 1 0.51 0.901 6.301 2.451 1.101 0.001 1 12DI 13.461 3231 0.0131 0.0011 14.291 1.67 DNLN - 6 1 0.51 0.901 6.301 2.451 1.101 1.101 2.51 12DI 11.851 1 0.005I 1.00 1 13.941 1.40 S I CB9 - CBI 1 0.31 0.901 0.001 4.591 1.201 0.001 1 12DI 11.211 791 0.0131 0.0011 12.181 1.16 1 DNLN - 1 1 0.41 0.901 7.711 2.231 0.911 0.911 5.81 12DI 9.141 1 0.0261 1.00 1 12.131 1.15 1 1 ( 1 1 1 1 1 1 1 1 1 1 1 1 9 I CBS - CB9 1 0.21 0.901 6.301 2.451 0.351 0.001 1 12DI 14.211 1141 0.0131 0.0201 14.541 2.27 1 DNLN - 8 1 0.21 0.901 6.301 2.451 0.351 0.351 5.81 12DI 11.211 1 0.026I 1.00 1 12.201 0.45 10 1 CB10 -CB2 1 0.71 0.901 0.001 4.591 2.811 0.001 1 12DI 10.891 1311 0.0131 0.0071 13.591 3.73 1 DNLN - 2 1 1.61 0.901 9.461 2.021 2.931 2.931 3.81 12DI 9.401 ( 0.0111 1.00 1 12.701 3.73 11 1 CB11 - CB10 1 0.31 0.901 0.001 4.591 1.201 0.001 1 12DI 14.201 2931 0.0131 0.0041 14.841 3.49 1 DNLN = 10 1 0.91 0.901 7.811 2.221 1.861 1.861 3.81 12DI 10.891 1 0.0111 1.00 1 13.811 2.37 1 1 1 1 1 1 1 1 1 1 1 ( 1 1 1 12 1 CB12 - CB11 1 0.31 0.901 0.001 4.591 1.401 0.001 1 12DI 15.361 1021 0.0131 0.0081 15.851 3.49 1 DNLN a 11 1 0.61 0."1 7.171 2.311 1.331 1.331 3.81 12DI 14.201 1 0.0111 1.00 1 15.031 1.91 1 1 ( 1 1 1 1 1 1 1 1 1 1 1 1 13 1 CB13 - CB12 1 0.31 0.901 6.301 2.451 0.661 0.001 1 12DI 16.531 1021 0.0131 0.0091 16.991 2.75 1 DNLN = 12 1 0.31 0.901 6.301 2.451 0.661 0.66I 3.8l 12DI 15.361 1 0.0111 1.00 1 16.041 1.17 04/17/96 STORM SEWER SUMMARY REPORT PAGE 1 OF 2 RAYMOND CENTER FILE: 92233C.STM RAINFALL FILE: CRARTIO.RND 100 YEAR DESIGN STORM I = 21.753/ ( To + 5.600) ^ 0.787 LINE ID I FLOW RATE INFO I PIPE INFO I HYDRAULIC INFO LINESI DESCRIPTION ZINC ARIRUNOFPCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL IHGLSLOPEIHYD GRD I VEL DOWNLINE# ITOT ARIWEIGHTDI To ITOTL IITOT CIAO TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I (ac) I C I (min) I(in/h)I (of&) I (of&) I (oft) 1(in) I (ft) I(ft) I(ft/ft)1 (ft/ft)1 (ft) I (ft/6) I I I I 1 I I I I 1 I I I 1 I 1 I cbl to pond I 0.01 0.901 0.001 5.611 0.001 0.001 1 24DI 9.141 381 0.0131 0.0021 12.081 3.34 1 DNLN - 0 1 5.41 0.901 13.341 2.151 10.501 10.501 13.81 24DI 9.001 1 0.0041 1.00 1 12.001 3.34 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 cb2 to cbl 1 0.41 0.901 0.001 5.611 1.871 0.001 1 18DI 9.411 721 0.0131 0.0091 12.871 5.50 1 DNLN - 1 1 5.01 0.901 13.131 2.171 9.711 9.711 6.41 18DI 9.141 1 0.0041 1.00 1 12.261 5.50 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 cb3 to cb2 1 0.31 0.901 0.001 5.611 1.721 0.001 1 18DI 10.251 2271 0.0131 0.0031 14.111 3.46 1 DNLN = 2 1 3.01 0.901 12.041 2.281 6.121 6.121 6.41 18DI 9.411 1 0.0041 1.00 1 13.341 3.47 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4 1 cb4 to cb3 1 0.61 0.901 0.001 5.611 2.781 0.001 I 18D1 11.021 2071 0.0131 0.0031 14.911 3.23 1 DNLN = 3 1 2.61 0.901 10.981 2.391 5.701 5.701 6.41 18D1 10.251 1 0.0041 1.00 1 14.301 3.23 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 1 cb5 to cb4 1 0.61 0.901 0.001 5.611 2.931 0.001 1 18DI 11.411 1051 0.0131 0.0021 15.281 2.64 1 DNLN - 4 1 2.11 0.901 10.311 2.471 4.661 4.661 6.41 18D1 11.021 1 0.0041 1.00 1 15.071 2.64 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 6 1 cb6 to cb5 1 1.01 0.901 0.001 5.611 5.151 0.001 1 18DI 11.851 1181 0.0131 0.0011 15.531 2.01 1 DNLN = 5 1 1.51 0.901 9.331 2.591 3.551 3.551 6.41 18DI 11.411 1 0.0041 1.00 1 15.391 2.01 I I I I I I I I I I I I ( I I 7 1 cb7 to Cb6 1 0.51 0.901 6.301 3.101 1.401 0.001 1 12DI 13.461 3231 0.0131 0.0021 16.131 1.78 1 DNLN = 6 1 0.51 0.901 6.301 3.101 1.401 1.401 2.51 12D1 11.851 1 0.0051 1.00 1 15.591 1.78 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 8 I CB9 - CBI 1 0.31 0.901 0.001 5.611 1.461 0.001 1 12DI 11.211 791 0.0131 0.0011 12.341 1.48 DNLN = 1 1 0.41 0.901 7.571 2.861 1.161 1.161 5.81 12DI 9.141 1 0.0261 1.00 1 12.261 1.48 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 9 I CBS - CB9 1 0.21 0.901 6.301 3.101 0.451 0.001 1 12DI 14.211 1141 0.0131 0.0191 14.591 2.44 1 DNLN - 8 1 0.21 0.901 6.301 3.101 0.451 0.451 5.81 12D1 11.211 1 0.0261 1.00 1 12.371 0.57 I I I I I I I I I I I I I I 10 1 CB10 -CB2 1 0.71 0.901 0.001 5.611 3.431 0.001 1 12DI 10.891 1311 0.0131 0.0111 14.761 4.70 1 DNLN = 2 1 1.61 0.901 9.691 2.551 3.691 3.691 3.81 12D1 9.401 1 0.0111 1.00 1 13.341 4.70 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 CB11 - CB10 1 0.31 0.901 0.001 5.611 1.461 0.001 1 12D1 14.201 2931 0.0131 0.0041 16.361 2.98 1 DNLN = 10 1 0.91 0.901 7.981 2.801 2.341 2.341 3.81 12D1 10.891 1 0.0111 1.00 1 15.101 2.98 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 12 1 CB12 - CB11 1 0.31 0.901 0.001 5.611 1.721 0.001 1 12DI 15.361 1021 0.0131 0.0021 16.731 2.15 1 DNLN - 11 1 0.61 0.901 7.151 2.941 1.691 1.691 3.81 12DI 14.201 1 0.0111 1.00 1 16.501 2.16 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 13 1 CB13 - CB12 1 0.31 0.901 6.301 3.101 0.841 0.001 1 12DI 16.531 1021 0.0131 0.0021 17.061 2.66 1 DNLN - 12 1 0.31 0.901 6.301 3.101 0.841 0.841 3.81 12DI 15.361 1 0.0111 1.00 1 16.811 1.07 PR0 FILE Lin-e 1 cb 1 to pond 20 [F1] Menu 18 Natural ground slope 0.5337S 0 w 1-0 w HO3L. slope 0.11237. 12 — 10 38 ft. of 24 in. pip Q 0.370% 8 0 5 10 15 20 25 30 35 40 sTTI c:)N PRO FILE Lute+ 2 cb2 to cb 1 20 [Flj Menu 1$ z Natural ground slope -1.46Pl.' 16 w 14 wHGL slope 0.el47% 10 72 fi. of 18 in. pipe « 0.370l4 8 0 10 20 30 40 50 60 70 60 �T.P�TI O N PRE FILE Lille 3 cb3 to cb2 20 [F1] M anu 18 Natural ground slope 0.5532o' C r--a 16 w 14 HC3L slope O.183�0 12 228 ft. of 18 in. pipe (off 0.3701;1. 14 S 0 50 100 150 200 250 STATI�N PRE FILE Ling 4 cb4 to cb3 a• 20 [Flj M enu 18 atural ground slope -1.54% 16 w14 HOL. slope 0.168,% w 12 208 At of 18 in. pipe rl 0.370% 10 8 0 50 100 150 200 STATION PRE FILE Lin-e 5 cb5 to cb4 s 16 [F1] Menu 15 z Natural gzound slope 0.00% 14 HOI E slope O.111% w 13 w106 ft. of 18 in. pipe 0.970 7. 12 11 10 0 20 40 60 80 100 120 STATI O N I'R�FILE 1�� Line 6 cb6 to cb5 16 [F1] Menu 15 �i Natural ggound slope -0.08% Q F--r 14 - w 13 a 118 ft. of 18 in. pipe Lab 0.37Q% w 12 11 10 L 0 20 40 60 00 100 120 ST-4kTI 0 N PR(]FILE Lines 7 cb7 to cb6 • 7,. 18 (F1] Menu 17 z 16 Natured ground slope ❑.59a7e 15 323 ft. of 12 in. pipe � C.500%0 _. - - - _.. _.. _.. _.. _. _.. _.. - I�GL sla o w 13 12 11 10 0 50 100 150 200 250 300 350 sTATI C)N PRE FILE Lines � �B$ - CBS 18 [F1] 17 Nmtural gxaund 31ope 0.26% Menu 16 Hi �4 15 . - 115 ft. of 12 in. pipe 2.61 w 14 _ w 13 _, ---FIC C.. slope 2. e 12 11 10 0 20 40 60 80 100 120 STATION PRE FILE 1* � Line 14 C810 -CB2 18 [F1] Natral gg ound slope 0.19% Menu 16 u 14 HGL 31ope 0.67670 w 12 32 ft. of 12 in. pipe (P 1. 1 10 8 0 20 40 60 80 100 120 140 Lines 11 CB 11 - CB 10 22 [FS] Menu 20 z Nmtursl gxo=d slope 1.04`y 18 16 w293 ft. of 12 in. pipe Cgs 1. 1307,L _. -" r-� 14 - - - - - - w - - HGI_ 31 12 10 8 0 50 100 150 200 250 300 STALTI O N PR.�FILE � 1>Line 12 CB 12 - CB 11 21 [F11 Menu 20 Namtural ground slope O.00%Q 19 F--1 18 w 17 a 103 ft. of 12 in. pipe (g> 1. 130 X. is - - - - -i46L slope 0.798 14 13 0 20 40 60 80 100 120 ST2k7I c)N PRE FILE •13 Line 13 CB 13 - CB 1z 21 [F1] Menu 20 Natural ground 510pe 0.00 i'o 19 18 103 ft. of 12 in. pipe �(9) 1. 13070 17 slope 0.92 16 15 . 14 0 20 40 60 80 100 120 S,TA-I-T I o N