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HomeMy WebLinkAbout03244 - Technical Information Report - Prelim Storm Drainage Calculations � � ��� �, � ��.{�-- � "�,r✓'� r- t V �� Core Design,Inc. CORE �4711 N E 29th Place Suite #101 � DESIGN Bellevue, Washington 98007 425.885.7877 Fax 425.885.7963 � N PRELIMINARY STORM DR.AINAGE a CALCULATIONS P�`NN,NG oE`��c��°���o � C� 1� �� 0 Q FOR THE C����' �� FOTHERINGILL SHORT PLAT RENTON, WASHINGTON n��,�Y � � \�� 5 Wns�O ��� � �� � 'P�i"az � . . �Sj�NAL�'G �CPIRES 12/14i;�> Prepared by: James A. �Iorin, P.E. Project�Ianager: Robert H. Stevens, P.E. Core Project No.: 0�1108 I)ate: October 200� �NGINEERING PiANNING SURVEYING �3 2s/.r/ FOTHERII�IGILL SHORT PL�T TABLE OF CONTENTS 1.0 Project Overvie�r � ...0 Off-Site Analvsis 3.0 Flow Control/Water Quality Facility Analysis and Design 3.1 Hydraulic Analysis 3.2 Existing Conditions 3.3 Developed Conditions 3.4 Detention Routing Calculations 3.5 Water Qualit�� Volume I ���� `�..�= 1.0 PROJECT O�'ERVIE��' The Fotheringill Short Plat is located in Section i�, Township 23 �iorth, Rang � East W.M. near the intersection of 138`h AVE, SE and SE 132°d ST in Renton, Washington (See Figure 1-Vicinity Map). The site is approximately 0.56 acres. The project proposes to construct 4 lots with related utility services. The supporting roads, curb, gutter, and sidewalk are to be constructed durinQ construction of the Laurelhtirst Plat . See Figure ?- Site Plan, for the overall site plan. The existing site is a mixture of forest and pasture with a home and outbuildings scattered through out the property. See Figure 3- Site Landcover for a scaled aerial map of the property. This property is tributary to the proposed detention/�vater quality pond in the Laurelhurst Plat and is included in the original pond model as area T3. See figure 3a — Site Landcover Tabulation for a detailed e�hibit of this project and the area calculations for modeling the pond. The Ciry of Renton requires Level ? tloti�- control and the Basic Water Quality menu far the site as specified in the 1998 Kin Countv Surface Water Design Manual. The on-site generated runoff will be conveyed to the combined detentioni water quality pond for the Laurelhurst project. All drainage discharge from the pond will be conveyed via pipe to Maplewood Creek as shown in the plan. See the Laurelhurst T.I.R. for the complete design of pond. ----., �o�� �._ J:120021020521Engr�02052C101.dwg, 10/27/2004 11:07:11 AM,jam; KIP 6000.pc3 z m z UNI01� q� ) i ' NE � � I � � n � tn � I � � i Z � J BREME rp� A� II � o � m � — o i � � � m DUVq�! FF A � � z w � '� �, Z � � � p � m � N z (� Z ---I � � --i � ti 144TH AVE SE 146 TH A VE SE � r.r. � � � � M� SEC. 15, TWP. 23N, RGE SE., W.M, . -- , ; --� __--- ��- � . ---- -_. .�__e -- - --�----- �� ( -- ----- ------ --_-----�; ; � [f ) i '' I ` � NE 1st ST � � � � -- --__ � � I ' N Ii � i � � � , ` i 1 ' ' ° , r { i � f i ��� � M � �° _ �i�E �� � ZL � � o ioo 20 +a � � I , �� t-� j � � ;�\ \"�..� � ! i � �i V _ — _ — _ _ _ _ _ _ — — _ _ _ _ _ _ Ej ' 1� � E � `� �� �, i i � � � - - - - - � �� �t � i i � � � � � i i i � �. i � /� � i i � � ; T � � 3 � � i � ' � � , /-1 � t ; I � � � � � � � �i � i i � ► i i � � �� � � i 4i i � n � � i ` i � � � i � � i 2 i i 3 � w ' i � � , , � � I ; i � 6533 5F. i � 4688 SF. I I 5r✓-22 S.F. i � � ,f � � I Q , � �� � I I i � J � �� � I � ; ' ; � � � I I � J i '� � �-- - - - - - - - - - -� L - - - - - - I i �� I �� - - - --� Q { � ; I ! �� `; E `"�` I � � ;i � i � _ ;� 4� � ' � ,, o �� � � FIGURE 2 o I , ; � � � � i � � � �� � i � � � � . ^ �� I � /�-- - - - - - - - - - - - - - - - - ! � i �� � i �,�� I �� � � ' � ;.71!NE 29rh Ploce,1?�07 �I, Oi �'.J;i / � � ( � s�u�.�,�,w�,n�»sr�, 9aco� �I � /��. �� / I � � a�s.eas.�an Fa:nss.ess.�9a3 ' o i�+ // I +� � � �DESIGN 1 ) ENGiNEERlNG PLANNfNG SURVEYING �. � n � � � � , i-r _ ;,� i � : ; � ' � ��f /� 6816 Sr. � ! � � �� � � � ��� o ; / � � ' � � ` ( j FO THER/N G/L L SH OR T PL�1 T %i-!l. : ''.I': . � I ' 1 � . i f I � � W� � �/ - - - - - - - - - - ! �g � ,�`,�''� W� �� Y'-.___,,' - - - - - - - - - - - - -- - - - - - _J DATE SEPT, 2004 SHEET � 00 ------ ; O` � ; CES�GNEC ✓AM 1 1 c y o - 'v � PRCJECT NUMBER o � �R A.'��1�: JAM N y —_ n��nsz SEC. 15, TWP, 23N, RGE 5E., W.M. `�` _ � Q � . .� _ _ _ - - _ ; , 4 A . � - t � - z , , - _' � , - � � ., _ ��� ; -.. �� � � N _ _ . _ ..— 4. � � — _ `•�:L �`x� �`.-��-��.,i[l �� - - F� -- p� - ___ � ..... _ -- - _ - - � _ _ p, - �`:.e��;� .- � _ _ _��-- � _` �� _ - SEC. 15, TWP, 23N, RGE5E., W.M. I � ._ � - AREA TA FROM LAURELHURST I' BU LATIONS ( ) � �� -�� _ ��. �� !��� ����� , ;,�,'��_ � � �� � �� � PREDFVELOPED � � '�� - � � - � �f � - � � 2.0 OFF-SITE ANALYSIS tipstream Tributary area There is no upstream area contributing to this property. See the Technical Information Report for the Laurelhurst Plat for a complete description of the drainage basin contributing to the pond. Downstream Analysis See the Technical Information Report for the Laurelhurst Plat far a complete description of the drainage basin contributing to the pond. � �..: �-;._ - . � � . � --"� �'�RE .� 2- 1 3.0 FLOd�' COVTROL. / `�:�TER QL.aLI'TY F�CII_ITY �N:�LYSIS / DESIGN 3.1 HYDRf1ULIC A1�IALYSIS The drainage analysis was modeled using the King County Runoff Time Series (KCRTS) software version 42. The site soils are Alderwood (AgC), KCRTS �oup, Till. The site is located in Sea-Tac rainfall region «�ith a sale factor of 1.0. See the appendiY for the soils map and scale factor e�hibits. 3.2 EYIS�'I�1G CONDITIONS The area was referred to as area T3 in the Laurelhurst Plat basin. By using the survey topographic survey for the project the measured exiting impervious area is 0.20 acres. This information was used to produce the Predeveloped Runoff Timeseries (PREDEV) in the KCRTS program. (From Laurelhurst TIR} -- ,-_ ' i; �,:-' . _. .-�- �� AREA T3 (Fotheringill SP) Till-forest 0.10 ' Till-pasture 0.26 . Impervious Area(measured) 0.20 . Subtotal: 0.56 , ----�� �oRE � ..y.__, ._ 3- 1 '' ,i PREDEVELOPED CONDITIONS Total area =30.82 ac (Com lete Summar�- of Areas} Ground Ca��er Area (ac) Till-forest 12.34 • Till-pasture 14.97 ' Impervious Area(measured) 3.�1 • See the KCRTS calculations in the Appendix for the detail See the Laurelhurst TIR for the complete listing of the timeseries used to model the predeveloped 30.82 Ac basin which this 0.56 Ac parcel is a part. �� �'�RE �� 3- 2 ! 3.3 DEVELOPED CONDITIONS The developed site will consist of 4 homes on 0.56 acres. L'sing 4,000 sf of impervious area per lot the resultant impervious area is: (4 x 4,000 )/ 43560 = 0.37 Ac Impervious The remainder of the area was assumed to be Qrass: 0.56—0.37 = 0.19Ac Grass This information was used to produce the Developed Runoff Timeseries (DEV) in the KCRTS pro�am. The tabulation belo„ ��as the original Laurelhurst areas «-�ith T3 revised as sho���n. _ - (from Laurelhurst TIR, amended as shown) AREA T3 (Fotherin ill Short Plat) Till-forest 0.00 Till-�ass 0.19 Impervious Area 0.37 Subtotal: 0.56 ; .�:�:-. - _.•f�,�, : _,:r;�.. _�-- �coRE ,�, 3- 1 ` � DEVELOPED C0�IDITIOI�TS Total area= 36.32 ac (Com lete Summarv of.=�reas) Ground Cover Area (ac) Till-forest 0.93 Till-�ass 15.17 Impervious Area 20.22 See the KCRTS calculations in the Appendix for the detail Time Series File:dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak -- Peaks - - Rank Return Prob (CFS) (CFS) Period 6.29 6 2/09/01 2:00 12.82 1 100.00 0.990 5.02 8 1/05/0216:00 7.73 2 25.00 0.960 7.58 3 2/27/03 7:00 7.58 3 10.00 0.900 5.32 7 8/26/04 2:00 6.67 4 5.00 0.800 6.43 5 10/28/0416:00 6.43 5 3.00 0.667 6.67 4 1/18/06 16:00 6.29 6 2.00 0.500 7.73 2 10/26/06 0:00 5.32 7 1.30 0.231 12.82 1 1/09/08 6:00 5.02 8 1.10 0.091 Computed Peaks 11.12 50.00 0.980 l„'� CORE ��. 3- 2 3.=t DETENTIO\ROL"TING CALCLZATIO�S �I'he City of Renton requires that the Level 2 Flow Control standard applies to this project. This standard requires that the proposed pond outfall match the 2-year and 10-year predeveloped release rate and the not exceed the frequency and dtiration from '.-;� the ?-year up to the 50 year evert. li sing the appropriate release rates the developed timeseries «�as modeled in a pond with 2:1 sides slopes, 12-feet of water depth and a pond bottom of 21,762 sf (234 x 93). A riyo orifice control structure was design to meet the release rates and frequency duration standards. See the Appendix of this report for the detailed KCRTS calculations. Tlle resultant pond volume required�vas 3�5,?84 cf. The volume pro��ided on the plan is �6�,?�l cf. Therefore, the pond, as sho«�n on the plans for Laurelhurst is adequate to provide detention for the Fotheringill Short Plat. No change is required in the desi� of the control structure for the Laurelh�irst Plat to accommodate the increased runoff from this ��'� acre parcel. Live Storage 3�5,284 cf required 363,281 cf provided -- � �CCJR� .�_ 3- 3 ' 3.5 WATER QL�.=�LITY VOLU��IE. T'otal area = 36.32 Ac Impervious= 20.22 Ac Forested= 0.93 Ac Lawn= 15.1? Ac The basic ��-ater quality menu (KCSWDV16.4.1.1,page 6-68): Vr= [0.90*Ai + 0.25*Ag + 0.10*Af] x R/12 V"r= [0.90*(?0.?2*43560) + 0.25*(15.17*43560) + Q.10(0.93*43564 ] Y R/12 V"r = (792,70� + 165,201 + 4,051) x 0.47 / 12 Vr=37,676 `'b =3 x Vr �'b = 3 * 37,676 V"b = ll3.029 cf Dead Stora�e 113,029 cf required 122,008 cf pro��ided -- -�,� �o�� �- - 3- 4 W �o � _ � � A � � w � � a a � Rete�tion/Detention Facility ^ype of Facilitl: Dete�tion Pond Side Slope: 2 .00 H:lV Pond Bottom Length: 234.00 ft Pond Bottom rdidth: 93 .00 ft Pond Bottom Area: 21762 . sq. ft Ton Area at 1 ft. FB: 40356. sq. ft 0.926 acres Effective Storage Depth: 11.35 f� Stage 0 Eleva�ion: 365.00 f� Storage Volume: 339047. cu. ft 7.783 ac-ft Riser Head: 11.35 ft Riser Diameter: 24 . 00 inches Number of orifices: 2 Full Head Pipe Orif-ce � Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 3 .06 0.857 � 8.70 6.00 1.589 8.0 Top Notch Weir: None Outflc��v Rat�ng Curve: Nor.e Stage Elevat_on Storage Discharge Fercolation Sur= Area (ft; (ft) (cu. ft) (ac-f t) (cfs) (cfs} (sq. ft) 0 . 00 365.00 0. O. 000 0.000 0.00 21762 . 0 . 03 365.03 653. 0.015 0.045 0.00 21801. 0 . 06 365.06 1308. 0.030 0.064 0.00 21841. 0 . 10 365.1C 2183. 0.050 0.079 0.00 21893 . G . 13 365.13 2840. 0.065 0.091 0.00 21932 . 0 .16 365.16 3499. 0.080 0.102 0.00 21972 . 0 . 19 365.19 4158. 0.095 0.111 0.00 22011. 0 .22 365.22 4819. 0 .111 0.120 0.00 22051. 0 .26 365.26 5702. 0 .131 0. 129 0.00 22103 . 0 .45 365.45 9926. 0.228 0. 170 0.00 22354 . 0 . 64 365.64 14197. 0.326 0.204 0.00 22606 . 0 . 83 365.83 18516. 0.425 0.232 0.00 22859 . �. 02 366_02 22883 . 0.525 0.258 0.0a 23113 . i.22 366.22 27533. 0.632 0.281 0.00 23382 . 1.41 366.41 32000. 0.735 0.302 Q.00 23638. 1 .b0 366.60 365�5. 0.838 0.322 0_00 23896. 1 .79 366.79 41080. 0.943 0.341 0.00 24155. 1 . 99 366.99 45938. 1.055 0.359 0. 00 24428 . 2 . i8 367.18 50604. 1.162 0.376 0. 00 24689. � . 37 367.37 55320. 1.270 0.392 0. 00 24952 . 2 . 56 367.56 60086. 1.379 0.407 0. 00 25215. 2 . 76 367.76 65157. 1.496 0.422 0. 00 25494. 2 . 95 367.95 70026. 1.608 0.437 0_00 25760. 3 . 14 368 .14 74946. 1.721 0.451 0.00 26027. 3 .33 368.33 79917. 1.835 0.465 0 .00 26295. 3 .53 368.53 85204. 1.956 0.478 0 .00 26579. � 3 . 72 368.72 90280. 2.073 0.491 0 .00 26849. i 3 . 91 368 . 9- 951C? . 2 . �9� 0 .503 0 .00 ''�1L1 . �I 4 .10 369.10 _00586. 2.309 0.515 0 .00 27394 . 4.30 369.30 106093 . 2.4's6 0.527 0.00 27682 . 4 .49 369.49 111379. 2 .557 0.539 0.00 27957 . 4 .68 369.68 116717. 2.679 C.551 0. 00 28234 . 4 .87 369.87 122108. 2.803 C.562 0. 00 285i1. 5.06 370.06 127551. 2.928 C.573 O. CO 28790. 5 .26 370.26 133339. 3 .061 0.583 O. CO 29085 . 5 .45 370.45 138892 . 3 .169 0.594 O. CO 29366. 5 .64 370.64 144498. 3 .317 0_604 0_CO 29648. 5.83 370.83 150'S8. 3 .447 0.615 0.00 29931. � 6_03 371.03 156174 . 3 .585 0.625 0. 00 30231. 6.22 371.22 161945. 3 .7Z8 0.635 0.00 30517. 6.41 371.41 167771. 3 .851 0.644 0.00 30804 . 6.60 371.60 173651. 3 .986 0.654 0.00 31092 . 6 .80 371.80 179900. 4.130 0.663 C_00 31396. 6 .99 371.99 185892. 4.268 0.673 0.00 31687. 7.18 372.18 191941. 4.406 0.682 0 .00 31978. 7.37 372.37 198044. 4 .546 0.691 0.00 32271. 7 .57 372.57 204529. 4.695 0.700 0. 00 32580. 7 .76 372.76 210748. 4.838 0.7a9 0 .00 32876 . 7.95 372.95 217022 . 4 .982 0.7I8 0.00 33172 . 8 .14 373 .14 223353 . 5.127 0.726 0.00 33469. 8 .33 373 .33 229741. 5.274 0.735 0. 00 33768 . 8 .53 373 .53 236526. 5.�30 0.743 0 . 00 34083 . 8 .70 373 .70 242343. 5.563 0.751 0.00 34353 . 8 .76 373 .76 244407. 5 .611 0.764 0. 00 34448. 8 .83 373 .83 246822 . 5.666 0.798 �. 00 34559. 8 .89 373 .89 248898. 5.714 0 .851 0. 00 34655. 8 .95 373 .95 250980. 5.762 0 .924 0. 00 34750. 9.01 374 .01 253068. 5.810 1.010 0 . 00 34846. 9.08 374.08 255512 . 5.866 1 .360 0 . 00 34958. 9.14 374.14 257612 . 5.914 1.420 0 . 00 35054 . ' 9.20 374.20 259718. 5.962 1.460 0 . 00 35150 . ' 9.39 374.39 266a25. 6.116 1.590 0. 00 35455 . 9.58 374.58 273191. 6.272 1.710 0. 00 35761. 9.78 374.78 280375. 6.437 1. 810 0. 00 36085 . 9.97 374 .97 287261. 6.595 1. 900 0. 00 36393 . i0.16 375.16 294205. 6.754 1.990 0. 00 36703. 10 .35 375.35 301208. 6.915 2 .070 0. 00 37014 . 10.55 375.55 308644. 7 .085 2 .150 0. 00 37342 . 10 .74 375.74 315768. 7.249 2 .230 0.00 37655. 10.93 375 .93 322953 . 7.414 2 .300 0. 00 37970. I 11.12 376. 12 330197. 7.580 2 .370 0.00 38285. 11.32 376.32 337887. 7.757 2.440 0.00 38619. � 11.35 376.35 339047. 7.783 2.450 0.00 38669. I 11.45 376.45 342922. 7.872 3.100 0. 00 38836. I 11.55 376.55 346814. 7.962 4.260 0. 00 39004 . 11.65 376.65 350723 . 8.051 5.750 0. 00 39172 . i1.75 376.75 354648. 8.142 7.510 0.00 39340. 11.85 376.85 358591. 8.232 9.500 0. 00 39509. 11.95 376.95 362550. 8.323 11.690 0. 00 39677 . 12 .05 377.05 366526. 8.414 14 .080 C .00 39847 . 12 .1� 377.15 3705I9. 8.506 16.230 O .00 400i6 . ' 12 .25 377.25 374529. 8.598 17 .080 0 . 00 40186 . �, 12 .35 377.35 378557. 8.690 17. 890 0 . 00 40356 . 12 .45 377.45 382601. 8.783 18 .660 0 .00 40527 . 1� . 5� 3� , .�� 3�5�5� . 8 . 8?� �9. 390 v . 0� =0E9 - =2 . 55 377. 55 39C�?��. 8 .970 2C . D90 O.00 �0869 . i2 .75 377.75 394836. 9.064 L0.770 G.00 4104C . 12 .85 377.65 398948 . 9.159 21.430 0.00 41212 . 12 .95 377.95 403C78 . 9.253 22 .060 0.00 41384 . 13 .05 378.05 407225 . 9.3�9 22 .680 O.00 41556. 13 .15 378.15 411389. 9.444 23 .280 O.00 4�729. � 13 .25 378.25 415571. 9.540 23 .860 O .00 4=902 . '� H�_�d �nflow Outflow Peak Storage I�i Target Calc Stage Elev {Cu-Ftj �Ac-r�) � 12 . 82 4.34 7.83 11.77 376.77 355284. 8 . 156 � 6.29 2 .42 2 .41 11.24 376_24 334808. 7.686 3 7.73 2 .42 1.95 10.08 375.08 291291. 6.687 4 7.58 2 .35 1.75 9.67 374.67 276402 . 6.345 5 6.67 2 .18 1.46 9.20 374.20 259668 . 5 .961 5 6 .43 0.72 0.69 7.32 372.32 196425 . 4 .509 ' ? 5 .02 ******* 0.62 5.89 370.89 152098. 3 .492 8 5.32 ******* 0.54 4.52 369.52 112288. 2 .578 � 3cute Time Series through Facility Lnflow Time Series File:dev.tsf Outflow Time Series File:rdout �aflow/Outflow Analysis Peak Inflow Discharge: 12.83 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 7.83 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 11.77 Ft Peak Reservoir Elev: 376. 77 Ft Peak Rese�✓oir Storage: 355284. Cu-Ft . 8.156 AC-Ft _ iow ^requer_cy Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----�low Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 2 .41 2 2/09/O1 20:00 7.83 11.77 1 100 .00 0. 990 0 . '0l8 7 12/28/O1 18:00 2.41 11.23 2 25 .00 0. 960 �.75 4 3/06/03 22 :00 1.95 10 .08 3 10.00 0 . 900 0 .�41 8 B/26/04 7:00 1.75 9.67 4 5.00 0. 800 0 . 689 6 1/05/05 18: 00 1.46 9.19 5 3 .00 0 .667 1.46 5 1/18/06 23 : 00 0.689 7.32 6 2 .00 0 .500 1. 95 3 11/24/06 8:00 0.618 5.89 7 1.30 0 .231 7. 83 1 1/09/08 10 :00 0.541 4 .52 8 1. 10 0. 091 Computed Peaks 6.02 11.67 �0. 00 0. 980 =1ow Duration from ^'ime Series File:rdout.tsf Cutoff Count Frequency CDF E;cceedence Probability C=S % � � O. C34 37910 61.823 61.823 38. 177 0 .382E+00 0 . 102 4292 6.999 68.823 31. 177 0.312E+00 C . 169 4500 7.339 76.161 23 . 839 0.238E+00 C .237 3823 6.235 82 .396 17.604 0 .176E+00 0 . 3C� 332� 5 .=19 9? . 315 '_� . "�25 � . =�?E+00 0.372 2468 4 .C25 91.840 8.i60 0 .816E-01 � 0 .440 1738 2 .834 94.674 5.326 0.533E-01 0 .507 1153 1.880 96.554 3 .446 0.345E-01 0 .575 7a7 1.218 97.772 2.228 0.223E-01 0.643 567 C .925 98.697 �.303 0 . 130E-01 0.710 472 0 .770 99.467 0 .533 0.533E-C2 0.778 174 0.284 99.750 0 .250 0.250E-02 0. 845 18 0.029 99.780 0 .220 0.220E-02 0. 913 16 0 .026 99.806 0.194 0.194E-02 ' 0.980 15 0.024 99.830 0.170 0 .170E-02 1. 05 6 0. 010 99.840 0.160 0.160E-02 1. 12 3 O. 005 99.845 0.155 0.155E-02 1.18 4 0.007 99. 852 0.148 0.148E-02 1.25 0 0.000 99.852 0.148 0.148E-02 1.32 3 0 .005 99.856 0.144 0.144E-02 1.39 3 0.005 99.861 0.139 0. 139E-02 1.45 15 0.024 99.886 O.I14 0.114E-02 1.52 8 0.013 99.899 0.101 0. 101E-02 1.59 6 0.010 99.909 0.091 0 . 913E-03 1.66 6 0.010 99.918 0.082 0. 815E-03 1.72 8 0.013 99_932 0.068 0 .685E-03 1.79 10 0_016 99. 948 0.052 0.522E-03 1_86 6 0.010 99. 958 0.042 0.424E-03 1.93 6 O.Q10 99.967 0.033 0.326E-03 1. 99 3 O.Q05 99.972 0.028 0.277E-03 2 . C6 2 O.0O3 99.976 0. 024 0.245E-03 2 . 13 3 0.005 99.980 0. 020 0 .196E-03 2 .20 1 0.002 99.982 0.018 0 .179E-03 2_26 3 0.005 99.987 0.013 0 .130E-03 2.33 3 0 .005 99.992 0.008 0. 8=5E-04 2 .40 4 0.007 99.998 0.002 0. 163E-04 �yd Inflow Outflow Peak Storage Target Calc 8tage Elev (Cu-Ft) {Ac-Ft) 1 12 .82 4.34 7.83 11.77 376 .77 35�284 . 8.156 2 6.29 2 .42 2 .41 11.24 376.24 334808 . 7.686 3 7.73 2 .42 1.95 10.08 375. 08 291291. 6.687 4 7.58 2 .35 1.75 9.67 374 . 67 276402 . 6.345 S 6.67 2 .18 1.46 9.20 374.20 259668 . 5. 961 6 6.43 0.72 0_69 7.32 372.32 196425 . 4.509 7 5.02 ******* 0.62 5.89 370 .89 152098. 3 .492 9 5 .32 ******* 0.54 4.52 369.52 112288 . 2.578 Duration Comparison Anaylsis Base File: predev.tsf New Fi�e: rdout.tsf Cutoff Units: Discharge in CFS -----Fraction cf Time ---------Check of Tolerance------- Cutoff Base New 3Change Probability Base Vew �Change 0 .719 � 0.65E-02 0.48E-02 -27.2 I 0.65E-02 0. 719 0 .693 -3 .6 0 .774 � 0.57E-02 0.25E-02 -56.4 � 0.57E-02 0.774 0 .706 -8.9 0. 829 I O.S1E-02 0.23E-02 -55.2 I 0.51E-02 0 . 829 0.714 -13 .8 0 . 884 I 0.45E-02 0 .20�-02 -54. 9 � 0.45E-02 0 . 884 0.723 -18.2 0 . 939 .' O .aOE-02 0.19E-02 -53 .4 � 0.40E-02 0 .939 0.731 -22.1 C . 993 ' 0 .35E-02 0 .17E-02 -52 . 8 I 0 .35F-02 0. 993 0.738 -25 .7 1. n5 0 . 31�-C2 � . l0'E-0? -48 . 1 I � . 3'_�-C� 1 .05 C . �5 -28 . _ i .10 I 0.2?E-02 O. lEE-02 -42 .9 � 0.27F-C2 1. 1C 0.753 -31. % 1.16 � 0 .22E-02 0. 15E-02 -33 .6 � 0 .22E-C2 1.16 0.843 -2; .� 1.21 I 0. 19E-02 0.15E-02 -22 .2 � 0. 19E-C2 1.21 0.925 -23 .� 1.27 � 0 . 17E-02 0.15E-02 -i1.8 I 0. 17E-02 1.27 0.997 -21.4 1.32 � 0. 15E-02 0.14E-02 -2 .2 I 0. 15E-02 1.32 1.30 -1 .6 1.38 I 0 . 13E-02 0.14E-02 10.1 I 0. 13E-02 1.38 1.43 3 .� 1.43 I 0 . 12E-02 0 .13E-02 8.5 I 0. 12E-02 1.43 1.45 l .c' 1.49 � 0.11E-02 0 .11E-02 4 .6 I 0. 11E-02 1.49 1.50 1 . 0 1.54 � 0.96E-03 0.96E-03 0.0 I 0.96E-03 1.54 1.55 0.2 1.60 � 0.86E-03 0.91E-03 5 .7 I 0.86E-03 1.60 1.64 2 . 6 1.65 � 0.73E-03 0.85E-03 15 .6 � 0.73E-03 1.65 1.70 2 . 9 1.71 I 0.68E-03 0.72E-03 4 . 8 � 0.68E-03 1.71 1.73 1. 5 1.76 � 0.62E-C3 0.60E-03 -2 .6 � 0.62E-03 1.76 1.76 -0.2 1.82 j 0.55E-03 0.47E-03 -14 .7 � 0.55E-03 1.82 1.77 -2 .5 1.87 : 0.51E-03 0.41E-03 -19.4 I 0.51E-03 1.87 1.81 -3 . 1 1.93 � 0.41E-03 0.34E-03 -16.0 � 0.41E-03 1.93 1.87 -2 .� 1. 98 : 0.33E-03 0.28E-03 -15.0 � 0.33E-03 1.98 1.94 -1. 9 2.03 ; 0.29E-03 0.24E-03 -16.7 I 0.29E-03 2.03 1.97 -3 .0 2.09 i 0.23E-03 0.23E-03 0.0 � 0.23E-03 2.09 2.12 1.3 2 . 14 � 0.16E-03 0.20E-03 20.0 I 0.16E-03 2.14 2.23 3 .8 2.20 I 0.98E-04 0.18E-03 83 .3 � 0.98E-04 2.20 2 .33 5 .8 2.25 I 0.98E-04 0.15E-03 50.0 � 0.98E-04 2.25 2 .33 3 .2 2.31 � 0.98E-04 0.98E-04 0.0 I 0.98E-04 2 .31 2 .33 0. 7 2.36 � 0.82E-04 0.65E-04 -20.0 ' 0.82E-04 2 .36 2 .34 -1.2 2.42 � 0.33E-04 O.00E+00 -100.0 ; 0.33E-04 2 .42 2 .40 -0. 8 Maximum positive excursion = 0.140 cfs ( 6 .40) occuring at 2 . 19 cfs on the Base Data:predev.taf and at 2 .33 cfs on �he New Data:rdout.tsf Maximum negative excursion = 0.358 cfs (-32 .0%) occuring at 1 . 12 cfs on the Base Data:predev.tsf and at 0. 759 cfs on the New Data:rdout.tsf Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft; (Ac-Fti 1 12 .82 4 .34 7.83 11.77 376.77 355284 . 8.156 2 6 .29 2 .42 2 .41 11.24 376.24 334808 . 7 .686 3 7.73 2 .42 1.95 10.68 375.08 291291. 6.68i 4 7.58 2 .35 1.75 9.67 374 .67 276402 . 6.3=5 5 6.67 2 . 18 1.46 9.2C 374 .20 259668 . 5. 961 6 6.43 0.72 0.69 7.32 372 .32 196425 . 4.509 7 5.02 ******* 0.62 5 .89 370.89 152098 . 3 .492 8 5 .32 ******* 0.54 4 .52 369. 52 112288 . 2 .5?fi PREDEV.PKS Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 2.42 2 2/09/Ol 15:00 4.34 1 100.00 0.990 1.34 7 1/05/02 16:00 2.42 2 25.00 0.960 2.42 3 2/27/03 7:00 2.42 3 10.00 0.900 0.941 8 8/26/04 2:00 2.35 4 5.00 0.800 1.43 6 1/05/05 8:00 2.18 5 3.00 0.667 2.35 4 1/18/06 16:00 1.43 6 2.00 0. 500 2.18 5 11/24/06 4:00 1.34 7 1.30 0.231 4. 34 1 1/09/08 6:00 0.941 8 1. 10 0.091 Computed Peaks 3 .70 50.00 0.980 Page 1