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Home My WebLink About03012 - Technical Information Report - Drainage - - ^ 4205 148th Ave.N.E.Suite 100 I��I / \ CORE Bellewe,Washington 98007 i 425.885.7877 Fax 425.885.7963 \ /DESIGN `/ I�,1 �•m ( ��f ' ��--'��i o~' - - �� Jl� �� . ��" `A MY _'• STORM DRAINAGE CALCULATIONS FOR PETERSEN PARCEL RENTON,WASHINGTON \ ��Y ��j�.� .� ,� - jf, ��' -, i r�}. :�1 1 e .� J � i f)� "�,'� . � 3:�;13 .s..� I C3\ E'U,�,.r �`� . `s' ' Prepared by: Gina R Brooks,P.E. � -"°�' �,��' ��c�rqa�.�� Approved by: David E. Cayton,P.E. _ - �11� Date: April 12,2002 L��—�� ' Core No.: 01024 TLe��ed= 5��.. ?. Zdoz � I'I � 3d1� ENGINEERING • PLANNING • SURVEYING �il PETERSEN PARCEL TABLE OF CONTENTS - 1. Project Overview 2. Off-Site Analysis 3. Flow Control and Water Quality Facility Analysis and Design 4. Conveyance System Analysis and Design 5. Erosion Control Calculations 1. PROJECT OVERVIEW: The Petersen Parcel is located at 14639 SE 132nd Street(NE 2"d Street) in Renton, Washington. See attached vicinity map. The 2.15 acre site is currently occupied by one single family residence. The existing ground cover is grass. T'he developer proposes to construct 6 single family residences with associated roadway and utilities. The existing house will remain and will be delineated as a separate lot. Half-street improvements will be completed along SE 132"� Street as part of this project. The City of Renton requires Leve12 Flow Control and Basic Water Quality for the site. The developed runoff will be directed to a combination water quality/detention pond. The wetpond will discharge to the existing wetland located at the south end of the property. II ; i . I , � . 405 5 4 3 2 QA-�' �`�jP�� o0 � r 8 9 10 � 11 N RENTON a� ( � � NE 4n� sr. � izBTM sr. �NE�� 5�, BM PT. pN p , ) t852 2]03 GIiE�IW00D CEhIElERY 1 169 16 1 14 '�F ` �AR � � MAPlEWUOD GOLF COURSE YICINIT�' 1"1,4i� � N �� . 3000�t _ _ ' � - � i - ---��.-' . � { ..\ / _�` ` : , �`� �."'��' ! i � a `�� r `� i .� �ti :a/�� . . 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'� , I � �D � � � 3 I '`� _��`' �� as �\ r ` xeRi73 � \�`. \` �� p x:33.2f f� i�`�� .�: • � ! �`� L.CSI � /` • ' x E r � � t j �....�_.� � --- i � 'Is � `� I ( � �. � �� 1 1 \ ''t f � a�� ', `', r�� a[� x''�s"�.4 � �l '. �'�.:' ,--'�' '� r t �,�,� , � , ` +. �v�S f' x:z4Ta :` `.� s� �_ i �c Xmei .-� '•r�f\`! I� ` ,� � [ � �rp �� be �� A�3a'°s �t f� i2,�< � 1 ! 1'FT� � , � �m► Y f .. � � .._ _ , a , • � �—�`, ,, >� c�' . - 1 , --- �,'� rsa+ i? �'-� `'t ,��' � f ' �, �% a't �� .` `\ x „-''Tzvf.c �`. I :��j `� i` i � i ;i t, � \ � �-M c r \ i l !I . � ; r' \ '� `��.. �'"`�� ,as.rs ,��.e� �� _ ",:,.ae j ,, � 3 ; ! , � " ; x uas. �� / i ; �.'� 4 i �!J9 ,am,s7 tZs.'N X:�35 R _ '( y; _ i ; � ��.�� ; i - � > `� -��"~ -- � � �9 X I �'____..,'" ...--' .�__�' �t ; �t _,�-- t�� . �� . �t� �� _ �"� i ! :1 � �� + ,`t D4 .,- , � ��x�._�r � r .�J ' F ; : �{ �; _�� . i . / \�J , i t �"`�.._,_,� ,�' 's, i 1, t, � r� ; ,� � �� " ��r :<- �;, � � • , DOWNSTREAM MAP � "� � `h t '� y PETERSEN PARCEL ` -�`-� -'' �ff ''.. -- -__----_ .�.��f' %i�� ,,� a C ORE NO. 01024 :.. __ ,��`�.--� . `��.�^ �j �� ! - � _�` - - �. � _ 1 vig.� �� . ' � . . . _ - 3. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND I DESIGN: A. Hydraulic Analysis The drainage analysis was modeled using the King County Runoff Time Series soflware. The soils are Indianola(AgC}, KCRTS group Till. T'he site is located in the Sea-Tac rainfall region with a location scale factor of 1.0. EXISTING CONDITIONS The site is 1.73 acres. Of the 1.73 acres, 0.11 acre was included as part of the site along a portion of the frontage along�1E 2"� Street from the north property line to the crown of the road since half-street improvements will be constructed as part of the project. Drainage will be captured only along a portion of the frontage. The existing asphalt area that will be collected via the frontage catch basin system will be analyzed as pervious area in the existi�g conditions for the purpose of compensating for the new impervious area that will not be captured within the proposed storm drainage system. A single a residence cunently occupies the site. The impervious area associated with the single residence on the site covers an area of 0.25 acre. The existing pervious ground cover is till-gras�. The following information was used for generating time series and flow frequencies. I EXISTING CONDITIONS Total Area= 1.73 acres (1024ex) GROUND COVER AREA(acre) Till-Grass 1.48 Impervious 0.25 ,_.�_._�.. .��,,.�.z,..... , mc 198AGfJAH-s�wr. 10� 1 680000 FEET 122�07'30" , s _ , 47°�^� _ � 7�� . . , _ i AgD. r 9 ' ; � . . .... • . •n . � �� 1� , _• ��• a � � �1 -• ' • _i , �� . . I . a 3 � AmC i • '•'� 1 1 � a H � I S o. � �. � 1 q h . � T .�= 1 t' � y 'ry il � �S��i �%� i ' • o � , "ABC• . � t�.-. �� . � ' i •. � ' �...... . . . I -� , 1 C� ' .. �-' i �9 , '•413 ��1.� �gw�•935 _ � II `� �vl�.� � - a �i \ •- � � � � � -; '� j _ ; p • = I ti�.��% r � . .. = BB ��• �0 I •'� �` • ��_- -- P�� . ; - -- } .. � � , ti'- _ • �1 • -� An , , e . . „ -= ____ _ �f 3� KQtTSJRUNOF'F'FiLE E'i'HOD—GENERATIIVG TIMF SERJES _ _ . � . .. . � :T�iIiT.:E� �� :�QUIVAI.�NC'E i3E�'WEEN:SCS:SOII.TYPES.�,ND'�C�tTS SOII,TypES SCS Soil Type SCS KCATS Sail Notes Hydrologic Group Soil GrQup e oo ABACAD C � Arents,Alderwood Matenai(AmB,AmC) C Till Arerrts, Evereit Material (An) B Outwash - 1 Beausite (BeC, BeD, 8eF} C Till 2 Bellingham{Bh) D Tili 3 Briscot (BF) D ' Tfi 3 Bucldey (Bu) D Tili 4 Earimont(Ea) D Till 3 . Ed ewicic (E� C Tiil 3 Everett(EvB, EvC, EvD, EwC) A/B �utwash 1 Indianola(InC, 1nA, InD) . A Outwash 1 1�Ctsa� ( 6,KpC, I(P�) C Till Klaus(KsC) C �utHrash 1 Neilton (NeC) A Outwash 1 Newbe (N ) B Tiq 3 Nooksacic (Nk) C Till 3 Norma (Na) D Till 3 Orcas (Or) D We#land Oridia (Os) � D Till 3 Ovall (OvC, �rr0,OvF� C Till 2 Pi�hucic (Pc) C Tii! 3 ' Pu et(Pu) D Till 3 puyaiiup (py) � B Tiil 3 Ra nar(RaC, RaD, RaC, Ra� 8 Oulwash 1 , Renton (Re) D Till 3 ' Salal Sa) C Till 3 Samrnamish (Sh) D T�1 3 Seattie (Sk) D Wetland Shalcar(Sm) D Ts7! 3 Si(Sn) C Tiil 3 Snohomish (So, Sr� D Tiii 3 Sultan (Su) C Tiil 3 Tuicwiia u) D Till 3 � Woodirnrille(Wo) D TiQ 3 Note� � 1. Where outwash sais are sattuated or underiain at shallow depth(<5 feet)by glaaal�11,they shoutd be Veated as t�f sais. 2. These are bedrodc sa�s, but ca6bration of HSPF by King Cow�iy DNR shows bedrock scils t�ha�a sim�ar hydrologic respoose to tgi sails. 3. These are alluvial soils,some of which are underisin by giaaai tlll or have a seasonalty high water table. In the absence of detaiied study, these saiis shuuld be treated as til1 soils. . 4. Buddey soiis are formed on the low-permeabifiiy Oscaola mudflow. Hydrologic response is assumed to be simitar to that of til!soiis. t998 Surfaca WaurDesign Maaua! 9/1198 3-ZS � S�' 1.01 ' ST 1.0 L,� 0.9 Ld4 1• � 1.� �� .� . � O�� SNO�YIBN COUMTY � �N�W ' 71IOo01NV1[L6 1�tio e�sv�' �� : ., s �-. _ �wn coq:�€r : ,� �":\�� i y -1 � __.-,�� ., /�'� t ��9M /y ��(T � '� ..:^ �r: . � / l� �i� kL � '• �_.�-�� : § .,. . _i` _ :js' < I -•--.%�_ S t�V4l1� - - - _ � .. � `1 � �",$� , f, � � ��:�✓ i � i � �f � - E� 5 �` �' ,r ' --i� �,..i l' - - ' � :; ��,y� � ' � � � �� ,5 . - 'rr' �" �� ' .✓�� 'f ,��-�5 s`��}, �1 �.�� a' ,�• , � < . g� _ – � _ _ ` E''� r �,�,� '� t� �`;R NB%�, ��`^ _ f � _ � y' �, �, , , � i �;> .�-� y �''�, ��` f' -�'�J'�`• � '�,, _ � - . . _. �,r� ' �,. �I . ...r �_. � -L., .� � �'l � ,,� j�:� i.: '' _I� :: I . ' �;,N- � l � > - �' ' v:: ^. 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T�..a ,� ,��•. ��_ -.a � . — �f7� r U�= T`�' ,.I �;'. ,��s - '� �_F�"`��•�i��.. ..7r _ - _.�--�. :-� � - - _ .`� .-� ` .. oHOHAN 4��—� �- � �'� �� 1� EflGErl. � � \ � � �. . �} >�I .r �w;�o:� 2.:.�" �,\��,. r „-. �� - � - ' � �] � . . ��- �y � .��E}��j' `� � � ' `~l '� ��/ '� �J� r� - ` �,,,�.,n,.t�f � - � � i � t " - =� - - .,}\..� ,/ . , a-�� t�: aES•Cft �j"�WSLM . �. �� y r � � !�` � , ' � 4E��— ��` .,f I' -PIIllli6 Y��¢ " ,t�, � � � �/ t + ��_r�� 2 4 � ;�� ;�,. :.YFaEN, � �� ... � � � J y� " . - ' �. :mIB4YON �� r t. y �� _. :': r . , ,�. � EN7G� ' � . . i:. . � �'` ;. . � `,�° .' 7 % — f: �' . � '� .p� , , 1 r' .� �'� .> > �, -.�. � " -. � ��: � .�'..� _� GPYGNT ' . � _ i/�I�YI� 3 �I �� KEflNS:O[E' � ' - ��, , � ; � � __ , f� =. _ �� L�6�E�S��d�.� - , . � � : ,��. -� I � _�� ;� vaMw r � a� nnove' � - � I�IW - .�! �- � � ��.�� - ✓'� i / - / . Q�_. �.f` ' y f_ � � � . J,i. �_, '� �,�,��'1 v �� uwmgupp� .. ' 1_ . �r �'�: � �. ` ui� _ � . . " � ''�-•y � "t =r = G,�E-� "�. "t i'� �� '� � ' � -�. +�,. 1 �j1a �l � �� j � � � _ .� ��i �� „f� , � �s� /��r�'\ � t `� � �'� � : �' ,1 i. .:''j� �f- .`� � ,��Ti«, �c . -� - ./, ,ywin .� P4vadn r ' 1—� ST 1.1 � B� ; � ' �,r =-; Y� - € � t : , ��, �; �_ s -� �� g� � � � �� . �,+'�1 � � � � � anr.� ��. �" y1rCsQLLNTJ/' � � _ � _ a� � PllHCQ COUNTY _ _ .� \ - - ST 1.0 �, �� - . � - "1�,�� - _ S71.0/ � `�-� Rainfali Regions and �A o.s -�' ' i �- � -� _ Regionai Scale Factors �a o.9 `�T� ��3� - ��f - LA 1.2 � Incorporated Area � �'� �.� River/Lake Major Road Flow Frequency Analysis Time Series File:1024ex.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 0.193 4 2/09/O1 2:00 0.431 1 100.00 0.990 0.121 6 1/05/02 16:00 0.240 2 25.00 0.960 0.240 2 2/27/03 7:00 0.200 3 10.00 0.900 0.090 8 8/26/04 2:00 0.193 4 5.00 0.800 0.118 7 10/28/04 16:00 0.184 5 3 .00 0.667 0.200 3 1/18/06 16:00 0.121 6 2.00 0.500 0.184 5 11/24/06 3:00 0.118 7 1.30 0.231 0.431 1 1/09/08 6:00 0.090 8 1.10 0.091 Computed Peaks 0.367 50.00 0.980 DEVELOPED CONDITIONS The developed site will consist of 7 single family residences, 6 new and 1 existing, with associated roadway and utilities. The impervious area was calculated using the criteria in the 1998 I�ing County Surface Water Design Manual page 3-27 and K.C.C.21A.12.030. The maximum impervious coverage per lot is assumed to be either equivalent to the amount as calculated using m�imum percentage of impervious surface coverage or a maximum of 4,000 square feet per lot whichever is less. The site is R-5 zoning. Since there is no information in K.C.C.21A.12.030 for R-5 zoning, the maximum impervious coverage was interpolated between R-4 and R-6. The maximum impervious surface per lot is interpolated to be 62.5%. All other impervious surfaces were measured by a planimeter. The srnallest lot on the site measures 7,202 square feet. The m�imum impervious area is therefore 7202*62.5%=4,501 square feet. Since this is larger than 4,000 square feet, 4,000 square feet for each lot was assumed for the impervious coverage. Impervious Area Delineation SE 132 Street 4,716 sf Existing Residence 10,890 sf Impervious area of lots (61ots*4,000 s� 24,000 sf Access Road 5,346 sf Total impervious area 44,952 (1.03 acre) The input used for the KCRTS analysis is summarized in the table below: DEVELOPED CONDITIONS Total Area= 1.73 acre (1024d) GROUND COVER AREA(acre) Till-Grass 0.70 Impervious 1.03 . . 21 A.12.030 A. Densities and dimensions - residentia! zones .`:z RESIDENTIAL z nWu� uw�r um+�r o ' N N�VE IESpBrTUL H S sra�c�s wass w►a w►-�o �u►-m u� �.� �.s x� ie-e �u a.�a e-ta �e n� mr.onr�qr• at os a� aos oa t s � e u u sa a o.��aq arrae duac auae aua�e arae auae d�ae a�we durac a�we duae mrae auru �+�+� {�1 Nl Hsl �n� a.� aa s a u ts v x n . �v� arre �ac auae auae daae duae auae a�,ae aaae n� ao► ao� � �dnY�OrwH: a6% fl7L B57L LOX 75% 70% iB% � n� n� n�a rn ra� a� n•� c+n r�n rn � ■.rsua toc �u e ws e ��rt tiss e aa a aa rt ao ee �n ao a �o a amt ao a �o a +� m m a� I F_� rO�""$°�'t �e aee �oa �oa mA aoe toa tote �os �om m� �at toa I s"bik c� a� � � m m c•► m �i m m � m m IioYM�Y�tlor SR 70R 1�1t 1�1t 5R. iR 6Q bR 5A Stt 5R 7tt SR s«e.a� � � �.► � m m ��o� c�� rei c+o� r��+h Bap Htlpht M R �01! �0 R q tt 35 R M R 36 R 36 R �5 R i0 R f0 R BO h i01! Nl IiR (SR /OR !OE �OR �+q r� n+� n•� ns� � �sx m�c ,.x ,asx �ox nox eex 7ox rsx asx ,sx sa�c wu mvn�• n,i n,� a,� r�� n+� c+�t 9� c�► c+s� rn m� �ane+w(� � .� (pa�5�o � � 12-2 (Kirig County 6-00) Flow Frequency Analysis Time Series File:1024d.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 0.312 6 2/09/O1 2:00 0.635 1 100.00 0.990 0.252 8 1/05/02 16:00 0.392 2 25.00 0.960 0.376 3 2/27/03 7:00 0.376 3 10.00 4.900 0.269 7 8/26/04 2:0a 0.331 4 5.00 0.800 0.325 5 10/28/04 16:00 0.325 5 3.0a 0.667 0.331 4 1/18/06 16:00 0.312 6 2.00 0.500 0.392 2 10/26/06 0:00 0.269 7 1.30 0.231 0.635 1 1/09/08 6:00 0.252 8 1.10 0. 091 Computed Peaks 0.554 50.00 o.980 , B. Detention Routing Calculations The City of Renton requires Leve12 Flow Control for the subject �ite. The proposed wetpond will be a combination water quality and detention pond. The live portion within the pond will accommodate the required detention volume. See attached Pond Volume Calculations excel spreadsheet for stage-storage values for the pond to be constructed. � Also, see attached KCRTS printouts. The proposed pond to be constructed exceeds the minimum required storage as calculated for the KCRTS pond therefare, the proposed pond will function better than that pond created by KCRTS. The proposed pond is therefore, adequate for the subject site. Stormwater flows in excess of the capacity of the control structure riser will overflow through an emergency overflow route that was established by design of a spillway lined with riprap that will direct runoff into the existing wetland. The primary overflow elevation is EL 418.50 (shown as design maximum water surface on the plans). The secondary overflow flow elevation is EL 418.60 (shown as overflow elevation on the plans)which will also be the top of the riprap of the emergency overflow spillway. The required spillway length is calculated per KCSWDM section 5.3.1.2 as follows: Emergency Spillway Calculations Ql�=0.635 cfs (peak inflow to pond), Assume H=0.2'(minimum value) L = (Q,o�/(3.21H3'z)) - (2.4I-�_ (0.635/(3.21(0.2)3�z)) - (2.4(0.2)) = 1.73' (Use 6' min.) POND VOLUME CALCULATIONS CORE PROJECT NO. 01024 PROJECT NAME: PETERSEN PARCEL LEVATIO SURFACE SURFACE INCREMENT TOTAL LNE AREA AREA VOLUME VOLUME VOLUM SI SF CF CF CF 411.0 1.09 436 0 556 412.0 1.69 676 556 0 412.0 2.42 968 556 3,004 414.0 5.09 2036 3,560 0 414.0 5.72 2288 3,560 2,590 415.0 7.23 2892 6,150 0 3,156 416.0 8.55 3420 9,306 3,156 8,040 418.0 11.55 4620 17,346 11,196 Retention/Detention Facility Type of Facility: Detention Pond Side Slope: 3.00 H:1V Pond Bottom Length: 56.00 ft Pond Bottom Width: 33.00 ft Pond Bottom Area: 1848. sq. ft Top Area at 1 ft. FB: 4560. sq. ft 0.105 acres Effective Storage Depth: 3.00 ft Stage 0 Elevation: 415.00 ft Storage Volume: 8271. cu. ft 0.190 ac-ft Riser Head: 3.00 ft , Riser Diameter: 12.00 inches � Number of orifices: 2 Full xead Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 1.30 0.079 2 2.00 1.25 0.042 4.0 Top Notch Weir: Rectangular Length: 1.00 in Weir Height: 2.40 ft Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area II (ft) (ft) (cu. ft? (ac-ft) (cfs) (cfs? (sq. ft) 0.00 415.00 0. 0.000 0.000 0.00 1848. , 0.01 415.01 19. 0.000 0.005 0.00 1853 . , 0.03 415.03 56. 0.001 0.008 0.00 1864. 0.04 415.04 74. 0.002 0.009 0.00 1869. 0.05 415.05 93. 0.002 0.011 0.00 1875. 0.07 415.07 131. 0.003 0.012 0.00 1886. 0.08 415.08 150. 0.003 0.013 0.00 1891. 0.09 415.09 169. 0.004 0.014 0.00 1896. 0.11 415.11 207. 0.005 0.015 0.00 1907. 0.21 415.21 400. 0.009 0.021 0.00 1962. 0.31 415.31 599. 0.014 0.025 0.00 2017. 0.41 415.41 803. 0.018 0.029 0.00 2073. 0.51 415.51 1014. 0.023 0.033 0.00 2130. 0.61 415.61 1229. 0.028 0.036 0.00 2187. 0.71 415.71 1451. 0.033 0.039 0.00 2245. 0.81 415.81 1678. 0.039 0.041 0.00 2304. 0.91 415.91 1912. 0.044 0.044 0.00 2364. 1.01 416.01 2151. 0.049 0.046 0.00 2424. 1.11 416.11 2397. 0.055 0.048 0.00 2485. 1.21 416.21 2648. 0.061 0.050 0.00 2547. 1.31 416.31 2906. 0.067 0.052 0.00 2609. 1.41 416.41 3170. 0.073 0.054 0.00 2673 . 1.51 416.51 3441. 0.079 0.056 0.00 2736. 1.61 416.61 3718. 0.085 0.058 0.00 2801. 1.71 416.71 4001. 0.092 0.060 0.00 2866. 1.81 416.81 4291. 0.099 0.062 0.00 2932. 1.91 416.91 4587. 0.105 0.063 0.00 2999. 2.00 417.00 4860. 0.112 0.065 0.00 3060. 2.01 417.01 4891. 0.112 0.065 0.00 3067. 2.03 417.03 4952. 0.114 0.066 0..00 3080. 2.04 417.04 4983. 0.114 0.068 0.00 3087. 2.05 417.05 5014. 0.115 0.071 0.00 3094. 2.07 417.07 5076. 0.117 0.074 0.00 3108. 2.08 417.08 5107. 0.117 0.078 0.00 3114. 2.09 417.09 5138. 0.118 0.079 0.00 3121. 2.10 417.10 5169. 0.119 0.080 Q.00 3128. 2_12 417.12 5232. 0.120 0.081 0.00 3142. 2.22 417.22 5550. 0.127 0.088 0.00 3211. 2.32 417.32 5874. 0.135 0.094 0.0� 3281. 2.40 417.40 6139. 0.141 0.098 0.00 3337. 2.48 417.48 6408. 0.147 0.106 0.00 3394. 2.55 417.55 6648. 0.153 Q.115 0.00 3444. 2.63 417.63 6925. 0.159 0.125 0.00 3501. 2.70 417.70 7172. 0.165 0.138 0.00 3552. 2.78 417.78 7459. 0.171 0.152 0.00 3611. 2.85 417.85 7713. 0.177 0.167 0.00 3662. 2.93 417.93 8009. 0.184 0.183 0.00 3722. 3 .00 418.00 8271. 0.190 0.200 a.00 3774. 3 .10 418.10 8652. 0.199 Q.511 0.00 3849. 3 .20 418.20 9041. 0.208 1.080 0.00 3925. 3 .30 418.30 9437. 0.217 1.810 0.00 4002. 3.40 418.40 9841. 0.226 2.600 0.00 4080. 3.50 418.50 10253. 0.235 2.890 0.00 4158. 3.60 418.60 10673. 0.245 3 .150 0.00 4237. 3.70 418.70 11101. 0.255 3 .390 0.00 4317. 3 .80 418.80 11536. 0.265 3.610 0.00 4397. 3 .9U 418.90 11980. 0.275 3.820 0.00 4478. 4.00 419.00 12432. 0.285 4.010 0.00 4560. 4.10 419.10 12892. 0.296 4.200 0.00 4643. 4.20 419.20 13361. 0.307 4.380 0.00 4726. 4.30 419.30 13837. 0.318 4.550 0.00 4810. 4.40 419.40 14323 . 0.329 4.720 O.OQ 4895. 4.50 419.50 14816. 0.340 4.870 O.OQ 4980. 4.60 419.60 15319. 0.352 5.030 O.Oa 5066. 4.70 419.70 15830. 0.363 5.180 O.UO 5153. 4.80 419.80 16349. 0.375 5.320 0.00 5241. 4.90 419.90 16878. 0.387 5.470 0.00 5329. 5.00 420.00 17415. 0.400 5.600 0.00 5418. Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 0.63 ******* 0.54 3.10 418.10 8669. 0.199 2 0.31 0.24 0.22 3.01 418.01 8290. 0.190 3 0.33 ******* 0.18 2.91 417.91 7917. 0.182 4 0.31 ******* 0.19 2.96 417.96 8116. 0.186 5 0.38 ******* 0.13 2.66 417.66 7022. 0.161 6 0.20 ******* 0.09 2.23 417.23 5579. 0.128 7 0.25 ******* 0.05 1.45 416.45 3290. 0. 076 8 0.27 ******* 0.05 1.33 416 .33 2955. 0 . 068 ---------------------------------- Route Time Series through Facility Inflow Time Series File:1024d.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 0.635 CFS at 6:00 on-Jan - 9 in Year 8 Peak Outflow Discharge: 0.536 CFS at 9:00 on Jan 9 in Year 8 Peak Reservoir Stage: 3.10 Ft Peak Reservoir Elev: 418.10 Ft Peak Reservoir Storage: 8669. Cu-Ft . 0.199 Ac-Ft Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS � $ � 0.003 46852 76.406 76.406 23 .594 0.236l3+00 0.009 4052 6.608 83 .014 16.986 0.170E+00 0.015 2871 4.682 87.696 12.304 0.123E+00 0.021 2183 3.56a 91.256 8.744 0.874E-01 0.027 1820 2.968 94.224 5.776 0.578E-01 0.033 1175 1.916 96.140 3.860 0.386E-01 0.039 823 1.342 97.482 2.518 0.252E-01 0.045 584 0.952 98.434 1.566 0.157E-01 0.051 402 0.656 99.090 0.910 0.910E-02 0.057 180 0.294 99.384 0.616 0.616E-02 0.063 158 0.258 99.641 0.359 0.359E-02 0.070 50 0.082 99.723 0.277 0.277E-02 0.076 10 0.016 99.739 0.261 0.261E-02 0.082 24 0.039 99.778 0.222 0.222E-02 0.088 26 Q.042 99.821 0.179 0.179E-02 0.094 30 0.049 99.870 0.130 0.130E-02 0.100 18 0.029 99.899 0.101 O.101E-02 0.106 7 0.011 99.910 0.090 0.897E-03 0.112 3 0.005 99.915 0.085 0.848B-03 0.118 7 0.011 99.927 0.073 0.734E-03 0.124 4 0.007 99.933 0.067 0.669E-03 0.130 7 0.011 99.945 0.055 0.554E-03 0.136 3 0.005 99.949 0.051 0.506E-03 0.142 2 0.003 99.953 0.047 0.473E-03 0.148 4 0.007 99.959 0.041 0.408E-03 0.154 4 0.007 99.966 0.034 0.342E-03 0.160 4 0.007 99.972 0.028 0.277E-03 0.166 3 0.005 99.977 0.023 0.228E-03 0.172 1 0.002 99.979 0.021 0.212E-03 0.178 4 0.007 99.985 0.015 0.1475-03 0.184 2 0.003 99.989 0.011 0.1145-03 0.190 4 0.007 99.995 0.005 0.4895-04 0.196 1 0.002 99.997 0.003 0.326E-04 0.202 0 0.000 99.997 0.003 0.326Fs-04 0.209 1 0.002 99.998 0.002 0.163E-04 0.215 0 0.000 99.998 0.002 0.163Fs-04 Duration Comparison Anaylsis Base File: 1024ex.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New �Change Probability Base New �Change 0.061 I 0.48E-02 0.47E-02 -0.7 � 0.48E-02 0.061 0.061 -0.2 0.075 � 0.29E-02 0.27E-02 -7.4 � 0.29E-02 0.075 0.067 -10.2 0. 089 � 0.19E-02 0.17E-02 -7.0 � 0.19E-02 0.089 0.087 -1.9 0.102 � 0.13E-02 0.98E-03 . -25.0 � 0.13E-02 0.102 0.094 -8.4 0.116 � 0.91E-03 O.SOE-03 -12.5 � 0.91E-03 0.116 0.105 -9.3 0.130 � 0.57E-03 0.55E-03 -2.9 � 0.57E-03 0.130 0.130 -0.3 0.144 � 0.34E-03 0.44E-03 28.6 � 0.34E-03 0.144 0.155 7.8 0.158 � 0.29E-03 0.29E-03 0.0 � 0.29E-03 0.158 0.158 0.0 0.171 � 0.16E-03 0.21E-03 30.0 � 0.16E-03 0.171 0.178 3 .8 0.185 � 0.98E-04 0.11E-03 16.7 � 0.98E-04 0.185 0.186 0.2 0.199 � 0.65E-04 0.33E-04 -50.a � 0.65E-04 0.199 0.190 -4.8 0.213 � 0.33E-04 0.16E-04 -50.0 � 0.33E-04 0.213 0.203 -4.5 0.227 � 0.16E-04 O.00E+00 -100.0 � 0.16E-04 0.227 0 .216 -5.0 Maximum positive excursion = 0.012 cfs ( 8.4�) occuring at 0.144 cfs on the Base Data:1024ex.tsf and at 0.156 cfs on the New Data:rdout.tsf Maximum negative excursion = 0.014 cfs (-12.7%) occuring at 0.112 cfs on the Base Data:1024ex.tsf and at 0.098 cfs on the New Data:rdout.tsf C. Water Quality Volume Calculations The City of Renton requires Basic Water Quality Treatment for the subject site. The proposed wetpond will be a combination water quality and detention pond. The dead portion within the pond will accommodate the required water quality volume. The dead storage for the pond was sized according to Section 6.4.1.1 of the 1998 KCSWDM. The following variables were used in the calculation: Volume Factor(fl= 3 Rainfall = 0.039 feet or 0.47 inches Area=upstream tributary area and developed basin Where A;= area of impervious surface (s fl A�= area of till soil covered with grass (s fl A�= area of till soil covered with forest(s fl Ao= ar�a of outwash soil covered with grass or forest(s� Vb=f*[0.9Ai+ 0.25Atg+ O.IA�+ O.OlAo] x(R/12) Vb= 3*[(0.9)(1.03) +(0.25)(0.70)]0.039 x (43560sf/ac) = 5,616 CF The proposed pond will carry a total dead storage volume of 6,150 CF which exceeds the minimum required 5,616 CF. See attached Pond Volume Calculations excel spreadsheet for stage-storage values for the pond to be constructed in Section 3B of this report. Approximately 1601ineal feet of NE 2°d Street will not be routed through the detention/water quality facility, see discussion in Section 3 of this report. In the existing conditions, approximately 3,000 SF of pollution-generating impervious surface drains west without water quality enhancement. This development include a storm drainage design were approximately 2,560 SF of pollution-generating impervious surface drains west without water quality enhancement, or approximately 15% less than in the existing conditions. Therefor, this develop is providing a greater level of water quality enhancement than currently provided. 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CB3 ,- . _ .. -.. } _ ; �ara�As.Q,ww _ - - �,,._�� 1 _ - nr�i w/sz�caa+zic cm . ..,- : , ,ew��.acn -- �ra��,sm . __ . NE 2°d STREET POLLUTION-GENERATING _ IMPERYIOUS SURFACES BASIN MAP _ -<_, ._ _ . ___ .__.___. � PETERSEN PARCEL CORE NO. 01024 _ 6.4.I WE'IPONDS—BASI iVD LARGE—METNODS OF ANALYSIS , - FIGiJRE 6.4.i.A PRECIPTTATION FOR MEAN A1�INUAL STORM IN INCHES (FEET� ST 1.0/ � 1 2 5T 1.1 , ST 1.0 I,p� 0.8 LA. 0.9 I`p` 1'� _ y �� _- 1- t _ 4 ..�z �..., r! t r� ' �'� —�, — `I - �,= —' t.x:�. _ :'� ��. ��`y i C %� L. _ _ �.. `�'.� Ti'Y° ��i �l :- R .._/ $,V � � :1 ` ' � �•- .x.�.A f+W � V. O �4..,f .� � \ �• � � `l � � i;✓ �� ' '. �± .'"ii .� -,�"�-^'�ti �f-- � � 1 -�r� �� '- T 3 :i�—� =5 i j `li.v� �i.' I-, R � _ � � -�.�� e � � ��`;. . �` ; ��"�Q� � � •�� ;,r � (f s :`-�- �,r.�'� ;�, ; ,! � ` • "�. � � s= .�-�-- l I �' g�� * �:<�$,-� . • �r - ' � � .s.�, ; , i� �`` � �.:;: . _ • �, .. . � � r ,_ � �,� � �� , ,� 'a � � . :/ � �• .� �j � �:, r/, � " ti�,hr�"_ �i• �i� � ..� � �'t� . r ` `y ,, �'.`� � "�„'r ��-�� - r I t� =� �--�� 1 � `1 - �i, y - ' �`. i �'.�.,,V'�- ,,,\ -' �,i;' _ �� s�' _ . �'� j s •., �� .Y� � . �.�. � \ %� ,i '� ��c� �: .r� i^ '� I �.:: r' . ti ai .'" . j �`� .-t s-" � F� C. k:i" i` ��< —._ �J; ' �' n^. _ j aa 'v� , , . �o ;. / � �� ,f-'-� i � , ,-r'-`"~ ��\ ' � � ,�.� ✓ X '�� . ?`. ...-r ,�._. ,� / '� .,.<, ` _�,� ,f � ��e Q :� - _ ; � � � � \ 0 _ � :`� j� _ / , '�9 ��—�• �, �;:. .. .,Soad Q ' _ . ; :�:.'J rt�i �3 .iti ' �,C..._/� _� P ,�� e+ .� � S� ? •• _\r `. `L~� . t j P��- r'�".� �•\ �'_ �' r, ,e= / � '' � 0.54� � d..� I�l, K r-� ..i ' (0.045' ) `%�� 8�r%" b � ,.-_,� r�:4 � niy• . �\ / sT2laCtoor�iT � \ 0.47' `�, (0.039' } " � • . - � .:�__. �� incorporated Area � �—�'� .� Rivedlake 0.47" � y �; ,,. — Major Road (o.0 3 9' ) 0.5 2• `� �r� (0.043' 0.65" ` NOTE:Areas east of the eastemmostisopluviai should use 0.65 �.56' (0.054') inches uniess rairrfall data is available for the location of interest (0.047') �The mean arrural sto�m is a conceptual stam faxid bY divi�9lhe amual predpdation by tha tdal nunber d sbrm everqs PK Y� result, generates lazge amounts of runoff. For this application,till soil types include Buckley and bedrock soils,and alluvial and outwash soils that have a seasonally high water table or are underlain at a shallow depth(less than 5 feet)by glacial till. U.S. Soil Conservation Service(SCS)hydrologic soil groups that are classified as till soils include a few B,most C,and all D soils. See Chapter 3 for classificarion of specific SCS soil types. 1998 Siuface Water Design Manual 9/1/98 .6-69 4. CONVEYANCE SYSTEM ANALYSIS AND DESIGN: Due to the small size of the project and a minimum of 12"diameter pipe used for collection of the drainage,the storm drainage system is over designed and conveyance analysis is not necessary. The developed 100-yeaz return period storm for the entire site only produces 0.64 cfs of flow. At 0.5%, a 12"diameter pipe can carry up to 2.7 cfs of flow. Therefore, the storm drainage system can be assumed to be adequately sized without further analysis. 5. EROSION CONTROL CALCULATIONS Design of the erosion/sedimentation control plan was compTeted in conformance with Core Requirement#5 per the 1998 KCSWDM. Compliance with the 7 minimum requirements are summarized below. 1. Clearing Limits: Clearing limits have been delineated on sheet C2.01 of the civil plans. The clearing limits extend only to those areas that will be disturbed during �' construction of the subject project. 2. Cover Measures: The temporary erosion and sedimentation control notes listed on ', sheet C2.01 of the civil plans specify specific times at which temporary and ' permanent cover measures will be installed. , 3. Perimeter Protection: Per sheet C2.01 of the civil plans, silt fence will be used for perimeter protection. Silt fence will be installed along the perimeters of those areas that will be receiving silt-laden runoff. 4. Traffic Area Stabilization: A construction entrance will be installed at the entrance to the project site. See sheets C2.01 and C2.31 for location of construction entrance and detail. 5. Sediment Retention: The proposed water quality/detention pond will be used for sediment retention. The required surface area is calculated below. Surface Area: SA=2080 sf/cfs * Q,o Q,o(Developed Site)= 0.38 cfs SA =2080 sf/cfs * 0.38 cfs=790 sf The surface area at the top of the proposed riser(Elevation 418.0) is 4,620 sf which exceeds the minimum 790 sf. 6. Surface Water Controls: Interceptor swales will be installed to intercept and convey silt-laden runoff to the sediment retenrion pond. See sheets C2.01 and C2.31 for location of the swales and detail. 7. Dust Control: A note on sheet C2.01 addresses the procedure for dust control should soils become too dry.