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Home My WebLink About02916 - Technical Information Report - Storm Drainage Calculations • � f � ' ^ 4205 148th Ave.N.E.Suite 200 � CORE Bellevue,Washingfon 98007 425.885.7877 Fax 425.885.7963 ` / DESIGN V E-mail:office@deionline.com .D- � l� PLAT OF EAGLE RIDGE RENTON, WASHINGTON for , PACIFIC HUTS AND CASTLES, INC. STORM DRAINAGE ; CALCULATIONS �� "�� Proj ect No.: 99102 '��.� - �? Prepared by: Brennan P. Taylor,P.E. � y `� Approved by: David E. Cayton, P.E. � � � Date: October 2000 33713 ��;q Revised: February 6, 2001 `��rsrE��4�.�' �'�°;�.�.��' ��s-�z- C� l �. - � �1 ,2 9/� . � � . i,; '� � +�' . �•� ��iii:� sit?'� STOR111 DRAINAGI CALCULATIONS TABLE OF CO?vTEN7 � ��;�:�„ I. lntroductiul: II. Offsite Anal� A. Upstream Drainage B. On-Site Drainage C. Downstream Drainage III. Flow Control and Water Quality Analysis and Design A. Hydraulic Analysis B. Detention Routing Calculations C. Water Quality Calculations N. Conveyance System Analysis and Design V. Erosion Control Calculations , � L Introduction The Eagle Ridge project is located in the southeast quadrant of the intersection of SE 128`� Street (NE 4�'St.) and 148`�Avenue SE in Renton, Washington. This parcel is approximately 4.2 acres and was recently annexed to the City of Renton in the � Maplewood Annexarion. An existing asphalt contractor occupies the adjacent property east of the site. The south adjacent parcel includes the proposed Plat of Maplewood. See Figure 1 for vicinity map. The majority of the site is currently young alder saplings, Douglas fir, western hemlock and other trees. The site generally slopes to the southwest at approximately 5%. No wetlands exist on-site. The proposed improvements include the construction of 17 single family dwellings with ' related grading, utility, and road construction. Onsite generated storm water runoff will ', be directed to a combination wetpond/detention pond in the southwest corner of the site. 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I 7f C � G G � � � i.i ibore� � � i � 'i•.I - I - , - _ � : � r �/ � �� I . �� . / =y . � : �'_ +' .u'-'w N I i ..��$ �� . � � �� nLw�n �tr� 4- 'i�:: A. � .I' ._ . � wn _� ' -� . �i C ..4<^', -_C r � ,}�` • W I � r ----E--' � — .r—� — �--��'�-' ---------t �- — — - — _ „ �r�wr l' Moi1Mr. r.. ' M:�::1'•..._ � � e C wn k r�:4';;: �"" . �� t ar ■ I � � � a � . .a� .ya �,�r'� I a r '� =� � + � ;' .. .'€ ( � �.� � V� �r� � �p � � � u ri,.4.'�.:�.� r m � r:�w:•:�.;�.=. �y /%': i I -a � G I �E�� I ��•'� � • ' �-. 1 q 1�! I l/�r I � � ...0 .! t M;� i'::.:��_-. ,"� _�,.� �� .a rj . „�, 3 �¢" ■�-' I ..R:�<• � ��'P�,"4z ..,�"r.�, � '�'� +�I �:; : : c �,. �,� � . ',:•:. I ., b :. Q r if.. �r }cv �� S �' �� i'.�... �� I { � .�-�''��`� ~ F �� !–— �— t � >Y Ti ti.��- � r M�" , " aTM'° y �...r _ g � `�'��-,':; M_:._..i_._�� . � � I p. �!i � � �� aa y � •,;��:; + � , �.0.�` � �� { ' �.. � f;� _ f m �' �' " � �'N�,a, � ,.? ' � m . : ... � ,, � .•....:. �. .... ;� „ _� `:j-:'..' ! ' " 1 A� L rY11 'Y.�.��' , � C � I . i ' � 3s n ��":' � � � s� � � � S,� 1` �4 � �, .. , . — A i �• � —5�� ` ��Y i'� —— - � _��— �Mmaw 1 I � S`F"': � .� ' 4 , �� •�fF - c� � n � VICINITY MAP �r .i-... �� '"� W a' � EAGLE RIDGE ,.•.' �'i`� �' e�'b � �� v �^� . � e� N • CORE DESIGN NO. 99102 ��+ KE G�{ON ai r ev , � � LAPSNt �. ...: = 1 r _ . }��:::;;'"�+.�, " II. Offsite Analysis A. UPSTREAM DRAINAGE There are no upstream tributary areas draining onto the site. Runoff from SE 128`� Street right-of-way drains to the south roadway ditch and flows west, off-site. This roadside ditch is drained to the southwest into a separate drainage basin via drainage ditches and culverts. Runoff from the adjacent asphalt company flows south onto the Maplewood property. See Figure 2 for Existing Drainage Basin Map. B. ON-SITE DRAINAGE Stormwater runoff on-site generally flows in a southwesterly direction over forested terrain to the 148"`Avenue SE right-of-way. 148�'Ave SE is currently under construction as part of the Maplewood Property project. There are no existing channels on-site all existing flows are sheet flow to the southwest. C. DOWNSTREAM DRAINAGE Runoff from the project drains onto the Maplewood Property site. The Maplewood Property project will improve 148`�Ave NE on the west side of the site and install a storm drainage conveyance system which accept runoff from the Eagle Ridge project. A 12" pipe form the new 148`�Ave SE conveyance system will be stubbed to the southwest corner of the site (Inlet 71A of the Maplewood Property project). As mentioned earlier, the Maplewood Property is currently under construction. The storm water runoff from the site is conveyed approximately 3�00 feet through the newly constructed storm drainage system of the Maplewood Property. The Maplewood storm system discharges to a pair of 24" culverts located immediately south of the intersection of 148�'Ave SE and SE 136`� St. The twin 24" culverts convey storm water to a grassy swale which runs southeast and then south for approximately 700 .�. • li II. Offsite Analysis (con�) C. DOWNSTREAM DRAINAGE (cont.� feet until it reaches a 30"CMP Pipe on the north side of the Plat of Briar Hills. This 30" CMP pipe directs the flows through the Plat of Briar Hills at varying slopes of 0.6 to 3.8% (see Figure 3 for pownstream Drainage Map). There is one "off-line"detention pond approximately 4900 feet downstream which is thoroughly grassed and shows no sign of recent inundation. The 30" inch CMP ultimately drains to another"off-line" detention pond approximately 5800 feet downstream near the south end of Briar Hills. This detention pond shows evidence of recently detained flows filling up the bottom 2 feet of the pond (the pond has seven feet of available storage). This pond releases to a rip-rapped discharge at the top of a natural drainage ravine. The ravine eventually discharges to the Cedar River approximately one and a half miles downstream of the subject property. The downstream flow path has no apparent signs of flooding or extensive erosion. 0 . . � . O � � � � . �' . � II a � T , , �I 0 . , , , Y , _ � . � . I • . — 3 ; ' � � � � � � = 1 �� • �''� '�� I j . i � - `r � 1 _ � � �1 - '�� i•� . � , i "�, €N � � ,Q y �m _ � 1 � � 4 , _ '..._ . ; , '- - � `,� t� ' ! j ' �.. M1M 1.. W.. �. . .. 1 ; • � ,:i .o � �` � ' a � °I 1 ' �l ' ti i ��r _'�� —�� ' �� +, tit a �,,;— p - z � , � : : . ;��: I � � . -- ---+u+w �� ' ` ' C g =: � z1 � ( � ' � '�y1'l,,,a '' �'! -x:; �. � a .e .t . , • r�. 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'�' �� j (��0�� ; a ' � s 1 � t ' � _ ° �� .� �8�1�AG� � - �� T ,�_ � _ •♦ •. . . � q,w �j � p� y - � 1 �� '`' : � t` °` '� ■�;" v� a� ,o� +� ; �� `' l r��..� � e \ , t i� '� �j t / _� . l . � - \ : . . . . � � • ....1 a � ' t � � ♦ ♦ ♦ � � '� i W • , �l � - + ' 1 [ , E s a s a v : :� :� .� e� ■� ma e � , � � �� ' , \� � � . : \ .1 v� 35a �'i��'uN�D �o '�; � , �, , ,, , ,` _� :� ,� _� , • ,� �_ . _• ,• ., . _ GOtJ ��ANG'E s`l�T� Qu° ' ,�P�� _ . . . � . , • � ., , = �, � . - � � ; +. � ` �. �+� ► � t �. � � � _ - , _ � � , � _ s . . (: _ , . . . - i.� � —�-- �.�.-- - -- -- — - - . . � ,• � _ . � _�-�� -�..�r-,.�,---- r-� � -+sd,� .a�.n v. .ss. ......e � S.iZCl3i . L. �� •� ,..,.e ' _ � .�.i e _ t � ;�y ; � ; . . f I '.si'_�� I � g � `�!" ° ' � � I T�� U � p DOWNSTREA1�T DRAINAGE MAP '! � ss � � --_-- - ' �.> ` _ _ b '��.�a�.zs � :� � � '�-�- —�.,� � , _� _:`� i �'��="" = `I ` Z� Q o � � EAGLE RIDGE �M �' � '� . � ;� :� 3 �, , �' �i ��,: �,y � '� � `' ( 0 CORE DESIGN N0. 99102 N .� ..l ` . � ; ��: ' "j �� I � � LL3 °, ; ��i I�' .�..... ..,..o. __ _:�* " ._,�---i�._...._ .__'�.___ --- --- ' = - , „ III. Flow Control and Water Quality Analysis and Design A. Hvdraulic Analvsis The drainage analysis was modeled using the King County Runoff Time Series software. The onsite soils are Alderwood, hydrologic group C and KCRTS group Till. See soils map included in Section 3 Offsite Analysis of this report. The site is located in the Sea- Tac rainfall region with a location scale factor of 1.0. Existing Conditions The site is 4.21 Acres in size. The existing ground cover is till-forest. The following information was used for generating time series and flow frequencies. EXISTING CONDITIONS Total Area=4.21 acres 99102ex GROUND COVER AREA acre Till-Forest 4.21 � Onsite existing conditions flow frequency analysis: � PEAK FLOW RETURN CFS PERIOD 0.340 100 ear 0.315 50 ear 0.265 25 ear 0.204 10 ear 0.196 5 ear 0.172 3 ear 0.117 2 ear 0.072 1.3 ear 0.007 1.1 ear •-—--`�=--—�� _� `�'`' `�' ' . .i _ '.-�^a �� i �^v� _T —�I . .' / . - , � ` � r. - , ;5.E. 12�8TH ST:'f '= � � �:'�—c– Ir ---�-- � �–'� –�,� –:��E4'''�' S"r� � ��,. ol 1 � � � \ v� --�— �� •.� �. I . _ _ — _ �~__ __ _ _ , �� —_ _ , __: _.__ __ � _ —...—..._.— �.--.�,...—... _� , __ __ �. _. ..._..._.� _ �.�. ; --- 4 0.52 � � . LJ� • � � ,�. I i .� . .`O'� j „ \ 1 j Op .'2f. . I I RC_� t • � ,'1 �I ' � `\ �,� � ,\ `1 � • ,� �.7 - �� ; 'ti I ',, �� ` . ,`� r � '� � � '�. � 7�� ..8�> ,� �,�� `1 � •� '1 � � I, . _ ,� � ` \ c � Z I �� 1 `,qb2 �1 p I ,P I � �'�` � 7 II � , �.� j .�. ��rs �� ,` ..�. �� C � �� • ',. �� 1, � a � � I �ry' •�- ,�� "--., —T—_� ' � � �� 20' ACCESS � �� ACC£SS � 1 I \ , Uil TY EASEIAENT / UTY E7ISEMENT` �j.�'�iry! ',\ �c \ ., � �.-1'�� j �1 't ' I •��,� _�� / � ,1:i ��\ � � j ' � �2p'Y'��. 'I �� '� , � 1.2 � �. � 3 , �! , i li I p �,,_ '� t i�P � �� '� '�,.�l � * '�� '� . ; �� .� � `� ;� ,0.� � . .� . � � I / ' �� ry� � \ �` ` �R'A� �� M�F . W I i ! • \�`` ,1 `� k 4fEl � � ��+ \ '� 1 ��p � I ';j ' w •.. ��__ -f � � , 1 c� � � l `� f,' 1.8 I 1 � '- •,�--.`� - � �,' � 5 1 i � t�� u, - � 00 00 �, i, '� � i • .J �f'� � ` � t \ � ;�i ^ � 'i \ �I � � � �` w � °� � � 1�' ..��1{{I f _'- ' Z \ �� '� 1 �\ � .\ K�� - "`'�. ' m� \ 6',,f�ct -->>lI \ e � Z ` •P 1�� .�` 1 .` � ,.\_.,` � � � ��r ,ryhy� � t�\ 21� P.�'S •�1 `t\ �'-.,�� ,� j � • ,�� `R �� ``� .�� 1� , 'Yp! � � 1 � � ,�` � � �� V i I i �•ry� •� ` � IJJ �ti\ `•,� ,,i';,`� � � l` r+.'_. P f r � . !Q � �l'. ` - �_�- �� —�'i�'� N88'21'19�W �1� '•`t�', 1 `� f �� '� � �� 429.81 � - - - �, - � '�'; I �� ; N l� � �5 •'-�I ; � � �d, � � ` \ • 'i .I I ��' ��►' h �\16 `�� 1�3.� � `� :t `�� I+ �g ,' \ �� I I i I . �� '' , �� ' `'\� ; I, ! j I � l� �. �;�` -. `' .�'1� ��, 17 .0 16 � 15 �•�- �1'�4 ; i � STORM RAINAGE OPEN 3 \ •ry�� ,o`. ' ; � � �`� .R� `h� `�� '_e�' •'�hR 1i�1, .3,0� `` �-,, I � `� � � 6 �J � �� j� � �� `��l 1 i ` �r � �'�` � ,h�� 1 ti� . .n.� �; , ` � , , ; b'�' 1 I .. � N 88` , �j,�j P �� P 4'.�.( l�G O�'T��I ��2.5'� i ON-SITE � , 1 � ; • � � � , BASIN MAP ''�� :�2,4c�o� �tl I ,��,'��- '�:;� '' �� '` p L D� '�! -�C"�Fr"'"�'• EAGLE RIDGE ii�y i ��._1� � � ' P� pp0 i T ',I1� ' ' � � � E�t � � CORE DESIGl� NO. 99102 �t� , � � � � ,, ` `, , `�. : � .�P�- . Flow Frequency Analysis Time Series File:99102ex.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 0.265 2 2/09/O1 16:00 0.340 1 100. 00 0.990 0.072 7 1/06/02 3:00 0.265 2 25.Q0 0.960 0.196 4 2/28/03 3:00 0.204 3 10.00 0.900 0.007 8 3/24/04 20:00 0.196 4 5.00 0.800 0.117 6 1/05/05 8:00 0.172 5 3 .00 0.667 0.204 3 1/18/06 21:00 0.117 6 2 .00 0.500 0.172 5 11/24/06 4:00 0.072 7 1.30 0.231 0.340 1 1/09/08 9:00 0.007 8 1.10 0 .091 Computed Peaks 0.315 50.00 0.980 � ' SHEET NO. lI KING COUNTY AR,EA, WAS�- �� (RENTON QUADRANG � ) nn,,, rssaouaH �a Mr. 10' 1 680000 FEET 122°07'30" ; 4 7"a�' �i � • J�i� . . . • AgD .... . . . r Y � ;= •�� ' � • _• . • •n•� � • n 1 . •q AmC � . .' �'�s�n � � `.,�i�� ,, � .. s�y . yec i ,� t�;�� _ . . o , ' , asc� •'� i�i� 14 � i ' � ' �...«. � . � ``-. _� �J ,g . � a2s. �� . . . . �:' 4, �1� �8N��9�5 ' .� . . i I' ' .' `. _ � -?1� aes .' .� •--- y r: '" , � . .. .' �:__ __ � . � � � „ : , � • ,o �i . a, , . . .. u'• �'__ ____ ____ �`--' ,•� � Trailpr . • •: • -- I � ♦�■ ■• � � . �: M.Ev8 M , � . . . �. ark�•' . x = u .8 �igM • II hi___•ti •• ' • �• .1 {� � . � "i � � ; �• ' ' N � 3 424 .. . � �6 � -1 " � . 6 •__---7_• � •u I� �Greenwood(� � : !! ..... I � � �—� � • � � � , � 180 000 s�====_� ° '� ' �� . "� 't =. _ ��T� , • , FEET { I N �o � .. 4� � •r• I �' iC � � � �1. ;' �,� u q� � ' • �; @ M � aa \ � • qvEt. '�P�T �::� +i � , a µ �y� V+ � � �� .. �.. � .I'. 1 y i Y • '� ---sa= _� �2�. �.� � ; b .•15'• --- 14 ��___' �, N �N��• _ �` M ? � S• r''� � � � � .�° .. W � �� . I W EvC -- -IAkF oee�� .....r P i ' l. A � � ` �I�sr .� i a �' �•.✓` � M ' — � ' ,R,aa�sf � •'...�,.� �� . ' � L'__� - I •��' •r. y py ~ i / �.•k . n:� j --.0 � ' .•� ii � 8M ��' � „---il , . �� ' ,. �i ; 3 ,ri � — - "--•� ••`� ---'+oj—� --------- y ' —.-- Ev8 � --- — ��.. . ----� � ...�r --�----- ,—��a��:�_'_' •. • A� j�jv�'li' '�Py �•,Ma �Se I • .r,. .µ - ��\' .`�� A C � �f��se � � n EuB II m - _�- - --�r�.------ / AkF � 1 `�' � i' -�-r,__s ' '-•---- � � ��'�a, �`' Rh o P y,r� .,e: " a l" - � ., . Y � ! IY�B I - �� ' > ;;�� , •�'.•' , , ,-. � � 'a akF i- /� .< �., AgD �`1 •ii� ` � Py � P� ��o ��` --�- �.' � �. • n C ,y� `� • a • i e ,�A`�.,_AkF=,__c_a :`\ ap• y.. b y '� 11t sa1V8 I' � E, .py Ma �w ♦ i'atsa' ��`a`� � ki 1 I� '' +� p 21 � ��` _ � . Q �� o n j. h ( �n jii �� ' IOt P�• •Rh W y +�+Xr6 I ur' I • �� J� " FY � �C �+ �►BC ��a•�r ,AkF I p p �� ad '��. Ur �r Q , � ° ( w�� AkF N � y �.�� ,`, �� qgC u Park � � P AQVE. \\c%N �.w� � �� y 169 ' Z u ` ��`��° C �� \C.n '1.0;' EvC � �ii I M � B` ``'' A6� AkF A 2 �. -- -- -- — +. ----- --- — --- ---- ------- I ,� '�_'b- --_---- ---— �- -1- �--- --- °'"- - .� -- -•_°__==-�---�-- -• -- A B �' � HING COUNTY ' � nac neo,,-- , SOILS MAP —�' sMm ' �`. I a28 i`2 ` � EAGLE RIDGE AmC � � ACB,i f1m8 � ' i ` 27 CORE DESIGN 1\TO. 99102 Ur � ' 492 � � � � � _ .�_ '� � � �:o.o�' 1��. F�.��' 1 !� V 1 • • �� 3.2.2 KCRTS/RUNOFF FII.ES METHOD—GENERATING TIME SERIES TABLE 3.�� EQUIVALENCE BETWEEN SCS SOIL TYPES AND KCRTS SOIL TYPES SCS Soil Type SCS KCRTS Soil Notes Hydrologic Group Soil Group Id ABACAD C Arents,Alderwood Material (AmB, AmC) C Till Arents, Everett Material (An) B Outwash 1 Beausite (BeC, BeD, BeF� C Till 2 Bellingham (Bh) D Till 3 Briscot (Sr) D Till 3 Bucldey (Bu) D Till 4 Earlm�nt(Ea) D Till 3 Edgewick (Ed) C Till 3 , Everett(EvB, EvC, EvD, EwC) A/B Outwash 1 Indianola(InC, 1nA, InD) A Outwash 1 Kitsap (KpB, KpC, KpD) C Till Klaus(KsC) C Outwash 1 Neitton (NeC) A Outwash 1 � Newberg (Ng� B Till 3 j Nooksack (Nk) C Till 3 Norma (No) D Till 3 , Orcas (Or) D Wetland I Oridia (Os) D Till 3 Ovall (OvC, OvD, OvF) C Till 2 Pilchuck(Pc) C Till 3 � Puget (Pu) D Till 3 Puyallup (Py) B Till 3 Ragnar(RaC, RaD, RaC, RaE) B Outwash 1 Renton (Re) D Till 3 Salal (Sa) C Till 3 Sammamish (Sh) D Tifl 3 Seattle (Sk) D Wetland Shalcar(Sm) D Till 3 Si (Sn} C Till 3 Snohomish (So, Sr) D Till 3 Sultan (Su) C Till 3 Tukwila(Tu) D Till 3 Woodin�ille (V11o) D Till 3 Notes: 1. Where outwash soils are saturated or underlain at shallow depth (<5 feet) by glacial till,they should be treated as till soils. 2. These are bedrock soils, but calibration of HSPF by}Gng County DNR shows bedrock soiis to have similar hydrologic response to till soils. 3. These are alluvial soils,some of which are unde�lain by giacial till or have a seasonaliy high water table. In the absence of detailed study,these soils should be treated as till soils. . 4. Buckley soils are formed on the low-permeabifity Osceola mudflow. Hydrologic response is assumed to be similar to that of till soils. 1998 Surface Water DesiDn Manual 9/1/98 3-25 . SECTION 3.2 RUNOFF COMPLTTATION AND ANALYSIS MEI'HODS KCRTS Land Cover Types KCRTS supports four land cover types:forest,pasture, grass,and impervious. These cover types shall be applied as specified in Table 3.2.2.0(below). TABLE 3.2.2.0 KCRTS COVER GROUPS AND AREAS OFAPPLICATION KCRTS APPLICATION Cover Group p�evelopment Post-Development Forest All foresUshrub cover, irrespective of All permanent(e.g., protected by age. covenant or SAO designation} onsite � foresVshrub cover, irrespective of age, planted at densities sufficient to ensure 80%+canopy cover within 5 years. Pasture Al! grassland, pasture land, tawns, and Unprotected forest in rural residential , cultivated or clearet! areas, except for devefopment may be considered half lawns in redevelopment areas with pasture, half grass. predevefopment densities in excess of 4 DU/GA.. Grass Lawns in redevelopment areas with All post-development grasstand and predevelopment densities in excess of landscaping and all onsite forested land 4 DUlGA.. not protected by covenant or SASA �� designation (except in rural areas as noted above}. Wetland All delineated wetiand areas(except All delineated wetland areas(except cultivated/drained farmland). cultivated/drained faRnland). Impenrious�'� All impervious surfaces, induding All impervious surfaces, including heavily compacted gravel and dirt compacted gravel and dirt roads, parldng roads, parking areas, etc., and open areas,etc.,and open water bodies, water bodies (ponds and lakes). including onsite detention and water quality ponds. �� Impervious acreage used in KCRTS computations should be the effective impervious area (EIA). This is the gross impervious area multiplied by the effective impervious fraction (see Tabfe 3.2.2.E, p.3-28). Non-effective impervious areas are considered the same as the surrounding pervious land co�er. The following four factors were considered in specifying the above land cover types to be used in hydrologic analysis with KCRTS: • Cover types are applied to anticipate ultimate land nse conditions. For example,probable clearin� of woodland after development is nominally complete suggests that the post-development land use be specified as grassland(either pasture or grass)unless the forest cover is protected by covenan� � In areas of redevelopment,there are often significant changes between the predevelopment and post- development efficiencies of the drdinage system. For example,in conversion of low densiry residenrial areas to higher density land use,impervious areas prior to redevelopment may not be eff'iciendy connected to a drainage system(e.g.,downspouts draining to splash blocks, ditched instead of piped roadway systems). These problems are addressed by defining an"effective unpervious fraction"for existing impervious areas and by generally requiring predevelopment grasslands to be modeled as pasture land. 9/1/98 1998 Surface WaterDesign Manual 3-26 � � SECTION 3.2 RUNOFF COMPUTATTON AND ANALYSIS MEI�iODS FIGURE 3.2.2A RAINFALL REGIONS AND REGIONAL SCALE FACTORS ST 1.0/ � ST 1.1 ( ST 1.0 LA 0.8 LA 0.9 LA 1.0 LA 1.2 � SMOMOYISN COUMT♦ � 1'� '��i j. ' �� M KINO COUwTi i."y�t�� 'p�'�� ^-T+` 4 � �. / r�^� / :� 1 � 1� i/. � 1 .' S \~�� ..-. � ' L; � � ' r- 1 __...r��i i, � `�s� -,. — '�'�'i`=1 �' i l ` t" �B i' . _ �� ,� � .—, .'' r "t �io.o�o � ' J � t. � � � � 5 l.�� $V ; l r r',a or+�`,_ � .; -1' '� , � , -�' (— , �� )� � J '�� .:� t�� .;:, � e .l � � � ,- ' f 1 t /"` ��. � 3 �' ",.'�`,� �.�.:f _ �~ �i r � �d - � 4� ! � � �` � euE+�iE' � � / ,,,"l� �.�1, A '—,.�_ M : + ` ...z� ;�� . 3,(. `^ � � � : YIKEM .� . � ` .�' \ �. �� F ; � � L '�� / n '�� \� �� f�til'" '� ��1 "r n'~`` � �``' f S µ _ .. ' i I .. ' .I /�i��. _: SE�7TCE= :� � . .. ,- . . �� /� : T—;-�� _ ` ' ��..OY.M.. � `` �� s� �I r.,.!l. � '`' �A\�C.+ � I:i I J + w��io. � �.- �--, : r . �� r - �:r~ '^� '� � �.. �� , _ . J '� y.. �: ;. ° _ ,;, -�� p j, _ _ � � I ,��_� �°�5 T�� _- �; .� ' , � �,.� � i ,� .- :, a � = , � LANDSBURG �.�. � l o �� o �. : ��:� � , - :�s- _- _ :� Q . \ o _ . ,� i!'.�.,�j ! : �--� ' �, � _ � - �_� i � f �' �^ u�e�we Pi � �•f�, ��y=^\ `. p .:3 ,,r , r� V � . `_ • � a �� .�, � �^\�= � . _:.� , f ��rJ "'�\ �i�-- liaci� � a_ ' ,i r , - - °""'4"' [,, • ST 1.1 � `i-''"� ^ � . � i �� .r ." .� - �_ ,- :i B',.�`�_ : - 6 ��uro�eouwrr � I1lRCf COYMT• � ST 1.0 � , � i . �— _ S►v- Rainfall Regions and �o$� 1 � Regional Scale Factors �a o.s � � � Incorporated Area LA 1.0 L�► 1.2 �.� RivedLake Major Road 9/1/98 1998 Surface Water Design Manual 3-22 Developed Conditions The developed site will consist of 17 single family residences with associated roadway and utilities The impervious area was calculated using the criteria in the 1998 King County Surface Water Design Manual page 3-27 which states that 4000sf of impervious per lot should be assumed. All other impervious surfaces were measured by a planimeter. D. Impervious Area Delineation Onsite road and sidewalk 28,960 sf Im ervious area of lots 4000sf*171ots 68,000 sf Total im ervious area 96,960 2.22 acres) The input used for the KCRTS analysis is suminarized in the table belo«�: DEVELOPED CONDITIONS Total Area=4.21 acres 99102dev GROUND COVER AREA acre Till-Grass andsca in 1.99 Im ervious 2.22 Onsite developed conditions flow frequency analysis PEAK FLOW RETURN CFS PERIOD 1.47 100 ear 1.27 50 ear 0.865 25 ear 0.857 10 ear 0.758 5 eaz 0.716 3 ear 0.716 2 ear 0.590 1.3 ear 0.565 1.1 ear Flow Frequency Analysis Time Series File:99102dev.tsf Project Location:Sea-Tac '' ---Annual Peak Flow Rates--- ----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob I (CFS) (CFS) Period 0.716 5 2/09/O1 2:00 1.47 1 100.00 0.990 0.565 8 1/05/02 16:00 0.865 2 25.00 0.960 0.865 2 2/27/03 7:00 0.857 3 10.00 0.900 0.590 7 8/26/04 2 :00 0.758 4 5.00 0.800 0.716 6 10/28/04 16:00 0.716 5 3.00 0.667 0.758 4 1/18/06 16:00 0.716 6 2 .00 0.500 0.857 3 10/26/06 0:00 0 .590 7 1.30 0.231 1.47 1 1/09/08 6:00 0 .565 8 1.10 0.091 Computed Peaks 1.27 50.00 0.980 1 �. B. Detention Routing Calculations The detention/water quality facility will be a combination water quality and detention pond. Per the hearing examiner's conditions, the facility will be designed according to the Sept. 1998 KCSWDM instead of the 1990 KCSWDM that is normally required in the City of Renton. Since the level of protection was not specified by the hearing examiner, the detention portion of the pond will be sized according to a Level 1 Analysis (Conveyance Protection) using the KCRTS soflware. The Level 1 Analysis results in a 276% increase in detention volume from the 1990 KCSWM methods used in the preliminary storm drainage calculations. Sizing the pond by the 1998 KCSWDM and KCRTS Computer Software Reference Manual, the 2 and 10 year flows are matched. Since the KCRTS softwaze is not ven�user friendly when custom stage storage relationships are used, the actual stage storage relationship was approximated with a trapezoidal pond having a similar stage storage relationship. The attached table shows the relationship of the Actual pond to the KCRTS trapezoidal pond. The flows to match for the 2 year and 10 year flow aze 0.293 cfs and �.5f1� cfs respectively. The following table summarizes the routing results. I ROUTING RESULTS 2 ear storm i� �:;�r �� allowable release cfs 99102 re 0.12 0.20 I�� into ond cfs 99102dev 0.716 0.857 '�, Qp released from the design pond 0.0.12 0.20 cfs) 99102out Pond live storaQc re uired (CF) 17,445 27,016 The control structure has ? orifices to meet the detention criteria to match the 2 and 10- �� year storm events. The first orifice has a diameter of 1.64 inches. The second orifice is at I a stage of 2.70 feet with a diameter of 1.54 inches. � The primary overflow for the pond is the riser pipe within the control structure. The KCRTS program calculates the overflow over the riser when routing the hydrographs through the detention facility. This is evidenced by the fact that the riser stage is 3.7 feet , and the maximum stage of the detention pond 3.86 feet. This translates to a maacimum �I water surface of 442.86. ' The secondary overflow for the pond will be via a j ailhouse weir. The overflow elevation for the 100-year developed flow will be calculated assuming there is a blockage in the I control structure. The jailhouse weir can be analyzed using the standard weir equation: I Q = 9.739DH3;2 where Q= flow (1.47 cfs) D=riser diameter(4 feet) H=head above weir(ft) The head required to drive this flow is 0.11 feet. The CB structure is placed at the overflow elevation of 442.86. The secondary overflow elevation is therefore 442.86 + � 0.11 = 442.97. In addition to the se�c�ondary emer�enc�- overflo«-, the City requires an emer�ency �� overflow spillway. The primary overflow elevation is EL 442.86 (shown as design ��ater surface on the plans). The secondary overflow flow elevation is EL 442.97 (shov�m as overflow elevation on the plans)which will also be the top of the rip-rap of the I emergency overflow spillway. The required spillway len�h is calculated below. L = (Q�oo/(3.21H3;`)) - (2.4H) Q,�= 1.47 cfs (tributary to pond) Assume H=0.2'(minimum value) L= (1.47/(3.21(0.2)3n)) - (2.4(0.2)) =4.64' The minimum length of overflow spillways is 6 feet. The emergenc}� overflow elevation of the spillway is EL 442.97 + 0.2' =EL 443.17 POND VOLUME CALCULATIONS (LNE STORAGE) CORE # 99102 BUTTAR PROPERTY �C R��J STf�G��STo�6� LEVATIO INCREMENTAL TOTAL VOLUME VOLUME uD�- SF CF CF G�F) 439.0 50�0 � �� p � -,�� 440.0 6472 '. � /_ �.�-6 -rj �o �� 15,232 � � 442.0 8760 ?1,U0� Zp(a o4.. 9,400 443.0 10040 30,408 �a�'S� 10,730 444.0 11420 41,138 �"09 59 �� SNOI�J� � Tt1E 12f6N? T�'E K�-�-TS S"f�GE�S'TD�Ab� J ��,�T Ic��i SN �P �S f�PP'P.t�1C� w►ArTt`�-�/ T�� Sk+'+�E A S i `C'k�� Gi u a i. �o�•SD z-C�b��sTaR.Ab�. � �GT�A�L PoN� <<, 5�ibtl?� V�Q.I�R '�� "j�iE KC-R.T'S [Z�Q�� onL� A�N� "T��.Ef0�2.� IS �l,l6 �T l� COrJS��'��. �� , , Retention/Detention Facility I Type of Facility: Detention Pond Side Slope: 3 .60 H:1V Pond Bottom Length: 85.14 ft Pond Bottom Width: 60.38 ft Pond Bottom Area: 5140. sq. f� Top Area at 1 ft. FB: 11210. sq. f� 0.257 acres Effective Storage Depth: 3 .70 ft Stage 0 Elevation: 439.00 ft Storage Volume: 27067. cu. ft 0.621 ac-ft Riser Head: 3 .70 ft Riser Diameter: 12 .00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0. 00 1.64 0.140 2 2.63 '_.46 0 . 060 4 . 0 Top Notch Weir: Noae �%a�-1:,�.ti� Ra._�nc C��_ �,re : T�;oae Stage E1evaCior. Stc�age Discna�ge Percoiatior_ Surf �rea (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq. ft) 0.00 439.00 0. 0.000 0.000 0 .00 5140. 0.02 439.02 103. 0.002 0.010 0.00 5161. 0.03 439.03 155. 0.004 0.013 0.00 5172. 0.05 439.05 258. 0.006 0.016 0.00 5193 . 0.07 439.07 362. 0.008 0.019 0.00 5214. � 0.09 439.09 467. 0. 011 0.021 0.00 5235. �I 0.10 439.10 519. 0.012 0.023 0.00 5246. �� 0.12 439.12 624. 0.014 0.025 0.00 5267. � 0.14 439.14 730. 0.017 0.027 0.00 5288. 0.15 439.15 783. 0.018 0.029 0.00 5299. ' 0.25 439.25 1318. 0.030 0.037 0.00 5406. 0.35 439.35 1864. 0.043 0.043 0.00 5514 . 0 .45 439.45 2421. 0.056 0.049 0.00 5622 . 0 .55 439.55 29B9. 0.069 0.054 0.00 5732 . 0.65 439.65 3567. 0.082 0.059 0.00 5843 . 0 .75 439.75 4157. 0.095 0.063 0.00 5955. 0 .85 439.85 4759. 0.109 0.067 0.00 6068. �.00 5(pQj?j 0.95 439.95 5371. 0.123 0.071 0.00 6183 . 1.05 440. 05 5995. 0.138 0.075 0.00 6296. 1.15 440. 15 6631. 0.152 0.078 0.00 6414. 1.25 440.25 7278. 0.167 0.081 0.00 6531. 1.35 440.35 7937. 0.182 0.085 0.00 6649. 1.45 440.45 8608. 0 .198 0.088 0.00 6769. 1.55 440.55 9291. 0 .213 0.091 0.00 6889 . 1.65 440.65 9986. 0 .229 0.094 0.00 7010 . 1.75 440.75 10693. 0 .245 0.096 0.00 7133 . 1.85 440.85 11412. 0 .262 0.099 0.00 7256 . 1 .95 440.95 12144. 0 .279 0.102 0 .00 7381. 2.05 441. 05 "�288n. G.G96 G . iG4 G . 00 75�_ 2.15 441.15 13645. 0.313 0.107 0.00 76�: 2.25 441.25 14415. 0.331 0.109 0.00 7760 . 2.35 441.35 15197. 0.349 0.112 0.00 7889 . 2.45 441.45 15993. 0 .367 0 .114 0.00 8019 . 2.55 441.55 16801. 0 .386 0.116 0 .00 8149. ' 2.63 441.63 17457. 0 .401 0 .118 0 .00 6255 . 2.65 441.65 17623. 0 .405 0.119 0 .00 8281. 2.66 441.66 17705. 0.406 0.120 0.00 8294 . 2 .68 441.68 17872. 0.410 0.123 0.00 8321. 2 .69 441.69 17955. 0.412 0.126 0.00 8334 . 2 .71 441.71 18122. 0.416 0.131 0.00 8360 . 2 .72 441.72 18206. 0.418 0.136 0.00 8374. 2.74 441.74 18373. 0.422 0.139 0.00 8400. 2.75 441.75 18457. 0.424 0.141 0.00 8414 . 2.77 441.77 18626. 0.428 0.143 0.00 8440. 2.87 441.87 19477. 0.447 0.152 0. 00 8574 . �'�-� Z��F 2.97 441.97 20341. 0.467 0.159 0. 00 8709. 3.07 442 . 07 21219. 0.487 0.166 0. 00 8846. 3.17 442 .17 22110. 0.508 0.172 0.00 8983 . 3.27 442 .27 23015. 0.528 0.178 0.00 9121. 3.37 442 .37 23934. 0.549 0.183 0.00 9260. 3 .47 442 .47 24867. 0.571 0.189 0.00 9400. 3.57 442 .57 25814. 0.593 0.194 0.00 9541. 3.67 442.67 26775. 0.615 0.199 0.00 9684 . 3 .70 442.70 27067. 0.621 0.200 0.00 9727. 3.80 442.80 28046. 0.644 0.513 0.00 9870. 3.90 442 .90 29041. 0.667 1.080 0.00 10015 . 4.00 443 .00 30050. 0.690 1.810 0.00 10161. 4 .10 443 .10 31073. 0 .713 2 .610 0.00 10308 . 4.20 443.20 32111. 0.737 2.900 0.00 10455 . 4 .30 443 .30 33164. 0.761 3 .160 0.00 10604 . 4 .40 443.40 34232. 0.786 3 .390 0.00 10754 . 4 .50 443.50 35315. 0.811 3 .620 0.00 10905 . 4.60 443 .60 36413. 0.836 3 .830 0.00 11057. 4.70 443 .70 37526. 0.661 4 .020 0.00 11210. 4.80 443.80 38655. 0.887 4 .210 0.00 11364. 4.90 443 .90 39799. 0.914 4 .390 0.00 11519. 5.00 444.00 40959. 0 .940 4.560 0.00 11675. 5.10 444.10 42134. 0.967 4.730 0.00 11832 . 5.2Q 444 .20 43325. 0 .995 4 .690 0.00 11990 . 5.30 444 .30 44532. 1.022 5 .050 0.00 12150 . 5.40 444.40 45755. 1.050 5 .2�0 0.00 12310. 5.50 444.50 46994. 1.079 5 .340 0.00 12471. 5.60 444.60 48249. 1.108 5 .490 0.00 12633 . 5.70 444 .70 49521. 1.137 5 .620 0.00 12797. Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 1.47 ******* 1.08 3 .90 442 .90 29046. 0.667 2 0.72 ******* 0 .52 3 .80 442 .80 28067 . 0.644 3 0.72 0.20 0 .20 3 .70 442.70 27052. 0.621 4 0.76 ******* 0 .19 3 .46 442.46 24792. 0.569 5 0 .86 ******* 0 .18 3 .38 442.38 24026. 0.552 6 0.45 0.12 0 .12 2 .63 441.63 17453 . 0.401 7 0.56 ******* 0 .10 1.87 440.87 11558. 0 .2E5 8 C .59 ******* C , �B 1 .30 440 .3C ?593 . 0 . 174 Route Time Series through Facilit-. Inflow Time Series File:99102� Outflow Time Series File :r�ou� Inflow/Outflow Analysis Peak Inflow Discharge Peak Outflow Discharge: 1. �8 CrS at S : uG on ,7an 9 �r_ �ear c Peak Reservoir Stage: 3 .86 Ft Peak Reservoir Elev: 442 .86 Ft Peak Reservoir Storage: 28616. Cu-Ft . 0.657 Ac-Ft Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS} (CFS) (ft) Period 0.535 2 2/09/O1 15:00 1. 18 3.86 1 100.00 0.990 0.100 7 12/28/O1 17:00 0 .535 3.77 2 25.00 0.960 0.188 5 2/28/03 7:00 0.204 3 .70 3 10.00 0.900 0.083 8 8/26/04 6:00 0.191 3 .46 4 5. 00 0.800 0.118 6 1/05/05 16:00 0 .188 3 .40 5 3. 00 0.667 0.191 4 1/18/06 23:00 0 .118 2.63 6 2.00 0.500 0.204 3 11/24/06 8:00 0 .100 1.87 7 1.30 0.231 1.18 1 1/09/08 9:00 0.083 1.30 8 1. 10 0.091 Computed Peaks 0.965 3 .83 50. 00 0.980 � � C. Water Quality Volume Calculations ' Based on the location of the site, `Basic Water Quality Treatment"is required for sizing the wetpond. The required volume of dead storage will be designed per KCSWDM Section 6.4.1.1. The following variables were used in the calculation: Volume Factor(� = 3 Rainfall =0.039 feet or 0.47 inches Where A;= area of impervious surface=2.22 Acres = 96703.2 sf A,g= area of till soil covered with grass= 1.99 Acres= 86684.4 sf. , Vr=[0.9A;+ 0.25A,g] x (R/12) I' Vr=[(0.9)(96703.2)+ (0.25)(86684.4)]0.039=4239.5 CF Vb=f*Vr= 3(4239.5)= 12,718 CF I The volume provided is 13,270 cubic feet. See the volume calculation sheet on the next , Page• POND VOLUME CALCULATIONS (DEAD STORAGE) CORE# 99102 BUTTAR PROPERTY LEVATIO AREA INCREMENTAL TOTAL (CELL1&2) VOLUME VOLUME SF CF CF .1;-�.fl �l�i Q 1�.? (.1 -��9.(i -�,9� 1;_�';{� I�j2 �70 GF � t2 ;1 �� GF �fZ-£�?'� . ✓ O, K. IV. Conveyance Calculations The proposed conveyance system performance was analyzed using the rational method. The system was modelled using the 25 year and 100 year design storm events. The subbasins used to calculate the runoff contributing to each structure are shown on the attached map. Runoff coefficient values for each subbasin were selected based on the developed characteristics of each individual area, impervious pavement (C=0.90) or lot areas (C=0.60). The attached Storm Conveyance System Design spreadsheets compute tributary flows using the rational method as discussed previously and present a sununary of pipe capacity flows. The tributary flows were inserted into the attached Backwater Calculations spreadsheets to calculated the headwater elevation at each structure. The last column in the spreadsheets (untitled)reflects the difference between each structure rim elevation and the calculated headwater elevation at that structure. Per attached spreadsheets, all pipe segments have sufficient capacity to convey and contain the 25 year and 100 year storm events, per Core Requirements#4, 1998 KCSWDM. . NW 1/4� NW 1/4, SEC. 74, � wr. 1:3 IV., nuc. � c., ...m. $ M n O � , _ � � � � � 30� � �0' � i. 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' ,.i ` �1 `i i. ;�' '� k �� - ' � --�-=-�c� _ �` `_ �1 ti' I �� ',� i�;�� i ; � � ' ,,l��` EAGLE RIDGE r i ��I � ' -- ��' - ` '� , '� j tjll � I �` —�' ; � � CORE DESIGN NO. 99102 � � - -- o i �� i ' ` ,. Z � � ,.. . ,. ,. - � '::::S�E�R� C(�1��;L��;��E;S�S`�'��'I T1E��+�N '.:: �� . . - . . _ )('ATION• KINC COUNTY 24 HR RAINFALL• 3 46 INC'HES JOB NAME: EACLE RIDCF. JOB NUMBER: 99102 1'ItF.I'ARF.D BY: llEC DESIGN STORM: 25 YF.AR . .; ,, UvEzx kNta : k N'FP M�h3Y0US .. T.EA�t� kniNF�i�p:I REblrh Y ' vlt . i:.ihE RtY�E:' :AG�UA3. ..?kAvf.L 1!1�fE:�A�l��I�:�4�MM:kItY".:; E?l1,,. ,.4_. .....U,A.,. ..!. �. Q . ... .. .':':':':`.. �... . � . . ' ':':'. �.. 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AE V��: R):df��1L -� d i�.�� ' u v �7 v� v ia�vu4 'rvti��a: ::�aia:: :':�n� ..' : �ai�:: :: n��i ia i. 1�7v� i a ,c..u >no�nu�w�:: a�aah8 . ^� s abw.��:iui �u.� W fi.�J.t�.a �d�ld:: .... �. ' 21V�A 00I =WNO,LSNDIS84 ��Q ��CflQ�Zltld�2ld Z016G �N:�UWIINflOf 8')(IINe'17V3 �3WVN801 - 'i':�:�s:��i�'�'�:'��:�:�'�:'�'i`'''�'�:��'':�'�'��::";:r"�:.i'i;i'i;��':�r::��::i��:�:�:��:�"'�:�'�:�':i�:�':i:i�i�i�i�i�i�::: S�IIJNI 56'£ �'I'IV3NIVtI NH-tiZ A.LNf107�NI>I �NOI.LVJO I \7��C'�� iA��f'� r7'''1�,"[`�.j��,1��(`1�. ��TO T� 1\t i'.1 1!:\L J.i��:ltY;i)' 11 �l�/ (1 iLi A6. .AT�h.E!�14CULn'1'lV1�S • JOB NAME:��EACI.N;RIUGE PREPARED�BY: DE CAY'I'UN I _ J06 NUMBER: 99102 DESI4N STORM: 25 VEAR ENTRANCE ENTRANCE F.XCI' OIITLET INLET APPRIIACH BEND JUNCTION � PIPF. PIYF. MANNINC'S OUTLET iNLET PIPE FLOW VELOCI7'Y AILWATE FR1C7'IUN H(:1. HEAD fIEM CONTROL CONTROL VELOCITY HEM HF.AU iEADWATER - FRUM 'f0 FI.OW LENGTH DIA. n F.I.F.VATIO F,LEVATIO AREA VELOCITY HEAU F.LF,VATIO LOSS ELEVATTON LOSS LOSS ELF,VATIO ELF,VATIO HEM LOSS LOSS ELEVATION CB CB CFS FEE IN VALUE F'k:E'f FEE 5 F rT/SF,C FEE7 FEET FEE FF.F, REE FEET FEET FF.F,T FEEI' FEE EET FEE7' R1M EI. 4B 4 0.29 72 12 0.012 436A1 439.47 079 0.37 0.00 442.77 D.00 442.77 0.00 0.00 442J8 439.47 0.00 0.00 O.W 442.78 443.01 025 4 4A 0.15 28 12 0.012 439.47 440.03 OJ9 0.19 OAU 442.78 0.00 442]6 UDO 0.00 442.78 440 Ol 0.00 0.00 0.00 44278 443.03 0.25 ' SA 5 1J6 S8 12 0.012 438.00 443.22 OJ9 4.79 036 442J7 0.54 44412 O.IR 0.18 444.56 444.�,7 0.33 0.1t 0.00 444.45 447.02 2.57 5 ( 3.60 52 12 0.012 443.22 443.48 0.79 4.58 033 444.45 0.45 444.90 0.16 0.16 445.22 444.93 0.14 0.00 0.49 445.58 447.41 1.83 6 7 295 88 12 0.012 443.48 44823 OJ9 2.99 0.14 445.58 0.32 44923 0.07 0.07 44937 44'�38 0.04 0.19 0.00 449.5] 451 J0 2.17 7 B 1.31 55 12 0.012 448.23 448.30 0.79 1.67 0.04 449.53 0.06 44'I.59 0.02 0.02 449.64 44910 0.00 0.00 O.nO 44264 452.00 236 6 ? 0.74 28 12 0.012 443.4X 444.04 0.79 0.94 0.01 445.58 O.DI 445.59 0.01 0.01 445.G0 444.04 0.01 Q02 (LlH) 445.61 447.41 I.RO 9 10 O.s9 39 12 0.012 444.04 446.77 OJ9 OJS 0.01 445.ti1 0.01 447.77 uoo UAO 447.78 446J7 0.(A) 0.00 0.00 447JR � 45027 2.49 i iiiaoo ��uus LNciNLLxs,rNc. rnc�: i ,.: ,. , ,... .. ,.. �i i.�X ).Af'$�C'',t.'I�xin7'.IiN�fS . ..,. ,:...:. . .... • JOB NAD7E: F:AGI.F.RIUGE PREPARED BY: DF.CAYTON JOB NUbiBF,R: 99102 � DESIGN STO[tM: 100 YF:AIt F,NTRANCF. ENTRANCE EXIT OUTLET IIVI.N;f AYPROACII BEND JUNC110N � PIPE PIPE MANNING'S 0[ITLET INLET PIPE FLUW VELOCI7'Y AII.WATE FRiCTIO1V HGL HEAll H.N:AU CONTROL CONTROL VELUCffY HF.AD IIEAD EAQWA7'F.R - FROM TO FLOW LENGTH DIA. n ELEVA'1'10 ELEVA770 ARF,A VF.LOC17'Y HEAD ELEVATIU TASS F.I.F.VATiON LOSS LOSS ELEVATION P:LF:VATiO HEAD LOSS I.OSS ELEVATION CB CB CFS FEE7' IN VALUE FEE FEE S F7 NT/SF.0 FEE FEE FEET FF.F.T FEE FEE FEE FEET FEE FEE FEE7' FEE RIM EL 4B 4 Q34 72 12 0.012 4J8.0.7 439.47 OJ9 0.43 0.00 442.8G 0.01 442.87 0.00 O.OU 442.R7 439.4"7 0.00 0.00 0.00 442.87 443.03 OJti 4 4A 0.17 26 12 0.012 439.47 440.03 OJ9 0.22 0.00 442.87 0.00 442.87 0.00 0.00 442.87 440.03 0.00 0.00 O.UO 442.87 443.03 0.16 SA 5 4.42 58 12 0.012 43B.W 443.22 0.79 5.63 0.49 442.86 0.75 444.22 0.25 0.25 444.71 444.ti7 0.45 0.15 O.IXI 444.A1 447.02 2G1 S 6 4.23 32 12 0.0�2 44322 443.48 0.79 539 Q45 444.41 0.62 445A3 0.23 0.23 445.48 444.91 0.19 0.00 0.68 445.1G 447.41 1.45 6 7 2.75 86 12 0.012 443.4R 44823 099 3.50 0.19 44596 0.44 449.23 0.10 0.10 449.42 44).38 0.06 0.27 O.W 449.63 451J0 207 7 8 1.54 55 l2 0.012 44R.23 448.50 0]9 L96 0.06 449.G3 0.09 449.71 0.03 0.03 449.77 44920 0.00 0.00 0.00 449.77 452.00 2.23 C 9 0.87 28 12 0.012 441.48 444.04 OJ9 I.11 OA2 445.9ti 0.01 445.98 0.01 001 44h.00 444.04 0.01 U.03 0.00 446.01 447AI IAO 9 10 OJO J9 l2 O.OI2 444.04 44ti.77 OJ9 0.89 0.01 44G.01 O.ul 447.77 0.01 001 447JR 446.77 0.00 0.00 (1(� 447J6 45027 247 11/10/00 DOl�l)S ENGINGERS, WC. PAGE I ,�. , .� SECIZON 3.2 RUNOFF COMPUTATION AND ANALYSIS MEI'HODS FIGURE 3.2.1.0 25-YEAR?A-HOUR LSOPLLJVIALS ' �S ._ . - �'�� SN MOY19N COUNTY � � ��y:' �� .. � �� .� �� _�� s ♦�l��a '�� [ p . KINO COYNTY n �. 2 �t „` __ — � � •/ -�-\ ` . 2 8 @ _ � '= . u?0 , _ � � � _ ,� � � • p�5 �� " _' ': ..o..o ' � _k� .,...... '` ::� ' 3u� _ �.;i � ``= -. u?S�•'g - � ;' _ �� - ` � O .... .: " \��. t �• ..` p:u�? ' s;�t;�-.�. __. � '�w• . � �� . '. n c . �. "'" .. . _'` -. ' � .in.a f!latr � � -' '� ' � t =�_ �y . . �+..-.._ y� Vi' -_ p \ . :�cR '��:.,f--. _ " - _ _ \ ' . L s��l // `` . . . .��. t .. , .'. . ... �_. �. � �. _ � `�: _ . _ _ 5.0 ., ;. . .._ �, � ' � �� > •� ` '^i�1', � - ---�� . - .� i: $f � � �� ; , -- �� - -�\ � � �~ .. _ '� - � t3ti\,,- , � ; �� — } �_ - y.. � ��,,. ` � � r .�. fID _,_, �� -_ � �: ..�.0 � /; � �� __ � �` � ^ ,J :'JF->� _ -�' l � �� ' / _ .-� '� �� _ � �� _ ' . � ��,� _ . .0 � s #��, ;,3� • � .. _ ;/ �" a :"T/"�� _. `� �' � 4 * «�� .J �� . � S�. 5,- � - - - �� << _ _ t,.� . f 3�' . � - . . F � ��,...-` � �."��'�11 ' /�� \�\, . k�:;�' -_ •'X \ ' T . .u�� . \ - ♦ • ' ;:i• 4 . � � >�i r' er. � ♦�. ' _ ../ �_�__ _ `'�� ':a""'"�.`J . �. �.. - ~' . ♦ � ��. �o y �� -' •� .: . � �• � , � � u�vu ., _c`3 � ��.Qy��•� �KIM4 COUKTV �. �� iIERCE COUMTY WESTERN � '�_�� • �;; K1NG COUNTY `.-� - - - SS N �` _.�,, � S a 25-Year 24-Hour � � � `� 4.s� ,,• � �-_ -� , Precipitation �, � � -, �;L� in Inches °�""�� `�•�. �° � 9/1/98 1998 Surface Water Design Manual 3-16 ..• , •. ---, F:=,TI01.�� Rir"i_-3:�:�� FIGURE 3.2.1.D 100-YEAR 24-HOUR ISOPLiJVIALS ��.. ��. .�� _�� _ � COYN�v � �, �a� � N COUNTY �� w.a � � _ / `�q �: .- —�_, �.:..:, 3 ; ; u?j' � ,^ i .. 3�8 'S -a�.,�.: - '" � ,.ao � � _._ .,- ._ ., ,... ; � 4, '_. - � f Q� � _ _ -- �� ,,. �� 2 �--� « `�� . � -^`\ � ��.:..e � -- - - 43 � fv;: _ -�,.,�,--` � ,�--, sr � - , __ ; .� �Y��: .,..�. �r� t .:. , • _ �; t — - ,`\ ,. �: p ,.,�. : 'tS, - � � �;-' �' - '. '� �-` ,,p i� _ ,.,.,..,.� �`Y�. ��' !I• � p �Y+�y '� � `^ --`'S � _ ' . , \ •,_ E \.a�. � � � ' .�. . ��y J� . �1 � � � � t �}� D `\ - � r.e; � '��.� `\� h b `! \ " . -�� .� � / -. ' � - ._ RLMT�..._ . 'tb.. �i ,,�� ^-.v_�. _.._. _ _.. Jr�% ,� '� - �s '. �, I I c.� e.s � .-4r�et 5�, 4.._ �'� i:. . .e — r."� - Q, ;� : . �.\ �; `'� ' '��'"�" w.�.. _ _ � � : \ , __� O'� \ r-� � �� ;i n e O - �,$` �g� � / .\ d -' - ...a,. 1 ��T`W�• ��K•• C O CDURiY• `\\. � _ PIE G[ COYNT• J WESTERN �° `�' � '�y'�� ' �- -: � . s.s � . KING COUNTY �o ,� .}� �_� ::..�. .: s.o N 0�• cy ~,� 5.5 100-Year 24-Hour °`� �`� �.,� �' -L � 0�, y _ �,j" � Precipitation �-�� - � -� ��, , in Inches ��Miles °`' yo � L�� h 1998 Surface VJater Design Manual 911/98 3-17 � , .� V. Erosion Control Calculations The intent of this erosion and sedimentation control plan is to minimize erosion and the transport of construction related sediments off-site. This design will utilize interceptor swales and ditches to route all runoff originating from disturbed areas of the site to the permanent drainage facility,modified with the necessary erosion control measures. The sedimentation control facilities were desi�ed using the methodology as presented in Chapter 5 of the KCSWDM. This plan will also include constructing temporary filter fabric fencing along the south and east property lines and the placing of mulch, straw, chips or hydroseeding on all disturbed areas which will be exposed during the wet season as required, see plan sheet C231, note 7. Sediment Pond Calculations • Tributary area=4.2 acres • Design flow, QZ= 0.94 cfs (see attached basin summary) • SA=2 x QZ/0.00096 = 1,958 sf(required at top of riser) • Side slopes= 3:1 • Depth of dead storage= 5.0' • Depth of live storage=4.5' • Surface area at top of riser=9,900 s i� • Riser: Design flow, Q,o= 1.77 cfs (see attached basin summan�) 18" diameter riser«�ith 1 foot of head � 8.5 cfs (see attac�lle�i Fi�. �.-�.�'J) • Emergency Overflo��1 Spill�ray: Design flow, Q,�=2.71 cfs (see attached basin summan�) Overflow to be provided by the permanent structure, max. flow » 2.00cfs • Dewatering Orifice: Orifice area= :�(2h}0�5/(10.6)(3600)Tgos _ (9,900)(2)(4.5)°�5/(10.6)(3600)(24)(32.2)o.s =0.0081 sf Orifice diameter=24(orifice area/�)os , =24(0.0081/�)os ' = 1.22 inch. USE 1 inch min. �. �r •' ' 11/�4/00 6 : 51 : 16 am Dodds Engineers, Incorporated page 1 EAGLE RIDGE CORE JOB # : 99102 --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: SPOND002 NAME : SEDIMENT CONTROL POND, 2 YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4 .20 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 4 . 20 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 59 . 00 0 . 00 TC. . . . . 5 . 00 min 0 . 00 min ABSTRACTION COEFF: 0 .20 PEAK RATE : 0 . 94 cfs VOL: 0 . 36 Ac-ft TIME : 480 min BASIN ID: SPONDOIO NAME: SEDIMENT CONTROL POND, 10 YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4 .20 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2 . 94 inches AREA. . : 4 . 20 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 89 . 00 0 . 00 TC. . . . . 5 . 00 min 0 . 00 min ABSTRACTION COEFF: 0 .20 PEAK RATE : 1 . 77 cfs VOL: 0 . 65 Ac-ft TIME: 480 min BASIN ID: SPOND100 NAME: SEDIMENT CONTROL POND, 100 YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4 .20 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 95 inches AREA. . : 4 . 20 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 0� min CN. . . . : 89 . 00 0 . 00 TC. . . . . 5 . 00 min 0 . 00 min ABSTRACTION COEFF : 0 . 20 PEAK RATE : 2 .71 cfs VOL: 0 . 97 Ac-ft TIME : 480 min � � � � � .. • • ��HS��7�'��6/�! ��u��l�r��s::��JM�y �� M�� —� IaN7�r ��e��ar��+io�c� o��.v��w�� ris��a�+��l�� 1 ��a��ra��w- ��w��si��a��w� o��vo��vii��s��.�� ___—__