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HomeMy WebLinkAbout03278 - Technical Information Report - Culvert Sizing Calculations . • �� Core Design,Inc. CORE 14711 N.E 29th Place Suite #101 Bellevue,Washington 98007 � DESIGN 425.885.7877 Fax 425.885.7963 RECEIVED OCT 2 8 I�C'D PLAN REVIEW CULVERT SIZING CALCULATIONS FOR WEDGEWOOD LANE DIVISIONS 1, 2 AND 3 RE�VTON, WASHI`GTON �,� .�—r;vr�, �C. ;r ,,v�'�,ti:�� � �`'�4;` � �' � ." ' �: Prepared by: Scott Borgeson, P.E. ;� • ;�;,,, �• Project Manager: Edgar T. Jones, P.E. �" I ��� .i ''� �,�`�'.�oL� .:, •�. Core Project No.: 01045 � ^ � �F:, '1:.� r� , nrk .. Date: October, 200_5 �E:iC�PE= `1—2^—.�'i i ;^,�; /`/ ,✓ ��—iJ� ENGINEERING PLANNING � SURVEYING '�,3 Z 78 � I WEDGEWOOD LANE �, TABLE OF CONTENTS I. Project Overview II. Culvert Sizing Analysis III. APPENDIX Core Desi�n. Inc. ��`EDGE��'001)L:\NE P:ihc I � � _ � I. PROJECT OVERVIEW � The Preliminary Plat of Wedgewood Lane is located in the city of Renton, East of 142°a 'I Ave. SE and south of N.E. 10`t' Street. Please see the Vicinity Map on the next page. I This project site includes multiple parcels that currently have approximately 7 single- �I family residences and associated garages and outbuildings. A Type II Wetland runs just ' outside of the eastern property line along the majority of the property. There is a seasonal � stream that cuts through the northern portion of the property. The existing ground is covered with tall grass and forestland. The property's eastern boundary borders the proposed plats of Rosemonte and East Renton and other undeveloped parcels, all of which are in King County. On the project's western boundary are two proposed plats, Aspen Woods by Harbour Homes and Cambridge Lane by Cambridge Homes (a.k.a. Rutledge Property). Please see the Existing Conditions Exhibit at the end of this section for a visual depiction of the existing site. The final plat will be developed in three divisions. The adjacent preliminary plat of Cambridge Lane will be developed separately, but the stormwater runoff from it will be tributary to the Wedgewood Lane stormwater system. We are designing the stormwater detention and water quality facilities to serve all three divisions of the Wedgewood Lane project, as well as the Cambridge Lane project that is currently being reviewed by City staff. The two stormwater facilities and associated best management practices proposed as a part of this project will be designed to comply with the 2005 King County Surface Water Design Manual (KCSWDM). Specifically, Level 2 Flow Control (stream protection standard) and Basic Water Quality will be provided. 1 ure Tle�i�;n. Inc, �1i U(:E���OO[) L.-1i�'h� }':i�e 3 �_ j I I I I M� � �i , �� i I, =J^ v I y �I i j ! � � L I 5L`p. � ; � �� 'vNcE� g0} \ '� ��` i AE 'SS�C�QN c"I c- ^.r� �� .Nt��� ,�I 1 ;iJ � - - i z c-_ -� r` II w � � 9CC � Q � �� � �r � Nt 10�H JT. �I _ -� _ " � I ����� _ # ,�_�451� � � ��J� Z y � � - �����' I j Z i � / ; ! Q '�I � .-, .G I a s > � �: I 8 i o� Z � < � ' � i Z � a _ `�� sI I 1: c I Z � �' =I C . 'I �i � � ,� � R � N � CN M'� a° <� , ��� �I Z � ���� �i �I �= '' �i '%��- � NF 4T'r � i _' � I j� � ,� � � �U �U�?� . j �' f�% � 1�` 5\ i '� � � iK�i L�..-�V� j Ili � ��%�i` N� � � ��� I �/ i �,��E�ti=;;��� I ; =If , ���� � �; �=��T��Y � , �� ; �i � I f�r� �? �pl �0 � �� � �4I III \ �� . I � i � � I I �\ ,. �� I � I � '�\��\F �-� ; I � �\;11\�:d(�F� ! i, � c„ . %F,.,� '� I �fw�:_=�il�v, . . j'. . � . . ..\ ��_ ��_��-- . VICINITY MAP Not to Scale i� I ('�u•e Desi�n. Inc. ��T•:D(;F:��'l)f)D 1,.4�1E Page 3 II. CULVERT SIZING The following analysis is provided to document the verification of the sizing of two culverts on the Wedgewood Lane project. One is proposed far the crossing of an existing stream under the proposed plat road of Jericho Place N.E. The other is an existing culvert, which will be extended as a part of required road widening improvements on N.E. l0ih Street (also known as S.E. 116'n Street). The tributary areas for each culvert were determined as shown on the Culvert Tributary Area Exhibits at the end of this section. The exhibits also show the time of concentration flow path used for calculating the flow rates tributary to each culvert. The computer program ' Waterworks was used for the flow calculations since it allowed more accurate modeling of the attenuation that stormwater will receive as it flows through the densely wooded wetland system that comprises a large percentage of the basins. The land coverage information was determined from site visits, city topographic maps and aerial topography. Most parcels were modeled in their existing condition. However, plats that were developed in the last approximately ten years, that drained to detention ponds, were modeled as grass, since these ponds will detain the stormwater they receive to approximate a grass or forested condition for their discharged flows. Plats that are currently proposed were modeled as forest, since the detention systems that they will be required to construct will release stormwater to mimic the existing forested condition. The areas of each land coverage type are summarized in the tables below and additional detail is provided at the end of this report. The Waterworks program output is also included at the end of this report. CULVERT TRIBUTARY BASIN SUMMARY - �'.E. 10th .T���^hc Street Place Culvert Culvert Basin Basin Area Area (Acres) (Acres) Till- Forest 81.6 3.15 Till - Grass 53.3 18.02 Impervious- 221 7.83 � Streets, SW, Roofs, etc. - - _ �. Total 157.0 29.0 ' ��. _ � -_�R�. �,. ���,. _�,.���.�.. . Time of Concentration - Pervious 100.2 min. 64.7 min. Time of Concentration - Impervious 10.0 min. 10.0 min. - � 100-year �low (Qloo) 37 cfs 10 cfs ('��re I)e�i,�,��i. lnc. �1�f;114;�1��1)Ill` I..-�\E ���� With the flow rates calculated for the 100-year storm event, Figure 4.3.1.B of the King County Surface Water Design Manual was used to determine the headwater to depth ratio (HW/D) for each culvert, as both were sized for inlet control. The figure is included at the end of this section. The headwater depth for each was then calculated as follows: N.E. 10�h Street HW/D =2.80 ', HW=HW/D * D=2.80 * 2'-diam. = 5.60' �� Therefore, the headwater will reach an elevation 5.6' above the 24"-diamter culvert's invert. The �li extension of the existing culvert is proposed to have an invert elevation of 414.36 and therefore, '� the headwater will reach an elevation of 419.96. At the completion of this project, N.E. 10`�' I Street will have a minimum centerline elevation of 421.31, which is comfortably above the ' headwater elevation for the 100-year storm event. Therefore, this existing culvert and it's extension will not cause flooding of the road. A rockery that will be constructed to at least 40 feet on either side of the culvert will help maintain the stability of the road bed when large storm events cause the water depth in the wetland to rise. This analysis is inherently quite conservative, as the calculations of the peak flow rate for this basin do not adequately account for the attenuation that the relatively flat and wooded wetland will provide to naturally slow the stormwater flow rates provide evapotranspiration. Jericho Place N.E. I�'' HW/D = 0.91 �� HW=HW/D * D = 0.91 * 2'-diam. = 1.82' Therefore, the Jericho Place culvert's headwater depth would be approximately 91% of the pipe diameter, which shows that the selected 24"-diameter culvert will have sufficient capacity for this location. Core Design. (nc. ���F'!►t:E���1)Oli I_.1�E Pa�c ;� III. 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(� • • • ", ,� .� . .... . 1 • • • , � r I� . • • • � � � ..._. � n c � � m O � '` o "� m �� � � _�/ � Z O N v z � � '�'1 � � � D " N � y � � z � � O Z � ga g a �/ c� �� = II � � QO m � � � � � o � e � � � A �� � � - ; acn � � .� m � y � < � � a � � Z � � � 10/21/05 11:44:34 am Core Design, Inc. page 1 WEDGEWOOD LANE - CULVERT SIZING --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: lOTH100 NAME: NE lOTH CULVERT 100-YR SBUH ME'I'HODOLOGY TOTAL AREA. . . . . . . : 157.00 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3.95 inches AREA. . : 134 .90 Acres 22.10 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 83.00 98.00 ' TC. . . . : 100.20 min 10.00 mir. ABSTRACTION COEFF: 0.20 PEAK RATE: 42 .67 cfs VOL: 32.06 Ac-ft TIME: 480 min BASIN ID: JER100 NAME: JERICHO CULVERT 100-YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 29.00 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .95 inches AREA. . : 21.17 Acres 7.83 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 85.26 98.00 TC. . . . _ 64.70 min 10.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 12.07 cfs VOL: 6.72 Ac-ft TIME: 480 min --------------------------------------------------------------------- --------------------------------------------------------------------- - -- - - ---*.�•.*�,r.v PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf\AcFt Acres --------------------------------------------- --------------------------------------------- 1 42 .665 480 1396330 cf 157.00 2 12 .070 480 292785 cf 29.00 �_'���ir �)�,sien. ln� �11�:41(;F11'l)(ll) I_�1�F F;!��,, I IL . ��- z �r � �L/�vC��v�c�i ri�-�.E /I/. 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" �` \� i r 4 �' .� �.Ru . 3 .�� ` _�'-" .d ��:. �aJ�� - ,�„�.. �:- " _ �e �1 ^;..r._ µ �. �\ ��•� .._ ��'M'� . � � 4 O am•a Y� 4� .: , ��� • y �2 " ,_„� - .. � ,.,o,. = �� � �� �� � _. — 'j� ��� ' _ _ _ ��� � _ L_ , .�. 1 r c:^ � ' (� . ' �� , - '�" � \ , _ � . i♦ . -_ �'�. � � /( �-A _ V" ' Q r �� M ��^ ..� '�i�^- . "� . . > ' wj--��-1. � �`t - - . �. � ~ µ��. _ .., \ . - �- , `� ' :l `J . � `� . . . _�. � . � . i.i. . -- �..�� �,4s ``\ r/ \ . � �,:�_ ' �..._.f� `� � �,\ / � � •> � • .e - -``• — _ �,'i _ :r.;a '� :�:?.. . . - ' �-:.a�. '�sc�:�. 3:� � � "'=�" ' o� :'� . _..... . i`. � ,_ � . '. Y ',,[../�� ' c .r� (� ww ':.-. r�•( Y °Ai , t. i++aw . . �'`" S` 'i �t-� � � ' - - � �' : t ��''" ' An Q�F ' ` � . ` '" 3 \ f' m. � _� '_ 1� � \ -- " :�.�.:. f � �' ' 6� c� �—� • ',1 r%�"� �, O .� � �', � � ,� . ��.� � �_ � � ._� �_ - - � \ ,� c..�.., �� �, � a. ' � .;___� �: rw�n ^ O.COJJMTY '� LF ��'� ` ilE CC COV1/i► ��� WESTERN o° `� � '`_'' � `�' ��' s.$ � KING COUNTY �,o ,, .�� -����:- :., s.o N p,. � • - .. < �, 5.5 ' 100-Year 24-Hour °�� �:� �.� � �f.�� � Precipitation °`��,y -, ,-;�.� '' yo � L, in Inches °�"� � } y. I998 Surface Water Design Manual 9/1198 3-17 , STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN Table IIZ-1.3 SCS Western Washinqton Runoff Curve Numbers (Published by SCS in 1982) Runoff curve numbers for selected aqricultural, suburban and urban land use for T lA rainfall dietribution, 24-hour atorm duration. LAND USE DESCRIPTION CURVE NUMBERS BY HYDROLOGIC SOIL GROUP A B C D Cultivated land{1) : winter condition 86 91 94 95 Mountain open areas: low growing brush & qrasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or foreet land: undiaturbed 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover cro 81 88 92 94 Open spacea, lawns, parka, golf coursea, cemeteriea, landscaping. Good condition: qrase cover on Z75$ of the 68 80 86 90 area Fair condition: grass cover on 50-758 of 77 85 90 92 the area Gravel roade & parking lota: 76 85 89 91 �� Dirt roads & arking lote: 72 82 87 89 I Impervious surfaces, pavement, roofs etc. 98 98 98 98 en water bodies: lakea, wetlanda, onds etc. 100 100 100 100 << ,v �-, ,,- ��_:�=i�l(2) � __^�__ �__j __.._ . Dwelling Unit/Grose Acre $Impervioue(3) Separate curve Yiumber 1.0 DU/GA 15 shall be selected for 1.5 DU/GA 20 pervious & impervious 2.0 DU/GA 25 portions of the site 2.5 DU/GA 30 or basin 3.0 DU/GA 34 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 PUD's, condoe, apartments, $impervious commercial busineseea & must be industrial areas computed (1) For a more detailed description of aqricultural land use curve numbera refer to National Enqineering Handbook, Sec. 4, Hydrology, Chapter 9, Auqust 1972. (2) Aasumee roof and driveway runoff is directed into street/etorm system. (3) The remaininq pervious areas (lawny are conaidered to be in qood condition for these curve numbers. III-1-12 FEBRIIARY, 1992 I . ' IIIII STO�MWATER MANAGEMENT MANUAL FOR THE PUGET S�UND B�SIAi � Table III-1.4 "n" AND "k" Values IIsed in Time Calculationa for Hydrographs I "n�" Sheet Flow Equation Manning's Valuee (for the initial 300 ft. of travel) n, I Smoot eur aces (concrete, asp alt, grave , or bare hand packed eoil) i 0.011 i Fallow fields or loose soil surface (no residue) 0.05 Cultivated soil with residue cover (s5 0.20 ft/ft) 0.06 Cultivated soil with residue cover (s> 0.20 ft/ft) 0.17 Short prairie qrasa and lawns 0.15� Denae qrasses 0.24 I Bermuda grasa 0.41 i Range (natural) 0.13 ! Woode or forest with light u�derbrush 0.40� Woods or forest with dense underbrush 0.80 *Manning values for aheet flow only, from Overton and Meadows 1976 (See TR-55, 1986) "k" Values Used in Travel Time/Time of Concentration Calculations Shallow Concentrated Flow (After the initial 300 ft. of sheet flow, R = 0.1) k9 l. Forest with heavy ground litter and meadows (n = 0.10) 3 2. Bruahy ground with some trees (n = 0.060) '.5� 3. Fallow or minimum tillage culti��ation (n = 0.040) 8 4. High grass (n = 0.035) 9 5. Short grass, pasture and lawns (n = 0.030) 11� 6. Nearly bare ground {n = 0.25) 13'' 7. Paved and gravel areas (n = 0.012) 27 Channel Flow (intermittent) (At the beginning of visible channels R = 0.2} k� , _ p.,Yeet�� �..��'_:.. --}k �� _ ---'`' -- `-_ ._ ;n = 0�1�' . 2. rorested drainage courseJravine with deYineu channci bed (n = O.c�50} 1� 3. Rock-lined waterway (n = 0.035) 15 4. Grassed waterway (n = 0.030) 17�. 5. Earth-lined waterway (n = 0.025) 20 6. CMP pipe (n = 0.024) 21 7. Concrete pipe (0.012) 42� 8. Other waterways and pipe 0.508/n Channel Flow (Continuous stream, R = 0.4} k� 9. Meandering etream with some pools (n = 0.040) 20 10. Rock-lined stream (n = 0.035) 23 11. Grasa-lined atream (n = 0.030) 27 12. Other streams, man-made channels and pipe 0.807/n** III-1-16 FEBRUARY, 1992 . 43.1 CULVERTS—METHODS OF ANALYSIS FIGURE 4.3.1.B HEADWATER DEPTH FOR SMOOTH INTERIOR PIPE CULVERTS WITH 1NLET CONTROL 180 1 U,OOQ �ss s,poo EXQMPLE �1� �2� �3� ENTRANCE TYPE 6. 156 s��� o=a2�nd�es (3.o teet�. 6. a=�2o ds , $, S(]UARE EDGE WITH �qq $+�� HEADWALL 4,000 Nwr r+w 6. 5. 132 ° ���� �. 4. 3,000 ��� 2.s s.a 4. 120 �� z.� �.a I 1 � 2,000 �s� 2.z �.7 4. I 1 '108 3� • ro in ,eec N(,�/�: s. . . � '7 3. � PLAN �1� 1,000 G'� GROOVE END WITH 800 ___.. __y HEADWALL g4 / 2. 2_ �,�;,: b00 °' 500 �/ 2. � ;,I. . � 400 0 � � � = 300 �j/ = 1.5 1.5 I ._: Zgp V 200 �/ W 1.5 �'�� PLAN �2� — Z � W GROOVE END � 54 � � Q PROJECTING ~ v 100 � > 48 �/� 80 Z �, � _ � � S �0 ~ ,_^ 1 �J i _> �� � �� 9M � HW ENTRANCE o . � Q ��� � � 40 p SCALE TYPE p� � 36 30 ��� Square edge with a - ` (3) � � head � '9 a 20 (Z) roove end with W 0 hsadwalt = •$ ,$ 30 .8 Hw/o= o.�l (3) Groove e�d � projecting �� .7 7_ 4 8 •7 6 To use scale (2J or(3) projeet 2,� 5 horizantally to seale (1}, then � 4 use siralght inclinad Iine through D end 0 acalos, or rtverse u •6 .6 3 iilustrated. .6 18 2 15 .5 � 1.0 .5 12 1998 Surface Water Design Manual 9/1/98 4-43