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HomeMy WebLinkAbout03116 - Technical Information Report - Drainage � . STORM DRAINAGE REPORT PROPOSED HIGH AVENUE SHORT PLAT 520 HIGH AVENUE S. SE '/, OF SW %4 , SECTION 17, T. 23 N, R. 5 E. W.M. RENTON, WASHINGTON 98056 i RENTON LUA-03-024 � CITY OF RENTON RECEIVED M,�Y Z 5 2Q03 CUSTOMER SERVICE FOR: Mr. Marc Roussu �735 NE 4`� Street kenton, WA 98059 May, 2003 ��� � �. �cy: t7 ��w �.p. Yrepared by � �� � Touma Engineers � ,; � ' 6632 S. 191ST PI, Suite E-102 -� � "="� p� « �� Kent Wa. 98032 sa��: �� .,-;. �� � , . PEI. 425-251-0665 . '�9fi�, -�> / ;-=;', '�, �.,,,��;is •�.,::,��' Nax 42_5-251-0625 � �- _>���F��..�'.',� '�i�s-��;'�� �__ic.1F'i�:��:��/�:'/�5,.___. .,� JO13 NO. �31i-01}1-OU2 �v__,_�__.___...� .. , 3 ��� 'I,A13Lt? t)F CONTF.NTS I'a�es 1. NROJECT OVERViEW 1-� II. CON1)ITIONS & REQUIKF.MENTS SUMMARY 5-6 lll. OFF-SITE ANALYSIS 7-8 IV. FLOW CONTROL & WATER QUALITY 9-13C V. CONVEY�►NCE SYSTEM ANALYSIS AND DF.S�CN 14-18 VL SPI��('IAL 111�.POR�CS AND STUDIES 1�1 VII. [3ASIN AND OTHER COMMUNITY A1tEAS 20 Vlll OTHf+�R PERMITS 21 IX. EROSION/SEDIMENTATION CONTROI. DESIGN 22 X. BONU QLIANTITIES WORKSHEET 23 XL MAIN`I'ENANCE & OPERATIONS MANUAL 24 . � ir-� � ���'� . �fr I. PROJECT OVERVIEW `I'his project involves a single parcel of approximately 0.716 acres. The project is situated in the east end of the City of Renton. It is located within southeast quarter of the southwest quarter of Section 17 "Township 23 North, Range 5 East W. M. The proposal is to create 4 lots, "Pill in" su�iivision. Access to the proposed project will be via a public road from High Avenue S. for lot 1 and a private road tur lots 2 ihrough 4. The existing house, patios, carport and garage is on the site presently and will be removed. F�our new houses constructed on the four lots that are �en�rated with this short plat. "I hc; site is bounded on the east, and south with developed single family houses. A public street lies to the west, High Avenue S. "l,hz soils on the site are composed of Indianola (InC) gravelly and fine sand per the King County Soil Survey. The Indianola series is made up of somewhat excessive drained soils that formed under conifers in sandy, recessional and stratified glacial drift. This type of soil is designated by King County as Type A soil and is good for infiltration 5ystem. A geotechnical report prepared by Icicle Creek Engineers states that the soils are glacial till (dense silty sand with gravel), glaciofluvial (stream) sand and gravel, glaciolacustrine (lake) clay and sand, and non glacial clay and sand. The geotechnical repurt recommends that each house install perimeter perforated footing drains, tightlined away from the houses and the adjacent steep slope. The report further states that the roof drains be connected to a tightline drainage system. The site is rolling for most of the area with an average slope of 8 percent. There are steep slopes greater than 40 percent beginning along the north margin of the site that slope down to the north. Z'he geotechnical report prepared by Icicle Creek Engineers recommends that building foundation fooi ings be setback thirty feet fiom the face of the steep slope adjacent to the site on the north. The surface runot�flow from the site is oriented from southeast to northwest directing sheet flows to tlie storm drainage system located in High Ave. S. The existing sheet flows on the east portion of the site are recharged into the ground. The proposed development ofthe property is considered as "infill" project and it is located in a Single Family (SF) zone, R-8. The City of Renton designates the site with the SF zoning. The SF zoning allows for a minimum lot size of 4500 square feet and a maximum density of 8 uniis per acre. The setbacks allowed in the SF zone are as follows: front yard setbacks, 20 feet; rear yard setbacks, 20 feet, and side yards setbacks, 5 feet on all interior lots, and 15 feet on corner lots. "1'he City of Renton Comprehensive Plan designates the site as Single-f�amily ReSidence, which is consistent with present zoning. , The density tor the developed portion calculates at 5.6 dwelling unit per net developed acre. "There is no right of way to be deducted from the site. The proposed lots will be served via a 20- feet paved private road within a 26-foot easement. Pg. - 1 i - Grading will be limited to construction of private road with supportive cut an fill slopes. 1'he quantities of till tbr ihe private road and roadway improvements on the private street is e5timatea tu be 400 Cu. Yd. Additional grading and excavation is anticipated when the new homes are constructed. The site contains an existin� house, garage and asphalt driveway. The existing impervious driv�way surface subject to automobiles is 2800 square feet, and totals 8,260 syuare feet impervious surfacing. The remainder is landscaped primarily as lawn. In the developed condition the impervious surface is estimated io contain 13,120 square feet impervious, about 5200 square teet subject to automobiles. The total new impervious surfacing is 4,860 square feet and the total new surface subject to automobile is 2,400 square feet. "There will be no land that will required to be dedicated to the City on this project. RF,VIEW OF RESOURCES 1. Vicinity Map 2. King County Soil Survey Mapping. 3. 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CORE ANU SPECIAL REQUIREMENTS CORI: REQUIRCMFNT'#1: DISCHARGE AT NATURAL I.00ATION The allowable outflow trom the site will be discharged to its natural tocation at the north end of High Ave. S. CORE REQUIREMEN"T'S #2: OFF-SITE ANALYSIS Reter to of�=site analysis on subsequent pages. COItL; REQUIREM[;N'I'S #3: Rl1NOFF CONTROL Calculations are provided on subsequcnt pages addressing peak runot�: Sizing for peak rate runoff conirol facility and its rouiin� do not appear to be required. Water quality control does not appear to bf; reyuired based on less than 5,000 square feet of new impervious surfacing subject to tra�ic. Initial calculations indicates tllere will be no detention facility required because there will be less than 0.5 CFS increase t��r thc100 year peak. Please refer to attached calculation at the back of this report. CORE REQUIREMENTS #4: CONVEYANCE SYSTEM The conveyance system will be designed using the rational method. GORE REQUIREMLNTS #5: EROSION/SEDIMENTATION CONTROL PLAN The I:rosion/Sedimentation control facilities will consist of filter fabric fence5 to be placed along the northwest and north margins of the site. CORE REQUIREMIiNT#6. - Maintenance and operation 'I Maicitenance involves having on-site catch basins cleared hom scdiments when necessary. CORE REQUIREMFN"f #7. - Ronds and liability SPECIAL REQUIREMENTS: THOSE AYPLICABLE TO PROJECT l. Critical Drainage Area - "The drainage basin is not part of any critical drainage area. 2. Compliance with existing Master Drainage Plan—N/A 3. Conditions Requiring Master I)rainage Plan—N/A � 4. Adopted Basin or Community Plans—N/A, However, the site is drains to The Cedar , River via the 1(iba density polyethylene pipe at the north end of High Ave. S. S. Special Water Qualiiy Controls—N/A. � Pg. - 5 6. Coalescing Plate Oil-Water Separators—N/A 7. Closed Depression— N/A 8. Use of Lakes, Wetlan�is, or I)epressions for Detention—N/A 9. l�elineation of 100-year Flood Plain—N/A l 0. Flood Protection for 'I�ype 1 and 2 Steam—N/A - 1 1. Geotechnical Analysis and Report—Geotechnical study was prepared in conjunction with this application by Icicle Creek Engineers and reviewed by City of Renton staf��for the Preliminary shori plat submittal. I?. Soil Analysis and Report —Geotechnical report has been prepared for this site and addresses the soil classitications and stability. 13. A Wetland Mitigation Report - NIA. Pg. - 6 111. OFF-S1TE ANAYSIS A: UPSTREAM ANAI,YSIS 1�his proposed short plat does not have appreciable off-site runoff entering the site. The large house to the south has a wall with drainage directed to the storm system in High Ave. S. The pro�erty to the east, (Renton Co-Operative Coal Companies Acre Tracts No. 1 portion of lot 32) is serviced with an existing 12' asphalt driveway. This 12' driveway intercepts most of the offsite run��t�and directs the tlow to the drainage system in I�igh Ave. S. No surtace water was noted to enter this proposed site from the east or south. B: [)OWNSTREAM ANAI,YSIS I�he surface drainage trom the site and existing house and garage is directed to individual roof downspouts and the storm system. 1'he existing asphalt driveway area surface flows to the street and drainage system. An existing catch basin is adjacent to the site at ihe southwest corner of the site. A 12" conveyance pipe is located along the west side of High Ave. S. that directs neighborhood runoffto the north end of the street. A iype 2 - 48" catch basin is located about 100' south of a sharp drop off toward the Cedar River Valley. Flowing out of this catch basin is anchored l 5" polyethylene fusion welded pipe. The outtall �nd of�the pipe was not observed down the slope toward the valley floor. i l hcr� was no cvidence of ditch washing or erosion along High Ave S. Pg. — 7 � � -� . .__ � ' �� ., � � '�. { � � � � � � � �'��� ( ��� ���, 1'�,, � � , � � � , , I . � �t . ,��. � �' �� �� ` � ` �,��� , --X-_O____ `I �` �� \ ��� -X- - '�.`� � � � I � �� ��� ,. �� ��� � � � � J C7 ; � �,1�, ��\ � X 52 \ \. \ `� �;'� 1 � � � G �7 i " � � `��< <' � � q ��=� • ,� �� �-J - �� / R �l� V ;t 4 p � � �'. ,�, i�" - �I 11 N ��!�� s � � ;�� U ��� � � � � i ; , � o �) � � G � � • � � ,�O ;� � ��,� � ��__ _ ���� _ �_) � r� � � � �.� i �� �� �`,. ��,� � �.. .� , , /�,i � � � �� �. _ -� � �,_� �� � `y � n , C�' ` N� -- �,. ���----,-�----=� � � �� � �, , �,�_____--- ; \� , � �/ --���-� J , ` \ 1 ' ' '..,�' , T c�. � � \ � l �l � `\ \\_ �� ,��� "��/ � � ( \ ��� / � '� �'"� � c� �O ��� \\ �\ � I � � ��. � �� � �� � ��� Q � • � � �� /: /� � � � � j Y -�" ' 1 , � / � ��/� � x ��� ��', •.T R E E S ��� � �� �� x � , ;�/ � '/LJ I\� � �\. _\\� `�, -_-f;� `'Y� � � � � -- � �� l , � ; _ � �� / �cl \ , , - "� + i �x � �,r �- �( �,\ ,� �, �� �, //�`� ,, � J ' � �r ��,,I � � IS ND � ' ; �,�� � � � � � ; I � � ` \ ' \ � x- - ' /� ` .,, � I � ��'� �j S �' `'-, �s°��'`s`�°o ; ,' so �--x - _ \ X�� � i l ` - - - �' S l 1 � 28 I � X 332 � (r" r � � 1 - ' � '��� �/� I , f I L � x i I I I! �s�9 �� 3��� � � r� - - .� � - � ❑ � � �i / �_-x--- _ - -- ; �s ,,.., �' _ -�+?� �`-x -- ti N / �h I � I rL� t`� / � = �, _� ti � � u �' I ( } x - - --k � I C7 ❑ N � -.p;� �/ _ ,�-��,- .� � � � � � �`� i �� � i C� ►-i �,-� r i� � . �--—- `� __ , /CJ/ � � --�- ------�`_ i I , � �� i .�,., (� . , ) I � F. { �,�../`-� � � / I I I � �-'"_'�—J � � � �r-_ �, ,5� �� �i I�� i - -x- — � I �� ��zl �h ❑� � ,��. � � ', �O'+ . � I � � II la� I f � � O � r I j II I�i i ❑ t� i ,� �� � I i � Ii ❑ I� i� � � ���; �% � i l 0 i i ��.., ' il i i '� ��; F� � O � ; � � . � � � � �I I I QII ❑ � � � \�.\ I � � �I � � II _) � _ _ � '� � � • i L � , , � X3 7 T H - - 9 X VE. -- _ X --- _ -� \X: ) S.E. _ � i I� ; ( � , -- - r-- - - -- � -- ___ - _�`�`�_i i� �� I � II I I �, � � r-, � �`7� ` - =,z- f,�?�l Op _ '� . N I 75,93�.16 = Z� N P� v � E 1,663,214.Es7 • r� � cD . IV. FLOW CE3NTROL ANll WATER QUALITY �l�he Preliminary Report to the Hearing Examiner for hearing April 8, 2, 2003 states that this proposal should comply with the 1990 KCSWDM for drainage and temporary erosion control plan�. The area of ihe plat to be developed is 0.716 acres, including asphalt paving, driveways, houses and landscapin�. There is no new added right of way or frontage improvements required along High Ave. S. The new adc�ed asphah paving along the joint use driveway will be about 2900 square feet. Each of the four new houses will have 720 square feet of driveway. The roof runoff fron� the new houses will be directed to the tightlined storm system per the geotechnical report prepared by Icicle Creek Engineers. 1're-Ueveloped Conditions Pervious Qrush, "(�rees, l.awn 14,371 SF 0.53 AC. Cn=68 Impervious Driveway/parking 2800 SF House, patio 5460 SF Total 8260 SF 0.19 AC. Cn=98 Yost-Ueveloped Pervious La�m & Landscaping 15811 SF 0.36 AC. Cn=68 lmpervious House Roof(4x2400) 9600 SP Asphalt Road 2900 SF Driveways 4x(30'x24') 2880 SF Total 15380 SF 0.36 AC. Cn=98 The King County Hyd. Progran� was used to calculate the hydrographs ior this report. 7�he � hydro�raphs indicate that there is Icss than 0.50 cfs. increase (0.42 —0.29 = 0.13) for the l 00-year peak flow between the Pre-developed and Post-developed conditions. See page 1.2.3-5 of the King Cpy}�ty Surface Water Design Manual (KCSWDM), for negligible peak runof�rate increase. ; No runof�control is required. Pg. - 9 WATER QUALITY This short plat will not generate more than 5000 square feet of new impc:rvious surfacing subject to automobile traffic. See the areas calculated above. Predeveloped driveway and parking for existing house 2800 SF Post developed New road surfacing 2900 SF New driveways (4) 2880 SF Total 5780 SF New additional surface subject to traffic 5780—2800 = 2980 square feet. Therefore no biotiltration or water quality features will be required. i I I'�,. - 1 U 1 S . C . S . TYPE-lA RAINFALL DISTRIBUTION ENTER : FREQ(YEAR) , DURATION(HOUR) , PRECIP( INCHES ) 2 , 24 , 2 ---------------------------------------------------------------------- ******************** S.C . S . TYPE-lA DISTRIBUTION ******************** ********* 2-YEAR 24-HOUR STORM **** 2 . 00" TOTAL PRECIP. ********* ---------------------------------------------------------------------- ENTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN N0. 1 . 53 , 68, . 19 , 98, 6 DATA PRINT-OUT : AREA(ACRES ) PERVIOUS IMPERVIOUS TC(MINUTES ) A CN A CN . 7 . 5 68 . 0 . 2 98. 0 6 . 0 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 09 7 . 67 1597 ENTER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: 1PRE2YR SPECIFY : C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP C ---------------------------------------------------------------------- ENTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO . 2 . 36, 68, . 36 , 98 , 6 DATA PRINT-UUT : AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES ) A CN A CN 4 r;ts . 1i � �)8 . U o . (� t�r;A1< i,)( C'r''� ) 'i'-PEAK( t1kS 1 VOl,( CU-r"1' } . 17 7 . 67 2572 ENTER [ � , t t, ; r � . f;n ��i�� i _ _., � , i�„f� , ,)1tAr,1�, ir �)'-ti��l�l�l�,�i . , i;�;,, ,t�:-,� !i 1DEVZYR SPECTFY ` ' ll �� � 10 , 24 , Z�. 9 ---�------------------------------------------------------------------ ******************** S.C . S . TYPE-lA DISTRIBUTION ************�******* ********* 10-YEAR 24-HOUR STORM **** 2 . 90" TOTAL PRECIP. ********* ----------------------------------------------------------------------- ENTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN N0 . 1 . 53 , 658, . 19 , 98 , 6 DATA PRINT-OUT : AREA(ACRES) PERVIOUS IMPERVIOUS TC{MINUTES ) A CN A CN . 7 . 5 68 . 0 . 2 98 . 0 6 . 0 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT ) . 17 7 . 83 2948 ENTER [d: ] [path]filename[ . ext] FOR STORAGE Or' COMPU�I'Ell HYDr?(�i��P.t�H 1PREl0YR SPECIFY: C -- CONTINUE , N - NEWSTORM, P - PRINT, S - STOI� C -------------------------------------------------------. ENTER: A(PERV) , t r.,: � ,. ,,, . - ,.,-. -., . 36, 68, . 36, 98 � A (:N A (;N . 7 . 4 68 . 0 . 4 98 . 0 6 . 0 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 27 7 . 67 4239 ENTER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: 1DEV10YR SPECIFY: C -- CONTINUE, N - NEWSTORM, P - PRINT, S - STOP El , � �1 , J 1 � S .C . S . TYPE-lA RAINFALL DISTRIBUTION ENTER: FREQ(YEAR) , DURATION(HOUR) , PRECIP( INCHES) 100 , 24, 3 . 9 ---------------------------------------------------------------------- ******************** S.C . S. TYPE-lA DISTRIBUTION ******************** ********* 100-YEAR 24-HOUR STORM **** 3 . 90" TOTAL PRECIP . ********* ---------------------------------------------------------------------- ENTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 1 . 53 , 68, . 19 , 98 , 6 DATA PRINT-OUT : AREA(ACRES ) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN . '7 . 5 68 . 0 . 2 98 . 0 6 . 0 Y�:AK-Q(CFS) T-PEAK(HRS ) VOL(CU-FT) . 29 7 . 83 4725 ENTER [d: ] [path]filename[ . ext] FOR ST�RAGE OF COMPUTED HYDROGRAPH: 1PREl00Y SPECIFY : C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP C ---------------------------------------------------------------------- NTER: A(PERV) , CN(PERV) , A( IMPERV) , CN( IMPERV) , TC FOR BASIN NO. 2 . 36 , 68, . 36, 98, 6 ATA PRINT-OUT : AREA(ACRES ) PERVIOUS IMPERVIOUS TC(MINUTES) A CN A CN . 7 . 4 68 . 0 . 4 98 . 0 6. 0 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) . 42 7 . 67 6282 NTER [d: ] [path]filename[ .ext] FOR STORAGE OF COMPUTED HYDROGRAPH: 1DEV100Y SPECIFY: C - CONTINUE, N - NEWSTORM, P - PRINT, S - STOP �)�� . `"� �-.� r ' KING CUUNTY, WASHINGTON, SURFACE WATEK DESIGN M ANUAL FIGURE 3.S.1C 2-YEAR 24-HOUR ISOPLUVIALS ` ,�._ �' ' :,� _ =6� �-_ -___ ��. � ��� " �1 � '_` _ �, � � � .7 1 , ` —_ 1� V� ,,Y�., � G � ( � � • � ; - - - .. ra� - ��, � ����� ; �` � � <, r ` _�� i ��- - ;' ,r -- �' � ��1 _ -,�-�� _ ___ �s� , � � ��� ",i � _� -, �.� . r r.� - - ��i�� .f�ewu..l E - ���� 1 , �� f — y - .� �r--� - p .. ���� ...\I' � �. r� ,� ' .,! , .- '� � �. `f c�i-. 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Z � � ,� � _ . � �� Py s 'j�- 4,; � �. �j• ��� � ' _ _.� ��� .__.__•� '� . `�. � .�_ ,� ( •r ��` i Lw �f � \ . .�.1_ � _� — � �, .,, � ti+..� .. :�� ���ir i ti-�" --.� . �.,� , .'� �/� ; �� + �;, .� � �\�� � p +y f �.. / Y � - LL( ��� . ._. _ -.` � ' .._.' ) A�� � �� � _ � Z,� 1�/� 1 ' , ` .34�� � ... _ _ _ _ - - - — � - � t� .. � , I � � 10-YEAR 24-HOUR PRECIPITATION � �: _ �o���R � 3.4�"' ISOPLUVIALS �F 10-YEAR 24-HOUR �'� � ' _� °�� � TOTAL PRECIPITATION IN INCHES ���� ". � _. t` -� �C _ _ ------ -- --____ C� � .: ,' - 0 1 2 3 4 5 6 7 8 Mlles --- �i/ — f� � � � `''!� W� =I, � �� ;,I i: soo,onn 3.5_1-1(1 � 3�LJ "� l�qO 40 , i � , . � , � ��T : ��,•`� ��: ► �r _ - v r ,� , . _� `, . . �il��@ , � ' " ��� , � �, . �� / � � � ' • ���M�� � � � � � ���������� � •�•�� �- ` � � '��!�����r ,� - `''' � '.., � � d�� � � ����:'� � I �: � . �r��� �� r� ► . ��� ,�• ��. , ,.:.� �� ����, .:�:.►� --� . ����� �f��lG�•� _ � - •- � '3 . � :-��.-� � ? ��;�� ,.,, ��,�,����� ,�� . : � . `. � `� 1 �i` 1��li�;��r�c�•`�'`` �. . �,�\ � � •�� � ���1�����s�► ��: i � � ---' -�` ►Y � � �l � +� r � �;��1�' '��� ' i �� ►� � t�; � + � � . ,, �� r � . - � � , ,-. ���_ � � � � � � � �r � �� �, . � .,�� �., ��� _ �. ' � ���: � ►.�.r.�►� � �:, �`'�'! � _ � `ar. �== . ' � . � �, 1,,; '��i `'�� , � � .� �ti,. . �� �, ♦ . _� � � �,�., ., �,, r���v ��, . . '�� ���. -- • � _ —.�� . :k ����� ' � � � ' � � � I� � i� �. ��� � � I t ,�j�; � . � � , ,� , , , ;�.. i , �, � � ; , , ,, � � �` � � � � � - � �, _ ��� �� � .� - - ,,, . .� �, ���I�i�l - . � � � ' �� �� '; � � ` • , � . r '. � • . � � � . � � � • � � � � �� '�� � / � � • � �C . � ; • • ' � 11 � , � • � / - - . i' / I 1 � � _- --- , � 1 1 1 1 1 V. CONV[:YANC� CAI.CULATION The calculated 100 year peak 11ow from this site is 0.42 cfs. See the hydrograph calculation in section IV of this report. On the following pages of this report section is a pipe flow caiculation indicating that an 6" pipe will carry 0.92 CFS when flowing at 93% full, maximum capacity. �l he rational method was used to check the proposed pipes for the 25 year and 100 year frequency storms. `I'he proposed pipes wcre found to adequate to handle the calculated riinof�: Yg. — 14 � �•. 170'-6" � I� S=2X . \` ,``' '• `. I ��� ---- ` _ . � T � ., � �2 � � �� ► 28� �2" ' � I --- ' S=0.5% .� i ; --�_..,. 1 b� / � •��_. A2=l�.54AC. i __ �� i � - � ' � � ---, /�jr;, I f I � � ,,, �t�s I � 3�—B� ' i ' �� . � � � � �� I � 'S=9•`� ' ; � ' i ' � l ' ° ' �,a. �� � , � ; ; � � � � � , � , � , , , , , , ' .___"""____"'� ' l"_"'�__"'_'__'__l .___"_/ I L"_'_"' �LdM� �_'____-__-_ . "__'._____'J r� � l � I ---- ------- ----- ------ ---- -------- ----- -- 33-8 I ---�- ....... _._.. _... _ • - --- S=2% I � i w — - _ s�.m--------� –—�---� , _..•_----- -- — I --�- — ar ss a.m + I � ._'i. ~ __ _ _ ` �� --�-— � --e--_ � I # I � i � � A1=0.13AC. � 1 , � � ROUSSO SHORT PLAT + � . _ . ---- --- ---- - ----�� CON 1/EYANCE CAL CULA TION SHEET � 5/ 8/03 Engenious Systems , Inc pag� 1 . ROUSSO SHORT PLAT CONVEYANCE CALCULATIONS —--------------------------------------------------------------------- - --------------------------------------------------------------------- REACH SUMMARY Routing based on Seattle family @ 25 yr freq Network LINE1 : Pipe Reach Basin Area --c- --��h- --5um- --3��- --i-- --QAct Dia -Mann -Slope -QE'ull �'fu ll -Vact -Length --it-- ---------- Id ac --czA- - nin inJ6r cfs in --a-- ftJft cEs fps fps ft nir ------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------ P1 �l 0,13 0.90 0,12 0.12 6,30 2,T0 0.32 8 0,012 0.0900 3.94 11.28 6,76 33.00 O.G8 P1A 0.12 0.38 2.68 0.31 8 0.012 0.0200 1.86 5,32 3.96 33.u0 C,14 Network LINE2 : Pipe Reach Basin Area --c- --c�A- --Sun- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Yfull -Vact -Length --tt-- ---------- Id ac --c�A- - nin iaJhr cfs in --n-- ft�ft cfs fps fps ft nin ------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------ P2 A2 0.54 0.68 0.37 0.37 6.30 2.70 1.00 12 0,012 0.0050 2.74 3.48 3.21 2B4O0 0.15 • 5/ 8/03 Engenious Systems , Inc page 1 ROUSSO SHORT PLAT CONVEYANCE CALCULATIONS REACH SUMMARY Routing based on Seattle family @ 100 yr freq Network LINE1 : Pipe Reach Basin Area --c- --c�A- --Sue- ---Tc- --i-- --QAct Dia -Nann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c�A- - �in in/hr cfs in --n-- ft�ft cfs fps fps ft oin ------------------ ----- P1 A1 0.13 0.90 0.12 0.12 6,30 3.40 0.40 8 0.012 0.0940 3.9� 11.28 1,23 33.00 0.08 P1A 0.12 6,38 3.38 0.40 B 0.412 0.020D 1.86 5.32 4,23 33.00 U.13 Network LINE2 : , Pipe fleach Basin Area --c- --c�A- --Sun- ---Tc- --i-- --QAct Dia -�ann -Slope -QFull Vfull -Vact -Lengtb --tt-- ---------- Id ac --ctA- - �in in/hr cfs in --n-- ft/ft cfs fps fps ft �in ----------------------- P2 A2 0.54 0.68 0.31 0,31 6.30 3.40 1.25 12 0.012 0.0050 2.74 3.48 3,41 28.00 0.14 � -- ��j f q , J I �lr�ulai �tia�i�ie1 Hnalysis Solved with Manning' s Eq ;.. .. ��+1-. . .. 1 iT„ , F,�..-�.. Comment : 6" TIGHTLIN Solve For Actual Dis�;���� �` Given Input Data: Diameter. . . . . . . . . . 0 . 50 ft Slope. . . . . . . . . . . . . 0.0200 ft/ft Manning ' s n. . . . . . . 0 . 012 ' Depth. . . . . . . . . . . . . 0 .45 ft Computed Results : ���p {-! ;r,( � D�/ 2 GfS Discharge. . . . . . . . . 0 . 92 cfs Velocity. . . . . . . . . . 4. 92 fps Flow Area. . . . . . . . . 0. 19 sf Critical Depth. . . . 0 . 46 ft Critical Slope. . . . 0 . 0197 ft/ft Percent Full . . . . . . 90 . 00 � Full Capacity. . . . . 0 . 86 cfs QMAX @. 94D. . . . . . . . 0 . 92 cfs Froude Number . . . . . 1 . 10 ( flow is Supercritical) �(�� - �� �;' �a rc i�F_ r-��� �-� `/Dr�v �2 x�r��/ — �. �/Z G �S i—�� 7 t-�C__ � ►7-� � ,� Ti���� � ��iE c� �c F"vr� �� JD F' f� /�� 13 /_ l7Ll N .a/� J i0/�! �2157 iN Open Channel Flow Module, Version 3 . 4 (c) 1991 Haestad Methods , Inc. * 37 Brookside Rd * Waterbury, Ct 06708 r� . --- �� VI. SPECIAL REPORTS AND STUDIES A geotechnical report was prepared by Icicle Creek Engineers, and reviewed by the City of Renton stat��for the Yreliminary Short Plat. I I'�. I�� � SIN AND OTHER CbMMUNITY ARFAS ��' V11. 13A I None I P�. - 20 VII1. OT��t� �ERMITS Residential Building Yermits � Pg. — 21 IX. EROSION/SEnIMFN"1'A"flON ('ONTROL 1)F.SICN The temporary erosion plan will t�e d�si�;ncd to rec�uce the chances ihai any cc�nstruction rc;latcd silty runoff will leave the site and affect downstream facilities. We will assume that the temporary sediment trap will be constructeci toward the northwest corner of the site. This will be the lowest corner to install a tempor��ry sc�iimcnt trap that ���ill b� ahle tc� ca�ture ��nv run��fl��rneratecl ciurinz road or house construction. From pages 5.4.5.1-1 of ihc 19�I(1 KCSW[)M a sediment trap f�r less than 3 acres cievcic�E�n��n� should contain a pond whose minimum surface area is calculated using the 2 year peak runotl "The trap should have at least a 3.5' depth to allow settling of the silt particles. The minimun� surface area is to based on the t��rmul.�: SA = FS (Q2/VS i FS = Safety Fact��, Q2 = Peak 2-year developea tlow = 0.17 cfs V2 = Particle settling velocity = 0.00096 f/s SA = (2) (0.17) / (0.00096) = 354.2 SF. Required 3:1 side slopes U.0' - 2' x 5' 1.0' - 8' xll' 2.0' - 14' x 17' 3.0' — 20' x 23' 3.5' — 23' x 26' SF at 3.5' deep 598 SF—OK 4.5' —29 x 32' 1' freeboard The sediment trap should be constructed at the lower portions of the site ���. _ �� J TX. BOND QUAN`�'�'��S I I I I � �I Pg. - 23 , � ✓ X. MAW"fI�:NANC[? AND OP}:RA"f'IC)NS Pg. -24