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HomeMy WebLinkAbout02857 - Technical Information Report TECHNICAL INFORMATION REPORT U n ion Park Short Plat June 16, 1999 Prepared For: John E. Petersen Jr. 748 Vashon Place NE Renton, WA 98059 (425) 226-6169 Prepared By: t;n�ineerin� e Plannir�� Surveyiri� Penhalle�on Associa tes Consul ting Engineers, Inc. 7�0 SIX'"H �TREET K:RKLA\D. WA 98033 (425) B27-2014 S_ CIS,� ' 1,�� o As O� A� � � � �'o� ����o,�4� �w�� ', 13T8 ti G"�6�9�s6lONAL E�G ! rEXP1RE3 3 0 0 2857 TABLE OF CONTENTS Page I. Project Overview .................................................................................................. 1 VicinityMap.......................................................................................................... 2 II. Conditions and Requirements Summary (N/A).................................................... 3 III. Offsite Analysis.....................................................................................................4 IV. Detention/VVater Quality Analysis and Design...................................................... 5 V. Conveyance System Analysis and Design ........................................................... 6 CBAreas Map...................................................................................................... 7 Area Table and Composite C Value ..................................................................... 8 ConveyanceTable................................................................................................ 9 VI. Special Reports and Studies (N/A)..................................................................... 10 VII. Basin and Community Plan Areas (N/A)............................................................. 11 VII I. Other Permits (NlA)............................................................................................ 12 IX. Erosion/Sedimentation Control Design............................................................... 13 X. Bond Quantities Worksheet (N/A)....................................................................... 14 XI. Maintenance and Operations Manual................................................................. 15 Project Applicant: John E. Petersen Jr. 748 Vashon Place NE Renton, WA 98059 (425) 226-6169 Project Engineer: David Cisakowski, PE Penhallegon Associates Consulting Engineers 750 6�' Street South Kirkland, WA 98033 (425) 827-2014 98516.00-Union Park Short Plat 06/17/99 I. PROJECT OVERVIEW General Description This site is located in the NW Y. of the NW '/4 of the NW Y., and the SW '/ of Section 10, Township 23N, Range 5E, Willamette Meridian, in King County Washington. The site lies on the south side on NE 8�' Street between Union Avenue NE and Vashon Place NE in Renton. Bordering properties include a school to the north and various residential properties to the west, south, and east. � The proposed Union Park development is a 6-lot, 1.00 acre short plat. The site is currently the site of a single family residence (4103 NE 8�' Street). Proposed site improvements include 5 new single family residences with associated grading and wet utilities. Additional work includes: 1) frontage improvements on NE 8�' Street (located along the north property line of the site), 2) regrading work over the adjacent property (located to the west along the north portion of the west property line), and 3) private road improvements over two adjacent properties (located to the east along the north portion of the east property line). The site property, the south side of NE 8`h Street, and the private road improvements have been included in the calculation for storm water pipe sizing. Storm water detention and water quality for this site have not been performed due to mitigating circumstances. , Site Drainage Features Topography of the site is relatively mild with the exception of a small embankment located over the northwest corner of the site which has a slope of about 3:1 (horzontal:vertical). A site visit was conducted on March 2, 1999. At the time of the visit it was not raining and the site showed no areas of erosion, however, some ponding was evident immediately adjacent the south of NE 8�' Street. Future development will eliminate these areas of ponding with a minimal amount of grading. Site vegetation consists of mainly grass and low brush with a number of both deciduous and coniferous trees dotting the site. The existing house is located near the middle of the site. According to the Sensitive Areas Map Folio, King County WA, December 1990, the subject site is not located: • in a wetland area • along a designated stream or within the 100 year floodplain • within a erosion hazard area • within a landslide hazard area • within a seismic hazard area • in a coal mine hazard area. 1 98516.00—Union Park Short Plat 06/17/99 The soil is primarily Alderwood sandy gravelly loam, hydrological soil group C. Existing storm water travel on site consists of sheet flow across the grass and low brush areas towards the no�th, south, and east sides of the site. No channels or evidence of concentrated flow paths could be discemed during the site visit. 405 RENTON �� �� �2tn �`� PqRK I z p NE 8th St. � I � PROJECT w Z LOCATION O 4th � ��a Vicinity Map 2 98516.00—Union Park Short Plat 06/17/99 II. CONDITIONS AND REQUIREMENTS SUMMARY Not appiicable to this project. � I 98516.00—Union Park Short Plat 06/17/99 I Iil. OFFSITE ANALYSIS Upstream flow is minimal, if any, since this site is located over elevations slightly higher than the surrounding area. However, with the frontage improvements proposed for NE 8�' Street, offsite flow from the south side of NE 8th Street between Union Avenue and the site will contribute to the site storm drain system. During inspection no signs of sloughing or erosion problems were noticed. Proposed downstream flow begins at the southeast corner of our site where an existing 12" CPEP is located in an existing utility easement. This pipe is part of the Vashon Place development constructed in 1997. The following table shows the drainage from this point and down until it discharges into the Orchards development. LENGTH DIRECTION SIZE/TYPE COMMENTS 71 LF East 12"CPEP Under roadway/landscaping (Vashon Place) 76 LF East 12"CPEP Under roadway(Vashon Place) 30 LF East 12"CPEP Under roadway(Vashon Place) 67 LF South 12"CPEP Under roadway/landscaping (Vashon Place) 108 LF South 12"CPEP Under landscaping (Orchards Development) Approx. 100 LF North Swale To Orchards Development West Detention pond The swale listed above is part of the west biofiltration swale for the Orchards development. The swale empties to the west detention pond (Tract 100) of the Orchards development. The outfall from the west detention pond is at the south end of Tract 100. The detention pond drains to a large wooded wetland befinreen Tract 100 and NE 6th Street. It is assumed this wetland is Wetland W-20 of the City of Renton Critical Areas Inventory of June, 1991. Considering the small size of the Union Park development there should be no significant impact on this wetland. � 98516.00—Union Park Short Plat 06�'17i99 DETENTIONNVATER QUALITY ANALYSIS AND DESIGN The west detention pond of the Orchards development will provide stormwater detention for the Union Park development. A previous study of the west detention pond prepared for the Vashon Place development indicated that the level in the west detention pond rose only 0.02 feet (during the 100-yr. Storm event) as a result of increased flow from the Vashon Place development and the detention requirement was waived by City of Renton. Since the Union Park development is one-half the size of the Vashon Place development its impact will be considerably less than that of the previous development. Therefore, the applicant is requesting a detention requirement waiver for the Union Park development. As part of the construction of the Vashon Place development, the existing west biofiltration swale of the Orchards development was widened to handle the increased flows from the new development. The existing swale is designed to handle 1.20 cfs (2-yr. storm event). The Union Park development will add only about another 0.20 cfs flow to the existing swale. Additionally, current water quality standards (Stormwafer Management Manua!for the Puget Sound Bas, Ecology 1992 and King County Washington Surface Water Design Manual, Depa�tment of Development Services 1998) use the 6-month storm as the wa�.. quality design storm. The 6-month storm precipitation is only 64°/a of the 2-yr. storm precipitation, therefore, the applicant is requesting a water quality waiver for the Union Park development. 5 98516.00—L"nion Park Short Plat 06/17/99 IV. CONVEYANCE SYSTEM ANALYSIS AND DESIGN The conveyance system wiil consist of a series of area drains, and Type I and Type 11 catch basins. The pipe used will be polyvinyl chloride (6" diameter) and corrugated polyethylene pipe (12" diameter). Minimum slope on 6" pipe will be 2.0% and 12" pipe will have a minimum slope of 0.5%. The following tables and calculations were used to size the conveyance system. i 6 98516.00—Union Park Short Plat 06/17/99 � ■ ■ ■ ■ ■ ■ , � i � ■ ■ ■ ■ ■ ■ - 1'=40' � ■ � ■ ■ � ' 30' ' � �, ' ■ . : � _ . - �� � � _ . � ■ Nd�iH no urraN �ve . . _- .--- -s� ■ - . � f��i/ � ` ��s�su��a�[a�ir�ss�a��d�� tt�et�taut���a�� saasa�saas�s�s asasrss��sr��s ---- � , . : ... .; ■ , . , , .,: ■ �- — — — L- — �'�- -�. . : . �- — --— —� j ■ C . ; I I . -�*�' �- , _ - ; � F I. __ � ' � . ■ --� : � -^f . - F' _ j ■ .�� 1 -_ I RY1 k W VEFtT. � �1 �_— — - — � � . -. .I " I � • I ��►:�,m � o I I : � . ���2� a >--� r .x.`` i �: ; _ , - .�, ; # -� AD#3A r�Nc oa+s,Ruc„oN � � I I � ,.�.�113 AC�2�.S�, ' `� i ' I ■ -�==' � 0.29T ACRES I �. ..a� - N T� t� .w �r � . •� � , I i : .--; �- 8 PVC I .- � I , 1 WY �.1NVQt7 _ � I 6� P��� � . . � ■ . � ' L - - - - - - - � , y � e��im�►nr� � `" . � � � �� � � suRa+c oa+srnucna+ I � — — — - ' � ■ � � *.....■o..� �AD#2A � _ r ' � ; Z 75 LF 6 P�C -<.:. i � 67 LF 6'POC - ■ Q�2 ZPM ! � r - - - r� i � _ - � 10.25� ACRE�S �fs`�2� C # ' : � I - _ . I . , i �� t � I I�n�, � � I I � � i � 0. i ACR S pp cB��- s I,f � + � �F � � I � : � . ELEYAfiIONS TO . . � 0.09�1 ACRES � :I ./ i . � ' - . ' -� CB#2 I ���,,,s'"1EDiRucna+ � � � i �: _ � � �l I �.�0 2�8 ACRES� ��=- 6� P � � � _ � � ■ i ._ . : .__ I � ■ �-''/ . ,g ' . ���----L ��. � � �ry.6• P C8 TYPE-1 I I : � - � � � � ]f RtY 409.58- . -' � � + � I � 29 lF 12"CPEP � - � � �I Mv 4o�.oz- w� � � ■ . + 5�0.00.5 �t � - ... - . � � , INV 406_52-�N . , � � ■ � _ + � I 6- P� + ... . . _� 1iT1 F�_ , ' _ . I ■ ' _ _ � -�.._ I — I � - . . N iA� � � � � � -. -.� l� — — _. :, . ----- -- - --'-- --- -' . , _ . . _ . - __..�'.. I � �.�. � -�5;0.00 � ♦�� --� ■ t _ � l �t. _ - - --- --�'__---��--� --------- --- �- -�n- --- ,�� �_...r ' .. ., M t4720 � ,. ��� . ,._- �� . -- -r- � i "� - � -, _ . -� (MATCH TO EJa57WG GR/�DE) C8 TYPE II - . ._ . � � . _!- . . " . '' IHV 406.10(51� RIN t41Q5 � � -� - " ' CB TWE I -' INV 105.60�N.E� � � (�1AV T�TO E)OSIING GRADE) _ . , . ._ ' NfH N��. � � RIY 409.85 � �CONNECT 70 DQSlINC 12�CPEP . INV 105.74(N,5) 13B LF 1YCPEP - ' -- - IHV 406.65 . � WV t405.5, FlF1D VERIFY EI.EVATION- PPoOR TO STORM DRAINAGE SYSTEM: � 5-0.005 - , aa+srnucnaH zo � i z'caEa - _. _s-o.00s � - -, � �: � � � � . � ''� ~ � . \�l . _ - . . � • i � _+ , i U \ \ \N �;o� before yolu ,��l������ � '������ ��Si �l9' � ��,�� � 1-800-424-5555 ��4.w+� `��`�aa �,b�c�� � a���� i DESxtIED CAIA -.- - � EngineerSng pa^ 1�/u�� PlanninH 06/16/99 ,108 MUUBER �uew CAA1 -- Surveying UNION PARK SHORT PLAT BASIN AREAS 89516.00 °Ep�D �'� Po sxn+1srae�Er SOUTH SOKIRKl.�'+e'D. ,.c�a aUICPIlg51�j]�ij]e�e�, 1� �`� �-_ao' CONVEYANCE CALCULATION �'"'��10 �'''bu�as°rc sw � :.� • -,�� — �r XX x XX Union Park Short Plat Catch Basin Sub-basin Areas and Composite C Value Sub- TofaL Asphalt/Concrete Grass Composite Basin Area Area Area C Value Acres) (Acres), C=0.90 Acres), C=0:.25 CB#1 � °`' � ���0�312 0.225 0.087 � "` 0.72�� I AD#2A �.0:113 0.057 0.057 ' 0.58 � AD#2B 0:254 0.127 0.127 -> 0.58-. - CB#2 0.278 0.139 0.039 0.49 CB#3A j 0.297 0.149 0.149 ' 0.5$ � CB#3 - 0.000 0.000 0.000 ' CB#4 0.091 0.046 0.046 0.58 9516AreaSht.xls 6/17l99 8 1 Union Park Short Plat � CONVEYANCE SYSTEM ANALYSIS AND SIZING TABLE USING THE RATIONAL METHOD Location Sub Area C C*A Sum Tc i R /(R) Q(R Pi e T . Slope Q(F V V L Tt % d/D Basin (ac) C'`A (min.) (c.f.s.) (in.) n (ft.ft.) (pipe (pi e (at (ft. min.) From To Number full) full) Q(R)) AD 2B AD A B 0.113 0.58 0.07 0.07 . .80 2.73 0.18 6 0.01 .0 0 0.86 4.38 3.46 7 .0 0.4 � � ' . AD#2A CB#2 AD#2A 0.254 0.58 0.15 0.21 6.3 0.80 2.73 0.58 6 0.012 0.020 0.86 4.38 4.68 75.0 0.3 • i � ' � CB#3A CB 3 CB#3A 0.297 0.58 0.17 0.17 6.3 0.80 2.73 0.47 6 0.012 0.020 0.86 4.38 4.40 5.0 0.3 � ' . CB#1 CB#2 CB#1 0.312 0.72 0.22 0.22 6.3 0.80 2.73 0.61 12 0.012 0.005 2.74 3.49 2.83 75.0 0.4 � � ' . CB#2 CB#3 CB#2 0.278 0.58 0.16 0.60 6.7 0.77 2.62 1.57 12 0.012 0.005 2.74 3.49 3.58 138.0 0.6 - � ' . CB#3 CB#4 CB#3 0.77 7.4 0.73 2.47 1.90 12 0.012 0.005 2.74 3.49 3.79 29.0 0.1 • � � ' , ' CB#4 EX CB#4 0.091 0.58 0.05 0.82 7.5 0.72 2.44 2.01 12 0.012 0.005 2.74 3.49 3.82 20.0 0.1 � ' . .o Project: Union Park Short Plat R= 25 yr P R)= 3.40 Calcs b : CAM Job No: 99516 Location: Renton, WA Date: 6/17i99 Page 1 of 1 C,�17i90 9S 16('om�ev.XI.S VI. SPECIAL REPORTS AND STUDIES Not applicable to this project. �v 98S 16.00—Union Park Short Plat 06/17/99 VII. BASIN AND COMMUNITY PLAN AREAS Not applicable to this project. �1 98516.00—Union Park Short Plat 06/17r99 VI11. OTHER PERMITS Not applicable to this project. t2. 98516.00—Union Park Short Plat 06/17/99 IX. EROSION/SEDIMENTATION CONTROL DESIGN Due to the topography of the site and its small size, being very flat, minimal erosion and sedimentation control will be needed on this site. Silt fence will be placed along the perimeter of the site. Runoff will be directed to CB #2 and then pumped to an existing catch basin located in the Vashon Place development. Catch basins inserts will placed in CB#2 and the existing catch basin located in the Vashon Place development. A stabilized construction entrance will be constructed at the entrance to the site off NE 8T" Street. No erosion problems are foreseen on this project. 13 98516.00—Union Park Short Plat 06/17/99 X. BOND QUANTITIES WORKSHEET Not applicable to this project. !4- 98516.00—Union Park Short Plat 06l17!99 XI. MAINTENANCE AND OPERATIONS MANUAL See Appendix A of the King County Surface Water Design Manual, 1990. r5 98516.00—Union Park Short Plat 06/l i?99 � - � , �. � _ . _. .�oe (J N/ON 7�hK K 5.P . Penhallegon Associates Consuliing Engineers, Inc. sNeer;No. � oF Engineering • Planning • Surveying CALCULATED 8Y � DATE 6- �^Z�00 750 Sixth S�eet Sout6,Kirkland,WA 98033 CHECKED BY DATE Phone:(42�827-2014•Fax:(42�827-5043 SCALE !i ; ' ; , A ; ! SOIGS !�__ /"r�+ � __�—.- Fi-rDrCcc.Q(eL� . So�L laRDt9P 4� ___;.._� ' , : _ � , �i r �._DO—" . —_ ___ _ ; .- _- � � - --- - -- - -- - . _ __ !- --- __ :..- ; ; •- - - ---- ------- _ ' ` -- - -- -------. __ ,. . , • -� ------ ._ ...-:—;_; �,- ..-1 . : , , -- : TaT�rG___�4�SiF__ _CQNT�l�UT1N(, _.7� ; (WC�t V�tv�LT': ._O�_`I� A�G — ' --- :_ ; ' ' . 0. 5t k� ' + ` ' ---��!i AE�VIOVS ___/E�Ei4: _�__ � _G/�1 =T_g t� , : ; ; ; ' : __ . 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SYMBOLS Symbo 1 1 . : � � i - Aa,Ac,Se Agf� Alderwood gravelly sandy Loam, 0-6$ slopes - Ab Ae A� Alderwood gravelly sandy loam, 6-15$ slooes .- � - ' ��--..�• Ad AgD Alderwood gravelly sandy loam, 15-30€ slooes , . � Rh AkF ?�lderwood and Kitsap soils , very steep Aa,Ac AmB Arents , Alderwood material , 0-G$ slopes Ab,Ae AmC �rents , Alderwood mat�rial , G-15$ slopes Eh ,Ek An Arents , Everett. material Cc ,Cr BeC Beausite gravelly sandy loam, .GiS$ sl�pes Cd ,Ce BeD Beausite gravelly sandy ioam, 15-30� slopes �d ,Rk Bet Beausite gravelly sandy loam , 40-75a slopes Nc,BF Bh Beilingham silt loam Pk Br 5riscot silt loam Bg ,Bh Bu Buckley silt loam Cg Cb Coas�al beacnes , Pd �a Earlmont silt loam Ea Ed Edgewick =ine sanci�� ].oam Ba ,Eh,Se ,Sg �v3 �verett gravelly sandy loam , 0-So slopes Ek ,Ba ,Sh � 3c EvC Everett qravelly sandy loam , 5-lSo slo�es Eg ,Bb ,Bd EvD Everett g�ayelly sandy loam , 15-30a slopes EwC Lverett-Alderwood gravelly sandy loam, 6-15� `-=�'�� Gravel Pit G . P. Gravel Dit �;,.��t''` `-��:-:A�:, . . . . . .. . . . .. .. . _. _ . . ._ . __ .; _ -_ i_:- �_ . ,- . - . _ ,. . . �+1�.1.1 . . . , � � ' KING COUNTY, WASHINGTO �', SURFACE WATER DESIGN MAIVUAL TABLE 3.5.2I3 SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS ' , . ��. . SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in t382) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainf�ll disiribution, 24-hour siorm�duration. . CURVE NUMBEAS BY � . � HYDROLOGIC SOIL GROUP ; LAND USE DESCRiPTION , A B C D Cultivated land(t): . winie�condition 86 91 94 95 Mountain open areas: low growing brush and grasslands �4 82 89 92 Meadow o� pasture: 65 78 85 89 _ Wood or forest land: • undisturbed or ofder second growth 42 64 76 81 � Wood or forest Iand: � young second growth or brush 55 72 8� 86 ' , Orchard: , � with cover crop 81 � 92 � Open spaces, lawns, parks, golf courses, cemeteries, ; landscaping. , good condition: grass cover on 7596 or more of the area 68 80 � 90 fair condition: grass cover on 50% • to 75°�6 of the area 77 85 90 92 Gravel roads and parking lots 76 85 91 Dirt roads and parking lots 72 82 R7 �9 Impervious surfaces, pavement, roofs, etc. 98 98 98 98 — Open water bodies: � lakes, wetlands, ponds, etc. { �00 100 100 t 00 Single Family Residential (2) Dwelling Unit/Gross Acre 96 Impervious (3) 1.0 DU/GA 15 Separate curoe number 1.5 DU/GA : 20 shall be selected 2.0 DU/GA 25 for pervious and I ! 2.5 DU/GA 30 imperviot�s portion ; 3.0 DU/GA 34 of the site or basin 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 i 6.5 DU/GA 54 I 7.0 DU/GA 56 I ,Planned unrt developments, 96 �mpervious I I c�ndominit;ms. apartments, ^^'�s' �� ^^"'^�"^r' Icommerciat business and I ( industrial areas. � I (t) For a more detailed descripti�n of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrolcgy, Chapter 9, Augusi 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. �j 3.5.2-3 , 11/92 aP' ' ' . � � K [ NG COUNTY, WASHINGTON, SURFACE WATER DESIGN MAIYUAL TABLE 3.5.2C "n" AND "k" VALUFS USED IN TIME CALCULATIONS FOR HYDROGRAPHS . - ' + . � 'n,'Sheet Flow Equatbn AAa�ni�g's Values(For the iniial�00 4 of trevel) n�' Smooth wrlaces(concrete.asphall.9ravel.or bare hand packed son �� ' Fallow fields or loose soi wAace(no resldue) j �-� c.univatea soi wdn resaue cove.(s<=o.zo n/h) _ o.os Cultivated soi with residue cover(S>0.20 ft/ft) • Qt7 Short prairie qrass and Iawns • � .'615'': , - Oense grasses a•2� Bemwda grass 0.�1 Range(natural) O.t3 Woods or lorest witlt light underbnish `.0.�0• Woods or torest w4h dense underWush 0.80 •Manning values for sheet fiow only.(rom Overton ard 6leadows 1976(See TR-55. 7986) , 'K Values�lsed in Travel Time/Time d Ca�cenVation Calculations � Shallow Concerrtta[ed Flow (AHer the inilial�00 fL d sheet flow,R .0.1) k, . 1. Fwest with heavy ground litter and meadows(n-0.10) S 2 Brushy ground wilh some trees(n�0.060) 5 3. Fallow o�minimum Wlage cultivatfon(n =O.OaO) 8 4. High grass(n=0.Q15) 9 5. SAon grass,pasture and lawns(n=0.030) 11 6. NeaAy bare ground(n=0.025) 13 s �..,,�, ' 7. Paved and gravel areas(n-O.Ot2) � 27 Channel Flow Qntermitlern)(i.�th6 begirning d visible channds:R�0.2) k� i. forested swale wrth heavy ground liner(n =O.tOF 5 2. Forested d2inage course/ravine wnh defined channel bed!(n=0.050) t0 i 3. Fiodcained watenvay(n=0.095) ` t5 a. Grassed�.ratervray(n=0.090) 17 ` 5. Eanhained watenvay(n-0.025) 2p 6. CMP pipe(n=0.02a) 21. 7. Concrete p�e(Q.012) 42 8. Other watetwaY9 an0 P�Pes OSOB/n Channel Flow(Continuous�ream,R -O.a) k� 9. Meandering sUeam with some pods(n =0.040) 2Q �0. Rock-nned sUea�n(n-O.D.�.sl 23 t 1. Grassak�ed sVeam(n-0.030) 27 12 Other streartu,man�nade channels and pipe -0.8�' ,`-� •'See Chapter S,Table 5.3.6C for additional Mannings'n'va��;es tor open channels 3.5.2-7 1� • • � . . . . � . � . ��wr�,,��A�� r'i� � ' . . i�. � , �tv.����.�,� �� � t=,- �� `< � ��� ,. :. _�' ��1, Ir� . . �i ���� � � � \ � � ��� � � � �� � �,��i � � . �` �� S � � �� '��, ' I�'� � iG'�i�� ��. . �!� � � � � � �� � � � , d , , `����. +: �.". `,, .. . � _�.;-•w � E/�" :,� �. ,��Ai ��— 'w ��i"r'7���1��� ,�r,�E�'�' �!�► .a.�..;� i� a '���p ��'�r� `- _� 'I�►� �-� �f i� � �� � -� , �� �•.� P . -� • `�� � ��`��= �=-��� � �.� ���. `' ��o�.�'Z ���.���� ,�% ;�A�� �, � � .z.= � 1� �/ -�'!�%��,,.�`' -��:���� � �;, �,..�. �� ��`,�'� % �, �.- ' � l���� �1i���•\ �� ������ tW� r � '' ��`� � -��_ -��7w����-�����'... � � ����� � � r ,� . -�\ _ l;�� .� ��-� �� ;�� � .�� � '����E, f 1AI1�,4,. -� , � ��� � ~�\ ' ei � '' ' �, ' ' �1 1� ,,�!��►�� \ — �• �� ��, r � �� .�;, � �� �-.. � �: � , ,�� _ , �, = m �. _, �,� ��; _ �,� ��� ., �a�"'"�I��E �� �_ �►,��- J � � --�����j��� �•. � �� � _ ` _��`�\I '��.� �,`p� �"�.. �I���l�''�� . �� i� 1� � �� � ���I .�,,�- _ � , �� 1 � � i� � ��G �an � �.�w��' . .�3�� ,{, �,�� �i -� . � , , � , �� . , i S J � o A�!�� . ��. � , �.�;'_'��� � �- �. l� �. _ ��� ��n I� ���� ' � J�� ' �1� �, ������ ,,. � � A � �z �� - ....� �ww��� �T�;«w� ._-�- ► , � 1 _ �� r . � � . i ' — � �i � � ! � �� 1� • •,. �� 1� , . �t�I�l�t'��1�� _� . . . . - . - . . . , ��'���1 �� .. . . R ��►�� _ ' ' � 1� . �=� •�e . --_--- - o��,i .,� �� �,. . .� WQ PROP ToC TIlv1E OF CONCENTRATIONS FOR: LJrtION SHORT FLAT (THE FOLLOWING SHEETS USE TI�BELOW EQUATIONS TO CALCUI.ATE Tc) Sheet Flow: T�= 0.42(n5L)0�8 �,2)os�so�o.a Where: Tt: travel time(min). � ns: sheet flow Manning's Effective roughness coefficient(from Table 3.5.2C). L: low length(ft). P2: 2-year, 24-hour rainfall (in), (see Figure 3.5.1 C). - sa: slope of hydraulic grade line (land slope, ftlft). Shallow T�= L Concentrated Flow: 60kS(so)o.s where: T�: travel time (min). L: 1ow length(ft). ks: time of concentration velocity factor(ftls), (see Table 3.5.2C). so: slope of hydraulic grade line (land slope, i�lft). Channel Flow: Tt= L 60�(so)os . where: T�: travel time(min). � , L: flow length(ft). k�: time of concentration velocity factor(ft/s}, (see Table 3.5.2C). sa: slope of hydraulic grade line (land slope, ft/ft). . Page 1 " � WQ PROP ToC TIlVIE OF CONCENTRATION FOR: LTNION SHORT PLAT PROPOSED CONDITIONS-WATER QUALITY CALCULATIONS: Sheet Flow: Segment#= 1 Tt= 7.fi89326 min. ns= 0.15 L= 102 change El. = 7 P2= 2 so= 0.0686 Segment#= 2 Tt= 0.363031 min. ns= 0.011 L= 16 change El. = 0.3 P2= 2 so= 0.0188 Shallow Segment#= 3 Tt= 0.228739 min. Concentrated Flow: L= 65 change El.= 2 ks = 27 so= 0.0308 Channel Flow: Segment#= 4 TL= 0.132745 min. L= 45 change El. = 0.32 k�= 67 sa= 0.0071 T� = 8.4 min. � Page 2 _ I� ******************** S.C.S.TYPE-lA DISTRIBUTION ******************** ********* 2-YEAR 24-HOUR STORM **** .67" TOTAL PRECIP. ********* ENTER: A(PER�, CN(PER�,A(Il1�IPER�, CN(IlVIPER�,TC FOR BASIN NO. 1 0.41,86,0.51,98,8.4 DATA PRINT-OUT: AREA(ACRES) PERVIOUS IlviPERVIOUS TC(��IINUTES) A CN A CN .9 .4 86.0 .5 98.0 8.4 PEAK-Q(CFS) T-PEAK(HR�) VOL(CU-F'1� . .U6 7.83 968 ENTER [d:][path]filename[.ext] FOR STORAGE OF COMPUTED HYDROGRAPH: WQVOL I