Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
SWP272288
July 24 , 1996 TECHNICAL INFORMATION REPORT PROPOSED O'CONNOR PLAT S 34th ST between WELLS AVE S & CEDAR AVE S CITY OF RENTON PREPARED FOR: Tom O' Connor Lang Construction Assoc . P.O. Box 23998t�� Federal Way, Wa . 98093 ok � Tel : (206) 718-8923 PREPARED BY: James Jaeger, P . E . �g1. Jq� 7 Z ��hher P 4ry 20734 �tio��- �41VAL ' EXPIRES 3AI < ` I . PROJECT DESCRIPTION The proposed plat is located in the City of Renton near the southeast City limits . It is situated west of SR 515, southeast of the Plat of Winsper and north of SE 172 St . (projected) . It is within Sect . 29 , Township 23 N. , Range 5 E . , W.M. The development includes four existing large parcels, two with residences and two vacant . The total acreage is 10 . 21 acres for all four parcels . The subdivision will create 41 single-family residential lots . The existing two houses will remain and both will have oversized lots . Of the 45 remaining lots, four will have duplex residential units . The zoning for the three northern lots is R-8 , while the zoning for the southern-most parcel is R-10 . The existing property is a combination of second growth forest, livestock grazed pasture and residential landscaped yard'. The pasture area is mostly 'cleared while the wooded areas have been disturbed by past grazing or other activity. The topography is a constant 15% slope dropping from the east . to the west . l�ae sting access points onto the property arc Ave . SE, via SE 172nd St . and directly from SR 515 . A proposed future access point will also be constructed from S Wells St . within the Winsper neighborhood. •1' I 1, Sk004 SI VW Y-/ 1 L..� 1 f Q _' -*� O11 51 uSN )fll N �� zz eniQ1< 3 'W ^ !•.IRK rd `��RID£ I'Nttt WON V111AGE ARWI05�, + cn CENTER PARK SNl ►1 11t__SI M S Rt IrOfl V1ltAGE PL Sr Siirlhsl J, - - > 12n1 NU1 INN Y .tr•51 O SW 16111 _ - - -�- -- eoo l 6TI l ST 4 o 11 ' /: � s��r1i s1uj .� S — ------. N— as-- G --19 1offG T 1 r Uhl G I 1 t(►lR oc S 10111 �n ST 1 0 ►aeor oc 1 a a. ^ SW 19111 ST 1 xret J, g ST o• $ Y -eml I S 19111 ST _ by n r, I li_1��3 G s TALBOf p k l 1 -q y 2uln Qo`� f11t s' $ �^ Mott 1`0 ARK �1� 00 PUGET d 4 ?'rou i t "r1;1 g cl �1 �"sAY' ZA2I U N SW Z31(1) ST S 23110 Sl NIO 1 �; PAU 1 Q Q S p SW Mill - �_--_ - W 10900 ---- --- •1`..' ��,�^ sl_ S c S 27TIi zS-l--1 S 1 S /nl vl turn Vl ��J' r 7b�i-CI c 5 2u11( - 1 v1 r 1 v o 1 "rl sy •� <., •ly�d 1. � � m.�6. 2501 �I =t E 1Ghr11'v, �.�• 1 W 291H Sl ) 70 r�'Q�.�q�•� f`' S,o� rl rV it., ST I30 3 �l�i Y� f0111 1.1 1 v;$ 3 a 1's }, 1 30111 �y \ - 1 1 1 ST" V31STJ ST `3sil I 'Q ,29 1 --- - -- —$Tr 331t0 Sr 1 S/ t?32ND 0. "' � � In ^_-sE_IujIll ,z SE �I)OTII ;I I ll l r aA 1•- 1 _SW �t�/�Z�t 3.1111 sl S •SE 10 51 I0500 LWsU DI lll SI _I S 51 S 1 3)rll SI - y I)<ill5r rs L � 1 a SW 3S I11 ;ST N Z�ti —' sl s SE 1/61 SW z 41 ST ST 4 Q ,amolit CO rtnSOn 1 Page 1 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET. PROJECTPART I OWNER AND PART 2 PROJECT • • PROJECT • Project Owner T'oyyr y�Vl y— _ Project Name i4N� OrP1 0. Address -P.0 U-h Location Phone 7?1'b - 2-3 -cam Township 23 W Project Engineer �Q,1-,Ac s �1I�eG Qx Range S F= Section 2-9Company So�2 _��2 v� Project Size 10 . 7-1 . AC Address Phone Upstream Drainage Basin Size Q ,S AC Sd.- 3 PART 3 TYPE OF "APPLICATION PART 4 OTHER Subdivision 0 DOF/G HPA F-1 Shoreline Management F-1 Short Subdivision 0 COE 404 0 Rockery [] Grading 0 DOE Dam Safety 0 Structural Vaults 0 Commercial FEMA Floodplain EJ Other 0 Other COE Wetlands F-] HPA COMMUNITYPART 5 SITE AND DRAINAGE Community t C�r� o F - I RL l3m iLL- Drainage Basin PART 6 SITE CHARACTERISTICS Q River _ ( ] Floodplain [_1 Stream :F,-n,<Wetlands k7`T ss 3 — y r rQ G�,,� �o` ecl 0 Critical Stream Reach 0 Seeps/Springs L] Depressions/Swales High Groundwater Table ^ 0 Lake - F-1 Groundwater Recharge Steep Slopes Other Lakeside/Erosion Hazard SOILSPART 7 Oil Type Slopes Erosio Poten'al Erosive Velocities _P0 1�ok- I S°/n F Ps -N 0 Additional Sheets Attatched 1/90 t. Page 2 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET DEVELOPMENTPART 8 • REFERENCE LIMITATION/SITE CONSTRAINT U Ch.4Downstream_Analysis n IT---^ (I a - F-1 Additional Sheets Attatched PART 9 ESC REQUIREMENTS MINIMUM E§C REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION Sedimentation Facilities Stabilize Exposed Surface Stabilized Construction Entrance Remove and Restore Temporary ESC Facilities Perimeter Runoff Control Clean and Remove All Silt and Debris - U Clearing and Grading Restrictions Ensure Operation of Permanent Facilities Cover Practices 0 Flag Limits of NGPES Construction Sequence Other (_] Other PART 10 SURFACE WATER SYSTEM Grass Lined Channel U Tank 0 Infiltration Method of Analysis Pipe System [::] Vault Depression S-BU H Open Channel 0 Energy Dissapator Flow Dispersal Compensation/Mitigation Dry Pond E�l Wetland Waiver of Eliminated Site Storage F J Wet Pond E::] Stream Regional Detention - Brief DescriptionC: of System Operation ��� crr� t��b Z ,?-11 J.9d e-- �J V,n LL Facility Related Site Limitations 0 Additional Sheets Attatched Reference Facility Limitation PART 11 STRUCTURAL ANALYSIS PART 12 EASEMENTSfTRACTS (May require special structural review) - F--1 Drainage Easement [] Cast in Place Vault Other Access Easement Retaining Wall 0 Native Growth Protection Easement L] Rockery>4'High F-1 Tract 0 Structural on Steep Slope Other PART 14 SIGNATURE OF - • • I or a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attatchments. To the best of my knowledge the information provided .�_\• �i Q. �\ here is accurate. sv 1/90 II . CORE REQUIREMENTS AND WORKSHEET The drainage core requirements are identified in the City adaptation of the King County Drainage Manual . Each of these 5 core requirements have been reviewed and addressed in this report and accompanying drainage design. The core requirements were addressed as follows : 1 . The natural drainage discharge location of the site is along the western property line . There are several wetland areas and low spots along this property line but the ultimate runoff is collected by the ditch along the east side of Talbot Road. The developed drainage will collect the runoff into a detention vault and convey the discharge via a pipe to Talbot Road through downstream properties . Additionally, a short dispersal trench will be placed at the southwest corner to disperse the upstream, offsite runoff at its natural location, which is this corner of the property. u 2 . An off-site drainage analysis is included in this report in section VI . A level one off-site drainage analysis is included. 3 . Peak rate runoff control will be accomplished using a concrete detention vault . The discussion and calculations for designing this pond are detailed in section V of this report . 4 . A conveyance system has been designed and submitted with these engineering plans . A network of catch basins and pipes are mostly located along the sides of the roads . The conveyance system will be able to handle the 25 year flows within the pipes and the 100 year flows within the catch basins or road prism. 5 . An erosion and sedimentation control plan has been submitted with the engineering plans . None of the Special requirements apply to this project . The project will produce over an acre of impervious surface subject to vehicular traffic, however the downstream wetland areas are class 2 or lower grade . III . EXISTING DRAINAGE CONDITIONS The existing drainage is basically a combination of sheet flow and shallow channel flow down an continuous 14% hillside and onto a flatter area that, as a result, displays numerous wetland areas . The existing drainage analysis for the project considered the entire project area, which is 10 . 21 acres . This includes the future lots for the existing houses that will not be disturbed. The analysis also considered the existing structures situated throughout the site . The existing ground cover is approx. half pasture and half wooded. Except for a small ditch along the south property line, there are no existing onsite drainage improvements . This ditch primarily was formed from upstream, offsite runoff from SR 515 to the east . There are several small wetland areas along the west property line . This is the low side—of, the site and the natural discharge point for all of the site drainage . There are additional wetland areas further west on the adjacent parcel . These wetland areas are the direct recipients of the site runoff . ' The existing quality of the onsite runoff is tainted by the two grazing pastures . The llama pasture is heavily populated and.. thus generates wastes that are carried by the gheet flow runoff . The llama pasture ends at the west property line so there is no buffer to the wetland areas . The existing drainage analysis was performed using the SBUH hydrograph method and the "Waterworks" hydrology software . The methods outlined in the King County Surface Water Manual were used as guidelines . Following this page is the data sheets used for computer input data . The computer summary sheets for "peak flows and time of concentration are also attached. Below is a brief summary of the existing condition drainage characteristics : Time of concentration: 26 . 26 minutes 2 year peak flow: 1 . 04 CFS 10 year peak flow: 2 . 43 CFS 100 year peak flow: 4 . 21 CFS pervious area : 9 . 90 acres CN=82 . 9 (weighted) impervious area : 0 . 31 acres, CN=98 F'Rw���LiJF�E� DR� ►�► P�� �f�RL� �IS r r� (0. -I Olt rpm C �0f-t3, ' ram z , c�3F2v�. f\1v tiY�CFI�'. `�• C �1�0 ��w�� jo,I�"� I u e_wo - Loft Iwo I Zco c - Z000 S . 3,(OCR s , 9 c> aLU..)ln c r-4 � s C� 5. 4 Ef� lips( e� w 3 Tl37, r nC OF COtac.�.�T'RTI ca i �. ��C_c�►,��02 ARIA ►NA�� C�R1�111�I��E c'�l_c�S 6� 35u� ��C1a 'I(7� !) C�-1`n •r.',l � � 1\1'>�...o ) C�UQ-►� U..)C�•S 350 TG - 4-, b2 I ( �� Cyr r,f�t,�F�� ��Yf�•{11�Y.,'� i I 4, TSc7�•-UV��t_5 - i Pic) 2 t 5, F%F Ntr— FLoU_)S 2 .43 �Fs CJI�a 10/18/95 Jaeger Engineering page 1 O' connor Preliminary Plat Drainage Calculations Predeveloped hydrograph summaries BASIN SUMMARY BASIN ID: A10 NAME : Predeveloped, 10 year, 24 hr. SBUH METHODOLOGY TOTAL AREA. . . . . . . : 10 . 21 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 9 . 90 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 90 TIME OF CONC. . . . . : 26 .�26 min IMPERVIOUS AREA u ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 31 Acres CN. . . . . 98 . 00 ' TcRea,ch - Sheet L: 300 . 00 ns : 0 . 2400 p2yr: 2 . 00 s : 0 . 1170 TcReach - Shallow L: 350 . 00 ks : 3 . 00 s : 0 . 1630 PEAK RATE :, 2 . 43 cfs VOL: 1 . 19 Ac-ft TIME : 480 min BASIN ID: A100 NAME : Predeveloped, 100 year, 24 hr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 10 . 21 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 9 . 90 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 90 TIME OF CONC. . . . . : 26 . 26 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 31 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 300 . 00 ns : 0 . 2400 p2yr: 2 . 00 s : 0 . 1170 TcReach - Shallow L: 350 . 00 ks : 3 . 00 s : 0 . 1630 PEAK RATE : 4 . 21 cfs VOL: 1 . 90 Ac-ft TIME : 480 min BASIN ID: A2 NAME: Predeveloped, 2 year,, 24 hour SBUH METHODOLOGY TOTAL AREA. . . . . . . : 10 . 21 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 9 . 90 Acres TIME INTERVAL. . . . . 10 . 00 min CN. . . . : 82 . 90 TIME' OF CONC. . . . . . 26 . 26 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 31 Acres CN. . . . : 98 . 00 TCRea,ch - Sheet L: 300 . 00 ns : 0 . 2400. p2yr: 2 . 00 s : 0 . 1170 TcReach - Shallow L: 350 . 00 ks : 3 . 00 s : 0 . 1630 PEAK RATE : 1 . 04 cfs VOL: 0 . 62 Ac-ft TIME : 480 min I I \ � _ 'tYl Asir' r4 �' •,, p •yl ` - _- - _ p ZI s p I�1 I, , I r t. L •1,. 'Ij .•11, - ,Q£t rQ� ,., Ii�- - -a�_ � If-�-'1 �Ci" rAk 1 � ; '1 1 ,�'D'\'„',''1�,;,!• 1, Ndl. ' r 1 1 � 1 - - �-�-_- � �, • 4Y 1-r 11;•= � ,r ,' rI ,I , 1. i 1. ' �.� �»..n�.r r.� tl!� ,s sl,.r.•.... les.r,r t I 1 1 I ; � l ! i I 1 .. I•.r M,.I �r{. �� I11� , 1"' lli ! , fI 1 pppl , / / � , ;' �7 i', II, �11�'' O Ftf I t 1 f' j.I l .. , ;I.� , , 1 671.1 I j �I ' ' ��} -✓r-•f r/ -r r ,1/t i `j � 1 ,1 1,. .1 i ', \` 1 14, ,1 �t1- 1 1 1 '.L::. ' r Ig$3 _�� 3 tf.o►.vo'. /�1 e' o Iz 3 :[L�y:Bp I ry y \ 1 �;a '+�.. 1,`0! ;I� ,•Ii r ''1' L.' I I Y ' r' I tl ',t ; i I 1 tf'I'•, O '1 ,o \`, �,�{ , `, I , 1 t ,1 , l t \•;e W ID .. � I IITY e G-, FI('T \G �y \ F9h 71. vt , �'•' 1 t 1 ' '{ I 1 3 1 , �Rn,°. FACG'\''�``rur. \ '\ ,.I 1$'1 1� ; 1 � t, � � I I I ! 1 I o n lei ' " r �, - M PF T�TI[y a u 1 B i� yP �c( 71�� 1 ���� ��G .•C �r Iy � ,� � � �1� t ;•,1 I '., ; 1 �,I�It � �' �3� � ' � ;�,. } to '��•� Ij � k � � � l 1' � , ��I`sl ,T 1�-��I, � 1 t � I t, , tI'1 , - i ! ! _ a '1 O "�:•184111� ���� ' ��, �� � � �� 'I t I -� r--- ����` II III ,, ! I\ , — - --- - �,-gib. --1 r .,�.�,_��, / ► .B .i1J•, , ) ;`� 1' � 1 � _•, ryF�'m , 'i �,� f i •/I•P � i 1 II('I �I � 5 .l $ Im I •� � I ' ' I I ' c i961K Y ' 1 Al �� '1 1' I 1 1 ' 1 7 , j■T r I\ ` '\ \ ` , ', �,1 I v,•_, rr • R ►9z a P o. p ('(� t ,� _ � i i' i I I I � , qq m py u I - , �, I '• , �. I, T\1 r�•\ � � t��egs Ja I ,v ;■� ; \� Irb�; '` I i t�R �; 8 1 , �.�. ` ! / I ,�I;7'1 , Pr, �, �) '�\ •� ttC�`1;�. �aJ. I 1 t t 1 I i I 1 iCCC» .,�Q i I i i I I I � �• � 1 � I ,I� t ' �6 ? 1 ; 1` � `.0.C\ g5.p ': t �� ��•r q ri 4r, I II , 1 , _ , , , , { N � •�' I �� -r - ,� - ' I •O. I � I I I �I � ' 1, I I� \ ' ,\ �i, T.. s e ; I 6A� L "kA� •c� ;�, I I. I ,I 1 I i ,i i ,Ir \, , �` ' 1 I ..6 _:o , 8 w•Mii �,... I t t Irk• r - ! �, •'�,U'rK , �/► /091;�r3 -1►.fQ.BB � I i= }}--yy � � � 9� �' - , E� .•', I j I / � ;�y:nxii°ior_ . ccs " ,s•c s`•. a ', c� � `' � dF ; ns ' �I.I7�� o�S O � •i ' - - -\ � � 8 I •1 , '!s r/ ti 99[r a. :,r.:� ...�1 ��"; I 11 �, � PP�°` I- •; Iljii �< --I IT, at6 � :6� gl � I ` ,}� 1 I I a ,- _ , � ! �-�FAQ"', �� I 1, ' , i I i'�I,. �� •.I ' s� � y;' 'I. !1'� �.•ti m� � ���- � � �O iF.! aj'• 1 I �[ I � , ! r I _ � �u �� � I +� �'- �.` 1 �, 1 �lu l; ,� �!i'V..., I� o '� � _... 11, m � V e-1' 6 •'��I 1 -'�I A 1 I I AI �� � r i I' I , 1 , ' 1 I , 1 // � .i.�„ .If .1!,j_LL ° .i1 , // •r� I1111 ,I r 1 , I 1 1 L1 t - Z .a FFA' r FA m FtA P m I' F KP•m -tPs�� ! p4 5F to '♦ 5Fpp� 7TylN� Te Tt o File Basin Hydrograph Storage Discharge Level pool 3eee5eeeeeeeeeeeeeeeee�eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; eeeeeeeeee ; ° ° SHEE�ELOW CALCULATOR - INITIAL 300 FEET ° ° ° ° ° ° °DES°Mannings Sheet Flow. . . . . : n300 . 00 ° °ARE°Flow Length (ft) . . . . . . . . : CHOICES oOPAI°2 yr 24 hr rainfall (in) :°TIM°Land Slope (ft/ft) . . . . . . . ° ° °TIM° COMPUL TIME (min) :( 21 . 44 ° o °RAI° TYPICAL MANNINGS VALUES FOR INITIAL 300 FT °A ° °ABS° ° ° °BAS°Smooth Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 011 ° ° °STO°Fallow Fields of Loose Soil Surface . . . . . . . . . . . . . . : 0 . 05 °Y ° °Cultivated Soil with residue cover (s<=0 . 2 ft/ft) : 0 . 06 0 ° °PER°Cultivated Soil with residue cover (s>0 . 2 ft/ft) . : 0 . 17 0 ° °ARE°Short prairie grass and lawns . . . . . . . . . . . . . . . . . . . . : 0 . 15 0 ° °CN °Dense grasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 24 ° ° ° °Bermuda grass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 41 ° ° ° °Range (natural) . . . . . . . . . . .7. , . . . . . . . . . . . . . . . A- I . . . . .0 . 13 ,,° ° �u °PEA°Woods or forest with light underbrush. . . . . . . . . . . . : 0 .40 ° °PEA°Woods or forest with dense underbrush. . . . . . . . . . . . : 0 . 80 ° ° °TOT° ° ° 00F10Key: QUIT F5Key: CLEAR °ete ° Pgaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeefit ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef File .,Basin Hydrograph Storage Discharge Level pool 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° INPUT, MODIFY OR BROWSE DATA ° ° 5eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° °DES° SHALLOW CONCENTRATED FLOW CALCULATOR ° ° °ARE° --- ° ° °RAI°Flow Length (ft) . . . . 350 .00 ° °TIM°Land Slope (ft/ft) . : ( 0 . 1630 ) C Z ° ° °TIM°Kc, Velocity Factor. 1 3 . 0_ o ° °RAI° �-""� COMPUTED TRAVEL TIME (min) : 4 . 82 ° ° °ABS° TYPICAL VELOCITY FACTOR VALUES - R=0 . 1 ° °BAS° ° ° °STO°Forest with heavy ground litter and meadows (n=0 . 10) . . 3 0 ° ° °Brushy ground with some trees (n=0 . 060) . . . . . . . . . . . . . . : 5 ° ° °PER°Fallow or minimum tillage cultivation (n=0 . 04) . . . . . . . : 8 0 ° °ARE°High grass (n=0 . 035) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 0 ° °CN °Short grass, pasture and lawns (n=0 . 030) . . . . . . . . . . . . . : 11 0 ° ° °Nearly bare ground (n=0 . 025) . . . . . . . . . . . . . . . . . . . . .. . . .. . . 13 ° ' .n ° °Paved and gravel areas (n=0 . 012) . . . . . . . . . . . . . . . . . . . . . : 27 ° ° °PEA° ° ° 0PEA0F10Key: QUIT -F5Key: CLEAR ° ° °TO,Taeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef ° ° HOME END ,Fl : Find F2 :New F3 :Get F4 :Tc-Cale F5 :Delete °. _ ° Pgup Pgdn F6 :Compute F7 : F8 :Method F9 :Template F10 :Exit ° a eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef File Basin Hydrograph Storage Discharge Level pool 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° INPUT, MODIFY OR BROWSE DATA ° ° BASIN ID A10 SBUH HYDROGRAPH ° °DES4eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° °ARE° TIME OF CONC WORKSHEET °NFALL CHOICES 0 7/21/96 Jaeger Engineering page 1 O' Connor Plat drainage Analysis Predeveloped Drainage-Stiegman BASIN SUMMARY BASIN ID: D10 NAME: Predeveloped, Stiegman, 10 yr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 .52, .52, Acres BASEFLOWS : . 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 1 . 52 Acres TIME- INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 TIME ' OF CONC. . . . . : 31 . 69 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 00 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 250 . 00 ns : 0 .4000 p2yr: 2 . 00 s : 0 . 0850 PEAK..- RATE : 0 . 27 cfs VOL: 0 . 16 Ac-ft TIME : 480 min BASIN ID: D100 NAME: Predeveloped, Stiegman, 100 yr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 . 52 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 1 . 52 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 31 . 69 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 00 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 250 . 00 ns : 0 . 4000 p2yr: 2 . 00 s : 0 . 0850 PEAK RATE : 0 . 51 cfs VOL: 0 . 26 Ac-ft TIME : 480 min BASIN ID: D2 NAME: Predeveloped, -Stiegman, 2 yr SBUH, METHODOLOGY TOTAI, AREA. . . . . . . : 1 . 52 Acres BASEFLOWS : 0 . 00 cfs _ RAINFALL TYPE . . . . : USERI PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 1 . 52 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 TIME 'OF CONC. . . . . : 31 . 69 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 00 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 250 . 00 ns : 0 . 4000 p2yr: 2 . 00 s : 0 . 0850 PEAK RATE : 0 . 10 cfs VOL: 0 . 08 Ac-ft TIME: 490 min File Basin Hydrograph Storage Discharge Level pool 3eee5eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; eeeeeeeeee; ° ° SHEET FLOW CALCULATOR - INITIAL 300 FEET ° ° 0 0 ° 0 °DES°Mannings Sheet Flow. . . . . : 0 . 4000 ° ° °ARE°Flow Length (ft) . . . . . . . . : 250 . 00 °HOICES ° °RAI02 yr 24 hr rainfall (in) : 2 . 00 ° u , ° °TIM°Land Slope (ft/ft) . . . . . . : 0 . 0850 ° ° °TIM° COMPUTED TRAVEL TIME (min) : 31 . 69 ° ° °RAI° TYPICAL MANNINGS VALUES FOR INITIAL 300 FT °A ° °ABS° 1 ° ° °BAS°Smooth Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 011 ° ° °STO°Fal-low Fields of Loose Soil Surface . . . . . . . . . . . . . . : 0 . 05 °Y ° ° 'Cultivated Soil with residue cover (s<=0 . 2 ft/ft) : 0 . 06 ° ° °PER°Cultivated Soil with residue cover (s>0 . 2 ft/ft) . : 0 . 17 ° _ ° °ARE°Short prairie grass and lawns . . . . . . . . . . . : 0 . 15 ° °CN °Dense grasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . : 0 . 24 0. ° 0 °Bermuda grass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 41 0 0 • °Range (natural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 13 0 0 °PEA°Woods or forest with light underbrush. . . . . . . . . . . . : 0 . 40 0 ° °PEA°Woods or forest with dense underbrush. . . . . . . . . . . . : 0 . 80 ° ° °TOT° 0 0 00F10Key: QUIT FSKey: CLEAR °ete ° Pgaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeefit ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef TC IV. DEVELOPED DRAINAGE CONDITIONS The developed project will include a piped drainage system that will collect a]_1 of the runoff from the proposed roads . Each lot will also be provided with a drainage stub for connection to the gutters and footing drains . The piping from the developed site will discharge into a concrete, subsurface detention vault . This vault will be divided with a baffle wall to provide a two-cell storage structure . The vault will be sized to handle the 2 , 10 and 100 year storm events . It will discharge into a grass-lined biofiltration swale that is located adjacent to the vault . The configuration of the plat is such that a number of lots cannot drain into the vault . These are the lots along the low, western plat boundary. Because of this, these lots will be considered as developed bypass flow. Their respective developed flows will be subtracted .f rom the vault' s allowable release rate for each storm. These are Lots # 29 through # 36 . It is anticipated that there will be three lots in the adjacent Stiegman short plat that will not be able to drain into the storage facility for that short plat . Because this vault can probably mitigate the bypass from these offsite lots better than the anticipated underground pipe, these lots will also be added to the bypass flow. The developed area that drains into the pond must also be adjusted to account for fringe roadways . There is a 72 ft . length of S.. 34th St . next to the vault that cannot drain into the vault . This will not be added to the bypass because the flow will continue down the gutter and be caught by the storage system in the Stiegman plat . Its area will be added to that system. There is also a portion of 104th Ave . SE at the SE corner of the plat that will drain into the plat' s road and drainage system. This area should be added to the developed area at this time . These area calculations are shown on the following worksheet . Similar to the predeveloped drainage analysis, the developed drainage and the bypass were calculated using the SBUH hydrograph method. The computer data sheets are attached. A summary of the developed drainage characteristics are : STORAGE BYPASS Time of concentration: 13 . 32 min. 7 . 12 min. 2 year peak flow: 2 . 74 CFS 0 . 46 CFS 10 year peak flow: 4 . 57 CFS 0 . 76 CFS 100 year peak flow: 6 . 69 CFS 1 . 11 CFS pervious area : 4 . 93 Ac . 0 . 75 Ac . impervious area : 4 . 37 0 . 66 pr--\«-wPe-b PRA iQP-(SE NJNLN51s So VY1 e_ s l�U' O nor Or � t t �o I �O�' t T� �e.�,�, ���v� no �,b r o-� �. 10 - vU t. t4 ,Y, 3 w�I t S+1�- �\�) ��o r l' P� �-I vv Cry VA 0 1 6 2 3 lots- w t I c Jj-,o be- ce- n Zf 6 Pass C)4 w t i l b�P- �- J- 4Z_ -I ci-s - O cty,t,V,0\r 3 z 13 31 35 , 3� Lo(DI QL3 4 Co 4-, t>000 4sZD0 Y 3 (ofi,:5 too"Lc I oo' e-o- = 106COO ST a .41 �. 1 ,0 Pic- 4-1 o ccmv,,o V- sE C-4D r-1,I" - so 15 _ -7 1 -7 4c C, OD sF 012> 6c. C�Yta,\vn s +1c, no _ - --- , Cure c- C�) fDicd A =7 I cov 10, Zi Vic. Co ��2 4�(9 ,3 = 4. 37 �� �VIOU- ,53(g.3 = 4,1 f�c 2J� 13y Puss : 1 er�li�� 470 41 = C� o(o Ac- 3 Vit-OE o rs c NTRI�T 1�� 1 ( ��ow ,n� v&0 1-� Tc l o Pt. s ,ycll-�J ( Lo+ �Q #4-4- - � ��,�I � slq _ , s /o fic -7�o . ogre.� sl�P� �-F ►o% Tc 7- C� 1 G 3 = Zo O �^-POW B- © ,S% S ' Ct) �} , TlMF t= C-NCE� TR" O�.! vn � o-F S�s�-# �aw o�rQ-r' a,- s Ln , z' 1 7/21/96 Jaeger Engineering page 1 O' Connor Plat drainage Analysis Developed Hydrographs --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: B10 NAME: Developed, 10 year, 24 hr u SBUH METHODOLOGY TOTAL AREA. . . . . . . : 9 . 30 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 4 . 93 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 13 . 32 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 4 . 37 Acres CN. . . . : 98 .,00 , . TcReach - Sheet L: 110 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0450 - TcReach - Channel L: 700 . 00 kc : 42 . 00 s : 0 . 1000 TcReach - Channel L: 200 . 00 kc : 17 . 00 s : 0 . 0050 PEAK RATE: -4 . 57 cfs VOL: 1 . 62 Ac-ft TIME : 480 min BASIN ID: B100 NAME: Developed, 100 year, 24 hr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 9 . 30 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 4 . 93 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 13 . 32 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 4 . 37 Acres CN. . . . . 98 . 00 TcReach - Sheet L: 110 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0450 TcReach - Channel L: 700 . 00 kc :42 . 00 s : 0 . 1000 TcReach - Channel L: 200 . 00 kc : 17 . 00 s : 0 . 0050 PEAK RATE : 6 . 69 cfs VOL: 2 . 34 Ac-ft TIME : 480 min BASIN ID: B2 NAME : Developed, 2 year, 24 hr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 9 . 30 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 4 . 93 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 13 . 32 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 4 . 37 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 110 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0450 TcReach - Channel L: 700 . 00 kc: 42 . 00 s : 0 . 1000 TcReach - Channel L: 200 . 00 kc : 17 . 00 s : 0 . 0050 PEAK RATE: 2 : 74 cfs VOL: 0 . 99 Ac-ft TIME : 480 min Tc. T m f— o `: File Basin Hydrograph Storage Discharge Level pool 3eee5eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; eeeeeeeeee ; ° SHEET FLOW CALCULATOR - INITIAL 300 FEET ° ° 0 0 - ---'-- 0 0 °DES°Mannings Sheet Flow. . . . . : L2 . 00 00 ° ° °ARE°Flow Length (ft) . . . . . . . . : 00 IC 1 °HOICES ° °RAI02 yr 24 hr rainfall (in) ° ° °TIM°Land Slope (ft/ft) . . . . . . . 50 ° °°TIM° COMPEL TIME (min) : 9 . 67 ° ° °RAI° TYPICAL MANNINGS VALUES FOR INITIAL 300 FT °A ° °ABS° ° °BAS°Smooth Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . : 0 . 011 ° ° °STO°Fallow Fields of Loose Soil Surface . . . . . . . . . . . . . . : 0 . 05 °Y ° °Cultivated Soil with residue cover (s<=0 . 2 ft/ft) : 0 . 06 ° ° °PE,R0,Cultivated Soil with residue cover (s>0 . 2 ft/ft) . : 0 . 17 ° ° °ARE°Short prairie grass and lawns . . . . . . . . . . . . . . . . . . . . : 0 . 15 0 -° °CN °Dense grasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 24 ° ° 0 °Bermuda grass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 41 0 ° ° °Range (natural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 13 ° ° °PEA°Woods or forest with light underbrush. . . . . . . . . . . . : 0 . 40 0 ° °PEA°Woods or forest with dense underbrush. . . . . . . . . . . . : 0 . 80 0 ° °TOT° ° ° 11F10Key: QUIT F5Key: CLEAR °ete ° Pgaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeefit ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef File Basin Hydrograph Storage Discharge Level pool 3eee5eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ee ; ° CHANNEL FLOW CALCULATOR 0 ° 0 0 _ 0 0 °DES°Flow Length (ft) . . . . 700 . ° ° °ARE°Land Slope (ft/ft) . . 0 . 100 _TGZ 0 ° °RAI°Kc, Velocity Factor: 42 . ° ° °TIM° COMPUTED TRAVEL TIME (min) : (0D. 88 ° ° °TIM° TYPICAL VELOCITY FACTOR VALUES ° ° 0RAI0 0 0 °ABS° Intermittent Flow - R=0 . 2 ° ° °BAS°Forested swale" w/ heavy ground litter (n=0 . 10) . . . . . . . . . . . . . . . . . : 5 1 ° °STO°Forested drainage course/ravine w/ defined channel bed (n=0 . 50) : 10 0 ° °Rock-lined (n=0 . 035) . . . : 15 Grassed (n=0 . 030) . . . : 17 0 ° °PER°Earth-lined (n=0 . 025) . . : 20 CMP pipe (n=0 . 024) . . : 21 ° ° °ARE°Concrete pipe (n=0 . 012) : 42 other. . . . . . . . . . . 0 . 508/n 0 ° °CN ° Continous Flow - R=0 . 4 0 ° ° °Meandering stream w/ some pools (n=0 . 040) . . . . . . . . . . . . . . . . . . . . . . : 20 0 ° • 'Rock-lined stream (n=0 . 035) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "". . :u '.23 ° ° °PEA°Grassed-lined stream (n=0 . 030) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 0 ° °PEA°Other streams, man-made channels and pipe . . . . . . . . . . . . . . . . . : 0 . 807/n °..-. ° °TOT° . , ° ° 00F10Key: QUIT F5Key: CLEAR ° ° ° Pgaeeeeeeeeeeeeeeeeeeeeeeeee��eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef File -Basin Hydrograph Storage Discharge Level pool 3eee5eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ee ; ° 0 CHANNEL FLOW CALCULATOR 0 10 0 0 0 0 °DES°Flow Length (ft) . . . : 200 . 00 ° °ARE°Land Slope (ft/ft) . : 0 . 0050 ° °RAI°Kc, Velocity Factor: 17 . 0 ° °TIM° COMPUTED TRAVEL TIME (min) : 2 . 77 ° ° �°TIM° TYPICAL VELOCITY FACTOR VALUES o 0 °RAI° TC3 0 0 °ABS° Intermittent Flow - R=0 . 2 ° ° °BAS°Forested swale w/ heavy ground litter (n=0 . 10) : . . . . . . ... . . . . . . . . : 5 ° ° °STO°Forested drainage course/ravine w/ defined channel bed (n=0 . 50) : 10 0 ° °Rock-lined (n=0 . 035) . . . : 15 Grassed (n=0 . 030) . . . : 17 ° ° °PER°Earth-lined (n=0 . 025) . . : 20 CMP pipe (n=0 . 024) . . : 21 0 ° °ARE°Concrete pipe (n=0 . 012) : 42 other. . . . . . . . . . . 0 . 508/n 0 ° °CN ° Continous Flow - R=0 . 4 0 ° • °Meandering stream w/ some pools (n=0 . 040) 20• ° °Rock-lined stream (n=0 . 035) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 0 ° °PEA°Grassed-lined stream (n=0 . 030) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 0 ° °PEA°Other streams, man-made channels and pipe . . . . . . . . . . . . . . . . . : 0 . 807/n 0 ° °TOT° 0 0 00F10Key: QUIT FSKey: CLEAR ° ° Pgaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef 7/21/96 Jaeger Engineering page 1 O' Connor Plat drainage Analysis Bypass Drainage Hydrographs --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: C10 NAME : Developed, bypass 10 yr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 . 41 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 . 75 Acres TIME INTERVAL. . . . . 10 . 00 min CN. :': . : 86 . 00 TIME, OF CONC. . . . . : 7.. 12 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 66 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0800 PEAK RATE : 0 . 76 cfs VOL: 0 . 25 Ac-ft TIME : 480 min BASIN ID: C100 NAME : developed, bypass, 100 year SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 .41 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 75 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 7 . 12 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 66 Acres CN. . . . : 98 . 00 PEAK RATE: 1 . 11 cfs VOL: 0 . 36 Ac-ft TIME: 480 min BASIN ID: C2 NAME : Developed, bypass, 2 yr . SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 . 41 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 75 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC . . . . . : 7 .12 min IMPERVIOUS AREA ABSTRACTION "COEFF: 0 . 20 AREA. . : 0 . 66 Acres CN. . . . . 98 . 00 PEAK, PATE: 0 . 46 cfs VOL: 0 . 15 Ac-ft TIME : 480 min File Basin Hydrograph Storage Discharge Level pool 3eee5eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; eeeeeeeeee; ° SHEET FLOW CALCULATOR - INITIAL 300 FEET 0 ° ° ° ° ° °DES°Mannings Sheet Flow. . . . . : 0 . 1500 ° ° °ARE°Flow Length (ft) . . . . . . . . : 100 . 00 °HOICES ° °RAI02 yr 24 hr rainfall (in) : 2 . 00 ° ° °TIM°Land Slope (ft/ft) . . . . . . : 0 . 0800 ° ° °TIM° COMPUTED TRAVEL TIME (min) : C. 12 ° ° °RAI° TYPICAL MANNINGS VALUES FOR INITIAL 300 FT °A ° °ABS° ° ° °BAS°Smooth Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 011 ° ° °STO°Fallow Fields of Loose Soil Surface . . . . . . . . . . . . . . : 0 . 05 °Y ° ° 'Cultivated Soil with residue cover (s<=0 . 2 ft/ft) : 0 . 06 0 ° °PER°Cultivated Soil with residue cover (s>0 . 2 ft/ft) . : 0 . 17 ° ° °ARE°Short prairie grass and lawns . . . . . . . . . . . . . . . . . . . . : 0 . 15_<— ° ° °CN °Dense grasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . : 0 . 24 0 ° • °Bermuda grass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 41 ° ° ° °Range (natural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 13 ° ° °PEA°Woods or forest with light' underbrush. . . . . . 0 . 40 b ° °PEA°Woods or forest with dense underbrush. . . . . . . . . . . . : 0 . 80 0 ° °TOT° • ° ° °OF]_OKey: QUIT F5Key: CLEAR °ete ° Pgaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeefit ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef File Basin Hydrograph Storage Discharge Level pool 3eee5eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; eeeeeeeeee ; ° ° SHEET FLOW CALCULATOR - INITIAL 300 FEET 0 ° ° ° ° ° °DES°Mannings Sheet Flow. . . . . : 0 . 1500 0 ° °ARE°Flow Length (ft) . . . . . . . . : 100 . 00 °HOICES ° °RAI02 yr 24 hr rainfall (in) : 2 . 00 ° ° °TIM°Land Slope (ft/ft) . . . . . . . 0 . 0700 ° ° °TIM° COMPUTED TRAVEL TIME (min) : 7 . 51 ° ° °RAI° TYPICAL MANNINGS VALUES FOR INITIAL 300 FT °A ° °ABS° ° ° °BAS°Smooth Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 011 ° ° °STO°Fallow Fields of Loose Soil Surface . . . . . . . . . . . . . . : 0 . 05 °Y ° ° °Cultivated Soil with residue cover (s<=0 . 2 ft/ft) : 0 . 06 0 ° °PER°Cultivated Soil with residue cover (s>0 . 2 ft/ft) . : 0 . 17 0 ° °ARE°Short prairie grass and lawns . . . . . . . . . . . . . . ,. . ., . . . : 0 . 15 ° ° °CN °Dense grasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 24 0 ° ° °Bermuda grass . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 0 .41 ° ° • °Range (natural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 13 ° ° °PEA°Woods or forest with light underbrush. . .. . . . . . . . . . : 0 . 40 0 ° °PEA°Woods or forest with dense underbrush. . . . . . . . . . . . : 0 . 80 0 ° °TOT° ° ° 00F10Key: QUIT FSKey: CLEAR °ete ° Pgaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeefit ° a66666eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee2e222e222e22ee2ee2eeeeeeee2222f 7/21/96 Jaeger Engineering page 1 O' Connor Plat drainage Analysis Developed Hydrographs-Stiegman --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: E10 NAME : Developed, Stiegman, 10 yr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 . 20 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AR9A.'. : 0 . 64 Acres TIME INTERVAL . . . . : 10 . 00 min CN. . . . : 86 . 00 TIME. OF CONC. . . . . : 7 . 51 min IMPERVIOUS AREA 'ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 56 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 10Q , 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0700 PEAK RATE: 0 . 64 cfs VOL: 0 . 21 Ac-ft TIME : 480 min f BASIN ID: E100 NAME: Developed, Stiegman, 100 yr SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 . 20 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 64 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 7 . 51 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 56 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0700 PEAK RATE: 0 . 94 cfs VOL: 0 . 30 Ac-ft TIME: 480 min BASIN ID: E2 NAME: Developed, stiegman, 2 year SBUH METHODOLOGY 1. TOTAL AREA. . . . . . . : 1 . 20 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . . USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 64 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 7 . 51 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 .. AREA. . : 0 . 56 Acres CN. . . . : 98 . 00 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0700 PEAK RATE: 0 . 39 cfs VOL: 0 . 13 Ac-ft TIME : 480 min C (I 0� V. DETENTION STORAGE The required drainage detention will be provide by 'a concrete subsurface vault . The vault performance was determined by routing a level pool analysis through a defined storage structure and a defined flow restrictor. The results are shown on the- attached worksheet and computer summary sheets . The results show that the vault will met the required performance for each storm event . It actually discharges less than the allowable rate for the 10 and 100 year storms . The vault also provides some excess storage volume . This will allow additional freeboard for the 100 year storm. 1 ------------- Z yr 1� 04 cis I(�yr 2. �3' c, 1 o 1c, 4-(oIo 100 3 M o w"I I0 yr- Z , +3 - 0,-1(0 = i Co CFS c� (oc) Yr. 4- , ZI - 1 , 11 = 3 , 10 c,F-3- o.�. 2 yr O, s IFS 10 �,-. ( L (9 3 C'�--s 2 \\)O-u Was C k-Rf\04 CLSy t - ..w 111 Le .P v ro t 04J , I .k (9 MQ w�I I �a-ue- e b e 9 , vc-ij (+ w (11 6e- -? - . File Basin Hydrograph Storage Discharge Level pool Jaeger Engineering 2eeeeeeeeeeeeeeeee ; 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° ROUTING COMPARISON TABLE ° ° MATCH INFLOW STO DIS PEAK PEAK OUT ° ° DESCRIPTION PEAK PEAK No . No. STG OUT HYD ° ---------------------------------------------------------------------- °2 year 0 . 00 2 . 74 1 1 237 . 64 0 . 58 11 ° 010 year 0 . 00 4 . 57 1 1 ' 238 . 61' 1 . 63 ''12 'u.. ° 0100 year 0 . 00 6 . 69 1 1 239 . 89 3 . 06 13 0 ° ° ° ° ° ° ° ° ° ° ° ° Oi ° ° ° ° ______====>Done<====_______= F10 to Exit °i aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef Available Memory remaining: 170040 bytes Current Data Set Name : \OCONNER.bsn 7/21/96, Jaeger Engineering page 1 O' Connor Plat drainage Analysis Level Pool Routing --------------------------------------------------------------------- --------------------------------------------------------------------- LEVEL POOL TABLE SUMMARY MATCH INFLOW ST DI <-PEAK-> STORAGE <- - - - --- -DESCRIPTION-------- -> (cfs) (cfs) id id <-STAGE> id VOL (cf) ----------------------------------------------------------------------- ----------------------------------------------------------------------- 2 year 0 . 00 2 .�74 1 1 237 . 64 11 12329 . 18 10 year . . . . . . . . . . . . . .. . . . . . . . . 0 . 00 4 . 57 1 1 238 . 61 -12 16803 . 33 :'O1 100 'year . . . . . . . . . . . . . . . . . . . . . 0 . 00 6 . 69 1 1 239'. 89 13 22666 File Basin Hydrograph Storage Discharge Level pool J2eeeeeeeeeeeeeeeeeeeeee ; ° ° °Rectangular vault ° °Trapezoidal basin 0 °Underground pipe ° 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° TRAPEZOIDAL BASIN ° ° STORAGB STRUCTURE ID: 1 ° o ° °Name : Onsite Detention Vault ° °Length. . . . . . . . . . . 69 . 50 Width. . . . . . . . . . . 66 . 00 ° ° Length Sslope 1 : 0 . 00 Width Sslope 3 : 0 . 00 ° Length Sslope 2 : 0 . 00 Width Sslope 4 : 0 . 00 ° °Infiltration Rate . . : 0 . 00 ° °Starting Elevation. : 234 . 95 ° °Max Elev of Basin-; 240 . 45 Lj- ° °Stage-Sto Increment : 0 . 10 ° °Structure Vol (cf) . : 25228 . 50 S-Tp-o c-IL)R� Ac-ft . : 0 . 58 ° ° ° ° ° °PGUP PGDN F3 : Get F6 : Delete F10 : Exit ° Avaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef Current Data Set Name : \OCONNER.bsn File Basin Hydrograph Storage Discharge Level pool 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° MULTIPLE ORIFICE ° ° DISCHARGE STRUCTURE ID: 1 ° o ° °Name : Vault flow restrictor ° °Peak Dsgn Release Rate : 3 . 46 cfs Orif /flow/elev ° °Orifice Coefficient . . . : -0 .62 Dia:. (in) /cfs/ ft u° °Lowest Orifice Dia (in) . . . 3 . 60 3 . 60 0 . 78 cfs Ohl : Outlet to 2nd Orifice : 2 . 75 237 . 70 ft ° °Second Orifice Dia (in) . . . 6 . 00 6 . 00 1 . 45 cfs ° 0h2 : 2nd to 3rd Orifice . . . : 0 . 95 238 . 65 ft ° °Third Orifice Dia (in) . . . 5 . 25 5 . 25 0 . 83 cfs ° °h3 : 3rd to 4th Orifice . . . : 0 . 00 ° °Fourth Orifice Dia (in) . . : 0 . 00 ° °,h4 : 4t4 to 5th Orifice . . . : 0 . 00 ° °Top Orifice Dia (in) . . . 0 . 00 W ° ° ° °Elevation of Lowest Orifice . . . . : 232 . 95 R� � �C-WRO °Outlet Elevation. . . . . . . . . . . . . . . : 234 . 95 ° °Max Elev Above Outlet . . . . . . . . . . : 239 . 89 ° °Stage-Disch Increment . . . . . . . . . . : 0 . 10 ° ° ° Av°PGUP PGDN F3 : Get F6 : Delete F10 : Exit ° Cuaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef 7/21/96 Jaeger Engineering page 1 O' Connor Plat drainage Analysis Vault Stage-Storage Table --------------------------------------------------------------------- --------------------------------------------------------------------- STAGE STORAGE TABLE TRAPEZOIDAL BASIN ID No. 1 Description: Onsite Detention ault Length: 69 . 50 ft . Width: 66 . 00 ft . " Side Slope 1 : 0 Side Slope 3 : 0 Side Slope 2 : 0 Side Slope 4 : 0 Infiltration Rate : 0 . 00 in/hr .. .. STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --AC-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- 234.95 0.0000 0.0000 236.40 6651 0.1527 237.90 13532 0.3106 239.40 20412 0.4686 235.00 229.35 0.0053 236.50 7110 0.1632 238.00 13990 0.3212 239.50 20871 0.4791 235.10 608.OS 0.0158 236.60 7569 0.1737 238.10 14449 0.3317 239.60 21330 0.4897 235.20 1147 0.0263 236.70 8027 0.1843 238.20 14908 0.3422 239.70 21788 0.5002 235.30 1605 0.0369 236.80 8486 0.1948 238.30 15366 0.3528 239.80 22247 0.5107 235.40 2064 0.0474 236.90 8945 0.2053 238.40 15825 0.3633 239.90 22706 0.5212 . 235.50 2523 0.0579 237.00 9403 0.2159 238.50 16284 0.3738 240.00 23164 0.5318 235.60 2982 0.0684 237.10 9862 0.2264 238.60 16743 0.3844 240.10 23623 0.5423 235.70 3440 0.0790 237.20 10321 0.2369 238.70 17201 0.3949 240.20 24082 0.5528 235.80 3899 0.0895 237.30 10779 0.2475 238.80 17660 0.4054 240.30 24540 0.5634 235.90 4358 0.1000 237.40 11238 0.2580 238.90 18119 0.4159 240.40 24999 0.5739 236.00 4816 0.1106 237.50 11697 0.2685 239.00 18577 0.4265 240.45 25228 0.5792 236.10 5275 0.1211 237.60 12156 0.2791 239.10 19036 0.4370 236.20 5734 0.1316 237.70 12614 0.2896 239.20 19495 0.4475 236.30 6192 0.1422 237.80 13073 0.3001 239.30 19953 0.4581 7/21/96 . Jaeger Engineering page 1 O' Connor Plat drainage Analysis Vault Stage-discharge table v --------------------------------------------------------------------- ----------------------------------------------------------=---------- STAGE DISCHARGE TABLE MULTIPLE ORIFICE_ ID No. 1 Description: Va t flow restric o Outlet Elev: 234 . 95 Elev: 232 . 95 ft Orifice Diameter: 3 . 6000 in. Elev: 237 . 70 ft Orifice 2 Diameter: 6 . 0000 in. Elev: 238 . 65 ft Orifice 3 Diameter: 5 . 2500 in. STAGE <--DISCHARGE---> STAGE <--DISCHARGB---> STAGE <--DISCHARGB---> STAGE <---DISCHARGE---> (ft) ---cfo-- ------- (ft) ---cfS-- ------- (ft) ---cfo-- ------- (ft) ---cfs-- ------- ------------------------------------------------------------- 234.95 0.0000 236.20 0.3932 • 237.50 0.5616 238.80 2.0044 235.00 0.0786 236.30 0.4086 237.60 0.5725 238.90 2.1431 235.10 0.1362 236.40 0.4235 237.70 0.5832 239.00 2.2641 235.20 0.1758 236.50 0.4379 237.80 0.9027 -"" 239.10 2.3741. 235.30 0.2081 236.60 0.4518 237.90 1.0410 239.20 2.4762 235.40k 0.2359 236.70 0.4652 238.00 1.1493 239.30 2.5723 . 235.50 0.2608 236.80 0.4784 238.10 1.2421 239.40 2.6634 235.60 0.2835 236.90 0.4911 238.20 1.3248 239.50 2.7505 235.70 0.3046 237.00 0.5036 238.30 1.4004 239.60 2.8340 235.80 ' 0.3242 237.10 0.5157 238.40 "1.4706 239.70 2.9145 235.90 0.3428 237.20 0.S27S 238.50 1.5364 239.80 2.9923 236.00 0.3604 237.30 0.5391 238.60 1.5987 239.89 3.0603 236.10 0.3772 237.40 0.5505 238.70 1.8252 File Basin Hydrograph Storage Discharge Level pool Jaeger Engineering 2eeeeeeeeeeeeeeeee ; 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° ROUTING COMPARISON TABLE ° ° MATCH INFLOW STO DIS PEAK =PEAK OUT ° ° DESCRIPTION PEAK PEAK No. No . STG OUT HYD ° ---------------------------------------------------------------------- °2 year 0 . 10 0 . 39 2 2 222 . 81 0 . 10 11 ° 010 year 0 . 27 0 . 64 2 2 223 . 65 0 . 27 12 0 0100 year 0 . 51 0 . 94 2 2 224 . 80 0 . 51 13 0 ° ° ° 011V el D ev,) �o 0T� ° ° ° ° ° ° ° ° ° ° ° ° ° ______====>Done<====_______= F10 to Exit ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef Available Memory remaining: 170040 bytes Current Data Set Name : \OCONNER.bsn 7/22/96 Jaeger Engineering -page 1 ' O'Connor Plat - •- Drainage analysis Level Pool Routing-Stiegman --------------------------------------------------------------------- LEVEL POOL TABLE SUMMARY MATCH INFLOW ST DI <-PEAK-> STORAGE <--- - - -- -DESCRIPTION------ -- -> (cfs) (cfs) id id <-STAGE> id VOL (cf) ----------------------------------------------------------------------- ----------------------------------------------------------------------- 2 year 0 . 10 0 . 39 2 2 ' 222 . 81 11 997 . 06 10 year 0 . 27 0 . 64 2 2 223 . 65 12 1591 . 65 100 year . . . . . . . . . . . . . . . . . . . . . (P0 . 51 0 . 1 2 2 224 . 80 13 2219 . 79 po 1 File Basin Hydrograph Storage Discharge Level pool J2eeeeeeeeeeeeeeeeeeeeee; ° ° °Rectangular vault` u °Trapezoidal basin ° °Underground pipe ° °Sto list ° 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° ° UNDERGROUND PIPE ° ° ° STORAGE STRUCTURE ID: 2 0 ° ° 0eeeeee6f °Name : Rtiegman Detention Pipe ° y.. °Pipe Length (ft) . . . . 180 . 00 ° r, °Pipe Diameter (ft) . : 4 . 00 ° PP f,.� 1(YA 1 � °Pipe Slope (ft/ft) ,. : 0 . 0000 ° °Stage-Sto Increment : 0 . 10 °Starting Elevation : 221 . 00 ° °Structure Vol (cf) . : 2261 . 95 ° ° Ac-ft . : 0 . 05 ° o ° °PGUP PGDN F3 : Get F6 : Delete F10 : Exit ° aeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef Available Memory remaining: 170040 bytes Current Data Set Name : \OCONNER.bsn File Basin Hydrograph Storage Discharge Level pool 3eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ; ° MULTIPLE ORIFICE ° ° DISCHARGE STRUCTURE ID: 2 ° ° ° °Name : Flow Restrictor, Stiegman ° °Peak Dsgn' Release Rate : .0 .51 cfs Orif /flow/elev ° °Orifice Cbefficient . . . : 0 . 62 Dia (in) /cfs/ ft ° °Lowest Orifice Dia (in) . . . 1 . 62 1 . 62 0 . 14 cfs ° Ohl : Outlet to 2nd Orifice : 1 . 85 222 . 85 ft ° °Second Orifice Dia (in) . . : 2 . 50 .. 2 . 50 0 . 24 cfs ° °h2 : 2nd to 3rd Orifice . . . : 1 . 00 223 . 85 ft ° °Third Orifice Dia (in) . . : 2 . 25 2 . 25 0 . 13 cfs ° °h3 : 3rd to 4th Orifice . . . : 0 . 00 ° °Fourth Orifice Dia (in) . . : 0 . 00 ° °h4 : 4th to 5th Orifice . . . : 0 . 00Iv�� �"}rl CZ7� °Top Orifice Dia (in) . . : 0 . 00 ° ° °Elevation of Lowest Orifice . . . . : 219 . 00 �-�-1 rf,\ (,N-of-\ °Outlet Elevation. . . . . . . . . . . . . . . . 221 . 00 °Max Elev Above Outlet . . . . . . . . . . : 224 . 80 ° °Stage-Disch Increment . . . . . . . . . . : 0 . 10 ° ° ° Av°PGUP PGDN F3 : Get F6 : Delete F10 : Exit ° Cuaeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeef BIOFILTRATION SWALE The biofiltration swale was designed using the King County SWM manual criteria . The vegetation type within the swale will be wetland type, as allowed for actual slopes of 0 . 50 or less . This type of swale vegetation specifies a design water depth of 8" within the swale . The bottom width of the swale was determined using the predeveloped 2 year flow. This is allowed since the swal•e is downstream of, the detention pond.- The required bottom width was calculated to be 5 . 78 ft . , with 3 : 1 side slopes . The velocity at these conditions is 0 . 26 FPS,,, less than the max. 1 . 5 FPS . However, the biofiltration swale length will be reduced to 150' and thus the width will be increased proportionally• to 8 . 41 . The swale was also checked for capacity during a 100 year developed flow rate . Its actual slope of 0 . 516 wasused . The resultant depth of flow was 0 . 40 ft . , which would be contained by a 1 ft . deep swale . The computer calculation sheets for the bioswale are attached. Trapezoidal Channel Analysis & Design Open Channel - Uniform flow Worksheet Name : O' Connor Plat Comment : Biofiltration Swale, design cond . , 2 year Solve For Bottom Width Given Input Data: Left Side Slope . . 3 . 00 : 1 (H:V) Right Side Slope . 3 . 00 : 1 (H:V) Manning' s n. . . . . . 0 . 350 Channel Slope . . . . 0 . 0200 ft/ft Depth. . . . . . . . . . . . 0 . 33 ft Discharge . . . . . . . . 0 . 58 cfs Computed Results : Bottom Width. . . . 5 . 78 ft Velocity. . . . . . . . . 0 . 26 fps Flow Area. . . . . . . . 2 . 24 sf Flow Top Width. . . 7 . 76 ft Wetted Perimeter. , , 7 . 87 ft Critical Depth. . . 0 . 07 ft Critical Slope . . . 4 . 4666 ft/ft Froude Number. . . . 0 . 09 (flow is Subcriticsl� -° Open' Channel Flow Module, Version 3 . 12 (c) 1990 Haestad Methods, Inc . * 37 Brookside Rd * Waterbury, Ct 06708 Trapezoidal Channel Analysis & Design Open Channel - Uniform flow Worksheet Name : O' Connor Plat Comment : Biofiltration Swale, actual cond. 100 year Solve For Depth Given input Data : Bottom Width. . . . . 8 . 40 ft Left Side Slope . . 3 . 00 : 1 (H:V) Right Side Slope . 3 . 00 : 1 (H:V) Manning' s n. . . . . . 0 . 030 Channel Slope . . . . 0 . 0050 ft/ft Discharge . . . . . . . . 6 . 69 cfs Computed Results : Depth. . . . . . . . . . . . 0 . 40 ft Velocity. . . . . . . . . 1 . 74 fps Flow Area. . . . . . . . 3 . 84 sf Flow Top Width. . . 10 . 80 ft Wetted Perimeter. 10 . 93 ft Critical Depth. . . 0 . 26 ft Critical Slope . . . 0 . 0213 ft/ft Froude Number. . . . 0 . 52 (flow is Subcritical) Open Channel Flow Module, Version 3 . 12 (c) 1990 Haestad Methods, Inc . * 37 Brookside Rd * Waterbury, Ct 06708 VIL.- OFFSITE DRAINAGE ANALYSIS . A. Analysis of Resources : Several resource materials were reviewed for the preparation of this analysis . These resources' include- 1 . City of Renton general topography maps . 2 . King County sensitive areas folios . 3 . Washington State Dept . of Transportation design plans for SR 515 . 4 . King County drainage investigation problem maps . 5 . City of Renton drainage maps . B. Upstream Off-site Drainage . The upstream off-site drainage onto the site is isolated in one area . SR 515 runs along, or near, the entire eastern property boundary which is the upgradient property line for the site . The drainage system within SR 515 intercepts the runoff from the east and directs it to the north within its conveyance system. There is one area that off-site drainage enters the site . It is very near the southeast corner of existing Lot 1 where a man-made drainage ditch appears at the east property line . It appears that this drainage originates at SE 172 St and is piped under the residential lot at the southeast corner of Lot 1 . The outlet of this culvert begins the ditch. This ditch was never flowing during inspections throughout the summer. The tributary area appears to be small and the ditch can be accommodated within the proposed development by piping the culvert along the west property line and discharging it through a dispersal trench near the southwest corner. C. Downstream Drainage The discharge from the site will be detained and treated prior to discharge . The detention vault will be designed to accommodate the 100 year storm event . A grass-lined biofiltration swale will be constructed adjacent to and downstream from the vault . From the bioswale, the drainage will discharge into a 12" pipe that will run west onto the adjacent property. The pipe will be parallel to the sanitary sewer main, both within a common easement or right-of-way. The pipe will continue to the west for a total of 1650 ft . within three separate offsite lots . It is anticipated that the pipe will be 12" corrugated polyethylene pipe with a smooth interior wall . The slope of the pipe will average between 70-0 and 80 . The pipe will terminate onto Talbot Road. There is an exisitng storm drainage system within the east side of Talbot Road. This drainage system includes six type 1 and type 2 catch basins connected` by 12" concrete pipe . The drainaqt! flow is to" the south along Talbot Road. Just south of S . 172 St ._, an 18" culvert carries. the runoff to the west under Talbot Road. A visual inspection of, the system along Talbot Road did not reveal any problem areas . f y / I - � N 168 J � I r N 167,960.05 E 1,660,342.84 CY pn x- _ h N o p I li N _ 1 I 1 n o I �J I , BRUSH T R E E S _ - - S. 172 ND I ST C U L T I A IT E D � \ x x X F I L 0 ri E " A 26,F3-J tr 26.G3-1 --GY 29,G3-6 A 6,G3-2 - 1 .. A V.l (, 26 3-3 6.1 1 ix V) _-C.>- 26�G3J G 26H3-1 p 26,3-8 6,G3-7 3 O L T •-• ,- Il F- 26,63-4 6H3 o _ -A --i -� f _ M 26N3-3 y ' _r roc 26,r3-t Q ,- F- H ST / 26,G3 5 6 26.C4-2 26.H4-8 26N1 5 En 6,14-0 26C4-3 26,F 4-5 26,G4-1 S 2 TH L 6N4-3 14-7 26,r4-12 6,H1-14 6.1 9 i--� 26,G/-2 _ 6114-1 6.H4- .w£2614-4 -- ,Sa ST PL G 21,rS F 4-13 S G 6,H-6 ..{ .6N1-12 -- ( 26f A-6 O- 26.1- 10 2 14-5 / 26.H1 9 26,F -7 26F-3 26,G4-6 = 6,H4-7 2614-B 26,G1- - • 6,H4- - 6,14 26,14-1 6H�-B S 1/-J 26N�- 26,F4-9 26,G4-4 ^ f� 26,14-2 26,f�-2 26j1-❑ 'Y J -26F4-10 fir.( -- 26,W-5 2M5-7 26,H3- 6,H3-3 6H�-16 „• 26E3-I 6f 4-1 •�.r0 6�- 26,15-6 6,E5-3 6,E 5- 6G5- 26N5-4 2F5-3 26.H5-3 s J ' 26.f5-6 CS6 2613-5 > 26.H5-1 J(. 6113-9 3 ST .15 T D 26,r3-3 26f 5-7 z6ts-7 _ 2613-] 6.H5 a e615/2 26Is 26.r5-2 26G5-3 co 26.r5-1 rn 26F6-B ca 26,r6-6 i'� rn 26r6-5 26r6-7 rn 26f6-4 .6f6-7 •1 70 .. t� t'�1•yC 26,F6-2 26.FG-1 26.46-2 26H6-6 ` . r- � ST 26.E6-3 (Q&0 . 26.H6-7 --_-_-I 26.C7-5 Ir.---" 26.E7-� 26,H6-J 26,H6-B 26,E 7-6 26H7-6 26,C7-7 -- - ------ - -- �- R t6,F7-6 ---. _-. __ 26 H7-7S 172ND ST 2L,C 7-7 26,r 7-2 I to � 26H7-1 S i 13 6--- - -- -- — b I TF{ ST cam, -- V111 EROSION/SEDIMENTATION CONTROL Due to the sensitivity of this site, a significant erosion control plan has been developed. The site sensitivity is caused by the moderately steep slopes, Alderwood type soils subject to erosion and the proximity of a series of downhill wetlands . The basic erosion control measures include the following: 1 . rock pad construction entrance 2 . identified clearing limits _.. 3 . strategically placed silt fencing 4 . hydroseeding and mulching of disturbed areas not being paved. In addition to these primary measures, more significant erosion control facilities include a 6 , 600 cu . ft . sedimentation pond. This sediment pond was designed using the method outlined in the K.C. SWM Manual . A 12" perforated riser pipe will discharge flow from the pond . A network of interceptor ditches, rock check dams and temporary culverts will direct the surface runoff into the pond. The interceptor ditches will be constructed at the sides of future roads throughout the plat . The sediment pond is at the site of the permanent drainage detention pond. The following calculations, diagram and table show the process for designing the sedimentation pond. IJL14 (�OStoN �NT��L C,?4LC-,L) L,41- QrvS= G -Dr MEA—-[T 1Dr--lb- :S l ZA rJ G C 1 Lcs Re .uoreA tcr-ncA volute = I\0 sio ►"C . �lV`n .ems t �1 ��-�- Y O�V VYl�. A Ls • car PR ►�� = c��n�,tea) s����-t Y�of� C.i�S/� Z,-zz (Z,�� Z.z _ fin, Z o lL So I l A;- roCj C. O , 15 A-I'�w o cd .so t I z, T-"le C � L CQ o0 Ls CN = � -��- 1 .0 ( sQ.-}- 6 Y P -Pam-C--f i e e._ blf 2• Tb-J,,l h,,, 1 v Le... dlr�c� r v,� ZOO (Qa� = Art-ems. " 5e = 4 ,4 L 4- ► . 3 4 �o1c9v _ _ 41 ,z.3 q�24- , Lo t=T3 10l0VY`O- se..�k M.e�n-f 2 c�L e, (ems, / S�►- c�. c -2��1�1t 4-0 2 �P y 0 z,n -fit-. fly,) 4-4 C boy ) u, So 3Z , Zsb D • Par, D�s o.� ��o�� �QS ; -}- 2 Sep In Z Pr 4. PI Dv,� �Z" ee_ boa- rz� -� +,n� J 1 v) 1 M v rn M, k re(� I ZS� ( 2 , 3 c�s�j = -3 Fr z La2 'c5Z 3100 , �FTZ �z.. i LJ vnhies fur following siupe lengths f,ft(ml IS values for following siope Icnglhs!,ft(m) 514-1)e gradient IJl 20 :10 10 so 60 70 80 90 100 150 200 250 300 350 400 450 500 600 700 8W 900 lOW w j ratio !3.0) (G.I) (9.1) t12.2) (I5.2) (18.3) (21.:1) (21.4) (27.4) (30.5) (.16) (611 (76) (91) (107) (122) (137) (152) (183) (213) (2,14) (2741 (305) (r 0.5 OAA 001 (W-f_ 0.08 0.08 0.09 O.n9 0.09 0.09 0.10 0.10 0.11 0.11 0.12 0.12 0.13 0.13 0.13 -• 0.1.1 0.14 0.14 0.15 0.15 C I1Nhl I 0.)8 0.09 O.In 0.10 O.II 0.11 0.12 0.12 0.12 0.12 0.1.1 0.1.1 i),IS 0.IG n.ifi 0.In 0.17 0.17 0.18 0.18 0.19 0.19 0.20 ! C Z 1.10 1.12 )14 (J.IS 0.16 0.17 J.18 0.19 0.19 0.20 0.23 0.25 0.26 0.28 0.29 0.30 0.32 0.33 0.:14 0.36 0.37 0.39 0.40 1 0.14 0.18 020 0.22 0.2:! 0.25 0.2G 0.27 0.28 0.29 0.32 0.35 0.38 0.40 0A2 0.43 0.45 0.46 0.49 0.51 0.54 0.55 0.57 -1 0.16 0.•21 0.25 0.28 0.30 U.1 0.35 0.37 Us 0.40 0.47 0.53 0.58 0.62 o.6G 0.70 0.73 0.76 o.82 0.87 0.92 0.96 1.00 , 2u:1 ; 0.11 , 0.24 0.29 0.34 �0.38 0.41 0.45 0.48 0.51 0.53 0.66 0.76 0.85 0.93 1.00 1.07 1.13 1.20 1.31 1.42 1.51 1.60 1.69 C> 0.21 0.30 0.31 0_11:1 0.48 0.52 056 O.60 0.64 0.67 0.82 0.95 1.06 1.16 1.26 1.24 1.,13 1.50 1.65 1.-,,8 1.90 2.02 2.13 > 0.25 0.31 (1.45 0.52 0.58 0.64 0.69 0.7•1 0.78 0.82 1.01 1.17 1.30 1.43 1.54 1.65 1.75 1.84 2.02 2.18 2.33 2.47 2.61 CAI 1 0.31 0.44 0.54 0.63 0.70 0.77 0.83 0.89 0.9.1 0.99 1.21 1.40 1.57 1.72 1.85 198 2.10 2.22 2.43 2.62 2.80 2.97 3.13 .".. 9 (J.:17 o..52 0.64 0.74 0.8.1 0.91 0.98 1.05 1.11 1.17 1.44 1.66 1.85 2.03 2.19 2.35 2.49 2.62 2.87 3.10 3.32 2.52 3.71 -� i � Z 10:1 10 0.43 0.61 0.75 0.87 0.97 1.06 1.15 122 1.30 1.37 1.68 1.94 2.16 2.37 2.56 2.74 2.90 3.06 3.35 3.62 3.87 4.11 4.33 � 0.50 0.71 0.86 1.00 1.12 L22 1.32 1.41 1.50 1.58 1.93 2.23 2.50 2.74 2.95 3.16 3.35 3.53 3.87 4.18 4.47 4.74 4.99 110.61 0.86 1.05 1.22 1.16 1.49 1.61 1.72 1.82 1.92 2.35 2.72 3.04 3.33 3.59 3.84 4.08 4.30 4.71 5.08 5.43. 5.76 6.08 0 0.81 1.14 1.40 1.62 1.91 1.98 2.14 2.29 ^_.43 2.56 3.13 3.62 4.05 4.43 4.79 5.12 5.43 5.72 6.27 6.77 7.24 1.68 8.09 6:1 16.7 0.96 1.36 1.67 1.92 2.15 2.36 2.54 2.72 2.88 3.04 3.72 4.20 4.81 5.27 5,69 6.08 6.45 6.80 7.45 8.04 8.60 9.12 9.62 Z 5:1 20 1.29 1.82 2.23 2.58 2.88 3.16 3.41 3.65 3.87 4.08 5.00 5.77 6.45 1.06 7.63 8.16 3.65 9.12 9.99 10.79 11.54 12.24 12.90 fn 4J4:1 22 1.51 2.13 2.61 3.02 3.37 3.69 3.99 4.27 4.53 4.77 5.84 6.75 7.54 8.26 8.92 9.54 10.12 10.67 11.68 12.62 13.49 14.31 is'08 i C +� 4:1 25 1.86 2.63 3.23 3.73 4.16 4.56 4.93 5.27 5.59 5.89 7.21 8.33 9.31 10.20 11.02 11.78 12.49 13.17 14.43 15.58 16.66 17.67 18.63 :10 2.51 3.56 4.36 5.03 5.62 6.16 6.65 7.11 7.54 7.95 9.74 11.25 12.57 13.77 14.88 15.91 16.87 17.78 19.48 21.04 22.49 23.86 25.15 3:1 3.1.3 2.98 4.22 5.17 5.96 6.67 7.30 1.89 8.43 8.95 9.43 11.55 13.3.1 1.1.91 16.33 17.64 18.86 20.00 21.09 23.10 24.95 26.67 28.29 29.82 35 3.23 4.57 .5.60 6.46 7.23 7.92 8.55 9.14 9.70 10.22 12.52 1•1.46 1G.16 17.70 19.12 20.44 21.68 22.8G 25.04 27.04 28.91 30.67 32.32 C� 2%-1 40 4.00 5.611 6.93 3.00 8.95 9.80 10.59 11.32 1200 12.65 15.50 17.89 '20.01 21.91 23.67 25.30 2G.84 28.29 30.99 33.48 35.79 37.96 40.01 [f� 45 4.81 9.80 8.33• 9.61 10.75 11.77 1272 13.60 14.42 15.20 18.62 21.50 24.03 26.33 28.44 30.40 32.24 33.99 37.23 40.22 42.99 45.60 48.07 j 2:1 50 5.64 7.97 9.76 (1t27 12.60 13.81 14.91 15.9.1 16.91 17.82 21.83 25.21 28.18 .10.87 33.34 35.65 37.81 39.8.S 43.66 47.16 50.41 53.47 56.36 55 6.48 9.16 11.22 12.96 14.48 15.87 17.14 18.32 19.43 20.48 25.09 28.97 .12.39 35.48 38.32 40.97 43.45 45.80 50.18 54.20 37.94 61.45 64.78 IY.:1 57 6.82 9.64 11.80 13.63 15.24 16.69 18.03 19.28 20.45 21.55 26.40 30,48 34.08 37.33 .10.32 13.10 45.72 18.19 52.79 57.02 G0.M. 64.66 68.15 GO 7.32 10.35 12.68 14.64 16.37 17.93 19.37 1.96 '3.15 0.71 2 m = '- = A.35 32.74 3G.60 40.10 43.31 46.30 49.I1 SL77 56.71 61.25 65.48� 69.45 73.21 114:1 66.7 3.44 11.9.1 14.61 16.88 18.87 20.67 2232 23.87 25.31 26.68 32.68 37.74 42.19 46.22 .19.92 53.37 56.60 59.66 65.36 10.60 75.47 30.05 84.38 70 8.98 12.70 15.55 17.96 20.08 21.99 23.75 25.39 26.93 28.39 34.77 40.15 '14.89 49.17 53.11 56.78 60.23 63.48 69.54 75.12 80.30 85.17 89.78 7i 9.78 13.8.1 16.94 19.56 21.87 23.95 25.87 27.66 29.34 30.92 37.87 43.73 48.89 53.56 57.85 61.85 65.60 69.15 15.75 31.82 37.46 92.77 97.79 CAI 1'S:I 80 10.55 14.93 18.28 21.11 2:1.60 25.85 27.93 29.85 31.66 33.38 40.88 47.20 52.77 57.81 62.44 66.75 70.80 74.63 31.76 88.31 94.41 100.13 IM55 85 11.30 15.98 19.58 22.61 2.5.27 27.69 29.90 :11.97 33.91 35.74 43.78 50.55 56.51 61.91 66.87 71.48 75.82 79.92 87.55 94.57 101.09 107.23 113.03 90 1 a_02 17.00 20.82 24.0.1 26.88 29.•4 31.80 34.00 36.06 38.01 46.55 53.76 GO.10 65.84 71•.I t 7G.02 80.63 84.99 93.11 100.57 107.51 114.03 120.20 Ci 95 12.71 17.97 22.01 25.41 23.41 31.12 3:1.62 35.94 38.12 40.18 49.21 56.82 63.53 69.59 75.17 80.36 85.23 89.84 9 8.4 2 106.30 113.64 120.54 127.06 1:1 100 M.36 18.89 23.14 26.72 29.87 32.72 35.34 37.78 40.08 42.24 51.74 59.74 66.79 73.17 79.03 84.49 89.61 94.46 103.48 111.77 119.48 126.73 133.59 'Calculated from 65.41 X s= 4.Sfi X \`f ' IS (' ' + - +0.06511 .51w Ls - topographic factor 'Z r - 10.000 Vs + I0,000.t i2! I slope length,ft(m x 0.3048) C f - slope steepness. m . esptment dependent upon slope steepness _ (0.2 fnr sopes< I%.0.3 for slopes 1 to 075. _ 0.4 fur slopes 1.5 to 4.5%,and r 0.5 for slopes>5'JL) 7/27/96 Jaeger Engineering page 1 O' Connor Plat Drainage analysis Sediment Pond Stage Storage Table STAGE STORAGE TABLE TRAPEZOIDAL BASIN ID No . 5 Description: Sediment Pond Length: 44 . 00 ft . Width: 32 . 00 ft . Side Slope 1 : 3 Side Slope 3 : 3 Side Slope 2 : 3 Side Slope 4 : 3 Infiltration Rate : 0 . 00 in/hr STAGE <----STORAGE----> STAGE <----STORAGE----> STAGS <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- ------------ 238.00 0.0001 0.0000 239.10 1841 0.0423 240.20 4329 0.0994 241.30 7561 0.1736 238.10 143.09 0.0033 239.20 2039 0.0468 240.30 4591 0.1054 241.40 7895 0.1812 238.20 290.82 0.0067 239.30 2242 0.0515 240.40 4858 0.1115 241.50 8235 0.1891 238.30 443.24 0.0102 2.39.40 2451 0.0563 240.50 51.32 0.1178 241.60 8584 0.1971 238-740"- 600.45 0.0138 239.50 2665 0.0612 240.60 5413 0.1243 241.70 +' 8-939 0.20&2 238.50 762.50 0.0175 239.60 2886 0.0662 240.70 5700 0.1309 241.80 9301 0.2135 238.60 929.47 0.0213 239.70 3111 0.0714 240.80 5993 0.1376 241.90 9671. 0.2220 238.70 1101 0.0253 239.90 3343 0.0767 240.90 6293 0.1445 242.00 10048 0.2307 238.80 1278 0.0293 239.90 3581 0.0822 241.00 6600 0.1515 242.00 10048 0.2307 238.90 1461 0.0335 240.00 3824 0.0878 241.10 6913 0.1587 239.00 1648 0.0378 240.10 4073 0.0935 241.20 7234 0.1661 APPENDIX CHARTS, TABLES, GRAPHS FROM KING COUNTY SWM MANUAL n all op41 ilk .,Wjm 1� ;�,'''�tr � lute _•-� �. - ��� FAN �j\ 31 NOR r� ILI"r� f Op AQ Rolm EWAloss flull I NO a :�►itl► MC �� • KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TABLE 3.5.2B SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A B C 0 Cultivated land(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good Condition: grass cover on 75% or more of the area 68 80 86 90 fair condition: grass cover on 50% to 75% of the area 77 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 Impervious surfaces, pavement, roofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 Single Family Residential (2) Dwelling Unk/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 OU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 impervious portion 3.0 DU/GA 34 of the site or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 OU/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 Planned unit developments. % Impervious condominiums, apartments, must be computed commercial business and Industrial areas. (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering,, Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway n toff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. 3.5.2-3 I/90