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HomeMy WebLinkAbout02958 - Technical Information Report - Drainage ^ ' 4205 148th Ave.N.E.Suite 200 � � CORE Bellevue,Washingfon 98007 425.885J877 Fax 425.8�5?yti3 � DES'G^J ;.�,•' �� ,� . . �- . � S'�OI�1VI I���NA�E AI�A��SIS FOR '� C���I�ESTONE ---���= '�'s y z �VD 4TH �S�REET PLA�A - ' � � ,� -. _ ;.� \J �I' `-" a� ..�_y- 1tE�1TON, WASHL�iGTON �,' , °��'� � -�"�'c�� e�, o,� r �� 1� .M� �'�.�' 3 2 6� � � '�' _ �� �1S'4'ti��0 rV� �DiHA3.��t'� ����!;�9 +.�� Prepared by: Jordan R. Brown, E.I.T. � :�pproved by: Robert H. Stevens, P.E. ,��S ��-�'�-�'� Date: September 2001 Core No.: 00053 � '" .,,f,a, ;<�.v��t','� eJ�� �����v�� , .� "�;, :cy''�•o '�rl�':r �''�� :���/9�� f,�"� ��Z- � � 1 � ��''��� ����J��� Al�l��..����u �OR I ����LES'TONE AND 4� S'�'�E'� PLAZA T�LE O�' �OlV'I'EN'TS I. Proj ect Overview ' II. Off-Site Analysis A. Upstream Analysis B. Downsueam Analysis III. Detention i Water Quality Facility Analysis and Design A. Hydraulic Analysis B. Infiltration Calculations and Overflow Analysis C. Water Quality Volume Calculations D. Facility Design IV. Conve�ance System .�nalysis and Design V. Erosion Control Calculations i I.��2�.TEC'�' O��Y��V: � Fourth and Union Residential is located on the north side of N.E. 4�` Street and is bounded to the east by 100 feet of Union Ave N in Renton, Washington. See attached vicinity map. Two existing buildings currently occupy the 6.31-acre property. The existing ground cover is second growth fir trees and immature alder trees with thick understory. The �ound slopes from east to west at an average slope of approximately 5% across the majority of the property. In addition, some areas of 30% slape e�st in the northern and southern portions of the site where erosion has occurred. The eastern portion of the site, bounded by Union Ave. N., slopes to the east at 2% slope. The developer proposes to construct 18 townhouse and rowhouse buildings in a residential portion of the site, two commercial buildings in a commercial portion of the site, and associated roadway and utilities. The on-site generated runoff for the residential portion will be directed to a water quality/infiltration vault located at the northwest corner of the site. The on-site generated runoff for the commercial portion of the site will be directed to a water quality/infiltrarion vault located at the southwest corner of the site. The stotmwater system has been designed according to the KCSWDM Level Two Flow Control requirements. The overflow runoff will be conveyed through a tight-line system established in the Crown Pointe residential development to the west. A preliminary site plan is attached at the end of this section. The proposed project will address the following as necessary per KCSWDM Table 1.1.2.A, Category 2: Core Requirements 1-8 and the lmown relevant Special Requirements 1-5. Core Requirement #1: Discharge At Natural Location is addressed in Secrion 3 of this report with the installation of an infiltration facility. The infiitration facility will reflect the e�sting drainage pattern or discharge at the e�sting natural location. Drainage currently infiltrates into the existing soils. Core Requirement#2: Offsite Analvsis is addressed in Section 2 of this report. Core Requirement #3: Flow Control is addressed in Section 3 of this report with the installation of an iniiltrationidetenrion vault with an outlet control structure designed per the 1998 KCSW�DM. Biotiltration will not be installed. However, equivalent �vater qualiry wili be provided in the water quality cells. Core Requirement �4: Convevance System will be in secrion N. The civil site improvement plans will show the layout of the conveyance system. Sizing of the system is based on the analysis described in section N. Core Requirement��: Erosion Control is addressed in Section V. Core Requirement #6: Maintenance and Operations Vlanual is not applicable as it will ' be publicly maintained. Core Requiremeat �?: Financial Guarantees and Liabiiitv will be addressed irt the I'i permit application. � Care Requirement#8: VVater Qualitv has been addressed in section III-C of this report. I� Special Requirement #1: Other Adopted Area-Specific Requirements. There are no I�� docurnented requirements specific to this project site, therefore none to address. Special Requirement �2: Flood PlainiFloodway Delineation. The proje�t site is not adjacent to a flood plane or �loodway, therefore no special requirements need to be addressed. Special Requirement �3: Flood Protection Facilities. The project site is not �iose to a flood protection faciliry, therefore no special requirements to be addressed. Special Requirement �: Source Controls. The project site is a multifamily site deveiopment with the associated roadway and utilities. Recommendations to control pollution sources inciude roofing over the dumpster area. Special Requirement �5: Oil Control. The project site is not a high-use commercial site or high-use road intersection, and therefore re�uires no special consideraxion. i � i (�� 3 5 � I �t $`va. 2 SUNS R�� N� N SS�,3v PN � gp � N�� 900 w R� � ,� z ' I � i 2J c' � II � m a z i 8 9 Z 10 � 11 i � � R E N T 0 N S�� I Ne 4n�. sr. 5�� �3R � N , GftE�Nw00o a C�METERY � a ��� 1s9 i 16 15 Z 14 I � �� � � y4 ; �D�R '� E.Y MAPLE'NC00 ` � GO�� CCURS I I�'lCINI TY ��1� N r.s N � �'�G€.� z. sl'I'E �.t�c:�'��d3ie; C�B�L�S'I'aNE A�� 4�S'I'RE�'�' P�AZA �C�� ���.��T �t�. 000r3 a: ROI : Iq: M 00 ;:k>� - �ei�r . �ui�, �c:�c- _ _,.._,,��u. _.. ..., olc i�M,!... 1 REVISED PER CI7Y COMMENTS M S 11.13.01 RHS �++� A'+� ��,�„ 2 NEW COMMERC s�� P� 0,.2.oz-R s �, � ds CITY OF COBBLE'STONE AND 4th S7REET PLAZA "�G. 2001 �.. R'�s ` � RENTON ^�- � � p��:�.� °""'"" planning/Building/Public Wortu Dept. ROAD & STORM DRAINAGE PLAN N0. 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' ..- .e � � , �-- �),�..-�.. �..-. - . ... �,' , _ �". ��� -_�,.__.�---�_�..,_:..�_.� A� m e� . � i�'B..er.lAd ^�,%e���� � . . ...:.:_�.---"'` ___.a3��qNE'�. F'=-.p�.-.. �.a . .���` ' - e � • J _ . " � � � ^ _-�e - ('�° "�"_ - -- � � � - . • � _ ^ . .. „r, ..d . _ _ - �\ / ta • , 7 .. (:n� . ,( ! • R -..._,�. I �� � � � „�'' �` � ,,, � .� t �•�-�� r / n.i n^ I. _. _� .�ql: R�'�'� 11 .�+� Amll- R�trd�� "1b�,�. f�� ,� II �- �"r--1"'�-._.. _,.--~""-'. I. '•..,_,._ .. � �� :II. �3�'�'S�'�'� <��-��.`�SIS: Site visits were conducted during the sprinQ of?001. �. LT�streaffi�nalysis (See attached Upstream Basin Map) Tributary to Site: There is currently a negligible amount of upstream tributary area that is ' northeast of the site. It is assumed due to the high infiltrating soils within the tributary azea that none of the upstream drainage reaches the site. Tributary to Frontage: The storm drain system conveying the runoff from the site frontage and roadway leading from the intersection of NE 4"' St. and Union Ave. N. (about 620 feet)has no upstream system. Upstream Stormwater Svstem The downstream system in Crown Pointe Ap#s., which receives the discharge from this site, has an upstream area of 13.8 acres. However, we have found no problem with the capacity of this system. The information for determining the upstream basin area was extrapolated from the City Utilities Division section maps. The upstream basin area is delineated on a copy of one of the City's Utilities Division secrion maps and attached on the following pa.ges. — —_ ___ _ __ _ . I Pq� 1 \ \l l � �7.0�� � �.. 'd�\ -- _{ ; '•.I �, �,�` I!__N `�`� I 1't1 � f`1J � V 1 i ; � � i � r r•' � i i ;� � ` �o - ~ ���l\� � �W i i. `. 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V I�' < <i, �� . 1�.[Y� � a J , ��z ;,,,_ ,. � - � , _a � ; �� �„ ,-� „�o-. �_ a.ca� 'l- � �-'% i ,aq-� i�.c�.� °. .� � 0 � � I' l� i —'i � ` , i. i d�.re-� . \i t ' �.n e �._ ;��� j %.�, ;� ' {'SITL q` ` ' �` ',,ir �aoe-o' .`., ;�'r ; , .;, ��x � ,L ..) �iti,co-, J - :,-_ - _ + 1� �u�-t , 1 - � '`, /� � ,� � �� � ��•,-�';• = � _ � '� ��� - ►o,c. o � � - � /•- '� i l � �.+'�%:_ ` - _ \ ' ,—_- „f., , << � �. - , r ;,,k ; T� � ,�, -e �u - — � a / %i ,�-i �o - ��' �-ij � 1 , "¢ � �o-. � _ 1 �` f'� G' i�-. f -��� � � a �l'� f� � �` ►�s�-+ � ��f�� � 1 � "'d . �o.��-c ._ n , - , J , .� . � J ,�' �r / � � W � � . _ .E9' �H-?� 17 9-7 " i 9-1 , �._., ` I �,�r:.�..... , / fi /1Nl •119- I�.H9a / IOdq'9 - _ � ��+ - !f I p ,19.' I ' p_"_� ; � r �j a-� i :- n .� v-s . ---u{h� � _ � I '_ � r• �i3a�e-�..� - �, ... ,,,. � ►6.Et-7 1 t-9 � � 1 �� ! 1 ' � � ' 9:12'8 ►-�� � � � � _�Z'' I � � . v i `. ���i i'.\1\ ��.ae- � �'-�./ �.n-s�-v a i l%u-� � �� I � p'�! � b�j � - - + ` .1 � � o.ra � '1 � ! � .��' ��"<'� r�'�:� �5 ' 16 'I'�►3N �5]E � 1��. ' 2._-_ 0 4ao ' � ~ �o ° jJ'�'Y�I'TI�S �Iil�I3Il�� �--� ��n�n c��, �a�. , � ��~eoo �� ' � � =,�► + �'/�✓P�V.T�(:III�ICAL �VI�BS �eo�s I�Is c#.s ae 1,� �s � �� .�o uro�is� �:� ��� � �. � �C2�� �,.�� � 1./� --- - - --- - _.�_____� -- i �. �owmstream�nalysis Resource Review The proposed project is located within the Cedar River Basin. Resources liste�i in the KCStiV�DM were reviewed for existing/potential problems within the study area. The study area is that area associated with the upstream drainage system that is tributary to the point of connection of the proposed onsite drainage system to the NE 3'� Street drainage system and downstream along NE 3'�Street `,i4-mile from the subject site. FENIA Maps: FEMA map dated may 16, 1995 numbered �3033C0981F was reviewed. There are no flood areas within the study area. 5ensitive Areas Folio: The December 1990 Sensitive Areas Nlap Foiio was reviewed to confi�n whether or not the study area is located within a wetland, stream or flood hazard area, erosion hazard area,landslide hazard area, seismic hazard area, or caal mine hazard area There are no wetlands, streams or flood hazard areas, erosion hazard areas, landslide hazard areas, seismic hazard areas, or coal mine hazard areas within the study area. Drainage Complaints: Per the �'iri� of Re:�tan, there ar� r�o reported ::omplaints ti�ithin the stlidv area. King County Soils Survev: The soils on site consist of _�ldenvood, aravelly loam matenal (=�g�';. Soiis within %4-mile downstream are Arents, Everett material (�n). So�l: upstream and tributary to the 12" storm drainage li�e aiona ���: �='� ���r�,�, �� � .�_� � ,-��� � � ; ; `Ir E e� r` . . � ; �: Downstream Drainage Route Proposed development of the site-will include connection of a proposed overflow system for each infiltration vault to discharge into the existing Crown Pointe Apts. � stormwater system. Design required the modeling of the existing stormwater system in Crown Pointe in order to establish the capacity of the system. The objective of modeling the Crown Pointe stormwater system is to verify that the system can accommodate the overflow from the 4`'' & Union infiltration system for the 100-yr, 24-hr storm event. The existing system includes an infiltration pipe series system. The system is described in as-built plans per the City of Renton. The 100-year, 24-hour storm runoff capacity was found through an iterative process of level-pool-routing with Water Works software utilizing SBUH methodology. Several possible infiltration rates have been analyzed. The design infiltration rate for the system is recalled to be 30 inches/hr according to Ed Jones, P.E., formerly of DEI. VIr. Jones recalls the use of the 1979 King County Surface Water Design Manual, using the Y&W Nlethod. The storm report documenting the analysis is unavailable. Soil tests were taken at the test site and the infiltration test concluded that the infiltration capacity of the soil was over 2-in per minute. The current design standard at the time was a maYimum of 2-in per minute or 30" per hour. The system was designed to infiltrate at that rate with no safety or service factor. The Crown Pointe stormwater system has been modeled assuming type A soils— as were used at the time of the system design. This has been done to achieve the design flow rates. The 100-yr, 24-hr design storm event is 3.90 inches precipitation, the 25-yr is 3.40 inches. Setting up the pre-developed condition, we used 7.04 AC forested pervious, with a curve number of 55. Setting up the developed condition, we used 2.86 AC pervious grass, with a curve number of 68; and 4.17 AC of impervious surface, with a curve number of 98 (per WSDOE manual). The storage structure was ! modeled with a stage-storage table that represents the series of detention pipes. The control orifices combined a fixed stage-discharge (representing fixed rate of infiltration regardless of stage) with the design storm runoff for 4`'' & Union representing the base-flow. The results of hydrograph analysis of the existing flows from the Crown Pointe development for the 100-yr storm indicate a peak flow of 4.42 CFS. The flow rates from the Cobblestone development for the 100-yr storm are 1.40 CFS far the residential vault, and 0.5? CFS for the commercial vault, for a total of 1.97 CFS of ' 100-yr overflow. Therefore, the necessary total flow capacity of the Crown Pointe I system is 6.39 C�S. , The results of the modeling iteration indicate a capacity of 6.�2 CFS is established with an infiltration of 23 inches per hour. This is more ihan the anticipated inflow of 6.39 CFS. _ During a 25-yr storm, the system would not receive any flows from the proposed project and would therefore not have any impact with which tfl be concemed. The Water Wor�s methodology is provided here and evidence is included on the following pages. We modeled the system using various infiltration rates to demonstrate feasibility for actual soil conditions. For each iteration, the stage-discharge relationship was modified to reflect the flow rate infiltrated, based on the area of the infiltration trench around the infiltrarion pipes per city of Renton as-built plans. In addition, the basin parameters included a base-flow that coinpensated for the infiltration in order to meet maximum capacity. This was done until the maximum water surface met the riser elevation in the control structure (el. 3�5.66). The hydraulic,�l�ydrologic model has established a maximum inflow of 4.42 CFS from the Crown Pointe stormwater system for the 100-yr-storm design flow, �,vith 3.32 CFS peak outflow according to the level pool routing tabie. Assuming an additional baseflow of 2.0 cfs need be accominodated by the downstream system, an infiltration rate of 2�",�'hr is necessary. This is less than the 30"�hr in the ori�inal desi�n. Therefore, the requirement to provide discharQe for the 100-yr, 24-hr storm event is satisfied. The hydrologic e?esign software output is included at the end of this section. . The system downstream of the Crown Pointe system has shown to be of sufficient capacity to accommodate the additional flow. As-built information for the 1984 u, Street Improvement Project along N.E. 4 Street and Monroe Avenue N.E. shows that a 36" storm drainage system was installed and channeled to an infiltration pipe near the City of Renton Public Works yard. This system has an overtlow route that conrinues down N.E. 4`''in a 12"pipe. The site includes an area of pavement along Union _�ve. �. that will 5heet-tlo��• into the western tlow line of the arterial. This 4,640 SF of PGIS is less than the 5,000 SF that would require water quality treatment. The tributary area will �enerate 0.054 CFS for the 10-yr, 24-hr design storm that will be channeled north along the flow line until being received by the type 1 catch basin about 260 feet north. The CB's invert is the highest elevation of the tight-line conveyance systerri that runs east, across the Union Ave. N.E. The system then serves a shoppin�,� center, then continues south across �V.E. =�`'' St. to discharQe into a natural stream channel. 1/10/02 2 : 59 : 42 pm Dodds Engineers, Incorporated page 8 Cobblestone/4th St . Plaza 00053 Crown Pointe Apts . SW Modeling --------------------------------------------------------------------- --------------------------------------------------------------------- LEVEL POOL TABLE SUMMARY AIATCH Itv'f'IAW -STO- -DZS- <-PEAK-> OtiTSLOW S�ORAGE <------DESCRIPTION-------> (Cfs) (cfs) -id- --id- <-STAGE> id (cfs; VOL !cf) Dev. Storm 100yr .. .......... . 0.00 4.42 comnosit combi30 350.19 7 3.32 1170.72 cf Dev. :OOy 30+2.0 cfs ......... 0.00 6.42 comaosit combi30 352.28 8 3.37 6549.59 cf Dev. ;OOy 25t2.0 cfs ......... p.00 6.42 composit combi25 354.94 9 2.91 13644.67 cf Dev. 100y 20+2.0 cfs ......... p.00 6.a2 composit combi20 356.0: 10 6.42 15042.55 cf Dev. 100y 22+2.0 cfs ......... 0.00 6.42 composit combi22 355.82 11 3_69 14878.34 cf Dev. 100y 23+2.0 cfs .. ..... . . 0.00 6.42 c�mposit combi23 355.72 12 3_10 i4793.21 cf �� � , ,� ,�.� ��,,�, ���`�,� ��` �3,.> 1/10/02 2 : 56 : 30 pm Dodds Engir.eers, Ir_corporated page 2 � Cobblestone/4th St . Plaza 00053 Crown Pointe Apts . SW Modeling --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY _ BASIN ID: cpD1B20 NAME : C Pt . Dev. 100yr I20 Base 2 . 00 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7. 03 Acres BASEFLOWS : 2 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 2 . 86 Acres 4 . 17 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 68 . 00 98 . 00 TC. . . . : 16 . 35 min 6 . 36 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 200 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0400 impTcReach - Shallow L: 150 . 50 ks :27 . 00 s : 0 . 0050 impTcReach - Channel L: 450 . 00 kc : 21 . 00 s : 0 . 0050 PEAK RATE : 6 .42 cfs VOL: 9 . 81 Ac-ft TIME : 480 min �� .�' ___.____..._�►s'� ;;`��'�� BASIN ID : cpD1B22 NAME: C Pt . Dev. 100yr,��Base 2 cfs � SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 . 03 Acres BASEFLOWS : 2 . 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 2 . 86 Acres 4 . 17 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 68 . 00 98 . 00 TC. . . . . 16 . 35 min 6 . 36 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 200 . 00 ns : d . 1500 p2yr: 2 . 00 s : 0 . 0400 impTcReach - Shallow L: 150 . 50 ks : 27 . 00 s : 0 . 0050 impTcReach - Channel L: 450 . 00 kc : 21 . 00 s : 0 . Od50 PEAK RATE : 6 .42 cfs VOL: 9 . 81 Ac-ft TIME : 480 min � ��' � ___ - -�� �t�`� BASIN ID: cpD1B23 NAME : C Pt . Dev. 100yr !2�)Base 2 cfs � SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 . 03 Acres BASEFLOWS : 2 . 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 2 . 86 Acres 4 . 17 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 68 . 00 98 . 00 TC. . . . . 16 . 35 min 6 . 36 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 200 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0400 impTcReach - Shallow L: 150 . 50 ks :27 . 00 s : 0 . 0050 impTcReach - Channel L: 450 . 00 kc :21 . 00 s : 0 . 0050 PEAK RATE : 6 .42 cfs VOL: 9 . 81 Ac-ft TIME : 480 min 1/10/C2 2 : 56 : 30 �m Dodds Engineers, Incorporated p�ge 5 Cobblestone/4th St . Plaza 00053 Crown Po;�r_�e A�ts . SW Modeling S'�';RAGE STRUCTLI�E LIST UNDERGROUND PIPE ID No. CPt . P60 �escription: Crown Point Det . Pipe 60" �iameter: 5 . 00 ft . Length: 385 . 00 ft . Slope . . . : O . 0039 ft/ft upstr : dnstr: UNDERGROUND PIPE ID No. CPt . P72 Description: Crown Point Det . Pipe 72 " Diameter: 6 . 00 ft . Length: 260 . 00 ft . Slope . . . : - 0 . 0052 ft/ft upstr: dnstr: � TRAPEZC�DAL BASIN ID No. Npond Description: infiltration Pond North site Length: 50 . 00 ft . Width: 30 . 00 ft . Side Slope 1 : 3 Side Slope 3 : 3 Side Slope 2 : 3 Side Slope 4 : 3 Infiltration Rate : 0 . 00 min/_nch TRAPEZOIDAL BASIN ID No. Nwetpond Description: wet Pond North site �ength: 6 . 00 ft . Width: 20 . 00 ft . Side Slope 1 : 2 Side Slope 3 : 2 Side Slope 2 : 2 Side Slope 4 : 2 Infiltration Rate : 0 . 00 min/inch STORAGE LIST ID No. composit Description: composite of 60" and 72 " � 1/10/02 2 : 56 :31 pm �odds Engirleers , Incor�crGted page 6 Cobblestone/�th St . Plaza 00053 Crown Pointe Apts . SW Modelir_g DISCHARGE- STRUCTURE LIST COMBINATION DISCN.ARGE ID No. combil� Description: infi115 and orifice Structure : control Structure : Structure : infl5 Structure : Structure : riser COMBINATION DISCHARGE ID No . combi2U Description: infi120 and orifice Structure : control Structure : Structure : inf20 Structure : Structure : riser COMBINATION DISCHARGE ID No . combi22 Description: infill5 and orifice Structure : control Structure : Structure : inf22 Structure : Structure : riser COMBINATION DISCHARGE LD No. combi23 Description: infill5 and orifice Structure : control Structure : Structure : inf23 Structure : Structure : riser COMBINATION DISCHARGE ID No. combi25 Description: infill5 and orifice Structure : control Structure : Structure: inf25 Struc�ure : Structure : riser COMBINATION DISCHA�GE ID No. ccmbi30 Description : infi130 and orifice Structure : control Structure : Structure : inf30 Structure : Structure : riser COMBINATION DISCHARGE ID No . com�i7 . � Description: infil 7 . 5 and orifice Structure : control Structure : Structure : inf7 . � S�ruct��:�e : ctruct�.�re : �-iser i 1/10/02 2 : 56 : 31 pm Dodds Engineers, Incorporated page 7 Cobblestone/4th St . Plaza 00053 Crown Pointe Apts . SW ModelinG DISC?iARG� S"'R�C'�'JR� LIST CCM�IIvA'�'�ON DISC��RGE ID No . ccrri�i8 Description: infil 8 . 0 and orifice Structure : control Struct�are : Structure : inf 8 St-�.�c�..ure : Structure : riser MULTIPLE ORIFICE ID No. control Description: CB 4A Outlet Elev: 348 . 10 Elev: 348 . 10 ft Orifice Diameter: 1 . 7500 in. Elev: 353 . 82 ft Orifice 2 Diameter: 2 . 1750 in. Elev: 357 . 80 ft Orifice 3 Diameter: 0 . 0000 in. DISCHARGE LIST ID No. inf15 Description: Infiltration 15in/hr DISCI�iARGE LIST ID No. inf20 Description: Infiltratior. 20in/hr DISCHARGE LIST ID Nc. inf22 Description: In:�ltration 22ir_/hr DISCHARGE LIST I� No. inf23 Description: Ir_fi�tration 23in/hr DISCFARGE LIST ?D Vo. inf25 Descript�cr_: I�f�ltra�icr_ 25in;rr DISCHARGE LIST ID No. int3C Description: Infiltration 30in/hr DISCHAR.GE LIST ID No. inf7 . 5 Description: Infiltrat�on: 7 . 5 i�j_ �TSC_��cG� LIS�' �n �Io. �nf� Description: Infiltration: 8 in/hr RISER DISCHARGE ID No. riser Description: 18" cmp cross Riser Diameter (in) : 18 . 00 elev: 355 . 66 ft Weir Coefficient . . . : 9 . 739 height : 357 . 00 ft Orif Coefficient . . . : 3 . 782 increm: 0 . 10 ft ��. ����.�;��o�v i�v����Q�a�,��r� ���c�.�� ��r�.�s�s & ��s���r: �. �ydraulic Analysis The drainage analysis for the project site was modeled according to the KCSWDM, Level 2 Flow Control criteria. The project storm system design ' calculations and considerations are presented in this section. The soils on site consist of Alderwood, gravelly loam ma#erial (AgC) according to the King �ounty Soil Survey. See Section 2 of this report. According to the soil type, the site will be considered to have pervious soils e�iibiting characteristics of Type C soils. i EXISTING CONDITIONS ' The property is currently vacant. The existing ground cover is second growth evergreen and immature deciduous trees with dense undergrowth. The specifics of the hydrologic soflware input data are given in subsection D of this section. DEVELOPED CONDITIONS The developer proposes to construct 18 townhouse and rowhouse buildings in a residential portion of the site, two commercial buildings in a commercial porrion of the site, and associated roadway and utiliries. The residential and commercial portions of the site aze treated as separate basins and both have a separate water quality%infiltration/detenrion vault. The impervious and pervious areas were measured by ACADD software. The pervious portion of the site was assumed to be lawn and landscaping, good condition. The specifics of the hydrologic design parameters are given subsection D of this secrion. �. Infiltration Calculations and �verflow�nalysis The on-site generated runoff for the residential portion of the site will be directed to a thre�-celled water qualityiinhltrationidetention vault located at the northwest comer of the site. Runoff for the commercial portion will be directed to a four-celled water quality/infiltrationidetention vault located at the southwest corner of the site. Infiltration within the water quality/infiltrarion vaults will be used for mitigation of the stormwater discharge to meet Core Requirement #3 of the 1998 King County Surface Water Design Manual. The vaults are sized with KCRTS soflware to match the developed with the pre-developed flow durarions. The KCRTS saftware allows the design of the infiltration vault as an infiltration pond with vertical side slopes and impervious sides. The geotechnical firm Earth Consultants has supplied the infiltration rate based on soil tests at the location and elevation of the bottom of the future infiltration vault sites. The infiltration rate at the site of the vault in the residential portion of the site, Cobblestone, is 13.76" per hour. The infiltration rate at the site of the vault in the commercial portion of the site, 4`� Street Plaza, is 2.75" per hour. Soil test recommendations are included at the end of this section. The geotechnical engineer used the EPA falling head percolation test procedure and applied a safety factor of 0.3 to the test results. The KCSWDNI provides the use of iniiltration rate correction factors to best estimate the long-term performance of the infiltration system. The correction factors are used in the following equation found in KCSWDM 5.4.1: I desi�— I measuted X F �y��X F g���, X F p�u�g (5-9) I ��„�a=45.8b for the north, and 9.16 for the south F �Sti�=0.30 for the EPA Falling head test. F �eO��=4 D/W+.OS (between 0.25 and 1.0) =1.0, since the depth of the facility bottom is at least 5 feet above the maximum wet season water table or the nearest impervious layer (per Rod Palacios of Earth Consultants Inc.) the factor reduces to the maximum value of one. F pi„�„g= 1.0 when preceded by a water quality facility Therefore the design rate is that supplied to us from the geotechnical engineer. The systems have been designed to accommodate peak flows up to the 100-yr, 24-hr storm event. An emergency overflow route will divert water toward the east, along curb and gutter in Crown Pointe, to then be received by downstream catchbasins. C. Water Quality Volume Calculations_ The water quality cell in the water quality/infiltration/detention vault will be used for water quality treatment of the stormwater to meet Special Requirement #5 of the 1998 King County Surface Water Design :�Ianual. The bottom of the ceil will be impervious, sloped, and allow for sediment accumulation. A biofiltration swale will not be installed per Core Requirement ,#3 as allowed by the City of Renton. According to the 1998 King County Surface Water Design Manual, the required volume for the pre-settling cell in the vault shall be equal to 0.75 times the runo�from the mean annual storm, V�per figure 6.4.1.A and secrion 5.4.1 KCSWDM. However. a wet-vault cell will satisfy the basic water quality requirement and the pre-settlin�,� requirement. The following equarion provides the required volume: Wet Vault Volume: Ve f�`Vn where f is the volume factor of� { 3*[(0.9*A; SF-�.?�*_�., SF) *R"'1�� CF } (per section 6.�.1_1.1 Where: ��is the area ut impervious suriace in square t�ect A�is the area of till grass surface in square feet. R is the rainfall (in inches) for the mean annual nifio�f��to������. from Figure �.�.1..-�. The north pre-settling vault requires v��lume: 3*[(0.9*139,827 SF+0.25*60,548)*U.4i";�1�]=16,�6� CF � YieldinQ one 17.5' x 64' x 8.24' {ave.) cell, and one 1�.�' s b=�' � �.6�'' I ave.1 cell. T'he �outh pre-�ettlin�,z �ault requires ��olume: 3*[(0.9*57,194 SF=0.25*16,857)*0.47"�`l�J=b.��� CF � � Yieldina two 13' x 46' x 6.9' cells. The �,�aults w�ill be built 3ccurdin�� to ILCS��'D�1 6.-�.�.= with a wall tu divicie the ��ault into two cells. The bottom will have 5% slope from the sides to the center. Additional storage will be provided to allow �ediment accumulation to �ne foot above the bottom elevation of the tirst cell. D. Facility Design KCRTS DESIGN FACTORS: tiorth conditions: Infiltration rate: 13.76"/hr, or 436 min./inch Pre-developed cover: 4.6 AC till forest Developed cover: 3.21 AC impervious and 139 AC till grass South Conditions: Infiltration rate: 2.75";'hr, or 21.8 min./inch Pre-developed cover: 1.77 AC till forest Developed cover: 1.313 AC impervious and 0.387 AC till grass Runoff Files interpolation value is 1 for the SeaTac runoff files. Frogram output including final design dimensions is attached. The vaults have been desi�ed per KCRTS to contain storms up to the 100-yr, ?4-'.nr design storm. Based on the outlet to the overflow system, the live storage elevation meets the overflow invert elevation. The bottom of the vault is lower to achieve the desired infiltrative soils and corresponding infiltration rates. The final vault specifications for each basin are summarized as follows: • North vault (00053rvlt.rd fl Max. Water Surface Elevation: 385.0 Bottom Live Storage Elevation: 375.0 Vault Bottom Elevation: 367.0 Required Live Storage Volume: 12,266CF DesiQned Live Storage Volume: 12,266 CF Vau1t Dimensions: 1?.� x 5�' Y 1�.98' a South vault (00053cvlt.rdfl �1ax. Water Surface Elevation: 393.0 Bottom Live Storage Elevation: 387.0 Vault Bottom Elevation: 383.5 Required Live Storage Volume: 9,016 CE Desi�ed Live Storage Volume: 9;016 CF �'ault Dimensions: ?8' x 46' x " � �acili� �iz�g. F1ow Dura�;ion Cu�ve �it Project: 00053 Col�i��estone/F'ourth Stn-e�t Plaza Residential Site Infiltra.tion/Detention Vault The infiltraUon rate �s reduced in order to model the reduced infiltration area. The infiltration rate is adjusted proportional to the percentage of infiltrarion azea to the total area of the vault layout. The adjustment factor is refined though iteration. Final design will aciueve the volume required. 17.5'x54'=945 SF,Footing area=(2*X*1'+2*(54-4 )*(1'�X*2') ,X=17.�',FA=170 SF Actual infiltration rate= 13.76 in.:l�r. or 436 min.;in. Adjusted infiltration rate: (945 SF— 170 SF)/945 SF=0.820 of actual, 18.0%reduction. ' Adjustment yieids an infiltration rate of 11.28in.�'hr or 532 miniinch Final Vault size: 17.5'x 54' File: 00053rvltxdf By� � . : -. � : . • . - °- � _ __ _ N O IJLi��;�I`'�l�i�:LI��.��::r "-� ��� � �—.y_ �OCf;..�i�l'�_�2.d'�r ♦ � I� � � i � � ,••,����-�� �� ��-_ � o iF`< �I �:i�--, I � � ��. LL � I Up _,�, � �� ,4 I � � ��# — i � � �. � � + ...,� I � N �^�� � � � -# --- — ---------- � � ,.;..� � M1� I O � I �--- O � : i �d' O O O � �'�^--«. 1 I � � 10 �5 10 �d 10 J 10 ` ,�� Probability Exceedence �dsra�I' ���� '-� ���i ��;�` _���,�:: �-r�. ���._ 9=�=- ���,.- _�_ ��.��;a.�,�:�s � 00a5�Rv1[Single celled vault Durauon C;uve i)9/10i01 �c�_�n»��i�e�e%t�.... _ac�_it�i Type o= r�cility: Infil�raLion _ond Side S�cDe: 0.00 H: 1'I Pond Bottom Ler.gth: 54.00 f_ Pond Bottom Width: _7.50 f� Por_d Bottom �ea: 9a5. scr. L� Top Area at 1 ft. PB: 94�. sq. f� 0. 022 acres �ffecti-re Storage Dep�h: ?2. 98 ft Stage 0 Elevat_on: 367.00 t� Storage Vol�.une: 12256. cu. �� 0.282 ac-ft Ve=_ical Permeab�lity: 5.30 m�^/'_r_ Pe`-meable Surfaces: Bottom Riser Head: 12. 98 ft R�ser Diamecer: 12.00 incres Number of orifices: 1 Fu_1 Heac _ - Orif�.ce # Height DiGmecer D_scnarge Diame��� (ft) l-rj (��5; ;in) 1 0.00 =. :� 0 . 2�s To� Nctcn wei=: Nor_e ��Lt=1�.� Ra_-rc �ur-r�: Ncr_e ;r..'�? �__IG.._ ..__ v_,._GC.c.. ✓1._�.:'1:'�y"' iE'_"�v_..__vr .�..11_ .__�Q (=ti I,ft; (cu. =t) (ac-ft) icfs) (cfsj (sq. tt; C.00 367 .�0 0. 0.000 O.OGO 0.00 945 . a.02 367 .�2 19. 0.000 0.010 0.25 9a� . 0.03 36? .03 28. 0.001 0.014 0.25 945 . I 0.05 36i .05 4?. O.00i O.C�7 0.25 945 . 0.07 367.0' S6. 0.002 O.C;9 0.25 94� . 0.09 367.09 85. 0.002 O.C22 0.25 94� . 0.10 367.�G 95. 0.002 O. C24 0.25 945 . 0.12 36,.12 113. 0.003 0.026 0.25 94�. � 0.14 367. 14 132. 0.003 0.02? 0.2� 94� . 0.33 367 .33 3_2. 0.007 0.043 0.25 94� . 0.�2 367.52 491. 0.011 0.054 0.2� 94� . 0.72 367.72 680. O.G16 0.063 0.25 945 . 0.91 367. 91 860. C.020 0.071 0.25 94�. 1.11 368 .11 i049. 0 .024 0.078 0.25 94�. 1.30 368 .3C 1229. 0 .028 0.084 0.25 945. 1.�9 368 . 49 1408. 0.032 0.09C 0.25 945 . 1. 69 368.69 1597. 0.037 0.096 0.2� 94.; . 1.88 368.88 177;. 0.041 0.1�1 0.2� 94� . 2.07 369.C7 i9�o'. G.Q45 0.�06 0.25 945 . 2.27 369.27 21c�. O.G49 C.11' G.25 945. I� 2.46 369.40 2325. 0.0�3 C.li6 0.25 94�. I� 2.60 369. 56 2514. 0.0�8 C.12C 0.25 995 . 2.85 369.�5 2693. 0 .062 0. 125 0.25 945 . 3.04 ?70.04 2873. 0.066 0. 129 0.25 94� . 3.24 370.24 3062. 0.070 0. 133 0.25 94� . 3.93 3'0.43 324_. O.Oi4 0.�37 0.25 945 . , 3. 0� 3�O. c� _�'_�_. �. G�9 0 . _�= G.25 ��5 . � ^ . . . ^.� - I��� �. �2 ���.82 35_G. ,, .C8� u.l �-� 0.�� 9�,, . =� . 01 371.0= 3790. �.C87 O.la8 0.25 94�. a .21 37�.21 39?9. 0.091 C.151 0.25 9a5 . 1 .4C 37i.40 415� . Q.095 0.=55 _ 0.25 945. s .�9 371.59 4338. 0.100 0.158 0.25 945. 1 .,9 3;1.79 a_527. �.1�4 0.162 0.25 94�. � . 98 3?1.98 a706. �.108 C. 165 0.25 945. 5 . 17 372.1? 4886. 0.112 C.168 0.25 94� . � .37 372.37 5075 . 0.116 0._71 0.25 995. � .56 372.56 5254. 0.121 0.:?4 •�.25 94�. 5.75 372.76 5443. 0.125 0.177 0.2� 945. �. 95 372.9� 5623. �.?29 6.180 0.25 945. 6.14 373.14 �802. C.133 C.183 0.25 945. 6.?4 373.34 5951. 0.138 0.186 Q.25 9a5. 0'.53 373.53 6171. 0. 142 0.1�9 �.25 945. ,.�2 373.72 635�. 0.140' 0.19= 0 .25 945. ' c. a2 3?3.92 6539. O.i50 0.194 0.25 945. - .11 374.11 67_9. 0.154 0.197 0.25 9a5. � . 3' 37�.31 6908. 0.1�9 0.2C0 0.25 955. ? .50 374.50 i088. 0.153 0.202 C.25 945. , . 09 3?4.69 7257. 0.157 0.205 0 .25 945. , .39 374.89 745E. 0.171 0.207 0 .25 94�. 3 .08 375.08 ?636. 0.?75 0.2i0 0.25 945. � .�7 375.�7 78=5. O.i79 0.2=2 0:25 945. � .47 375.47 8004 . O.I84 0.215 0.25 945. 8 . �0 37�. 66 8184 . 0.188 0.217 0.25 945. 8 . 86 37�.86 �3i3. 0.192 0.220 0.25 94�. ;.�� 375.05 �552. 0.196 0.222 0.25 94�. 3.24 375.24 8732. 0.200 0.225 0.25 945. ?.?4 376.�4 8921. 0.205 0.227 0.25 945. a . 63 376. 63 9?00. 0.209 0.229 0.2� 945. 7. 82 370.�2 9�80. 0.213 0.231 0.2� 545. =,� . ?2 377.02 9469. 0.217 0.234 0.25 945. =�.21 377.21 5648. 0.221 0.236 0.25 94�. =0.41 3?7.41 9837. 0.226 0.238 G.25 94�. ?0.60 377.60 lOqi7 . 0.230 0.240 0.25 945. 10.75 3%7.79 10197. 0.234 0.243 0.25 945. 10.99 377. 99 ?0386. 0.238 0.245 Q.25 945. 1_.18 378. 18 10505. 0.243 0.247 C .25 945. _�.37 378.?7 =0745. 0.247 G.249 ^u.25 945. =1.57 378.57 �0934 . 0.251 0.251 0.25 94�. =1.76 378.76 11113. 0.255 C.253 0.25 945. =1. 96 378.96 11302. 0.259 0.25� 0.25 945. _2.15 3�9. 15 11482. G.264 0.257 0.25 945. �2.39 379.34 11661. 0.2c8 C.259 0.25 945. '_2.�4 379.54 1_c�0. G.272 C.261 �.25 545. _2.73 379.73 i2G30. 0.276 C.263 0.25 9��. =2.92 3?9. 92 =2209. 0.280 0_.26� 0.25 9�5. =2. 98 375.98 12266. 0.282 ''�.0.26> 0.25 94�. '�3.08 380.08 12361. C.284 0.575 0.25 945. 13.18 380.18 12455. � .286 ?.1a0 0.25 945. '_3.28 380.28 12550. C.288 1.8'0 0.25 945. �3.38 380.38 126q�. 0.290 2. 660 0.25 945. _�.48 380.48 �2739. 0.292 2. 950 0.25 9a5. _�.58 380.58 _28�3. 0.295 3.200 0.25 945 . , i3 . 68 380. 08 i2928 . 0.297 3_440 0.25 945 . 13 .?8 38C.?w ���ZL . O.�GQ 3. 5c0 Oa25 9�5 . =� . 3N ��� . �8 ���i . J. ��= �. � ��J �G.�� yu� , _3 . 98 380. 98 1321�. 0.303 a .060 0.25 94� . _? .08 38�.08 '_3306. 0.305 4 .24G 0.25 5�� . �1 .18 38=. 18 ,�3�00. Q.3G8 4.42C = 0.25 9��. 11 .25 381.28 13495. 0.310 4 .590 0.25 945 . �? .38 381.38 13589. 0.312 4.750 0.25 945 . "_4 .48 381.48 =3684. 0.314 4 . 910 0.25 y4� : =? .58 381.58 =37?�. 0.316 5.070 0.25 94� . _� .68 38_. 68 =387�. 0.318 �.21G 0.25 9a_�. �4.78 38=.i8 1�967. 0.321 5.360 C.25 9�5 . �1.88 381.88 14Co2. 0.323 5.500 � .25 9a5 . �3yd In�low Outflow Peak StoYage Target Calc Stage E_ev (CL-Ft) (�c-=t) : =.81 ******* 1.4C 13.22 380 .22 12489. 0.2�7 � 0.91 0.29 0.25 1i.09 378.09 10481. C.241 3 0.96 **�**** 0.26 12.63 379. 63 11939. 0.274 1 0.90 **�**** 0.25 1i.15 37E.15 1054i. 0.242 . � 1.08 *x**�** 0.23 9.36 376.36 8841. 0.203 6 0.99 *�**�** O.i9 6.43 3?3.43 6G77 . 0.14� 0.?5 ******* 0.12 2.65 369. 55 2504. 0.05? 8 0.83 ******x C. 12 2.5a 359.54 240�. � .055 ---------------------------------- �cute "i_ne Ser_es through Facili�f <�=1ow Time Series =i'_e:00053r.dev.ts` CLt==ow Time Series Fi�e:00053rv1trdout I�f_ow/Cut��ow Ar.alys'_s , Peas =atlow Discha_ge: =. 8�_ CFJ a� 6:00 cr. Jan 9 _n Year 8 �, ��ak Cutflow Discrarge: '.40 CFS a� 8 : 00 cn �an 9 _^ Year 8 ! Peak Reservoir Stage: �3.22 Ft Peak Resernoir �lev: 380.22 �'t :?3k �cS2'_'7C�_ �tc=ace. 1?489. .,�-,t . J.GS __�-_.. =1�w Gur�tion =_om ,ime �2r_�s �i1e:u0C�53rv�trccu�.rs� �u-�o=z Coun� Frequer,cy CDF Exceedence_Prcbability ��'S � $ % �.00� 58759 95.824 95.824 4.i?6 0.41�E-Ol �.Oil IEI9 2. 54� 98.464 1.536 G.154E-01 ���.018 142 0.232 98.69� 1.305 Q.130E-01 ��.020 63 �.103 98 .?9� 1.202 Q. 120E-01 �.033 79 0.129 98.927 1.073 0. 107E-C1 �.04G 6� 0.106 �°.�33 0. 96? �.967E-02 O.C48 53 0.086 �9.1=9 0.881 0.88iE-02 �.055 59 0.096 99.2=6 0.784 0.784E-02 �.063 49 0.080 99.296 0. 7G5 0.705�-02 �.070 30 0.045 99.34� 0. 650 0.656E-02 ��.0;? 49 0.080 99.424 0.576 0.576E-02 C.085 �9 O.G64 99.488 C.5=2 0.5;2E-G2 0 .092 3� �.0�'? 99.54� 0.4�5 0.45�E-02 0 .099 30 0.049 99.594 0.906 v.406E-02 0. 107 34 0.055 99.649 0.35i 0.35 L-02 �. 1�4 31 0.05_ 99.700 0.300 0.30u^_-02 J . 1%1 �� 0.030 :9.��6 0.26� 0.264=-02 . -''�' ' 1 '� ��_«_�� • 0. 129 17 0.029 99.764 0.236 0.236E-02 0. 136 14 0.02.s 99.i86 0.214 0.2?4r.-02 ' 0. 143 14 O.C23 99.8G9 0.191 0.�91�-a2 O. i51 :� 0.029 99.�39 =0.101 O.i�l�.-02 ' 0. 158 :1 0.018 99.E56 0. 194 0. 144E-02 0. 165 11 0.0�8 99.874 0.126 0.126E-d2 ' �. =73 8 0.013 99.88? 0.113 0.1'3E-02 0. �80 8 0.013 99.901 G.099 0. 995E-03 0. 137 8 0.013 99.914 C.086 0.864_-03 , 0. 195 � 0.013 99.927 0. �73 0.734_-03 0.202 2 0.003 99. 930 0.070 0.701E-03 0.210 6 0.0,� 99. 940 0.060 0. 603E-03 ' C. 217 1 0.002 99. 9�1 0.059 0.587E-�J3 � C.22Q 14 0.023 99.964 G.036 0.359E-03 0.232 3 0.005 99.969 C.031 0.310E-03 0.239 4 O.G07 99.976 O.Q24 0.245E-03 0.296 8 O. C13 99.989 �.0�1 0. 114E-C3 I 0.254 4 O.J07 99.995 �.005 0.489E-C4 C.26i 1 C.002 99.99i 0.003 0.326E-04 � i I � OOG53nex r low Fre�sency Ar_a'�ysis `;'ime Series File: 00053nex.tsf Froject Location:Sea-Tac � ---Annual Peak Flow Rates--- - ----Flow Frequency Analysis------ rlow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) {CFS) Period -- 0 . 290 2 2/09/01 18 : 00 0 . 371 1 100 . 00 0 . 99 0 Q . 079 7 1/Q6/02 3 : 00 0 . 290 2 25 . 40 0 . 96 0 0 .215 4 2/28/03 3 : 00 0 . 223 3 10 . 00 0 . 90 0 0 . 008 8 3/24/04 20 : 00 0 . 215 4 5 . 00 0 . 80 0 0 . 128 6 1/05/05 8 : 00 0 . 188 5 3 . 00 0 . 66 7 0.223 3 1/18/06 21: 00 0 . 128 6 2 . Q0 0 . 50 0 0 . 188 5 11/24/06 4 : Q0 Oa079 7 1 . 30 0 . 23 � 0 .371 1 1/09/08 9: 00 0 . 008 8 1 . 10 O . Q9 1 Computed Peaks 0 . 344 50 . 00 0 . 98 a Fage 1 00053nde�r �low Fr�quency Ar�a�ysis '�ime Series File: 00053ndev.tsf � Project Location:Sea-Tac I ---Asinual Peak Flow Rates--- -- ---Flow Frequency Ar�.alys=s------ Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prcb �' (CFS) (CFS) Period 0 . 902 6 2/09/O1 2 : 00 1 . 81 1 100 . 00 0 , 99 0 0 . 748 8 1/05/02 16: 00 1 . 20 2 25 . 00 0 . 96 0 1. 08 3 2/27/03 7 : 00 1. 08 3 I0 . 00 0 . 90 0 0 . 825 7 8/26/04 2: 00 0 . 99a 4 5 . Q0 0 . 80 ' 0 0 . 990 4 10/28/04 16 : 00 0 . 959 5 3 . 00 0 . 66 7 0 . 959 5 1/18/06 16: 00 0 . 902 6 2 . 00 0 . 50 0 1 . 20 2 10/26/06 0 : 00 0 . 825 7 1 . 30 0 . 23 1 ' 1. 81 1 1/09/OS 6: 00 0 . 748 8 1 . 10 0 . 09 1 Computed Peaks 1 . 61 50 . 00 0 . 98 0 �age 1 � i KCR'"S ?rogram. . .�ile �irector�: C:\KC SWDM\KC CATA\ [C] CREATE a r.ew Time Series ST - - 4.60 0.00 0.000000 Ti=1 For�st 0.00 0.00 O.OQ0000 Ti�l Pasture 0.00 0.00 0.000000 Tiil Grass O.QO 0.00 O.000000 Outwash Forest 0.00 0.00 O.00C000 Ou�wasa Pastu_� 0. 00 0.00 0.000000 Outwasa Grass 0.00 O.CO Q.00000o Wet�and 0. ^v0 0.00 C.�OOGCO =mperv'_cus Q00�3r.ex.ts� 1.00G0�� [C1 CREATE a zew T_me �e_�2s �T O. CO O.CC O.000000 T;1_ ccres� O.CO O.GC 0.000000 Til? Pas�ur� 1.39 C.00 0.000000 Till Grass C.�O 0.00 0.000000 Outwash �'cr�s� C.00 0.�0 0.000000 Outwash Pas��.:re C.00 0.00 0.000000 Cut�Nash Gras� 0.00 0.00 0.000000 Wetlanc 3.21 �. 0� O. �nr000 Im�ervi�us 00053ndev.tst T i.00000 T fT; En�er t:�_� ��-�al,�sis TCCL� `^.c:ule [P; Compute ?�'�iCS ��:c F�ow �raq��encizs 04053nex.tsi 00053rex.pks [P] Compute FEP_KS and c_�w Fr�cueac_es 00053ndev.tsf Q0053ndev.nks [D] Compute _lew �URATIGti and Exceecer_ce 00053ndev.ts= OGO��ndev.cur F F 35 0.330000E-0= 0.?51000 [D] Compute Ficw uL�`"=�D1 a^d ?,���eder.ce OOG53nex.tsf GOC'�3r.target.dur F F 3c C.800000E-�.`',� u. 640000E-0= jR] RETURN to Fre�T;o�:s Me:�u 7 �,nter Tocls �Iodu?e [Dj Compute :-_ow CU�?_T=ODI ar_d =.�c�eden�� . 0�05?nex.ts= 00053ntarget.dur 0 �eturr. to Main Menu i;r] Size a �etent�cn/Detention FACI�IT� �anual Design _ _ 00053nvl�.rdt 00053nvltrdout.ts` 00053nvltrdou�.dur 0 Return to �a:n Menu (C] CREATE a new Time Series ST 1.70 0.00 O.000000 Till Forest 0.00 0.00 C.000000 T-�11 ?as�ure 0.00 0.�0 O.000000 T�11 Grass 0.00 0.00 O.000000 Outwasr Fores� O.OJ 0.00 0'.CO0000 OLtwash Pasture G.00 0.00 O.CO0000 Out�aash Grass C.00 0.00 O.OG0000 Wetland C.00 0.00 O.00OOOC �moer�ious G0053ce�.tsf 1. 00000 T [C] CREA^'E a new Time Series ST O.00 �.00 0.000000 Tiil Forest , 0.00 0.00 O.OG0000 Till Pasture 0.39 0.00 0.000000 Till Grass O.CO 0.00 O.OGC000 Outwas� Forest 0.00 0.00 C.00C000 Gutw�sn Fasture 0.00 C.00 O.000000 Cutwash Grass 0.00 O.00 0.000000 Wetland 1.3� O.00 �.000000 Impervicus 00053cdev.tsf T 1.00OOC T �'^] =nter the Analysis TOOLS ylodu=e [P] Compute PEAK� and �1cw Frequer_cies C0053cdev.tsf C0053cdev.�ks [P] Ccmp•ste rEAKS and F1ow �requencies 00053cex.tsf 00053cex.p;�s �D] Compute Flow DURATION and Exceedence OOG53cex.tsf 00053ctarget.du; [D] Compute F_ow CURA'_"ION anc 3:�c2?CEr1C2 COCSJC@X.�S= C0053Ctarg.uur F [R] RETUR:1 r o =re-;i�us �.Ten� ��� .S1Z� c �2t�IlL. �r _'_ �_.- . -._ ' r. c�1tORl3L1C Design 0��053cv1t.rd= [r] Size a Ret�ntian/Detention �ACILITY 0 Retnrr. �c �ain Menu [F] S_ze a Re�ention/Detention FACI��TY Manual Design 00053rvlt.rd� 00053rv1t�dCut.tSr 00053rvltrdout.dur ' F � ' G Return to �ain Menu [X] eXit �CCRTS Program � '� . I j � � � �'ac�ity S�ing � �low �ur��on Cu�ve ��t �roject: 00053 Coibblestone/Fourth Stre�t Plaaa Commercial Site Infiltration/Detention Vault The infiltration rate is reduced in order to model the reduced infiltration area. The infilCrarion rate is adjusted proportional to the percentage of infiltrarion area to the total area of ti�e vault layout The adjustment factor is refined though iteration. Final design will achieve the volwne required. 28'x46' = 1,196 SF,Footing area=(2*X*1'+2*(46-4 )*(1'+2,75')+Y*2' ) ,X=28',FA=�27 SF �I Actual infiltrarion rate=2.75 in.�hr.or 21.8 min.!in. Adjusted infiltration rate: (1,196 SF—427 SF)i 1,196 SF=0.6�t3 of actual,3 5.7%reduction. :�djustment yields an intiltration rate of 1.?68 in.;'hr or�393 minrinch. Finai Vault size: 28' x 46', split into 2 cells File: OOQ�3svlt.rdf By�� -. e . ->: _��. N . r Q .._..__ _ .'�l.i`�,_Ji.'...;r �,: . _�°;�:�:��:�.:r��'t .i�r ♦ � - c '��,. , � o `i► ao R .--�`�^"-'C —. o ;�►' � o �� U ! r; � � I �� � � � � � t N `�� — v `�r , a a � Y���. �. N � O �' O ":R. � ,-;� Q � �_�'``'�_._._.,� ��=�, � , , , � r='�-rrr-�—r-r-�riT �10 '' 10 -a .10 -a 10 -� •lp "t �0�� Frobabiiiiy Exceedenc� ,�,.._��_ :�'�►` .i��t�:3�'�i;a�R��� ;_�'K �. ���n , �P_:..�F:.: �ht.. :3J:E- ;�Q -���.11�c.� I:�,'000\0005�\EagrKCRTSVRB�00053cv1t Duiation Curve.doc 01/10/02 Re��ntion/Ce�enticn _=aci'�'_ty Type of Faci'i�y: In=i�tration Pond Side Slcpe: 0.00 H:IV , Fond Bottom Length: 46.00 ft Pord Bottom Width: 28 .00 f� Fond Bo�tom Area: 1298. sq. ft Top Area at 1 f_. nB: 1288 . sq. tt 0.030 acres _�`ecti7e Storage De�tz: 7.00 =t , Staae 0 Elevation: 383.50 `t Storage Vclume: G016. cu. =} 0.20? ac-ft Vertical Per_neability: 33. 90 mir./in Per.neable Surfaces: Bottom Riser Head: 7.00 ft 3iser Diameter: "_2.00 inches Nu�-nber cf cri*_ces: 2 Full Head Pipe Orii'_ce # I�eigh� �iameter Discharge Diameter (=t; (in} (CFS} ;_n) 1 O.GO �.94 0.063 2 2.50 G.65 C.027 4 .0 "_'op �c�ch Tr7eir: Ncne Cutflow Ra�ing �urve: �Tone Stage Elenat'_en StcrGge Discharge Fercolaticn Surf ?�r�a (tt; (ft) {cu. fti (ac-tt) (cfs) (cfs; (sq. rt) ' Q.00 383.50 0. 0.000 0.000 0.00 1288 . G.Ol 383.51 13. O.00O 0.002 0.05 1288 . 0. 02 383.52 25. 0.001 0.003 O.Q5 1288 . 0.03 383.�3 39. 0.001 O.00a 0.05 1�88 . 0.04 383.54 52. C.001 0.005 0.05 =288 . O.CS 3�3 .5:= od. G.001 0.005 0.05 i298 . 0.06 383.5'0 7�, 0.002 0.006 0.05 1288 . 0.0? �83.57 90. 0.002 0.006 0.05 1288 . 0.08 383.58 103. 0.002 0.007 0.05 1288. 0.2C 383.7�� 258. O.OGb 0. 0=1 0.05 1288. G.32 38s.82 412. 0.009 O.C_3 0.05 1288 . 0. 43 383.93 5�4 . 0.013 O.C16 O.CS 1288 . 0. 5.; 384.05 708 . O. �i6 0.018 O.CS 1288 . 0. 67 384.1; 863. O.C20 0.020 G.OS ;298 . 0.;9 384.29 10'_8. 0.023 0.021 0.05 �288 . �' 0. 91 384.4� 1172. 0.027 0.023 0.0� i288 . 1.03 384.53 1327. 0.030 0.024 0.05 1288 . 1. 15 384.0'S _a81. 0.034 0. 026 0.05 1288 . 1.26 38?.76 i623. 0.037 Q.027 0.05 1288 . 1.38 384.88 177?. 0.041 0.028 0.05 1288 . 1.50 385.00 1932. 0.��44 O.C29 0.05 1288 . i.62 385.Z2 2087. C.Oa8 0.030 O.Q� 1288 . ' 1.;4 385.24 2241. C.051 0.031 0.05 1288 . 1.86 385.?6 2396. 0.055 ��.032 0.05 "_283 . ' 1. 98 385.48 2550. 0.059 0.034 0.05 1288 . '' 2.10 s85.50 2705. 0.062 Q.0�5 0.05 12^c9 . � .�1 ��5.i1 G3� i , U.ubJ V. �.;� 0. �� _._�C � .33 385.83 300_. O.Ob9 0.036 O.CS i238 . .% .?5 38�. 95 3�50. O.C72 0.037 0.05 1288 . �.�0 380.00 3220. u.0?4 0.038 _ 0.05 I288 . 2.5i 386.Q� 3233. 0.074 a.038 0.05 1288 . 2.52 38E.�2 3246. O.OiS O.G39 0.05 128? . 2.53 385.03 3259. 0.�75 0.039 0.05 i2�� : 2.54 3EE.��4 3272. 0.0?5 O. Ca� 0.05 1288 , �.55 386.05 328a. 0.0?� O. C41 O.CS i288 . 2.56 386.06 3297. 0.0?6 0.0�1 0.05 1288 . 2. 68 386.18 3452. Q.075 O.DaS 0.05 1288 . 2.�0 386..s0 3600. �.J83 0.097 �.05 1288 . 2 .92 386.42 ?761. ��.��86 0.049 �.OS 1288 . 3.O�1 386.5a 3910. 0.��90 0.051 0.05 1288. 3.15 386. 60 4070. 0.093 0.053 0.05 1238. 3.28 386_78 4225. O.OG7 G.054 0.05 1288. 3.39 386.89 43`06. 0._00 G .056 O.uS 1288. 3.51 387.01 4521. O.;Oa 0 .058 0.05 12�8 . 3.63 387.=3 46?5. 0.107 0.059 0.05 12�8 . 3.75 387.25 48.s0. 0.1"_1 0 .061 0.05 1288 . 3.87 387.37 4985. 0.1'4 0.062 0.05 I288. 3. 99 387.49 5139. 0.118 0.063 0.0� '_288. 4.=1 387. 61 5294. 0.122 0.065 0.0� =288 . 4.23 387.i3 5448. 0. 125 0.066 0.0� _L88 . 4.34 387.84 5590. 0.128 0.067 0.05 �288 � a.46 387.96 5745. 0.?32 0.068 0.05 1288 . 4.58 388.08 5899. 0.135 O.C�70 O.C5 12�8 . Q .iO 388.2C 6054. 0.=39 O.Q71 O.CS 1288 . 4 .82 38E.32 6208. 0.143 O.G72 O.CS 1288 . 4.94 38�.44 6363. 0. 1�6 0. 073 Q.05 1288 . 5.06 38�.56 6517. 0. 150 0.074 0.05 1288 , 5.17 38� . 57 6059. Q.l�.s 0.075 0.05 1288 . 5.29 388 .79 6814. ,�,.1�6 0.07E 0.05 1288 . 5.41 388 . 91 5968. .^,.lou 0.07? 0.05 128E , 5.53 389. �3 7'23. �.164 0.078 0.05 i28� . 5 . 65 389. 15 ?277. 0.167 O.C79 0.05 1288 . 5.?7 389.27 ?432. O.lil 0.080 O.CS 12880 5.89 389.39 ?586. O.li4 0.08i. O.C5 12C8 . 6.C1 389.5i ??41. 0.,?8 O. G82 0.0� 1288 . 6.12 389. 62 788?. 0._�_ 0. 083 0.�� 1288 . 6.2? 389.74 80?7. 0.;35 C.C84 0.0� 1288 , 6.36 389.86 81G2. O.i�8 O.C85 �.0� 128-3 . n.48 389.98 8346. O.i92 0.0�6 �.05 1283 6.6C 390.10 8501. Q.195 0.087 O.Q5 i28u 6.72 390.22 8055. 0.195 0.088 0.05 �28c^ 6.84 390.34 8810. 0.202 a.089 0.05 "�28� 6. 95 390.45 895�. 0.206 0.090 0.05 1288 . 7.00 39G.�0 9G16. 0.207 0.090 0.05 1286 ?.�0 390. 60 9145. 0.210 0.399 0.��5 128� 7.20 390.i0 9274. 0.213 0.963 0.0� 128� 7.30 390.80 9402. 0.210 �. 690 0.05 i28c 7.40 390..0 9531. 0.219 2. 490 0.05 128c 7.50 391.OG 9660. 0.222 2.770 C.05 128�= ?.50 391.'_0 9789. 0.225 3. 02C C.05 I288 7.?0 39Z.20 9918. 0.228 3.200 �.05 1288. i.80 391.30 10046. O.L31 3.480 0.05 i238. " 7.90 391. 40 10175. 0.234 3. 680 0.05 =�38. 8 .00 391.�� i0304. 0.237 3.880 0:05 i288. i 8 .10 391. 00 iC433. 0.240 4.060 C.05 i288 . 8 .20 391.70 10562. 0.242 �.240 L.OS 1288 . 8.30 391.80 10690. �.245 4.410 _ O.CS 1288 . 8 .40 391. 90 10819. 0.248 9 .58C O.CS 1288. 8.50 392.00 '0948. 0.251 4 .73C 0.05 1288. 8.60 392.10 1y077. 0.254 4.�90 0.05 �288. 8.70 392.20 1?206. 0.257 5.030 0.05 _288. 8 .80 392.30 11334. 0.250 5.180 O.G� 1288 . Hyd Inflcw Out�low Fea:{ Stcrage Target Calc �taae Elev (Cu-Ft; {Ac-Ft) 1 0.70 ******* 0.5i 7.13 390. 63 9183. 0.211 2 a.3� 0.;1 0.09 6.92 390.a2 8919. 0.205 3 0.38 *�**x** 0.09 6.44 389. 94 8292. 0. 190 4 0.49 ******* �.09 6.93 39G.43 8930. 0.205 � 0.42 x****** O.C7 4.79 388 .29 61?1. 0. 142 6 0.4C x***�** 0.06 3.38 386. 88 fl356. C.100 7 0.30 �****** 0. 03 1.89 385.39 2437. O.OSo 8 0.33 ******* 0. 03 1.98 385. 48 2547. 0.058 I I i I ,I I I 00053c�x I' �low Fr`quency r.nGlysis T-_me Se�ies File: 00053cex.tsf _ Pr�ject Location:Sea-Tac - - --�rinual Peak Flow Rates--- --- --Flow Frequency Analysis------ Flow Rate Rank Time oi Peak - - Peaks - - Rank Returz Prob (CFS) (CFS) Period 0 . 107 2 2/09/O1 18 : 00 0 . 137 1 100 . 00 0 . 99 0 0 . 029 7 1/06/02 3 : 00 0 . 107 2 25 . 00 0 . 96 0 0 . 080 4 2/28/03 3 : 00 0 . 083 3 10 . 00 0 . 90 0 0 . 003 8 3/24/04 20 : 00 0 . 080 4 5 . 00 0 . 80 0 0 . 047 6 1/05/05 8 : 00 0 . 069 5 3 . 00 0 . 66 7 0 . 083 3 1/18/06 21: 00 0 . 047 6 2 . 00 0 . 50 0 0 . 069 5 11/24/06 4 : 00 0 . 029 7 1 .30 0 . 23 1 0 . 137 1 1/09/08 9 : 00 0 . 003 8 1e10 0 . 09 1 Computed Peaks O . I27 50 . 00 0 . 98 0 Page 1 �00053cdev Flow Frequency Analysis T=me Series File: 00053cdev.tsf _ Project Lccation:Sea-Tac - � ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------ Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prcb (CFS) (CFS) Period 0.353 6 2/09/O1 2 :00 0 . 702 1 100 . 00 0 . 99 0 0 . 298 8 1/05/02 16 : 00 0 .486 2 25 . 00 0 . 96 a 0 .422 3 2/27/03 7 : 00 0 .422 3 10 . 00 0 . 90 0 0 . 334 7 S/26/04 2 : 00 0 .400 4 5 . 00 0 . 80 0 0 . 400 4 10/28/04 16 : 00 Q .376 5 3 . 00 0 . 66 7 0 . 376 5 1/18/06 16: 00 0 .353 6 2 . 00 0 . 50 0 0 . 486 2 �0/25/06 0 : 00 0 . 334 7 1 . 30 Q . 23 1 0 . 702 1 1/09/OS 6 : 00 0 � 298 8 1 . 10 0 . 09 1 Computed Peaks 0 � 630 50 . 00 0 . 98 0 Pag2 1 - - - - — I� I �IV. C�1V���:'�CE S�'S'd'EM P�iTAi.YSIS ANI) I3ESIG�I: The conveyance system for the site was designed for both the 25-year, 24-hour storm, and the 100-yr, 24hour design storm. A conveyance spreadsheet was generated for the 25-year storm using the rational method to calculate flows for each azea collected by each catch basin. The precipitarion rate for the 25-year, 24-hour storm is 3.46 inches. The precipitation rate for the 100-year, 24-hour storm is 3.9 inches. A weighted C value for the rational method was used for each area collected by each catch basin. The average C value for the developed site is_ (1.39*0.25 + 3.21*0.90)/4.63 = 0.70. The attached Storm Conveyance spreadsheets show that no pipe segment in this design will contain flows that exceed their capacity for either the 25-yeaz or 100-year stonn events. Therefore, backwater calculations were not necessary. The conveyance between the water quality and infiltration cells within the combination R'D vault have been designed to maintain the highest water level within the water quality ceils. The flow-through pipes have been designed based on the Uniform Flow Analysis Method. The sizing was based on 4-inch pipes that would convey the 100-year storm flow rate. According to the equation, the maximum flow rate for a fully submerged pipe with 0.5-ft headwater elevation, is 0.194 CFS. Therefore, the n�ber of flow throu�h pipes necessary to pass the design flow rate is 9. - -- -- - - �- ->.� - -- - - ��`�'CPl�1�'I��C�N�I'�N��h: �a�'4`�',I�.M��l3TS1+[��I � � �i �a����������rv: � �,:��v��x��yr�r���� z�i-�s����i�rr�,��i. � 3.� trtr��ii�;s ���� I _ _ ,, .r�)t�N�h1�;� �C Ok3��l�.r 5"�'c�NI: �� � JOf�N�)nI�GR; 000S3 � � � Px►�,rnR��a 131t� ,►Itk3 I�l�S�c�iv�I�)i�11i; 2,� �'1�:,�1� INCHEI�EN1TAl HUNOFf WIPENVIDUS iIR�E OF RAIf1�All TRIBIITARY PIPE PWE FU'E AC1UAl THAVFl � PIPE CAPpCITY SUMNIARY ���i AREA CQEFFICIENT AREA 81MH OF I�NC. WTENSIT� FLOW II�IANNINC'8 OIAMETFA SLOPE L�IICiH VFlOCITr TWIE QfFUlll V[FULU p[ACiI/Q(FIKU fROM 1� i0 CB [IICRE81 "C" [A*Cl U*Cl [NWUiESI [1N/NRl [Cf8] "n" [WCIE81 [PfAI�NTI [Fffn (FT/BECI [IUWU1E81 (CF8l ffT/BECI [PEACENTI r �. S ^ro �,�. ���� a�'?d�f. 18 17 U.270 0.70 0.169 0.189 10.00 2.02 0.383 OAl2 12 I.SU 100 3.55 0.47 4.727 ti.02 8.1% 17 16 0.275 OJO 0.192 0381 10.47 1.97 0.749 0.012 12 L50 122 4.18 0.49 4.727 6.02 15.8% Ifi ti U.]7K U./U O�h� U.alb IU�)h I'll I 't} UUIL I' O.UU UUU U.UOD UUU UUY� � _.._.,.�.. �_ � ^.�._.,. ._..� -- r �.. _ , .. ., .. -';...._��.�. ._.- r,,. � , _ . � ' . p � . .: .. ., . . + ," ,�_ � t.,a.i-. .� '. . � -.::. �.. � ,:� � .���, ,. � ' ' '��- ' '� � r�. IS I 1 0_i">:I 0 7U U'_27 U 3?Y IU UII �_02 Il d�'1 11111? II �bU �I.! q a8 (Ll6 6�.!2! 7J_ 7_�!`;b 14' ll Q209 U.70 O.147 0.373 10.16 2.00 0.74K U.012 12 O.OG 0.00 QUW 0.00 0.0°�0 ' 13 l2 0.311 0.70 0.218 0118 10.00 2.02 0.441 OAl2 12 1.60 186 3.76 0.82 4.882 622 9.04�0 12 11 0260 0.70 0.182 U.400 10.82 L92 0.769 0.012 12 OSO 24 2.9'/ 0.1'! 2.729 3.47 282% 11 10 0.001 U.70 (1.001 0.77A 10.96 1.91 1.47G 0.012 12 1.50 93 5.24 03U 4J27 6.02 31.2% 10 9 0.140 0.70 OA98 0.871 11.25 1.87 1.634 O.OI2 12 1.60 61 5.50 O.18 4.882 622 33.Sio ) 8 0,186 0.70 0.130 I.001 11.44 1.86 1.858 O.U12 12 1.56 84 5.71 0.25 4.821 6.IN' 38.5% 8 7 0.177 U.7U O.124 1.772 11.68 1.83 3242 0.012 12 Ll5 27 5.85 0.08 4.139 5.27 78.3% 7 I 0391 0.70 0274 2.045 11.76 1.82 3.727 0.012 12 7.20 77 11.87 0.1! 10357 13.19 36.0°u S 6 5 0.24U 0.70 0.168 O.168 10.00 2.02 034U U.012 12 4.4U 94 4.90 032 8.096 1031 4.2% 5 4 O.176 0.70 0.123 0291 1032 1.98 0.578 0.012 12 0.50 60 O.OU (1.00 2.729 3.47 21.2% 4 3 UAL7 0.70 UA12 0303 10.32 198 0.601 0.012 12 Q50 74 2.78 Q�14 2.729 3.47 22.0% 3 2 0,216 0.70 0.151 0.454 10,76 1.93 0.876 0.012 12 0.72 131 3.50 0.62 3.275 4.17 26.8% 2 1 0349 0.7U 0.244 0.698 1139 1.86 1.299 OAl2 12 6.50 l37 8.33 0.27 9.840 12.53 13.2% 1 VAULT 0287 0.70 0.201 2.67U 11.66 1.83 4.893 0.012 12 20.00 13 18.79 0.01 17261 21.98 283°.0 9/10/O1 CORE DESiGN, INC. 1 _ -- -- --- - ---- - -- -- -- _ -- ,.�:.--- �'I',C)l�M C�)NVi+:,YAI�('I�, �'Xti'i'GM �ES[(�N �� � t.r�c�,�Tas�iv: a.��v�c,c�c��i������ � � z�-�r�t�naN�r�r�i.�,: �a.�� rNc���ii;� .�r�a�iv;A��H,�: r�»t�i:�.5�rr�i�� � � � � .i�»�Ni��nn;��;���: onos3� � � � �r��E.�+��7ii�u���: ��.iui� � �� � �� �� � n��'Sic�iv sroun�: �����►9 >'�a� �YWttAMEN1Al NI�IOfF W�'E�VIOUS TUINE OF RAINFAII iRIBUiNBY 4'I�E PIPE PI�E ACiUAI TRAYEL PIPE CAPACITY SUMMAfl11 ���T ANEA COEFFN�fNT AREA SIaW OF CONC. WIENSIT� fLOW MANNY�'8 DIAMETER SLOPE LENCTH YELOCITI TN�E Q[Fill11 Y[FUIU Q[ACT1/Q[FIIIU FROM I� TO CB [ACRESI "C" [A*C) [II*Cl [MINUiESI [IN/NRl CI�SI "n" [d�plESl [PERCENTI [FEED [FT/SECI [MaWIESI [CF8l (FT/SECI [P�ERCENiI '' d c �r S'.i� �,...,� +h 73« .� �'� ' �'�S'�.t,�'..� Yr„&;.�.t �t" �k ..,7*i'r s�'R #'�L,� IS 17 U.270 0.70 0.189 0.189 IQOU 23) 0.451 0.012 12 I.50 100 3.64 UA5 4.727 5.02 9.5% t7 16 0.275 0.70 Q192 0.381 10.46 2.32 0.864 0.012 12 1.50 122 D.00 0.(10 4.727 ti.02 18.7% 16 8 0.378 0.70 0.265 0.646 10.46 232 1.49I 0.012 12 U.00 U.00 O.OW OAO 0.0"0 �'�x , s � �.�^'�.�3ti�'a s.': =an�n �,. L��=�� a., 15 14 0.324 0.70 0.227 0"?27 10.00 239 0.541 0.012 12 2.6U 44 4.68 0.16 6224 792 8.7% � 14 11 0.209 0.70 OJ47 0373 10.16 236 O.SS2 0,012 12 0.00 0.00 U.OW 0.00 0.0% - � i x �:; I.l 12 0311 0.7U U.218 0218 10.00 2.3N 0.520 OAl2 12 l.ti0 166 3.92 OJ9 4.882 6.22 10.7% 12 I l 0.260 0.70 0.182 0.40U 10.79 227 O.y09 0.U12 12 O SU 24 3.OK 0.13 2.729 3.47 33.3°io ll 10 OA01 0.70 QUUI 0.774 IU.92 2.26 1.746 Q012 12 1.50 93 5.51 028 4.727 ti.02 369°0 10 9 O.140 0.70 0.098 0.2571 1120 2.22 1.935 U.Ul2 12 1.60 61 5.78 O.18 4.882 622 39 6% ) 8 0,186 0.7U 0.130 l.O(Il 1L38 2.20 1.858 OAl2 l2 1.56 84 5.71 U.25 4.821 6.1'4� 38.Sio I� 8 7 0.177 0.70 O.124 1.772 11.62 2.17 3.2�2 0.012 12 1 J 5 27 5.85 0.08 4.139 527 763% 7 I 0391 OJO 0.274 2.0�5 11.7U 2.16 4A21 0.012 12 7.20 7� 12.59 0.10 10357 13.1) 42.7% ' ;t ,AXN i� y��. ,et�; 6 5 0 240 0.70 0.168 0.168 10.00 2.39 OA01 0.012 l2 4.40 94 4.IU 0.32 8.096 1031 49°/u 5 4 0.176 U.70 0.123 Q291 1032 234 0.682 0.012 12 U.50 60 2.65 0.35 2.729 3.QZ 25.0°/ 4 3 U017 0.7U 0.012 0.303 IQti7 2.29 0.69� U.012 12 U.50 74 2.85 0.43 2.729 3.47 2�.4% 3 2 0216 0.70 O.151 0.4)4 I1.10 223 I.Ol4 0.012 12 OJ2 131 3.63 0.60 3.275 4.17 31.0% 2 1 0349 0.70 0.244 0.698 11.71 2.16 1.509 0.012 l2 6.50 137 8.71 02ti ).840 12.53 15.3% I VAUL"f 0267 U.70 0.201 2.670 11.97 2.H 5.690 0.012 12 20.(NI 13 19.45 0.01 ]7261 21.98 33.0°�0 9/10/O1 CORE DESIGN, INC. 1 — -- ----- ------ ---- — ---- �TORM C'QNVI��YA�J(��F; �1'STEM I�ESIGN r,��:n't��oN: hiNc:c��u�v�r�r� 2a-��iK iiniNf��ai,i�;� �,a �Nc.���a:s � 1 JOB I�IiMl31_,kt: UOU53 PREI AI2i��D Bl': .IRi3 [l�Sl(.'N 5"fCl�2iV]: 2S �'EAR JOK N��I1:: 4T11 ST PI.AZr � ' PiPE sE�MENT �r�cH�Mtr�ir,� RUNOFF IMPERvio�is TIME OF RAINFAI I iwieuiaf�v PIPE PIPE PIPE ACTUAL TRAVEL f'IPE CAPACITY SUMMARY AREA COEFFICIL=NT AREA SUMOF CONC. INTENSITY FI OW MANNINGS DIAMETCR SL(�F'E IENGTH VHOaIY TIME Q(FULL) V(FUII) Q(ACT)/Q(FULL) raoMca TO ce (ACRES) "C" (A*C (A`C) (Mwu�ts) (IN/HR) (CFS) "n" (wctiEs) �Fekctr,>> (FEET) (FUSEC) (MiNUTEs� CFS) (Fr/Stc) (PERCENT) s: ,"r�S.,,_t:`�,�v�S°u.n d�3�`�,,�,.�.rf�'�r. �S *arC.. �q•r m � a,�� .,���"w � � � �?.�,.F�'."ti�.k` S-4 S-3 U 720 090 0.64K U_6aR 1LLUu 2.0)_ 1.312 0.012 12 4 U0 �0 7 13 0.12 7J1) 9 H�l 12U9�b S-1 V�1U1'I u_iUU U��U U�a�li 1332 IU I� ?Ol ?b77 U.UI? 11 4 UI1 It;u S.UU U37 6 hK� h il �U U';�� 5-5 S-3 U 260 U�)U 0.23� U.23a IU UO 2.U1 U�1%-1 U 111? I? 11.70 bU 2 t;6 0 iJ 1 L�9 d.l l N.790 u r�, e�. �� �'3�^ + .s: ��: S-6 VAUI:f ILOqO 0.J0 0.036 0.03ti 10.00 202 OA73 O.Ol2 12 20.00 8 OAO Q00 172G1 21.96 0.4% j R!)l.D Dli NOTES'JUNC'T/ON C81 1/23/02 CORF, nrSIGN, INC. 1 IV. E��S��N C�3N'�'?R�L ��LC�:�.�TI�1�� The intent of this erosion and sedimentation control plan is to minimize erosion and the transport of construction reiated sediments off-site. The following ESC measures are incorporated into the Erosion Control design: 1. Clearing Limits: Clearing limits have been delineated on sheet C2.01 of the I clearing and grading plans. The clearing limits extend only to those areas that will be disturbed during construction of the subject project. In general, clearing limits eYtend�around the subject property. 2. Cover vleasures: The temporary erosion and sedimentation control notes listed on sheet C2.31 specify specific times at which temporary and permanent cover measures will be installed. 3. Perimeter Protection: Per sheet C2.01, silt fence will be used for perimeter protection. Silt fence will be installed along the perimeters of those areas that will be receiving silt-laden runoff. 4. Traffic Area Stabilization: A construction entrance will be installed at the entrance to the project site. See sheets C2.01 and C2.31 far location of construction entrance and detail. 5. Sediment Retention: The detention/water quality vault will be used for sediment retention. Sediment retention will be desianed per the 1990 KCSWDM. Se�iment Pond Calculations The runoff tributary to the sediment pond was calculated using WaterWorks hydrology software utilizing SBUH methodology. The soils on site consist of :�lderwood material (AgC} according to the King County Soil Survey. The site is considered to have pervious soils exhibiting characteristics of Type C soils. The precipitation rates used for this analysis are as follows: 2-year, 24-hour storm —�2.00 in. —used for sediment pond sizing �-year, 24-hflur sto�n � 2.90 in. —used for riser sizing During the erosion control phase of the project, the site will be entirely cleared and will therefore be modeled as bare ground. The following information was used �o create the runoff hydrograph for the residential portion of the site with Waterworks using SBUH methodology: EROSION CONTROL P�SE ; GROUIVD COVER AREA(acre) CN I Bare Ground 7.6 87 ' TIME OF CONCENTR.�TION Assumed 10.00 min. The resulting hydrographs are: 2yr= 0.95 cfs l0yr= 1.89 cfs See attached WaterWorks hydrograph printout Two TESC ponds will be constructed for the site, each of the same size. The size is based on the residential (larger) portion of the same size. Therefore, there will be more ' treatment of the runoff than required. Surface Area: SA= 2080 sfi'cfs * QZ Q� = 0.95 cfs SA=2080 sfi'cfs * 0.95 cfs = 1,976 SF The designed sediment pond is 70' x 30' at the standpipe overflow elevation SA=2,100 SF > I,976 SF � OK Pond Geometry: North Pond The bottom of the pond is at elevation 376.0. The top of the sediment storage is EL 377.0 (1 foot of sediment starage). The elevation of the top of the standpipe is EL 381.0, yielding 4 feet of depth. The berm elevation is 382.0. South Pond The bottom of the pond is at elevation 389.0. The top of the sediment storage is EL 390.0 (1 foot of sediment storage). The elevation of the top of the standpipe is EL 394.0, yielding 4 feet of depth. The berm elevation is 395.0. Both Ponds 3:1 interior side slopes 4' depth 1' freeboard :�,JC'� '�i�l'.. Design Fi��� = P:-�-�i��,�lup�u �% �- : .=<.'-' �t` �le flOW CSpSCl� tOL a 17 � CI13111�tZT' T7SeI' `.��1t�1 I `O��i ��C I1:;1�1 :� �l'J��I'�.�-::17�:.i�.'l.� � 4cfs » 1.89 required. OK. EmerQency Overflow Spillway: Design Flow =Developed Q,00= 1.65 cfs ; H = 0.2' L = (Q,o�/3.21H3'Z))-(2.4HZ)_ (1.65i0.287) —(0.096) = 5.65' The overflow spillway prescribed on the plans is the minimum 6' wide, greater than the 5.65' required. Dewatering Orifice: Orifice area =AS(�h}0�5/(0.6}(3600)Tgo.s _(1,976)(2*4)05/{0.6)(3600)(24)(32.2)0' = 5588.97/294166.3 = 0.019 sf Orifice diameter= 24(orifice area/�)°�' (1 inch minimum) = 24(0.019i;�)o' = 1.86 inch. �onversion of vaults to sedimentation facilities lipon completion of the north reinforced concrete R/D vault, the TESC facilities will be directed to the vault and the TESC pond will be filled. The sedimentation residence rime requires a surface area of 1,976 sf to provide sufficient sediment removal. The surface area of the water quality cells of the vault is 2,240 sf and the protected infiltration cell will provide additional surface area of 1,120 sf, for a total surface area of 3,360 sf. The infiltration cell of the vault will he outfitted with geotextiles to prevent siltation of the native soil. t;pon completion of the south reinforced concrete R D vault, the TESC facilities will be directed to the vault and the TESC pond will be filled. The sedimentation residence time requires a surface area of 1,976 sf to provide sufficient sediment removal. The surface area of the water quality cells of the vault is 1,196 sf and the protected infiltration cells will provide additional surface area of 1,288 sf, for a total surface area of 2,484 sf. The infiltration cells of the vault will be outfitted with geotextiles to prevent siltation of the native soil. _— —,_ � � � -- ,��p -- °'"�"' 6.P.L/RM.S. N/A �"' �� CITY or ���.Y, zooi � """"""` -- � �' R�N'1'ON s�TH AN1J UNION "� � AGD - � �: �-"—"`�w"-{ oAT�M EROSION CONTROL PLAN � �' Plannin_g/9uil4fng/Public Workc pupl. J0� � REVISIOIJ BY DAIE APPR �4� �����. Gregg Zimmerman P.E., Adminialrator -- R.II.STEVENS �i;� I C2.01 6 I �& ; � I ' � ESI� I a I �� ; ��'������ � � � ��8 � � '������� ^t� � ���8 R � � ti� � �� � P�n PPg� � � � ��o' � '� � e���'�'~� #��� ,��9,�, ������� � `��� � � I a� �•"�� �1 � N N � ` � � � ��1���], ��y v�� � �"1������ N � ��� � .1 \ \ � I� / � � V � ��J � � �� S �i' ` � � ���N � A I . I.� �� � \. C� g� � �� td O � r��n� F�1_ -� . �- � ^1 ��.C� �fn m� � I � I r;iy i ti� 2 (��� u��� i C.� � I ��' �'� - r� _� � � "�` gs� ' � � � � _J ,- �- � \` �� �� /i�--- -- ---�_ ; " �I. � �� — — — d -- __ t . � _��`-- �mmi� 4"'� � ` _ . 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