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Home My WebLink AboutSWP272734 SwP• 2`� • Z7 34 CONCEPTUAL DRAINAGE REPORT FOR KIRKLAND COURT Prepared for: Treece&Company 320 Second Avenue South Suite 200 Kirkland, WA 98033 Prepared by: Peterson Consulting Engineers 320 Second Avenue South Kirkland, WA 98033 9 F.A PET 10N AL gt� l�XPtRES H 17/ September 10, 1997 � T Page 1 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PROJECTPART f. '.PROJECT OWNER AND .- D�/ Project Owner ;l`, L9 f ti L' Project Name I' �ioez,z ND U12w/ Address IP9 ,f. ' O E 9 Location �7�;A/ Phone Township Project Engineer AWZ- Range E Section Company � F �` � N �N Project Size ��/ETOF./L�� AC Address Phone 'n0 J�U D U.�_ 9 Upstream Drainage Basin Size M� AC PART 3 TYPE OF • ® Subdivision DOF/G HPA 0 Shoreline Management Short Subdivision COE 404 0 Rockery Grading 0 DOE Dam Safety 0 Structural Vaults Commercial FEMA Floodplain 0 Other Other COE Wetlands = HPA PART 5 SITE COMMUNITY AND . Community dIT 11 OF /-?EA,iTON Drainage Basin PART 6 SITE CHARACTERISTICS 0 River Floodplain Stream Wetlands Critical Stream Reach Seeps/Springs 0 Depressions/Swales High Groundwater Table 0 Lake F--] Groundwater Recharge 0 Steep Slopes Other 11-71—.4T Lakeside/Erosion Hazard SOILS Soil Type Slopes Erosion Potential Erosive Velocities Additional Sheets Attatched 1/90 TABLE OF CONTENTS I. PROPOSED SITE CONSTRUCTION 1 II. EXISTING ON-SITE DRAINAGE FEATURES I III. DEVELOPED ON-SITE DRAINAGE FEATURES 1 IV. CORE REQUIREMENTS 3 A. Core Requirement#1: Discharge at the natural location 3 B. Core Requirement#2: Off-site analysis 5 C. Core Requirement#3: Runoff control 5 D. Core Requirement#d: Conveyance System 5 E. Core Requirement#5: Temporary Erosion and Sediment Control Plan 5 V. DETENTION/RETENTION g VI. WATER QUALITY g VIi. OFF-SITE ANALYSIS 7 VIII. CONCLUSION 7 e ' Conceptual Drainage StudyJor Kirkland Court September 10, 1997 I. PROPOSED SITE CONSTRUCTION The 4+/- acre Kirkland Court site is a proposed residential subdivision containing approximately 19 single-family lots. The site is located within the City of Renton, northeast of Kirkland Avenue NE and directly southwest of Honey Creek. More specifically, the site is located within the Northeast quarter (NE 1/4) of the Southwest quarter(SW 1/4) of Section 4, Township 23 North, Range 5 East, W.M. Existing development adjacent to the site includes Renton Highlands No. 2 to the west and north and two mobile homes to the south(see Figure 1). Based on the results of an onsite detailed soil content analysis completed by Terra Associates, the site contains Alderwood soils. This soil type is considered hydrologic soil class C per the King County Surface Water Design Manual (SWDM). Curve number calculations for the onsite hydrologic analysis are included in Appendix I. II. EXISTING ON-SITE DRAINAGE FEATURES The existing conditions within the project boundary consist of heavily wooded area with many scattered trees ranging in diameter from 12" to 30". The onsite existing runoff is divided into two drainage basins consisting of the northeast portion of the site (approximately 1/3 of the total site area) and the southwest portion of the site (approximately 2/3 of the total site area). An existing ridge intersects the site from the northwest to the southeast and defines the boundary by which the two aforementioned drainage basins are defined. Northeast of the ridge, the existing on-site runoff discharges northeasterly into Honey Creek at a steep slope of approximately 75% +/-. This area is within a native growth protection area, and is not proposed to be used for development. Southwest of the ridge, the onsite runoff is discharged at a relatively mild slope of approximately 5% +/-. Please note that the site is only proposed to be developed within the southwest portion of the site. An analysis was completed utilizing the WaterWorks software to determine the existing and proposed runoff rates produced by the 2, 10 and 100 year, 24-hour storm event for the pre-developed conditions. All of the hydrologic parameters utilized in the calculations are included in Appendix I and the results summarized in Table 1. III. DEVELOPED ON-SITE DRAINAGE FEATURES The proposed on-site drainage patterns are similar to those of the existing conditions. The onsite development is only proposed to be located within the 2.73 Peterson Consulting Engineers Page 1 D.\DATA\PROJEC MTREC0003\TREE.DOC Conceptual Drainage Study for Kirkland Court September 10, 1997 • Depth of Flow=0.23 feet • Surface Area= 880 sq. ft. • Velocity=0.20 fps => 100-year, 24 Hour Storm flowrate: =0.89 cfs • Design Swale(100-year, 24-hour storm): • Length=200 feet • Width=3 feet • Slope=2.00% • 'V'Value=0.027 • Depth of Flow=0.14 feet • Surface Area= 770 sq. ft. • Velocity= 1.91 fps Copies of the WaterWorks biofiltration Swale calculations are included in Appendix III. VII. OFF-SITE ANALYSIS The City of Renton Surface Water Drainage system plan was utilized to determine an appropriate off-site discharge point for the proposed Kirkland Court development storm sewer system As shown in Figure 3, an existing stormsewer is located within Kirkland Avenue NE up to NE 16th Street. It is proposed to construct approximately 450 LF of 12-inch storm sewer from the outfall of the detention facility, southwest within NE 18th Street and south within Kirkland Avenue NE to the existing stormsewer discussed above. An alternative proposed alignment may include the construction of approximately 250 If of 12-inch storm sewer from the outfall of the detention vault to the south, bypassing the existing mobile home detention pond and discharging into the existing 12-inch storm sewer within NE 16th Street. This alternative is dependent upon the ability to achieve utility width requirements and easements along the entire alignment. VIII. CONCLUSION Based on the information contained within this Conceptual Drainage Report, the construction of the proposed Kirkland Court subdivision is not expected to create a negative impact on the existing adjacent areas. Runoff from the site will be routed within the proposed on-site street section at an acceptable depth and velocity, conveyed to a detention vault within a biofiltration swale, and discharged into an existing off-site storm sewer system. Peterson Consulting Engineers Page 7 D:\DATA\PROJEM\TR.FCON3\TR-EEJ30C 1 I GRAPHIC SCALE 100 0 50 100 200 400 I rRAc-r NE 1/4, SW 1/4, SEC.4, TWP.23N., RGE.5E., W.M. LAM- RENTON SP 020-91 9303039001 _. ( IN FEET ) � 0� • 1 inch = 100 fl Alp'? P51i £AR)15J3";ar ��l �Ti� �r .' Y •K T �....�.... 41 li 4 iS 10 9 ��' LOT 2 § XCSp 108SO17-960126 86 Vr , s �17 , t♦ 11 i Je rRACT's +, m�cr-c �„ 19 e P. as A as er •01..ar a ail ON—SITE r.a' row.i +~ a DRAINAGE 9.... TRACT-A' 3 Id ! LT 12 - jp0 NCP• PROPOSED IO'DOE pp [ A. ,p t: EYf11fQ/CY KWEI a • ��r 7R�Ci. 44 = y f r ,Eloru6m AtSP IOB50I7- AC.,E SS ROAD fAOUTV 1 b o AREA TO BE _.YIgY fw[ ,ally r•lm $. 1 8 ;2 IS �S ,4 8 s oa'.°.`.ars / VC \ 3 / 4 ,• 5 6 \\ •\ '\\ / RENTON ICHLANDS NO 2 /01- PCS.92-98 lORRE TION PLAT 2 / HLCK4. BLOCK 3 5 / LEGEND NOTE: TREECI— COMPANY fNGINFFp:F.c. AIEV :iN:IiiPYE1+T 1':'Jl?�k15 S.J..'f"'.Itl•K' .vSr,r'J. )'w`:! C'I'CY UF' TtfN'I'ON DF_1'A Rl ME-Nil OI• PUt31.IC WOItK� FIGURE 2 ON-SITE DRAINAGE BASINS AND PROPOSED FACIUTM KIRKLAND COURT as-c o J f Y i Art 9/0/ fllf6v D.• At j 1 _ _ Y } y .—._. _ ND —_. i•M:rM ___ PI -�PIM - Mr-- P rN P _..______- IM 1 Conceptual Drainage Study for Kirkland Court September 10, 1997 acres located-to the southwest of the steep sloped area adjacent to Honey Creek. The project will result in the construction of 19 single-family homes, and vehicular roadways. As shown in Figure 2, the finished site will have approximately 2.27 acres of residential lots (48% impervious) and 0.46 acres of paved impervious (inclusive of both roadway and private access tracts). An onsite hydrologic analysis was completed utilizing the WaterWorks software to determine the 2, 10 and 100- year, 24-hour flowrates generated by the post-developed conditions. The parameters and calculations are included Appendix I and the results of the calculations are included in Table 1. A new storm drain collection and conveyance system will be constructed as part of the project. A detailed discussion of the proposed storm drain system is discussed in the section within this report entitled "offsite analysis." On-site storm detention will be provided, as discussed in the next section, to limit the on-site runoff to quantities defined by the existing drainage condition hydrologic analysis. To provide for water quality treatment, runoff from paved and landscaped areas will be collected and conveyed within a biofiltration Swale located after the detention vault discharge (see Figure 2). TABLE 1 FrequencN Area Volume Pre-Development 2-year 0.18 1.95 2.73 0.12 10-year 0.51 2.85 2.73 0.26 100- ear 0.98 3.85 2.73 0.43 Post-Development 2-year 0.83 1.95 2.73 0.29 10-year 1.37 2.85 2.73 0.47 100-year 1.98 3.85 2.73 0.68 IV. CORE REQUIREMENTS A. Core Requirement#1: Discharge at the natural location The proposed onsite conditions and patterns emulate those of the existing site conditions. The developed onsite runoff will be routed via surface flow within the onsite street section and discharged at the historical location. Peterson Consulting Engineers Page 3 n:\DATAT ROJ ECIS\TRECOM3\TREE-DOC Conceptual Drainage Study for Kirkland Court September 10, 1997 B. Core Requirement#2: Off-site analysis A storm sewer system is proposed to be constructed with the site which will serve to capture the onsite surface flows and route them to an existing downstream stormsewer system (see discussion within Section VII, entitled ccoffsite analysis"). C. Core Requirement#3: Runoff control Runoff control will be provided for the Kirkland Court subdivision with the construction of an onsite detention basin capable of capturing the post- development flow rates and releasing them at the existing conditions peak runoff rates for the 2, 10 and 100-year, 24-hour storm events. Designing the system to the 100-year event resulted in a storage volume of 6,830 cubic feet. A detailed discussion of the design and calculations for the detention determination is included in the next section. D. Core Requirement#4: Conveyance System There are two onsite proposed conveyance systems. The first system is the onsite paved street section, which will route surface flows as shallow channel flow to the southern edge of the site, discharging into a proposed biofiltration swale. The second onsite conveyance is a proposed stormsewer system capable of capturing a portion of the onsite developed flows, discharging into the proposed onsite detention vault described above. E. Core Requirement#5. Temporary Erosion and Sediment Control Plan An erosion and sediment control plan will be prepared for the final submittal of the plans which will serve to minimise soil erosion/sedimentation during the proposed site construction. Temporary erosion and sediment control BMP's will be implemented during the project construction phase. BMP's will include perimeter protection silt fencing (where necessary), stabilized construction entrances, catch basin protection, and permanent cover protection (landscaping). Peterson Consulting Engineers Page 5 D:\DATA\P ROJ ECCS\7RECOW 3\TREE.DOC Conceptual Drainage Study for Kirkland Court September 10, 1997 V. DETENTION/RETENTION A hydrologic analysis of the site was completed in order to determine the required on-site detention necessary to eliminate negative downstream impacts due to development. An analysis was completed utilizing the WaterWorks software to determine the existing and proposed runoff rates produced by the 2, 10 and 100 year, 24-hour storm event and to determine the corresponding required detention necessary to release rates equivalent to those produced by the pre-development condition. Additionally, the WaterWorks software was utilized to determine the required detention storage volume, as well as the required dimensions of the discharge facility. The WaterWorks output is included within Appendix H and indicates that the required on-site detention volume is approximately 6,830 cubic feet. The proposed detention vault outfall will be via a 12-inch pipe. VI. WATER QUALITY As previously mentioned, construction of the proposed Kirkland Court subdivision will create approximately 0.46 acres (19600 so of impervious area subject to vehicular travel (including roadway and private access tracts). Therefore, a biofiltration swale will be placed within the utility easement at the southerly edge of the subdivision at the terminus of the impervious area (see Figure 2). The biofiltration swale will be sized according to the design criteria outlined in Section 4.6.4 within the S WDM. Specific design requirements are discussed below. The proposed biofiltration swale for the Kirkland Court subdivision will be installed at the outfall of the proposed peak rate runoff facility, therefore it will be designed to capture the flowrate generated by the existing 2-year, 24-hour design storm The swale is also capable of conveying the maximum flows generated for the developed conditions within the velocity parameters specified in the S WDM. The swale is proposed to be a grass-lined, trapezoidal channel with a 5-foot bottom width and 3:1 sideslopes. Preliminary biofiltration calculations were completed under the assumption that that a 200 if swale will be achievable with future construction. Biofiltration swale data is as follows: => 2-year, 24 Hour Storm flowrate: =0.17 cfs • Design Swale(2-year, 24-hour design storm): • Length=200 feet • Width=3.0 feet • Slope=2.00% • "n"Value=0.35 Peterson Consulting Engineers Page 6 DADATA\PR0JECTS\TREC0003\1REE.D0C NE Und S t `s � ..... t C� P. s c o. CL TY �F RETON _ PROPOSED t OPOS D SITE r 61, z; SURFACE WATER ............... aS�...... DRAINAGE SYSTEM t71i 0 s t W a = E ........ Z.. �.�...:....._. LEGEND N N- •tJ i _ a Oth-•St 4s- o W ' e� ra,.,4, 2. o C ...............::...w,.«w............... T NE 20th St �t z � ) �, L .. i STORM SEWER LDS s f '•,� `'l, D1TCH LINES ~� ' 4K-t NE 19th St ,. ",:;f,s :•�'` o BASKS CATCH .................. . ....v.......... :.- -..-.- - M, W O MANHOLES -IVLLS NE 18th St a zi ' : - i 4K- .. €....:v.�.........-.._.�..,,,,` � D�tECTION ARROWS f ............ .. i , .............,-.,.....a.....-n.. ... ...._ ........_ 6 _ .. f : f a +� >' , s f 6 •may ... a xt -� N�u c /4K-2 Yt 4Ci 6-J N-• - o w.... 9F6 ``"".'�../0 '---� CULVERT CROSJA\V' fi.C6 BL6 2 -( i 17gI-•: - , 4E6+21 ?Z. .......... '�,••.., in -. 7_11.. 4c6-6;d' { .kw---^•,- Z,ti,4 aK-1 6-- E - o ————_. REMON CITY LIMITS __..:.. .l. 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THE CITY OF RENTON �•.•••:a•-i : L•} ..Y ........f OMISSIONS. VHEN THIS t v.,l[- f�. ....... t'... IN NOT INFORMATION IS ULECFOR ERRORS PURPOSES DESIGNERS t ...........? i : , 7C..• f .' -: : :...i �f TION I U E FOR ENGINEERING 1,Z ARE TO FIELD VEf.I THIS INFORMATION. _ E,: > # ; y i - i.. T- • t. Y 2 1 i ++ i u ..... • CI i ° 4DB-2 4N-1 4CF. 4CD-)` `J ) 6' r a 1� �....,..Hk ._ ..} ...... Doe 1" „:„ .�.., ,�.. N,. .............. ....:...............,,,..,M..,,.-.:...r.,...........,,..:.:,...v,....... ....,...,..,�...CZ- .IDZ- - 1Lz I. 0 .. ........... a 1 Iz�!t3............t IIEz-7 2 , IlE2-6 1 :4800 `.+ .. `y : u2 jjjj liE2 10. • ^•w�., - t !•'-. IJ.CE-?" f..'lu2- 1 £ 2..... i Ey > ... ... } ...t i Ilt)1 .,....-..V..,...,.......,•..-..,..�,,...........,,..•.,....£ •�J 11C2-. �• .. .� ��. 1 £.. NE I I th PI - Itu 6 �� t tx.z J w ;' .112J_4 I D2 iu I A ♦ P/B/pa ,.ECHNICAL SERVICES >, > ...._ f x NE 11th St ff { O £ c of f I iiEJ z t �Nz 530 SW 1/4 tt 5309 NW 1/4 — — APPENDIX I HYDROLOGIC PARAMETERS AND CALCULATIONS DRAINAGE CALCULATION INFORMATION Precipitation Site runoff, infiltration and water quality treatment rates were calculated using WaterWorks software with the SCS Type 1-A, 24-hour storm event. Precipitation was determined from the King County SWDM Manual Isopluvial Maps for the 2, 10 and 100-year, 24-hour storm events. Precipitation rates are: • 2 Year, 24 Hour Storm: 1.95 inches • 10 Year, 24 Hour Storm: 2.85 inches • 100 Year, 24 Hour Storm 3.85 inches Soil Class Based on a detailed onsite soils analysis completed by Terra Associates, the majority of the site contains Alderwood soils. This soil type is considered hydrologic soil class "C per the S WDM. Curve Numbers The pre and post-development flow rates for the Kirkland Court site were calculated to determine the required onsite detention. Runoff for the pre-developed site is based on approximately 2.73 acres of heavily wooded area and the developed site is based on 0.46 acres of pavement and 2.27 acres of residential lots (calculated as 48% impervious). Curve number values for the pre and post-development calculations are: Pre-Developed Condition • Pervious(heavily wooded) 2.73 acres @ CN= 81 Post-Developed Condition • Impervious(Pvmt): 0.46 acres @ CN=98 • Pervious: 1.18 acres @ CN= 86 • Impervious (roofs and driveways) 1.09 acres @ CN=98 9/5/97 3 : 40 : 49 pm Peterson Engineering Consulting page 1 KIRKLAND COURT HYDROLOGIC CALCULATIONS 2, 10 AND 100-YEAR, 24-HOUR STORM EVENTS BASIN SUMMARY BASIN ID: D-002 NAME: Developed 2 Yr Storm SCS METHODOLOGY TOTAL AREA. . . . . . . : 2 . 73 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 1 .95 inches AREA. . : 1 . 18 Acres 1 .55 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 98 . 00 TC. . . . . 16 .56 min 1 . 75 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 1 . 95 s : 0 . 0100 impTcReach - Sheet L: 20 . 00 ns : 0 . 0110 p2yr: 1 . 95 s : 0 . 1000 impTcReach - Shallow L: 350 . 00 ks :27 . 00 s : 0 . 0200 PEAK RATE : 0 . 83 cfs VOL: 0 .29 Ac-ft TIME: 510 min BASIN ID: D-010 NAME: Developed 10 Yr Storm SCS METHODOLOGY TOTAL AREA. . . . . . . : 2 . 73 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2 . 85 inches AREA. . : 1 .18 Acres 1 .55 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 98 . 00 TC. . . . . 16 .56 min 1 . 75 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 1. 95 s : 0 . 0100 impTcReach - Sheet L: 20 . 00 ns : 0 . 0110 p2yr: 1 . 95 s : 0 . 1000 impTcReach - Shallow L: 350 . 00 ks :27 . 00 s : 0 . 0200 PEAK RATE: 1 .37 cfs VOL: 0 .47 Ac-ft TIME: 510 min BASIN ID: D-0100 NAME: Developed 100 Yr Storm SCS METHODOLOGY TOTAL AREA. . . . . . . : 2 .73 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 .85 inches AREA. . : 1 . 18 Acres 1 .55 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 98 . 00 TC. . . . . 16 . 56 min 1 . 75 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 1 . 95 s : 0 . 0100 impTcReach - Sheet L: 20 . 00 ns : 0 . 0110 p2yr: 1 . 95 s : 0 . 1000 impTcReach - Shallow L: 350 . 00 ks : 27 . 00 s : 0 . 0200 PEAK RATE: 1 . 98 cfs VOL: 0 . 68 Ac-ft TIME : 510 min 9/5/97 3 : 40 :49 pm Peterson Engineering Consulting page 2 HYDROLOGIC CALCULATIONS KIRKLA ND COURT 2, 10 AND 100-YEAR, 24-HOUR STORM EVENTS ----------------------- BASIN SUMMARY BASIN ID: E-002 NAME: Existing 2 Yr Storm SCS METHODOLOGY TOTAL AREA. . . . . . . : 2 . 73 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 1 . 95 inches AREA. . : 2 . 73 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 0 . 00 ABSTRACTION COEFF: 0 . 20 TC. . . . : 46 . 64 min 0 . 00 min TcReach - Sheet L: 100 . 00 ns : 0 .4000 p2yr: 1 . 95 s : 0 . 0100 TcReach - Channel L: 120 . 00 kc:5 . 00 s : 0 . 0258 TcReach - Shallow L: 200 . 00 ks:3 . 00 s : 0 . 0200 PEAK RATE: 0 . 17 cfs VOL: 0.13 Ac-ft TIME: 530 min BASIN ID: E-010 NAME: Existing 10 Yr Storm SCS METHODOLOGY TOTAL AREA. . . . . . . : 2 . 73 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 85 inches AREA. . : 2 . 73 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81. 00 0 . 00 ABSTRACTION COEFF: 0 .20 TC. . . . : 46 . 64 min 0 . 00 min TcReach - Sheet L: 100 . 00 ns : 0 .4000 p2yr: 1 .95 s : 0 . 0100 TcReach - Channel L: 120 . 00 kc:5 . 00 S : 0 . 0258 TcReach - Shallow L: 200 . 00 ks :3 . 00 S : 0 . 0200 PEAK RATE: 0 .49 cfs VOL: 0 .26 Ac-ft TIME: 530 min BASIN ID: E-100 NAME: Existing 100 Yr Storm SCS METHODOLOGY TOTAL AREA. . . . . . . : 2 . 73 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 . 85 inches AREA. . : 2 . 73 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 0 . 00 ABSTRACTION COEFF: 0 . 20 TC. . . . : 46 . 64 min 0 . 00 min TcReach - Sheet L: 100 . 00 ns : 0 .4000 p2yr: 1 . 95 s : 0 . 0100 TcReach - Channel L: 120 . 00 kc :5 . 00 s : 0 . 0258 TcReach - Shallow L: 200 . 00 ks :3 . 00 S : 0 . 0200 PEAK RATE: 0 . 90 cfs VOL: 0 .44 Ac-ft TIME: 520 min 9/5/97 3 :40 :49 pm Peterson Engineering Consulting page 3 KIRKLAND COURT HYDROLOGIC CALCULATIONS 2, 10 AND 100-YEAR, 24-HOUR STORM EVENTS --------------------------- HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf\AcFt Acres ------------------ 1 0 . 174 530 5454 cf 2 .73 2 0 .487 530 11452 cf 2 . 73 3 0 . 902 520 19098 cf 2 . 73 4 0 . 828 510 12763 cf 2 .73 5 1 .365 510 20650 cf 2 .73 6 1 . 985 510 29735 cf 2 .73 7 0 . 174 740 12763 cf 2 . 73 8 0 .487 580 20650 cf 2 . 73 9 0 . 903 550 29735 cf 2 . 73 APPENDIX II DETENTION CALCULATIONS 9/5/97 3 :40 : 51 pm Peterson Engineering Consulting page 6 KIRKLAND COURT HYDROLOGIC CALCULATIONS 2, 10 AND 100-YEAR, 24-HOUR STORM EVENTS -------------------------- LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE <--------DESCRIPTION---------> (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) 2-yr release ................. 0.17 0.83 Vaultl Orificel 104.91 7 3679.35 cf 10-yr release ............ .... 0.49 1.37 Vaultl Orificel 106.86 8 5142.81 cf 100-year release ........... .. 0.90 1.98 Vaulti Orificel 109.11 9 6830.50 cf 9/5/97 3 : 40 :49 pm Peterson Engineering Consulting page 5 KIRKLAND COURT HYDROLOGIC CALCULATIONS 2, 10 AND 100-YEAR, 24-HOUR STORM EVENTS --------------------------- DISCHARGE STRUCTURE LIST MULTIPLE ORIFICE ID No. Orificel Description: Vaultl outlet Outlet Elev: 100 . 00 Elev: 98 . 00 ft Orifice Diameter: 1 . 7036 in. Elev: 105 . 00 ft Orifice 2 Diameter: 2 .7539 in. Elev: 107 . 00 ft Orifice 3 Diameter: 2 .5078 in. 9/5/97 3 : 40 :49 pm Peterson Engineering Consulting page 4 KIRKLAND COURT HYDROLOGIC CALCULATIONS 2 , 10 AND 100-YEAR, 24-HOUR STORM EVENTS ------------------------------- STORAGE STRUCTURE LIST RECTANGULAR VAULT ID No. Vaultl Description: Storage Vault Length: 50 . 00 ft . Width: 15 . 00 ft . voids : 1 . 000 APPENDIX III BIOFILTRATION SWALE CALCULATIONS 9/9/97 1 :42 : 11 pm Peterson Engineering Consulting page 1 KIRKLAND COURT BIOFILTRATION SWALE CALCULATIONS EXISTING 2-YEAR, 24-HOUR STORM EVENT -------------------- REACH SUMMARY DITCH REACH ID No. BIO1 Ditch Length: 200 . 00 ft Ditch Width: 3 . 00 ft Side Slopes : 3 . 00 Ditch Slope: 0 . 0200 ft/ft Side Slope2 : 3 . 00 Contrib Bas : Mannings n : 0 . 3500 Dn Invert 100 . 00 ft Dn W.S . Elev: 100 . 2500 NUM Steps : 10 Trib Area: 2 . 73 Ac. Design Flow 0 . 17 cfs Depth 0 . 23 ft Vel 0 . 20 fps Upstream W. S . Elev: 0 . 00 ft . 9/9/97 1 :41 : 51 pm Peterson Engineering Consulting page 1 KIRKLAND COURT BIOFILTRATION SWALE CALCULATIONS EXISTING 100-YEAR, 24-HOUR STORM EVENT -------------- REACH SUMMARY DITCH REACH ID No . BIO2 Ditch Length: 200 . 00 ft Ditch Width: 3 . 00 ft Side Slopel 3 . 00 Ditch Slope: 0 . 0200 ft/ft Side Slope2 3 . 00 Contrib Bas : Mannings n : 0 . 0270 Dn Invert 100 . 00 ft Dn W.S . Elev: 100 . 1000 Num Steps : 10 Trib Area: 2 . 73 Ac. Design Flow 0 . 89 cfs Depth 0 . 14 ft Vel 1 . 91 fps Upstream W. S . Elev: 0 . 00 ft . 0^70CI7 osooCIO NNNNNN 2�iltL fi!W W W W W A V-o V&i =WWwjj R NCI r/=lWW m K�2 K�Aiv] Coo 2-f- Ilk 24 2Zq Sc 22 +�l S+- dak may Z91 19 9 I / { u2KLJW-b COURT Or J i rul(l suI i 4r- d �xna C e /s o n 16 r s) ux.S aQa«R Co��a Dept VI0A s, s dam . AIAI �33 wee Pa d1 wur V 0 a •_� 'sr5v AN 12Q2S-� ��I�rsOn (�%c� ✓�rf-9 otzF � � , ( �r�ov ✓ j Dr*L � �Pcv Vol u� 0 v ( f- lieu �. lg 1 39 83. 3 ►o? 15250 Z J 2(ter.F2 117 5 • AA OrLf< <e d t ai'VA vr► Sa� ,m "MR, o z 2. vo i i i i i i i i i