The URL can be used to link to this page

Home My WebLink AboutSWP272332(3) STORM DRAINAG E REPORT FOR CURTIS H, LLC LOT 1 OF WASHINGTON TECHNICAL CENTER LOCATED AT SOUTHWEST 7TH STREET NEAR POWELL AVENUE RENTON, WASHINGTON •� FOR SGA CORPORATION BY 0 JOHN E. ANDERSON, P.E. BUSH, ROED & HITCHINGS, INC. 2009 MINOR AVENUE EAST SEATTLE, WA 98102 (206) 323-4144 BRH JOB NO. 97102.00 DATE July 15, 1997 0 S�g�C► v�' s`pI�SAL E -7 /b/9' EXPIRES 1 //12 1cr7 Li • AD � M ((2 ELsna,tl os wu ,rm s tn.x) 6 9' u m OCCUCVK OtlP. QE — st rEwrsE R=}69J 4' I I vMaE m¢:Vmo .M2:�iuco L=128.7T cvsZilw�oml &=18' 29' 52" L=1 15.44'±_ N 88' 42 E 100 ' rw KCVSTOMF w�Ll P / '+ � Doer H oaons I I I // II / ' SLOTTED OHNN-E �0 II ,DC ,C",60 TE-t9.0 I I N / ryb j y ! / PROPOSED BUILDING O / •� F.F.- 22.0 / h niv I I o Q � ,aw 10 �1 Te ti t7 •0!; I 3IR 10 N 88' 15 00 W" 50 _5.27 '------------ LL S.W. 7th ST. .. j v W N H 0 M E H �y S C r F 60 UNITS 4 �' v.(l`/16 K J ` b ASE ! r/ 7a�s 385• :,.% r� j x . ST/�qU ,fie �ti 's 6, U T J +i C 4 1.114 ° i1/4 3 b N 13, J 3 C A , B N T. 5 Ac. �4 A NO 60 s aric iry E'.SrMLN7' zM Bl /3 12` ` 'o is. r.L.36 9 6 7 6 ,.i ( G ov t Lo — — �r — -1. — — 30.10 46 C A L I ;C E E R l _ 4 - 12rt�r. I GEO A� HORMEL 8 0. 7 Sri f uric it �y�- I , p A R K / CENTRAL. ' 3 2 / 5GA SITE E I'. 2.18A PU6ET INC. Q f $ r.L.27o — _ g O —Et— 37-77 5 01 Ao. �a- .1"I�Ar+• _, rnrZ�t »wir ta�rJ W �, vric.ry— .wcK •.i�wrrvs _i �� F1.25447 4 — eO 335E LAS OF TTLE ` TLAS OF SEATTLE RIGHTED & PUBLISHED BY tent COPYRIGHTED & PUBLISHED BY y,ta1 KROLL MA OMPANY, INC., SEATT KROLL MAP COMPANY, INC., SEATTLE SCALE ET SCALE i INCH 200 FEET Itl_zoo� 0 TABLE OF CONTENTS I. Project Overview II. Preliminary Conditions Summary III. Core and Special Requirements IV. Detention Analysis V. Water Quality Design VI. Level I Analysis VII. Pipe Sizing Calculations VIII. Erosion Control • • I. PROJECT OVERVIEW SGA is proposing to build a 34,585 square foot officelwarehouse building on Parcel A of Washington Technical Center. The total site is 2.88 acres in size. Rail road track are located on the northern and eastern boundaries. The tracks are located within easements recorded with the plat. Southwest 7th Street is the southern boundary of the site. Grades on the site vary from elevation 20 in the northeastern corner to elevation 16 in the southwestern corner. The ground slopes within the property are between 1 and 2 percent. Ground cover consists of blackberry bushes and grasses. The proposed building would be dock high. Truck loading docks would be located on the north side of the building. The building finish floor elevation would be approximately 2.5 feet above the existing ground elevation. There will be approximately 1.3 acres of asphalt paving around the building for vehicle parking lot and truck maneuvering areas. Storm water runoff from the asphalt pavement will be conveyed to a combine wetpond/detention pond located at the southwest corner of the site. The wetpond is oversize so biofiltration swales are not required. Filter strips will be used for water quality improvements for the parking area along Southwest 7th Street. This area will have the most vehicle traffic and the filter strips will provide additional water treatment. • Construction of an office/warehouse building on this site is consistent with surrounding developments. Utilities within Southwest 7th Street have been sized for this type of development. There is adequate depth for gravity storm water and sanitary sewer connections. According to City records, a 10-inch water main is stubbed to the southeast corner and a 12-inch water main is located within Southwest 7th Street. Therefore, the development of this property does not present any significant design problems. • • H. PRELIMINARY CONDITIONS SUMMARY The 2.88 acre site is covered with blackberry bushes and grasses. Existing ground slopes from west to east at slopes between 1 and 2 percent. A 60-inch storm drainage pipe is located in Southwest 7th Street. According to the City, storm water runoff from the developed site can be discharge to the 60-inch pipe. Storm water detention is required prior to discharge from the site. The detention pond will be sized using the King County Design Manual Method as adopted by city of Renton. No offsite areas contribute to the storm water flows. An existing CN value of 82 will be used to calculate the pre-developed storm water peak flows. i M. CORE AND SPECIAL REQUIREMENTS CORE REQUIREMENT#1: Storm water will be discharged to the existing 60-inch storm drainage pipe located in Southwest 7th Street. The pipe design included this property in the tributary area. This is the City's recommended storm drainage connection. Therefore Core Requirement #1 is met. CORE REQUIREMENT #2 The railroad tracks and Southwest 7th Street grades prevent offsite storm water from entering the site. Therefore, no upstream basin analysis is required for this property. Storm water discharged from the site will be conveyed by 60-inch storm pipes in Southwest 7th Street. The 60-inch pipe flows west to Naches Avenue. The storm water then flows north in Naches where it is discharged into a regional storm water mitigation area. The existing conveyance system was design to convey storm water discharged from the site. Original sizing for the pipe used the Rational Method of analysis. Current design standards use the hydrograph method that lowers peak rate discharge from that calculated by the Rational Method. Therefore, the downstream system has • adequate capacity for the proposed development. CORE REQUIREMENT#3 Peak rate control will be provided for the storm water runoff. A storm water detention system will be located in the southwest corner of the site. Developed storm water peak rate discharges from the site will be limited to the 2 year, 10 year and 100 year pre-developed values. Storm water detention facility calculations are included in the report. The City allows over-sizing the wetpond for mitigation of the biofiltration swale requirements. The required wetpond volume is 3,955 cubic feet. The volume provided is 11,742 cubic feet. The proposed wetpond also provides nearly 3 times the required surface area. Therefore, biofiltration swales are not required. Wetpond sizing calculations are included in the report. CORE REQUIREMENT#4 Detailed pipe sizing calculations are provided. The calculations show there is more than adequate conveyance capacity for the 100 year storm water peak flows. • • CORE REQUIREMENT#5 A detailed erosion/sedimentation control plan has been prepared for the site grading. The storm water detention pond will be used for a settling basin during construction. According to the design standards, a sediment trap would meet the requirements for this site. Using the detention pond provides significantly more sediment volume and surface area than required. Since the pond is oversized for the developed conditions, it will more than adequate for controlling run off during the site grading phase. Interceptor swales and filter fabric fence will be installed at the limits of clearing. Rock check dams will be installed in the interceptor ditches. Rock construction entrances will be installed at the proposed driveway locations. SPECIAL REQUIREMENTS SECTION 1.3 The only Special Requirement that applies to this project is 1.3.5. A wetpond is required because the development will have 1.3 acres of imperious surface area subject to vehicular use. A wetpond will be constructed in the storm water detention pond area. According to the manual, the wetpond must provide the PT-WQ Storm volume and have a surface area equal to 1% of the impervious surface area. The proposed detention/wetpond design exceeds both of these conditions. • • • IV. DETENTION ANALYSIS i i • a BUSH, ROED& HITCHINGS, INC. JOB S(23 b" CIVIL ENGINEERS& LAND SURVEYORS 2009 Minor Avenue East SHEET NO. OF Seattle, WA 98102 CALCULATED BY DATE —7/ 1 Z / _7 �r (206)323-4144 FAX(206)323-7135 6 H 1-800-935-0508 CHECKED BY DATE SCALE �T3Rr- 1D[TCN37101J1\,j�TPo► ►D . P�PP2oV�tr L _. vt4Zlfi►•l .. OF "QETE.►`►Tt_prJ T�o,�� was: Movc�� UP __ Z__FC`ET. Ti-r�S ..�t►4S Do► IE Tb RtDUC�E_ -�'t-k� __.._c�-+-a.r.�GE o s-ro_P, w p,-rETZ f3ac K 1► �.40 1 k4 TO 7+4-t✓ rKon�t Cc,p" P)tt Stair . s-r2tT. . O� . �-rE-j Tt p N. i. 15_ . (JdtaJ 5ET_. p�T . ..P�PPfLOK.t_vv��►.TL`-L: Y . T -rtiP cs r ......`r'17 A � KFL.o �t- p _I LL : AL'40 BE ...l t►..�:$7 A.LLiE p O I•.1. '[ C�uT[--�T P�P ? T t-+E ...-C'o Z .� ..t '�► TM�s' p,Ll,o'ivs T ►4t- . PC4.orvC� [' \AJ.E T�2t.1 ._EtD (-=E . OF *FPZXt K-A-0 4�GiZEp•SES T1-�� ___ • VtlS'rA0►J D 1/DL..0 ME, PROV Iti;)E17 612I(01 C F To \AJ PST tZ. C2,v A-1 U �,� VOL-U KAE _R QU t 2E h .. FoR T1- e S_�-t� _ t�_ -3 _9S5 GF" , Tfe . hlE DEs t ZCr/19 ES_ ' _►9"l: . -["( rs . . M U R,E 1+�/AT�`12 t T(+?a►J EQl1 QED RED .4,Sg -T'1 tvt ES TVA-Ac TZ�QUtg2c� 5 2 w�c�E P 1p. , ..T c�E DR , Bl o t L7't'2-N-TLOl'.A_ 6w_NuE PROD JCT204 1(&nqk Sheets)205 1 iPadaeai®®)n<.Groton.Mass.01471.To Order PHONE TOLL FREE 1A00.225 6380 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL _1 FIGURE 3.5-2A HYDROLOGIC SOIL GROUP OF THE SOILS IN KING COUNTY: HYDROLOGIC HYDROLOGIC SOIL GROUP GROUP' SOIL GROUP GROUP* Akferwood C Orcas Peat D Arents,Alderwood Material C Oridia D Arents..Everett Material B Ovail C Beaushe C PBchuck C Bellingham D Puget D Briscot D Puyallup B Buckley D Ragnar B Coastal Beaches Variable Renton D Earimont Silt Loam D Riverwash Variable Edgewick C Sala] C Everett A Sammamish D Indianola A Seattle D Xhsap C Shacar D Kaus C S]Silt C Mixed Alluvial Land Variable Snohomish D Nedton A Sultan C Newberg B Tukwila D Nooksack C Urban VarlableAdko Normal Sandy Loam D Woodinville D HYDROLOGIC SOIL GROUP CLASSIFICATIONS A. (Low runoff potential). Sods having high Infiltration rates, even when thoroughly wetted,and consisting chiefly-of deep,well-to-excessively drained sands or gravels. These sods have a high rate of water transmission. S. (Moderately low runoff potential). Sods having moderate Infiltration rates when thoroughly wetted,and consisting chiefly of moderately fine to moderately coarse textures. These sods have a moderate rate of water transmission.- C. (Moderately high runoff potentia(1. Sods having slow infiltration rates when thoroughly wetted, and consisting chiefly of sods with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. These sops have a slow rate of water transmission. D. (High runoff potential). Sods having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay sods with a high swelling potential, sods with a permanent high water table, soils with a hardpan or day layer at or near the surface,and shallow soils over nearly Impervious material. These sods have a very slow rate of water transmission. • From SCS,TR-55, Second Edition, June 1986. Exhibit A-1. RevWons made from SCS, Sol Interpretation Record. Form 05, September 19M 3.5.2-2 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL _TABLE 3.526 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 duralkx-L CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A B C D Cultivated land(1): winter condition 86 1 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 Ord: 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 Unit/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 DU/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 DU/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 root and driveway runoff Is directed Into street/storm system. (3) The remaining pervious areas (lawn) are considered to be In good condition for these curve numbers. 3.5.2-3 1190 i._ ,:. ate► �.� � � '•a'i �f LIN _ � �1�1��' ,�, ;•��:;��.�i\Ate,\�� t -� � . h f • • t • • lid - ,i ► �, , �.,err �.�il ,��!• � �� w sS errs= 1i:��,� 1-�� ►i,,� , '+� �.: .. `�: WAS WIS NEW -� � 17 Ell: ~ram �. !!�� ► ; Wr • • MR I►1 , 1A Fri. lot Wag ARV �� r. `., � rid�,�,; •� � . /�`�•- .. war `1�� t•�u _,� 7/15/97 11 :38 : 9 pm Bush, Roed & Hitchings, Inc page 1 SGA SITE AT WASHINGTON TECH CENTER JOHN E . ANDERSON, P.E. PROJECT NO. 97102 -------------------- BASIN SUMMARY BASIN ID: Bl NAME : 2 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 88 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 2 . 88 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 00 0 . 00 ABSTRACTION COEFF: 0 .20 TC. . . . : 18 . 00 min 0 . 00 min PEAK RATE: 0 . 29 cfs VOL: 0 . 16 Ac-ft TIME : 480 min BASIN ID: B2 NAME: 10 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 88 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 2 . 90 inches AREA. . : 2 . 88 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 00 0 . 00 ABSTRACTION COEFF: 0 . 20 TC. . . . : 18 . 00 min 0 . 00 min PEAK RATE: 0 . 72 cfs VOL : 0 . 31 Ac-ft TIME: 480 min BASIN ID: B3 NAME: 100 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 88 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 2 . 88 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 00 0 . 00 ABSTRACTION COEFF: 0 . 20 TC. . . . : 18 . 00 min 0 . 00 min PEAK RATE: 1 . 27 cfs VOL: 0 . 51 Ac-ft TIME: 480 min BASIN ID: B4 NAME: 2 YEAR DEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 88 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 60 Acres 2 .28 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 00 98 . 00 ABSTRACTION COEFF: 0 . 20 TC. . . . : 12 . 00 min 12 . 00 min PEAK RATE: 1 . 07 cfs VOL: 0 .37 Ac-ft TIME: 480 min 7/15/97 11 : 38 : 13 pm Bush, Roed & Hitchings, Inc page 2 SGA SITE AT WASHINGTON TECH CENTER JOHN E. ANDERSON, P.E. • PROJECT NO. 97102 ---------------------- BASIN SUMMARY BASIN ID: B5 NAME: 10 YEAR DEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 88 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 . 60 Acres 2 .28 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 00 98 . 00 ABSTRACTION COEFF: 0 . 20 TC. . . . : 12 . 00 min 12 . 00 min PEAK RATE: 1 . 66 cfs VOL: 0 . 57 Ac-ft TIME: 480 min BASIN ID: B6 NAME: 100 YEAR DEVELOPED SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 88 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 60 Acres 2 . 28 Acres TIME INTERVAL. . . . : 10 .00 min CN. . . . : 82 . 00 98 . 00 ABSTRACTION COEFF: 0 . 20 TC. . . . : 12 . 00 min 12 . 00 min PEAK RATE: 2 . 32 cfs VOL: 0 . 80 Ac-ft TIME: 480 min i 7/15/97 11 :32 :36 pm Bush, Roed & Hitchings, Inc page 3 SGA SITE AT WASHINGTON TECH CENTER JOHN E. ANDERSON, P.E . • PROJECT NO. 97102 ---------------------- HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf\AcFt Acres ------------------------ 11 0 . 293 550 16098 cf 2 . 88 2 `c2 Po►Jc� fZEt.Et�SE 12 0 . 696 530 24920 cf 2 . 88 to `(E-� 'Fo,.ap F.tLET,,vSE 13 0 . 968 530 34948 cf 2 . 88 Z n . Z-1 LP75 ( V U K,(2 n) ,-7Z Lr5 (�z- 7z1 GF5 s Eta Y P.¢rv. /S.►k 0,I! Vo L.0 hn E 14.00 4560.69 0.00 0.00 0.00 16.00 6378.26 2.00 10888.26 10888.26 18.00 7849.51 2.00 14202.35 25090.61 0.00 25090.61 l�l oTE ; N.2c S b lO 1 T i E b 2 P, • 7/15/97 11 : 32 :38 pm Bush, Roed & Hitchings, Inc page 4 SGA SITE AT WASHINGTON TECH CENTER JOHN E. ANDERSON, P.E. • PROJECT NO. 97102 ------------------------------ STAGE STORAGE TABLE CUSTOM STORAGE ID No. 1 Description: DETENTION POND BETWEEN 14 & 18 STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- 14.00 0.0000 0.0000 15.10 6016 0.1381 16.20 12362 0.2838 17.30 20187 0.4634 14.10 546.95 0.0126 15.20 6563 0.1507 16.30 13073 0.3001 17.40 20898 0.4798 14.20 1094 0.0251 15.30 7110 0.1632 16.40 13785 0.3164 17.50 21610 0.4961 14.30 1641 0.0377 15.40 7657 0.1758 16.50 14496 0.3328 17.60 22321 0.5124 14.40 2188 0.0502 15.50 8204 0.1883 16.60 15207 0.3491 17.70 23033 0.5288 14.50 2735 0.0628 15.60 8751 0.2009 16.70 15919 0.3654 17.80 23744 0.5451 14.60 3282 0.0753 15.70 9298 0.2135 16.80 16630 0.3818 17.90 24455 0.5614 14.70 3829 0.0879 15.80 9845 0.2260 16.90 17341 0.3981 18.00 25167 0.5777 14.80 4376 0.1004 15.90 10392 0.2386 17.00 18053 0.4144 14.90 4923 0.1130 16.00 10939 0.2511 17.10 18764 0.4308 15.00 5469 0.1256 16.10 11650 0.2675 17.20 19476 0.4471 7/15/97 11 : 32 :39 pm Bush, Roed & Hitchings, Inc page 5 SGA SITE AT WASHINGTON TECH CENTER JOHN E. ANDERSON, P.E. • PROJECT NO. 97102 ------------------ DISCHARGE STRUCTURE LIST MULTIPLE ORIFICE ID No. 1 Description: MULTIPLE ORIFICE Outlet Elev: 14 . 00 Elev: 14 . 00 ft Orifice Diameter: 3 . 6750 in. Elev: 14 . 70 ft Orifice 2 Diameter: 5 . 0000 in. • • 1 1 7/15/97 11 :32 :50 pm Bush, Roed & Hitchings, Inc page 6 SGA SITE AT WASHINGTON TECH CENTER JOHN E . ANDERSON, P.E. PROJECT NO. 97102 --------------------- LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAR-> OUTFLOW STORAGE <--------DESCRIPTION---------> (cfs) (Cfs) --id- --id- <-STAGE> id (Cfs) VOL (cf) ----------------------------------------------------------- 2 YEAR STORM ................. 0.29 1.07 1 1 14.64 11 0.29 3503.44 Cf 10 YEAR STORM ................ 0.72 1.66 1 1 14.95 12 0.70 5207.77 Cf 100 YEAR STORM ............... 1.27 2.32 1 1 15.34 13 0.97 7346.87 Cf • V. WATER QUALITY DESIGN • 7/15/97 11 :42 :45 pm Bush, Roed & Hitchings, Inc page 1 SGA SITE AT WASHINGTON TECH CENTER JOHN E . ANDERSON, P.E . • PROJECT NO. 97102 -------------- DETAIL BASIN SUMMARY BASIN ID: B7 NAME : WATER QUALITY STORM PT-WQ SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 88 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 0 . 67 inches AREA. . : 0 . 60 Acres 2 . 28 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 .00 98 . 00 TC. . . . . 12 .00 min 12 . 00 min ABSTRACTION COEFF: 0 . PEAK RATE: 0 .27 cfs VOL: 0 . 09 Ac-ft TIME: 480 min TIME DESIGN TIME DESIGN TIME DESIGN TIME DESIGN TIME DESIGN TIME DESIGN RUNOFF RUNOFF RUNOFF RUNOFF RUNOFF RUNOFF (min) (cfs) (min) (cfs) (min) (cfs) (min) (cfs) (min) (cfs) (min) (cfs) --------------------------------------------------------- 10 310 0.0318 610 0.0699 910 0.0436 1210 0.0357 1510 0.0001 20 320 0.0338 620 0.0701 920 0.0432 1220 0.0357 1520 30 330 0.0355 630 0.0704 930 0.0431 1230 0.0357 1530 40 340 0.0371 640 0.0706 940 0.0431 1240 0.0358 1540 50 350 0.0405 650 0.0670 950 0.0432 1250 0.0358 1550 60 360 0.0447 660 0.0618 960 0.0432 1260 0.0358 1560 . 70 370 0.0474 670 0.0598 970 0.0433 1270 0.0359 1570 80 380 0.0494 680 0.0590 980 0.0434 1280 0.0359 1580 90 390 0.0511 690 0.0588 990 0.0434 1290 0.0360 1590 100 400 0.0526 700 0.0587 1000 0.0435 1300 0.0360 1600 110 410 0.0608 710 0.0588 1010 0.0410 1310 0.0360 1610 120 420 0.0720 720 0.0589 1020 0.0374 1320 0.0361 1620 130 430 0.0779 730 0.0591 1030 0.0360 1330 0.0361 1630 140 440 0.0903 740 0.0593 1040 0.0354 1340 0.0361 1640 150 0.0001 450 0.1056 750 0.0595 1050 0.0352 1350 0.0362 1650 160 0.0008 460 0.1461 760 0.0597 1060 0.0351 1360 0.0362 1660 170 0.0021 470 0.2409 770 0.0562 1070 0.0351 1370 0.0362 1670 180 0.0039 480 0.2706 780 0.0511 1080 0.0352 1380 0.0363 1680 190 0.0057 490 0.2095 790 0.0491 1090 0.0352 1390 0.0363 1690 200 0.0074 500 0.1557 800 0.0483 1100 0.0352 1400 0.0363 1700 210 0.0091 510 0.1239 810 0.0481 1110 0.0353 1410 0.0364 1710 220 0.0107 520 0.1113 820 0.0481 1120 0.0353 1420 0.0364 1720 230 0.0130 530 0.0961 830 0.0481 1130 0.0354 1430 0.0364 1730 240 0.0157 540 0.0796 840 0.0482 1140 0.0354 1440 0.0365 1740 250 0.0178 550 0.0730 850 0.0483 1150 0.0354 1450 0.0257 1750 260 0.0197 560 0.0705 860 0.0484 1160 0.0355 1460 0.0106 1760 270 0.0214 570 0.0696 870 0.0485 1170 0.0355 1470 0.0044 1770 280 0.0230 580 0.0694 880 0.0486 1180 0.0355 1480 0.0018 1780 290 0.0259 590 0.0695 890 0.0469 1190 0.0356 1490 0.0007 1790 300 0.0294 600 0.0697 900 0.0445 1200 0.0356 1500 0.0003 1800 j `�bLUIVIE ��QUII D = D� ogAr -ICT = 3� 9g0 G� EL6V AZC* L1p Ly VOWNME 10.00 1575.18 0.00 0.00 0.00 12.00 2868.01 2.00 4379.11 4379.11 • 14.00 4560.69 2.00 7363.56 11742.67 0.00 11742.67 �-- ToT p.�, w t'T�or.1 \/o L-v t-n E Cfircr!o DED P�PEP P1eoV b VOLUVAE FEQL,IeED Csee E3a.51N-� A��a Rccz�.) zed � �2,2gpc�43 C' 33 'FQ.C,tA R-raw ►.�, 5S t • VI. LEVEL I ANALYSIS Storm water will be discharged from the detention pond at the pre-developed peak flow rates to a 60-inch pipe located within Southwest 7th Street. From the connection point the storm water will be tight lined approximately 1,100 feet west to Naches Avenue. Storm water is then tight lined north approximately 650 feet in the Naches Avenue storm pipe. From the Naches storm system the storm water is discharged into an open conveyance ditch that flows west into a regional detention basin. • The tight line system and detention basin were sized using the Rational Design Method. Current City design standards for peak rate control are more restrictive than used to size the existing system. Therefore, development of this site will not adversely impact the existing storm system. VII. PIPE SIZING CALCULATIONS • • w 11 HIM .. tdf31{aSY3 — . _ r Sol ' ! I I ,oil I _ , i t Gat) na a QCj, 1— KTI�'/1 or, ox i( t 3S-2 Ool L o{ ter, VIM Sthl ll 8 �5go�b t dy u , � z ,. o%'oZ 31OZ j" 1 1 .3A % ——a+N31OW3 crr t � ' At ( � �u fw /J w, ww ao,L1 a1 77 OTVa S s� d` _ t 101 �h! /l et 077 STORM SEWER SUMMARY REPORT PAGE i OF 1 CURTIS II, LLC FILE: 97102.STM RAINFALL FILE: SEATTLE.RND 10 YEAR DESIGN STORM I = 13.080/ ( Tc + 5.000) ' 0.770 LINE ID I FLOW RATE INFO I PIPE INFO I HYDRAULIC INFO LINE#1 DESCRIPTION ZINC ARIRUNOFFCIINLTIMEIINLT IIINC CIA) INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL IHGLSLOPEIHYD GRD I VEL I DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIAI TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I (ac) I C I (min) I(in/h)1 (cfs) I (cfs) I (cfs) 1(in) I (ft) I(ft) 1(ft/ft)1 (ft/ft)1 (ft) I (ft/s) I I I I I I I I I I I I I I I 1 I OUTFALL-CB1 1 0.41 0.871 0.001 3.791 1.191 0.001 1 12DI 14.931 551 0.0121 0.0071 15.711 3.70 1 DNLN = 0 1 1.91 0.881 12.531 1.441 2.441 2.441 2.71 12D1 14.651 1 0.0051 1.00 1 15.311 4.42 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 CB1-CB4 1 0.11 0.901 0.001 3.791 0.311 0.001 1 12DI 15.381 901 0.0121 0.0011 16.001 2.36 1 DNLN = 1 1 0.91 0.861 11.761 1.491 1.211 1.211 2.71 12DI 14.931 1 0.0051 1.00 1 15.921 1.54 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 CB4-CB5 1 0.31 0.851 0.001 3.791 0.801 0.001 1 12DI 15.801 841 0.0121 0.0021 16.251 3.23 1 DNLN = 2 1 0.91 0.861 11.221 1.531 1.121 1.121 2.71 12DI 15.381 1 0.0051 1.00 1 16.081 1.88 I I I I I I I I I I I I I I I 4 1 CB5-CB6 I 0.21 0.851 0.001 3.791 0.711 0.001 1 12DI 16.471 1341 0.0121 0.0031 16.851 2.97 DNLN = 3 1 0.61 0.861 10.251 1.611 0.831 0.831 2.71 12DI 15.801 1 0.0051 1.00 1 16.411 1.64 I I I I I I I I I I I I I I I CB6-CB7 1 0.21 0.851 0.001 3.791 0.741 0.001 1 12DI 17.001 1081 0.0121 0.0031 17.321 2.61 DNLN = 4 1 0.41 0.871 9.341 1.681 0.561 0.561 2.71 12D1 16.471 1 0.0051 1.00 1 16.991 1.34 I I I I I I I I I I I I 1 1 6 1 CB7-CB8 1 0.21 0.901 8.301 1.781 0.241 0.001 1 12D1 17.441 871 0.0121 0.0031 17.711 2.04 DNLN = 5 1 0.21 0.901 8.301 1.781 0.241 0.241 2.71 12DI 17.001 1 0.0051 1.00 1 17.431 0.76 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 7 1 CBI-CB2 1 0.41 0.901 0.001 3.791 1.261 0.001 1 12DI 17.001 1751 0.0121 0.0091 17.421 3.10 1 DNLN = 1 1 0.61 0.901 9.461 1.671 0.951 0.951 4.21 12DI 14.921 1 0.0121 1.00 1 15.921 1.21 I I I I I I I I I I I I I I I 8 1 CB2-CB3 1 0.31 0.901 8.501 1.761 0.411 0.001 1 1201 17.471 931 0.0121 0.0031 17.831 2.33 1 DNLN = 7 1 0.31 0.901 8.501 1.761 0.411 0.411 2.71 12DI 17.001 1 0.0051 1.00 1 17.561 0.91 i • i 1 0�97 STORM SEWER SUMMARY REPORT PAGE 1 OF 1 CURTIS II, LLC FILE: 97102.STM RAINFALL FILE: SEATTLE.RND 100 YEAR DESIGN STORM I - 26.250/ ( Tc + 6.750) - 0.830 LINE ID I FLOW RATE INFO I PIPE INFO I HYDRAULIC INFO LINE#1 DESCRIPTION ZINC ARIRUNOFFCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL IHGLSLOPEIHYD GRD I VEL DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIAI TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I I (ac) I C I (min) 1(in/h)1 (cfs) I (cfs) I (cfs) 100 1 (ft) 1(ft) 1(ft/ft)1 (ft/ft)1 (ft) I (ft/s) I I I I I I I I I I I I I I I 1 I OUTFALL-CBI 1 0.41 0.871 0.001 5.381 1.691 0.001 1 12D1 14.931 551 0.0121 0.0121 16.111 4.85 1 DNLN = 0 1 1.91 0.881 12.521 2.251 3.811 3.811 2.71 12D1 14.651 1 0.0051 1.00 1 15.481 5.48 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 CBI-CB4 1 0.11 0.901 0.001 5.381 0.441 0.001 1 12D1 15.381 901 0.0121 0.0021 16.691 2.39 1 DNLN = 1 1 0.91 0.861 11.901 2.311 1.881 1.881 2.71 12DI 14.931 1 0.0051 1.00 1 16.481 2.39 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 CB4-CB5 1 0.31 0.851 0.001 5.381 1.141 0.001 1 12DI 15.801 841 0.0121 0.0021 16.951 2.21 I DNLN = 2 1 0.91 0.861 11.281 2.381 1.741 1.741 2.71 12D1 15.381 1 0.0051 1.00 1 16.781 2.21 1 I I I I I I I I I I I I I I 4 1 CB5-CB6 1 0.21 0.851 0.001 5.381 1.011 0.001 1 12D1 16.471 1341 0.0121 0.0011 17.181 2.18 DNLN = 3 1 0.61 0.861 10.101 2.521 1.301 1.301 2.71 12D1 15.801 1 0.0051 1.00 1 17.021 1.66 I I I I I I I I I I I i I I I A, CB7 I 0.21 0.851 0.001 5.381 1.051 0.001 1 12D1 17.001 1081 0.0121 0.0011 17.411 2.96 DNLN = 4 1 0.41 0.871 9.231 2.631 0.871 0.871 2.71 12D1 16.471 1 0.0051 1.00 1 17.251 1.31 I I i I I i I I I I I I I I I 6 I CB7-CB8 1 0.21 0.901 8.301 2.771 0.371 0.001 1 12D1 17.441 871 0.0121 0.0031 17.781 2.26 1 DNLN = 5 1 0.21 0.901 8.301 2.771 0.371 0.371 2.71 12D1 17.001 1 0.0051 1.00 1 17.541 0.87 I I I i I I I I I I I I I I I 7 1 CBI-CB2 1 0.41 0.901 0.001 5.381 1.791 0.001 1 12D1 17.001 1751 0.0121 0.0061 17.521 3.62 1 DNLN = 1 1 0.61 0.901 9.381 2.611 1.481 1.481 4.21 12D1 14.921 1 0.0121 1.00 1 16.481 1.89 I I I I I I I I I I I I I I I 8 I CB2-CB3 1 0.31 0.901 8.501 2.741 0.641 0.001 1 12D1 17.471 931 0.0121 0.0021 17.931 2.49 1 DNLN = 7 1 0.31 0.901 8.501 2.741 0.641 0.641 2.71 12D1 17.001 1 0.0051 1.00 1 17.721 1.06 • 0 PRE FILE Lirt� 1 �LJTFALL-�B1 22 [F1] 21 M enu Z 20 19 Natural ground slop e 1@ w 17 w 16 H(3L. slope 1. 151%a - 15 55 fi. of 12 in. pips (g) 0.5001,17.' 14 13 0 10 20 30 40 5D 60 STATI O N i • i PR[�FILE Line Z CB 1-CBA 22 Natural ground slope 21 Men 20 19 10 17 HOWL. slope 0.237,7.' 16 90 fl. of 12 in. pipe (a 0.500:4 15 14 13 0 20 40 60 80 STATI O N PP1, 01FILAE Line 3 CBA-CBS 22 [F1] 21 Menu Natural ground slope -1.52 a � 20 14 w 18 W17 HGL slope 0.200' 16 84 ft. of 12 in. pipe 0.5001;,.' 15 14 0 10 20 30 40 50 60 70 80 90 sTnvrr c)N PR.�FILE L.inie 4 CBS-CB6 � 21 [F1] Menu 20 Natural ground slope 0.00% 14 16 w134 ft. of 12 in. pipe (g) 0.500 17 w HGL slope 0.114?4 r 16 15 14 0 20 40 60 60 100 120 140 STATI�N PRE FILE Lines 5 CBS-�B7 21 [F1] Menu 20 Natural ground slope O.00�o ~ 19 108 ft. of 12 in. pipe O.5OO�o w 18 17 E iGL slope 0.143i'a 16 15 0 20 40 60 80 100 120 TATI(D N PRE FILE Line 6 CB7-cab 23 [F1] 22 Menu 21 Natural ground s]apo 2.30%' 20 E--� 19 w 87 ft. of 12 in. pipe (9) 0.500',Ixo' 18 HO3L. slojoe 17 16 0 10 20 30 40 50 60 70 80 90 STATI Q N PR�JFILE •••�••� Line 7 �B1-CB2 22 [F1] 21 Menu Natural gxounci slope -O.631a 20 19 w18 175 ft. of 12 in pipe Cg? 1. 190%, slope O.595�7b 16 15 14 13 0 20 40 60 00 100 120 140 160 180 SMAI- 3 N PR(�FIL,E Lines 8 CB2-CB3 22 [F11 Menu 21 O Natural ground Slope 1.02% w--a 20 w 19 93 ft. of 12 in. pipe i:�D 0.500� w is HGL Slope 0,220M 17 16 0 20 40 60 80 100 STP�TI�N VIII. EROSION CONTROL 1. The owner may decide to pre-load the building area. This will depend on the availability of material at the time of building permit submittal. Separate pre-load plans have been prepared in the event material can be obtained. The pre-load plan limits work area to the building pad, stock pile area, sediment trap and construction entrances. All other areas will be undisturbed. Pre-loading the building pad will not significantly change the existing storm run off pattern for the site. All storm water run off will be conveyed to the natural low point of the site. The duration of a pre-load should be approximately 2 to 3 months. 2. The ECP for the site utilizes the detention pond for peak rate and sediment control. The detention pond sizing calculations show the pond has more than adequate volume for the developed site conditions.. Since the pond meets the developed condition requirements, it will also exceed the requirements for the grading phase. Storm water will be conveyed to the detention pond using interceptor swales. The interceptor swales will have rock check dams to improve sediment removal. The existing railroad tracks are a physical barrier that prevents storm water from leaving the site. Rock construction entrances will be installed at the proposed driveway locations and will help reduce the amount of soil transported to Southwest 7th Street. These measure should be adequate for controlling the drainage during site grading. • i t i i