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Home My WebLink AboutStorm Drainage Computations - PLN General - 5/8/1998 I STORM DRAINAGE COMPUTATIONS SO O FOR L N IL WI MAY 89 1998 FOR WILSON OIL, INC. P.O. BOX 69 LONGVIEW WA 98632 PREPARED BY ADA ENGINEERING, L.L.C. P.O. BOX 847 POULSBO WA 98370 (360) 779-6633 (206) 842-6123 "v A4 10 l •� $8�4 's"CVAL EXPIRES Z '�3 3 SCOPE The project consists of the construction of a"Card-Lock" fueling facility, with two underground storage tanks and three pump islands on approximately 0.22 acres of land. LOCATION The project is located in Belfair WA,just north of the intersection of State Route 3 and State Route 300 which is in Section 29, Township 23 North, Range 1 West, W.M., Mason County, Washington. EXISTING SITE For stormwater computatioins the site will be considered as gravel, as it has been a gravel parking lot for some time. The site slopes from east to west at an average slope of+/-3%. The site is on the west b Highway 300 on the southeast b Highway 3 see Exhibit A . bounded Y g Y � Y g Y � ) DOWN STREAM Stormwater runoff from the site will exit the site on the west side after treatment in an oil/water separator. From the oil/water separator runoff will flow through a 12" CMP, northward to an existing CB. At this CB flows in addition to that of Wilson Oil are conveyed under Hwy 300 to the west through an 18" concrete culvert into an existing drainage ditch approximately 8-10 feet wide and 3-4 feet deep. This ditch flows generally to the west, flowing through a couple of 24" CMPs in the process. This swale intersects a larger stream, which eventually intersects the Union a short distance above where the Union River discharges into Lynch Cove on Hood Canal (see Exhibit B). The downstream appears more than adequate to handle the increased flow from Wilson Oil. WATER QUANTITY DETENTION Due to the adequacy of the downstream, the small amount of runoff from the site, and the lack of space, we propose no water quantity BMP. WATER QUALITY TREATMENT Water quality treatment will be achieved by a CPI oil/water separator designed to treat the 100 year developed storm. BYPASS FLOWS There is a 12" C1VIP that discharges onto the site in the southeast corner that drains parts of Highway 3 and surrounding area. The flow will be bypassed around the site through a ditch as shown on the plans. COMPUTING DESIGN RUNOFF RATES Stormwater runoff rates were determined using WaterWorks 4.11 with the SBUH hydro graph method and type I rain fall for the 24 hour storms. For design conditions the amount of impervious surface was determined using Eaglepoint software. The impervious area was determined to be 0.22 acres (see Exhibit Q. Soil type was assumed to be a Hydrologic group"C" soil.. The pre-developed basin was considered as second gravel, and for type C soil has a curve number of 89 (see Exhibit D). The developed site will be all impervious with a curve number of 98 (see Exhibit D). T,for pre- developed and developed conditions was assumed to be 10 minutes. Rainfall totals were determined from the,isopluvial maps for Washington State by the N.O.A.A. (see Exhibit E). For design storm output see exhibit F. EXffiBIT A i I..L LLL. Q 991 m �0 qp 0 o SUBJECT 0 �00 PROPERTY Ln 9f� SEC.29 T23N, R1W, W.M. vocomo7v HAP N.T.S. EXHIBIT B I Li ,ro \ \ ••'.• .` y \ W. � Wf 8s� LCI oi- D LID W. am LA ct ua u LU 00., EXHIBIT C 2 L,., EXI�JING OPUMP ISLAND ��"COI °J n i SD-SD SD-SD-SD-SO (TYP.) EXISTING CB TOP EL=42.02 X a EXISTING 7 IE IN=38.8 OIL WATER ■ O■ L-5 IE OUT=38.7 2I SEPARATOR o EXISTING EDGE PAVEMENT n o Oet12 4J20 242 an 2a7 238 OE1r47.eo In GF1-4130 OFl-44.70 QE a..90 OM-45.60 �- - 04 247 213 __ - 4 23Q 243 245 - W t2' - -u7o - GE eo o ■ �■ - - O bi .r 214 ® 2 4■ ■ .42. OEL-4130 GElf41 0 044 70 OEJ 45.90 146.8 -- DEL-49.70 m O = Ix � o � O LOA 706 I n 215 220 225 2e1 41 GEL-4140 GEL-4160 OM-44.30 OM-4540 46 0 •)d-49.10 IE=49.9 216 221 226 246 2074140 �- GEL144.50 OEL-44.80 GE1-45.20 GEL-46. 12 CU .] 12 CUP EXISTING UTILITY BUILDING > ��sTti J6 Lr � u AY 208 OEL- 206 GEL-4J 1,, EXHIBIT D STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN Table III-1.3 SCS Western Washington Runoff Curve Numbers (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type lA rainfall distribution, 24-hour storm duration. LAND USE DESCRIPTION CURVE NUMBERS BY HYDROLOGIC SOIL GROUP A B C D Cultivated land(1) : winter condition 86 91 94 95 Mountain open areas: low growing brush & grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94. Open spaces, lawns, parks, golf courses, cemeteries, landscaping. Good condition: grass cover on t75% of the 68 80 86 90 area Fair condition: grass cover on 50-75% of 77 85 90 92 the area Gravel roads & parking lots: 76 85 89 91 Dirt roads & 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) Separate curve number 1.0 DU/GA 15 shall be selected for 1.5 DU/GA 20 pervious & impervious 2.0 DU/GA 25 portions of the site 2.5 DU/GA 30 or basin 3.0 DU/GA 34 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 PUD's, condos, apartments, %impervious commercial businesses & must be industrial areas computed (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Sec. 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. III-1-12 FEBRUARY, 1992 EXHIBIT E STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN 49 124 123 122 121 25 a w • w w auaaa a ism m EL • 1 s � � � h BE r Q OLGA ' C is \ I FRIDAY HARBOR J PORT O v T STA LEY ew MT V , a I NE / 75 40 __ _r� T � \ f w ` 3 30 15 3 2520 I �g / 10 w, 48, �' L �/E ERETT ? 45\ - ,/ m 501 a 337' c 4� �s s 15 c 30 5 a !S 20 1 I 451 �. /rs AT x w 35.. C � T 35\ 40 55 sJ — 5 40 35 COMA � �.. •- u 2 ; 47 AB ROE N l7! B 3035 ae 15 'S JJ - 4�7 CENT20 c 1a• 't5- 55, w a 10 YAKI O 50 r➢.lrL30 , 20 p t 45'' ! 40 35- \ f� ADA 46 3 2 L. ,s. v 55 u , 45s -- _ WASHINGTON a 3 25 B K 10 0 10 20 30 40 : ' P.Pt 05 EN E ---• MILES 20( � I' a ' ` Figure 25 I V . C.,� , _ A�10 % � 25 NOAA ATLAS 2, Volume IX ISOPLLNIALS F 2-YR 24-HR PRECIPITATI N IN Prepared by U.S.Department of cc mmerce TENTHS OF A INCH National Ocesnic and Atmospheric A Iministration National Weather Service,Office of Hydrology Prepared for U.S.Department of Ai riculture, Soil Conservation Service,Engineer ng Division 124 123 122 121 III-1-44 FEBRUARY, 1992 OLGA FRIDAY HARBOR r� � 17.5 71 ou fit I 45 40 l-• y , y STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN 124 123 122 121 49 45 4 _ 80 45.E EL i 40. 2 \ 2 s 1` \ .45 7°�� Usk 40 70 4� TRIO, 'r HARBQR YI -PORT �:IANLk 'S Qt0t 70 5 5 6085 \\ 35 30 / —~ i. .'` 70? se"� .0• t CI_ r -- r4_11-1 10 {TT 5 �- 5 10 6 �, 0 55 4 8I 15' t� to �., 35 QAMto• 1 n 75 80 65. t 5 ` 10 90\ ao7 I OT, j 100 2 1 _ 40�/ n "T 5 � 1 r � iC 0`. 1 Be % �I k" FV 55' �Il �.75 3 g� 47• 7— _ is u '� ` 5 i -ABE E N j r54 _ 165 6 S0 2 _5 u s 70 I i 4'E. TR L 70 �� u - 75 \I 2 6Q iS 22 YAK sd n( 100 45 eo 55 551 80` C- 65�60 55 0 w �0 1 8 ` ADS\��t 4 6 s 6 WASHINGTON 40 ' 1 f e J° 4, tCKLI `6PT TEN E 10 0 10 20 30 40 gp MILES i 40( t s sn 55504535 Figure 30 ! 45 NOAA ATLAS 2, Volume IX 5055 60 65 Prepared by U.S.Department of Cmerce ISOPLUVIALS F 100-YR 24-HR PRECIPIT4'TION ;National Oceanic and Atmospheric Akiminietration I IN TENTHS OF N INCH National Weather Service,Office oflHydrology Prepared for U.S.Department of ABlriculture, Soil Conservation Service,Engineer4 g Division 124 123 122 12 III-1-46 FEBRUARY, 1992 J a EXHIBIT F i 5/4/98 2 :50:55 pm A.D.A. Engineering page 1 KDK WILSON OIL ' BASIN SUMMARY BASIN ID: PRE1 NAME: 6 MONTH EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 1. 89 inches AREA. . : 0.22 Acres 0. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 89. 00 0. 00 TC. . . . : 10. 00 min 0. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 04 cfs VOL: 0. 02 Ac-ft TIME: 480 min BASIN ID: PRE2 NAME: 2 YR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 .50 inches AREA. . : 0. 22 Acres 0. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 89 . 00 0. 00 TC. . . . : 10. 00 min 0. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 11 cfs VOL: 0. 04 Ac-ft TIME: 480 min BASIN ID: PRE3 NAME: 10 YR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 5. 00 inches AREA. . : 0. 22 Acres 0. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 89 . 00 0. 00 TC. . . . : 10. 00 min 0. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 19 cfs VOL: 0. 07 Ac-ft TIME: 480 min BASIN ID: PRE4 NAME: 100 YR EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 6.75 inches AREA. . : 0. 22 Acres 0. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 89 . 00 0. 00 TC. . . . : 10. 00 min 0. 00 min ABSTRACTION CO • 0.20 PEAK RATE: cfs VOL: 0. 10 Ac-ft TIME: 480 min I oo yr- ExtS-n,aco S-raew•l 5/4/98 2 :50:55 pm A.D.A. Engineering page 2 WILSON OIL KDK BASIN SUMMARY BASIN ID: PST1 NAME: 6 MONTH DEVELOPED EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 1.89 inches AREA. . : 0. 00 Acres 0. 22 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 0. 00 98 . 00 TC. . . . . 0. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 130. 00 ns: 0. 0110 p2yr: 1. 89 s: 0. 0538 PEAK RATE: 0. 08 cfs VOL: 0. 03 Ac-ft TIME: 480 min BASIN ID: PST2 NAME: 2 YR DEVELOPED EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 .50 inches AREA. . : 0. 00 Acres 0.22 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 0. 00 98 . 00 TC. . . . . 0. 00 min . 10. 00 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 130. 00 ns: 0. 0110 p2yr: 1. 89 s: 0. 0538 PEAK RATE: 0. 15 cfs VOL: 0. 06 Ac-ft TIME: 480 min BASIN ID: PST3 NAME: 10 YR DEVELOPED EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 5. 00 inches AREA. . : 0. 00 Acres 0. 22 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 0. 00 98 . 00 TC. . . . . 0. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 130. 00 ns: 0. 0110 p2yr: 1. 89 s: 0. 0538 PEAK RATE: 0. 22 cfs VOL: 0. 09 Ac-ft TIME: 480 min BASIN ID: PST4 NAME: 100 YR DEVELOPED EXISTING SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.22 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 6.75 inches AREA. . : 0. 00 Acres 0. 22 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 0. 00 98 . 00 TC. . . . . 0. 00 min 10. 00 min ABSTRACTION COEFF: 0.20 TcReach - Sheet L: 130. 00 ns: 0. 0110 p2yr: 1. 89 s: 0. 0538 PEAK RATE: 0. 30 cfs VOL: 0. 12 Ac-ft TIME: 480 min JbO 5/4/98 2 :50:55 pm A.D.A. Engineering page 3 WILSON OIL KDK HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cf s min. cf\AcFt Acres --------------------------------------------- 1 0. 041 480 749 cf 0. 22 2 0. 114 480 1882 cf 0.22 3 0. 185 480 3012 cf 0.22 4 0. 269 480 4364 cf 0.22 5 0. 081 480 1330 cf 0.22 6 0. 155 480 2609 cf 0. 22 7 0. 223 480 3804 cf 0. 22 8 0. 303 480 5200 cf 0. 22 11 0. 057 550 2609 cf 0. 22 12 0. 185 500 3804 cf 0. 22 13 0.268 490 5200 cf 0. 22