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Home My WebLink AboutWPO200400081 Calculations 1998-01-12 7 . ,. ... „. . ,I 1 i • FONTANA ALBEMARLE COUNTY, VIRGINIA NICHOLS ACCOUNTANCY CORPORATION, INC. STORMWATER MANAGEMENT REPORT ti IW.i McKEE/CARSON CONSULTING ENGINEERS•LANDSCAPE ARCHITECTS•PLANNERS QUEEN CCALOTLA& 301 EAST 2H STREET R ES 22901 (804)979 7522 12 JANUARY, 1998 STORMWATER MANAGEMENT NARRATIVE FONTANA SUBDIVISION 12 JANUARY, 1998 PROJECT DESCRIPTION The site is bounded on the northwest by the Route 20 and on the southwest by Route 250. To the east of the property is the Westminster-Canterbury adult home. The site is currently heavily wooded. There is a major utility easement running northwest to southeast through the center of the property. There also are other more minor utility easements on the property. A detention pond exists near the center of the land. This project will provide new residential housing and roads. Drainage of the site will be through ditches and culverts. HYDROLOGIC METHODOLOGY& ASSUMPTIONS The site consists of two Points of Analysis: Point 1 and Point 2. Point 1 is located near Route 20 at the small private driveway which borders the property on the north side. Point 1 only has one contributing area, Area 1, a 39 acre watershed. Point 2 has multiple subarea contribution. In the existing condition,contributions from Area 2 and 2B are combined at this point. It is necessary to break out a separate Area 2B so that the runoff can be routed through the existing pond and eventually combined with the runoff from Area 2 at Point 2. In the proposed condition, another subarea is created, Area 2A. This is done because Pond 2A is proposed at the outfall of the subarea. Hence the proposed results for Point 2 will show the runoff contribution from Point 2 plus the discharge from Ponds 2A and 2B. The Rational Method is used for hydrologic analysis. Runoff coefficient values are from DCR. Times of concentration are computed by TR-55 methodology. Eagle Point Software's Watershed Modeling is used for all hydrograph and routing computations. BASIN DESIGN The proposed detention basins are designed to detain the proposed 10-year peak so that the discharge at each point is less than or equal to the existing. The 100-year design storm will be safely conveyed through the spillways as the 100-year ultimate water surface elevations are well below the top of the settled embankment. Both Ponds 1 and 2A are over designed to a degree for stormwater management purposes alone. Each facility will also be used as a sediment basin and the guidelines for wet and dry storage require more storage and higher release structures. The intent of the design was to use one basic riser structure which can be easily converted from a sediment basin riser to a stormwater riser,without any major disturbance to the facility. The basin is also designed to treat the first 1/2" of runoff from the site for quantity control.This " or"first flush" is based on the impervious are from the watershed. In both cases the water quality volume provided is much greater than the design requirement.The water quality volume is the storage in the pond from the elevation of the 3" orifice to the elevation of the next orifice. The goal of extended detention is to provide an extended detention period for this volume of 30 hours.However, the orifice size required to do this would have to be very small and thus a 3" orifice(minimum recommended) is used for practical purposes.The 3" orifice is protected by a 6"PVC perforated pipe,wrapped in filter fabric and surrounded by stone. The riser in Pond 1 will incorporate the 12" dry storage orifice as well as the opening in the top of the structure. For Pond 2A,the dry storage orifice-a 10" opening-will be plugged with concrete for permanent stormwater purposes,but will maintain the top opening. Both structures have a rebar trash rack.The 100 year event in Pond 1 will not rise above the top opening and the same event in Pond 2 will barely overtop the opening and will be in weir control. Hence,no anitvortex devices are proposed. RESULTS The results are summarized in the following pages. In both cases,Q's are less than or equal to those of the existing condition. 3 . 044 HYDROLOGIC SUMMARY FONTANA 24-Oct-97 i BY:CLD HYDROLOGIC INPUTS HYDROLOGIC AREA Cw Tc POINT CONDITION ac min 1 EXISTING 37.61 0.20 15.39 2B EXISTING 108.09 0.25 38.09 2 EXISTING 90.38 0.20 39.03 1 PROPOSED 39.03 0.47 15.39 2A PROPOSED 32.38 0.60 20.25 2B PROPOSED 109.73 0.38 38.09 2 PROPOSED 57.97 0.20 39.03 4 WEIGHTED RATIONAL COEFFICIENT PROJECT FONTANA 9633 BY CD DATE 10/24/97 LOCATION AREA 1 REV DATE CONDITION EXISTING - - - PRODUCT LAND USE DESCRIPTION C AREA CxA UNIMPROVED AREA (WOODS) 0.20 37.61 7.52 0.00 0.00 0.00 0.00 0.00 • 37.61 7.52 - - -- - USE Cur 0.20 5 PrI TIME OF CONCENTRATION AND TRVEL TIME PROJECT FONTANA-9633A BY CLD DATE 24-Oct-97 LOCATION 'SUBAREA 1 'REV DATE CONDITION EXISTING SHEET FLOW SURFACE DESCRIPTION WOODED MANNING'S n 0.24I FLOW LENGTH 300.001 ft 2 YEAR 24 HOUR RAINFALL j 4.00 in LAND SLOPE ! j 0.23 ft/ft TRAVEL TIME 0.191 hr SHALLOW CONCENTRATED FLOW SURFACE DESCRIPTION 1 UNPAVED FLOW LENGTH 1100.00 ft WATERCOURSE SLOPE 0.09 ft/ft AVERAGE VELOCITY 4.80 ft/s TRAVEL TIME 0.06 hr CHANNEL FLOW CROSS SECTIONAL AREA 20.001 ft^2 WETTED PERIMETER 20.401ft HYDRAULIC RADIUS 0.98 ft CHANNEL SLOPE — 0.02,ft/ft MANNING'S n 0.23 VELOCITY 0.93 ft/s FLOW LENGTH 0.00 1 ft TRAVEL TIME 0.00 I hr _ TIME OF CONCENTRATION 0.261hr 6 WEIGHTED RATIONAL COEFFICIENT PROJECT FONTANA 9633 BY CD DATE '10/24/97 LOCATION SUBAREA 2 REV -- - DATE CONDITION EXISTING ---_ _-- _-- PRODUCT LAND USE DESCRIPTION C AREA CxA UNIMPROVED AREA (WOODS) 0.20 90.38 18.08 0.00 0.00 0.00 0.00 0.00 90.38 18.08 - - - -- - - -- - ---- -- - -- USE Cw 0.20 - - - r • TIME OF CONCENTRATION AND TRVEL TIME PROJECT FONTANA-9633 BY CLD 'DATE 24-Oct-97 LOCATION SUBARREA 2 ,REV DATE CONDITIOI!EXISTING SHEET FLOW SURFACE DESCRIPTION WOODED r MANNING'S n 0.24 FLOW LENGTH I 300.00 ft 2 YEAR 24 HOUR RAINFALL 4.00 in LAND SLOPE 0.08 ft/ft TRAVEL TIME 0.29,hr SHALLOW CONCENTRATED FLOW SURFACE DESCRIPTION I UNPAVED FLOW LENGTH I 900.001 ft WATERCOURSE SLOPE I 0.11 ft/ft AVERAGE VELOCITY 5.50 ft/s TRAVEL TIME j 0.05 hr CHANNEL FLOW CROSS SECTIONAL AREA 20.00rft^2 WETTED PERIMETER 20.40 ft HYDRAULIC RADIUS 0.98 I ft CHANNEL SLOPE 0.05!ft/ft MANNING'S n 0.23! VELOCITY _ _ 1.43 ft/s FLOW LENGTH 1600.00 ft TRAVEL TIME 0.31 hr TIME OF CONCENTRATION 0.65 hr 8 ‘414 WEIGHTED RATIONAL COEFFICIENT PROJECT FONTANA 9633 BY CD DATE 10/24/97 LOCATION SUBAREA 2B REV DATE CONDITION EXISTING -- PRODUCT_ LAND USE DESCRIPTION C AREA CxA UNIMPROVED AREA (WOODS) 0.20 82.49 16.50 RESIDENTIAL:SINGLE FAMILY 0.40 24.03 9.61 RESIDENTIAL:SINGLE FAMILY 0.40 1.57 0.63 0.00 0.00 0.00 108.09 26.74 USE Cw 1 0.25 9 TIME OF CONCENTRATION AND TRVEL TIME PROJECT FONTANA-9633 BY CLD DATE 24-Oct-97 LOCATION 1 SUBARREA 2B REV DATE CONDITION EXISTING SHEET FLOW SURFACE DESCRIPTION WOODED 1 MANNING'S n 0.24 FLOW LENGTH 300.00 ft 2 YEAR 24 HOUR RAINFALL 4.00i in LAND SLOPE 0.13!ft/ft TRAVEL TIME 0.24 hr SHALLOW CONCENTRATED FLOW SURFACE DESCRIPTION UNPAVED FLOW LENGTH — 950.00!ft WATERCOURSE SLOPE 0.231 ft/ft AVERAGE VELOCITY i 7.00I ft/s TRAVEL TIME 0.04 hr CHANNEL FLOW CROSS SECTIONAL AREA 20.001ft^2 WETTED PERIMETER 20.40 ft HYDRAULIC RADIUS 0.98 ft CHANNEL SLOPE 0.06 ft/ft MANNING'S n 0.23 VELOCITY 1.57 ft/s FLOW LENGTH 2000.00 ft TRAVEL TIME 0.35 hr TIME OF CONCENTRATION 0.63 hr 10 WEIGHTED RATIONAL COEFFICIENT PROJECT FONTANA 9633 BY CD DATE 10/24/97 LOCATION SUBAREA 1 REV DATE CONDITION PROPOSED PRODUCT LAND USE DESCRIPTION C AREA CxA UNIMPROVED AREA WOODS) 0.20 2.27 0.45 UNIMPROVED AREA (WOODS) 0.20 9.96 1.99 RESIDENTIAL:SINGLE FAMILY 0.60 26.80 16.08 0.00 --------- - 0.00 0.00 - - 39.03 18.53 USE Cw 0.47 1 -- -- - -- - ---- Cwexl.xis Page 11 i TIME OF CONCENTRATION AND TRVEL TIME i PROJECT FONTANA-9633 BY CLD 'DATE 24-Oct-97 LOCATION .SUBAREA 1 REV DATE CONDITION'PROPOSED j SHEET FLOW t SURFACE DESCRIPTION WOODED MANNING'S n I 0.24 FLOW LENGTH 300.00 ft 2 YEAR 24 HOUR RAINFALL 4.00 in LAND SLOPE 0.23 ft/ft TRAVEL TIME 0.19 hr SHALLOW CONCENTRATED FLOW SURFACE DESCRIPTION UNPAVED FLOW LENGTH ' 1100.00 ft WATERCOURSE SLOPE i 0.091ft/ft AVERAGE VELOCITY 4.80,ft/s TRAVEL TIME ; I 0.06'hr P CHANNEL FLOW CROSS SECTIONAL AREA 20.00 ft^2 WETTED PERIMETER I 20.40 ft HYDRAULIC RADIUS — - 0.98 ft CHANNEL SLOPE - 0.02;ft/ft MANNING'S n 0.231 VELOCITY T _ 0.93'ft/s FLOW LENGTH 0.00 ft TRAVEL TIME 0.01:k hr TIME OF CONCENTRATION 0.261hr Tcexl.xls Page 12 1 WEIGHTED RATIONAL COEFFICIENT PROJECT FONTANA 9633 BY CD DATE 10/24/97 LOCATION SUBAREA 2 REV DATE CONDITION PROPOSED -- -- _ PRODUCT LAND USE DESCRIPTION C AREA CxA UNIMPROVED:WOODS 0.20 57.97 11.59 0.00 0.00 0.00 57.97 11.59 USE Cw I 0.20 -- 1 i - Cwexl.xls Page 13 TIME OF CONCENTRATION AND TRVEL TIME PROJECT 'FONTANA-9633 BY CLD DATE 24-Oct-97 LOCATION I SUBARREA 2 REV DATE CONDITION PROPOSED' SHEET FLOW SURFACE DESCRIPTION WOODED MANNING'S n 0.24 FLOW LENGTH C 300.00 ft 2 YEAR 24 HOUR RAINFALL I 4.00 in LAND SLOPE I 0.08 ft/ft TRAVEL TIME r 0.291 hr SHALLOW CONCENTRATED FLOW SURFACE DESCRIPTION UNPAVED FLOW LENGTH I I 900.00 ft WATERCOURSE SLOPE 1 0.111ft/ft AVERAGE VELOCITY ' 5.501ft/s TRAVEL TIME I 0.05 hr CHANNEL FLOW _ CROSS SECTIONAL AREA 20.00Ift^2 WETTED PERIMETER 20.40ift HYDRAULIC RADIUS I 0.981 ft CHANNEL SLOPE ; 0.051ft/ft MANNING'S n i 1 j 0.23 VELOCITY I 1.431 ft/s FLOW LENGTH 1600.00 ft TRAVEL TIME i 0.311 hr TIME OF CONCENTRATION 0.65ihr Tcexl.xls Page 14 WEIGHTED RATIONAL COEFFICIENT PROJECT FONTANA 9633 BY CD DATE - 10/24/97 ------------------- LOCATION SUBAREA 2A REV DATE CONDITION PROPOSED PRODUCT LAND USE DESCRIPTION C AREA CxA RESIDENTIAL:SINGLE FAMILY 0.60 32.38 19.43 0.00 0.00 0.00 32.38 19.43 - USE Cw 0.60 Cwexl.xls Page 15 TIME OF CONCENTRATION AND TRVEL TIME PROJECT FONTANA-9633 BY CLD DATE 24-Oct-97 LOCATION SUBAREA 2A REV DATE CONDITION,PROPOSED SHEET FLOW SURFACE DESCRIPTION WOODED MANNING'S n ! 0.241 FLOW LENGTH 300.0011 ft 2 YEAR 24 HOUR RAINFALL 4.001 in LAND SLOPE 0.13 1 ft/ft TRAVEL TIME ! 0.24 hr i I SHALLOW CONCENTRATED FLOW SURFACE DESCRIPTION UNPAVED FLOW LENGTH 330.00,ft WATERCOURSE SLOPE 0.11 ft/ft AVERAGE VELOCITY 5.50I ft/s TRAVEL TIME i 0.02 hr CHANNEL FLOW CROSS SECTIONAL AREA 20.00 ft^2 WETTED PERIMETER 20.40 ft HYDRAULIC RADIUS 0.98 ft CHANNEL SLOPE 0.15 j ft/ft MANNING'S n 0.23 VELOCITY 2.48 ft/s FLOW LENGTH _ 700.00 1 ft TRAVEL TIME 0.081 hr TIME OF CONCENTRATION 0.34 hr Tcexl.xls Page 16 WEIGHTED RATIONAL COEFFICIENT PROJECT FONTANA 9633 BY CD DATE 10/24/97_ LOCATION SUBAREA 2B REV DATE CONDITION PROPOSED PRODUCT LAND USE DESCRIPTION C AREA CxA RESIDENTIAL:SINGLE FAMILY 0.60 37.91 22.75 RESIDENTIAL:SINGLE FAMILY 0.40 24.03 9.61 UNIMPROVED:WOODS 0.20 46.22 9.24 RESIDENTIAL:SINGLE FAMILY 0.40 1.57 0.63 0.00 0.00 109.73 42.23 USE Cw 0.38 --------- --- Cwexl.xls Page 17 TIME OF CONCENTRATION AND TRVEL TIME PROJECT FONTANA-9633 BY CLD DATE 24-Oct-97 LOCATION SUBAREA 26 REV DATE CONDITION PROPOSED SHEET FLOW SURFACE DESCRIPTION j WOODED~ MANNING'S n i [ 0.24 FLOW LENGTH 300.001 ft 2 YEAR 24 HOUR RAINFALL 4.001 in LAND SLOPE I 0.13 ft/ft TRAVEL TIME 0.241 hr SHALLOW CONCENTRATED FLOW SURFACE DESCRIPTION UNPAVED FLOW LENGTH 950.001 ft WATERCOURSE SLOPE I I 0.23 I ft/ft AVERAGE VELOCITY I 7.00!ft/s TRAVEL TIME 0.04'hr CHANNEL FLOW CROSS SECTIONAL AREA 20.00!ft^2 WETTED PERIMETER 20.40 ft HYDRAULIC RADIUS 0.98Ift CHANNEL SLOPE _ 0.06 ft/ft MANNING'S n 0.23 VELOCITY 1.57 ft/s FLOW LENGTH I 2000.00 I ft TRAVEL TIME 0.35 hr TIME OF CONCENTRATION 0.63 hr Tcexl.xls Page 18 Sheet1 Riser Flotation Analysis Project Fontana By CD Date 10/24/97 Location Pond 1 Riser Checked Date Description VDOT DI-1 Inlet as Riser Rectangular Riser Length 4.17 ft Width 4.17 ft Wall 1 ft Top Elevation 378 ft Invert Out 370 ft Volume of Riser 101.44 cf Volume of Air 37.67 cf Base Length 4.17 ft Width 4.17 ft Base 0.75 ft Design Parameters Safety Factor 20% Weight of Material 150.00 pcf Outlet Pipe Diameter 24.00 in Trash Rack 100.00 lb Grate 0.00 lb Volume of Water Displaced 139.11 cf Buoyant Force 8680.54 lb Factored Buoyant Force 10416.65 lb Weight of Structure 16801.01 lb Page 19 Sheetl Riser Flotation Analysis Project Fontana By CD Date 10/24/97 Location Pond 2A Riser Checked Date Description VDOT DI-1 Inlet as Riser Rectangular Riser Length 4.17 ft Width 4.17 ft Wall 1 ft Top Elevation 421.5 ft Invert Out 413.8 ft Volume of Riser 97.64 cf Volume of Air 36.26 cf Base Length 4.17 ft Width 4.17 ft Base 0.75 ft Design Parameters Safety Factor 20% Weight of Material 150.00 pcf Outlet Pipe Diameter 24.00 in Trash Rack 100.00 lb Grate 0.00 lb Volume of Water Displaced 133.89 cf Buoyant Force 8355.02 lb Factored Buoyant Force 10026.02 lb Weight of Structure 16230.41 lb Page 20 Sheet1 Extended Detention Design Project Fontana 9633 By CD Date 10/24/97 Location Pond 1 Checked Date Description Design Depth (first flush) 0.50 in Proposed Impervious Area 1.51 ac Existing Impervious Area 0.00 ac Treatable Area 1.51 ac Water Quality Volume 2740.65 cf Corresponding Basin Elevation 374.63 ft Release Period 30.00 hr Release Rate q 0.03 cfs Centerline Elevation Orifice 370.33 ft Average Head 2.15 ft Area Orifice 0.00 sf Diameter Orifice 0.52 in Use Diameter 3.00 in Page 21 Sheet1 Extended Detention Design Project Fontana 9633 By CD Date 10/24/97 Location Pond 2A Checked Date Description _ Design Depth(first flush) 0.50 in Proposed Impervious Area 2.02 ac Existing Impervious Area 0.00 ac Treatable Area 2.02 ac Water Quality Volume 3666.30 cf Corresponding Basin Elevation 416.09 ft Release Period 30.00 hr Release Rate q 0.03 cfs Centerline Elevation Orifice 414.13 ft Average Head 0.98 ft Area Orifice 0.01 sf Diameter Orifice 1.03 in Use Diameter 3.00 in Page 22 Outlet Protection Project Fontana By CD Date 10/24/97 Location Outlet of Pond 1 Checked Date Condition 10 Yr Diameter of Outlet Pipe, Do 24 " Design Discharge, Q 0.59 cfs For TW< 1/2*Diameter of Outlet Pipe: From Plate 3.18-3: d50 0.50 ft Minimum Length of Apron, La 12.00 ft Width 14.00 ft 3Do 6.00 ft Thickness of apron, t 1.50 ft A Ca o i` -4soirit Toby" 0 1 PIPE tr``>< grip �Pooliys_,+s>1%0 o n ;yam+ :Vyl j+ Q ___ stirta DIAV Do �``` foitel `00 La Op.xls Page 23 Outlet Protection Project Fontana By CD Date 10/24/97 Location Outlet of Pond 2A Checked Date Condition 10 Yr Diameter of Outlet Pipe, Do 24 " Design Discharge, Q 4.62 cfs For TW< 1/2*Diameter of Outlet Pipe: From Plate 3.18-3: d50 0.50 ft Minimum Length of Apron, La 12.00 ft Width 14.00 ft 3Do 6.00 ft Thickness of apron, t 1.50 ft la Oka -s MG r o ' PIPE d AL , \`tom Q n mmi7rio,* mot- nriti DIAV Do wow 41 La Op.xls Page 24 CHANNEL SECTION PROJECT FONTANA BY CD D PROJECT NUMBER 9633 I REVIEWED DATE 24-Oct-97 DESCRIPTION POND 1 LOW FLOW CHANNEL B - - ---- Z 4.0 :1 n- - 0 024 S° - 2.00% 60.00 cfs di ---- 0.99 ft - -- -- _ ASECTION 8.87 sf PSECTION 13.16 ft --- - _ ---- RSECTION 0.67 V — - �di) --- -- -- 6.75 fps - --- -- ---- - -- - - - -- - - - V(Q/A) 6.76 fps -- USE d 1.00 ft - - - -- -- - - --— d x Z B d x Z f,,,.awc.„.„ zr.1 A w, la N .. Yn,a-, l''' — .., - ••rvrrrwa-:wvwv:..wwv..av1.a-:..v.avw.vwwwvwa-:wvr.v...wwwv G.) STORMWATER CONVEYANCE CHANNEL CHANNEL SECTION PROJECT FONTANA BY CD PROJECT NUMBER 9633 REVIEWED DATE 24-Oct-97 DESCRIPTION POND 2A LOW FLOW CHANNEL 5.0 ft Z 4.0 :1 n 0.024 2.000/0 Q 54.28 cfs dl 0.94 ft ASECTION 8.23 sf PSECTION 12.75 ft RSECTION 0.65 V(dl) 6.56 fps AQ/A) 6.59 fps USE d 1.00ft d x Z B dxZ _ _ _ _ _ _ STORMWATER CONVEYANCE CHANNEL 111.1111111111111 tt .4, •ftiloi, - sP4 — ".` Ail *A. Att ,r; . TEMPORARY SEDIMENT BASIN I I- PR JECT i j FONTANA PROJ NO. 9633 BA'S"�_ # POND 1 DATE 10/24/97 LOC ` ON 1 BY CLD INPUT DRAIN .a E AREA 39.0 ac Iv .1 tv BASIN V LUME DESIGN v:= v>. WET ST AGE j 1. MINIM$M REQUIRED VOLUME 2615.01 cy . AVAIL4BLE BASIN VOLUME li AVERAGE END AREA - BASIN VOLUME ESTIMATES it ELEVATION AREA VOLUME VOLUME TOTAL sf cf cy cy — — k 370.2 0.00 0.00 2,376.00 88.00 c _ 372 2,640.00 88.00 22,715.00 841.30 4" 374 20,075.00 ! 929.30 4 1,41,, 45,223.00 1,674.93 1 376 25,148.00 2,604.22 76,219.00 2,822.93 1 - — 378 51,071.00 5,427.15 129,534.00 4,797.56 380 78,463.00 10,224.70 ' '.X r e - . .. -EQUIRED WET STORAGE VOLUME i 2,615.01 cy PPROX. ELEVATION _ 376.01 ray 3. EXC / E 0 CUBIC YARDS 4 27 TEMPORARY SEDIMENT BASIN PROJECT FONTANA PROJ NO. 9633 BASIN # POND 1 DATE 10/24/97 LOCATION 1 BY CLD 4. AVAILABLE VOLUME BEFORE CLEANOUT REQUIRED 1307.51 cy 5. ELEVATION CORRESPONDING TO CLEANOUT LEVEL 374.45 6. DISTANCE FROM DEWATERING ORIFICE TO C/O LEVEL 'INVERT DEWATERING ORIFICE R'OD 376.01 INVERT DEWATERING ORIFICE USED 376.01 APPROX. VOLUME AT INVERT USED 2618.34 DISTANCE FROM INVERT TO C/O LEVEL 1.56 ft DISTANCE ACCEPTABLE WET STORAGE VOLUME ACCEPTABLE ' I DRY STORAGE 1 7. MINIMUM REQUIRED VOLUME ; 2615.01 cy 8. TOTAL AVAILABLE VOLUME AT CREST OF RISER CREST OF RISER 378.00 APPROX. AVAILABLE TOTAL VOLUME 5427.15cy ADEQUATE DRY STORAGE VOLUME 9. DIAMETER OF DEWATERING ORIFICE q _ 3.51 cfs d(1ST ITERATION) 11.58 in d(2nd ITERATION) 12.41 in d(3rd ITERATION) j 12.481 in d(4th ITERATION) ! 12.491 in I 1 ! USE d ! j 121 in 10. DIAMETER OF FLEXIBLE TUBING 15;in STANDARD SIZE I I 11. THRU 25. SEE STORMWATER CALCULATIONS 28 TEMPORARY SEDIMENT BASIN PROJECT FONTANA I PROJ NO. 9633 BASIN # POND 2A DATE 10/24/97 LOCATION ' BY I CLD INPUT DRAINAGE AREA 32.38 ac r BASIN VOLUME DESIGN WET STORAGE I i 1. MINIMUM REQUIRED VOLUME I 2169.46 cy 2. AVAILABLE BASIN VOLUME AVERAGE END AREA - BASIN VOLUME ESTIMATES ELEVATION AREA VOLUME VOLUME TOTAL sf cf cy cy 414.2 0.00 0.00 _ 2,475.00 91.67 416 I 2,750.00 91.67 25,845.00 , 957.22 418 23,095.00 j 1,048.89 _ 48,699.00 1,803.67 420 25,604.00 2,852.56 53,821.00 1,993.37 422 28,217.00 + 4,845.93 59,174.00 2,191.63 424 30,957.00 7,037.56 REQUIRED WET STORAGE VOLUME 2,169.46 :cy _ APPROX. ELEVATION I 419.241 3. EXCAVATE 0 CUBIC YARDS ._ Page 29 Worksheet in 10-97, 9633 H&H REPORT.obd 25 TEMPORARY SEDIMENT BASIN PROJECT ! FONTANA PROJ NO. 9633 BASIN # POND 2A DATE 10/24/97 LOCATION _ BY CLD 4. AVAILABLE VOLUME BEFORE CLEANOUT REQUIRED 1084.731cy 5. ELEVATION CORRESPONDING TO CLEANOUT LEVEL 418.041 6. DISTANCE FROM DEWATERING ORIFICE TO C/O LEVEL INVERT DEWATERING ORIFICE R'QD 419.241 INVERT DEWATERING ORIFICE USED _ 419.251 APPROX. VOLUME AT INVERT USED ' 1 2176.181 DISTANCE FROM INVERT TO C/O LEVEL 1.21 ft DISTANCE ACCEPTABLE WET STORAGE VOLUME ACCEPTABLE DRY STORAGE 7. MINIMUM REQUIRED VOLUME i 2169.46 cy 8. TOTAL AVAILABLE VOLUME AT CREST OF RISER CREST OF RISER I _ 421.501 APPROX. AVAILABLE TOTAL VOLUME 4347.581cy ADEQUATE DRY STORAGE VOLUME 9. DIAMETER OF DEWATERING ORIFICE 2.71'cfs d(1ST ITERATION) _ 9.87 in d(2nd ITERATION) 10.381in d(3rd ITERATION) 10.41!in d(4th ITERATION) ! 10.41!in USE d 101 in 10. DIAMETER OF FLEXIBLE TUBING 121 in STANDARD SIZE 11.THRU 25. SEE STORMWATER CALCULATIONS Page 30 Worksheet in 10-97, 9633 H&H REPORT.obd 25 • SE CURVE- WESTMINSTER POND EL AREA 429 1055 430 8771 431 15081 432 21166 433 25652 434 31486 435 37635 436 42874 437 48160 438 53053 439 60010 440 67244 441 75149 442 83804 31 EAGLE POINT HYDROLOGIC AND ROUTING COMPUTATIONS /PALI McKEE/CARSON CONSULTING ENGINEERS• LANDSCAPE ARCHITECTS• PLANNERS QUEEN CHARLO 1 I h SQUARE 301 EAST HIGH STREET CHARLO I IhSVILLE,VIRGINIA 22901 (804)979 7522 21 OCTOBER, 1997 Page 32 10-97, 9633 H&H REPORT.obd • Key to Eagle Point H&H Calculations The following example is to provide an explanation of the coding used for the Eagle Point H&H computations following this page: SWM POND FOR POINT OR WATERSHED I HYDROGRAPH POINT NUMBER NUMBER DEVELOPMENT STATE. EX=EXISTING PR=PROPOSED / (PR2B010 + POND2B) + PR2_010 + R2A010 INDICATES "COMBINED WITH" ISTORM FREQUENCY I INDICATES "ROUTED THROUGH" 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 1 TYPE : MOD. RATIONAL DESCRIPTION : EX1_010 [HYDROGRAPH INFORMATION] Peak Discharge = 34.18 (cfs) Volume = 0.73 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.20000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 37.61 0 0 .20000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 15.39 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.17 (in) Return Period = 10 (yr) Storm Duration = 0.26 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 2 TYPE : MOD. RATIONAL DESCRIPTION : EX2B010 [HYDROGRAPH INFORMATION] Peak Discharge = 74.20 (cfs) Volume = 3 .90 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.25000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] 33 [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 108.09 0 0.25000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 38.09 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.74 (in) Return Period = 10 (yr) Storm Duration = 0.63 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 3 TYPE : MOD. RATIONAL DESCRIPTION : EX2_010 [HYDROGRAPH INFORMATION] Peak Discharge = 48.88 (cfs) Volume = 2.63 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.20000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 90.37 0 0.20000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 39.03 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.76 (in) Return Period = 10 (yr) Storm Duration = 0.65 (hr) 34 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 4 TYPE : MOD. RATIONAL DESCRIPTION : PR1_010 [HYDROGRAPH INFORMATION] Peak Discharge = 83 .36 (cfs) Volume = 1.77 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.47000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 39.03 0 0.47000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 15.39 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.17 (in) Return Period = 10 (yr) Storm Duration = 0.26 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 5 TYPE : MOD. RATIONAL DESCRIPTION : PR2A010 [HYDROGRAPH INFORMATION] Peak Discharge = 76.50 (cfs) Volume = 2.15 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.60000 Receding limb factor = 1.00000 35 [BASIN DESCRIPTION] Watershed Area = 32.38 (ac) Runoff coefficient = 0.60 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 20.40 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.34 (in) Return Period = 10 (yr) Storm Duration = 0.34 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 6 TYPE : MOD. RATIONAL DESCRIPTION : PR2B010 [HYDROGRAPH INFORMATION] Peak Discharge = 112.68 (cfs) Volume = 5.86 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.38000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 107.48 0 0.38000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 37 .80 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.74 (in) Return Period = 10 (yr) Storm Duration = 0.63 (hr) 36 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 7 TYPE : MOD. RATIONAL DESCRIPTION : PR2_010 [HYDROGRAPH INFORMATION] Peak Discharge = 31.36 (cfs) Volume = 1.69 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.20000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 57 .97 0 0.20000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 39.03 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.76 (in) Return Period = 10 (yr) Storm Duration = 0.65 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 8 TYPE : RESER STOR. IND DESCRIPTION : EX2B010+POND2B [HYDROGRAPH INFORMATION] Peak Discharge = 54.58 (cfs) Volume = 3 .90 (acft) Peak Elevation = 431.97 (ft) [RESERVOIR STRUCTURE INFORMATION] Reservoir # = 1 Description = EXISTING POND2B (W/C POND) Storage type = MAN STAGE/AREA 37 Max storage = 529238.00 Cuft Discharge type = COMP STAGE/DISC Max discharge = 134.31 cfs [RESERVOIR INFORMATION] Reservoir # = 1 Reservoir Description = EXISTING POND2B (W/C POND) [INFLOW HYDROGRAPH INFORMATION] Hydrograph # = 2 Hydrograph Description = EX2B010 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 9 TYPE : COMBINE DESCRIPTION : (EX2B010+POND2B) +EX2_010 [HYDROGRAPH INFORMATION] Peak Discharge = 97.01 (cfs) Volume = 6.53 (acft) [COMBINE HYDROGRAPH RECORD #] HYDROGRAPH # 8 TYPE : RESER STOR IND DESCRIPTION EX2B010+POND2B Peak Discharge = 54.58 (cfs) Time to Peak = 0.80 (hr) Time Interval = 0.02 (hr) HYDROGRAPH # 3 TYPE : MOD. RATIONAL DESCRIPTION EX2_010 Peak Discharge = 48.88 (cfs) Time to Peak = 0.65 (hr) Time Interval = 0.02 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 10 TYPE : RESER STOR. IND DESCRIPTION : PR2B010+POND2B [HYDROGRAPH INFORMATION] Peak Discharge = 71.00 (cfs) Volume = 5.86 (acft) Peak Elevation = 433 .26 (ft) 38 [RESERVOIR STRUCTURE INFORMATION] Reservoir # = 1 Description = EXISTING POND2B (W/C POND) Storage type = MAN STAGE/AREA Max storage = 529238.00 Cuft Discharge type = COMP STAGE/DISC Max discharge = 134.31 cfs [RESERVOIR INFORMATION] Reservoir # = 1 Reservoir Description = EXISTING POND2B (W/C POND) [INFLOW HYDROGRAPH INFORMATION] Hydrograph # = 6 Hydrograph Description = PR2B010 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 11 TYPE : COMBINE DESCRIPTION : (PR2_+PR2A+(PR2B+POND2B) )010 [HYDROGRAPH INFORMATION] Peak Discharge = 123 .03 (cfs) Volume = 9.70 (acft) [COMBINE HYDROGRAPH RECORD #] HYDROGRAPH # 7 TYPE : MOD. RATIONAL DESCRIPTION PR2_010 Peak Discharge = 31.36 (cfs) Time to Peak = 0.65 (hr) Time Interval = 0.02 (hr) HYDROGRAPH # 5 TYPE : MOD. RATIONAL DESCRIPTION PR2A010 Peak Discharge = 76.50 (cfs) Time to Peak = 0.34 (hr) Time Interval = 0.02 (hr) HYDROGRAPH # 10 TYPE : RESER STOR. IND DESCRIPTION PR2B010+POND2B Peak Discharge = 71.00 (cfs) Time to Peak = 0.90 (hr) Time Interval = 0.10 (hr) 39 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 12 TYPE : RESER STOR. IND DESCRIPTION : PR2A010+POND2A [HYDROGRAPH INFORMATION] Peak Discharge = 0.60 (cfs) Volume = 1.09 (acft) Peak Elevation = 420.29 (ft) [RESERVOIR STRUCTURE INFORMATION] Reservoir # = 2 Description = PROPOSED POND 2A Storage type = MAN STAGE/AREA Max storage = 191383 .81 Cuft Discharge type = COMP STAGE/DISC Max discharge = 47.12 cfs [RESERVOIR INFORMATION] Reservoir # = 2 Reservoir Description = PROPOSED POND 2A [INFLOW HYDROGRAPH INFORMATION] Hydrograph # = 5 Hydrograph Description = PR2A010 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 14 TYPE : MOD. RATIONAL DESCRIPTION : PR2A100 [HYDROGRAPH INFORMATION] Peak Discharge = 113 .36 (cfs) Volume = 3 .19 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0 . 60000 Receding limb factor = 1 .00000 [BASIN DESCRIPTION] [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 40 32 .38 0 0 .60000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 20 .40 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.98 (in) Return Period = 100 (yr) Storm Duration = 0.34 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 15 TYPE : RESER STOR. IND DESCRIPTION : PR2A100+POND2A [HYDROGRAPH INFORMATION] Peak Discharge = 13 .39 (cfs) Volume = 1.67 (acft) Peak Elevation = 421.75 (ft) [RESERVOIR STRUCTURE INFORMATION] Reservoir # = 2 Description = PROPOSED POND 2A Storage type = MAN STAGE/AREA Max storage = 191383 .81 Cuft Discharge type = COMP STAGE/DISC Max discharge = 47.12 cfs [RESERVOIR INFORMATION] Reservoir # = 2 Reservoir Description = PROPOSED POND 2A [INFLOW HYDROGRAPH INFORMATION] Hydrograph # = 14 Hydrograph Description = PR2A100 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 17 41 TYPE : MOD. RATIONAL DESCRIPTION : PR2A025 [HYDROGRAPH INFORMATION] Peak Discharge = 96.07 (cfs) Volume = 2.46 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.60000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] Watershed Area = 32 .38 (ac) Runoff coefficient = 0 . 60 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 18 .61 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.53 (in) Return Period = 25 (yr) Storm Duration = 0.31 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 19 TYPE : RESER STOR. IND DESCRIPTION : PR1_010+POND1_ [HYDROGRAPH INFORMATION] Peak Discharge = 0.95 (cfs) Volume = 1.07 (acft) Peak Elevation = 376.00 (ft) [RESERVOIR STRUCTURE INFORMATION] Reservoir # = 5 Description = PROPOSED POND 1_ Storage type = MAN STAGE/AREA Max storage = 276111.00 Cuft Discharge type = COMP STAGE/DISC Max discharge = 46.37 cfs [RESERVOIR INFORMATION] Reservoir # = 5 Reservoir Description = PROPOSED POND 1_ 42 [INFLOW HYDROGRAPH INFORMATION] Hydrograph # = 4 Hydrograph Description = PR1_010 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 20 TYPE : MOD. RATIONAL DESCRIPTION : PR1_100 [HYDROGRAPH INFORMATION] Peak Discharge = 122 .63 (cfs) Volume = 2.60 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.47000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] Watershed Area = 39.03 (ac) Runoff coefficient = 0.47 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 15.39 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.71 (in) Return Period = 100 (yr) Storm Duration = 0.26 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 21 TYPE : RESER STOR. IND DESCRIPTION : PR1_100+POND1_ [HYDROGRAPH INFORMATION] Peak Discharge = 3 .74 (cfs) Volume = 2 .55 (acft) Peak Elevation = 377.00 (ft) 43 [RESERVOIR STRUCTURE INFORMATION] Reservoir # = 5 Description = PROPOSED POND 1_ Storage type = MAN STAGE/AREA Max storage = 276111.00 Cuft Discharge type = COMP STAGE/DISC Max discharge = 46.37 cfs [RESERVOIR INFORMATION] Reservoir # = 5 Reservoir Description = PROPOSED POND 1_ [INFLOW HYDROGRAPH INFORMATION] Hydrograph # = 20 Hydrograph Description = PR1_100 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 22 TYPE : MOD. RATIONAL DESCRIPTION : PR1_025 [HYDROGRAPH INFORMATION] Peak Discharge = 122 .63 (cfs) Volume = 2 .60 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0 .47000 Receding limb factor = 1 .00000 [BASIN DESCRIPTION] Watershed Area = 39.03 (ac) Runoff coefficient = 0.47 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 15.39 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 1.71 (in) Return Period = 100 (yr) Storm Duration = 0.26 (hr) 44 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 26 TYPE : COMBINE DESCRIPTION : (PR2_+(PR2A+POND2A)+(PR2B+POND2B) ) 010 [HYDROGRAPH INFORMATION] Peak Discharge = 97.21 (cfs) Volume = 8.64 (acft) [COMBINE HYDROGRAPH RECORD #] HYDROGRAPH # 7 TYPE : MOD. RATIONAL DESCRIPTION : PR2_O10 Peak Discharge = 31.36 (cfs) Time to Peak = 0.65 (hr) Time Interval = 0.02 (hr) HYDROGRAPH # 12 TYPE : RESER STOR. IND DESCRIPTION : PR2AO10+POND2A Peak Discharge = 0.60 (cfs) Time to Peak = 0.68 (hr) Time Interval = 0.02 (hr) HYDROGRAPH # 10 TYPE : RESER STOR. IND DESCRIPTION : PR2B010+POND2B Peak Discharge = 71.00 (cfs) Time to Peak = 0.90 (hr) Time Interval = 0.10 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 27 TYPE : MOD. RATIONAL DESCRIPTION : PR1_002 [HYDROGRAPH INFORMATION] Peak Discharge = 60.21 (cfs) Volume = 1.28 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.47000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] Watershed Area = 39 . 03 (ac) Runoff coefficient = 0.47 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 15 . 39 (min) 45 [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 0.84 (in) Return Period = 2 (yr) Storm Duration = 0.26 (hr) 10/22/97 Page 1 HYDROGRAPH REPORT RECORD NUMBER : 28 TYPE : MOD. RATIONAL DESCRIPTION : PR2A002 [HYDROGRAPH INFORMATION] Peak Discharge = 54.28 (cfs) Volume = 1.53 (acft) Multiplication factor = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Runoff Coefficient = 0.60000 Receding limb factor = 1.00000 [BASIN DESCRIPTION] [WEIGHTED WATERSHED AREA] DESCRIPTION AREA CN# RUNOFF COEF 32.38 0 0. 60000 [TIME CONCENTRATION -- USER DEFINED] Time of Concentration = 20.40 (min) [RAINFALL DESCRIPTION] Distribution Type = SYNTHETIC Total Precipitation = 0.95 (in) Return Period = 2 (yr) Storm Duration = 0.34 (hr) 10/22/97 Page 1 RESERVOIR REPORT RECORD NUMBER : 5 STORAGE TYPE : MAN STAGE/AREA DISCHARGE TYPE : COMP STAGE/DISC DESCRIPTION : PROPOSED POND 1_ 46 [RATING CURVE LIMIT] Minimum Elevation = 370.00 (ft) Maximum Elevation = 380.00 (ft) Elevation Increment = 0.50 (ft) [STAGE STORAGE INFORMATION] Input file = NULL Output file = NULL [Manual Contour Area vs. Elevation] ELEVATION CONTOUR AREA (ft) (sqft) 372 .00 2640.00 374.00 20075.00 376.00 25148.00 378.00 51071.00 380.00 78463 .00 [STAGE DISCHARGE INFORMATION] OUTLET STRUCTURE: STR # 4 TYPE : STAND PIPE WEIR DESCRIPTION : POND 1_ RELEASE STRUCTURE 10/22/97 Page 1 RESERVOIR REPORT RECORD NUMBER : 2 STORAGE TYPE : MAN STAGE/AREA DISCHARGE TYPE : COMP STAGE/DISC DESCRIPTION : PROPOSED POND 2A [RATING CURVE LIMIT] Minimum Elevation = 413 .75 (ft) Maximum Elevation = 424.00 (ft) Elevation Increment = 0.50 (ft) [STAGE STORAGE INFORMATION] Input file = NULL Output file = NULL [Manual Contour Area vs. Elevation] ELEVATION CONTOUR AREA (ft) (sqft) 416.00 3276.00 47 418.00 23095.00 420.00 25604.00 422.00 28217.00 424.00 30957 .00 [STAGE DISCHARGE INFORMATION] OUTLET STRUCTURE: STR # 2 TYPE : STAND PIPE WEIR DESCRIPTION : PROPOSED POND 2A RELEASE STRUCTURE 10/22/97 Page 1 RESERVOIR REPORT RECORD NUMBER : 1 STORAGE TYPE : MAN STAGE/AREA DISCHARGE TYPE : COMP STAGE/DISC DESCRIPTION : EXISTING POND2B (W/C POND) [RATING CURVE LIMIT] Minimum Elevation = 428.50 (ft) Maximum Elevation = 442.00 (ft) Elevation Increment = 0.50 (ft) [STAGE STORAGE INFORMATION] Input file = NULL Output file = NULL [Manual Contour Area vs. Elevation] ELEVATION CONTOUR AREA (ft) (sqft) 429.00 1055.00 430.00 8771.00 431.00 15081.00 432 .00 21166.00 433 .00 25652 .00 434.00 31486.00 435.00 37635.00 436.00 42874.00 437.00 48160.00 438.00 53053 .00 439.00 60010.00 440.00 67244.00 441.00 75149.00 442.00 83804.00 [STAGE DISCHARGE INFORMATION] OUTLET STRUCTURE: STR # 1 TYPE : CIRCULAR CONCRETE w/ groove end projecting DESCRIPTION : EXISTING WESTMINSTER RELEASE STRUCTURE 48 f 10/22/97 Page 1 OUTLET STRUCTURE REPORT RECORD NUMBER : 4 TYPE : STAND PIPE WEIR DESCRIPTION : POND 1_ RELEASE STRUCTURE [RATING CURVE LIMIT] Minimum Elevation = 370.00 (ft) Maximum Elevation = 380.00 (ft) Elevation Increment = 0.50 (ft) [STANDPIPE INFORMATION] DESCRIPTION : RECTANGULAR STAND PIPE [OUTLET STRUCTURE INFORMATION] Width = 2.50 (ft) Height = 2.50 (ft) Crest Length = 10.00 (ft) Crest Elevation = 378.00 (ft) Fraction Open Area = 1.00000 [RECTANGULAR STAND PIPE EQUATION] ORIFICE EQ: Q = Co*A(2gh) ^0.5 WEIR EQ: Q = Cw*L*H^exp Coefficient Co = 0.60000 Coefficient Cw = 3 .33000 Exponential = 1.50000 [DEFINITIONS] H = Headwater depth, (ft) A = Wetted area, (sqft) L = Crest length, (ft) [ORIFICE INFORMATION] SUBRECORD : 1 DESCRIPTION : EXTENDED DETENTION LOW FLOW ORIFICE [OUTLET STRUCTURE INFORMATION] Radius = 0.12500 (ft) Invert Elevation = 370.20001 (ft) Coefficient Co = 0.60000 # of Openings = 1 [CIRCULAR ORIFICE EQUATION] Q = N*Co*A* [2gh] /k] ^0.5 A = Wetted area, (sqft) h = Centroid of Wetted area, (ft) N = number of openings K = 1 49 10/22/97 Page 2 OUTLET STRUCTURE REPORT RECORD NUMBER : 4 TYPE : STAND PIPE WEIR DESCRIPTION : POND 1_ RELEASE STRUCTURE [ORIFICE INFORMATION] SUBRECORD : 2 DESCRIPTION : ORIFICE FROM SEDIMENT BASIN CONV [OUTLET STRUCTURE INFORMATION] Radius = 0 .50000 (ft) Invert Elevation = 376 .00000 (ft) Coefficient Co = 0 .60000 # of Openings = 1 [CIRCULAR ORIFICE EQUATION] Q = N*Co*A* [2gh] /k] ^0.5 A = Wetted area, (sqft) h = Centroid of Wetted area, (ft) N = number of openings K = 1 [CULVERT INFORMATION] DESCRIPTION : CIRCULAR CONCRETE/sq edge/headwall [OUTLET STRUCTURE INFORMATION] Circular Radius = 1.00000 (ft) Culvert Length = 56 .00000 (ft) Culvert Invert Elevation = 370.00000 (ft) Slope = 0.00890 (ft/ft) Manning's n-value = 0.01300 Entrance Loss Coefficient = 0 .50000 Tailwater Elevation = 0.00000 (ft) Number of barrels = 1 [UNSUBMERGED EQUATION] H/Diam = Hc/Diam + K * (Q/A*Diam^0. 5) ) ^M - 0 .5*S^2 Coefficient K = 0.00980 coefficient M = 2 .00000 [SUBMERGED EQUATION] H/Diam = c* (Q/ (A*Diam^0.5) ) ^Z + Y - 0.5*S^2 Coefficient c = 0 .03980 Coefficient Y = 0 .67000 10/22/97 Page 3 50 OUTLET STRUCTURE REPORT RECORD NUMBER : 4 TYPE : STAND PIPE WEIR DESCRIPTION : POND 1 RELEASE STRUCTURE [DEFINITIONS] H = Headwater depth, (ft) Diam = Interior height of culvert barrel, (ft) He = Specific head at critical depth (dc + Vc^2/2g) , (ft) Q = Discharge, (cfs) A = Full cross sectional area of culvert barrel, (sqft) S = Culvert barrel slope, (ft/ft) 10/22/97 Page 1 OUTLET STRUCTURE REPORT RECORD NUMBER : 2 TYPE : STAND PIPE WEIR DESCRIPTION : PROPOSED POND 2A RELEASE STRUCTURE [RATING CURVE LIMIT] Minimum Elevation = 413 .75 (ft) Maximum Elevation = 424.00 (ft) Elevation Increment = 0.50 (ft) [STANDPIPE INFORMATION] DESCRIPTION : RECTANGULAR STAND PIPE [OUTLET STRUCTURE INFORMATION] Width = 2.50 (ft) Height = 2.50 (ft) Crest Length = 10.00 (ft) Crest Elevation = 421.50 (ft) Fraction Open Area = 1.00000 [RECTANGULAR STAND PIPE EQUATION] ORIFICE EQ: Q = Co*A(2gh) ^0.5 WEIR EQ: Q = Cw*L*H^exp Coefficient Co = 0.60000 Coefficient Cw = 3 .33000 Exponential = 1.50000 [DEFINITIONS] H = Headwater depth, (ft) A = Wetted area, (sqft) L = Crest length, (ft) [ORIFICE INFORMATION] SUBRECORD : 1 DESCRIPTION : WATER QUALITY LOW FLOW ORIFICE 51 [OUTLET STRUCTURE INFORMATION] Radius = 0.12500 (ft) Invert Elevation = 414.00000 (ft) Coefficient Co = 0.60000 # of Openings = 1 [CIRCULAR ORIFICE EQUATION] Q = N*Co*A* [2gh] /k] ^0.5 A = Wetted area, (sqft) h = Centroid of Wetted area, (ft) N = number of openings K = 1 10/22/97 Page 2 OUTLET STRUCTURE REPORT RECORD NUMBER : 2 TYPE : STAND PIPE WEIR DESCRIPTION : PROPOSED POND 2A RELEASE STRUCTURE [CULVERT INFORMATION] DESCRIPTION : CIRCULAR CONCRETE/sq edge/headwall [OUTLET STRUCTURE INFORMATION] Circular Radius = 1.00000 (ft) Culvert Length = 83 .50000 (ft) Culvert Invert Elevation = 413 .79999 (ft) Slope = 0.09340 (ft/ft) Manning's n-value = 0.01300 Entrance Loss Coefficient = 0.50000 Tailwater Elevation = 0.00000 (ft) Number of barrels = 1 [UNSUBMERGED EQUATION] H/Diam = He/Diam + K * (Q/A*Diam^0.5) ) ^M - 0.5*S^2 Coefficient K = 0.00980 coefficient M = 2.00000 [SUBMERGED EQUATION] H/Diam = c* (Q/ (A*Diam^0.5) ) ^Z + Y - 0.5*S^2 Coefficient c = 0.03980 Coefficient Y = 0.67000 [DEFINITIONS] H = Headwater depth, (ft) Diam = Interior height of culvert barrel, (ft) He = Specific head at critical depth (dc + Vc^2/2g) , (ft) Q = Discharge, (cfs) A = Full cross sectional area of culvert barrel, (sqft) S = Culvert barrel slope, (ft/ft) 52 10/22/97 Page 1 OUTLET STRUCTURE REPORT RECORD NUMBER : 1 TYPE : CIRCULAR CONCRETE w/ groove end projecting DESCRIPTION : EXISTING WESTMINSTER RELEASE STRUCTURE [RATING CURVE LIMIT] Minimum Elevation = 428 .50 (ft) Maximum Elevation = 442 .00 (ft) Elevation Increment = 0.50 (ft) [OUTLET STRUCTURE INFORMATION] Circular Radius = 1. 50000 (ft) Culvert Length = 54.00000 (ft) Culvert Invert Elevation = 428.50000 (ft) Slope = 0.01000 (ft/ft) Manning's n-value = 0.01300 Entrance Loss Coefficient = 0.50000 Tailwater Elevation = 0.00000 (ft) Number of barrels = 1 [UNSUBMERGED EQUATION] H/Diam = He/Diam + K * (Q/A*Diam^0.5) ) ^M - 0.5*S^2 Coefficient K = 0.00450 coefficient M = 2 .00000 [SUBMERGED EQUATION] H/Diam = c* (Q/ (A*Diam^0 .5) ) ^Z + Y - 0.5*S^2 Coefficient c = 0.03170 Coefficient Y = 0.69000 [DEFINITIONS] H = Headwater depth, (ft) Diam = Interior height of culvert barrel, (ft) He = Specific head at critical depth (dc + Vc^2/2g) , (ft) Q = Discharge, (cfs) A = Full cross sectional area of culvert barrel, (sqft) S = Culvert barrel slope, (ft/ft) 53 a MISCELLANEOUS DESIGN CHARTS AND EXHIBITS A'IEJ McKEE/CARSON CONSULTING ENGINEERS•LANDSCAPE ARCHITECTS•PLANNERS QUEEN CHARLOTTE SQUARE 301 EAST HIGH STREET CHARLOTTESVILLE,VIRGINIA 22901 (804)979 7522 21 OCTOBER, 1997 6 72 1992 TABLE 5-2 VALUES OF RUNOFF COEFFICIENT (C) FOR RATIONAL FORMULA Lint t „ C Land Use C . Business: Lawns: Downtown areas 0.70-0.95 Sandy soil, flat, 2% 0 05-0.10 Neighborhood areas b 0.50-0.70 Sandy soil, average, 2-7% 0.10-0.15 "l Sandy soil, steep, 7% 0.15-0.20 4. Heavy soil, flat, 2%, 0.13-0.17 Heavy soil, average, 2-7% 0.18-0.22 Heavy soil, steep, 7%, 0.25-0.35 ; Residential: Agricultural land: • Single-family areas 0 30-0.50 Bare packed soil r:. Multi units, detached 0.40-0.60 * Smooth 0.30-0.60 Multi units, attached 0.60-0.75 * Rough 0.20-0.50 Suburban 0.25-0.40 Cultivated rows * Heavy soil, no crop 0.30-0.60 * Heavy soil, with crop 0.20-0.50 * Sandy soil, no crop 0.20-0.40 * Sandy soil, with crop 0.10-0.25 Pasture * Heavy soil 0.15-0.45 * Sandy soil 0.05-0.25 • Woodlands 0.05-0.25 ,`' Industrial: g/ Streets: r` Light areas 0.50-0 SO Asphaltic 0.70-0.95 it Heavy areas 0 60-0 90 Concrete 0.80-0.95 Brick 0.70-0.85 ►k ili Parks, cemeteries 0.10-0.25 Unimproved.areas 0.10-030 'f is Playgrounds 0.20-0.15 Drives and walks 0.75-0.85 • • Railroad yard areas 0.20-0.40 Roofs 0.75-0.95 • -Note: The designer must use judgement to select the appropriate "C" value within the range. Generally, larger areas with permeable soils, flat slopes and dense vegetation should have the lowest C values. Smaller areas with dense soils, moderate to steep slopes, and sparse vegetation should he assigned the highest C values. Source: American Society of Civil Engineers \' - lo 1992 TABLE 5-8 MANNING'S "n" VALUES Surface Best Good Fair Bad Uncoated cast-iron pipe 0.012 0.013 0.014 0.015 Coated cast-iron pipe 0.011 0.012* 0.013* Commercial wrought-iron pipe, black 0.012 0.013 0.014 0.015 Commercial wrought-iron pipe, 0.013 0.014 0.015 0.017 galvanized Riveted and spiral steel pipe 0.013 0.015* 0.017* Common clay drainage tile 0.011 0.012* 0.014* 0.017 Neat cement surfaces 0.010 0.011 0.012 0.013 Cement mortar surfaces 0.011 0.012 0.013* 0.015 Concrete pipe 0.012 0.013 0.015* 0.016 Concrete-lined channels 0.012 0.014* 0.016* 0.018 Cement-rubble surface 0.017 0.020 0.025 0.030 Dry-rubble surface 0.025 0.030 0.033 0.035 Canals and ditches: Earth, straight and uniform 0.017 0.020 0.225* 0.025 Rock cuts, smooth and uniform 0.025 0.030 0.033 0.035 Rock cuts, jagged and irregular 0.035 0.040 0.045 Winding sluggish canals 0.0225 0.025* 0.0275 0.030 Dredged earth channels 0.025 0.0275* 0.030 0.033 • Canals with rough stony beds, weeds on earth banks 0.025 0.030 0.035 0.040 Earth bottom, rubble sides 0.028 0.030* 0.033* 0.035 * Values commonly used in designing. Source: King V - 62 1992 TABLE 5-3 ROUGHNESS COEFFICIENTS (MANNING'S "N") FOR SHEET FLOW Surface Description nl Smooth surfaces (concrete, asphalt, gravel, or bare soil) 0.011 Fallow (no residue) 0.05 Cultivated soils: Residue cover < 20% 0.06 Residue cover > 20% 0.17 Grass: Short grass prairie 0.15 Dense grasses2 0.24 Bermudagrass 0.41 Range (natural) 0.13 Woods-: Light underbrush 0.40 Dense underbrush 0.80 1 The "n" values are a composite of information compiled by Engman (1986). 2 Includes species such as weeping lovegrass, bluegrass, buffalo grass, blue grama grass, and native grass mixtures. When selecting n, consider cover to a height of about 0.1 ft. This is the only part of the plant cover that will obstruct sheet flow. Source: USDA-SCS V - _,1) • 1992 • TABLE 5-8 (continued) MANNING'S "n" VALUES Surface Best Good Fair Bad • Natural Stream Channels: 1. Clean, straight bank, full • stage, no rifts or deep pools 0.025 0.0275 0.030 0.033 2. Same as #1, but some weeds and stones 0.030 0.033 0.035 0.040 3. Winding, some pools and shoals, clean 0.033 0.035 0.040 0.045 4. Same as #3, lower stages, more ineffective slope and sections 0.040 0.045 0.050 0.055 5. Same as #3, some weeds and stones 0.035 0.040 0.045 0.050 • 6. Same as #4, stony sections 0.045 0.050 0.055 0.060 7. Sluggish river reaches, rather weedy or with very deep pools 0.050 0.060 0.070 0.080 • 8. Very weedy reaches 0.075 0.100 0.125 0.150 • Values commonly used in designing. Source: King V - 63 4 1992 AVERAGE VELOCITIES FOR ESTIMATING TRAVEL TIME FOR SHALLOW CONCENTRATED FLOW . 50 - .... . . .- I I A ,, . ________ _ _ _,_. _- _ , ----- - -:-- - -4---, -L _._,_*_4_ _t.,,_ _ _ _ __ __,_ _ _ _ ___ . __ __ _ _ _.____ _ ,_ _____ . _ __ _ _ _ _ - __ ___, ,_ ___. - - --.--7 1 1 __ . Y 1 - _ c . 10 - ---- - , . , ' c - --- -- --'- - yl -----1 cn .06 — L ____,__ .., ____'.„._ ' ' 1 ' = •c; ,--1—:— , SI ' ' ' 1 ' . -- -r-- --'-'-•--- -. -- -•- .02 — - - _ -- - - Q - -' -- - -- - -- -- -._, — -, - - -J� � -- -- - -- - .01 — , 005 — , I I I I I I I I I I I 1 2 4 6 10 20 Average velocity (ft./sec.) Source: USDA-SCS Plate 5-2 V - I.' \ i J ) r . ` J p 40 ' A ;_. 11114 A , f / . \ ,/ /9 1.111bk• \ Uk .;14:::7)4 :ir-- _ . ,/p ', /°! / ilk - ' ilk 1/ At / - ____ .. . ri \ AllY /9: --› \ , 1 / ( -7\\ Oi/A* l'4kT ..4MIla ,leri — 20 CROSS SECTIONAL FLOW AREA 20 SF WETTED PERIMETER 20.4 FT �r HYDRAULIC RADIUS 0.98 FT 1' rI�' I,, ' 'r I-.Ii1 :�� ;, / MANNINGS n 0.23 14.,ft 1,i r, N1 I, hr 1 +,A1 ,�� „ IrsiolN 5 0 EXISTING CHANNEL GEOMETRY FOR Tc CALCULATION . r 1992 __ A �, �E NIA 1� LE COS== ___ _ __ \ . \ \- . \ • : .. . 6---,:,c-. N . . _ A- - \ \ . I - \* \\- \n\\\.\\. .. .. '' \ ' _ ._ . ___.__ __ ___ ______ ,NN ._ _. _ ._ __ _ _.____ ___ .______ \. -:_. . . ._ _________. _ _______ :_ _ ----- .�• c� - — - \.\ 100-YEAR _ --. _ -_ -- -- - .- - 5 -YEAR _- _- _ _- 2 S -YEAR - -- - - --• - __. -----• - - _- . _ --- -~.` 10-YEAR -S -YEAR x - -_-_ . 2-YEAR r i - - IDo ATICN — MiN. i 1 ---- - Source: VDOT Plate 5-8 V - 18 C DESIGN OF OUTLET PROTECTION FROM A ROUND PIPE FLOWING FULL MINIMUM TAILWATER CONDITION (Tw < 0.5 DIAMETER) - T_ ._ I � 90 H • Outlet W = Do + La A C� Pipe 2 Min. 70 __ - 1.... o �. cn 1I fee I " I Diameter, D° La _� i d� l a o �60 , p� q n• Tailwater < 0.5D0 of PQt I ' ,__, .,„,:,, ? ii 4 . . ._ • , , .� , � 20— �I'I.I-i' 1 7-2 30 -'--4 , II --1------ :-----------1-; .11.6 ...The• ' --- -- -- - --_ 1_.Filt, �I, r '‘5 / _ ir,l r, • -' 'd ‘55 w 3 . . lr .. ! Illtt r ail h! l i� ` r' 1. 1 O D l •tpi of 1 T ( • o 'oi o, 2 I{}' v a h a :eV"' /'a f�l -._. , • a •ry -Q� a _ — _i i 'tij rI �5 a � , i 1 l Recommended Min. d 12 CD • I i ' L W 3 5 10 20 50 3 100 200 500 1000 L,, Co Discharge, ft./sec. :-. 00 W 0 • I • C • ,-., 0 DESIGN OF OUTLET PROTECTION FROM A ROUND PIPE FLOWING FULL MINIMUM TAILWATER CONDITION (Tw < 0.5 DIAMETER) - N C t 3 0 I 90 C7 ' ;% D 80 i- I _ .. nOutlet W = Do + La I . --- aa Cn Pipe 2 Min. i ` - - �, Diameter, Do 1 fee" /�. I; I a� ,�� i La -yl . „ f 1 •P I a` Tailwater < 0.5D0 PQ�o°' 60 I --i a''i✓ " 1 a`O- �e�9�r 50 I I - + - k, 6,, 1ti "� / -— m i T:1 r,.',�i , ,,1 ,. 1, t ,_ ..,',. 1:0*re' _ ; : I : • -"' ' -- t r c„ . . 7! I -- • -1 •I I: • r �- , • .1 11II.t11 ._ _l t- ...- a 216��V _. - • - ' 20 -trilt �',Nr•'Ig.t ••r - --1 •--I - r" 5- d /%/ -`. ' -. 1 • I - - 10 il•l•I ,. '�' F - ! _._ 1 ‘O° -..rh to a4, N ufem, i . iif .__- _1-' * r' ut gill, .'t t ' t' _ _� i •,I •I •.: 1 . `j.,... .: I', . b t . ' ya. b_ �(0'7: 2 a, O 71 t:E4tIt 1 1 111 4i; • 1 • 1 1 1 ..I•., ., ,i 0 1 • ,4_..-_- v1 , 1,j tti...k f k.. ii.;;I:: .`- -1 . . I • , . j .� :: �1 .Zl I +f►t } ++� �`? ill", 1111 ill .! �: I '�� --'ti° a'' ,° ii �-, -. ' ill - . .%_. _til14; '1{.tit; t1!t 1 r 1I t 1 . ,. . ,a 101 . I ' I ` - 1 �cp n tt�1t, 1 I, It• 1, ,t l 11 11I' I , t t )5 a 1 pi . i '� , _ . }. , Recommended Min. .j!1 ;f. 11, 'n •I'1 ' '', CHI " 12 , 0 1 i 1 1 w ,-, 3 5 10 20 50 3 100 200 500 1000 �,, co Discharge, ft./sec. W CC �� T 1 -. 4 a - Ie0 10,000 CHART 2 •- 166 - e,000 EXAMPLE (1 ) (2) (3) — 6. - 156 - 6,000 0••! Iola,' st)MB fa - 5,000 13020 sfs ' - 144 '- . - 4,000 • Itr 6. - '- S. - 132 - f..+ 4. 120 3,000 (11 !.s �.s S' - 4. (2) 2.1 T.• - - Ice - 2,000 (3) !.! 7.1 4. - 3. '0Infoe - "_ 3. - 96 - 1,000 - 3. - ` - - Soo - -• —-_-r- - 94 - - 600 - /� - . 2. `2 — goo / - - - 72 - 400 `` 3 - 2. In / - - i 300 +j - I.s - 1.3 u Z to . 1Z -r _ - 60 u _- 200 - 1.5 ` - Z - / W _ ` o - 34 i - O r . _ cc /W — 100 Z F J � 4e / Q - 60 = D / _ — 1- - u =42 0 - 60 W - 1.0 _ 1.0 O 0 - SO HW SCALE ENTRANCE 0 1.0 - - - 40 0 TYPEcc- W W- — 36 - 30 (I) Sq..r.wqs with .9 - .9 - .9 i - h..HNI p - 33 Irar — 20 It) flr.•Ies Sad 11 4 0 W -. - 30 II«Nall = .e .e 13) Groovy sad .e prs(.atlaq ' - L7 - 10 ` -_' r .7 - t4 - e - .7 - 6 Ts ••ss .gels (!) If (3) .rs)sst - - S n.rlt.ntelly Is seals (1),tll.a - - 21 - - 4 •s• slrsli t 1•clln.. 11.e tMwilt 0 lad 0 •ales,.r ss OS . .6 3 Illr.lr . - .6 le 2 _ ` - IS 1.0 - .5 'S .S - I= HEADWATER DEPTH FOR ►,EAowArer SCALES zee CONCRETE PIPE CULVERTS IEwSED MAY 1964 WITH INLET CONTROL .u.(4u Of►v.LIC ROADS atw. Hu 22 (5-22 ) I44. le > U, • z r) SECn O/v- LAC/S7 . GvESTM/n/ST6e-/ g Pv D (pe7A60 2E) LL M Z re W >' W 450 W —Top of Dom z Grote 433.0 Elev 445 W W Typ7 eTop - Gro/e 440. 0 -I DI 7 Top Grote Type / Q j .° 4 4 0 36" RCP Inlet Ca 428. 5 430 In ES-/ �, ` , B ' 95 , B7% 36 '� Rc�� ' 541 Gv /.0 %r ;MH 420 Sta. /t 39 Out/et /NH Sto. Ot 44 Inv. 427 96 422.0 In/et 425. 23 Slo. Or2/ /nv. 422. 23 0 o 0 Ot30 Or60 0r90 /.?, I.Sn /. e., 2. .n J Jf_ .3 rt - - -- _.--' �- /-1 / / J - - / /yl , m -- - - - - f.� i / • _ _ __ \ \�.1� - - --- _ — — __ ,�• — —ice — / �/' LL _ \ ` �'` — — — — — — —— - — — — —� / / / 7