FAIRFAX MANUAL...FAIRFAX COUNTY PUBLIC FACILITIES MANUAL H (Ft. 500 Tc minutes 400 200 EXAMPLE...

FAIRFAX COUNTY PUBLIC FACILITIES MANUAL

Ref. Sec. 6-0205,6-0202.8 PLATE NO. STD. NO.SMALL PRIVATEDRAINAGE SYSTEM 1-6

Rev. 1-00, 2-06, 2011Reprint. 2018 Reprint


Rainfall Intensity (in/hr)

Frequency 1-year 2-year 5-year 10-year 25-year 50-year 100-year

Duration5 minutes10 minutes15 minutes30 minutes1 hour2 hours3 hours6 hours12 hours24 hours

4.26 5.23 6.06 6.77 7.69 8.39 9.103.40 4.19 4.89 5.45 6.15 6.76 7.282.83 3.51 4.13 4.62 5.22 5.77 6.221.94 2.41 2.88 3.26 3.73 4.20 4.571.21 1.53 1.87 2.16 2.54 2.93 3.25

0.7110.5070.3120.1890.109

0.8680.6170.3790.2280.132

1.10 1.28 1.54 1.75 1.970.7830.4790.2890.170

0.9150.5600.3420.203

1.10 1.26 1.430.6820.4210.254

0.7850.4910.299

0.8970.5690.351

NOTES:1. VDOT equations (Fairfax County B, D & E values) were used to generate rainfallintensities for storm durations from 5 minutes to 1 hour for the 2, 5, 10, 25, 50 & 100-year storms.2. NOAA Atlas 14 data for the Vienna/Tysons station was used for storm durationsgreater than 1 hour.3. NOAA Atlas 14 data for the Vienna/Tysons station was used for the 1-yr storm.VDOT never performed a regression analysis of the NOAA Atlas 14 data for the 1-year storm.4. The VDOT equations although developed from a regression analysis ofNOAAAtlas 14 data will not yield exacly the same values as the published NOAA Atlas 14data for the 5, 10, 15, 30 & 60-minute durations because of the curve fitting process.

Ref. Sec. 6-0803.3&STD. NO.PLATE NO.

INTENSITY DURATION FREQUENCYVALUES 32B-6

Rev. 1-00, 2011 Reprint,2-16, 2018 Reprint


H (Ft. )500

Tc minutes200400

EXAMPLEHeight = 100*

Length = 3,000*

Time of concentration

300 150

14 minutes200100

150H 80wHjH L (Ft. )

I=— 10,000100a 60o

50w>o 40PQ< &50 o5,000H 30£HH

40 H25o aHjPL. w H30 > £3,000 20W wH PS CJNote:

Use nomograph Tc for natural basins with welldefined channels, for overland flow on bareearth, and for mowed grass roadside channels.

For overland flow, grassed surfaces, multiplyTc by 2.

For overland flow, concrete or asphalt surfaces,multiply T by 0.4.

For concrete channels, multiply T c by 0.2.

o H £a 20 152,000 o.pHw oPH oPH1,500aH oCD H 10o o wa £ aHH10 8w 1,000 Ho aa 6a a

HHo 5500535wa a 44300

3 3

2002 2150

100

11

Ref. Sec. 6-0803.34C(l ),6 1011, Table 6.11 PLATE NO. STD. NO.TIME OF CONCENTRATION OF

SMALL DRAINAGE BASINS 43-6Rev. 1-00, 2011 Reprint,2018 Reprint


Ref. Sec. 6-0804.82,6 0804.6B(2), 6-0804.7 PLATE NO . STD. NO.FLOOD FREQUENCY CURVES

FOR SELECTED DEGREES OFBASIN IMPERVIOUSNESS £5-6Rev. 1-00, 2011

Reprint, 2018 Reprint


Ref. Sec 6-0804.65,6 0804.6B(5), 6-0804.7 LAG TIME

AS A FUNCTION OFA LENGTH-SLOPE INDEX

PLATE NO . STD. NO.

Y6-6Rev. 1-00, 2011 Reprint*2018 Reprint


r 1000-900- 800- 700L 600- 500

1

-400

- 300

2- 200

120108

98 - .00029084- 100

-90-80- 70- 60- 50

- .0003- .0004

78- 372

66co co - .0006- .0008- .0010

w 60£ oo 54 o£ II

48 - 4xn 2;HH 42 Q- 40o o £39i— i

- .0020 oaHH 36< uwK-30 - .0030

-<0040w33 OH - 5Q COw oo 30

COo w27COHa - .0060

- .0080- .0100

- 20 a - 6o 24 HWCO H W21Q W wa - 7< 18 £iQ - .0200- 10 £

HH

- 815- 9 - .0300

- .0400u- 8 o - 912- 7 w>- .0600

- .0800- .1000

- 10- 610

- 5 - 11- 128- 4

13- 3 146

15

- 2 Example: Given discharge Qfriction factor nslope of 0.0045

Find: Required diameter of pipe and velocity of flow.From Nomograph, extend dashed line from dischargeof 4.4, thru slope of .0045, Diameter = 15” , and velocityequals 3.5 FPS.

4.4 CFS0.013

- 1- 0.9*— 0.8

Ref. Sec. 6-0902.2 STD. NO.PLATE NO.NOMOGRAPH FOR COMPUTINGREQUIRED SIZE OF CIRCULAR

DRAIN, FLOWING FULL 87-6Rev. 1-00. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALProposed pierat nearest joint-each side.

Proposed Stormsewer

6”1 1I I.

8”mm.

RRIRIRIRI -IIRIRII— Ill-Ill

Proposed pier to be builton undisturbed earth.Concrete to be class *A’ AE.

8”

16” min.( typical )Sanitary

Sewer

StormSewer

2”2” min.min.

Proposedpier

• A'.4.<

' 4' 4 ,

* •

4_

A -4- 44

8 ” mm.*4.4 .- 44.:* •

\4

SanitarySewer

Ref. Sec. 6-0902PLATE NO. STD. NO.CONCRETE PIER FOR

STORM SEWER PIPE DPW-26FT8-6Rev. 1-00. 2018 Reprint


Rounded(r open channel - proposed

Existing ground

Sodde

— Selected fill to be compactedto a minimum dry density of 95%of the maximum dry density.t=12” gabions

Permeable membra:

TYPICAL CHANNEL SECTION

dimensions to be at least 1§ times the depth of anticipated scour in the channel.X =n = (roughness coefficient) = 0.028

Use permeable membrane (synthetic fiber or 4” - 6” gravel layer) if bank materialis fine sand or silt to prevent leaching.Thickness of gabions: t = 12” when alignment of channel is straight, side slopesthan 30° and velocity is less than 10 FPS. t = 18” for curved alignment, side slopesof 30° to 45° and velocities 10 TO 15 FPS.

are less

Gabion baskets should be filled while under tension to assure better alignment and compaction.

Gabions will be made with galvanized steel wire triple-twisted mesh; the wire meeting Federalspecification QQ-W-461F Class 3, and the galvanizing being finish 5, class 3 ( 0.80 oz./SF ).A polyvinyl coating is required on the galvanized wire when used under highly corrosiveconditions (pH greater than 11).

Ref. Sec. 6-1011.1U6 1002, 6 1012.1V GABIONS-

TYPICAL SECTIONOPEN CHANNEL

PLATE NO. STD. NO.

211-6 GB-1Rev. 1-00, 2011 Reprint*2018 Reprint


2H Min. Grouting of weir notch is recommended aftersettlement to protect wire mesh from abrasion.

V Y Y I I

Counter-weir creates stilling pool whichdissipates energy of falling water thuseliminating undercutting of weir.’H’ should be limited to 3’ max. if possible

H

^-ww^ 1

Ref. Sec. 6-1011.1U6 1002, 6 1012.1V PLATE NO. STD. NO.GABIONS - TYPICAL

SECTION WEIR GB-32313-6Rev. 1-00, 2011 Reprint*2018 Reprint


z

Horizontal datum

Z = Distance above horizontal datum

D = Depth of flow

V8

= Velocity head2g

hf = Friction loss between section 1 and 2

EGL = Energy grade line

HGL = Hydraulic grade line

Ref. Sec. 6-1006 6 1007PLATE NO. STD. NO.

OPEN CHANNEL 2414-6Rev. 1-00. 2018 Reprint


HL

v!

Transition and/orhorizontal curve

Zi - Zg = ( D2 -DJ + (|L _ vl_ ) + HLH^= h^ + h2 + hf

Zi ,Z2 = Incoming and outgoing channel inverts

D I ,D 2 = Depth of flow in incoming and outgoing channels

vf vi Velocity head of incoming and outgoing channels2g ,2g

= Total energy loss

hx = Energy loss thru transition

h2 = Energy loss thru curve

hr = Friction loss thru transition and/or curve length, generally negligible

Ref. Sec. 6-1006.6-1006.2 6 1007.2C OPEN CHANNEL

TRANSITION AND/ORHORIZONTAL CURVE

PLATE NO. STD. NO.

£616-6Rev. 1-00, 2011 Reprint*2018 Reprint


1.0 -p 12r 10.0- 8.0

5114a

10 r 6.0- 5.0- 4.0

cn3

U-- 9£HH

CO 2- 3.08 aH aa O or 43W £l-H - 2.0 -1.5

- 7 co£ £M

oaHH o

££A A a\ A ^*v «0.5 -- 6 - 1.0

— 0.8OHo O o - 1.0CL,£ £

HH *IV o&H£- OAf£ O .9aW W oCL, P-4 a- 5 0.5o o .8H

/5? aa - 0.4a a oo o ^ a .7aH - 0.3H aa a &Ho - 4 O o a .6Oa a - 0.2Ha a o COoCL, a .5aa Ha .1v a

0.25 -^3 .08>< .4aHHU .06 aa.05a Q<iu .04 Q .3a.03 aaoa

L 2

Surface ofponded water

.2

h!# * / $ • i s. .15

Local depression (a)’*' a *

ELEVATION SECTION

* ” a” identifies local depression dimensions for DI-3A, B and C

Ref. Sec. 6-1102.13.6-1103.1 6 1103.12,6 1104.1

STD. NO.CAPACITY OF CURB INLETSAND YARD INLETS ATLOW POINT IN GRADE

PLATE NO.

THT20 6Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALStandard 3/8” X 3” X 4”angle iron with 2 anchor bars(see Plate 22-6 33-6)

1/2” deformed bar5* — 0” long

4* — 0”inside dimension

H deformedanchor bars —

»

dimension

1/2” deformed bar2’— 6” long

1/2” deformedanchor bars Standard 3/8” X 3” X 4” angle iron

angle iron with 2 anchor bars

Bottom of rods to be1” from bottom of slab4”

\ •V.' i •-v' -V "A. -V4” Class A3 —concrete slab

Standard angleironOpen throat 6”

cheekblock — For concrete apron

see Plate 22-6 33-6detail

Os Standardmanhole _steps -— VariesVaries

Standard curbinlet block£Slope invert to outlet

, -V-•: -i; L. A

6”**4

— I SECTION A - AYard inlets deeper than 4*-0” shall must have steps placed as shown.

Dimensions of yard inlets shown are for pipe sizes up to and including 33” pipe, while providing aminimum of 6” clearance when possible from inside wall of structure to 0D of pipe. Inlets for pipesgreater than 36” shall require a special design.Symmetrical channels shall must be formed in the invert of the box from the inlet pipe to the outletpipe.Increase the horizontal depth and pave invert of yard inlets for skewed pipe as directed by theinspector.Provide 3/8” x 3” x 4” angle iron for full length of throat unless it is precast. The 4” flange of angleiron shall must be vertical and showing on face of yard inlet. Angle iron shall must be painted withblack asphaltum paint.

The inside and outside walls, as they are laid, shall must be plastered with mortar a minimum of 1/2”thick when construction of block.

Ref. Sec. 6-1103.41104.4 STD. NO.PLATE NO.STANDARD YARD

INLET YI-l821-6Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALALTERNATESTEP DETAIL\<s\ Concrete

wingwall\/\ r-B 3/4”\/ \ H. hr7 3/4”\ / \\ // \V K i

\

'/ A 5”9”>1CO T

irA

/ i i f lVariable\ / — 1 -r AB T , EB-B 3/4”

h— 7"-H4* — 0”

. Y////& 2”

£ - -— 1/2”1-1/4”

YARD INLET 18” A-Amin.TOP

ApronANCHOR BAR DETAIL

\ Variable PLAN\\\\ 1£ X )\

\ Angleiron ^ u r\ /\\

Concretewingwall- \ / 16”\

\ Weld here\4I\

M/2” deformedanchor bar

STEP DETAILConcrete slab (typical)\ 18” min.

4”6”11- — l/4” :l *

LT12 mm.Concrete apron 6”

v t12” dowels 12” CC Apron slab 1structure wall— 6”

Note: The concrete apron may be poured-in-place orprecast.Note: Concrete aprons to be built on all yard inlets.Reinforcing shall must be 6” x 6” No. 6 wire mesh.All concrete shatt must be Class A3. Length of apronmay be increased to 36” if field conditions warrant.Note: When aprons are on adjacent sides of inlet, theadjoining wingwalls will be omitted and apron shallmust have 1.5* radius. When inlet is larger than 5.0’x 5.0’, opposite concrete aprons shall must be builton centerline of inlet; 2 adjacent aprons shall mustbe built adjoining the common corner; and if thereare 3 or 4 concrete aprons on 1 inlet, then allaprons shall: must be built on centerline of inlet.

Step to extend 5” frominside face of manhole wall.No. 6 galvanized Steel baror No. 3 reinforcing rodcompletely encased in acorrosion resistant rubber,or other material approvedby the Director.Detail shown is for minimumstep design. Alternates ofequal or greater strengthwill be acceptable.

Ref. Sec. 6-1103.4.6 1104.4, Plate 21-632-6

STD. NO.PLATE NO.TYPICAL CONCRETE APRON

FOR YARD INLETS 3322-6 YI-1Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint


Hw 10.0w T T T T T T9.0 (B>Curve8.0£H-I 7.0

Curb 6.0HH 5.0P5O 4.005Width (B) /w> 3.0 /o05 2.0w

“ H Length (1^) ^- H<3

Usecurve (B) for

^epth over gratemore than 0.8 Ft

1.5o1.02B+LbA = Area of clear opening in grate

to allow for clogging divide P orA by 2 before obtaining d.without curb P = 2(B+Lb)

P 0.91 I L L I0.8a 3 4 5 6 7 8910 15 20H

OHWQ

DISCHARGE PER FT2 OFEFFECTIVE CLEAR OPENING

0.8 I I I ICurve (A)

T T T T T T T0.6

HW 0.4w

£HH

wEH

0.2<105005W>O 0.105WEH

Use curve (A) for depth overgrate less than 0.8 Fto

a 1 1 1 1 1 1EHOHWP 0.1 0.15 0.2 0.3 0.4 0.60.81.01.5 2.0 3.0

DISCHARGE PER FOOT OF EFFECTIVE PERIMETER

Ref. Sec. 6-1105.16 1106 STD. NO.HYDRAULIC CAPACITY

OF GRATEINLET IN SUMP

PLATE NO.

3625-6Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint


3’

NOTICEl3” LETTERSA STORMWATER

FACILITY WILL BELOCATED AT THIS SITE

SEE CONSTRUCTIONPLAN FOR DETAILSOR CALL XXX-XXXX

r— 2.5” LETTER3’

5/8” BORDER

••J1/2

Sign to be of aluminum, flat blank, 0.08”thickness.Letters and border white, background blue.Phone number is of the Site Development Plan

and Inspections Division, LDS DPWES.(Current number is 703-324-7470 324-1950, verify)

Note: 1.2.3.

Ref. Sec. 6-1305.7FPLATE NO . STD. NO .

NOTICE OF LOCATION OFSTORMWATER FACILITY 4UB28-6 SW-1Rev. 1-00, 2011 Reprint*2018 Reprint


/

Horizontal

V?/ 2gH EGLL

DiHGLVl2g

invertD2 Stream

Z2 Horizontaldatum

L

Z 2, Z 2

D 2, D2V 2, v2

L> , 22 g, 2 g

Distance to upstream and downstream inverts

Upstream and downstream depths of flow

Upstream and downstream velocity head

HL = Energy loss between upstream and downstream sections

L Distance between upstream and downstream sections

Ref. Sec. 6-1403,6-1403.2 PLATE NO. STD. NO.

FLOODPLAIN 4529-6Rev. 1-00. 2018 Reprint


50

2.5 (100 Yr.)45

Dam height 25 Ft. & impoundmentCapacity 15 Ac-Ft andDam height 6 Ft. Sc impoundment~Capacity^ 50 Ac-Ft areRegulated by DCR Sc the County- ~

40iZi.i/

i/1 U_LLL/ l J2

IX.L.LI I-P

w 35 iL-PAB 30

a ii 4/c6

Q 25 & LL100 Yr. I A20

I I

I /HB 3!3315 2f- 2.5 (100 Yr.)'II

II10 Y /---7n AzAL

I I I LI I LI6 4-5

100 Yr.ii

0LOiO0 o o o oO ^ o w o o ooo o o o CM COCM CO lO CD CO 05

Impoundment Capacity ( Ac-Ft )

24 Hr. = 8.41” ( Ref: NWS N0AA Atlas 14 )100 YrPMP, 24 Hr. = 35.5” ( Ref: NWS HMR-51 )

•>

Design Storm Ranking*100 Yr. = 0.2 PMP

1.5 X (100 Yr.) =2.5 X (100 Yr.3.5 X (100 Yr.5.0 X (100 Yr.)

0.3 PMP0.5 PMP0.7 PMP1.0 PMP

* The above ranking shall must be used when selecting’Next Highest Storm’ for freeboard hydrograph.

Ref. Sec. 6-1603.1A,6— 1603.IB, 6— 1603.4B,6— 1603.4E, 6 1601.1 24 HOUR DESIGN STORM

CHART FOR SPILLWAY DESIGNFLOOD (SDF)

STD. NO.PLATE NO.

4030-6Rev. 1-00, 1-04, 2011Reprint, 2-16. 2018Reprint


Time(hour)

Cum.Precip.

Incre.Precip.

Cum.Precip.

Time(hour)

Cum.Precip.

Time(hour)

Incre.Precip.

Cum.Precip.

Incre.Precip.

Time(hour)

Incre.Precip.

(%)(%) (%)(%) (%) (%)(%) (%)

0.0 6.0 9.0 14.6050.000 3.0 0.131 3.528 0.161 7.925 0.2810.0000.1 0.128 3.1 0.132 0.165 8.090 0.2950.128 3.660 6.1 9.1 14.9000.2 0.231 3.2 0.133 3.793 6.2 0.169 8.259 9.2 0.310 15.2100.1030.3 0.335 9.33.3 0.134 3.927 6.3 0.173 8.432 0.326 15.5360.104

3.4 0.135 4.062 6.4 0.177 8.609 0.340 15.8760.106 0.441 9.40.40.5 0.547 3.5 0.137 4.199 6.5 0.181 8.790 9.5 0.355 16.2310.106

0.107 0.654 6.6 0.185 9.6 0.3710.6 3.6 0.137 4.336 8.975 16.6020.7 0.109 0.763 3.7 0.138 4.474 6.7 0.189 9.164 0.385 16.9879.70.8 0.109 0.872 3.8 0.139 4.613 6.8 0.192 9.356 9.8 0.400 17.387

9.5530.9 0.110 0.982 3.9 0.140 4.753 6.9 0.197 9.9 0.416 17.8031.0 1.093 4.0 0.141 4.894 7.0 0.201 9.754 10.0 0.430 18.2330.111

0.113 1.206 4.1 0.142 5.036 7.1 0.205 9.959 10.1 0.4451.1 18.6781.2 0.209 10.2 0.461 19.1390.113 1.319 4.2 0.143 5.179 7.2 10.1681.3 0.114 1.433 4.3 0.145 5.324 7.3 0.212 10.380 10.3 0.475 19.614

0.115 1.548 4.4 0.145 5.469 7.4 0.217 10.597 10.4 0.490 20.1041.41.5 1.665 10.818 10.5 0.506 20.6100.117 4.5 0.146 5.615 7.5 0.2211.6 1.782 4.6 0.147 5.762 7.6 0.224 11.042 10.6 0.563 21.1730.1171.7 4.7 0.148 5.910 0.6200.118 1.900 7.7 0.229 11.271 10.7 21.793

22.4721.8 2.019 7.8 10.80.119 4.8 0.149 6.059 0.232 11.503 0.6781.9 0.121 2.140 4.9 0.150 6.209 7.9 0.237 11.740 10.9 0.735 23.206

8.0 11.981 11.02.0 0.121 2.261 5.0 0.151 6.360 0.241 0.793 23.9992.1 0.122 2.383 5.1 0.152 6.512 8.1 0.244 12.225 0.90011.1 24.899

8.2 25.9072.2 0.123 2.506 5.2 0.153 6.665 0.249 12.474 11.2 1.0082.3 5.3 0.154 6.819 8.3 11.3 1.1150.125 2.631 0.252 12.726 27.0222.4 0.125 2.756 5.4 0.155 8.4 0.256 12.982 1.2236.974 11.4 28.2452.5 29.5500.126 2.882 5.5 0.156 7.130 8.5 0.261 13.243 11.5 1.305

3.009 5.6 0.157 7.287 31.5722.6 0.127 8.6 0.264 13.507 11.6 2.0222.1282.7 0.128 3.137 5.7 0.158 7.445 8.7 0.269 13.776 11.7 33.700

2.8 0.130 3.267 5.8 0.159 7.604 8.8 0.272 14.048 11.8 2.918 36.6180.130 11.92.9 3.397 5.9 0.160 7.764 8.9 0.276 14.324 4.051 40.669

Source: N0AA C Rainfall Distribution

Ref. Sec. 6-08021,6—1603.1A, 6—1603.2E STD. NO.PLATE NO.24 HOUR

RAINFALL DISTRIBUTION 4Y31A — eRev. 1-00, 2011Reprint, 2-16. 2018Reprint


Time(hour)

Cum.Precip.

Incre.Precip.

Cum.Precip.

Time(hour)

Cum.Precip.

Time(hour)

Incre.Precip.

Cum.Precip.

Incre.Precip.

Time(hour)

Incre.Precip.

(%)(%) (%)(%) (%) (%)(%) (%)

12.0 18.0 21.0 96.47247.660 15.0 0.295 85.395 0.165 92.075 0.1326.99112.1 59.331 15.1 0.281 0.161 92.236 0.13111.671 85.676 18.1 21.1 96.60312.2 63.382 15.2 0.276 85.952 18.2 0.160 92.396 21.2 0.130 96.7334.05112.3 66.300 21.315.3 0.272 86.224 18.3 0.159 92.555 0.130 96.8632.918

15.4 0.269 86.493 18.4 0.158 0.128 96.9912.128 68.428 92.713 21.412.412.5 70.450 15.5 0.264 86.757 18.5 0.157 92.870 21.5 0.127 97.1182.022

1.305 71.755 18.6 0.156 21.6 0.12612.6 15.6 0.261 87.018 93.026 97.24412.7 1.223 72.978 15.7 0.256 87.274 18.7 0.155 93.181 0.125 97.36921.712.8 1.115 74.093 15.8 0.252 87.526 18.8 0.154 93.335 21.8 0.125 97.494

93.48812.9 1.008 75.101 15.9 0.249 87.775 18.9 0.153 21.9 0.123 97.61713.0 76.001 16.0 0.244 88.019 19.0 0.152 93.640 22.0 0.122 97.7390.90013.1 0.793 76.794 16.1 0.241 88.260 19.1 0.151 22.1 0.12193.791 97.86013.2 0.150 22.2 0.121 97.9810.735 77.529 16.2 0.237 88.497 19.2 93.94113.3 0.678 78.207 16.3 0.232 88.729 19.3 0.149 94.090 22.3 0.119 98.10013.4 0.620 78.827 16.4 0.229 88.958 19.4 0.148 94.238 22.4 0.118 98.21813.5 79.390 94.385 22.5 0.117 98.3350.563 16.5 0.224 89.182 19.5 0.14713.6 79.896 16.6 0.221 89.403 19.6 0.146 94.531 22.6 0.117 98.4520.50613.7 16.7 0.217 89.620 0.1150.490 80.386 19.7 0.145 94.676 22.7 98.567

98.68113.8 80.861 19.8 22.80.475 16.8 0.212 89.832 0.145 94.821 0.11413.9 0.461 81.322 16.9 0.209 90.041 19.9 0.143 94.964 22.9 0.113 98.794

20.0 95.106 23.014.0 0.445 81.767 17.0 0.205 90.246 0.142 0.113 98.9070.430 82.197 17.1 0.201 90.447 20.1 0.141 95.247 23.1 0.11114.1 99.018

20.2 99.12814.2 0.416 82.613 17.2 0.197 90.644 0.140 95.387 23.2 0.11014.3 17.3 0.192 90.836 20.3 23.3 0.1090.400 83.013 0.139 95.526 99.237

0.385 83.398 17.4 0.189 20.4 0.138 95.664 23.4 0.10914.4 91.025 99.34614.5 99.4530.371 83.769 17.5 0.185 91.210 20.5 0.137 95.801 23.5 0.107

84.124 17.6 0.181 91.391 99.55914.6 0.355 20.6 0.137 95.938 23.6 0.1060.10614.7 0.340 84.464 17.7 0.177 91.568 20.7 0.135 96.073 23.7 99.665

14.8 0.326 84.790 17.8 0.173 91.741 20.8 0.134 96.207 23.8 0.104 99.7690.310 23.914.9 85.100 17.9 0.169 91.910 20.9 0.133 96.340 0.103 99.872

24.0 0.128 100.000

Source: N0AA C Rainfall Distribution

Ref. Sec. 6-08021,6—1603.1A, 6—1603.2E STD. NO.PLATE NO.24 HOUR

RAINFALL DISTRIBUTION L?31B-eRev. 1-00, 2011Reprint, 2-16. 2018Reprint


CM

OCM

£oH u

PQ

PH waMHHCO

Q

hJ CMCpH£<! aPH o

-P0PH"PH— oo P-po CO

Q

cd«MCxi"PHctf«p2onCM

OI

3o ooo oo o o o

CDo CMCM OO CO o op0

( TOO* }o % ) TIVdNIVH OCD

Ref. Sec. 6—0802*1,6—1603.1A 24 HOURRAINFALL DISTRIBUTION

( HYETOGRAPH )

STD. NO.PLATE NO.

4B32-6Rev. 1-00, 2011 Reprint,2-16. 2018 Reprint

a>aa>xooc|2H

aaaaoa>oaHaa

>a>a

FAIRFAX COUNTY PUBLIC FACILITIES MANUALControl section— ( c r i t i c a l depth)

Existinggrade

V

Crest section — Ndc ss\

Existinggrade

N\

\\\

20’ \0<*1* \ V/ \(min.) % \Proposed

Grade/

s

Vegetated Emergency Spillway(Sect. ES)

Existing grade/

/

Concrete trickleditch (if required) Proposed grade

Dry Detention Pond(Sect. DP)

Existing grade

Normal poolNN

\\\ V

1’ Min. depth = 4’(6* depth desired)

2-ioz 7

% //10’ /

/S

\(min.) //\

VSafety bench1’ - 2’ deep

Proposed gradeWet Pond(Sect. WP)

Ref. Sec. 6-1604.2,6— 1604.2B(2), Plates33-6. 34-6. 40-6. 41-649 6, 50 6, 56 6, 57 6

PLATE NO. STD. NO.TYPICAL SECTIONS ATSTORMWATER MANAGEMENT

FACILITIES 5P35-6Rev. 1-00, 2011 Reprint*2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUAL1Permissible Velocities for Vegetated Spillways

Permissible Velocity 2

FPSErosion Resistant3

SoilsEasily Erodible 3

Soils

Slope of Exit Channel Slope of Exit Channel% %

0 to 5 5 thru 10 0 to 5 5 thru 10

BuffalograssKentucky bluegrassSmooth bluegrassTall fescueReed canarygrass

7 6 5 4

Sod forminggrass-legumemixtures

5 34 4

Lespedeza sericeaWeeping lovegrassYellow bluestemnative grassmixtures

3.5 3.5 2.5 2.5

iNRCS-TP-Ol

2Increase values 10% when the anticipated average use of thespillway is not more frequent than once in 50 yrs. or, 25%when the anticipated average use is not more frequent than once in100 yr.

3As defined in TR — 52

Source: NRCS TR-60 — Earth Dams and Reservoirs, October 1985

Ref. Sec. 6-1604.2B(4) STD. NO.PLATE NO.PERMISSIBLE VELOCITIES FORVEGETATED EMERGENCY

SPILLWAYS 5236-6Rev. 1-00, 2011 Reprint*2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALSpotweldrebar

Anti-vortexplate

B2” wide x 1/4”thick steelring, boltedto riser

Lockableaccess door

(Do not weldaccess doorto steel ring)Akf= JtI

l

Note: Trash RackBar Spacing -2” (min.),l *(inax.)(min. 2” barspacing does notapply near apex)

Rebar( #4-#6 )

l’-O” (typ.) -^Trash Rack Detail

l’-O” (typ. BTop View

1/2” thick steelplate ( dia. = Dr/4 )

Anti-vortex plate( 1/4” steel )

Trash rack ^77YJL XX XXDr /2(2* min.)X 772ZZ— L

/ /zz \ x xxTop of riser

T_ CMP half sectiondebris hood

open bottom, closed top)or rebar cage

Orifice(as required)

Dr /4'(1* min.)

iUi

i1“ 1

Precast risersegment with

flat top

n ni m ri

J \ i.l J J vI '6* x 18” x 1/4

, galv. plate! (4 at each joiht

n bolted to rise ')r-i/ v-»

*1 -0” I

I

I I ° I 101Precast risersegment

t I.l i.lI L _J/

Steps 1— 1 — Pi,Watertightconnection \ ,

Note: All joints betweenprecast riser segmentsshall be made watertightwith Butyl Rubber 0-RingGaskets.

\

V Watertightconnection

Do<i i

1 * / * * * 4 Ur "*1 4I ° I1 I4 4

uTTv/ I M.I1 1 1 4 < 4« 4 4 V1 4 1

v«

£» 1

H * %Precast risersegment

with base

i i4 I 44A 1 . 1 4 ** *

44 * * ^ 4t> 4 t> ^ 4

4 -41 1 1* 4 It> 1 11* *1 * „ > >

< t>

4 4 4

1 4

1 I t> 4 t> K. 4 4 i 4

* « 4 ^ ^ 4 ^ 14 b.1 » t>

4 > 1 4I

4 I * I4 1 41 44 4 t>4 t>4 t> 44 1 41 4Concrete closurepour in base tocounteract buoyancy Dr

Sect.” A — A” ” B — B”Elev.Ref. Sec. 6-1604.4,6-1604.8A, 6-1604.8E,6-1604.9

SCHEMATIC DETAIL OF PRE-CASTCIRCULAR RISER AND TRASH RACKFOR USE WITH DRY OR EXTENDED

DRY DETENTION PONDS

STD. NO.PLATE NO.

537-6Rev. 1-00. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALrStd. handrail

9*Trash rack bar spacing: 2” (min.), 1’ (max. )

Ao- <> -o-r ii r ~ r ~i ~ ~]I i i l4-A Ar i—ii — i- — i i

ii 1ii iI iI o AI I AI frame & cover I Ifor access

AAI AII I A I I— r ~i i AA? l J I I AIT I I I I II Roundedentranceat riser

i i_ _i _ J I I ^I

J4 I

&L J— I A9^ i /Plan View A

A Al~ ~ ~A~

A ^ A^ A~ 3r J

. AA ^ A

Crank operatedfloor stand Sec. B — B

AOverflowweirTrash

raclc~ X

<1 Low floworifice

l I<1 I I

12”^ A A ^ ^ A X Normal

poollevel

StepsOutletconduit

(box culvertor RC pipe)rounded at

riser entrance

*0 0

Bottom ofriser — ^ Sluice

gate~ - A^ A A ^ A ^ A ^ A^ A ^ A ^ AA

B Front ViewNote:Sluice gate application applies to wet ponds only.If riser is used for extended dry pond or dry detention,an orifice would replace the sluice gate.

Sect. A-A

Ref. Sec. 6-1604.4,6-1604.8E, 6-1604.9,Plate 39-6 55-6

SCHEMATIC DETAIL OF STANDARD CASTIN PLACE RECTANGULAR RISER AND

TRASH RACK FOR USE WITH WETOR DRY PONDS

STD. NO .PLATE NO.

5438-6Rev. 1-00, 2011 Reprint*2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUAL£

IB

Note: This detail is taken fromthe NRCS Std. Dwg. ES-150. "DropInlet Spillways- Standard forCovered Top Riser.” See ES— 150for more detail.

41 1 1 XiI

30” D (or 24” x 24”square) MHcapable of beinglocked in place(Cover not shown)

1/f.\

I

Note: For wet pond application asluice gate shall must beprovided on the inside of theriser similar to that shown onPlate 38-6 54-6.

A 99 A 994 x 4 ^fillets optionalwith contractor

i

CJ I!

, i T* * • A I I I•14- < r .’c •t + -t

Sec. A — AFooting and Spigot Wall Fitting Not Shown

6

2D4 ' T7*• . • . 4-IHF i

1/2 D gJi 6R14 4s: K6/ \

Jlear spacingnot more than

i. <

3/8 D4I\K 4\i

4

I

4 *<3 DD — 10” min.

Low stage inletas required. (May usein either endwall).

10” min - - 10”min.

10” min.X• 4

f 5

1 'I Plate construction joint(Location of other jointsdepends on height ofriser.) —

Spigot

fitting

.•4wallj-

CMI V /

/ ( / \ 4 <+ lI I \ :I I iQ nit

V l,<

Sec. B — BSec. C-C

Ref. Sec. 6-1604.4,6— 1604.8E, 6-1604.9 SCS STANDARD 2-WAY

COVERED RISER FOR USEWITH WET OR DRY PONDS

PLATE NO. STD. NO.

5539 — 6Rev. 1-00, 2011Reprint. 2016 Reprint

O 0)

CD *

CD i

p wI CD

052 wP CDro Po

2.P Q05Iroo

05

Detention pondSt°rm drainageo

MedianStorm drainage Limits of» 05 &CD & Clearing& grading

& floodplainstorm drainagefloodplain See Plates 49-6 65 6BTr & easement easement1 DetentionI pond &Istorm drainage^ | easement

50easement >Spillway designFlood limits 50

go s >Xoo> aH

Riprap outlet^ * protection/stilling basin H: Outlet

MO ^.conduit

r"o» o>o ^C/2 O

n100 Yr.

floodplainlimits5 g >n

r-<o

$ l g tocnH Storm drainageWO &I 3 floodplain >O05 easement

storm drainage CJgrading easement 12* wide (min.)gravel

CO easement >H Lockable gateLockable gates tr*access road2!O

50 50a> a>d <

05 »1 2»H*.•-« * 05>->• 2 w

05 CDb P

d ^ Limits of clearing& grading

«-** i Stormdrainage and/or

floodplaineasement

o o See Plates 49-6 65-6 ScMedian 50-6 66-6 for typical

dam sections /

o05

Itoo 05 *4o00Limits of clearing

Sc grading Detention pond Scfloodplain easement >05 RW RW Spillway design

flood limits 5dStorm drainagefloodplaineasement

H DP>TJ Xumuuumumumuuummiiiuinmumuummmmmuiuuiuui.- ^ *- ttUHwwwHwntnmninnnuuumuuuuummnuumnummwuIum*ûuuuinnuuiuuuuuuuuuuuuiuuuuuuuuuiuuunuuuiuuuuummumTrrm>ûmuuumumumumumumumuuumumumumumumumuuumumwujmiTTTttt>v^

_b uimuuumuuuuuuuumuuuuinuuuuuuuumuuumiuiuuuuuuuuuiuuuitmuuuunTTntt».y uunuiuuuuuuiiiuuuuuuiuuuiuiuuumuuiuuiiuuuuummnuniumuuiuuiuumuiuumnmTTTt^mimiiimiii i i i i i i imiiimiii i i i imimiiimmiiimimiiimiiuimmmiimiii i i i imimiiimmiimmimiummuuuuuuuuuuuuuuumimmmmmmiium«H-mmTiTTTTmTiHU.mmmmmmmmmmmmimmimiu^ iii iuiuuiimiuii i iuiumiuiiuiuiumumuiumiimiimiiuimmimmumiiumiuiiummumumiimimirmummuummuumuuumuuiHtti iuuuuummumuumumummmuumuuummumuuummuuumtm4juii iniiuii iuiuuuuummmmimimiuimummuuummnmuuum^muuumummmmimum

uuuiutTwijiuuuuiiuuij i inummiumiimummiiuumuiummimuiimmmuuuunuuummumuiuimu — luuuuiuummiuumuuumuuuumuuummuuu'HAiuumuiuuuuummumu iiiuii iuiuuuuiuuiuuii iuiuiuiiuiuuuuuiuiuuiuiimuuuuuuuuuuuuuuuuuuumuuuuuuuuuuuuuuuuuuuuuuuuuuummmummummummummumummummummummummumummuiiii i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i i irvii i i i i i i i i i i i i immU U U U” ’

H , w nl|ss|S3ag (-JO X& C/3 ^

r100 Yrfloodplain

limitsooh di

i mummummumm— ; — I Riser ill Trickle ditch1L I H5d mum u nn>nnn>nmnnn>nunnm>nnn>nunntnuuuuuinuuuuuuuuuuuumummummumumuuuumunumuuuumuuuuuuuu uuuuuuuimuiuuuumtuuiuumurcu

iU U U l l l U l U U l l l l l U U l l l l U l l U l l l U U UmummumummumumummuumuuiuuuiiiiuuuuimuuunuumTTTffluuiuummSr^^— uuuuuuuuuuuuuuumrrm+mtnTuuuuuuuuuuumTTmummum

Existing stream channeli mu dO m m i i i i m u m ul l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l i m m l l l l l l l l l l i m muuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu uuuuuuuui

„ , , , l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l i m m U U U U U U U U Iuuuu Extended draw uuuuuui,""» ni,,,,i"m,,,,” umuuumuuuuuuuuuuiuumuuuumiilium uian uuuuuui uuumuuuuuuuuuuuiimmumuuumiuuuu Hnwn device uuuuuui muuumuumumumuiiiiuumuuuuiiitU U U U VXUTT1X UCV1LC U U U U U U I llllllllllllllllllllllllllllllimillllllllimmiHlmiiiiiuiuiiiiuiiiiiiiiuiiuiiiii!iumiiiimm riXtended uuuuuuuuuuuuuuij«uuuuuuuuHiuillllllllllllllllllllllllllllllllllllllllllllllimuiu Awn-nr A lllllllllllllllllllllllliumilllllllliuiiuniuûuuuuuuuui araw aown luuuuuuuuuuuiiinuuuuuuuimul/rmu. uuuuuuuuui , muuummimmuimmimmiunmiKmm Apnecm rnad uuuuuuuuui ( BMP ) DOOl >ULmmmmmummmmmymuiir

12111111 ftV/l,cao xucxvx uuuuuuuuui v ' * uTmiuiiiiiiiimiiiiiiiiiuiuimiuiKP1111114. rirnw Hnw-n^^^^^^^'^îiimniiiiimniiiiim^^'^HDUlllllllllllllllUmilUîiiiuLU uu TVXXUU mmmilmimilmilmilmilmilmilmiuTonmmilmiUaiiiu^mm uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuiip^_device uuuuuuuuuuuuuuuuuuuuuuuuuimiuuuuuuilmirmm uuuuuuuuuuuuuuuuuuuuuuuumiiuuuuuiimiii*/mill rrrr>^. llllllllllllllllllllllllllllllllllllllllllllimuillimmi/uuuuuuuuuuuuuuumHummmmmmmmmiuiiummmtrummmiLiri

uuuiuuuiuiuiuimiu.uuuum«muuuuimuH-rmiiuuuuuuuuuuuimuu>uuminimiiiiiiiiiimmuuuiu'HuiuumiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiHiumimmmiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiumiu11mHUmmmmrmimmiumvu^xjiiiiiiuiiiiiiniuiiufmmiTTTiu>

Ripprap outletprotection/

stilling basin

ii

^°o „“ jog *O O H

H t)

d^Tl I IOutlet i

'conduit[|i

COl

I Imill o! I

Ili l di >\ K , urn oi

mu\ puli tr*ft Spillway designFlood limits

i

\ H/ 1s'

\50 DP inDetention pond Scfloodplain easementLimits of clearing

Sc gradingSee Plate 35-6 M— 6

Typ. Sect. DP$ ssStorm ^drainage Scfloodplaineasement

/ /£ >/ //H //M Limits of clearingSc grading

/ di 12* wide (min.)gravel access road

/2 / >/O /05 /fijfr tr1U U U U Uu u u u uu u u u ul l l l i u m.u u u u u

Possible conservationeasement zone

Lockable gates

*****U1H

O


Stone Weight, #o o o o o g g g §

° S § 2 10 °o oO OO O^ in

0 0 0-O ^ CO -Ho o^ IO CM COCM

26

24<DP<<D

OH HH

22 z1/

co 720

18 /coC/D CO

PH O16

r\

CO-p COcd14" FHo u

O0) /

> 12

-P" FH

10W For stone weighing165 #/ ft3

8

6

This nomograph is taken from FHAHydraulic Engineering Circular No. 14. Itprovides a reference for determining thestone size to be used at the outlet end ofculverts. The stone would be placed inaccordance with Plate 43-6 59— 6. Theriprap sizes (Class I, II , etc. ) are VDOT Std.

4

2

040 2 31

Equivalent Spherical Dia. of Stone, ft.Ref. Sec. 6-1604.7A(2),6-1604.7A(3),6—1604.7A(4) RIPRAP SIZE FOR

USE DOWNSTREAM OFENERGY DISSIPATORS

PLATE NO. STD. NO.

5B42-6Rev. 1-00. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALBoPlan oo°O

oA A%

B

Sect. A-AL*

L* — Length of riprap tobe at least 4D &may be longer inaccordance with Sect.6-1604.7 D

tA

/meL 2D50 mm-

Sect. B-B

/1 hCoyFilter clothbedding meetingVDOT spec.

This is a modified VDOT Std. EC-1. The dimensions shown are themodifications to the Std. All other parameters remain as shownon the Std. VDOT EC-1 Dwg.

Ref. Sec. 6-1604.7A(3),6-1604.7A(4), Plate 42-656-6

PLATE NO. STD. NO.RIPRAP PLACEMENT FOR OUTLETPROTECTION BELOW CULVERTS 5043-6

Rev. 1-00. 2018 Reprint

» wCD CD Note A - If exit velocity of basin is specified, extend basin as required

to obtain sufficient cross sectional area at Sect. A-A such that< natural-

channeluiCDI Note Bo Q ko deso Specified exit velocity05

VI Cross section area at Sect. A-Azo 7o /05 ao00 Note B - Warp basin to conform to natural stream channel. Top ofrip-rap in floor of basin should be at the same elevationor lower than natural channel bottom at Sect. A-A

>wCD >'0 Sect. A-A aa a

>P'SDissipator pool10 hs or 3 WQ min.

Top of bermTop of riprap

— Apron5 hs orWQ min.Note A

\ X7 X+

o AE- d O

/1* freeboardmin.

ov Berm as requiredto support riprap

Excavate to this lineBackfill with riprap

o\vNote 27 c|\V / / / / / /7/ , 22 d 50 or1.5 d max.a lita. Existing

Riprap7\ Ht<? Hori- VzA

< is zontal^K^ ra e v *a Sect. B-BL a> J aa 2 d 50 or -1.5 d max.

2 d 50 orN1.5 d max.2 d 50 or

1.5 d max. a\*} cn X7K Ptd t-1J^ £> o

Thickened or sloping-Toe optional- constructif downstream channeldegradation is anticipated

i_

x_> £ Sect. ncn <Da •• Berm as required

to support riprapM ax7Zo >I

QL 2 d 50 or

1.5 d max.B tT*NOTE B Excavate to this lineBackfill with riprapX

o i Hi' NOTE:W0 = Diameter for

pipe culvertBarrel widthfor box culvert

W0 = Span of pipearch culvert

ar?CO Sect. C-C i nt?ApproximateyZ edge of water)\$ w0% v/

£ Fv“ % r-/ rApron >\H Vii4 M |-Vo/2 ..-i-" /x 2:1a i 3 aI .

Z Symm about.izHorizontal >05 o Culverth- Berm as required

to support riprapmH 2 d 50 or "

1.5 d max.a Half PlanZo Figure XI-1 Details of Riprapped Culvert Energy Basin Sect. D-D

FAIRFAX COUNTY PUBLIC FACILITIES MANUALExtend mesh from the topof the headwall to top ofrack

Apron General Notes:• 6” - 21a compacted to a minimum 95%

of standard proctor (ASTM-618) withfilter fabric to be placed under theapron.

• Extend apron to wing-walls, in caseswhere wing-walls are part of the design.

• Apron to be tied in to the riser/headwalland wing-walls with rebar.

• Concrete to be Class A-4.• All reinforcing steel to meet the current

requirements of ASTM Spec. A-615.

eadwall Grate removed for clarity.(See details on Plate45A-6 61A-6)

coo12" OC #6 Rebareach way1*6”

05

fr-e"6" thick concrete-apron extending

entire width of thestructure

Concrete apron(see notes)— r-e” —« 5* (min) »

Trash Rack on Headwall*— 4” " Min steel rod

Plate bolted to rise

plate ^ Imin Y& ” clearance around steel rod

4”Pipe welded to vf % " Mounting hole for ^ ” bolt

Mn 12”Pipe welded to trash rackmin VQ ” clearance around steel rod

4"

SIDE PIN DETAIL

plate bolted to riser

Mounting hole for % ” bolt

% ” Min steel rod

Pipe welded to trash rackmin % ” clearance around steel rodPipe welded to plate

min % ” clearance aroundsteel rod

3"

TOP HINGE DETAILRef. Sec. 6-1604.8B,6— 1604.8C. 6— 1604.12A LOW FLOW/BMP DRAWDOWN

DEVICE(MOUNTING DETAILS)

PLATE NO. STD. NO.

3T45B-6Rev. 10-16. 2018Reprint


Pipe cover

ao

UNwwFloorstand

Operating ste: o

3S

Stem couplingS=J

V** :* v

Stem guide /4 <

4<r" A.

Anchor boltNUui oo

\ / 4

Xpa

*1a- 4-4Gate guide * 4.:O O 4

Top wedge Tnt -a 4 *4

•x 0 4 .-* - 4

Wall thimble4

Side wedge

Thrust nut Frameo-5* OpeningDisc

Bottom wedge Invertc— ^P

~H C3T ITT

Source: Rodney Hunt Company

Ref. Sec. 6-1604.10CSTD. NO.PLATE NO.EXAMPLE LOW LEVEL DRAIN

FOR A WET PONDSLUICE GATE NOMENCLATURE 6£46-6

Rev. 1-00. 2018 Reprint


Typ. Sect.Final grade2” - 4”

18” min.— i I —

CompactedSoil( 95% )

1 6” mm.'r'rN n»2 max.3” drain pipe(s)

( both sides )at a min. spacing of20 feet

3Class A3 Cone.V

10 1/2”10 1/2” 21” min.B+75min. min.

W = Design width of cone, ditchshould be based on the ManningFormula to pass flows at least= to the full capacity ofthe low flow orifice.

B = Design base width of cone,

ditch should be a min. of18”

D = Design depth of cone, ditchshould be a min. of 6” .

Bottom width of cone, ditchshould be a min. size of 21”

B+3

Notes:1. Appropriate transition section, with a min. length equal to 3x W,

shall must be provided at the ends of the trickle ditch.2. Curtain walls shall must be provided at inlet areas where water

flow is constant, & where the ditch transitions to the naturalchannel.

3. Porous stone sub-base should be avoided.4. Min. ditch bottom grade is 0.5%.

Ref . Sec. 6-1604.11C,Plate 61 6 STD. NO.PLATE NO.

TRICKLE DITCH DETAIL 6347-6Rev. 1-00. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALReservoirClassifi-cation

GeotechEngrStudy

FoundationDesignTreatment

InteriorDrainageFeatures

SeepageControlAlongConduits

EmbankmentDesign

ConstructionObservationSc Testing

See note 1 Site specificdownstream drainageblanket surroundingprincipal spillwaypipe is required

Site specific1A Required Stability Scseepage analysis Engineer

practicinggeotechnicalengineering

Licensed Prof.required

1See note 1 Site specific1B Required Site specific

downstream drainageblanket surroundingprincipal spillwaypipe is required

Stability Scseepage analysis Engineermay be required practicing

geotechnicalengineering

Licensed Prof.

See note 1Site specificdownstream drainageblanket surroundingprincipal spillwaypipe may berequired

Site specific1C Required Stability Scseepage analysis Engineermay be required practicing

geotechnicalengineering

Licensed Prof.

See note 1 2See note See note ^ Stability Scseepage analysis with permitteesnot required

In conformanceD May berequired

quality controlprogramFootnotes:

1. The guideline requirements shall must be applied as required by site conditions.2. Principal spillway pipe shall must have concrete cradle as described in the guidelines extending

from the riser for a length equal to two-thirds the total length of pipe under the footprint of thedam. The downstream one-third of the pipe shall must be bedded in accordance with Section6-1607.1B(2). The Director may allow an exception to this requirement based on site specificconditions or design.

3. Director may require a geotechnical engineering study for class D reservoirs if problem soils orother circumstances dictate a need.

Reservoir Classification Chart35

c B A

Height(ft) 15

C C B6

D D C

Dry Extended Dry

Reservoir TypeWet

Ref. Sec. 6-1603.IB,6—1605.1B, 6—1605.2A,6—1605.4A(3), 6-1605.5A(1),6-1605.5B(1), 6-1605.6C(2),6-1605.6C(3), 6-1607.1,6—1607.1B(2),6—1607.2A

STD. NO .PLATE NO.MINIMUM GEOTECHNICALDESIGN STANDARDS FOR

SMALL DAMS 6448-6Rev. 1-00, 2011 Reprint*2018 Reprint


Reservoirs Without Permanent Pool

Soil or rockSoil or rockCutoff trench may be requiredA. Homogeneous Dam

Reservoirs With Permanent Pool

Drainage blanketor toe drain

tmmm-Soil or rock

B. Modified Homogeneous Dam on Impervious Foundation

VFilter (may or

may not be required)is:

zzzzzzzzzzz

Soil or rock

C. Zoned Dam on Impervious Foundation

V Drainage blanketor toe drain

Cutoff trench^T^0*0+0+0+0+m*0+0+0+**0+0*0*0+0+0+0+0+0+0+0+0*0+0*0*0+0+0+0+0+0+0+0+0*0+0*0+0+0+0+0+ , M :g: :g:

Impervioussoil or rock Pervious stratum

D. Modified Homogeneous Dam on Shallow Pervious Foundation

4) Zone 1: Impervious soil2) Zone 2: Filter— drain material3j Zone 3: Pervious soil or rock

Note: See discussion in Sect. 6-1605.5 for design of conduits thru dam embankments

Ref. Sec. 6-1605.1C,Plates 33-6. 34-6. 40-6.41-6. 50-6 49 6, 50 6,56 6, 57 6, 66 6

PLATE NO. STD. NO.TYPICAL EMBANKMENT DAM SECTIONS(SEE CONTINUATION ON PLATE 50-6 66-6)

£549-6Rev. 1-00, 2011 Reprint*2018 Reprint


Reservoirs With Permanent PoolV

Impervious blanket ( 1 Drainage blanketand/or toe drain/

KXXXXXXXjX^uuuunnnnuiunnnuiuuunnnnnuninnnnnuninnnniuuunnnuiuunnnnunuinnnnunuinnnnuiuunnnnuiunnnniuuunnnnniuunnnuiiiiiiniuiniiuiiiiinniiiiuiuiiiuiiiiiiiiiinmiiiimiiiimimimmiiiiiiimiimiiiiiiiummimiiiiiiimmuiiiiiiiiimmiiuimiiimiimmimmumiiiimmunmunnnuinnnnunuinnnmuuunnumuuuunununuinnnnuiunnnnnunmunuuunmunniuuunnnnnuinnnmuuuununuiuuunnuiiiiiiniuiniiuiiiiinniiiiuiuiiiuiiiiiiiiiinmiiiimiiiimimimmiiiiiiimiimiiiiiiiummimiiiiiiimmuiiiiiiiiimmiiuimiiimiimmimmumiiiimmunmunnnuinnnnunuinnnmuuunnumuuuunununuinnnnuiunnnnnunmunuuunmunnnuiunnnniuunnnmuuuunnmuuuunn

Impervioussoil or rock

E. Modified Homogeneous Dam on Deep Pervious FoundationPervious stratum

Filter (may or (may not be required)

Cutoff trenchvm i n i m m i m i n i m m m m m imuuuinnmuuunnnnuuiuununuumnnunuuuinnnmuuuvmuiuunnnnuiunnnmuuunnnmuuunnumuuunnnnuuum

Mniiuiiuiiuiiuiiuiiuiuiiuiuiiuiiuiiuiiuiuiiuiuiiiuiiiiiiiiiuiiiiimuuuunuuuiuuunuuuiuuunuiununuuuiuuuuuuuumuuinuinnnnuiuununmuuunnnnuiunnnnumunnnmuuunnm

Impervioussoil or rock Pervious stratum

F. Zoned Dam on Shallow Pervious Foundation

VFilter (may or ( 2Jmay not be required)

Impervious blanket ( 1

uiuuuuuumuuuuumuuuuuumuuuuuumuuuuuuiuuuuuiuuuuuuuiuuuuuuuiuuuuuuuumuuuuuiuuuuuuumuuuuuuiuuuuuuuuuuumuuuuumuuuuuumuuuuuumuuuuuumuuuuuumuuuuumuuuuuumuuuuuumuuuuuumuuuuumuuuuuumuuuuuumunnuuuinnnnuuinnnnuuuinnnnuuuinnnnuuuinnnnuuuinnnnuuinnnnuuuinnnnuuuinnnnuuuinnnnnuinnnnuuuinnnnuuuinnnniuuunnnniuunnnnniuunnnnniuunnnnniuunnnnniuunnnuniunnnniuuunnnniuuunnnniuuunnnnuninnnnniuunnnnniuunnnnuiuunnnnuiunnnnuuiunnnnuuiunnnnuuiunnnnuuiunnnnuuinnnnuuuinnnnuiuunnnnuiuunnnnniunnnniuuunnnnuuiunnn

n i n n i n n n i n t n n n n n n i n n n i n i n n i n n n i n n n H n n n n n n n i n n n i n i n t n n n n n n i n n n n n n n n t n n i n n n i n m n n n n i n n m n n n n n n n n m n n H n i i n n n n immm Impervioussoil or rock

G. Zoned Dam on Deep Pervious Stratum

Pervious stratum

Filter (may or ( 2Jmay not be required)V

Impervioussoil or rock

H. Alternative Zoned Dam

(T) Zone 1: Impervious soilZone 2: Filter-drain materialZone 3: Pervious soil or rock

Note: See discussion in Sect. 6 — 1605.5 for design of conduits thru damembankments

23

Ref. Sec. 6-1605.1C,Plates 33-6. 34-6.40-6. 41-6. 49-6i-556 6, 57 6, 65 6

STD. NO.PLATE NO.TYPICAL EMBANKMENT DAM SECTIONS(CONTINUED FROM PLATE 49-6 6&50-6Rev. 1-00, 2011 Reprint*

2018 Reprint


LegendMax. Core

Min. Core B, for dams on deep perviousfoundations without positive cutoff trench

Min. Core A, for dams on imperviousfoundations or shallow pervious foundationswith positive cutoff trench

<L of dam1I- 10’ -

V

PerviousPervious

'' A z y' ^ / »

^ Lz

StrippingOriginal ground surface

Size range of impervious cores used in zoned embankments, 288-D-2497.

Note: X and Y are the horizontal components of the upstream and downstreamembankment slopes, respectively.

Reference: ’’Design of Small Dams” , Bureau of Reclamation, 3rd Edition, 1987.Ref. Sec. 6-1605.6B( l )

STD. NO.PLATE NO.SUGGESTED MINIMUM & MAXIMUMCORE SIZES FOR SMALL DAMS

WITH ZONED EMBANKMENTS 6H52-6Rev. 1-00. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALRecommended Slopes for Small Homogeneous

Earthfill Dams on Stable FoundationsSubject to

RapidDrawdown1

Upstream DownstreamSlope

SoilClassification2 SlopePurposeCase Type

GW,GP,SW,SP Pervious unsuitableDetentionHomogeneous or

modifiedhomogeneous

A GC,GM,SC,SMCL,MLCH,MH

or 2.5:1 2:1NoStorage 3:1 2.5:1

2.5:13.5:1

GW,GP,SW,SP Pervious unsuitable

GC,GM,SC,SMCL,MLCH,MH

3:1 2:1YesStorageB Modifiedhomogeneous

3.5:1 2.5:12.5:14:1

Drawdown rates of 6”levels.earthfill dams.

or more per day after prolonged storage at high reservoirOL and OH soils are not recommended for major portions of homogeneous

Pt soils are unsuitable.Recommended Slopes for Small ZonedEarthfill Dams on Stable Foundations

Subject toRapid

Drawdown2Core Material g Upstream DownstreamClassification

Shell MaterialClassification SlopePurpose SlopeType

GC,GM,SC,SMCL,MLCH.MH

4 Rockfill,GW,GP,Not Critical SW (Gravelly),

or SP (Gravelly)

Zoned withMin.

Core A1

2:1 2:1Any

ZonedwithMax.Core1

2:1 2:1GC.GMSC.SMCL,MLCH.MH

DetentionRockfill,GW,GP,SW, (Gravelly),

or SP (Gravelly)

2.25:12.5:1

2.25:12.5:1

or NoStorage3:1 3:1

2.5:12.5:1

2:1GC.GMSC.SMCL,MLCH.MH

Zoned withMax.Core1

Rockfill,GW,GP,SW, (Gravelly),

or SP (Gravelly)

2.25:12.5:1Storage Yes 3:1

3.5:1 3:1

xMin. & max. size cores are shown on Plate 52-6 Figure 6-43.2Rapid drawdown is 6” or more per day after prolonged storage at high reservoir.30L and OH soils are not recommended for major portions of the cores of earthfill dams,

levels. Pt soils are unsuitable.4Rapid drawdown will not effect the upstream slope of a zoned embankment that has alarge upstream pervious shell.

Note: Slopes steeper than 2:5:1 shall will not be permitted without Directorapproval.Reference: ’’Design of Small Dams” , Bureau of Reclamations, 3rd Edition, 1987.

Ref. Sec. 6-1605.6C( l )RECOMMENDED SIDE SLOPES

FOR SMALL DAMS ONSTABLE FOUNDATIONS

STD. NO .PLATE NO.

6D53-6Rev. 1-00. 2018 Reprint


Typical Access Road Section

20’ (min.)easement width

12’pavement width— 2% 2%— 47

6” VDOT Std. 21A, prime &double seal surface treatment inaccordance with VDOT Std.is recommended.

Subbase shall must be adequateto support H20 wheel loading.

Note: Where maintenance accessis located between or nearresidential lots, approvedgeoblock pavement alternativeshould be considered.

Ref . Sec. 6-1606.2GSTD. NO.PLATE NO.STANDARD MAINTENANCE ACCESS

ROAD DETAILS FOR STORMWATERMANAGEMENT PONDS ¥054— 6Rev. 1-00, 11-05. 2018

Reprint

wP M»r** *<CD

U1CJI 2CJ1 °I 03

I Note: W6 x 12, A36all exposed surfaces, lock assembly, gate hinges, &stopper, shall must not be painted as per VDOT Spec. Sect. 239.04.

Oo03 |too 1 03S‘§3CD

>50(D'0•1 50M-8.

>X

Access Road ninO ^O ®

« n

OSee Detail ” B” *for gate assembly c|5,<L <L 2See Detail ” A” *

for lock assembly H3” ~i9* — 9” 3” -

r 9*-9”/•3” dia. galv. pipe / T)\

c|W6 X 123” dia. galv. pipeW6 X 121-2” to\ 4’ — 0” r1m 2” dia. galv. pipeExisting earth ol'-6”4* T

7„3’-0” V7 ^:!!i7

Existing earth >2” dia. pipe embedded in2*-6” cone, as shown to act as gate

stopper; the pipe shaft mustbe filled with cone.

7W 2’ — 0” , o• < : < X% 13*-6 \ tT*Q C/3 I k/«« :*• * * •• « \C/3 H• *

|- 9”1? •

in

$ 24”Class ” B” Cone.£ >cn H

WcnI 3o >View of Gate at Entrance05

tT*

coHO

* See 55A-6 ?±Ao


Two 3” x 1-4” flat irons of 10” lengtheach welded to 3” dia. galv. pipes 8c 1/4” thickthick Cap at the end of 3” dia. galv. pipes

3” dia. galv. pipeTop View3” dia. galv. pipe

i” £ <L3” XI” Slot -NJ— Cap 1/4” flat iron plate3” dia. galv. pipe3” dia. galv. pipe C — 3” dia. galv.

P Hi pipe

c / A. 11 / ..1 3

I=Z3Z^ Flatten end of 2”dia.

}galv. pipe, weld

to 3” dia. galv. pipe9” ^a,

;r*e

2” dia.9”Flatten 9” lengthof 2” dia. galv. pipe at theends as shown 8c weld to 3”dia. galv. pipe

DetailSection C-C

galv. Pipe

Detail ” A” *Lock Assembly

Top View r 3/8”r 3/8”W6 x 12 Q”Fi6” x 6 ” x 3/8”

angle of 6 ”length welded to W6 x 12

3” dia. galv.*- pipe

s — %s~ Welded joint

W 6 X 12

3” dia. galv. pipe II3” dia. galv. pipe2’— 7 7/8” long- l~ *r11[L dia. galv. pipe

CVJ

6” x 6” x 3/8” >

angle weldedto W6 x 12 as shown

Welded joint Welded joint"2” dia. galv.

pipe2” dia. pipe welded to

|3” angle. Length = 3”mIT '

i L o”6” ^3/8” *3dII• vv v a •*• •• • V •

Class ” B” cone.Class ” B”cone. Detail ” B” *

Gate AssemblyRef. Sec. 6-1606.2G,Plate 55-6 7L-8 STANDARD ACCESS

ROAD GATE DESIGN* See Plate 55-6 6.

STD. NO.PLATE NO.

YL55A-6Rev. 1-00. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALB

Standard MH-1/

/.

R D[s~T|R

~M]p

[ )ii 17

\/CO

II\ *»

A / co\ A CM I/VMt CO/ V \

/\\\\\

/\

B1’ — 8 -

MINIMUM HEIGHTS2’— 0 ”

12” 15” 18” 24”PIPE2’-2” H’ 3.62 4.163.08 3.352’-8”

PLAN VIEW

m.'y.m ivV -

r.• 5*CM

i. ' .9 LI

• .•* * A- :

i2' :Pi V:/• s i .• • - t -- •. *!• * 4

•'4 «•4 *:• 4';4o 4

44 45., 4 . *•

*.-P .>.. - 4*4' •• J • 4•P

•:\±i „ .vCdV 624”* / *«.

03 tP .«48”o> vv'•f • . V' f •03 4.. -4.« Wi ID.* . *

SECTION B-Bv- •..*d Ao 4.. X *4‘.

• 4'

• -4

^

*o H-03 ft4-• ••CO .*••:-V 4'*4.03 •* •4

03 03Cti 034'

*. "PHCQ 4 PA ••• 'A > 4

cd>*

SECTION A-A NOTE:Manhole to meet current requirementsof ASTM specification C-478

Rev. Sec. 6-1103.46 1104.4 STD. NO .PLATE NO.

MODIFIED YARD INLET(SINGLE THROAT) YI-2rHQ

fTJ56-6Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint


B

Standard MH-1A A/

X\

\ l\\. \D\ V i \

/ ,/ co

I\ W » D 9 / •*

coI I v c\2/\ I7\ n coxJ V

/ \\

B— r-8” —2* — 0”

2* — 2”2*-8 ”

PLAN VIEW

#4 typ. 4 sides

s nmCO 4

*JJ gj 4

in* I

<J* i; i

'1.v»- :- *!

4.l *4*

4* .. .*4

f•4V

3 ea. #4 typ. bothsides & back /2”' #4 - 6” 0C

242” #4 - 6” OC

SECTION B-BSECTION A-A

Ref. Sec. 6-1103.46 1104.4 TOP DETAIL

MODIFIED YARD INLET(SINGLE THROAT)

STD. NO .PLATE NO.

Y357-6 YI-2Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint


B

\\Standard MH-1 \/ \

\

^ / A\/ NA N \/

,Jco s

\/ At / , \' tl [jl D\ ^ \irr£[g ?Llg\ '\ \p qi

I I 11/ II co

// I\ CMV / /\ CO\ /\//\ / \ /\

//

B

-— 2’ — 0" MINIMUM HEIGHTSPIPE 12” 15” 18” 24”

2’ — 2 -H’ 4.163.353.08 3.622’-8 -

PLAN VIEW

w. „CM 1'44.*I I»-- y- ;-•r i •*>•:;P 4- : -<

*4. ‘••V* * . v-

O : i . -4‘:• «•4 i >•;M *. 4»•: 4 '* •*3.cd ..; .•i Vrv V6 ” 24”

* .

.. “ *t'

03SH f

48” * /•••>03

03 •- -4•rH ... ..; ffiSi v*4

ID:• .

SECTION B-Ba K MOA.- ** > * A

*

' AC3 *+0v -73 .‘•- -••V ^03 •A

03 NOTE: Manhole to meet currentrequirements of ASTMspecifications C-478

03Cti 0)03 u

cti>

SECTION A-ARef. Sec. 6-1103.46 1104.4 STD. NO .PLATE NO.

MODIFIED YARD INLET( DOUBLE THROAT) 7458-6 YI-3

Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint


B

•j

oI

Standard MH-1 \ /\ /

A\A vA S

* .I co

\

/ j[ fu £ !

flnESSHOSV\p C 1 / // /\ \\ X1 [ ] ry // /

\\i c o

IT I\ CM\ /) \/ \

oI

B

^ l ’-8^2* — 0” —2* — 2”2’-8 ”

PLAN VIEW

3 ea. #4 typ.both sides #4 typ. 4 sides •»

coV ;w-•«

CO v \isaai.44s 4

*»J*

* lOCMi. I*4 ‘I -’ .JJ * > : :v

«• : •J T *•« . . .. - . *.* •

• 4 «

lO ;•4. •K > «•4 « ..A

- 24”#4 -6” 0C

extend up into the sides

#4 - 6” OC2” 2”

SECTION A-A SECTION B-B

Ref. Sec. 6-1103.46 1104.4 TOP DETAIL

MODIFIED YARD INLET(DOUBLE THROAT)

STD. NO.PLATE NO.

YI-3Y59-6Rev. 1-00, 11-05, 2011Reprint. 2018 Reprint

FAIRFAX COUNTY PUBLIC FACILITIES MANUALWording for bioretention facilityand vegetated swales with checkdams (swales designed tocapture and treat the waterquality volumes)

Wording for vegetatedswales (grass)without check dams10”

r 1 r 1BIORETENTION FACILITYWATER QUALITY

MANAGEMENT AREAWATER MAY POND AFTER STORM

THIS AREA HAS BEENREFORESTED AS A LOWIMPACT DEVELOPMENT

PRACTICE.GRASS SWALE

WATER QUALITYMANAGEMENT AREA

8”MAINTAIN GRASS AT4-8 INCH HEIGHT

THIS AREA IS NOT TO BEDISTURBED EXCEPT FORREQUIRED MAINTENANCE

NO DISTURBANCE ORCUTTING OF VEGETATION

IS ALLOWED. L J L J

Wording forreforestation sign48” TO 72”

r===r-i • • •i i 1 1 1-• i i

36”

GENERAL REQUIREMENTS

The sign is to be placed on a 3” ” U” channel post 8’ long.The sign is to be placed at approximately 150 foot intervals alongthe perimeter of the reforested area or the bioretention facility.The sign is to be placed at approximately 150 foot intervals alongthe length of vegetated swales on alternating sides. Each reforestedarea, bioretention facility, and vegetated swale shall must have aminimum of one sign.The sign shall must be made with reflective materials and be greenwith white border and standard 1/2” lettering.Alternate design may be approved by the Director.Sign is not to be placed in existing or proposed VDOT right-of-way.Signs for bioretention facilities on individual single family lots maybe placed on wood or metal posts at heights as low as 30” aboveground and be made of non-reflective materials in colors other thangreen and white.

1 )2)

3)

4)5)6)

Ref. Sec. 6-1307.3C,6— 1308.3C. 6— 1303.3D.6— 1304.3B. 6— 1310.3C.6— 1312.3D. 6— 1315.3C.6— 1316.3C. 6— 1317.3C.6— 1318.3C. 6— 1319.3CRev. 3-07, 2011 Reprint*2018 Reprint

PLATE NO. STD. NO.REFORESTED AREA, BIORETENTION,

OR VEGETATED SWALE SIGN BF60-6


Filter fabricsee Section6-0902.2NO— Trench width (see note 3) —Ground surface

SUl\J/ — \J/

Final backfill j.shall must " zjmeet VDOT }:

standards

Pipe embedment

Place and workembedment material byhand to ensure all }:excavated voids and Ehaunch areas are filled. IThoroughly compactunder pipe haunches to =ensure complete contact ]=[j]with pipe bottom and to EjJjE=fill voids below pipe.

Initialbackfill overpipe inaccordancewith6-0902.2NO(3)

Spring line/

Haunch Area

4” min bedding(see note 1)

NOTES

1. Bedding shall must be in accordance with VDOT standards unless specifiedon the plan.

2. Backfill material shall must be placed alongside the pipe in uniform layersin lifts not to exceed 6” in depth. Backfill material shall must be VDOTaggregate No. 25 or 26, aggregate base material size 21A or 21B, orflowable fill. Compaction shall must meet VDOT standards and be inaccordance with PFM Section 4— 0503 for minimum required site densitytesting.

3. Trench width shall must be specified by the Engineer and meet VDOTstandards. Refer to ASTM D2321 for procedures for trench excavations thatare especially important in flexible thermoplastic pipe installations such assupport of trench walls and trench boxes. Moveable trench boxes shall maybe used below the pipe embedment per ASTM D2321.

Ref. Sec. 6-0902.2N(3l6 0900.20(3) STD. NO.PLATE NO.

HDPE PIPE TRENCH9361-6Rev. 1-03, 2011 Reprint*2018 Reprint

FAIRFAX MANUAL...FAIRFAX COUNTY PUBLIC FACILITIES MANUAL H (Ft. 500 Tc minutes 400 200 EXAMPLE...

Documents

Transcript of FAIRFAX MANUAL...FAIRFAX COUNTY PUBLIC FACILITIES MANUAL H (Ft. 500 Tc minutes 400 200 EXAMPLE...