HomeMy WebLinkAboutDrainage Reports - 04/01/2015City of Ft. Collins Ap ve Plans
'✓`.. �'` Approved B
Date
C 0Lss0N
ASSOCIAYLS
June 12, 2014
Glen Schlueter
Stormwater Engineering
City of Fort Collins
281 North College Avenue
Fort Collins, CO 80524
RE: Drainage and Erosion Control Letter
Rigden Farm Filing Six, Tract Z — Multifamily
Dear Mr. Schlueter:
Olsson has completed an analysis of the drainage design to determine the changes from the
proposed to the original design of Tract Z of the Rigden Farm — Filing Six project based on the
Final Drainage and Erosion Control Report for Rigden Farm — Filing Six, prepared by JR
Engineering, dated December 13, 2000, revised February 8, 2002.
The original basins' imperviousness was compared to the imperviousness of the proposed to
determine if further analysis would be required. The original design used a percent
imperviousness of 70 percent for the multifamily areas including Tract Z. The percent
imperviousness of the proposed site is calculated to be 55.2 percent. Based on the calculations,
a reduction of the developed runoff would be anticipated. See attached calculations and
supporting material. Since the intended drainage patterns will remain the same, detailed
analysis of the changes will not be required.
If you have any questions or need additional information, please contact me.
Sincerely,
Olsson Assoc
Daniel Hull, PE
Senior Project
Enclosures
5285 McWhinney Blvd., Suite 160 TEL 970.461.7733
Loveland, CO 80538 www.olssonassociates.com
Project: Tract 2 Multi -Family
Project Number: 13-2449
Proposed Design
Basin
Area (SF)
AREA(AC)
Landscape
Paved
Roof
Percent
Impervious
Al
42,151
0.97
9,583
19,166
14,810
77%
A2
20,828
0.48
1,861
11,160
7,807
87%
A3
32,705
0.75
22,938
1,763
8,004
27%
A4
17,156
0.39
10,122
464
6,570
37%
A5
15,831
0.36
9,979
1,116
4,736
34%
Total 1 128,6711 2.95 1 54,483 1 33,669 1 41,927 1 55.5%
6/12/2014
Olsson Associates
Copyright 2014
A Engineering
2620 E Prospect Rd.. Ste, 190
Fort Collins, CO e525
RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION: Rigden 11
PROJECT NO: 9164 12 and 9164.15
COMPUTATIONS BY: B. Strand
DATE P- //
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt):
Sidewalks (concrete):
Lawns (fiat c2%. sandy soil):
General multi -farm r area:
General single-faml)y area:
General commercical area:
Runoff
%
coefficient
Impervious
C
0.95
100
0.95
96
0.10
0
0 65
70
0.65
55
0.85
90
SUBBASIN
DESIGNATION
TOTAL
AREA
(ac l
TOTAL
AREA
(sa.!t)
SIDEWALK
AREA
(s0 h)
PAVED
AREA
(so n)
LANDSCAP
AREA
(sa r)
SINGLE-
FAMILY
(34111
COMMER.
AREA
(so.It)
RUNOFF
COEFF
(C)
%
trnp"ous
MULTI*
FAMILY
169
0.25
11.040
915
4.442
2.144
0
3.539
0
0.69
66
170
0-81
35.134
920
4.990
9.778
0
19,446
0
0.55
47
171
1 11.50
500.771
15,460
0
342,427
0
142.854
0
0.28
19
172
0.33
14.273
2.325
8,896
3.052
0
0
0
0.77
78
173
0.86
37,59E
4,000
19.609
6.710
0
7.279
0
0.74
73
174
2,49
108.350
4,750
17.209
34.368
0
52.023
0
0.54
46
175
1.55
80,533
0
0
50.233
0
30.300
0
0.31
21
176
3.76
763,947
9,400
35,857
11.840
0
4,06.750
0
0.69
63
177
0.49
2 1. 182
2250
7.313
1.954
0
9,665
0
0.73
70
178
t08
46.946
0
0
33,377
0
13.569
0
026
16
179
1.D4
45.424
0
0
13.509
0
31,914
0
0.49
39
4.80
t59
69,708
6.937
10.230
14.208
19.326
18.408
0
0.61
59
lei
1.30
56,840
3.770
13,955
4.969
34.146
0
0
0.70
73
182
165
71.843
7.525
7.325
29.782
33.203
0
0
0.46
45
183
2.75
119,524
4,890
0
103,321
11413
0
0
0.19
11
184
114
49,455
4.670
11,838
19.909
13.038
0
0
0.53
51
185
1.14
49.533
3,275
13,861
7.581
24.016
0
0
0.67
69
186
4.40
191,467
6.415
7,325
133.111
24,361
0
0
0.22
16
187
0.46
79,925
1,325
4,628
7.392
0
12.580
0
070
64
188
0.86
37,276
1,690
6.387
2.211
28,988N
0
0.88
72
189
1.35
58.945
4,145
12.618
7,324
0
0
0.67
61
190
243
705.837
6.250
20.242
7,785
71.559
0
0,68
72
191
3.10
735,034
3,705
17,067
40,641
_ 56,714 _
0
0.52
49
492
1.62
70.510
3,200
71,812
17,552
0
0
0.58
51
193
026
11,384
0
0
6,950
0
D
0.31
21
194
125
54,270
650
0
21.522
0
0
O44
34
195
O.B9
3e.923
0
17.042
0
27.8810
0.74
79
196
1.76
76.572
900
0
33.482
0
0
0 st
31
916400* +As
is unofficial copy was downloaded on Aug-15-2013 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
Page 3
CAOLSSON
A SS OCI AT E5
Glen Schlueter
Stormwater Engineering
City of Fort Collins
281 North College Avenue
Fort Collins, CO 80524
RE: Low Impact Development Letter
Rigden Farm Filing Six, Tract Z — Multifamily
Dear Mr. Schlueter:
September 24, 2014
Per the City of Fort Collins Ordinance #152: (1) No less than fifty percent (50%) of any newly added
impervious area must be treated using one or a combination of LID techniques; and (2) no less than twenty
five percent (25%) of any newly added pavement areas must be treated using permeable pavement
technology that is considered an LID technique.
Based upon the ordinance and the newly added impervious area of 75,596 square feet within Rigden Farm
Filing Six Tract Z, a total of 37,798 square feet must be treated by LID techniques. With the newly added
pavement area of 33,669 square feet, a total of 8,417 square feet of pavement area must be treated with
permeable pavement technology. This will be accomplished by the following:
A rain garden will be implemented on the northern side of the site to treat runoff from Drainage Basin
Al which includes 33,976 square feet of impervious surfaces. Additionally, permeable pavement will
be implemented on the southern side of the site to treat runoff from Drainage Basin A2, a total of
18,967 square feet of impervious surfaces. Therefore, the total area of impervious surfaces treated
by LID techniques totals 52,943 square feet, exceeding the required treatment area of 37,798.
Please see the attached calculations and supporting material.
2. Of the 18,967 square feet of impervious surfaces treated by permeable pavement within drainage
basin A2, 11,160 square feet consist of pavement. The total area of pavement treated by permeable
pavement is 11,160 square feet, exceeding the required treatment area of 8,417 square feet. The
excess treatment area was a result of the design requirements of permeable pavement. Please see
the attached calculations and supporting material.
If you have any questions or need additional information, please contact me.
Sincerely,
Olsson Associates
Daniel Hull, PE
Senior Project Engines
Enclosures
5285 McWhinney Blvd., Suite
Loveland, CO 80538
www.oissonassociates.com
IN
Project: Tract Z Multi -Family
Project Number: 13-2449
Proposed Design
Basin
Area (SF)
AREA (AC)
landscape
Paved
Roof
Percent
Impervious
Al
42,151
0.97
9,583
19,166
14,810
77%
A2
20,828
0.48
1,861
11,160
7,807
87%
A3
32,705
0.75
22,938
1,763
8,004
27%
A4
17,156
0.39
10,122
464
6,570
37%
A5
15,831
0.36
9,979
1,116
4,736
34%
Total 1 128,6711 2.95 I 54,483 1 33,669 1 41,927 1 55.5%
6/12/2014
Olsson Associates
Copyright 2014
Area -Weighting for Runoff Coefficient Calculation
Project Title:
Catchment ID:
Illustration
y. too
Instructions: For each catchment subarea, enter vaiues for A anc C
Subarea
Area
Runoff
000ii
Product
ID
acres
Coeff.
A
C*
CA
input
input
input
output
Pavement
0.43
100.00
43.00
Roof
0.36
90.00
32.40
Landsca a
0.18
0.00
0.00
Porous
40.00
0.00
Sum:
0.97
Sum:J
75.40
Area -Weighted Runoff Coefficient (sum CA/sum A) = 77.73
'See sheet "Design Info" for inperviousness-based runoff coefficient values.
132449_Runoff Calm Weighted C
1212 -, 4 3 24 PM
CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: Rigden Farm Filing Six. Tract Z MF
Catchment ID: Al
I. Catchment Hydrologic Data
Catchment ID = Al
Area = 0.97 Acres
Percent Imperviousness = 75.40 %
NRCS Sal Type = B A. 8, C, or D
11. Rainfall Information I (inch/hr) = C1 ' P1 /(C2 + Td)AC3
Design Storm Return Penod, Tr = 2 years (input return period for design storm)
C1 = 28.50 (input the value of Cl)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P 1= 0.85 inches (input one-nr precipitation —see Sheet "Design Info")
111. Analysis of Flow Time (Time of Concentration) for a Catchment
Runoff Coefficient, C = 0.51
Overide Runoff Coefficient, C = (enter an ovende C value :f desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5 = 0.54
Overide 5-yr. Runoff Coefficiert, C =
Reaclk 3
(enter an everide C-5 value if desired, or leave blank to accept calculated C-5 1
Reack 2
Illustration
f v w-erLad
Beach I now
Flaw Directiurt
catchment
BouruLry
NRCS Land
Type i
Heav;
Meadow
diage/ i
Field i
Shor
Pasture/ I
Lawns
Neany
Bare
Grcurd
gassed
Swales/
Waterwa
?aved Areas &
Shallow Paved Swalas
(Sleet Flow;
Conveyance
2 5
E5
7
10
15
20
Calculations.
Raach
tD
Overland
Slope
S
ft/ft
input
Length
L
It
Input
5-yr
Runoff
Coeff
C-5
output
NRCS
Convey-
ante
input
Flow
Velocity
V
fps
output
Flow
Time
Tf
minutes
output
0,0100
25
0.54
N/A
0.08
5.02
1
2
3
4
5
1 0.0100
Sum
359
384
20.00 2.00
Computed Tc =
Regional Tc =
User -Entered Tc =,
2.99
8.01
12.13
801
IV. Peak Runoff Prediction
Rainfall Intensity at Computed Tc, I = 2.51 inch/hr
Rainfall Intensity at Regional Tc, I = 2 13 inch/hr
Rainfall Intensity at User -Defined Tc, I = 251 inch/hr
Peak
Flowrate,
Op =
1.24
cfs
Peak
Flowrate,
Qp =
1.06
cfs
Peak
Flowrate.
Qp =
1
24
cis
132449 Runoff Caics, Tc and PeakQ 6/12/2014, 3:25 PM
Design Procedure Form: Rain Garden (RG)
Designer:
Company.
Date:
Project:
Location:
ssz
OLSSON ASSOCIATES
October 1, 2014
RIGDEN FARM TRACT Z
FORT COLLINS. CO
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area. I,
(100% if all paved and roofed areas upstream of rain garden)
8) Tributary Area's Imperviousness Ratio (i = I.110C)
C; Water Qualify Capture Volume (WQCV) for a 12-hour Drain Time
(WQCV= 0.8' (0.91a i'- 1.19' ?+ 0.78' i)
0) Contributing Watershed Area (including rain garder area)
E) Water Quality Capture Volume (WQCV) Design Voiume
Vol = (WQCV ! 12)' Area
F) For Watersheds Outside of the Denver Region, Depth of
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region,
Water Qcality Capture Volume (WQCV) Design Volume
H) User Irput of Water Quality Capture Volume (WQCV) Design Volume
(Only If a differer! WQCV Design Volume is desired)
Basin Geometry
A) WQCV Depth (12-Inch maximum'
B) Rain Garden Side Slopes (Z = 4 min., horiz disc per unit vertical)
(Use "0" i( rain garden has vertical walls)
C) Mimimum Flat Surface Area
D) Actual Flat Surface Area
E) Area at Design Depth (Top Surface Area)
i Rain Garden Total Volume
(V? ((ATm + AAe ) / 2) ' Depth)
3 Growing Media
4 Underdrain System
A) Are underdra:ns provided?
B) Underdrair system orifice diameter for 12 hour drain time
I. = 78.0
= 0.780
WQCV = 0.25 watershed inches
Area = 42.051 sq 4t
VWQcv = cu r!
de = 0.43 in
Vwocv OTHER = 886 6 cu It
Vwccv usrR 2 to It
avocv = 6 in
Z= 4.D0 h/ft
AM„ =
591
sq
ft
A °,,,,, =
1710
sq
it
AT. =
2165
sq
it
VT=
969
cu
1t
�00 18" Rain Garden Growing Media
Q Other (Explain):
Choose One
rG YES
0 NO
i) Distance
From
Lowest EievatK n of the
Storage
y= 2,0 h
Volume
to the
Center of the Orifice
li) Volume to Drain in 12 Hours
iii) Orifice Diameter. 3/8' Minimum
Vol,?= 887 cult
Dc = 0.69 ir
Shoat 1 of 2
Rain Garden.xlsm RG 10/1/2014112:07 PM
Design
Procedure
Form: Rain Garden (RG)
Sheet 2 of 2
Desigrer- SSZ
Company: OLSSON ASSOCIATES
Date: October 1, 2014
Project: RIGOEN FARM TRACT Z
Location: FORT COLLINS, CO
Choose One
S Imoermeable Geomembrane Liner and Geotextile Separator Fabric
r
QYB
A) Is an impermeable liner provided due to proximity
Q No
of structures or groundwater contamination?
Choose Cne
6. Inlet / Outlet Control
Sheet Flow- No Energy Dissipation RequiredA)
Inlet Control
r(� Concentrated Flow- Energy Dissipation Provided
Chon� One
7 Vegetation
QQ Seed (Plan for frequent weed controll
Q Plantings
Q Send Gram or Other Nigh Infiltration Soc
Choose One
9 Irrigation
G fcc NO SPRINKLER HEADS ON FLAT SURFACE
A) Will the rain garder be irrigated?
Notss: --- —
NG
Rair GardenAsm. RG 10/1/2014, 12:07 PM
Design Procedure Form: Permeable Pavement Systems (PPS)
Designer: ss2
Company: Olson Associates
Date: June 12. 2014
Project: Rlgden Farm Filing six, Tract 2 MF
Location: Fort Collins, Colorado
1 Type of Permeable Pavement Section
A) What type of section of permeable pavement is used?
(Based on the and use and activities, proximity to adjacent
structures and soil characteristics I
B) what type of wearing r-ourse7
2 Required stcrage Vuume
A; Effective Imperviousness of Area Tributary to Permeable Pavement. I,
B) Tributary Area's Imperviousness Ratio (I = 111/ 100)
C) Tributary Watershed Area
(irclading area of permeable pavement system)
D) Area of Permeable Pavement System
(Minimum recommended permeable pavement area = 6314 sq h',
E; Impervious Tributary Ratio
(Contributing irrpervwos Aroa / Permeable Pavement Ratio)
F) Water Quality Capture 'Volume (WOCV) Based on 12-hour Dram Time
(WOCV•M8'(091'ion-119'iv.0.78'i)/12)'Area)
G) Is flood control volume being added'
3. Depth of Reservoir
A) Minimum Depth of Reservoir
(Minimum recommended depth Is 6 inches)
B) Is the slope of the reservorrisubgrade interface equal io 0%7
C) Porosity (Porous Gravel Pavement < C 3, Others < 0 40)
D) Shupe o' the Base Course/Subgrade Interlace
E) Length 9etwe-en Lateral Flow Barriers (max = 18 79 C I
F) voume Provided Based on Depth of Base Course
Fiat or Stepped V = P' ((Dm..rY12)' Area
Sloped V = P ' I(Om,,,. (Don„- 6'SL-1)) / 12)' Area
4 Lateral Flow Barriers
A) Type of �Ieral Flow Barriers
B) Number of Perrteable Pavement Cells
5 Penmaler Berner
A, Is a perimeter barter p"ovldeo on all sides of the
pavement system?
(Recommeded for PICP, concrete gnd pavement or for any
no.,nfltration se0cir, )
O No InhRraeon
Q Partial Infiltration Section
Q Full infiltration Seam
Choose One.
O PIC➢
Q Concrete rid Pavement
0 Pervious Concrete
O Parma Gravel
= 870
= 0 870
A; �. = 2C.828 sq ft
Air:: = 6,967 sq fl
Rt s 1 7
WOCV = 524 cu It
Choose One
O YES
p No
Dm,,, = 6.0 inches
Goose One
Q YES- Rat or Stepped Installation
Q NO Sloped installation
P = 040
S= OV20 E/ft
L a 18.8 ff
V = 639 cu 8
Volume assumes uniform slope 6 lateral flow barer spacing.
Goose Dre
O Concrete walls
Q PVC geomembrane installed normal ;o crow
O N/A Flat instaliatlan
Q Other (Describe)
Cells = 10
Chwa One
rp YES
m NO
Sheet 1 of 2
Design Procedure Form: Permeable Pavement Systems (PPS)
Designer.
Company:
Date:
Project:
Location:
SSZ
June 12, 2014
Rlgdan Farm Filing Six, Tract Z
Fort Collins, Colorado
Pr1W,
6 Fitter Material and Urderdram System
Choose Ork
A) Is the underdram placed below a 6-inch thick layer of
COOT Class C fitter matenal7
®yam
C NO
O NIA
choose one
B) Diameter of Slotted Pipe (slat dimensions per Table PPs-2)
—
® 4inct
O 61nU
C) Distance from the Lowest Elevation of the Storage Volume
y a 0.7 it
(i.e the bottom of the base course to the certar of d.e orKce)
choose One
�o
Ly
Choose Dne
Q Placed above the Bner
O p aoad above and below the km
6 Outlet
(Assumes each call !as similar area. subgrade s:ope. and length
between lateral barriers ;unless subgrade is flat) Calculate cells
individually where leis varies )
A) Depth of WOCV in the Reservoir
Gwmv = 450 :riches
(Elevation of the Flood Control Outlet)
B) Diameter of Orifice for 12-hour Drain 'ime
Do,r,=, • 066 inches
(Use a minimum crifice diameter of 3/8-inches)
Notes,
/ i�48
18 LF OF 8' HOPE
OUTLET STRUCTURE
SEE DETAIL
I4887.6
4887.6
4886.7
INSTALL 87 LF
OF 4' SLOTTED
PIPE
3.0'
TOP OF RAIN GARDEN _
ELEV: 4887.6
BOTTOM OF RAIN GARDEN
ELEV: 4886.75
INSTALL 90' SWEEP BEND
TO SURFACE CLEAN OUT
WITH WATER TIGHT CAP.
m• I
7
\ N
Z�
¢
ou
cn O
I A N
J Q
O
4887.606
4887.60�
4887.40\�
�4887.60 \ 010` 20' 40'
. • 4886.75 - \ SCALE IN FEET
18.5' OVERFLOW PATH RAIN GARDEN NOTES
•' ELEV:4887.40
•' •' •' •' •' • 1. CLASS C FILTER MATERIAL SHALL BE GRADED AS FOLLOWS: 100%
• • . • . • . • PASSING N4•. 60-100% PASSING NO. 4, 10-30% PASSING NO. 50, 0-10%
• PASSING NO. 100, 0-3% PASSING NO. 200
• 2. UNDERDRAIN SHALL BE 4' SLOTTED HOPE PIPE: SLOTS SHALL BE 1—X6
• • • • • • • LONG BY 0.032' WIDE, SLOT CENTERS AT 0.413•. 1.90 SQUARE INCHES OF
OPEN AREA PER LINEAR FOOT.
• 3. SEPARATOR FABRIC SHALL HAVE A GRAB STRENGTH OF 180 LBS (ASTM D
4632), A PUNCTURE AND TEAR RESISTANCE OF 70 LBS (ASTM D 4833 h
4887.60 4533), A PERMITTIVITY OF 0.02/SEC (ASTM D 4491), AND AN
ULTRAVIOLET DEGRADATION OF LESS THAN 50% AT 500 HOURS (ASTM D
• • 4$$6.75 4355).4. 18' GROWTH MEDIA LAYER SHALL CONSIST OF:
4.1. 7.5% CLASS 1 STA REGISTERED COMPOST (APPROXIMATE BULK
• DENSITY OF 1000 LBS/CY)
• • • 4.2. 7.5% LOOSELY PACKED SHREDDED PAPER (APPROXIMATE BULK
DENSITY 50 TO 100 LBS/CY)
• • • 4.3. 55% COARSE SAND (EITHER CLASS C FILTER MATERIAL (PER COOT) OR
ASTM C-33 SAND)
1 .. • • �'� 5. THE FILTER AREA SHALL BE SEEDED WITH NATIVE SEED MIX (NOT
• SODDED). z
„• \'� 6. 6' FILTER MATERIAL LAYER SHALL CONSIST OF COOT CLASS C FILTER g Q
. . • • • 4886.75 MATERIAL > (L
�• � w�
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CONCTNIRATCO NnOW
HEADWALL
OR HAIRED END SECDON
yl
w
0
ME
VE OR l RIPRM
Z F
Q
GEOTE[OlE SEPARATOR EADRK
O
U
y,0
�
^
•i
N
INPEINIOUS %�
--,A
-
f
V I vl
AEA
RNN GARDEN GROWING YEUM
Q
.- ..
COOT CLASS C FILTER
O
MATERIAL (FOR UNO(RLIRAR)
lJ
�
FILTER AREA (FLAT)
NTS
AODTIRYLAL DVOLUME
(OPFgNAL)
WOCV WISE
INLCI1N
DRAI[D INICT
m
I VEGETATED FILTER AREA
ELM
tits
ADr1ED CURB ORIFICE PULE TO DRAM
W OVER 12 NODRS
_
Figure B-1
wMm STOP
— Typical Rain Garden Plan and Sections
RNN GARDEN GROWING MECLA
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- WATER TIGHT CAP ON
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x.-6. ADDITIONAL CIMNr10H ORRICE (OPFIONAL)
A' SLOTTED PIPE PER TABLE 0-0, SLOPE TO OLITLO
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RAIN OWEN GROWING MEOIA
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(S7RNGHF GRADE) SIRIGRADE (x-1OS) TO UNDERORNN TO REDUCE
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SATURATED SOIL CONDRiONS BETWCEN STORY FVEMS (OPTIONAL)
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FILTER µATERIAL MELTING TABLE 0-7
FILTER MATERIAL MEEMC
TABLE B-x
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2
TYP 3
TYP
CELL 1
CELL 2
1
TYP CELL 3
CELL 4
CELL 5
\ CELL 6
BUILDING #3
5-PLEX
CELL 7
CELL 8
BUILDING #7
8-PLEX
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OCONSTRUCT 4' SLOTTED HDPE UNDERDRAIN AND LATERAL FLOW BARRIER, SEE
PERMEABLE PAVEMENT SECTION C—C.
CONSTRUCT STORMWATER VAULT, SEE PERMEABLE PAVEMENT DETAIL THIS SHEET.
CONSTRUCT 40 HDPE PIPE (NON —SLOTTED).
CELL 9
PERMEABLE
BUILDING #4
0' 10' 20` 40'
SCALE IN FEET
PAVEMENT NOTES
CLASS C FILTER MATERIAL SHALL BE GRADED AS FOLLOWS: 100%
PASSING �4 , 60-100% PASSING NO. 4, 10-30% PASSING NO. 50, 0-10%
PASSING NO. 100, 0-3% PASSING NO. 200
2. UNDERDRAIN SHALL BE 4' SLOTTED HDPE PIPE: SLOTS SHALL BE 1—Xe
LONG BY 0.032" WADE, SLOT CENTERS AT 0.413". 1.90 SQUARE INCHES OF
OPEN AREA PER LINEAR FOOT.
�-P� E/` / 3. SEPARATOR FABRIC SHALL HAVE A GRAB STRENGTH OF 180 LBS (ASTM D
4632), A PUNCTURE AND TEAR RESISTANCE OF 70 LBS (ASTM D 4833 h
4533). A PERMITTIVITY OF 0.02/SEC (ASTM D 4491), AND AN
ULTRAVIOLET DEGRADATION OF LESS THAN 50% AT 500 HOURS (ASTM D
4355).
4. CONTRACTOR SHALL INSTALL LATERAL FLOW BARRIERS OF IMPERMEABLE
GEOMEMBRANE PERPENDICULAR TO THE DOWN GRADIENT FLOW AT A
SPACING OF 40 FEET. GEOMEMBRANE SHALL BE 30 MIL THICKNESS (t5%
ASTM D 1593), WITH A TENSILE STRENGTH OF 70 LBS/IN (ASTM D 882,
METHOD B). THE LATERAL FLOW BARRIERS SHALL BE ORIENTED
VERTICALLY, AND SHALL EXTEND FROM THE TOP OF THE BASE COURSE
DOWN TO 6" BENEATH THE FILTER MATERIAL LAYER. PLEASE NOTE THAT
THE BARRIER SHOULD RUN PERPENDICULAR TO THE UNDERDRAIN, AND ~
NOT PREVENT DRAINAGE TO THE UNDERDRAIN. LL ZZ
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5. STORMWATER VAULT ORIFICE DIAMETER WALL BE 34 . w a
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6. EXCAVATION OF SUBGRADE SHALL NOT COMMENCE UNTIL AFTER THE d Q
PRE -CONSTRUCTION MEETING. L o
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C 7. SUBGRADE SHALL BE EXCAVATED USING LOW GROUND PRESSURE (LGP) w wo
TRACK EOUIPMENT TO MINIMIZE OVER COMPACTION OF THE SUBGRADE.* f Z
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8. GRADING AND COMPACTION EQUIPMENT USED IN THE AREA OF THE a
PERMEABLE PAVEMENT SHOULD BE APPROVED BY THE ENGINEER PRIOR
CELL 10 TO USE.
9. LOOSE MATERIAL SHALL NOT BE STORED ON THE PERMEABLE PAVEMENT
AREA.
10. THE CONTRACTOR SHALL, AT ALL TIMES DURING AND AFTER SYSTEM
/ INSTALLATION, PREVENT SEDIMENT, DEBRIS, AND DIRT FROM ANY SOURCE
FROM ENTERING THE PERMEABLE PAVEMENT SYSTEM.
11. PLACEMENT OF THE WEARING COURSE SHALL BE PERFORMED ALB FINE
GRADING AND LANDSCAPING IN ADJACENT AREAS IS COMPLETE. IF THE
WEARING COURSE BECOMES CLOGGED DUE TO CONSTRUCTION ACTIVITIES,
CLEAN THE SURFACE WITH A VACUUM MACHINE TO RESTORE THE
INFILTRATION RATE AFTER CONSTRUCTION IS COMPLETE.
FIGURE
*FOR PARTIAL AND FULL INFILTRATION SECTIONS ONLY. 1
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