HomeMy WebLinkAboutDrainage Reports - 08/15/2005City of Ff. Collins prov lans
Approved By
Date
Addendum to the Final Drainage & Erosion Control Report
For
Lots 1 & 2, Boardwalk Crossing, Filing 2
Located at
McClellands / Mail Creek Drainage Basin
Fort Collins, Colorado
February 20, 2013
Prepared for:
George Holter
3509 S Mason St.
Ft. Collins, CO 80525
Original Report Prepared by:
Stewart & Associates, Inc.
103 South Meldrum Street
Fort Collins, CO 80521
Phone: (970) 482-9331
Certified by:
Forbes Engineering LLC
2908 Cherly Street
Fort Collins, CO 80524
Phone: (970) 232-6014
1
FORBES ENGINEERING
' Full Service Civil & Structural Engineering
' February 25, 2013
Olen Schlueter
City of Fort Collins
' Stormwater Engineering
700 Wood Street
' Fort Collins, CO 80521
' RE: Drainage & BMP Certification for site improvements at
Boardwalk Crossing at Mason Street.
4012 So Mason St, Fort Collins, CO
' Mr. Schlueter,
' This letter and attached report is to serve as certification of the Addendum to the
Final Drainage and Erosion Control Report produced for Lots 1 & 2, Boardwalk
' Crossing, Filing 2 by Stewart & Associates, Inc., dated April 1, 2005 (a copy of
this report is attached with this letter and a copy of the original Final Drainage and
Erosion Control Report prepared for Nadine Holter can be produced if required).
' The Boardwalk Crossing site improvement project is located at the Northeast
' corner of Mason Street and Boardwalk Drive. The improvements to the site
include the construction of two commercial buildings along with the required site
improvements. The proposed improvements remain the same the previously
' approved project but for the increase of 2,000 square feet to the southwestern
office/retail building. This additional building's roof area will be off -set by the
' decrease in pavement area which has a higher run-off coefficient than the roof so
the projected run-off will decrease by a very small amount.
' As with the original report, the storm water quality will be maintained using Best
Management Practices as outlined in the report and with construction methods as
' shown on the Utility Construction Plans.
All proposed drainage patterns and sub -basins remain the same as the original
' design. A grass island has been designed for the extended detention and all runoff
will be directed to the existing 30 inch RCP located within Boardwalk Drive
' which was constructed for the McClellands/Mail Creek Drainage Basin.
Runoff from this site will be restricted to 0.87 CFS per acre as allowed by the
McClelland/Main Creek basin. Storm Drainage facilities required for this
development include an extension of the 12 inch ADS pipe, a water quality control
structure with a pond outlet restriction plate as well as the extended detention
restriction plate and a four foot concrete pan to allow flow from South Mason
Street via a curb and sidewalk chase.
Adjustment to the original report's City Erosion Control Escrow to match current
prices is as follows;
Erosion Control Cost Estimate
1. Silt Fence:
2. Gravel Filter:
3. Straw Bale Filter
900 LF @ $3.50/Ft
= $3,150
2 @ $200
= $400
1 @ $150
= $150
Total = $3,700
With an uncertainty factor of 1.5, the required City Erosion Control Escrow
Amount is $5,550
The conclusion of the storm drainage report & system review for this project is
that it was completed in accordance with the criteria set forth in the Larimer
County Stormwater Design Standards and the USDCM. The design conforms to
the drainage basin design of the Mail Creek Master Plan Update as well as the
City of Ft. Collins Design Criteria and Construction standards and that no adverse
affects to surrounding properties are anticipated from the proposed improvement
of this site.
Sincerely, p,OO .RED
0� N O9 ' .t11
��
V, (POJ
35265
evin Forbes, P.E. #35
2
I
ADDENDUM TO THE FINAL DRAINAGE AND EROSION CONTROL REPORT
FOR
LOTS 1 AND 29 BOARDWALK CROSSING, FIIJNG 2
LOCATED IN THE MCCLELLANDS / MAU, CREEK DRAINAGE BASIN
PREPARED FOR
NADINE HOLTER
April 1, 2005
PREPARED BY
STEWART & ASSOCIATES, INC.
P.O. BOX 429
103 SOUTH MELDRUM STREET
FORT COLLINS, COLORADO SM22
TEL: 970.482.9331
FAX. 970.482.9382
VICINITY MAP
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' STEWAU&ASSOCIAT'ES
Consulting Engineers and Surveyors
1
' April 1, 2005
Mr. Basil Hamdan
' Stormwater Utilities
City of Fort Collins
P.O. Box 580
' Fort Collins, CO 90522-0580
Re: Boardwalk Crossing at Mason Street
' We are proposing to develop Phase 11 of Lots 1 and 2, Boardwalk Crossing Filing 2. A bank
building along with the parking lots West and also South of the building that we constructed in
1997. This phase will be to construct the South and North buildings and the parking lot between
' them along Mason Street. The buildings and parking lot have been revised to our present need.
These changes however are minimal from the original design.
' This addendum is to update the original design calculations and erosion control methods to the
City Current Standards. Most design and calculations within this report are in compliance with
the City of Fort Collins Strom Drainage Criteria and Construction Standards. The one design
exception is the detention pond depth in the parking lot exceeds the City Standard of 12-inch
depth by 0.1 to 0.2 feet at the flow line of the curb around the water quality control island in the
middle of the parking area We are asking for a variance because this flow line area is not either
' a walking or parking area In fact at the lip of the gutter, which is two feet wide, we meet the
City criteria of 12" of depth. This area that exceeds your standard is very small and does not
affect heahh, safety, or welfare of this project.
If you have any questions or comments regarding this report, please let me know.
Sincerely,
' Franklin D. Blake, P.E. & L.S.
' FDB/meh
James H. Stewart and Associates, Inc.
' 103 S. Meldrum Street • P.O. Box 429 • Ft. Collins, CO 80522
970/482-9331 • Fax 970/482-9382
April 1, 2005
ADDENDUM TO THE FINAL DRAINAGE AND EROSION CONTROL REPORT
FOR
LOTS 1 AND 29 BOARDWALK CROSSING FILING 2
EXISTING SITE:
This site was originally designed in 1996 and the bank building and the parking lots on the West
and South sides of the bank constructed in 1997. The developed site was constructed as the
designed grading, drainage and erosion control plan show on Sheet 4 of 5 of the Approved
Utility Plan. That sheet is included herein along with the original drainage report for reference.
' All lots and roads around this phase have been constructed. The sine is bounded on the North by
Boardwalk Avenue on the East by the bank's parking lot and REI; on the South by a 30-foot
wide access road; and on the West by South Mason Street.
Runoff from this site will be as originally designed which will be to route all runoff to the
Stormwater System in Boardwalk Drive which was constructed for the McClelland / Mail Creek
basin. Runoff from this site will be restricted to 0.87 c1s. per acre as allowed by this basin. The
S.I.0. fee for this project was paid for at the time of the bank construction
DESIGN CRITERIA:
The rational method will be used to determine the developed site initial and mayor storm runoff
Detention for the site will be based on the 100-year storm less the allowed release rate of 0.87
c.f s. per acre. The mass diagram will be used to determine the required detention. All
calculations and design consideration are in accordance with the City of Fort Collins Design
Criteria Manual, except the historic 2-year storm will not be used for the release rate.
DEVELOPED SITE:
All proposed drainage patterns and subbasins remain the same as the original design This phase
is in Sub -basins A, D, and part of C. Sub -basins C and D are existing except for the North
proposed building and c not be changed with this projecL Sub -basin 4 which includes offsite
flows from Mason Street will be designed to inchude the City's new intensity data and extended
detention. A grass island has been created for the extended detention.
All runoff from this Phase 2 will be to the existing 30 inch R.C.P. storm drain in Boardwalk
Drive which was constructed f+or the McClellands/Mail Creek Drainage Basin. This pipe system
outf tUs into Marl Creek.
Storm Drainage facilities required for the Phase 2 will be the extension of the 12-inch A.D.S.
pipe. The water quality control structure with the pond outlet restriction plate and also the
extended detention restriction plate. The four -foot concrete pan to allow flow from, South Mason
Street and the sidewalk chase.
EROSION CONTROL:
This site is in a moderate to high rainfall erodibility zone and in moderate to high wind
erodibility zone. Rainfall performance standard evaluation and effectiveness calculations were
' completed with the original report and have not changed The required City Erosion Control
Escrow Amount is $2950.
' This phase will construct a silt Bence along the North and South property lines and on the East
Property line along the REI site and also along the West line of the exsting West parking lot, and
along South Mason Street. A gravel filter shall be placed around the eAstiog area inlet in the said
' West parking lot and also around the area inlet on the South parking lot of the bank. A straw bale
barrier shall be placed around the WQC structure in the grass island
I STORM DRAINAGE
CALCULATIONS
STE V VAR &kSSOCIA ES 10 S. 9 3DRF� FO TTCCOLLINS, CO 80521
PH. 481 482-2
Consulting Engineers and Surveyors �/�
By: /aa� _ Date: //O/O�/ Client: //'a/O/0d' 4 45y- Sheet No. of —
Project
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STEWART& SSOC[ATES 103 S. MEL9331DRUM,FAX FORT 8OLLINS, CO 80521
Consulting Engineers and Surveyors
By: 1 Date:-.7''0✓� Client: /`T��� Sheet No. �c� of
Project: 407 5 for
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DRAINAGE CRITERIA MANUAL
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VELOCITY..
FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR
USE WITH THE RATIONAL FORMULA.
*MOST FREQUENTLY OCCURRING"UNDEVELQPED"
LAND SURFACES IN THE DENVER REGION.
REFERENCE: "Urban Hydrology For Small Watersheds" Technical
Release No. 55, USDA, SCS Jan. 1975.
' 5 -1-84
URBAN DRAINAGE 3 FLOOD CONTROL DISTRICT
1-y
T
City of Fort Collins
Rainfall Intensity -Duration -Frequency Table
for using the Rational Method
(5 minutes - 30 minutes)
Figure 3-1a
Duration
(minutes)
2-year
Intensity
in/hr
10-year
Intensity
in/hr
100-year
Intensity
in/hr
5.00
2.85
4.87
9.95
6.00
2.67
4.56 '
9.31
7.00
2.52
4.31
8.80
8.00
2.40
4.10
8.38
9.00
2.30
3.93
8.03
10.00
2.21
3.78
7.72
11.00
2.13
3.63
7.42
12.00
2.05
3.50
7.16
13.00
1.98
3.39
6.92
14.00
1.92
3.29
6.71
15.00
1.87
3.19
6.52
16.00
1.81
3.08
6.30
17.00
1.75
2.99
6.10
18.00
1.70
2.90
5.92
19.00
1.65
2.82
5.75
20.00
1.61
2.74
5.60
21.00
1.56
2.67
5.46
22.00
1.53
2.61
5.32
23.00
1.49
2.55
5.20
24.00
1.46
2.49
5.09
25.00
1.43
2.44
4.98
26.00
1.40
2.39
4.87
27.00
1.37
2.34
4.78
28.00
1.34
2.29
4.69
29.00
1.32
2.25
4.60
30.00
1.30
2.21
4.52
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CURB OPENING INLET IN A SUMP 71
Project =
Inlet ID =
WP Lu WP
H
Cutter
i Yd
Pan
water
Flow Direction
th of a Unit Inlet
L„ =
4.00 ft
I Depression, if any (not part of upstream Composite Gutter)
81.d =
2.00 inches
it of Curb Opening in Inches
H =
6.00 inches
Width for Depression Pan
WP =
3.00 ft
ding Factor for a Single Unit (typical value = 0.1)
C. =
0.10
D of Throat (see USDCM Figure ST-5)
Theta =
63.4 degrees
a Coefficient (see USDCM Table ST-7)
Cd =
0.67
Coefficient (see USDCM Table ST-7)
Cw =
2.30
Number of Units in the Curb Opening Inlet
No =
1
a Weir
sign Discharge on the Street (from Street Hy)
Q, =
5.2 cfs
ter Depth for the Design Condition
Yd =
5.81 inches
al Length of Curb Opening Inlet
L =
4.00 ft
Dadty as a Weir without Clogging
Q„d =
7.3 cis
g8mg Coefficient for Multiple Units
Coef =
1.00
ggfng Factor for Multiple Units
Clog =
0.10
patty as a Weir with Clogging
a. =
7.0 cfs
an Mice
pally as an Orifice without Clogging
Qa =
5.5 cis
pacity as an Orfice with Clogging
06 =
4.9 cfe
pacity for Deslan with Cloaalna
01 =
4.9 cis
pture Percentage for this Inlet o Q, / Qo =
C% a
94.65 %
Note: Unless additional ponding depth or spilling over the curb is acceptable, a capture
percentage of less than 100% In a sump may Indicate the need for additional inlet units.
UD4nletvl.06a.xis, Curb-S
2/10/2005, 10:43 AM
STEWART&ASSOCIATES 103 S. MELDRUM, FORT COLLINS, CO 80521
Cosu tI ' PH. 482-9331 FAX 482-9382
' n7ng Engineers and Surveyors
BY Date: . -- Client: �� / ShFt Nn
' Project:
Subject:
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' STE VAffr&A SJVCIIA'T'ES 103 S. MELDRUM, FORT COLLINS, CO 80521
' Consulting Engineers and Surveyors PH. 482-9331 FAX 482-9382
By: 0-0/Date: - G Client: �11Sheet No. -5- of _
1 Project: _ L_ 41741 g- P/�ZSC 2
Subject:o
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DETENTION POND HIGH WATER LINE
EXTENDED DETENTION
CONTOUR AREA AVERAGE AREA INTERVAL CUMULATIVE HIGH WATER
(sq.ft.) (sa.ft.) VOLUME (ruft) VOLUME (cu.ft. p
I t±-L ) LINE_M)_ 7
DETENTION POND HIGH WATER LINE
INCLUDES EXTENDED DETENTION
VOL. = 1/3 (AREA ABOVE) (DIFFERENCE IN COUNTOUR ELEV.)
2. FOR THE REMAIMDER OF THE VOLUMES BETWEEN CONTOURS (SECTION 9.2)
VOL. = DEPTH/3 (A +(AB) '.5 + B) FOR: Uniform Sides sec.(9.2)
3. HWL= (VOL. REQ. —VOL.LOW CUML)*3/(AREA LOW+AREA HIGH+(Iow area*high area)
ORIFICE SIZING
IORIGINAL DESIGN DATA
' 1 *21 = Allowable Des. Re@4i�L
1
3 32.11 = Flowline Orifice Elevation (ft)
32 . 1 1
0 .6
0.65 Orifice Coefficient (Cd)
3.87 = Available Driving Head(ft)
VERT. CIRCULAR PLATE
_�17A2 = _OufttAeOg(i�OJM1168)
Z35 = Circular rad
368 = Actual Hvdraulic Drivingft Head ft
-VERT. SQUARE PLATE
17.36 =Outlet AreaN. riches
4.17 = Side for Sq. Openin
3.70 = Actua],Hydrauhc Orly iqg fiead,(ffl
NOTE: 1. VERT. PLATES WILL BE PLACED
AT PIPE FLOWLINE
r 0
EMERGENCY SPILLWAY DESIGN
Weir Equation Q = C L (H) ^ 3/2
Q (cfs), C (weir coefficient), L (crest length, feet), H (energy head, feet)
22 = Weir Length L in feet
3.1 = Weir Coefficient
Weir Shape Broadcrested
Design Flow 13.53 (cfs)
Depth of
flow ft
Flow Over Weir
cfs
0.10
2.16
0.15
3.96
0.16
4.36
0.17
4.78
0.18
5.21
0.19
5.65
0.20
6.10
0.30
11.21
0.40
17.25
0.50
24.11
4�1.35
CONSTRUCTKM PHASE okuk Month) 1 2 1 3 4 5 5 7 18 . _ ...9
___ _ ______
DRAINAGE CRITERIA MANUAL
RUNOFF /D
Q'
31
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W
a
0 5
to
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opt 3
0
0 2
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f•-
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1
.5
VELOCITY IN FEET PER SECOND
FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR
USE WITH THE RATIONAL FORMULA.
*MOST FREQUENTLY OCCURRING "UNDEVELOPED"
LAND SURFACES IN THE DENVER REGION.
REFERENCE: "Urban Hydrology For Small Watersheds" Technical
Release No. 55, USDA, SCS Jan. 1975.
5 -1-84
URBAN DRAINAGE & FLOOD CONTROL DISTRICT
1
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1
1
1
1
City of Fort Collins
Rainfall Intensity -Duration -Frequency Table
for using the Rational Method
(5 minutes - 30 minutes)
Figure 3-1a
in 2-year
(minutes) Intensityyear
10-year 100-
in/hr
Intensity Intensity
5.00 2.85
in/hr in/hr
4.87
F Fin ., , ,
9.95
7.00
8.00
9.00
10.00
11.00
12.00
13.00
14.00
15.00
16.00
17.00
18.00
21.00
22.00
8.38
Z•.Z1
3.78
7.72
2.13
3.63
7.42
2.05
3.50
7.16
1.98
3.39
6.92
1.92
3.29
6.71
1.87
3.19
6.52
1.81
3.08
6.30
1.75
2.99
6.10
1.70
2.90
5.92
1.65
2.82
5.75
1.61
2.74
5.60
1.56
2.67
5.46
1.53
2.61
5.32
1.49
2.55
5.20
1.46
2.49
5.09
1.43
2.44
4.98
1.40
2.39
4.87
1.37
2.34
4.78
1.34
2.29
4.69
1.32
2.25
4.60
1.30
0 1),
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to, 11
DRAINAGE CRITERIA MANUAL N. 3)
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UDFCD
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STORMWATER QUALITY MANAGEMENT
Note: Watershed inches of runoff shall to the
enff►e watershed teutary to the 88a Faddy.
FIGURE 5-1. WATER QUALITY CAPTURE VOLUME (WOCV)
DRAINAGE CRITERIA MANUAL (V. 3) STRUCTURAL BMPS
10.
6.1
4.1
2
1.i
0.6(
.2
o.4C
D.2c
a
o.0
3
Q 0.0E
0.00
oA
Irl
"SOLUTION: RZqul�,d A, la r
Zw .75 inrjpr
t
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NINE
FRA
No
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911A
lip
a,
E
ME
VOYANAVAINAF
PAJ
FJJ
F4
APA
V, A,
I OFA
11 ANA
ENIEll
%
NMIill
0.01
• 0.40 0.60 1.0 20 4.0 6.0
Required Area per Row (In?
Source: Douglas County Sturm Drakage and Tedmkd Crirerk IM.
FIGURE 5-3. WATER QUALITY OUTLET SIZING: DRY EXTENDED DETENTION
BASIN WITH A 40-HOUR DRAIN TIME OF THE CAPTURE VOLUME
9-1-1992
UDFCO
' DRAINAGE CRITERIA MANUAL (V 3)
STRUCTURALBMPs /7
' Threaded Cap
Water Quality Capture Volume
' Level (including 20% additional
volume for sediment storage)
Gravel (1-1/2'to
3' Rock) Around
?erfcrated Riser
Filter Fabric
Water Quality
Riser Pipe (See Detail)
Notes: 1. The outlet pipe shall be sized to control
overflow into the concrete riser.
2. Alternate designs Ind ude a
Hydrobrake outlet (or orifice
designs) as long as the hydraulic
Performance matches this
configuration.
Notes: 1. Minimum number of holes . 8
2 Minimum hole diameter. 1r8'da.
Access Pit
(Min. 3 ft)
OUTLET WORKS
NOT TO SCALE
1-12' diameter Air
Vent in Threaded C
Water Quality
Outlet Holes
Ductile Iron or
Steel Pipe
rER QUALITY
RISER PIPE
NOT T -SCALE
S-4-
Removable & Lockable
Overflow Grate for
Larger Storms
Outlet Pipe --►
Size Base to Prevent
Hydrostatic Uplift
Maximum Number of Perforated Columns
Riser Hole Diameter, in.
Diameter
(m') 1/4' 1/2' 3/4' 1'
4 8 8
6 12 12 9
8 16
16 12 g
10 20
20 14 10
12 24
24 18 12
Hole Diameter
Area of Hole
(in.)
(in.2 )
14
0.013
1 14.
3/
0.049
1/22
0.110
SIB0.307
0.196
3/4
Ire
0.442
1
0.601
0.785
FIGURE 5-2. WATER QUALITY OUTLET FOR A DRY
9-1-1992 EXTENDED DETENTION BASIN
UDFCD
`+B • L3
STEWART&kSSOCIATES 103 S. MELDRUM, FORT COLLINS, CO 80521
Consulting Engineers and Surveyors ' PH. 482-9331 FAX 482-9382 By: �Gh Date: 7" �.� Client: /TD11/ Sheet No. 125rof—
Project: EJo�/�/fJ9�� 4 �Oylw% /� O/l
Subject:.�051D/J
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A SET FENCE 5 REOUWED ALONG
THE EAST PROPERTY Li OF LOT 2
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BMP NOTES:
SILT FENCE TO BE PLACED PRIOR TO AND
CONSTRUCTION AND REMAIN IN PLACE UNTIL
ALL CONSTRUCTION IS COMPLETE
CONSTRUCT STRAW BALE DIKE AROUND WATER
QUALITY STRUCTURE AND IT SHALL REMAIN
` IN PUCE UNTIL CONSTRUCTION IS COMPLETE.
-G"• CONSTRUCT GRAVEL FILTER AROUND EXISTING
AREA INLET IN PARKING LOT M BASIN C Ai ON
BANK INLET BY TRASH ENCLOSURE PRIOR TO THE
BEGINNING OF CONSTRUCTION AND REMAIN UNTILL
CONSTRUCTION 15 COMPLETED.
NOTE
The top of foundation elevations shown
are minimum elevations required for
protection from the 100 year storm.
Minimum finished floor elevations above
the 100 year water surface in streets,
channels, ditches, swales, or other
drainage facilities as illustrated by o
master grading plan are to be shown.
BASIN DATA:
SITE AREA 1.39 ACRES
HISRMYC DATA —
Q2
I
aim
2.60
645
11.J0
POND RELEASE RATE = 0.87 ch/ocre
CONSTRUCTION SEQUENCE
NM Gar tin, vrwn cwwWN'an •d eavnr aM Men &Ve W N NNa40/rwwW b fM
inn gives, I IF III I
1 11
Z'
O
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—
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■■■■_■_■_■_
lilt=iiii
POND DATA:
- Repuimd retention WNme 9,805 cf
Required Extended Detention Volume X139 If
yg
Siro Required Detention Volume 11844 IF
Pend Contour Volume
Contour 5032.1 0 OF
Contour 5033 51 cf
Contour 5034 J755 cf
W
Contour 50J5 2.J40.4 cf
Contour i 120I1.6 Of
y
Contour 50361 IJlO4J cf
Pond1
Top of Pond
= p
50.
100 Year 50J60
Extended Detention HWL = 50J4.8 2
Flawlriro of Pond W32,1 t sic
IS g
Rii of of Pipe 503211
Top of bock of Water Ou nity Control Sfuctum — 50353 O
Top of hoot of water Quality cannot strvctun — 51 Z
ReeMcnlan Plate Opening Sze 4.2 diameter al & Ny O
Extended Detention Plate Opening Sze J/6' diameter hole per rov, (h
Rows arc spaced 4 apart vertically 9 R isa
W
3 Y
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL g
APPROVED: g
a+i bngawv pw
CHECKED BY.. ilk r O
/sew a IrmY•N� uavy 11H � v
SCALE.' 1 ii = 30 CHECKED BY.. s>ainw.W. vas IT
DOE
JO 0 JO w 80 CHECKED BY: : wrr/m
CHECKED BY:CHECKED BY.. or B
bW