HomeMy WebLinkAboutDrainage Reports - 05/22/2007City of Ft Collins P s
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March 13, 2007
I NTERWEST C O N S U IIING GROUP
Mr. Basil Hamdan
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80522
Re: The Center at Rigden Farm Fourteenth Filing — Final Drainage Report
Dear Basil,
1 Please accept the following letter report on behalf of The Center at Rigden Farm to demonstrate
the site's compliance with the previously approved Final Drainage Report for Rigden Farm
Filing Six, as prepared by JR Engineering.
INTRODUCTION
The site, Rigden Farm Fourteenth Filing, contains 4.08 acres and is bounded on all four sides by
existing city streets, namely Custer Drive, Illinois Drive, Iowa Drive and Limon Drive. The site
is bisected by a previously constructed storm drainage pipe which outlets in an existing detention
pond which is referred to as Pond 212. The design for this pond was referenced in the Filing Six
report stating that "Pond 212 was sized in the O.D.P. and will be constructed with Filing Eight".
All detention and water quality requirements for this site have been met by the overall Ridgen
Farm development.
Rigden Farm Filing Six updated the basins. in the vicinity, of this.pond based upon anticipated
ultimate development; however, the original pond sizing (stage -storage) was not altered. Filing
Six did update the SWMM model using the updated basin information; however, the EXTRAN
model was not re -run with that Filing. Excerpts from the Filing Six report are attached for
reference. The Filing Six updated SWMM model shows that the peak storage of Pond 212
during a 100-year storm event is 0.8 acre-feet. Please refer to Appendix A for excerpts from the
Filing Six Drainage Report and the SWMM model. The original intent was to create an 80'
drainage easement with a drainage ditch. The 80' drainage easement was dedicated; however,
the ditch was replaced with a series of pipes constructed with Filing Eight. The existing 80'
drainage easement will be vacated via the plat for this project, and replaced with a smaller
easement varying in width approved by the City.
EXISTING CONDITIONS
The site is currently vacant and contains dirt, and dry shrubs. The existing site also includes two
existing storm drain pipes. A 36" RCP storm pipe enters the site from the west and connects to
the 42" RCP at an existing junction box near the proposed driveway entrance off Illinois Drive.
1218 W. ASH, STE. C • WINDSOR, COLORADO 80550
TEL.970.67A.3300 • EAx.970.674.3303
1
Mr. Basil Hamdan
March 13, 2007
Page 2 of 5
An existing 18" RCP with an area inlet entering the junction box from the north will be removed
with the proposed development. The site drains in three distinct directions and the general basin
' lines, as proposed in the SWMM model, have been maintained with the proposed development
and in conformance with the Ultimate Development basin delineations as shown in the Rigden
Farm Filing Six Final Drainage Report.
' PROPOSED DEVELOPMENT
' The proposed development will include the construction of eleven commercial buildings, a large
on -site parking area, on -site sidewalks and landscape areas. Please refer to Appendix B for the
Drainage and Erosion Control Plan and hydrologic computations.
' BASIN DESCRIPTIONS
The site is divided into seven basins: A1, A2, A3, A4, A5, A6 and AT
Basin Al is comprised of drainage from half of the roofs of Lots 1, 2, 10 and 11, over a third of
1 the drainage from the parking lot, on -site sidewalks and landscape areas. Water will flow from
the roof drains into sidewalk chase drains and sheet' flow over the proposed parking lot into a
Neenah Triple R-3406 drainage inlet. Water from the on -site sidewalks and landscape areas will
flow via sheet flow into the proposed parking lot and into the proposed inlet. 'From the inlet,
water will be transported via storm drain pipe to the existing storm drain system near the center
of the property.
Basin A2 is comprised of a portion of roof drainage from Lot 3, half of the roof drainage from
Lot 9, about a third of the drainage from the parking lot, on -site sidewalks and landscape areas.
Water will flow from the roof drains into sidewalk chase drains and sheet flow over the proposed
parking lot into a Neenah Double R-3406 drainage inlet. Water from the on -site sidewalks and
landscape areas will flow via sheet flow into the proposed parking lot and into the proposed inlet.
' In addition, water will flow from the proposed driveway entrance on Iowa Drive via curb and
gutter to a transition point in the parking area, then sheet flow into the proposed inlet. From the
inlet, water will be transported via storm drain pipe to the existing storm drain system near the
' center of the property.
Basin A3 is comprised of half of the roof drainage from Lot 8, about a third of the parking lot
' drainage, on -site sidewalks and landscape areas. Water will flow from the roof drains into
sidewalk chase drains and sheet flow over the proposed parking lot into a Neenah Double R-
3406 drainage inlet. Water from the on -site sidewalks and landscape areas will flow via sheet
flow into the proposed parking lot and into the proposed inlet. From the inlet, water will be
transported via storm drain pipe to the existing storm drain system near the center of the
property.
Hydraulic calculations for sizing the proposed stormwater inlets and pipe discussed in Basins
Al, A2, and A3 were completed using StormCAD hydraulic modeling software. The 100-year
Mr. Basil Hamdan
' March 13, 2007
Page 3 of 5
storm was analyzed to insure that the parking lot functions with minimal flooding. Please refer
to Appendix C for inlet sizing and StormCAD output data.
' Basin A4 is comprised of roof drainage from Lots 4, 5, 6, 7, a portion of roof drainage from Lots
8, 9, 10; on -site sidewalks, two large landscape areas and a small portion of the access drive off
' Iowa Drive. On the west side of the basin, water from the roof drains will enter the flowline on
the Illinois Drive via sidewalk chase drains. Water from the sidewalk will sheet flow into the
flowline. Once entering the flowline on Illinois Drive, water will be transported to existing inlets
1 via curb and gutter and into the storm drain system along Custer Drive. Drainage from the south
side of the basin will enter the flowline on Custer Drive via sidewalk chase drains and sheet flow
across the sidewalk and landscape areas. From the flowline, water will be transported via curb
' and gutter into the existing storm drain system on Custer Drive. The east side of the basin will
also include sidewalk chase drains and sidewalk sheet flow to channel the water into the flowline
on Iowa Drive. Once in the flowline on Iowa Drive, water will be transported via curb and gutter
and street sheet flow to the existing storm drain system on Custer Drive.
Basin A5 and A6 includes half of the roof drainage from Lots 2 and 3 respectively, on -site
I sidewalks and landscape areas. Water from the roof drains will enter the flowline on Illinois
Drive via sidewalk chase drains. Water from the sidewalk and landscape areas will sheet flow in
to the flowline. Once in the flowline on Illinois Drive, water will be transported via curb and
gutter into existing storm drain inlets included in the storm drain system near the center of the
property.
' Basin A7 is comprised of a portion of roof drainage from Lot 10, half of the roof drainage from
Lot 11 and on -site sidewalks. Water from the roof drains will enter the flowline on Iowa Drive
via sidewalk chase drains. Water from the sidewalk will sheet flow in to the flowline. Once
' entering the flowline on Iowa Drive, water will be transported via curb and gutter to the existing
storm drain system on Limon Drive.
Summary: Filing Six similarly utilized an "Ultimate Development" condition for the basins that
make up the proposed site. All area contained within the site were assumed to be Commercial or
Multi -Family with an imperviousness of 80% used for the middle basin (SWMM Sub basin 582)
and 90% for both the north and south basins (SWMM Sub basins 581 and 58). The north and
middle basins flow into the existing storm drain system near the center of the property. The
weighted average site imperviousness for the combined basins is 86%. The combined basin
corresponds to Basins Al, A2, A3, A5 and A6 on the proposed drainage plan. The weighted
average site imperviousness for the five basins on the plan is also 86%. The south basin
corresponds to Basin A4 on the proposed drainage plan. Basin A4 has a 59% impervious; which
is well below the 90% impervious called out in the SWMM model. Therefore, it is requested
that the site be deemed in substantial conformance with the previously approved Final Drainage
Reports.
EROSION CONTROL
Mr. Basil Harridan
' March 13, 2007
Page 4 of 5
' Erosion control calculations for during construction and post -construction have been performed
and the output is located in Appendix D.
' Erosion and sedimentation will be controlled on -site by use of silt fences, area inlet protection, a
gravel construction entrance, and seeding and mulch. The measures are designed to limit the
' overall sediment yield increase due to construction as required by the City of Fort Collins.
During overlot and final grading the soil will be roughened and furrowed perpendicular to the
prevailing winds.
' During the performance of the work required by these specifications or any operations
appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the contractor
1 shall furnish all labor, equipment, materials, and means required. The Contractor shall carry out
proper efficient measures wherever and as necessary to reduce dust nuisance, and to prevent dust
nuisance that has originated from his operations from damaging crops, orchards, cultivated
fields, and dwellings, or causing naissance to persons. The Contractor will be held liable for any
damage resulting from dust originating from his operations under these specifications on right-
of-way or elsewhere.
' It is unlawful to track or cause to be tracked mud or other debris onto city streets or rights -of -
way. Wherever construction vehicles access routes or intersect paved public roads, previsions
' must be made to minimize the transport of sediment by runoff or vehicles tracking onto the
paved surface. Stabilized construction entrances are required with base material consisting of 6"
coarse aggregate. The contractor will be responsible for clearing mud tracked onto city streets
on a daily basis.
All temporary and permanent erosion and sediment control practices must be maintained and
' repaired as needed to assure continued performance of their intended function. Silt fence will
require periodic replacement. Maintenance is the responsibility of the contractor. The
Contractor shall obtain and comply with a CDPHE Stormwater Discharge Permit.
' All disturbed areas must be seeded and mulched within 30 days of project start. Vegetation shall
not be considered established until a ground cover is achieved which is demonstrated to be
' mature enough to control soil erosion to the satisfaction of the City Inspector, the Permit and to
survive severe weather condition.
tIf you have any questions or comments please contact me at (970) 674-3300.
' Sincerely,
X-'4
1 Robert Almirall, P.E.
Colorado Professional Engineer 33441
r
Mr. Basil Hamdan
'
March 13, 2007
Page 5 of 5
Attachments
I
1
APPENDIX A
Excerpts from Previous Drainage Reports
I FROM" FINAL DRAINP%G& AND ER0610N CONTROL REPORT RIDDEN FARM - FILI N(j 61)("
K = headloss coefficient
V = average velocity (ft/s)
g = gravitational constant (32.2 ft/s2)
The storm pipe design was performed for the ultimate build -out of Rigden II in all three
parcels and is included in Appendix E of this report.
5. REGIONAL HYDROLOGY
5.1 Methods and Approach
The hydrology for Rigden II, as in the O.D.P., was evaluated using an integrated
UDS WMM2PC, MODSWMM. The original Master Plan SWMM model was developed by
Resource Consultants Inc. in 1981. An updated Master Plan model was completed by
Faucett Engineering in 1997 using the then -current 100-year rainfall depth (2.89" of rain for
the 100-year, 2-hour storm). An update to the Master Plan SWMM model was completed by
Anderson Consulting Engineers, Inc. (ACE) in July 1999. The "Overall Drainage Report for
the Rigden Farm O.D.P." (Feb. 1999) was developed concurently with the ACE model and
includes Rigden Farms ultimate conditions. The Rigden O.D.P. model was used as a basis for
the SWMM model for this study because it incorporates the most up to date information for
J
the Foothills Basin and Rigden Farm.
5.2 Development of SWMM Model
The SWMM model for Rigden II revises the basin parameters to match the proposed
improvements. Minor changes were made to sub -basins 58, 65, 66, 67, 68, 69, 581, 582, 584,
and 681 of the Rigden O.D.P. model. Sub -basins 671, 691, and 682 were added. The
conceptual storage -discharge rating curve for Detention Pond 216 was modified to reflect
proposed grading and Detention Pond 269 was added in Basin 69. The total basin area for
Rigden Farm in the Rigden 11 model is 315.9 acres, 0.7 acres less than the Filing One model.
This difference is due to changes in basin boundaries along Drake Road and Timberline
Road. A copy of the SWMM Model Sub -basin Delineation is included in Appendix F of this
report.
Drainage,and Erosion Control Report Page 17
Rigden Farm — Filing Six February 8, 2002
The values recommended by the City of Fort Collins were used for the percent
imperviousness. These values were also close to the estimated values for the Rigden Farm
development. For commercial areas, a percent impervious value of 90% was used and for
multifamily areas, 70% of the area was assumed impervious. For single family residential
sub -basins, 45% of the area was assumed impervious. Basin widths were calculated based
on an average overland flow path length that varies. according to land use. For undeveloped
basins, the overland flow path is estimated to be between 100 ft and 500 ft depending on the
' topography. For developed basins, the overland flow path is estimated to be between 50 to
300 ft. The following table summarizes the basin parameters for the Rigden H model.
Tnhla S 1 - SWMM Rnhhnein Pnrnmatare fnr Illtimnta ❑avalnnmant
SWMM
Subbasin
Basin Width'
W
k
Area
ac.
Overland flow
Path, L
ft
% Impervious
Slope
°/.
Basin Description
58
6000
41.1
298
90%
1.0%
Commercial
581
3450
22.4
283
90%
0.8%
Commercial
582
1700
11.5
295
80%
2.0%
Multi -family & Commercial
583
1 400
2.5
1 267
70%
2.0%
Multi -family
584
2900
19.7
296
90%
1.5%
Dense multi -family & commercial
65
1200
4.0
145
10%
3.0%
Adjacent to. Regional Channel
66
4900
15.1
134
12%
2.0%
Adjacent to Regional Channel
67
10400
99.2
415
45%
2.0%
Single Family
671
2300
8.3
157
19%
10.0%
Adjacent to FCRID
68
2400
25.2
457
45%
1 2.0%
Single Family
681
640
6.0
408
1 57°
1.5%
Single Family
682
500
3.5
305
45%
1.5%
Single Famil
69
goo
53.5
402
45%
1.9%
Single Family
691
1700
1 3.9
1 100
1 31%
1 10.0%
Adjacent to FCRID
WWI dlwd= a 10.-J du
5.3 Pond Description
' Six ponds will be. provided for Rigden H. Two primary water quality/detention ponds will be
located in the northeast and southeast comers of the site. Three water quality ponds will be
' located south of the Foothills Regional Channel. A detention pond will be located in the
Northwest Roads area.
' Water quality/detention Pond 216 will be north and east of the improved Drake and Ziegler
' Roads and water quality/detention Pond 269 will be south of Rigden Parkway and west of
Ziegler Road. Both Ponds 216 and 269 will be large wet ponds with detention volume
available above the permanent water surface elevation. The detention ponds will have water
Drainage and Erosion Control Report Page 18
t Rigden Farm — Filing Six February 8, 2002
quality outlet structures and sedimentation forebays. The outlet for Pond 216 will be an
inverted siphon under the Boxelder Ditch, the Fossil Creek Reservoir Inlet Ditch (FCRID)
and the existing Ziegler Road. Pond 216 replaces two temporary detention ponds (Ponds 221
& 222) constructed with Rigden Filing One. The outlet for Pond 269 will be a'8-foot by 4-
foot box culvert under the proposed Ziegler Road into FCRID.
Water QualityPonds 1, 2, and 3 will store Rigden II runoff for water quality purposes before
releasing it to the Foothills Regional Channel. Pond 1 will be located just west of Rigden
Parkway and Pond 2 will be located just east of Rigden Parkway. Pond 3 will be located just
east of Chase Drive.
Detention Pond 212 was sized in the O.D.P. and will be constructed with Rigden Farm —
Filing Eight. The pond has been designed to match the stage -storage -discharge from the
O.D.P. Detention Pond 212 is located west of Kansas Drive and north of Waukee Drive.
Table 5.2 summarizes the operating parameters for the proposed water quality ponds for
Rigden U. Appendix G provides the pond sizing calculations.
Table 5.2 Water Quality Pond Summary
MAJOR
BASIN
Trib.
area
(acres)
Impervious
Ratio, la
% Impervious
I = IaM00
WQCV
(watershed Inches)
Design
Volume, Vol.
(Be-ft)
WQ Pond 1
5.56
59
0.59
0.23
0.13
WO Pond 2
3.52
55
0.55
0.22
0.08
WO Pond 3
25.25
51
0.51
0.21
0.53
5.4 Detention Pond Outfall Analyses
Major outfall structures are proposed for the two on -site detention ponds. Detention Pond
216 in the northeast comer of the site will have an inverted. siphon outlet as specified in the
"Overall Drainage Report for the Rigden Farm O.D.P." Pond 216 has an temporary outlet
that will be utilized until the downstream conveyance facilities are constructed. Detention
Pond 269 in the southern portion of the site will have an 8' by 4' reinforced box culvert
outlet. Both ponds will have inlet boxes with water quality control plates and weirs sized to
control outflows. Trash racks have been designed for both inlet boxes.
Drainage and Erosion Control Report Page 19
Rigden Faun — Filing Six February 8, 2002
Inlenvest Consulting Group
1218 West Ash, Suite C
W incisor, Colorado RUNOFF COEFFICIENTS &'% IMPERVIOUS
LOCATION:
The Center at Rigden Farm
PROJECT NO:
1049-034-00
COMPUTATIONS BY:
JH
DATE:
12/20/2006
Recommended Runoff Coefficients from Table 3-3 of City of Fart Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt,
Concrete
Roofs
Grave
Lawns (flat <2%, heavy soil;
Runoff
coefficient
C
%
Impervious
0.95
100
0.95
96
0.95
90
0.50
40
0.20
0
SUBBASIN
DESIGNATION
TOTAL
AREA
(so.)
TOTAL
AREA
(sq.ft)
PAVED
AREA
(sq.ft)
CONCRETE
AREA
(sq.ft)
ROOF
AREA
(sq.ft)
GRAVEL
AREA
(sq.ft)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
(0)
%
Impervious
REMARKS
Al
1.24
54,031
32,563
5,715
9,323
0
6,430
0.86
86
A2
0.83
35,979
24,130
2,174
3,885
0
5,790
0.83
83
A3
0.84
36,568
26,092
5,085
1,561
0
3.830
0.87
89
A4
0.85
37,026
294
2,802
21,067
0
12,863
0.69
59
A5
0.14
8,147
0
1;106
4,875
0
166
0.93
89
A6
0.08
3,454
0
491
2,963
0
0
0.95
91
A7
0.10
4,456
0
609
3,161
1
686
0.83
77
Equations
- Calculated C coefficients & % Impervious are area weighted
C=£(Cl Ali /At
Ci = runoff coefficient for specific area, Al
At = areas of surface with runoff coefficient of Cl
n = number of different surfaces to consider
At = total area over which C Is applicable; the sum of all Ai's
8o v.As Cval
150:2
5.1
1.0
1
12.
152:5
78.2
3.5
0
37.
153:5
6.8
'1.4
4
32.
154:5
5.5
1.4
4
19.
156:5
57.7
1.8
0
44.
157:2
28.0
.1- 3.3:D
3
35.
159:2
8.4
.1 2.7:D
2
2.
162:3
82.6
(DI'RFT FLOW)
0
36.
163:4
09.8
1.0
0
51.
172:2
58.8
.1 6.6:D
1
16.
173:5
53.2
4.1
1
29.
178:4
37.0
4.1
0
51.
184:5
73.3
4.9
0
40.
185:1
84.6
2.0
2
30.
188:1
70.3
3.0
0
46.
193:2
73.3
.1 12.6:D
1
32.
194:1
22.8
7.1
0
55.
201:2
22.9
.1 1.1:D
0
44.
207:2
20.0
.1 9.70
2
14.
208:2
20..0
.1 9.5:D
2
6.
209:2
9.0
.1 S.S:D
2
15.
210:2
25.4
.1 1.2:D
0
50.
211:2
9.9
.1 3.1:D
2
3.
212:2
40.3
:1 .B:D
0
42.
213:2
44.2
'.1 11.4:D
2
1.
214:2
23.3
.1 11.5:D
2
10.
215:2
85.1
.1 33.2:D
2
19.
216:2
L08.3
.1 33.0:
217:2
19.7
.1 2.2:D
1
16.
218:2
L09.5
.1 1.6:D
0
39.
244:2
6.0
.8
2
18.
251:2
5.4
.1 AM
1
27.
257:1
63.1
3.7
3
33.
269:2
29.7
.1 4.4:D
0
47.
273:3
88.8
(DnWCT FLCW)
0
51.
288:3
22.9
(DIFZf>✓P FUN)
0
41.
303:2
5.6
..1 1.4:D
1
55.
306:2
35.2
.1 .2:D
0
36.
307:5
31.5
2.0
0
39.
313:2
1.7
.1 .6:D
1
37.
338:2
64.1
.1 5.6:D
1
16.
351:3
15.3
(D17= FLOW)
0
36.
361:4
315.3
1.0
0
36.
400:4
60.5
.6
0
40.
401:4
L32.5
.8
0
41.
410:2
2.8
.1 2.9:D
2
15.
413:2
1.5
.1 1.9:D
2
7.
444:3
127.1
(DIP= FLOW)
0
55.
466:3
617.2
(DIRECT FLDW)
0
40.
471:3
248.0
W= FUIW)
0
38.
500:3 1L18.2
(DIREC1' FIDW)
0
59.
544:3
6.0
(DIRECT FLCW)
2
14.
562:3
30.0
(DIRFl FLOW)
0
29.
600:4
327.0
1.3
0
36.
644:3
121.1
(D17iF= FLOW)
0
55.
662:3
152.6
(Dn= FLOW)
0
36.
849:3
14.2
(D= FLOW)
0
16..
916:3
P28.3
(DnU= FLOW)
0
41.
Rigden Farm- Alternate Outlet -100 YR SWMM output
File: Alt-100.out, 12/05/01
Page 12 of 12
582
NORTH IMB.
STORM sEvAm
V
=777 ----------- 18 4
M�
. ..... ....
581
- - -----------
A f
.224
49'25
ot
4924 'V
T I
POND 2
V"
492-7 'X.
584
if 19.7
PV 583
ko
,v
I.
LOCATED GENERALLY IN THE NORTH HALF OF THE SOUTHEAST
R OF SECTION 29, TOWNSHIP 7 NORTH, RANGE 68 WEST OF
INCIPAL MERIDIAN, IN T)qE CITY OF FORT COLLINS., LARIMEF,
)RADO.
Nu I
'.N
N
J)I
A
f/
k
----------
_CULVERT CROSS
a'
IV
A91
TE AREA IS 308.33 ACRES, INCLUOINO ko.w. ANP, rArr)"irl.
1
d
APPENDIX B
Drainage and Erosion Control Plan
and Hydrologic Computations
_-4"
_
dP
I'I i SF
ton SF
1 I
LOT a
rl ,
IIr'E f r.85 .69
a1aVOL4ORNE
aP 2
LOT 41-,-T---- --'
E IOr a
Iona q i
ice' I I tare
••I -Iona
I
---------i--l----------
Im 3 I tar
N*
Ian 10T- ' ' {OT 17
�l II
AOWA DR/rE_+a A
T----�---- ---- ;---------- _-------- -10
\ t I I
\ ,I I. I li Iliiili�.11llli I I
II I I
\\ 1' 1 I I III III njllj�l I I
\ I ice � II i!I II�I ulllli II � � it
DRAINAGE SUMMARY TABLE
DESIGN
POINT
AREA
DESI0.
AREA
ACRES
C 10
C 100
TO 10
MIN
TO 100
MIN)
O 10
(CFS)
0 100
(CFS
1
Al
1.24
0.86
1.00
SO
&0
. 6.5
12.3
2
A2
0.a3
O a3
1.00
&3
SO
4.2
&2
3
A3
0.84
0.87
1.00
&0
&0
4.5
&3
A4
0.a5
0.69
Ow
7.0
&1
3.3
7.2
A5
0.14
0.93
1.00
&0
SO
0.8
1.4
AB
0.08
0.95
1.00
S0
SO
0.5
0.8
A7
0.10
0.83
1.00
&a
SO
0.5
0.1
-'L T L----------
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CONSTRUCTION SEQUENCE
Mahn M 011R AL I.®1 IMY 0A2 m/1]/Qr
e"'-Md.Ils�s d: •ate www r +... w.� r. w r r.asrF.•..a
0 50
100
50
25
SCALE: 1"= 50'
NOTES:
LEGEND
We . fee'.. We PR POSED ORNNAGE 60.5w MME LINE
GRAenoce
unam
_W MINORSTOM NM1f,
NwoasroRa RunoFF mFFFIC1ENr
�w/fig DRNNAGE IpAsw AraA
D GNpciw
PROPOSED WeZ=0N OF DYER 0FLOW
® VENIOLETMOe'IG CONfROLPb
® SIT'll
® ORANGE CON41aVQfOn FENCE
® � CUf�INLETOPAVEL FRIER
® O cancRE AGHau ATan
< ® MClPINLETWAT lfFILTER
1. ANY LOT/AREA NOT IMMEDIATELY BUILT ON SHALL BE SEEDED AND MULCHED. WHEN THE OVERALL CONSTRUCTION IN AN AREA IS
FINISHED, IT WILL BE VEGETATED PER THE APPROVED LANDSCAPE PLAN.
2. SEE LANDSCAPE PLAN FOR PLANTINGS THROUGHOUTTHE SITE.
STANDARD ERoGION AND SEDSOO T CONTROL caRSTRucmop R.W NOTES
Seplernbr, 2003
mudw con" I agpwtr must be notified at Irnt tomty-foul (xq hwn prior to my can.wcum on Nh alto.
(2) Tha. Ma be no edrth-dlsWNMg mHdly .tddo Me 14nits deeimat" . the accepted plan&
(M) All noun" po&neter at and a-atuctl. fencing Mail be Install" prior to my land disturbing mlfulty (stoclmGhy sapping,
gradlnA etc} Ad other raauned Taal. caned .moss Nail be Installed at Me aWom.t. tm. In M. construction sodium. m
Indcal" In Me approved p n)oct • nedule. con.wcti. plan, and roei. con" report
(A.) At a tnnm during cmanuctlm, the 0srlapr ma be respmaWle for orormting and controlling on -alto rcd.n IndudIng keeping
the property suMal.dy wtred se . to minMim .Intl dam sedknrnt. Tha DMapor Ma alp be napmebe. fr InstaIng anti
maintaining ON tool. can" focA[Uss Nam Main. .
(i) Ae-daWrbm. oegetatlon dual be protect" and retained mwe pm®I& Rmanal or daturbance of eslalMg ..tall. Mall
be Omit" to the roo(s) nIamet for knmediate construction opratlma and for Me Nortest mecdcal prod of u ne.
(&) All sofa cgestl doing land dais g cWty (ab'bpIn% 7S uWty Installations, steckpling, MInq, etc) Ma be kept In a
rough." randUm by riphg Or dining d.g land cant.n mK .dab, wg.tution, or other pe nnuanent rcdo .nnal UP, an
Installed. No sops In aem outs" project street righta-al-.ay Nail rrnab rmmed by land dispiriting activity for more than MYty
(30) dap More reauaad lemprry or prmmmt raNn can" (&4 red/mum. Imdc lnq atc) is kiddld uni® atte
apprm d by Me aty/Canty.
(T.) In order to mIninise .rani. putmUd, of tanparmy (structural) rpdm can" memuro Mdb
(&) 8. Inepecedl a a mNhnum of .. awry 1. (2) e.eiu m4 aftr edM tlmlficant .ern wont and repaired or n.nswcted m
nacemry In adr to mean the continued per ufnc* of Mob Intended hrnetlm.
(b.) Ranain in place anti win Kea m all Ma •arcndNg disturbed Teas re wffidmUy a M" as detrrnNed by fine rani.
con" incector.
(c.) Be ranowd aftr the die has been .umcimtiy otabpimd ae "t•nIn" by Me salon can" Inspector.
IWhen ton rodan eon" mcsuro an remonad Me D.wl r Mdl ( ) porary ep be repandNa im Me clr up antl mmowl of all
sedbnmt and dMHs hen a dralnaga Inhaawetun and Stir public facNtl.o.
(9.) The contractor Mall Immedktay dean up my construction matmal. Inadwrtmtly deported ..dating .O.Wt% edwealke, or athr
publi. right. of Way and male sure streets and wdke.A . cleaned at M. and of aoM erxing day
(10.) All retain" aadl.mt% paMmkoly Mode an pawl neadcy, audoces, Mat be r•nowd and disposed of,in a manner and location
c a. not to cause Mak rated. Into any ratan of Me United State&
(11.) No soil atodpta Mall exceed tm (10) feet In height M sot Nockpgm Mail be pntct" ham .Wlmwt tranepart by suiface
rcghming, watering and perm.tr aIlt fencing. My sop Madppa rarnaIning aftr Mlrty (b) dop Nall be wooded and mulchd
(12) Tha st.wartr whims capacity of detention panda WI ba rotor" and slam .sew In. Wil be dean" upon ..plod. of Me
woJsct and bMan Kmisg Me .Sint.... oar to Ma Sty/Cmnly or Hamer me Auo.Iatim (HOA).
(13.) aty OdFinae and Colorado Die rge Pa nit Splrn (COPS) reauLsnmtd mat. It unlawful to Womarg. or allow the disompe of
any pollutant or contanlnated water non can ov.U. sit.& Pollutants include. but are not IMited to discrded bulldlrg matMaiy
eona.te wd saM.l. alarmed& a and goo product& Illtr, and ednitry oases. The developer Mail at all tbno taut Mataw
mmurse are nacaory to amount Me proper containmmt and dhpmd of pallutmts an one sits In acardmof oath my and all
applicable local. state. and fadral ragaiatian&
(14,) A designated ran Na be prodded on site la, cmoret. wd Nuts ~.L The area Mail be consw.ted c at to contain
eaM.t material and looted at local fifty (W) feet away noon any sate during .nsw.tim. Upon completion of canatmcd.
aetlrltim no emanate WeN.L material WO be removed and VOWY dfaposed of pNor to the rWo being rolyd
(11) To ounce Mal sod i ant doai not mow aN of IndMdual late an* a man of th. fdlceIng sodinmt/ermim can" SNP. Mall be
Installed and mantan" mK the late rW ouf centy ntabplmd m d.tWnnb" by the radon con" Inep«tor. (Wain losdand Sty
Limits Only). -
(o.) Betio a gutty domepout&
(bon) Out to drainage sede&
(c.) Along lot pelmet..
(d) OMr Iaratane. If naodod
(ti) Conduces In the field may errant rodct can" mealem In addition to Mat is Nam an Man plan& Th. Do edoper Na
inplrnmt whore r moce ro an debmnned nee.oa y m dneded by the Sly/County
CITY OF FORT COWNS, COLORADO
UTILITY PLAN APPROVAL
CALL UTILITY NOTIFICATIDN
CENTER OF COLORADO
1-800-922.1987
APPROVED: STY INaNM -
CALL t-ItiS0E= DAYS IN "VANCE
CHECKED BY:
SET13IE YOU BIG, MADE, cal DCAVATE
_
WARR a WASYEWAIER UTUIY
FOR THE MINCING BF OIDERRpDtiND
14DM 0BXGM
CHECKED BY:
_
sraRUWA UALTY
PRELIMINARY PLAN )
CHECKED BY: _
PARNs d RELREAnON
CHECKED BY: _
TRAmc ENrrlmt
NOT FOR CONSTRUCTION
CHECKED BY: _
Z
PROD. NO.
IIOF16
Intemest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION: The Center at Rigden Farm
PROJECT NO: 1049-034-00
COMPUTATIONS BY: JH
DATE: 12/20/2006
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)
Concrete
Roofs
Gravel
Lawns (flat <2%, heavy soil)
Runoff
coefficient
C
%
Impervious
0.95
100
0.95
96
0.95
90
0.50
40
0.20
0
SUBBASIN
DESIGNATION
TOTAL
AREA
(ac.)
TOTAL
AREA
(sq.ft)
PAVED.
AREA
(sq.ft)
CONCRETE
AREA
(sq.ft)
ROOF
AREA
(sq.ft)
GRAVEL
AREA
(sq.ft)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
(C)
%
Impervious
REMARKS
Al
1.24
54,031
32,563
5,715
9,323
0
6,430
0.86
86
A2
0.83
35,979
24,130
2,174
3,885
0
5,790
0.83
83
A3
0.84
36,568
26,092
5,085
1,561
0
3,830
0.87
89
A4
0.85
37,026
294
2,802
21,067
0
12,863
0.69
59
A5
0.14
6,147
0
1,106
4,875
0
166
0.93
89
A6
0.08
3,454
0
491
2,963
0
0
0.95
91
A7
0.10
4,456
0
609
3,161
0
686
0.83
77
83,079
17,982
46,835
Equations
- Calculated C coefficients & % Impervious are area weighted
C=£(CiAi) /At
Cl = runoff coefficient for specific area, Ai
Ai = areas of surface With runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
flow.>ds _ Cval
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APPENDIX C
Inlet Sizing and
StormCAD Output Data
Rectangular Area Inlet Capacity
NEENAH R-3406
LOCATION: The Center and Rigden Farm
PROJECT NO:
COMPUTATIONS BY: MPO
SUBMITTED BY: Interwest Consulting Group
DATE: 3/13/2007
Inlet Data: Weir Length 25.7 ft
Open Area 5.5 ft^2
Solve for h using Orifice Equation
Q = CA sgrt(2gh)
where Qo = flow through orifice (cfs)
Co = orifice discharge coefficient
g = gravitational acceleration = 32.2 ft/s
Ao = effective area of the orifice (f Z)
h = head on the orifice (ft)
Qo = 12.30 cfs
Ao = 2.75 ftz (Assume 50% clogged)
Co = 0.65
Solve for h: 0.74 ft
Solve for h using Weir Equation
Q = CLH'
where C = weir coefficient
H = overflow height
L = length of the weir
Q = 12.30 cfs
C = 3.00
L = 25.7 ft
Solve for H: 0.29 ft
ORIFICE CONTROLS Q= 12.30 cfs
Required Head d= 0.74 ft
Available Head Prior to Overtopping 0.50 ft OK
Rectangular Area Inlet Capacity
NEENAH R-3406
LOCATION:
The Center and Rigden Farm
PROJECT NO:
COMPUTATIONS BY:
MPO
SUBMITTED BY:
Interwest Consulting Group
DATE:
3/13/2007
Inlet Data: Weir Length
15.9 ft
Open Area
3.7 ft^2
Solve for h using Orifice Equation
Q = Ck. sgrt(2gh)
where % = flow through orifice (cfs)
Co = orifice discharge coefficient
g = gravitational acceleration = 32.2 ft/s
A. = effective area of the orifice (ft)
h = head on the orifice (ft)
Qo = 8.20 cfs
Aa = 1.85 ftZ (Assume 50% clogged)
Co = 0.65
Solve for h: 0.72 ft
Solve for h using Weir Equation
Q = CLH"
where C = weir coefficient
H = overflow height
L = length of the weir
Q = 8.20 cfs
C = 3.00
L = 15.9 ft
Solve for H: 0.31 ft
ORIFICE CONTROLS Q= 8.20 cfs
Required Head d= 0.72 ft
Available Head Prior to Overtopping 0.50 ft OK
LOCATION:
PROJECT NO:
COMPUTATIONS BY
SUBMITTED BY:
DATE:
Inlet Data: Weir Length
Open Area
Rectangular Area Inlet Capacity
NEENAH R-3406
The Center and Rigden Farm
MPO
Interwest Consulting Group
3/13/2007
Solve for h using Orifice Equation
15.9 ft
3.7 ft^2
Q = C� sgrt(2gh)
where %= flow through orifice (cfs)
Co = orifice discharge coefficient
g = gravitational acceleration = 32.2 ft/s
k = effective area of the orifice (ft)
h = head on the orifice (ft)
Qo = 8.30 cfs
A. = 1.85 ftZ (Assume 50% clogged)
Co = 0.65
Solve for h: 0.74 ft
Solve for h using Weir Equation
Q = CLH'
where C = weir coefficient
H = overflow height
i L = length of the weir
Q = 8.30 cfs
C = 3.00
L = 15.9 ft
Solve for H: 0.31 ft
ORIFICE CONTROLS Q= 8.30 cfs
Required Head d= 0.74 ft
Available Head Prior to Overtopping 0.50 ft OK
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APPENDIX D
Erosion Control Calculations
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' Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
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EFFECTIVENESS CALCULATIONS DURING CONGTRUM0N
PROJECT: THE CENTER AT RIGDEN STANDARD FORM B
COMPLETED BY: JH DATE: 12-Mar-07
EROSION CONTROL
C-FACTOR
P-FACTOR
METHOD
VALUE
VALUE
COMMENT
BARE SOIL
1.00
1.00
SMOOTH CONDITION
ROUGHENED GROUND
1.00
0.90
SEDIMENT BASIN
1.00
0.50
ROADS/WALKS
0.01
1.00
GRAVEL FILTERS
1.00
i 0.80
PLACED AT INLETS
SILT FENCE
1.00
0.50
STRAW MULCH
—S 0.06
1.00
ESTABLISHED GRASS
0.08
1.00
STRAW BARRIERS
1.00
0.80
EFF = (I-C'P)• 100
MAJOR
SUB
BASIN AREA
EROSION CONTROL METHODS
BASIN
BASIN
(Ac)
AI+R2tA3
2•411
C= (4,08hc)(O-DO
A4 hA5+Ala+
Al
11
(4.D8 Ac)
= 0.Ota
P- (2•q Ac)(0`4 0 ���)�0.5�
Toi 4. 08
lob
= 95.7°��
TOTAL AREA =
TOTAL EFF =
' REQUIRED PS =
Erosion Rigden.xls 1 of 1
rInterwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
' EFFECTIVENESS CALCULATIONS POST C 0NSTRUeTl0W
PROJECT: THE CENTER AT RIGDEN STANDARD FORM B
COMPLETED BY: JH DATE: 12-Mar-07
EROSION CONTROL
C-FACTOR
P-FACTOR
METHOD
VALUE
VALUE
COMMENT
BARE SOIL
1.00
1.00
SMOOTH CONDITION
ROUGHENED GROUND
1.00
0.90
SEDIMENT BASIN
1.00
♦ 0.50
ROADS/WALKS
♦ 0.01
1.00
GRAVEL FILTERS
1.00
0.80
PLACED AT INLETS
SILT FENCE
1.00
0.50
STRAW MULCH
0.06
1.00
ESTABLISHED GRASS
♦ 0.08
1.00
STRAW BARRIERS
1.00
0.80
EFF = (I-C-P)-100
MAJOR
SUB
BASIN AREA
EROSION CONTROL METHODS
BASIN
BASIN
(Ac)
Al i AZi A3 t
RwA,51NAlks Roof s
3.40
C= (3.4oRc.) (D.o li f Co•U$Ac) C0.08�
A4tft5 tAIP t
�,
LArldlscape.
0•�P�
4.DE5Av
��,0.02
P= (3.40AC) Co.5)-� (D-Wb l-O 5) _
(4•D8 hC.-)
P_ 0.5
[I - Co.DO
TOTAL AREA =
TOTAL EFF =
' REQUIRED PS =
' Erosion Rigden.xls 1 of 1
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1
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CONSTRUCTION S
THE CENTER AT RIGDEN FARM DATE: 03/13/07
Indicate by use of a bar line when construction will occur and when BMP'3 will be Installed/removed
in relation to the CONSTRUCTION phase.
CONSTRUCTIONPROJECT.
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GRADING (INCLUDES OVERLOT)
- r
------_--_--
7 ..
------------
-_----------
CONCRETE INSTALLATION (INCLUDES OFFSITE)
POND OUTLET STRUCTURES
BOX CULVERTS I BRIDGES
• M 1
24
1
Cost Est
EROSION CONTROL COST ESTIMATE
Project: THE CENTER AT RIGDEN
Prepared by: JH
ITEM
IQUANTITY
JUNIT
COST/UNIT
TOTAL COST
Silt Fence
1438
LF
$3
$4,314
Straw Bale Barrier
0
EA
$150
$0
Inlet Protection
11
EA
$150
$1,650
Construction Entrance
1
EA
$550
$550
Subtotal
Contingency (50%)
Total
$6,514
$3,257
$9,771
CITY RESEEDING COST
Reseed/Mulch
4.08
ACRE
$775
$3,162
Subtotal
Contingency (50%)
Total
$3,162
$1,581
$4,743
EROSION CONTROL ESCROW AMOUNT $9,771
Page 1