HomeMy WebLinkAboutMORNINGSTAR ASSISTED LIVING & MEMORY CARE - PDP - PDP130024 - REPORTS - DRAINAGE REPORTPRELIMINARY DRAINAGE REPORT
MVG-MORNINGSTAR
ASSISTED & MEMORY CARE PROJECT
Prepared for:
Max Consulting, LLC
4061 S. Clermont St.
Englewood, CO 80113
(303) 482-7420
Prepared by:
Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado 80550
(970) 674-8488
October 1, 2013
Job Number 1173-105-00
ii
October 1, 2013
Mr. Wes Lamarque
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Preliminary Drainage Report for MVG-Morningstar Assisted & Memory Care
Project
Dear Wes,
I am pleased to submit for your review and approval, this Preliminary Drainage Report for the
MVG-Morningstar Assisted & Memory Care Project development. I certify that this report for
the drainage design was prepared in accordance with the criteria in the City of Fort Collins Storm
Drainage Manual.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
Sincerely, Reviewed By:
Mark Morrison, E.I.T. Robert Almirall, P.E.
Colorado Professional
Engineer No. 33441
iii
TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................................................ iii
1. GENERAL LOCATION AND DESCRIPTION ................................................................ 1
1.1 Location ........................................................................................................................... 1
1.2 Description of Property ................................................................................................. 1
2. DRAINAGE BASINS AND SUB-BASINS .......................................................................... 1
2.1 Major Basin Description ................................................................................................ 1
2.2 Sub-basin Description .................................................................................................... 2
3. DRAINAGE DESIGN CRITERIA ...................................................................................... 2
3.1 Regulations ...................................................................................................................... 2
3.2 Development Criteria Reference and Constraints ...................................................... 2
3.3 Hydrological Criteria ..................................................................................................... 3
3.4 Hydraulic Criteria .......................................................................................................... 3
3.5 Floodplain Regulations Compliance ............................................................................. 3
4. DRAINAGE FACILITY DESIGN ....................................................................................... 4
4.1 General Concept ............................................................................................................. 4
4.2 Specific Flow Routing .................................................................................................... 5
4.3 Drainage Summary ........................................................................................................ 6
5. CONCLUSIONS .................................................................................................................... 6
5.1 Compliance with Standards .......................................................................................... 6
5.2 Drainage Concept ........................................................................................................... 7
6. REFERENCES ...................................................................................................................... 7
APPENDIX
VICINITY MAP AND DRAINAGE PLAN .............................................................................. A
HYDROLOGIC COMPUTATIONS .......................................................................................... B
1
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location
The MVG-Morningstar Assisted & Memory Care Project development is located in
southeast Fort Collins. It is located in the Southwest Quarter of Section 30, Township 6
North, Range 68 West of the Sixth Principal Meridian, in the City of Fort Collins,
Larimer County, Colorado. See the location map in Appendix A.
The project is located west of Lochwood Drive, north of E. Horsetooth Road, and
bounded on the west and north sides by existing residential lots. An existing drainage
ditch with an existing 25 ft Drainage Easement runs along the west edge of the property,
dividing it from the residential properties.
1.2 Description of Property
The property consists of approximately 4.42 acres of land. The existing land currently
drains from southeast to northwest at approximately a 2% grade. The land is currently
vacant with mild sloping terrain and covered with natural dry-land vegetation across the
entire site. The only offsite flow entering the site is through an existing concrete drainage
ditch originating at the SW corner of the property and conveys runoff to the northeast.
There is an existing 25’ drainage easement accompanying the existing concrete ditch,
extending from the existing flowline 25’ to the west. An additional 25’ drainage
easement is proposed, extending from the flowline 25’ to the east, to make the entire
Drainage Easement 50’ wide up to the Tract A-Utility & Drainage Easement. The
channel is not mapped by FEMA. The project is located in FEMA FIRM Panel
08069C1000F, Zone X.
2. DRAINAGE BASINS AND SUB-BASINS
2.1 Major Basin Description
The proposed development lies within the McClelland’s Creek Master Drainage Basin.
The entire site currently drains to an existing concrete drainage ditch along the west and
northwest property boundary. James H. Stewart and Associates performed a drainage
study on this drainage in March of 1978 and determined the 100-year storm to produce
217.0 cfs. However, the updated 2010 SWMM model for the basin shows a 2-year storm
2
run-off of 20.6 cfs and a 100-year storm run-off of 150.2 cfs. See Appendix B for
existing site hydrologic computations.
2.2 Sub-basin Description
The existing site has a historic runoff of 1.5 cfs and 6.7 cfs for the 2-year & 100-year run-
off event, respectively, with a historic 2-year release rate of 0.35 cfs/acre. The site will be
divided into 2 sub-basins for proposed construction activities. Sub-basin A will consist
of approximately 1.24 ac and will be collected in a small extended detention basin located
southwest of the proposed building before releasing into the existing drainage ditch to the
west. Sub-basin B consists of approximately 3.18 ac and drains to the northwest corner
of the property where it will be collected in a second extended detention basin before
releasing into the existing concrete drainage ditch bounding the property. Once the run-
off enters the existing ditch, it will flow northeast eventually reaching McClelland’s
Channel.
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations
This report was prepared to meet or exceed the “City of Fort Collins Storm Drainage
Design Criteria Manual” specifications. Where applicable, the criteria established in the
“Urban Storm Drainage Criteria Manual” (UDFCD), developed by the Denver Regional
Council of Governments, has been used.
3.2 Development Criteria Reference and Constraints
Urban Drainage and Flood Control District (UDFCD) recommends a Four Step Process
for receiving water protection that focuses on reducing runoff volumes, treating the water
quality capture volume (WQCV), stabilizing drainageways and implementing long-term
source controls. The Four Step Process applies to the management of smaller, frequently
occurring events.
Step 1: Employ Runoff Reduction Practices
To reduce runoff peaks, volumes, and pollutant loads from urbanizing areas, implement
Low Impact Development (LID) strategies, including Minimizing Directly Connected
3
Impervious Areas (MDCIA). See the LID Area Exhibit in Appendix B.
Runoff for the site will be split around the proposed building’s SE corner to the west and
north, respectively.
Sub-Basin A
Runoff directed to the west will be routed through a vegetated, landscaped water way to
an extended detention basin, herein referred to as “Water Quality Pond A” equipped with
a Water Quality Outlet Structure which will release flow into the existing concrete
drainage ditch along the west edge of the property. Water Quality Pond A will also be
constructed with Gravel Dry Wells along the flow line of the basin to help slow the
basin’s time of concentration.
Sub-Basin B
Runoff directed to the north will be routed through vegetated areas, a rain garden, and a
storm drain system thereby reducing runoff from impervious surfaces over permeable
areas to slow runoff and increase the time of concentration and promote infiltration.
Runoff from the parking lot shall drain across Pervious Pavers before entering a second
extended detention basin, herein referred to as “Water Quality Pond B”.
Step 2: Implement BMPs that Provide a Water Quality Capture Volume with Slow
Release
Sub-Basin A
Water Quality Pond A utilizes a landscaped drainage way as well as equipping the
Extended Detention Basin with a Water Quality Outlet Structure designed to allow
sediments to settle while releasing treated flows at or less than historic rates.
Sub-Basin B
A Proposed Rain Garden located SE of the main entrance shall collect a majority of the
down-spout runoff before conveying the water to the second water quality treatment
pond. Pervious Pavers are located within Sub-basin B, placed close to the proposed
Extended Detention Basin to help reduce total runoff by allow water to infiltrate. Water
Quality Pond B also shall be equipped with a Water Quality Outlet Structure designed to
allow sediments to settle while releasing treated flows at or less than historic rates.
Step 3: Stabilize Drainageways
Natural Drainageways are subject to bed and bank erosion due to increases in frequency,
duration, rate and volume of runoff during and following development. Rip-Rap shall
4
be used at the outlet of both Water Quality Pond’s as well as the two points where a
majority of water will enter Water Quality Pond B. The Rip Rap shall be stabilized in
place.
Step 4: Implement Site Specific and Other Source Control BMPs
Proactively controlling pollutants at their source by preventing pollution rather than
removing contaminants once they have entered the stormwater system or receiving waters
is important when protecting storm systems and receiving waters. This can be
accomplished through site specific needs such as construction site runoff control, post-
construction runoff control and pollution prevention / good housekeeping. It will be the
responsibility of the contractor to develop a procedural best management practice for the
site.
3.3 Hydrologic Criteria
Runoff computations were prepared for the 2-year and 10-year minor and 100-year major
storm frequency utilizing the rational method. The Modified FAA method was used to
determine preliminary detention volumes for the proposed water quality ponds.
All hydrologic calculations associated with the basins are included in Appendix B of this
report.
Final water quality volumes will be presented in the final drainage report and calculated
using the method recommended in the “Urban Storm Drainage Criteria Manual”.
3.4 Hydraulic Criteria
All hydraulic calculations will be presented in the final drainage report and prepared in
accordance with the City of Fort Collins Drainage Criteria.
3.5 Floodplain Regulations Compliance
No work is proposed within the existing floodplain.
4. DRAINAGE FACILITY DESIGN
5
4.1 General Concept
The proposed MVG-Morningstar site was designed to treat run-off as close to the point-
source as possible, while also minimizing the length of drainage routing to the most
feasible extents of the site.
The proposed site shall be divided into two sub-basins based on design points A and B.
The proposed drainage design follows the existing drainage pattern of southeast to
northwest. The project will consist of an Assisted & Memory Care Complex building
with a footprint of approximately 42,500 SF, a parking area for patients and employees,
an access lane, a retaining wall, sidewalks and landscaped areas. All proposed site run-
off is directed to a water quality pond at one of the two design points before being
released off-site. Each water quality pond shall be equipped with a Water Quality Outlet
Structure, designed specifically for that sub-basin, to treat and release the run-off into the
existing concrete ditch at or below historic run-off rates.
Both of the extended detention ponds serving as water quality ponds shall also act as on-
site detention ponds for the proposed construction. The on-site detention shall hold the
proposed 100-year run-off and release it at the historic 2-year storm release rate.
4.2 Specific Flow Routing
A summary of the drainage patterns within each basin is provided in the following
paragraphs.
Sub-Basin A includes the southwest corner of the property, excluding the existing
drainage ditch, and the south half of the downspouts from the proposed building,
approximately 1.24 ac. From the downspouts, flow will be routed through vegetated
areas carrying flow away from the building or sheet flow over-top the sidewalk. A
sidewalk chase is proposed in one location to keep positive drainage through the
sidewalk. Remaining Sub-basin A flow will be collected and routed through a concrete
pan along the south edge of the property to Water Quality Pond A, which is located just
southwest of the proposed building. Once the run-off is treated, the outlet structure
discharges into the existing concrete channel to the west of the site, eventually reaching
McClelland’s Channel. Sub-Basin A is calculated to have a 10-year and 100-year
discharge of 1.7 & 4.5 cfs, respectively.
6
Sub-Basin B includes the remaining approximately 3.18 acres located northeast of Sub-
basin A within the site, including the north half of the proposed building downspouts.
The east side building down-spout run-off as well as that immediately adjacent to the
southeast side of the proposed building will be collected in a proposed rain garden before
entering the site’s storm drain system. The north side building down-spout run-off as
well as that immediately adjacent to the north, northeast, and northwest sides of the
building shall sheet flow to the northwest to the proposed Water Quality Pond B. Parking
and access road run-off will also sheet flow to the northwest or enter the site’s storm
drain system, which also drains into Water Quality Pond B. Run-off is then treated and
released into the existing drainage ditch flowing northeast into McClelland’s Channel.
Sub-basin B is calculated to have a 10-year and 100-year discharge of 4.8 & 12.3 cfs,
respectively.
4.3 Drainage Summary
The percent impervious weighted average of the entire site is 48.6%. All proposed site
runoff follows existing drainage flow patterns while adding a level of water quality to the
discharge.
Drainage facilities located outside of the right of way (including the rain garden, water
quality pond, proposed storm sewer system and the pond outlets) will be maintained by
the owners of the property. The property owner shall also share maintenance of the 50’
Drainage Easement and existing drainage ditch to the west of the property with the
Collindale PUD Homeowners Association.
5. CONCLUSIONS
5.1 Compliance with Standards
All computations that have been completed within this report are in compliance with the
City of Fort Collins(COFC) Erosion Control Reference Manual for Construction Sites,
the COFC Storm water Criteria Manual, the COFC Master Drainage Plans, and the
COFC floodplain regulations. All floodway information is in compliance with Chapter
10 of the City of Fort Collins Municipal Code and all State and Federal regulations.
7
5.2 Drainage Concept
The proposed drainage concepts presented in this report and on the construction plans
adequately provide for stormwater quantity and quality treatment of proposed impervious
areas. Conveyance elements have been designed to pass required flows and to minimize
future maintenance.
If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit will be required.
6. REFERENCES
1. City of Fort Collins, “Storm Drainage Criteria Manual”, (SDCM), dated March,
1986.
2. Urban Drainage and Flood Control District, “Urban Storm Drainage Criteria
Manual”, Volumes 1 and 2, dated June 2001, and Volume 3 dated September
1999.
3. ICON Engineering, Inc., “McClelland’s Creek Master Drainage Plan Update”,
dated November 20, 2000 (Revised March 2003).
A
APPENDIX A
VICINITY MAP AND DRAINAGE PLAN
B
APPENDIX B
HYDROLOGIC COMPUTATIONS
✁
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✕ ✢ ✓ ✜ ✔ ✔ ✔ ✓ ✓ ✓ ✓ ✓ ✓
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❤ ⑩ ❶ ✐ ❷ ❸ ❹ ❺ ❦ ❻ ❼ ❽ ③ ◗ ❛ t ❯ ❴ ❯ ❬ ❯ t ◗ ❵ ◗ ❬ ❛ ❯ ❵ ❬ ◗ ❚ ❯ ❬ ❭ ✉
SUMMARY
Design Tributary Area C (2) C (10) C (100) tc (2) tc (10) tc (100) Q(2)tot Q(10)tot Q(100)tot
Sub-basin
Point (ac) (min) (min) (min) (cfs) (cfs) (cfs)
A (SW) A (SW) 1.24 0.39 0.39 0.49 12.0 12.0 11.4 1.0 1.7 4.5
B (NW) B (NW) 3.18 0.46 0.46 0.58 14.1 14.1 14.1 2.8 4.8 12.3
DRAINAGE SUMMARY TABLE
Page 1
TOTAL SITE AREA: 4.42 acre
NEW IMPERVIOUS AREA: 2.15 acre
MINIMUM AREA TO BE TREATED: 1.08 acre
AREA 1 - GRASS SWALE: 0.27 acre
AREA 2 - RAIN GARDEN: 0.50 acre
AREA 3 - GRAVEL DRY WELLS: 0.54 acre
AREA 4 - PERVIOUS PAVERS 0.47 acre
TOTAL AREA TREATED: 1.78 acre
LID AREA EXHIBIT
Sheet 1 of 3
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
Ia
= 38.00 %
A) Tributary Area's Imperviousness Ratio (i = Ia
/ 100 ) i = 0.38
B) Contributing Watershed Area (Area) Area = 1.240 acres
C) Water Quality Capture Volume (WQCV) WQCV = 0.17 watershed inches
(WQCV =1.0 * (0.91 * I
3
- 1.19 * I
2
+ 0.78 * I))
D) Design Volume: Vol = (WQCV / 12) * Area * 1.2 Vol = 0.0216 acre-feet
2. Outlet Works
A) Outlet Type (Check One) X Orifice Plate
Perforated Riser Pipe
Other:
B) Depth at Outlet Above Lowest Perforation (H) H = 2.00 feet
C) Recommended Maximum Outlet Area per Row, (Ao
) Ao
= 0.1 square inches
D) Perforation Dimensions:
i) Circular Perforation Diameter or D = 0.500 inches
ii) Width of 2" High Rectangular Perforations W = inches
E) Number of Columns (nc, See Table 6a-1 For Maximum) nc = 1 number
F) Actual Design Outlet Area per Row (Ao
) Ao
= 0.2 square inches
G) Number of Rows (nr) nr = 6 number
H) Total Outlet Area (Aot
) Aot
= 1.2 square inches
3. Trash Rack
A) Needed Open Area: At
= 0.5 * (Figure 7 Value) * Aot
At
= 43 square inches
B) Type of Outlet Opening (Check One) X < 2" Diameter Round
2" High Rectangular
Other:
C) For 2", or Smaller, Round Opening (Ref.: Figure 6a):
i) Width of Trash Rack and Concrete Opening (Wconc
)
from Table 6a-1 Wconc
= 3 inches
ii) Height of Trash Rack Screen (HTR
) HTR
= 54 inches
Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility
MM
Interwest Consulting Group
October 1, 2013
MVG - Morningstar Facility
DETENTION BASIN A (SW)
Sheet 2 of 3
Designer:
Company:
Date:
Project:
Location:
iii) Type of Screen (Based on Depth H), Describe if "Other" S.S. #93 VEE Wire (US Filter)
Other:
iv) Screen Opening Slot Dimension, Describe if "Other" 0.139" (US Filter)
Other:
v) Spacing of Support Rod (O.C.) inches
Type and Size of Support Rod (Ref.: Table 6a-2)
vi) Type and Size of Holding Frame (Ref.: Table 6a-2)
D) For 2" High Rectangular Opening (Refer to Figure 6b):
I) Width of Rectangular Opening (W) W = inches
ii) Width of Perforated Plate Opening (Wconc
= W + 12") Wconc
= inches
iii) Width of Trashrack Opening (Wopening
) from Table 6b-1 Wopening
= inches
iv) Height of Trash Rack Screen (HTR
) HTR
= inches
v) Type of Screen (based on depth H) (Describe if "Other") Klemp
TM
KPP Series Aluminum
Other:
vi) Cross-bar Spacing (Based on Table 6b-1, Klemp
TM
KPP inches
Grating). Describe if "Other" Other:
vii) Minimum Bearing Bar Size (Klemp
TM
Series, Table 6b-2)
(Based on depth of WQCV surcharge)
4. Detention Basin length to width ratio (L/W)
5 Pre-sedimentation Forebay Basin - Enter design values
A) Volume (3% to 5% of Design Volume from 1D) acre-feet
(3% - 5% of Design Volume (0.0006 - 0.0011 acre-feet.)
B) Surface Area acres
C) Connector Pipe Diameter inches
(Size to drain this volume in 5-minutes under inlet control)
D) Paved/Hard Bottom and Sides yes/no
Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility
MM
Interwest Consulting Group
October 1, 2013
MVG - Morningstar Facility
DETENTION BASIN A (SW)
UD-BMP_v2.06.xls, EDB - SW POND 10/1/2013, 7:37 AM
Sheet 3 of 3
Designer:
Company:
Date:
Project:
Location:
6. Two-Stage Design - See Figure EDB-1
A) Top Stage (Depth DWQ
= 2' Minimum) DWQ
= feet
Top Stage Storage: no less than 99.5% of Design Volume (0.0215 acre-feet.) Storage= acre-feet
B) Bottom Stage Depth (DBS
= 0.33' Minimum Below Trickle Channel Invert) DBS
= feet
Bottom Stage Storage: no less than 0.5% of Design Volume (0.0001 acre-feet.) Storage= acre-feet
Storage = A * Depth Above WS To Bottom Of Top Stage Surf. Area= acres
C) Micro Pool (Minimum Depth = the Larger of Depth= feet
0.50 * Top Stage Depth or 2.5 Feet)
D) Total Volume: Voltot
= Storage from 5A + 6A + 6B Voltot
= acre-feet
(Must be > Design Volume in 1D, or 0.0216 acre-feet.)
7. Basin Side Slopes (Z, horizontal distance per unit vertical) Z = (horizontal/vertical)
Minimum Z = 4, Flatter Preferred
8. Dam Embankment Side Slopes (Z, horizontal distance) Z = (horizontal/vertical)
per unit vertical) Minimum Z = 3, Flatter Preferred
9. Vegetation (Check the method or describe "Other") Native Grass
Irrigated Turf Grass
Other:
Notes:
Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility
MM
Interwest Consulting Group
October 1, 2013
MVG - Morningstar Facility
DETENTION BASIN A (SW)
UD-BMP_v2.06.xls, EDB - SW POND 10/1/2013, 7:37 AM
Interwest Consulting Group
DETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
100-Year Event
LOCATION: MVG MORNINGSTAR - EXTENDED DETENTION BASIN A (SW)
PROJECT NO: 1173-105-00
COMPUTATIONS BY: MHM
DATE: 10/1/2013
Equations: Area trib. to pond = 1.24 acre
Developed flow = QD = CIA C (100) = 0.49
Vol. In = Vi = T C I A = T QD Developed C A = 0.6 acre
Vol. Out = Vo =K QPO T Release rate, QPO = 0.4 cfs
storage = S = Vi - Vo K = 0.9 (from fig 2.1)
Rainfall intensity from City of Fort Collins IDF Curve with updated (3.67") rainfall
Storm Rainfall QD Vol. In Vol. Out Storage Storage
Duration, T Intensity, I (cfs) Vi Vo S S
(min) (in/hr) (ft3) (ft3) (ft3) (ac-ft)
5 9.95 6.0 1814 117 1697 0.04
10 7.77 4.7 2831 234 2597 0.06
20 5.62 3.4 4098 469 3629 0.08
30 4.47 2.7 4887 703 4184 0.10
40 3.74 2.3 5454 937 4516 0.10
50 3.23 2.0 5895 1172 4723 0.11
60 2.86 1.7 6255 1406 4849 0.11
70 2.57 1.6 6561 1641 4920 0.11
80 2.34 1.4 6826 1875 4951 0.11
90 2.15 1.3 7060 2109 4951 0.11
100 1.99 1.2 7270 2344 4927 0.11
110 1.86 1.1 7461 2578 4883 0.11
120 1.75 1.1 7636 2812 4824 0.11
130 1.65 1.0 7798 3047 4751 0.11
140 1.56 0.9 7948 3281 4667 0.11
150 1.48 0.9 8088 3515 4573 0.10
160 1.41 0.9 8220 3750 4471 0.10
170 1.35 0.8 8345 3984 4361 0.10
180 1.29 0.8 8463 4218 4245 0.10
Required Storage Volume: 4951 ft3
0.11 acre-ft
detention.xls,FAA-100yr SW POND
EXTENDED DETENTION BASIN A (SW)
Proposed Detention Pond - Stage/Storage
LOCATION: MVG - Morningstar
PROJECT NO: 1173-105-00
COMPUTATIONS BY: MHM
SUBMITTED BY: INTERWEST CONSULTING GROUP
DATE: 10/1/2013
V = 1/3 d ( A + B + sqrt(A*B))
where V = volume between contours, ft3
d = depth between contours, ft
A = surface area of contour
Surface Incremental Detention Total
Stage Area Storage Storage Storage
(Elev) (Ft^2) (Ac-ft) (Ac-ft) (Ac-ft)
67.0 0
68.0 1319 0.01 0.010
WQ WSEL- 69.0 3696 0.06 0.00 0.065
69.25 4163 0.02 0.02 0.088
100-yr WSEL- 69.50 4868 0.03 0.03 0.114
SPILLWAY - 69.62 5120 0.01 0.04 0.128
TOP OF BERM - 70.12 0 0.02 0.05 0.147
Total Storage Req'd Storage
0.147 > 0.111
detention.xls
Sheet 1 of 3
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
Ia
= 47.00 %
A) Tributary Area's Imperviousness Ratio (i = Ia
/ 100 ) i = 0.47
B) Contributing Watershed Area (Area) Area = 3.180 acres
C) Water Quality Capture Volume (WQCV) WQCV = 0.20 watershed inches
(WQCV =1.0 * (0.91 * I
3
- 1.19 * I
2
+ 0.78 * I))
D) Design Volume: Vol = (WQCV / 12) * Area * 1.2 Vol = 0.0630 acre-feet
2. Outlet Works
A) Outlet Type (Check One) X Orifice Plate
Perforated Riser Pipe
Other:
B) Depth at Outlet Above Lowest Perforation (H) H = 2.00 feet
C) Recommended Maximum Outlet Area per Row, (Ao
) Ao
= 0.2 square inches
D) Perforation Dimensions:
i) Circular Perforation Diameter or D = 0.500 inches
ii) Width of 2" High Rectangular Perforations W = inches
E) Number of Columns (nc, See Table 6a-1 For Maximum) nc = 1 number
F) Actual Design Outlet Area per Row (Ao
) Ao
= 0.2 square inches
G) Number of Rows (nr) nr = 6 number
H) Total Outlet Area (Aot
) Aot
= 1.2 square inches
3. Trash Rack
A) Needed Open Area: At
= 0.5 * (Figure 7 Value) * Aot
At
= 43 square inches
B) Type of Outlet Opening (Check One) X < 2" Diameter Round
2" High Rectangular
Other:
C) For 2", or Smaller, Round Opening (Ref.: Figure 6a):
i) Width of Trash Rack and Concrete Opening (Wconc
)
from Table 6a-1 Wconc
= 3 inches
ii) Height of Trash Rack Screen (HTR
) HTR
= 54 inches
Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility
Interwest Consulting Group
MVG - Morningstar Facility
DETENTION BASIN B (NW)
October 1, 2013
MM
Sheet 2 of 3
Designer:
Company:
Date:
Project:
Location:
iii) Type of Screen (Based on Depth H), Describe if "Other" S.S. #93 VEE Wire (US Filter)
Other:
iv) Screen Opening Slot Dimension, Describe if "Other" 0.139" (US Filter)
Other:
v) Spacing of Support Rod (O.C.) inches
Type and Size of Support Rod (Ref.: Table 6a-2)
vi) Type and Size of Holding Frame (Ref.: Table 6a-2)
D) For 2" High Rectangular Opening (Refer to Figure 6b):
I) Width of Rectangular Opening (W) W = inches
ii) Width of Perforated Plate Opening (Wconc
= W + 12") Wconc
= inches
iii) Width of Trashrack Opening (Wopening
) from Table 6b-1 Wopening
= inches
iv) Height of Trash Rack Screen (HTR
) HTR
= inches
v) Type of Screen (based on depth H) (Describe if "Other") Klemp
TM
KPP Series Aluminum
Other:
vi) Cross-bar Spacing (Based on Table 6b-1, Klemp
TM
KPP inches
Grating). Describe if "Other" Other:
vii) Minimum Bearing Bar Size (Klemp
TM
Series, Table 6b-2)
(Based on depth of WQCV surcharge)
4. Detention Basin length to width ratio (L/W)
5 Pre-sedimentation Forebay Basin - Enter design values
A) Volume (3% to 5% of Design Volume from 1D) acre-feet
(3% - 5% of Design Volume (0.0019 - 0.0032 acre-feet.)
B) Surface Area acres
C) Connector Pipe Diameter inches
(Size to drain this volume in 5-minutes under inlet control)
D) Paved/Hard Bottom and Sides yes/no
MM
Interwest Consulting Group
Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility
October 1, 2013
MVG - Morningstar Facility
DETENTION BASIN B (NW)
UD-BMP_v2.06.xls, EDB - NW POND 10/1/2013, 7:39 AM
Sheet 3 of 3
Designer:
Company:
Date:
Project:
Location:
6. Two-Stage Design - See Figure EDB-1
A) Top Stage (Depth DWQ
= 2' Minimum) DWQ
= feet
Top Stage Storage: no less than 99.5% of Design Volume (0.0627 acre-feet.) Storage= acre-feet
B) Bottom Stage Depth (DBS
= 0.33' Minimum Below Trickle Channel Invert) DBS
= feet
Bottom Stage Storage: no less than 0.5% of Design Volume (0.0003 acre-feet.) Storage= acre-feet
Storage = A * Depth Above WS To Bottom Of Top Stage Surf. Area= acres
C) Micro Pool (Minimum Depth = the Larger of Depth= feet
0.50 * Top Stage Depth or 2.5 Feet)
D) Total Volume: Voltot
= Storage from 5A + 6A + 6B Voltot
= acre-feet
(Must be > Design Volume in 1D, or 0.063 acre-feet.)
7. Basin Side Slopes (Z, horizontal distance per unit vertical) Z = (horizontal/vertical)
Minimum Z = 4, Flatter Preferred
8. Dam Embankment Side Slopes (Z, horizontal distance) Z = (horizontal/vertical)
per unit vertical) Minimum Z = 3, Flatter Preferred
9. Vegetation (Check the method or describe "Other") Native Grass
Irrigated Turf Grass
Other:
Notes:
MM
Interwest Consulting Group
October 1, 2013
Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility
MVG - Morningstar Facility
DETENTION BASIN B (NW)
UD-BMP_v2.06.xls, EDB - NW POND 10/1/2013, 7:39 AM
Interwest Consulting Group
DETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
100-Year Event
LOCATION: MVG MORNINGSTAR - EXTENDED DETENTION BASIN B (NW)
PROJECT NO: 1173-105-00
COMPUTATIONS BY: MM
DATE: 10/1/2013
Equations: Area trib. to pond = 3.18 acre
Developed flow = QD = CIA C (100) = 0.59
Vol. In = Vi = T C I A = T QD Developed C A = 1.9 acre
Vol. Out = Vo =K QPO T Release rate, QPO = 1.1 cfs
storage = S = Vi - Vo K = 0.9 (from fig 2.1)
Rainfall intensity from City of Fort Collins IDF Curve with updated (3.67") rainfall
Storm Rainfall QD Vol. In Vol. Out Storage Storage
Duration, T Intensity, I (cfs) Vi Vo S S
(min) (in/hr) (ft3) (ft3) (ft3) (ac-ft)
5 9.95 18.7 5600 301 5300 0.12
10 7.77 14.6 8743 601 8142 0.19
20 5.62 10.5 12655 1202 11453 0.26
30 4.47 8.4 15090 1803 13287 0.31
40 3.74 7.0 16840 2404 14436 0.33
50 3.23 6.1 18202 3005 15197 0.35
60 2.86 5.4 19316 3606 15709 0.36
70 2.57 4.8 20258 4207 16051 0.37
80 2.34 4.4 21077 4808 16269 0.37
90 2.15 4.0 21800 5409 16391 0.38
100 1.99 3.7 22450 6010 16440 0.38
110 1.86 3.5 23039 6611 16428 0.38
120 1.75 3.3 23579 7212 16367 0.38
130 1.65 3.1 24078 7813 16265 0.37
140 1.56 2.9 24542 8414 16128 0.37
150 1.48 2.8 24976 9015 15961 0.37
160 1.41 2.6 25384 9616 15768 0.36
170 1.35 2.5 25769 10217 15551 0.36
180 1.29 2.4 26133 10818 15315 0.35
Required Storage Volume: 16440 ft3
0.38 acre-ft
detention.xls,FAA-100yr NW POND
EXTENDED DETENTION BASIN B (NW)
Proposed Detention Pond - Stage/Storage
LOCATION: MVG - Morningstar
PROJECT NO: 1173-105-00
COMPUTATIONS BY: MHM
SUBMITTED BY: INTERWEST CONSULTING GROUP
DATE: 10/1/2013
V = 1/3 d ( A + B + sqrt(A*B))
where V = volume between contours, ft3
d = depth between contours, ft
A = surface area of contour
Surface Incremental Detention Total
Stage Area Storage Storage Storage
(Elev) (Ft^2) (Ac-ft) (Ac-ft) (Ac-ft)
62.80 0
63.0 180
64.0 2168 0.02 0.02
WQ WSEL- 64.5 3813 0.03 0.00 0.06
65.0 5458 0.05 0.05 0.11
66.0 7535 0.15 0.20 0.26
100-yr WSEL- 67.0 9287 0.19 0.39 0.45
67.25 9822 0.05 0.45 0.51
SPILLWAY - 67.5 19298 0.08 0.53 0.59
TOP OF BERM - 68.0 0 0.07 0.60 0.66
Total Storage Req'd Storage
0.662 > 0.377
detention.xls
UD-BMP_v2.06.xls, EDB - NW POND 10/1/2013, 7:39 AM
UD-BMP_v2.06.xls, EDB - SW POND 10/1/2013, 7:37 AM