HomeMy WebLinkAboutOASIS ON OLIVE - PDP - PDP180003 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE RELATED DOCUMENT1218 W. ASH, STE. A, WINDSOR, COLORADO 80550
TEL. 970.674.3300 – FAX 970.674.3303
March 14, 2018
Ms. Heather McDowell
Fort Collins Utilities – Stormwater
700 Wood Street
Fort Collins, CO 80522
Re: Oasis on Olive – 312 W. Olive Street
Preliminary Storm Drainage Letter
Dear Heather,
Please accept the following letter describing the storm drainage intent demonstrating the proposed site
improvement’s ability to comply with the City’s stormwater requirements.
INTRODUCTION
The Oasis on Olive proposes to construct a condominium building with supporting utility infrastructure,
site accesses (pedestrian/vehicular). The site is located along the north side of W. Olive St., between S.
Howes St. and S. Meldrum St., addressed as 312 W. Olive Street. A vicinity map is attached for
reference.
EXISTING CONDITIONS
The project site is located within the Udall drainage basin and standard water quality is not required. The
existing site consists of two (2) parking garages, pedestrian pathways, driveways, and gardens. The total
site is approximately 0.22 acres and currently site has approximately 3,844 sq-ft of impervious area and is
35.5% impervious. There are two (2) drainage basins to describe the drainage paths. The larger basin
(Basin H1) surface drains south to W. Olive St. A narrow basin (Basin H2) describes the private drive
that surface drains west to Canyon Ave. The garages, driveways, and pathways are all to be removed to
accommodate the proposed improvements. The Owner would like to preserve as much of the existing
gardens as possible. The gardens are generally located in the southeast corner of the site.
We are not aware of any site-specific drainage studies for this lot.
The project is not located within a FEMA mapped 100-yr floodplain though is within a defined City of
Fort Collins floodplain.
PROPOSED DEVELOPMENT
The improvements proposed will consist of a 3 story multi-family building, with tuck under parking, and
will include the supporting utility infrastructure and pedestrian/vehicle accesses. The project is planned to
be constructed in a single phase.
The proposed improvements will increase the impervious area to 7,062 sq-ft and will be approximately
67.1% impervious. Similar to the existing conditions, the site is divided into two (2) major drainage
Oasis on Olive
Preliminary Storm Drainage Letter
March 14, 2018
Page 2 of 4
basins to describe the drainage paths. Basin D1 consists of the area draining to W. Olive St. and is
divided into three (3) sub-basins for conveyance and Low Impact Development calculations. Runoff
within these basins are directed to rain gardens for treatment and surface flows through proposed
sidewalk chases to W. Olive St. Basin D2 consists of the improved east-west private drive. Runoff is
collected in a curb and gutter and directed to Canyon Ave, similar to the historic drainage path.
The proposed improvements create an increase in impervious area 3,218 sq-ft and is under the increase of
5,000 sq-ft which would require onsite detention. Standard water quality is provided downstream within
the Udall Basin and is not required onsite. A combination of a rain garden and rain garden planters are
proposed to provide water quality enhancement and are designed to satisfy the Low Impact Development
(LID) requirements.
All calculations and exhibits are attached for reference.
CITY FLOODPLAIN/FLOODWAY
An existing floodplain/floodway exists within and along W. Olive St. The driveway extending from W.
Olive St into the site is proposed to be improved. The elevations along the driveway are designed to
match, or be slightly less that the existing grades within this area, with the intent to not effect or change
the floodplain/floodway elevations. Per the City’s flood maps, cross-section 3164 extends through the
site near the upstream corner of the site. The base flood elevation is 5001.48 ft (NAVD88). The
regulatory flood protection elevation is 5002.98 ft (NAVD 88). To ensure that we are compliant with the
no-rise requirement, the driveway elevations are unable to be raised and the garage entries are at 5002.75
ft. Per the City’s floodplain requirements, the garages will be required to provide 1 sq-inch for every
square foot of enclosed area. Floodplain use permits are anticipated for the completion of the
improvements with the floodplain/floodway and a no-rise certification will be required for the certificate
of occupancy.
LOW IMPACT DEVELOPMENT TECHNIQUES
In reference to the code requirements for implementation of Low Impact Development (LID) techniques,
the use of a bioretention rain garden and rain garden planters are necessary to satisfy these requirements.
The rain garden will promote infiltration while capturing fine sediment that drains off of the impervious
areas. The rain garden planter will be lined due to the vicinity to the proposed building and will provide
filtration to remove fine sediment. A Standard Operations Procedure will be provided at final design to
assist in ensuring that these BMPs will adequately perform over time.
Below is a description of the 4 step process for selecting structural BMPs:
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 Impervious Areas (MDCIA).
Oasis on Olive
Preliminary Storm Drainage Letter
March 14, 2018
Page 3 of 4
Runoff throughout the site is mainly conveyed to the rain garden and rain garden planter via roof drains
and storm drains. The rain garden and rain garden planters will slow runoff, promote infiltration, and
filter runoff prior to being released into the adjacent storm drain system.
Step 2: Implement BMPs that Provide a Water Quality Capture Volume with Slow Release
The rain garden and rain garden planters are designed to provide water quality capture volume per Urban
Drainage’s recommendations and calculations. The captured runoff is design for a 12-hr drain time.
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. Because the site will drain to an existing
roadway and storm system, bank stabilization is unnecessary with this project.
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.
All calculations are attached for reference.
EROSION CONTROL
Erosion and sedimentation will be controlled on-site by use of sediment control logs, inlet protection, a
gravel construction entrance, seeding, mulch, and turf. 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 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 and sediment control logs
will require periodic replacement. Maintenance is the responsibility of the contractor.
Oasis on Olive
Preliminary Storm Drainage Letter
March 14, 2018
Page 4 of 4
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 and to survive severe weather condition.
Thank you in advance for your time and if you have any questions or comments please contact me at
(970) 347-8917.
Sincerely,
Jason T. Claeys, P.E., LEED AP
Interwest Consulting Group
Attachments
SITE
Vicinity Map
Scale: 1" = 1000'
PROJECT DATUM: NAVD88
CITY OF FORT COLLINS BENCHMARK #1-12
SOUTHEAST CORNER OF LAPORTE AVENUE AND WHITCOMB STREET, ON A STORM INLET ON
WHITCOMB STREET
ELEV= 5004.15
CITY OF FORT COLLINS BENCHMARK #6-00
ON A CATCH BASIN AT THE NORTHWEST CORNER OF MULBERRY ST. AND COLLEGE AVENUE
ELEV= 4993.85
PLEASE NOTE: THIS PLAN SET IS USING NAVD88 FOR A VERTICAL DATUM.
IF NGVD29 UNADJUSTED IS REQUIRED FOR ANY PURPOSE,
THE FOLLOWING EQUATIONS SHOULD BE USED:
NGVD UNADJUSTED = 5004.15 (NAVD88) - 3.18
NGVD UNADJUSTED = 4993.85 (NAVD88) - 3.17
Vicinity Map
1,128
188.1
Olive Street Condos
This map is a user generated static output from the City of Fort Collins FCMaps
Internet mapping site and is for reference only. Data layers that appear on this
map may or may not be accurate, current, or otherwise reliable.
City of Fort Collins - GIS
143.0
1:
WGS_1984_Web_Mercator_Auxiliary_Sphere
0 71.50 143.0 Feet
Notes
Legend
857
FEMA Floodplain
FEMA High Risk - Floodway
FEMA High Risk - 100 Year
FEMA Moderate Risk - 100 / 500 Year
FEMA Map Panel
City Floodplains
City High Risk - Floodway
City High Risk - 100 Year
City Moderate Risk - 100 Year
City Limits
Site Location
Oasis on Olive
Oasis on Olive
DRAINAGE SUMMARY
Design Engineer:
Design Firm:
Project Number:
Date:
IMPERVIOUS SUMMARY:
Description
Impervious
Area
%
Impervious
Existing 3,844 35.5%
Proposed 7,062 67.1%
Difference 3,218 31.5%
J.Claeys
Interwest Consulting Group
1335-176
March 14, 2018
1335-176-00 Rational Calcs (FC).xlsx Page 1 of 6 Interwest Consulting Group
WEST OLIVE STREET
CANYON AVENUE
LOT 3
LOT 2
LOT 1
SOUTH HOWES STREET
1218 W. Ash, Suite A
Windsor , Colorado 80550
Phone: (970) 674-3300
Fax: (970) 674-3303
I N T E R W E S T C O N S U L T I N G G R O U P
PREPARED FOR
PROJ. NO.
DATE:
SCALE (H):
SCALE (V):
CHECKED BY:
DESIGNED BY:
PROJECT NAME
OASIS ON OLIVE
HISTORIC DRAINAGE EXHIBIT
03/14/18
1" = 20'
N/A
JTC
JTC
1335-176-00
1 of 1
THIS OLD HOWES, LLC
561 YORK STREET
DENVER, CO 80209
PHONE: 970.484.5907
Design Engineer:
Design Firm:
Project Number:
Date:
%
Impervious
Runoff
Coefficient C
Return
Period
Frequency
Adjustment
Factor (Cf)
100% 0.95
2-year to
10-year
1.00
90% 0.95 100-year 1.25
90% 0.95
40% 0.50
0% 0.25
C2 to C10 C100
H1 8,922 0.205 0 1,090 1,945 0 5,888 30.6% 0.49 0.61
H2 809 0.019 0 0 809 0 0 90.0% 0.95 1.00
Overall 9,731 0.223 0 1,090 2,754 0 5,888 35.5% 0.53 0.66
Apavers
(sq feet)
Alawn
(sq feet)
Weighted %
Impervious
COMPOSITE
Oasis on Olive
EXISTING IMPERVIOUS AREA CALCULATION
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
DESIGN CRITERIA:
BASINS:
% Impervious values from Table RO-3 in the Urban Storm Drainage Criteria Manual
Sub-basin
Designation
Atotal
(sq feet)
Atotal
(acres)
Apaved
(sq feet)
Aroof
(sq feet)
Awalk/RAP
(sq feet)
Lawns
(Heavy, 2-7% Slope)
J.Claeys
Interwest Consulting Group
1335-176
March 14, 2018
Runoff Coefficients and Frequency Adjustment Factors for City of Fort Collins - Storm Water Criteria Manual
Land Use
Paved
Roof
Design Engineer:
Design Firm:
Project Number:
Date:
%
Impervious
Runoff
Coefficient C
Return
Period
Frequency
Adjustment
Factor (Cf
)
100% 0.95
2-year to
10-year
1.00
90% 0.95 100-year 1.25
90% 0.95
40% 0.50
0% 0.25
C2
to C10
C100
D1a 1,437 0.03 0 1,421 0 0 16 89.0% 0.94 1.00
D1b 6,108 0.14 0 4,284 307 0 1,517 67.7% 0.78 0.97
D1c 1,265 0.03 0 0 282 0 983 20.1% 0.41 0.51
D2 780 0.02 767 0 0 0 13 98.4% 0.94 1.00
Overall 9,590 0.22 767 5,706 589 0 2,528 67.1% 0.77 0.96
Oasis on Olive
DEVELOPED IMPERVIOUS AREA CALCULATION
DESIGN CRITERIA:
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
BASINS:
% Impervious values from Table RO-3 in the Urban Storm Drainage Criteria Manual
J.Claeys
Interwest Consulting Group
1335-176
March 14, 2018
Land Use
Paved
Roof
Walks
Runoff Coefficients and Frequency Adjustment Factors for City of Fort Collins - Storm Water Criteria Manual
Gravel/Pavers
Lawns
(Heavy, 2-7% Slope)
Sub-basin
Designation
Atotal
(sq feet)
Atotal
(acres)
Weighted %
Impervious
A COMPOSITE
paved
(sq feet)
Aroof
Design Engineer:
Design Firm:
Project Number:
Date:
EQUATIONS:
-Equation 6-2 -Equation 6-4 -Urbanized Check Equation 6-5
- CoFC Overland Flow
CONSTRAINTS:
300 ft - Overland flow shall not exceed for developed condition
500 ft - Overland flow shall not exceed for undeveloped condition
Final t c = minimum of t i + t t and urbanized basin check
recommended minimum t c = 5 min for urbanized basins
Time of Concentration (2-yr to 10-yr)
Type of Travel
Surface
Cv
1a D1a 89.0% 0.94 0.033 26 0.3000 0.48 69 0.0195 Paved Areas 20 2.79 0.41 5.00 0.0959 5.00 5.00
1b D1b 67.7% 0.78 0.140 37 0.3000 1.18 145 0.0040 Paved Areas 20 1.26 1.91 5.00 0.0635 8.28 5.00
1c D1c 20.1% 0.41 0.029 53 0.0186 7.68 36 0.0604 Lawns 7 1.72 0.35 8.03 0.0355 15.45 8.03
2 D2 98.4% 0.94 0.018 17 0.0266 0.90 43 0.0191 Paved Areas 20 2.76 0.26 5.00 0.0212 5.00 5.00
March 14, 2018
Oasis on Olive
DEVELOPED TIME OF CONCENTRATION
J.Claeys
Interwest Consulting Group
1335-176
LENGTH
(ft)
DESIGN CRITERIA:
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
Overland Flow Equations for City of Fort Collins - Storm Water Criteria Manual
SUB-BASIN DATA
INITIAL/OVERLAND TIME
(ti
)
TRAVEL TIME (tt
)
tc
=ti
+tt
(min)
Urban Check Final
tc
(min)
DESIGN
POINT
Sub-basin
%
Impervious
C2-10
AREA
(acres)
tt
(min)
OVERALL SLOPE
(ft/ft)
tc
(min)
SLOPE
(ft/ft)
Design Engineer:
Design Firm:
Project Number:
Date:
EQUATIONS:
-Equation 6-2 -Equation 6-4 -Urbanized Check Equation 6-5
- CoFC Overland Flow
CONSTRAINTS:
300 ft - Overland flow shall not exceed for developed condition
500 ft - Overland flow shall not exceed for undeveloped condition
Final t c = minimum of t i + t t and urbanized basin check
recommended minimum t c = 5 min for urbanized basins
Time of Concentration (100-yr)
Type of Travel
Surface
Cv
1A D1a 89.0% 1.00 0.033 26 0.3000 0.31 69 0.0195 Paved Areas 20 2.79 0.41 5.00 0.0959 5.00 5.00
1B D1b 67.7% 0.97 0.140 37 0.3000 0.47 145 0.0040 Paved Areas 20 1.26 1.91 5.00 0.0635 8.28 5.00
2A D1c 20.1% 0.51 0.029 53 0.0186 6.56 36 0.0604 Paved Areas 20 4.92 0.12 6.68 0.0355 15.45 6.68
2B D2 98.4% 1.00 0.018 17 0.0266 0.55 43 0.0191 Paved Areas 20 2.76 0.26 5.00 0.0212 5.00 5.00
March 14, 2018
Oasis on Olive
DEVELOPED TIME OF CONCENTRATION
J.Claeys
Interwest Consulting Group
1335-176
LENGTH
(ft)
DESIGN CRITERIA:
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised January 2016)
Overland Flow Equations for City of Fort Collins - Storm Water Criteria Manual
SUB-BASIN DATA
INITIAL/OVERLAND TIME
(ti
)
TRAVEL TIME (tt
)
tc
=ti
+tt
(min)
Urban Check Final
tc
(min)
DESIGN
POINT
Sub-basin
%
Impervious
C100
AREA
(acres)
tt
(min)
OVERALL SLOPE
(ft/ft)
tc
(min)
SLOPE
(ft/ft)
Design Engineer:
Design Firm:
Project Number:
Date:
EQUATIONS: I = rainfall intensity (in/hr)
Q n = n -yr peak discharge (cfs) P 1 = one-hour point rainfall depth (in)
C n = n -yr runoff coefficient t c = time of concentration (min)
I n = n -yr rainfall intensity (in/hr) P 1-2yr = 0.82 in
A n = Basin drainage area (ac) P 1-10yr = 1.40 in
P 1-100yr = 2.86 in
BASIN SUMMARY:
tc (min)
Runoff Coeff
(C2-10)
C(A) (acres)
Intensity
(in/hr)
Q (ft3/s) tc (min)
Runoff Coeff
(C2-10)
C(A) (acres)
Intensity
(in/hr)
Q (ft3/s) tc (min)
Runoff Coeff.
(C100)
C(A) (acres)
Intensity
(in/hr)
Q (ft3/s)
1a D1a 0.033 5.00 0.94 0.03 2.78 0.09 5.00 0.94 0.03 4.87 0.15 5.00 1.00 0.03 9.95 0.33
1b D1b 0.140 5.00 0.78 0.11 2.78 0.30 5.00 0.78 0.11 4.87 0.53 5.00 0.97 0.14 9.95 1.35
1c D1c 0.029 8.03 0.41 0.01 2.40 0.03 8.03 0.41 0.01 4.10 0.05 6.68 0.51 0.01 8.91 0.13
2 D2 0.018 5.00 0.94 0.02 2.78 0.05 5.00 0.94 0.02 4.87 0.08 5.00 1.00 0.02 9.95 0.18
10-yr Peak Runoff 100-yr Peak Runoff
Oasis on Olive
DEVELOPED PEAK RUNOFF
Urban Storm Drainage Criteria Manual by Urban Drainage and Flood Control District, June 2001 (Revised August 2006)
DESIGN CRITERIA:
Design
Point
Sub-basin Area (acres)
J.Claeys
Interwest Consulting Group
1335-176
March 14, 2018
2-yr Peak Runoff
Q n = C n I n A n
0.786651)
1
( 10 )
28 . 5
t c
P
I
+
=
1335-176-00 Rational Calcs (FC).xlsx Page 6 of 6 Interwest Consulting Group
Weir Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Wednesday, Feb 28 2018
Oasis on College - Rain Garden Spillway
Rectangular Weir
Crest = Broad
Bottom Length (ft) = 10.00
Total Depth (ft) = 0.25
Calculations
Weir Coeff. Cw = 2.60
Compute by: Known Q
Known Q (cfs) = 1.38
Highlighted
Depth (ft) = 0.14
Q (cfs) = 1.380
Area (sqft) = 1.41
Velocity (ft/s) = 0.98
Top Width (ft) = 10.00
0 1 2 3 4 5 6 7 8 9 10 11 12
Depth (ft) Oasis on College - Rain Garden Spillway Depth (ft)
-0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
Length (ft)
Weir W.S.
Oasis on Olive
Low Impact Development
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
Low Impact Development Summary
Pavement Area Summary
1,050 sqft
0 sqft
0.0%
Developed Area Summary
7,078 sqft
Total Area required for Treatment (75%): 5,309 sqft
0 sqft
0 sqft
0 sqft
6,028 sqft
6,028 sqft
85.2%
Impervious Area Treated by Rain Garden:
Proposed Area of Pavers:
Additional Area Treated by Pavers:
Total Area Treated by Pavers:
Total Area Treated by LID:
Percent Site Area Treated by LID:
Total New Paved Area:
Permeable Paver Area:
Percent Pavement Area as Permeable Pavers:
Total New Impervious Area:
J.Claeys
Interwest Consulting Group
1335-176-00
March 12, 2018
Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, January 2010
City of Fort Collins - Ordinance No. 007, 2016
- Treat at least 75% of any newly developed or redeveloped impervious area using one or a combination of
LID techniques, or
- Treat at least 50% of any newly developed or redeveloped impervious area using one or a combination of
LID techniques when 25% of private driveable surfaces are permeable.
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 90.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.900
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.32 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 1,437 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.43 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 38.5 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 0.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 26 sq ft
D) Actual Flat Surface Area AActual = 50 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 50 sq ft
F) Rain Garden Total Volume VT= 50 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
Modified CoFC Rain Garden Section (12" Growing Media, 4" Pea Gravel,
8" AASHTO Class 2)
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = N/A cu ft
iii) Orifice Diameter, 3/8" Minimum DO = N/A in
Design Procedure Form: Rain Garden (RG)
J.Claeys
Interwest Consulting Group
March 14, 2018
Oasis on Olive
Rain Garden Planters (Basin D1a)
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
1335-176-00 UD-BMP_v3.06 (RG Planters).xlsm, RG 3/12/2018, 1:36 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B
GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW
THE LINER IF THE SUBGRADE IS ANGULAR
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
J.Claeys
Interwest Consulting Group
March 14, 2018
Oasis on Olive
Rain Garden Planters (Basin D1a)
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
1335-176-00 UD-BMP_v3.06 (RG Planters).xlsm, RG 3/12/2018, 1:36 PM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 67.7 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.677
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.21 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 6,108 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.43 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 107.9 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 9 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 0.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 83 sq ft
D) Actual Flat Surface Area AActual = 150 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 150 sq ft
F) Rain Garden Total Volume VT= 113 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
Modified CoFC Rain Garden Section (12" Growing Media, 4" Pea Gravel
8" AASHTO Class 2)
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = N/A cu ft
iii) Orifice Diameter, 3/8" Minimum DO = N/A in
Design Procedure Form: Rain Garden (RG)
J. Claeys
Interwest Consulting Group
March 14, 2018
Oasis on Olive
Rain Garden (Basin D1b)
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
1335-176-00 UD-BMP_v3.06 (RG).xlsm, RG 3/12/2018, 1:35 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
J. Claeys
Interwest Consulting Group
March 14, 2018
Oasis on Olive
Rain Garden (Basin D1b)
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
1335-176-00 UD-BMP_v3.06 (RG).xlsm, RG 3/12/2018, 1:35 PM
ti
(min)
LENGTH
(ft)
SLOPE
(ft/ft)
Table RO-2 VELOCITY
(ft/s)
t c = t i + t t 0 . 5
V = C v S w
V
L
tt 60
=
��
= 18 − 15� +
�
60 24� + 12 �
��
=
1.87(1.1 − ��
��
) �
� �
1335-176-00 Rational Calcs (FC).xlsx Page 5 of 6 Interwest Consulting Group
ti
(min)
LENGTH
(ft)
SLOPE
(ft/ft)
Table RO-2 VELOCITY
(ft/s)
t c = t i + t t 0 . 5
V = C v S w
V
L
tt 60
=
��
= 18 − 15� +
�
60 24� + 12 �
��
=
1.87(1.1 − ��
��
) �
� �
1335-176-00 Rational Calcs (FC).xlsx Page 4 of 6 Interwest Consulting Group
(sq feet)
Awalk
(sq feet)
Agravel/pavers
(sq feet)
Alawn
(sq feet)
1335-176-00 Rational Calcs (FC).xlsx Page 3 of 6 Interwest Consulting Group
Walks/RAP
Gravel/Pavers
1335-176-00 Rational Calcs (FC).xlsx Page 2 of 6 Interwest Consulting Group