HomeMy WebLinkAboutOASIS ON OLIVE - FDP - FDP180018 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE RELATED DOCUMENT1218 W. ASH, STE. A, WINDSOR, COLORADO 80550
TEL. 970.674.3300 – FAX 970.674.3303
September 26, 2018
Mr. Wes Lamarque
Fort Collins Utilities – Stormwater
700 Wood Street
Fort Collins, CO 80522
Re: Oasis on Olive – 310 W. Olive Street
Final Storm Drainage Letter
Dear Wes,
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 310 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 located within the City regulated 100-yr Old Town Basin floodplain. The Master Plan was
prepared by Anderson Consulting Engineers, dated July 15, 2003. The project is not located within a
FEMA mapped 100-yr floodplain as shown within FIRM Map No. 08069C0979H though is within a
defined City of Fort Collins floodplain. Refer to the attached exhibits.
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.
Oasis on Olive
Final Storm Drainage Letter
September 26, 2018
Page 2 of 4
The proposed improvements will increase the impervious area to 7,401 sq-ft and will be approximately
70.3% impervious. Similar to the existing conditions, the site is divided into two (2) major drainage
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 bioretention / rain garden planters for treatment and surface flows
either sheet flow or are conveyed by a storm drain 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 3,558 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 the bioretention / 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). No portions
of the proposed structure is within the flood plain or floodway. 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 5001.85
ft. 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 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
bioretention / rain garden planters 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.
Due to the historical value of this site along with consideration of the adjacent historic buildings and the
heritage garden on site, it was approved with the City and the Landmark Preservation Commission, that
only 50% of the proposed impervious area is required for treatment with bioretention / rain garden
planters. Due to the roof configuration we are able to treat 48.5% of the overall proposed impervious
area.
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.
Oasis on Olive
Final Storm Drainage Letter
September 26, 2018
Page 3 of 4
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).
Runoff from the building roof will be conveyed to the bioretention / rain garden planters via roof drains.
The rain garden planters will slow runoff, 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 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
Oasis on Olive
Final Storm Drainage Letter
September 26, 2018
Page 4 of 4
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.
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
(approx site location)
Oasis on Olive
DRAINAGE SUMMARY
Design Engineer:
Design Firm:
Project Number:
Date:
IMPERVIOUS SUMMARY:
Description
Impervious
Area
%
Impervious
Existing 3,844 35.5%
Proposed 7,401 70.3%
Difference 3,558 34.8%
J.Claeys
Interwest Consulting Group
1335-176-00
July 18, 2018
1335-176-00 Rational Calcs (FC).xlsx Page 1 of 1 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
1335-176-00
July 18, 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 1,421 0.03 0 1,421 0 0 0 90.0% 0.95 1.00
D1b 1,364 0.03 0 1,132 0 0 232 74.7% 0.83 1.00
D1c 6,014 0.14 0 3,153 928 0 1,933 61.1% 0.72 0.91
D2 780 0.02 767 0 0 0 13 98.4% 0.94 1.00
Overall 9,579 0.22 767 5,706 928 0 2,177 70.3% 0.79 0.99
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
1335-176-00
July 18, 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 90.0% 0.95 0.033 26 0.3000 0.46 69 0.0195 Paved Areas 20 2.79 0.41 5.00 0.0959 5.00 5.00
1b D1b 74.7% 0.83 0.031 37 0.3000 0.98 145 0.0040 Paved Areas 20 1.26 1.91 5.00 0.0635 7.20 5.00
1c D1c 61.1% 0.72 0.138 53 0.0186 4.15 166 0.0100 Paved Areas 20 2.00 1.38 5.53 0.0121 10.08 5.53
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
July 18, 2018
Oasis on Olive
DEVELOPED TIME OF CONCENTRATION
J.Claeys
Interwest Consulting Group
1335-176-00
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 90.0% 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 74.7% 1.00 0.031 37 0.3000 0.36 145 0.0040 Paved Areas 20 1.26 1.91 5.00 0.0635 7.20 5.00
2A D1c 61.1% 0.91 0.138 53 0.0186 2.15 166 0.0100 Paved Areas 20 2.00 1.38 5.00 0.0121 10.08 5.00
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
July 18, 2018
Oasis on Olive
DEVELOPED TIME OF CONCENTRATION
J.Claeys
Interwest Consulting Group
1335-176-00
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 0.95 0.03 2.78 0.09 5.00 0.95 0.03 4.87 0.15 5.00 1.00 0.03 9.95 0.32
1b D1b 0.031 5.00 0.83 0.03 2.78 0.07 5.00 0.83 0.03 4.87 0.13 5.00 1.00 0.03 9.95 0.31
1c D1c 0.138 5.53 0.72 0.10 2.70 0.27 5.53 0.72 0.10 4.61 0.46 5.00 0.91 0.13 9.95 1.24
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
1335-176-00
July 18, 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 4 of 4 Interwest Consulting Group
Oasis on Olive
Low Impact Development
Design Engineer:
Design Firm:
Project Number:
Date:
DESIGN CRITERIA
Low Impact Development Summary
Pavement Area Summary
767 sqft
0 sqft
0.0%
Developed Area Summary
7,401 sqft
Total Area required for Treatment (50%): 3,701 sqft
0 sqft
0 sqft
0 sqft
3,588 sqft
3,588 sqft
48.5%
Total New Impervious Area:
J.Claeys
Interwest Consulting Group
1335-176-00
July 18, 2018
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.
- Per Landmark Preservation Committee coordination & acceptance, LID treated area may be reduced to
50% of impervious area.
Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, January 2010
Total New Paved Area:
Permeable Paver Area:
Percent Pavement Area as Permeable Pavers:
Proposed Area of Pavers:
Additional Area Treated by Pavers:
Total Area Treated by Pavers:
Impervious Area Treated by Rain Garden Planters:
Total Area Treated by LID:
Percent Site Area Treated by LID:
1 & 2, BLOCK 92
LOT 2
LOT 1
LOT 3
310 W. OLIVE ST.
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
310 W. OLIVE STREET
LID EXHIBIT
07/18/18
1"= 5'
N/A
JTC
RA
1335-176-00
1 of 1
THIS OLD HOWES, LLC
561 YORK STREET
DENVER, CO 80209
PHONE: 970.484.5907
CONTACT: STEVE SLEZAK
SCALE: 1" =
0
5'
5 2.5 5 10
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 = 1,421 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 = 38.0 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 = 38.75 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 38.75 sq ft
F) Rain Garden Total Volume VT= 38.75 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
July 18, 2018
Oasis on Olive
Rain Garden Planters (West - 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 - West).xlsm, RG 7/19/2018, 8:51 AM
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
July 18, 2018
Oasis on Olive
Rain Garden Planters (West - 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 - West).xlsm, RG 7/19/2018, 8:51 AM
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 = 1,129 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 = 30.2 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 = 20 sq ft
D) Actual Flat Surface Area AActual = 31.25 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 31.25 sq ft
F) Rain Garden Total Volume VT= 31.25 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
July 18, 2018
Oasis on Olive
Rain Garden Planters (North - 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 Planters - North).xlsm, RG 7/19/2018, 8:51 AM
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
July 18, 2018
Oasis on Olive
Rain Garden Planters (North - 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 Planters - North).xlsm, RG 7/19/2018, 8:51 AM
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 = 586 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 = 15.7 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 = 11 sq ft
D) Actual Flat Surface Area AActual = 16.25 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 16.25 sq ft
F) Rain Garden Total Volume VT= 16.25 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
July 18, 2018
Oasis on Olive
Rain Garden Planters (East - Basin D1c)
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 - East).xlsm, RG 7/19/2018, 8:54 AM
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
July 18, 2018
Oasis on Olive
Rain Garden Planters (East - Basin D1c)
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 - East).xlsm, RG 7/19/2018, 8:54 AM
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 = 452 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 = 12.1 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 = 8 sq ft
D) Actual Flat Surface Area AActual = 12.50 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 12.50 sq ft
F) Rain Garden Total Volume VT= 12.50 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
July 18, 2018
Oasis on Olive
Rain Garden Planters (East Tower - Basin D1c)
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 - East Tower).xlsm, RG 7/19/2018, 8:56 AM
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
July 18, 2018
Oasis on Olive
Rain Garden Planters (East Tower - Basin D1c)
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 - East Tower).xlsm, RG 7/19/2018, 8:56 AM
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 3 of 4 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 2 of 4 Interwest Consulting Group
(sq feet)
Awalk
(sq feet)
Agravel/pavers
(sq feet)
Alawn
(sq feet)
1335-176-00 Rational Calcs (FC).xlsx Page 1 of 4 Interwest Consulting Group
Walks/RAP
Gravel/Pavers
1335-176-00 Rational Calcs (FC).xlsx Page 1 of 1 Interwest Consulting Group