HomeMy WebLinkAbout2106 SOUTH TAFT HILL ROAD SINGLE FAMILY - PDP - PDP170002 - REPORTS - DRAINAGE REPORTPRELIMINARY DRAINAGE REPORT
TAFT HILL VILLAGE
Fort Collins, Colorado
March 7, 2017
Prepared for:
John, Albert, and Samuel Minatta
1313 Fairway Five Drive
Fort Collins, CO 80525
Prepared by:
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 1076-001
This Drainage Report is consciously provided as a PDF.
Please consider the environment before printing this document in its entirety.
When a hard copy is absolutely necessary, we recommend double-sided printing.
March 7, 2017
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage Report for
Taft Hill Village
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage Report for your review. This
report accompanies the Conceptual Review submittal for the proposed Taft Hill Village.
This report has been prepared in accordance with the City of Fort Collins Stormwater Criteria
Manual (FCSCM) and the Urban Drainage and Flood Control District (UDFCD) Urban Storm
Drainage Criteria Manual and serves to document the stormwater impacts associated with the
proposed Taft Hill Village project. We understand that review by the City of Fort Collins is to assure
general compliance with standardized criteria.
If you should have any questions as you review this report, please feel free to contact us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
Bud Curtiss Blaine Mathisen
Vice President Project Engineer
Taft Hill Village
Preliminary Drainage Report
TABLE OF CONTENTS
I. General Location and Description ............................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 1
C. Floodplain.......................................................................................................................................... 2
II. drainage basins and sub-basins .................................................................................. 3
A. Major Basin Description .................................................................................................................... 3
B. Sub-Basin Description ....................................................................................................................... 3
III. drainage DESIGN CRITERIA ...................................................................................... 4
A. Regulations........................................................................................................................................ 4
B. Four Step Process .............................................................................................................................. 4
C. Development Criteria Reference and Constraints ............................................................................ 5
D. Hydrological Criteria ......................................................................................................................... 5
E. Hydraulic Criteria .............................................................................................................................. 5
F. Floodplain Regulations Compliance .................................................................................................. 6
G. Modifications of Criteria ................................................................................................................... 6
IV. drainage FACILITY DESIGN ....................................................................................... 6
A. General Concept ............................................................................................................................... 6
B. Specific Details .................................................................................................................................. 7
V. CONCLUSIONS ........................................................................................................ 9
A. Compliance with Standards .............................................................................................................. 9
B. Drainage Concept .............................................................................................................................. 9
References ....................................................................................................................... 10
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations
B.1 – Detention Facilities
APPENDIX C – Water Quality Design Computations
APPENDIX D – Erosion Control Report
APPENDIX E – Soils Resource Report
LIST OF TABLES AND FIGURES:
Figure 1 - Aerial Photograph - Google Earth ............................................................................ 1
Figure 2 - Proposed Site Plan ............................................................................................... 2
Figure 3 - Existing City Floodplain ......................................................................................... 3
Figure 4 - LID Table ............................................................................................................ 4
Taft Hill Village
Preliminary Drainage Report
MAP POCKET:
C6.00 - Drainage Exhibit
C6.01 – Historic Drainage Exhibit
Taft Hill Village
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
Figure 1 - Aerial Photograph - Google Earth
2. Taft Hill Village is in Township 7 North, Range 69 West of the 6th P.M., City of Fort
Collins, County of Larimer, State of Colorado.
3. The project site is located on the east side of Taft Hill Villagenear the intersection of
Taft Hill Villageand Sheffield Dr. It is directly across the street from Blevins Middle
School. The project site is surrounded by residential homes to the north, east, and
south.
4. Currently the existing lot remains mostly undeveloped. However, there is currently a
two-story house with an associated detached garage and landscaping. This house has
a historical tag and therefore cannot be demolished but instead must be incorporated
into the over plan for the proposed subdivision. The house sits along the western
property line adjacent to the pedestrian cross walk across S. Taft Hill.
B. Description of Property
1. Taft Hill Village project site is 2.35 net acres. Taft Hill Village is not proposing any
improvements to Taft Hill VillageRd. However, due the lack of storm sewer
infrastructure the proposed project will be discharging east into Dover Dr. through a
sidewalk chase therefore additional offsite improvements will be necessary near the
south-east corner of the project site. Also, Taft Hill Village will leave the historical
house untouched other than two landscaping walls that jutted to far south into the
private drive isle. Overall, the proposed site will maintain the historic drainage
Taft Hill Village
Preliminary Drainage Report 2
patterns.
2. Taft Hill Village will be maintaining the overall historic drainage characteristics of this
site. There are currently no water quality amenities or even any storm infrastructure.
Taft Hill Village is not proposing any storm infrastructure at this time but will be
constructing several water quality amenities, this will be discussed in Section IV.B.
There is also no offsite runoff entering the site from Taft Hill VillageRd.
3. Per the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey, 100 percent of the site consists of Altvan-
Satanta loams, which fall into Hydrologic Soil Groups B.
4. The proposed development will include the clearing of existing vegetation, two (2)
tress, the removal of 180 sf. of sidewalk where the proposed entrance is and the
removal of roughly 135 sf. of concrete walls behind the existing detached garage.
Figure 2 - Proposed Site Plan
5. There are no irrigation facilities, erosion buffer zones, or major drainage ways within
the property limits.
6. The project site is within a Low Density Residential zoning district. Therefore, the
proposed use is permitted within this zone district.
C. Floodplain
1. The subject property does not lie within a FEMA floodplain. The project site falls
within the FIRM Panel 08069C986G for Larimer County, dated May 2nd, 2012.
2. Taft Hill Village does not fall within a city floodplain.
Taft Hill Village
Preliminary Drainage Report 3
Figure 3 - Existing City Floodplain
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. Taft Hill Village is within the Canal Importation drainage basin. This basin, which
suffered significant property damage in the flood of 1997, is almost completely
urbanized with primarily mixed density residential and isolated commercial land uses.
Runoff from the basin empties into the Old Town or Spring creek basins.
2. There are no previous drainage studies for the area associated with this project site.
B. Sub-Basin Description
1. Taft Hill Village historically sheet flows from the northwest towards the southeast
corner of the project site. This historic condition will be maintained to the best of the
engineer’s ability.
Basin H1
Basin H1 is associated with the entire project site and has an overall area of 2.35
acres. Basin H1 has one two story house with a detached garage and an associated
gravel driveway. There is currently no stormwater infrastructure or water quality
amenities. Additionally, there are no offsite flows entering Basin H1. Basin H1 has a
historic 2-year flow of 0.81 cfs.
2. A more detailed description of the projects proposed drainage patterns follows in
Section IV.A.4., below.
Taft Hill Village
Preliminary Drainage Report 4
3. There are no offsite flows associated with Taft Hill Village.
4. A full-size copy of the Historic and Proposed Drainage Exhibit can be found in the
Map Pocket at the end of this report.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the Taft Hill Village
project.
B. Four Step Process
The overall stormwater management strategy employed with the Taft Hill Village project
utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving
waters. The following is a description of how the proposed development has incorporated
each step.
Step 1 – Employ Runoff Reduction Practices
Several techniques have been utilized with the proposed development to facilitate the
reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the
current use by implementing multiple Low-Impact Development (LID) strategies including:
Providing as much vegetated open areas as possible along the north, east, west and
south portion of the site to reduce the overall impervious area and to minimize directly
connected impervious areas (MDCIA).
Routing flows, to the extent feasible, through either a bio-swale or across concrete
pavers.
Providing on-site detention to increase time of concentration, promote infiltration and
reduce loads on downstream storm infrastructure.
Below is a table that shows the breakdown of the proposed LID amenities compared to the
proposed impervious area.
Figure 4 - LID Table
The porous pavers compose of exactly 25% of the Private Drive aisle.
Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with
Slow Release
The efforts taken in Step 1 will facilitate the reduction of runoff and provide the necessary
BMPs required for water quality. Stormwater generated along the northern portion of the
Design
Point
Basin ID Basin Area Treatment Type
LID
System
Impervious Area
Treated by LID
System
Percent of
Impervious Area
Treated by LID
System
a1 A1 0.557 ac. Bio-Swale Yes 0.067 ac. 9.03%
b1 B1 0.725 ac. Pavers Yes 0.385 ac. 51.89%
b1 B2 0.452 ac.
Extended
Detention
No 0.142 ac. 0.00%
a2 A2 0.618 ac.
Extended
Detention
No 0.148 ac. 0.00%
Total 2.352 ac. 0.742 ac. 61%
Taft Hill Village
Preliminary Drainage Report 5
project site will sheet flow north where it will be collected and routed through a bio-swale.
Runoff generated near the middle of the project site will sheet flow south across the
private drive aisle where it will pass over concrete pavers. Eventually all the runoff is
routed to the pond that borders the southern property line where it will be released at the
historic 2-year runoff.
Step 3 – Stabilize Drainageways
As stated in Section I.B.5, above, there are no drainageways associated with the project
site.
Step 4 – Implement Site Specific and Other Source Control BMPs.
This step typically applies to industrial and commercial developments and is not
applicable for this project.
C. Development Criteria Reference and Constraints
1. There are no known drainage studies for the existing property.
2. The subject property is essentially an "in-fill" development project as the property is
surrounded by currently developed properties. As such, several constraints have been
identified during this analysis that will impact the proposed drainage system
including:
Existing elevations along the east, west, north, and south property lines will be
maintained.
During the construction of Taft Hill Village, it is imperative that the house that
currently sites on the project site remains untouched except for the two concrete
walls behind the detached garage that will need to be removed.
Overall drainage patterns of the existing site will be maintained.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
associated with this development. Tabulated data contained in Table RA-7 has been
utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
3. The Rational Formula-based Modified Federal Aviation Administration (FAA)
procedure has been utilized for detention storage calculations.
4. Two separate design storms have been utilized to address distinct drainage scenarios.
The first event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year
recurrence interval. The second event considered is the “Major Storm,” which has a
100-year recurrence interval.
5. No other assumptions or calculation methods have been used with this development
that are not referenced by current City of Fort Collins criteria.
E. Hydraulic Criteria
1. As previously noted, the subject property historically drains from the northwest to the
southeast. The entire site drains stormwater via overland flow.
2. All drainage facilities proposed with the Taft Hill Village project are designed in
Taft Hill Village
Preliminary Drainage Report 6
accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood
Control District’s (UDFCD) Urban Storm Drainage Criteria Manual.
3. As stated in Section I.C.1, above, the subject property is not located within a City
regulatory floodplain.
4. Taft Hill Village does not propose to modify any natural drainageways.
F. Floodplain Regulations Compliance
1. As previously mentioned, the project site does not fall within a City regulatory
floodplain.
G. Modifications of Criteria
The proposed Taft Hill Village development is requesting that the required amount of
freeboard be reduced from a foot to six (6) inches. Due to the lack of space for the
detention ponds and to insure the walls along the southern property edge can tie into
existing grade and still be under 30” tall Pond A has a freeboard height of 6.12”.
Pond B has a freeboard height of 6.96”.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the Taft Hill Village drainage design is to maintain existing
drainage patterns and ensure no adverse impacts to any adjacent properties or
existing infrastructure.
2. As previously mentioned, there are no off-site flows draining onto the existing
property.
3. A list of tables and figures used within this report can be found in the Table of
Contents at the front of the document. The tables and figures are located within the
sections to which the content best applies.
4. Taft Hill Village has been broken down into four major drainage basins, designated as
Basins A1, B1, B2, and A2.
Basin A1
Basin A1 is located along the northern third of the project site. Runoff from Basin A1
is generated from roofs, back porches, and landscaping. Basin A1 sheet flows south to
north where it is collected in bio-swale. The bio-swale conveys the collected runoff
towards a 2’ concrete pan that runs north to south along the eastern property line
which discharges the runoff into the Pond A along the southern border of the site.
From there the runoff will be released east into a swale and concrete chase into Dover
Drive at the historic 2-year rate.
Basin B1
Basin B1 is in the middle of the project site and drains stormwater via overland flow
from the north to the south. Runoff from Basin B1 is generated from roofs, driveways,
sidewalk, landscaping, and the drive aisle. All the runoff generated in Basin B1 sheet
flows across concrete pavers that are in the middle of the drive aisle. Once, the runoff
has been treated by the concrete pavers an underdrain system will then convey the
Taft Hill Village
Preliminary Drainage Report 7
runoff south into Pond A. Once discharged into Pond A the runoff will then be
released east into a swale and concrete chase into Dover Drive at the historic 2-year
rate.
Basin B2
Basin B2 wraps around the southwest corner of the project site and drains via
overland flow from north to south. Runoff from Basin B2 is generated from the drive
aisle entrance, the roof of the existing house, and landscaping areas. All of the runoff
generated in Basin B2 will initially be collected in Pond B1 and just like Basin B1 it
will then be released into Pond A2 and then conveyed to Dover Drive at the historic 2-
year rate.
Basin A2
Basin A2 encompasses the southeast corner of the project site. Runoff from Basin A2
is generated from the two eastern most lots of the proposed subdivision and a portion
of the cul-de-sac and the associated sidewalk. Stormwater from Basin A2 splits flows
at the ridge of the two lots. Runoff generated on the eastern side of the lots will sheet
flow east where it will be collected in a 2’ concrete pan and runoff generated on the
western side of the lots will sheet flow north to south. However, both scenarios will
convey the runoff to Pond A. From Pond A the runoff will be conveyed to Dover Drive
via a swale and concrete chase just like Basins A1, B1, and B2.
B. Specific Details
1. The main drainage problems associated with this project site is the deficiency of
existing stormwater infrastructure present and lack of developable area.
Basins A1, B1, B2, and A2 will all be treated either by an LID amenity or via
extended detention.
A restrictor plate will be placed at the outfall of Pond A to ensure that the site is
not discharging at a rate greater than the 2-year.
Pond B and Pond A were both sized using a reduced historic 2-year release rate.
Ultimately though, Pond A will be releasing the entire site at the historic 2-year
release rate.
2. The release rate for the undeveloped land (pre-development) was established by
calculating the Historic 2-year peak runoff rate for the entire project area (Basin H1)
with no reduction because all the runoff generated on the site is being captured and
treated. The overall historic 2-year peak runoff rate was calculated to be 0.81 cfs.
This release rate was utilized in the FAA procedure detention storage computations
(Refer to Appendix B for these calculations).
3. Detention Pond Calculations
Taft Hill Village has two ponds that are right next to one another and act hydraulically
independent of each other. Pond B is situated directly west of Pond A and they are
separated by a berm and headwall that has a weir and restrictor plate on it.
However, Pond A will have all runoff from the site eventually passing through it
because it is the ultimate discharge location. Pond A will discharge east into a
proposed swale and concrete chase into Dover Drive at the historic 2-year rate. Pond
B will be releasing into Pond A and Pond A will be releasing into the proposed swale
and concrete chase conveying the flows towards Dover Drive.
Taft Hill Village
Preliminary Drainage Report 8
Pond A
The FAA method was used to size Pond A. The overall historic 2-year release rate is
0.81 cfs and Pond A was sized using a release rate of 0.61 cfs and Pond B was
sized using a release rate of 0.20 cfs. Based on the characteristics of Basins A1 and
A2 with an adjusted release rate of 0.61 cfs, formulate a detention volume of 7058
cu. ft. However, Basin A2 is receiving water quality in the form of extended detention
and following UDFCD standards Basin A2 requires 277.49 cu. ft. of volume for water
quality. Therefore, the required volume for the 100-yr detention plus the WQCV is
7335.49 cu ft. The top of pond for Pond A is at an elevation of 5084.09’ and the
top of freeboard is at 5084.60’ therefore there is slightly more than 6 inches of free
board (6.12”). Pond A will be releasing at the full 2-year historic rate (0.81 cfs) and
the emergency flow for Pond A is at the southeast corner of the site and discharges
east into the swale that will convey the flows into Dover Drive.
Pond B
The FAA method was used to size Pond B as well. As mentioned in the description of
Pond A, Pond B was sized using a release rate of 0.20 cfs. The reason different flow
rates were used in sizing the two ponds was because Pond B is in a spot within the
project site that allows for a larger pond. Based on characteristics from Basins B1
and B2 with an adjusted release rate of 0.20 cfs, formulate a detention volume of
7906 cu. ft. However, Basin B2 will is receiving water quality in the form of
extended detention and following UDFCD standards Basin B2 requires 242.27 cu. ft.
of volume for water quality. Basin B1 is receiving its water quality through the porous
pavers. Therefore, the required volume for the 100-yr detention plus the WQCV is
8148.27 cu. ft. The top of Pond B is at an elevation of 5085.02’ and the top of
freeboard is at 5085.60 therefore there is slightly more than 6 inches of free board
(6.96”). Pond B will release at a rate of 0.20 cfs into Pond A through a pipe that
connects the two ponds. Once into Pond A it will release at the historic 2-year rate of
0.81 cfs with Pond A’s runoff. The emergency spillway for Pond B is located at the
headwall that divides Pond A and Pond B. The excess runoff will flow east until it
reaches the swale east of Pond A where it will be conveyed to Dover Drive.
4. Water Quality Results
Basin A1
All runoff generated in Basin A1 will enter the bio-swale that is located adjacent to
the northern property line. The bio-swale is a landscaped element designed to
concentrate and/or remove silt and pollution from surface runoff water. Currently,
there are no concrete standards on how to properly size bio-swales but a 10:1 runoff
ratio cannot be exceeded. The runoff ratio is a comparison between the impervious
area and surface area of the bio-swale (impervious area of basin:bio-swale surface
area). Basin A1’s bio-swale has an overall surface area of 1833 sq. ft. and the total
impervious area of Basin A1 is 2920 sq. ft. Therefore, the runoff ratio is 1.6:1 which
is well below the required 10:1 ratio.
Basin B1
Basin B1 will have water quality provided via concrete pavers located in the middle
of the private drive aisle. Following UDFCD standards, a required WQCV for Basin B1
is 390 cu. ft. and the volume provided within the permeable pavers is 693 cu. ft.
Once the runoff has gone through the permeable pavers it will be conveyed to Pond A
via a 6” perforated pipe.
Taft Hill Village
Preliminary Drainage Report 9
Basin B2
Water quality for Basin B2 will be provided via extended detention in Pond B.
Following UDFCD Standards, a required WQCV for Basin B2 is 247 cu. ft. This
volume is included within Pond B. Pond B will have an outlet structure located at
design point b1 that detains and attenuates runoff and promotes the settlement of
pollutants.
Basin A2
Water quality for Basin A2 will also be provide via extended detention in Pond A.
Following UDFCD Standards, a required WQCV for Basin A2 is 278 cu. ft. This
volume is included within in Pond A. Pond A will have an outlet structure located at
design point a2 that detains and attenuates runoff and promotes the settlement of
pollutants.
5. Pond B’s emergency overflow conveys excess runoff east over the
berm/headwall into Pond A. Pond A’s emergency overflow path is located at
design point a2. From there all excess flow will overtop the pond wall and
flow east via swale into Dover Drive. Both Pond B and Pond A have a free
board of roughly 6 inches (6.12”).
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the Taft Hill Village project complies with the City
of Fort Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with the Taft Hill Village project complies with the City
of Fort Collins’ Master Drainage Plan.
3. There are no city regulatory floodplains and/or erosion buffer zones associated with
the Taft Hill Village project.
4. The drainage plan and stormwater management measures proposed with the Taft Hill
Village development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit potential damage
associated with its stormwater runoff. Taft Hill Village will detain and treat the entire
project site and release at the historic 2-year rate east into Dover Drive during the
developed 100-year storm.
2. Taft Hill Village will provide water quality via LID features as well as extended
detention.
Taft Hill Village
Preliminary Drainage Report 10
References
1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities,
November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services.
2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No.
174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code.
3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
APPENDIX A
HYDROLOGIC COMPUTATIONS
Brickstone Apartments
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: South Taft Hill
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen
Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….0.. 50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year C
f = 1.00 100-year C
f = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Pavers
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
H1 102457.9 2.352 0.000 0.025 0.043 0.124 0.000 2.16 0.28 0.28 0.35 5%
TOTAL 102458 2.352 0.000 0.025 0.043 0.124 0.000 2.16 0.19 0.19 0.24 5%
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
10-year Cf
Brickstone Apartments
Overland Flow, Time of Concentration:
Project: South Taft Hill
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt
= L / 60V
Tc
= Ti
+ Tt
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf
=1.00)
C*Cf
(10-yr
Cf
=1.00)
C*Cf
(100-yr
Cf
=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Brickstone Apartments
Rational Method Equation: Project: South Taft Hill
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
h1 H1 2.35 33 33 31 0.28 0.28 0.35 1.22 2.08 4.47 0.81 1.39 3.72
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
B. Mathisen
January 19, 2017
Q = C f ( C )( i )( A )
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Brickstone Apartments
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
h1 H1 2.35 0.28 0.35 33.2 30.7 0.81 3.72
Page 7 of 23 Proposed D:\Projects\1076-001\Drainage\Hydrology\1076-001_Historic Rational-Calcs.xlsx\SUMMARY-TABLE
Brickstone Apartments
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: South Taft Hill
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen
Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….0.. 50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year C
f = 1.00 100-year C
f = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Pavers
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
A1 24263.9 0.557 0.000 0.023 0.047 0.000 0.000 0.49 0.34 0.34 0.42 11%
B1 31583.0 0.725 0.000 0.170 0.149 0.000 0.071 0.34 0.57 0.57 0.72 42%
B2 19673.7 0.452 0.000 0.127 0.019 0.000 0.000 0.31 0.48 0.48 0.60 29%
A2 26936.5 0.618 0.000 0.080 0.069 0.000 0.000 0.47 0.42 0.42 0.52 22%
TOTAL 102457 2.352 0.000 0.400 0.284 0.000 0.071 1.67 0.39 0.39 0.49 26%
Brickstone Apartments
Overland Flow, Time of Concentration:
Project: South Taft Hill
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt
= L / 60V
Tc
= Ti
+ Tt
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf
=1.00)
C*Cf
(10-yr
Cf
=1.00)
C*Cf
(100-yr
Cf
=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Brickstone Apartments
Rational Method Equation: Project: South Taft Hill
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
a1 A1 0.56 17 17 16 0.34 0.34 0.42 1.75 2.99 6.41 0.33 0.56 1.51
b1 B1 0.73 7 7 5 0.57 0.57 0.72 2.52 4.31 9.95 1.05 1.79 5.16
b1 B2 0.45 10 10 8 0.48 0.48 0.60 2.26 3.86 8.38 0.49 0.83 2.26
a2 A2 0.62 8 8 7 0.42 0.42 0.52 2.46 4.21 9.06 0.64 1.09 2.93
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
B. Mathisen
January 23, 2017
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Q = C f ( C )( i )( A )
Page 3 of 23 Proposed D:\Projects\1076-001\Drainage\Hydrology\1076-001_Rational-Calcs.xlsx\Direct-Runoff
Brickstone Apartments
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
a1 A1 0.56 0.34 0.42 17.1 15.6 0.33 1.51
b1 B1 0.73 0.57 0.72 7.4 5.4 1.05 5.16
b1 B2 0.45 0.48 0.60 9.8 8.3 0.49 2.26
a2 A2 0.62 0.42 0.52 7.6 6.7 0.64 2.93
Page 7 of 23 Proposed D:\Projects\1076-001\Drainage\Hydrology\1076-001_Rational-Calcs.xlsx\SUMMARY-TABLE
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 – Detention Facilities
APPENDIX B.1
DETENTION FACILITIES
Pond No :
a2
100-yr
0.52
6.30 min 7058 ft3
1.36 acres 0.162 ac-ft
Max Release Rate = 0.61 cfs
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 2111 1.00 0.61 183 1928
10 7.720 3276 0.82 0.50 298 2977
15 6.520 4150 0.71 0.43 390 3760
20 5.600 4752 0.66 0.40 481 4271
25 4.980 5283 0.63 0.38 573 4710
30 4.520 5754 0.61 0.37 664 5089
35 4.080 6059 0.59 0.36 756 5303
40 3.740 6348 0.58 0.35 847 5501
45 3.460 6607 0.57 0.35 939 5668
50 3.230 6853 0.56 0.34 1030 5822
55 3.030 7071 0.56 0.34 1122 5950
60 2.860 7281 0.55 0.34 1213 6068
65 2.720 7502 0.55 0.33 1305 6197
70 2.590 7693 0.55 0.33 1396 6297
75 2.480 7892 0.54 0.33 1488 6405
80 2.380 8079 0.54 0.33 1579 6500
85 2.290 8259 0.54 0.33 1671 6589
90 2.210 8440 0.54 0.33 1762 6677
95 2.130 8586 0.53 0.33 1854 6732
100 2.060 8741 0.53 0.32 1945 6796
105 2.000 8911 0.53 0.32 2037 6874
110 1.940 9055 0.53 0.32 2128 6927
115 1.890 9223 0.53 0.32 2220 7003
120 1.840 9369 0.53 0.32 2311 7058
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
A =
Tc =
Project Location :
Design Point
C =
Design Storm
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
Invert Elevation
Water Quality Volume
100-yr Detention Volume
Total Pond Volume
Min Sc
D = Depth between contours (ft.)
A1
= Surface Area lower contour (ft
2
) t
A2
= Surface Area upper contour (ft
2
) Area/Row
No. of Rows
5082.20 170.82 0.00 0.00 0.00 0.0000
5082.40 798.07 0.20 89.21 89.21 0.0020
5082.60 1565.84 0.20 232.12 321.33 0.0074 WQCV
5082.80 2502.34 0.20 403.18 724.50 0.0166
5083.00 3616.63 0.20 608.49 1332.99 0.0306
5083.20 4557.27 0.20 815.58 2148.57 0.0493
5083.40 5154.55 0.20 970.57 3119.14 0.0716
5083.60 5640.89 0.20 1079.18 4198.32 0.0964
5083.80 6251.10 0.20 1188.68 5386.99 0.1237
5084.00 6821.74 0.20 1306.87 6693.86 0.1537
5084.20 7394.76 0.20 1421.26 8115.13 0.1863 Total Vol
5084.40 7980.53 0.20 1537.16 9652.28 0.2216
5084.60 8596.82 0.20 1657.35 11309.64 0.2596
Elevation Depth Volume
WQCV 5082.56 0.36 0.0064
100-yr Detention 5084.05 1.85 0.1620
Overall Detention 5084.09 1.89 0.1684
Circular Perforation Sizing
Dia (in.)
1
Pond A
0.05
5
0.0064 ac-ft
5082.20 ft
Pond A Volume
Elevation
(ft)
n
1/4
0.018 sq-in
Surface
Area (ft2) Total Outlet
Area
0.25 sq. in.
Taft Hill Village 3/7/2017
1076-001 B. Mathisen
0.0000
0.1684 ac-ft
0.1620 ac-ft
Required Area
Pond No :
b1
100-yr
0.66
5.00 min 7906 ft3
0.99 acres 0.182 ac-ft
Max Release Rate = 0.20 cfs
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 1950 1.00 0.20 60 1890
10 7.720 3027 0.75 0.15 90 2937
15 6.520 3834 0.67 0.13 120 3714
20 5.600 4391 0.63 0.13 150 4241
25 4.980 4881 0.60 0.12 180 4701
30 4.520 5316 0.58 0.12 210 5106
35 4.080 5598 0.57 0.11 240 5358
40 3.740 5865 0.56 0.11 270 5595
45 3.460 6104 0.56 0.11 300 5804
50 3.230 6331 0.55 0.11 330 6001
55 3.030 6533 0.55 0.11 360 6173
60 2.860 6727 0.54 0.11 390 6337
65 2.720 6931 0.54 0.11 420 6511
70 2.590 7108 0.54 0.11 450 6658
75 2.480 7292 0.53 0.11 480 6812
80 2.380 7464 0.53 0.11 510 6954
85 2.290 7631 0.53 0.11 540 7091
90 2.210 7798 0.53 0.11 570 7228
95 2.130 7933 0.53 0.11 600 7333
100 2.060 8076 0.53 0.11 630 7446
105 2.000 8233 0.52 0.10 660 7573
110 1.940 8366 0.52 0.10 690 7676
115 1.890 8521 0.52 0.10 720 7801
120 1.840 8656 0.52 0.10 750 7906
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
1076-001
South Taft Hill
Project Number :
Project Name :
Pond B
A =
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
Invert Elevation
Water Quality Volume
100-yr Detention Volume
Total Pond Volume
Min Sc
D = Depth between contours (ft.)
A1
= Surface Area lower contour (ft
2
) t
A2
= Surface Area upper contour (ft
2
) Area/Row
No. of Rows
5083.20 194.77 0.00 0.00 0.00 0.0000
5083.40 811.59 0.20 93.60 93.60 0.0021
5083.60 1718.55 0.20 247.41 341.01 0.0078 WQCV
5083.80 2931.71 0.20 459.66 800.66 0.0184
5084.00 4439.40 0.20 731.92 1532.58 0.0352
5084.20 5751.29 0.20 1016.24 2548.82 0.0585
5084.40 6558.62 0.20 1230.11 3778.93 0.0868
5084.60 6861.29 0.20 1341.88 5120.81 0.1176
5084.80 7146.38 0.20 1400.67 6521.48 0.1497
5085.00 7465.95 0.20 1461.12 7982.59 0.1833 100-yr Vol
5085.20 7820.36 0.20 1528.49 9511.09 0.2183 Total Vol
5085.40 8188.25 0.20 1600.72 11111.81 0.2551
5085.60 9272.45 0.20 1744.95 12856.76 0.2952
Elevation Depth Volume
WQCV 5083.52 0.32 0.0056
100-yr Detention 5084.99 1.79 0.1820
Overall Detention 5085.02 1.82 0.1876
Circular Perforation Sizing
Dia (in.)
1
Pond B
0.05
5
0.0056 ac-ft
5083.20 ft
Pond B Volume
Elevation
(ft)
n
1/4
0.016 sq-in
Surface
Area (ft2) Total Outlet
Area
0.25 sq. in.
Taft Hill Village 3/7/2017
1076-001 B. Mathisen
0.1876 ac-ft
0.1820 ac-ft
Required Area
Per Row
APPENDIX C
WATER QUALITY DESIGN COMPUTATIONS
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
1
WQCV = Watershed inches of Runoff (inches) 22.00%
a = Runoff Volume Reduction (constant)
i = Total imperviousness Ratio (i = Iwq/100) 0.124 in
A = 0.62 ac
V = 0.0064 ac-ft 277.49 cu. ft.
V = Water Quality Design Volume (ac-ft)
WQCV = Water Quality Capture Volume (inches)
A = Watershed Area (acres)
Drain Time
a =
i =
WQCV =
Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event
South Taft Hill January 23, 2017
1076-001 B. Mathisen
Pond A
0.124
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
WQCV (watershed inches)
Total Imperviousness Ratio (i = Iwq
/100)
Water Quality Capture Volume
6 hr
12 hr
24 hr
40 hr
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
V * A
12
WQCV
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
1
WQCV = Watershed inches of Runoff (inches) 29.00%
a = Runoff Volume Reduction (constant)
i = Total imperviousness Ratio (i = Iwq/100) 0.148 in
A = 0.45 ac
V = 0.0056 ac-ft 242.27 cu. ft.
V = Water Quality Design Volume (ac-ft)
WQCV = Water Quality Capture Volume (inches)
A = Watershed Area (acres)
South Taft Hill January 23, 2017
1076-001 B. Mathisen
Pond B
Drain Time
a =
i =
WQCV =
Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event
0.148
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
WQCV (watershed inches)
Total Imperviousness Ratio (i = Iwq
/100)
Water Quality Capture Volume
6 hr
12 hr
24 hr
40 hr
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
V * A
12
WQCV
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Type of Permeable Pavement Section
A) What type of section of permeable pavement is used?
(Based on the land use and activities, proximity to adjacent
structures and soil characteristics.)
B) What type of wearing course?
2. Required Storage Volume
A) Effective Imperviousness of Area Tributary to Permeable Pavement, Ia Ia = 42.0 %
B) Tributary Area's Imperviousness Ratio (I = Ia / 100) i = 0.420
C) Tributary Watershed Area ATotal = 31,583 sq ft
(including area of permeable pavement system)
D) Area of Permeable Pavement System APPS = 3,080 sq ft
(Minimum recommended permeable pavement area = 5481 sq ft)
E) Impervious Tributary Ratio RT = 3.9 IMPERVIOUS TRIBUTARY RATIO EXCEEDS 2.0
(Contributing Imperviuos Area / Permeable Pavement Ratio)
F) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 390 cu ft
(WQCV = (0.8 * (0.91 * i3 - 1.19 * i2 + 0.78 * i) / 12) * Area)
G) Is flood control volume being added?
H) Total Volume Needed VTotal = cu ft
3. Depth of Reservoir
A) Minimum Depth of Reservoir Dmin = 10.0 inches
(Minimum recommended depth is 6 inches)
B) Is the slope of the reservoir/subgrade interface equal to 0%?
C) Porosity (Porous Gravel Pavement < 0.3, Others < 0.40) P = 0.30
D) Slope of the Base Course/Subgrade Interface S = ft / ft
E) Length Between Lateral Flow Barriers L = ft
F) Volume Provided Based on Depth of Base Course V = 693 cu ft
Flat or Stepped: V = P * ((Dmin-1)/12) * Area
Sloped: V = P * [(Dmin - (Dmin - 6*SL-1)) / 12] * Area
4. Lateral Flow Barriers
A) Type of Lateral Flow Barriers
B) Number of Permeable Pavement Cells Cells = 1
5. Perimeter Barrier
A) Is a perimeter barrier provided on all sides of the
pavement system?
(Recommeded for PICP, concrete grid pavement, or for any
no-infiltration section.)
South Taft Hill
Basin B1
Design Procedure Form: Permeable Pavement Systems (PPS)
Blaine Mathisen
Northern Engineering
January 23, 2017
Choose One
No Infiltration
Partial Infiltration Section
Full Infiltration Section
Choose One
YES
NO
Choose One
YES- Flat or Stepped Installation
NO- Sloped Installation
Choose One
Concrete Walls
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
6. Filter Material and Underdrain System
A) Is the underdrain placed below a 6-inch thick layer of
CDOT Class C filter material?
B) Diameter of Slotted Pipe (slot dimensions per Table PPs-2)
Detention Vault no Underdrain
C) Distance from the Lowest Elevation of the Storage Volume y = 0.3 ft
(i.e. the bottom of the base course to the center of the orifice)
7. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is there a minimum 30 mil thick impermeable PVC geomembrane
liner on the bottom and sides of the basin, extending up to the top
of the base course?
B) CDOT Class B Separator Fabric
8. Outlet
(Assumes each cell has similar area, subgrade slope, and length
between lateral barriers (unless subgrade is flat). Calculate cells
individually where this varies.)
A) Depth of WQCV in the Reservoir DWQCV = 5.06 inches
(Elevation of the Flood Control Outlet)
B) Diameter of Orifice for 12-hour Drain Time DOrifice = 0.67 inches
(Use a minimum orifice diameter of 3/8-inches)
Notes:
Basin B1
South Taft Hill
Design Procedure Form: Permeable Pavement Systems (PPS)
Blaine Mathisen
Northern Engineering
January 23, 2017
Choose One
YES
NO
Choose One
4-inch
6-inch
Choose One
Choose One
YES
NO
Placed above the liner
Placed above and below the liner
N/A
1076-001 Basin B1 PAVER UD-BMP_v3.02.xls, PPS 1/23/2017, 4:10 PM
APPENDIX D
EROSION CONTROL REPORT
South Taft Hill
Final Erosion Control Report
A comprehensive Erosion and Sediment Control Plan (along with associated details) will be included
with the final construction drawings. It should be noted, however, that any such Erosion and
Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of
the BMPs depicted, and additional or different BMPs from those included may be necessary during
construction, or as required by the authorities having jurisdiction.
It shall be the responsibility of the Contractor to ensure erosion control measures are properly
maintained and followed. The Erosion and Sediment Control Plan is intended to be a living
document, constantly adapting to site conditions and needs. The Contractor shall update the
location of BMPs as they are installed, removed or modified in conjunction with construction
activities. It is imperative to appropriately reflect the current site conditions at all times.
The Erosion and Sediment Control Plan shall address both temporary measures to be implemented
during construction, as well as permanent erosion control protection. Best Management Practices
from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are
not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways
and inlet protection at proposed storm inlets. Vehicle tracking control pads, spill containment and
clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall
also be provided by the Contractor.
Grading and Erosion Control Notes can be found on Sheet CB2 of the Utility Plans. The Utility
Plans at final design will also contain a full-size Erosion Control Plan as well as a separate sheet
dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the
Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing
Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior
to issuance of the Development Construction Permit. Also, the Site Contractor for this project will
be required to secure a Stormwater Construction General Permit from the Colorado Department of
Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program,
before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor
shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE
requirements and guidelines. The SWMP will further describe and document the ongoing activities,
inspections, and maintenance of construction BMPs.
MAP POCKET
HISTORIC DRAINAGE EXHIBIT
PROPOSED DRAINAGE EXHIBIT
CONTROL
CONTROL IRR
IRR G
T
T
CTV
CTV
CTV
CTV
CTV CTV
G
G
T
T
T
T
T
W
X
S
S
M
W
X
X
X
X
SS
SS SS SS SS
M
X
X
X
X
X X
X
X
X
X
X
X X
X
X
X
X X X
X
X
X
X
X
X
16" W 16" W 16" W 16" W 16" W 16" W 16" W 16" W
H1
LOT 5
OWNER: BLACK J/M/S OWNER: BLACK M/J
LOT 8 LOT 21 LOT 22
LOT 23
VILLAGE WEST NINTH FILING
VILLAGE WEST FOURTH FILING
VILLAGE WEST THIRD FILING
CONTROL
CONTROL IRR
IRR G
CTV
G
G
W
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X X
X
X
X
X X X
X
X
X
X
X
X
LOT 5
OWNER: BLACK J/M/S OWNER: BLACK M/J
LOT 8 LOT 21 LOT 22
LOT 23
VILLAGE WEST NINTH FILING
VILLAGE WEST FOURTH FILING
VILLAGE WEST THIRD FILING
LOT 1 LOT 2 LOT 3 LOT 4
LOT 6
LOT 5 LOT 4
SOUTH TAFT HILL
(ROW VARIES)
B1
A1
A2
a2
a1
B2
UD
UD
UD
UD
UD
UD
UD
UD UD
UD
UD
UD
UD
UD UD UD UD UD
b1
20' EMERGENCY
12' UTILITY ACCESS EASEMENT
EASEMENT
15' DRAINAGE
EASEMENT
6' UTILITY
EASEMENT
LOT 1
LOT 8
LOT 7
LOT 5 LOT 6
LOT 4
LOT 3
LOT 2
TRACT A WQCV EXTENTS
WQCV EXTENTS
4' CURB
CUT
POND B
STORAGE VOLUME=8148.27 CU. FT.
100-YR ELEV.=5084.96
WQCV ELEV.=5083.52
POND A
STORAGE VOLUME=7335.49 CU. FT.
100-YR ELEV.=5084.09
WQCV ELEV.=5082.57
FES A1
OUTLET
STRUCTURE
DRYWELL
FLAT BOTTOM
BIO-SWALE
EXISTING INLET GRATE
EXISTING DECID. TREE
EXISTING CONIF. TREE
EXISTING LIGHT POLE
EXISTING STUMP
EXISTING CURB/GUTTER FLOWLINE
4950
4:1
BANK SLOPE
PROPOSED OVERLAND FLOW DIRECTION
CONCENTRATED FLOW DIRECTION
PROPOSED CONTOUR
EXISTING CONTOUR
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
A2
a3
DRAINAGE BASIN AREA
DESIGN POINT
DRAINAGE BASIN ID
DRAINAGE BASIN MINOR/MAJOR COEFF.
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
1. REFER TO THE "PRELIMINARY DRAINAGE REPORT FOR SOUTH TAFT HILL" BY
NORTHERN ENGINEERING, DATED 03/07/2017 FOR ADDITIONAL INFORMATION.
LID TABLE:
Sheet
of 11
TAFT HILL VILLAGE These drawings are
instruments of service
provided by Northern
Engineering Services, Inc.
and are not to be used for
any type of construction
unless signed and sealed by
a Professional Engineer in
the employ of Northern
Engineering Services, Inc.
NOT FOR CONSTRUCTION
REVIEW SET
200 South College Avenue, Suite 010
Fort Collins, Colorado 80524
E NGINEER ING
N O R T H E RN
PHONE: 970.221.4158 FAX: 970.221.4159
www.northernengineering.com
C6.00
DRAINAGE EXHIBIT
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
10
LEGEND:
LEGEND:
PROPOSED BIO-SWALE
TOP OF POND ELEVATION
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
a1 A1 0.56 0.34 0.42 17.1 15.6 0.33 1.51
b1 B1 0.73 0.57 0.72 7.4 5.4 1.05 5.16
b1 B2 0.45 0.48 0.60 9.8 8.3 0.49 2.26
a2 A2 0.62 0.42 0.52 7.6 6.7 0.64 2.93
SUMMARY TABLE:
WQCV ELEVATION
PROPOSED POROUS PAVERS
Design
Point Basin ID Basin Area Treatment Type
LID
System
Impervious Area
Treated by LID
System
Percent of
Impervious Area
Treated by LID
System
a1 A1 0.557 ac. Bio-Swale Yes 0.067 ac. 9.03%
b1 B1 0.725 ac. Pavers Yes 0.385 ac. 51.89%
b1 B2 0.452 ac. Extended
Detention No 0.142 ac. 0.00%
a2 A2 0.618 ac. Extended
Detention No 0.148 ac. 0.00%
Total 2.352 ac. 0.742 ac. 61%
PROPOSED 18" VERTICAL CURB AND GUTTER
LOT 1 LOT 2 LOT 3 LOT 4
LOT 6
LOT 5 LOT 4
SOUTH TAFT HILL
(ROW VARIES)
h1
Sheet
of 11
TAFT HILL VILLAGE These drawings are
instruments of service
provided by Northern
Engineering Services, Inc.
and are not to be used for
any type of construction
unless signed and sealed by
a Professional Engineer in
the employ of Northern
Engineering Services, Inc.
NOT FOR CONSTRUCTION
REVIEW SET
200 South College Avenue, Suite 010
Fort Collins, Colorado 80524
E NGINEER ING
N O R T H E RN
PHONE: 970.221.4158 FAX: 970.221.4159
www.northernengineering.com
4:1
City Engineer Date
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer
Date
Water & Wastewater Utility
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
Environmental Planner
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
A2
a3
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
1. REFER TO THE "PRELIMINARY DRAINAGE REPORT FOR SOUTH TAFT HILL" BY
NORTHERN ENGINEERING, DATED 03/07/2017 FOR ADDITIONAL INFORMATION.
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
LEGEND:
LEGEND:
C6.01
HISTORIC DRAINAGE EXHIBIT
11
SUMMARY TABLE:
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
h1 H1 2.35 0.28 0.35 33.2 30.7 0.81 3.72
PVC geomembrane installed normal to flow
N/A- Flat installation
Other (Describe):
Choose One
YES
NO
Choose One
PICP
Concrete Grid Pavement
Pervious Concrete
Porous Gravel
1076-001 Basin B1 PAVER UD-BMP_v3.02.xls, PPS 1/23/2017, 4:10 PM
=
40 hr
=
40 hr
Total Vol.
(ac-ft)
Total Vol.
(ft3)
Incremental
Vol. (ft3)
Incremental
Depth (ft)
Calc.
Depths
( )
3
* *
1 2 1 2
D A A A A
V = + +
Tc =
Project Location :
Design Point
C =
Design Storm
Page 1 of 1
1076-001_DetentionVolume_PondB_FAAModified Method.xls
Per Row
Total Vol.
(ac-ft)
Total Vol.
(ft3)
Incremental
Vol. (ft3)
Incremental
Depth (ft)
Calc.
Depths
( )
3
* *
1 2 1 2
D A A A A
V = + +
1076-001
South Taft Hill
Project Number :
Project Name :
Pond A
Page 1 of 1
1076-001_DetentionVolume_PondA_FAAModified Method.xls
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
a1 A1 No
0.34 0.34 0.42 95 1.20% 13.1 13.1 11.6 N/A N/A 380 1.10% 1.57 4.0 17 17 16
b1 B1 No
0.57 0.57 0.72 113 2.90% 7.4 7.4 5.4 N/A N/A N/A N/A N/A 7 7 5
b1 B2 No
0.48 0.48 0.60 75 1.90% 8.1 8.1 6.6 255 1.60% 2.53 1.7 N/A N/A N/A 10 10 8
a2 A2 No
0.42 0.42 0.52 70 6.40% 5.7 5.7 4.9 170 0.60% 1.55 1.8 N/A N/A N/A 8 8 7
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter/Pipe Flow Swale Flow
Design
Point
Basin
Overland Flow
B. Mathisen
January 23, 2017
Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
Page 2 of 23 Proposed D:\Projects\1076-001\Drainage\Hydrology\1076-001_Rational-Calcs.xlsx\Tc-10-yr_&_100-yr
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
10-year Cf
= 1.00
January 23, 2017
**Soil Classification of site is Clay Loam**
Page 1 of 23 Proposed D:\Projects\1076-001\Drainage\Hydrology\1076-001_Rational-Calcs.xlsx\C-Values
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
h1 H1 No
0.28 0.28 0.35 435 1.30% 29.2 29.2 26.7 N/A N/A 380 1.10% 1.57 4.0 33 33 31
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter/Pipe Flow Swale Flow
Design
Point
Basin
Overland Flow
B. Mathisen
January 19, 2017
Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
Page 2 of 23 Proposed D:\Projects\1076-001\Drainage\Hydrology\1076-001_Historic Rational-Calcs.xlsx\Tc-10-yr_&_100-yr
= 1.00
January 19, 2017
**Soil Classification of site is Clay Loam**
Page 1 of 23 Proposed D:\Projects\1076-001\Drainage\Hydrology\1076-001_Historic Rational-Calcs.xlsx\C-Values