HomeMy WebLinkAboutTERRA VIDA II APARTMENTS - PDP - PDP130028 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTSeptember 4, 2013
PRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT FOR
TERRA VIDA 2 APARTMENTS
Fort Collins, Colorado
Prepared for:
Milestone Presidio, GP
1400 16th Street, 6th Floor
Denver, Colorado 80202
Prepared by:
200 South College Avenue, Suite 10
Fort Collins, Colorado 80524
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 514-002
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.
September 4, 2013
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage and Erosion Control Report for
TERRA VIDA 2 APARTMENTS
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report
for your review. This report accompanies the Project Development Plan submittal for the
proposed Terra Vida 2 Apartments development.
This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM),
and serves to document the stormwater impacts associated with the proposed project. We
understand that review by the City is to assure general compliance with standardized criteria
contained in the FCSCM.
If you should have any questions as you review this report, please feel free to contact us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
Aaron Cvar, PE
Project Engineer
Terra Vida 2 Apartments
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 2
C. Floodplain.......................................................................................................................................... 4
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4
A. Major Basin Description .................................................................................................................... 4
III. DRAINAGE DESIGN CRITERIA ................................................................................... 5
A. Regulations........................................................................................................................................ 5
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 6
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 6
G. Modifications of Criteria ................................................................................................................... 6
IV. DRAINAGE FACILITY DESIGN .................................................................................... 6
A. General Concept ............................................................................................................................... 6
B. Specific Details .................................................................................................................................. 8
V. CONCLUSIONS ........................................................................................................ 8
A. Compliance with Standards .............................................................................................................. 8
B. Drainage Concept .............................................................................................................................. 8
References ......................................................................................................................... 9
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Erosion Control Report
APPENDIX C - Banner Health Medical Campus Master Drainage Exhibit
APPENDIX D - Precision Drive Drainage Plan
Terra Vida 2 Apartments
Preliminary Drainage Report
LIST OF TABLES AND FIGURES:
Figure 1 – Aerial Photograph .................................................................................................. 2
Figure 2– Proposed Site Plan .................................................................................................. 3
Figure 3 – Existing Floodplains ............................................................................................... 4
MAP POCKET:
Proposed Drainage Exhibit
Terra Vida 2 Apartments
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. The project site is located in the northeast quarter of Section 4, Township 6 South,
Range 68 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer,
State of Colorado The project site is located on the east side of Lady Moon Drive, and
just north of Precision Drive
3. The project site lies within the East Harmony portion of the McClellands Creek Master
Drainage Basin. Per the “East Harmony Portion of the McClellands Creek Master
Drainage Plan Update”, by Icon Engineering, August 1999 (Ref. 6), onsite detention
is required with a release rate of 0.5 cfs per acre in the 100-year storm event.
4. Areas directly adjacent to the project site on the west, east are currently undeveloped.
The Terra Vida 1 Apartments (submitted as “Presidio Apartments”, Ref. 6) exist just
to the south of the project site. The existing Hewlett Packard campus is located just
north of the project site on the north side of Harmony Road. The Fossil Creek
Reservoir Inlet Ditch is located roughly 1/4 mile east of the site.
Terra Vida 2 Apartments
Preliminary Drainage Report 2
5. Any offsite flows that would enter the site on the west are intercepted by the existing
Lady Moon Drive storm line.
B. Description of Property
1. The development area is roughly 10.2 net acres.
Figure 1 – Aerial Photograph
2. The subject property currently consists mostly of vacant ground. There are three
existing residential lots and associated structures along Lady Moon Drive, that are to
be incorporated into this development. Existing ground cover generally consists of
open pasture and some native seeding. Existing ground slopes are generally mild
(i.e., 1 to 5±%) through the interior of the property. General topography slopes from
west to east towards the Fossil Creek Reservoir Inlet Ditch
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey website:
http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx,
the site consists of Paoli fine sandy loam, which falls into Hydrologic Soil Group B.
4. The proposed project will develop the majority of the existing site, constructing an
apartment complex. Parking areas and associated utilities will be constructed. The
Detention/water quality pond currently under review with the Banner Health Medical
Campus which will to be constructed just to the northeast of the site has been
designed to incorporate all necessary detention, water quality, and L.I.D. (Low Impact
Design) requirements for the Terra Vida 2 site.
Terra Vida 2 Apartments
Preliminary Drainage Report 3
Figure 2– Proposed Site Plan
5. The Fossil Creek Reservoir Inlet Ditch is located roughly 1/4 mile east of the project
site, and runs parallel to the site from north to south. There are no other major
irrigation ditches or related facilities in the vicinity of the project site.
6. The proposed land use is an apartment complex.
Terra Vida 2 Apartments
Preliminary Drainage Report 4
C. Floodplain
1. The project site is not encroached by any City or FEMA floodplain.
Figure 3 –Area Floodplain Mapping
2. No offsite improvements are proposed with the project.
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
3. The project site is located within the East Harmony portion of the McClellands Creek
Master Drainage Basin.
B. Sub-Basin Description
4. The subject property historically drains overland towards the Fossil Creek Reservior
Inlet Ditch, located roughly 1400 feet east of the project site. A more detailed
description of the project drainage patterns follows in Section IV.A.4., below.
5. Areas to the east of the site drain into an existing storm line within Lady Moon Drive
and are conveyed south in the existing storm system.
PROJECT
SITE
Terra Vida 2 Apartments
Preliminary Drainage Report 5
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the proposed
project.
B. Four Step Process
The overall stormwater management strategy employed with the proposed 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:
Conserving existing amenities in the site including the existing vegetated areas.
Providing vegetated open areas throughout the site to reduce the overall impervious
area and to minimize directly connected impervious areas (MDCIA).
Routing flows, to the extent feasible, through vegetated swales to increase time of
concentration, promote infiltration and provide initial water quality.
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; however, urban
development of this intensity will still generate stormwater runoff that will require
additional BMPs and water quality. The majority of stormwater runoff from the site will
ultimately be intercepted and treated using extended detention methods prior to exiting the
site.
Step 3 – Stabilize Drainageways
There are no major drainageways within the subject property. While this step may not
seem applicable to proposed development, the project indirectly helps achieve stabilized
drainageways nonetheless. By providing water quality where none previously existed,
sediment with erosion potential is removed from the downstream drainageway systems.
Furthermore, this project will pay one-time stormwater development fees, as well as
ongoing monthly stormwater utility fees, both of which help achieve City-wide drainageway
stability.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
Trash, waste products, etc. that were previously left exposed with the historic trailer
park will no longer be allowed to exposure to runoff and transport to receiving
drainageways. The proposed development will eliminate these sources of potential
pollution.
Terra Vida 2 Apartments
Preliminary Drainage Report 6
C. Development Criteria Reference and Constraints
The subject property is tied currently developed properties adjacent to the site. Thus,
several constraints have been identified during the course of this analysis that will
impact the proposed drainage system including:
Existing elevations along the property lines will generally be maintained.
As previously mentioned, overall drainage patterns of the existing site will be
maintained.
Elevations of existing downstream facilities that the subject property will release to
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 the proposed 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. Three separate design storms have been utilized to address distinct drainage
scenarios. A fourth design storm has also been computed for comparison purposes.
The first design storm considered is the 80th percentile rain event, which has been
employed to design the project’s water quality features. The second event analyzed is
the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The third
event considered is the “Major Storm,” which has a 100-year recurrence interval.
The fourth storm computed, for comparison purposes only, is the 10-year event.
4. 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 maintains historic drainage patterns.
2. All drainage facilities proposed with the project are designed in accordance with
criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District
(UDFCD) Urban Storm Drainage Criteria Manual.
3. As stated above, no part of the subject property is located in a City or FEMA
regulatory floodplain.
4. The proposed project does not propose to modify any natural drainageways.
F. Modifications of Criteria
1. The proposed development is not requesting any modifications to criteria at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the project drainage design are to maintain existing drainage
patterns, and to ensure no adverse impacts to any adjacent properties.
Terra Vida 2 Apartments
Preliminary Drainage Report 7
2. The offsite detention/water quality pond, referred to as the “ODP Pond”, currently
under review with the Banner Health Medical Campus, will be constructed just to the
northeast of the site. The pond has been designed to incorporate all necessary
detention, water quality, and L.I.D. (Low Impact Design) requirements for the north
portion (3.88 acres) of the Terra Vida 2 site. Please see the Banner Health Master
Drainage Exhibit provided in Appendix C. The portion of the Terra Vida 2 site that
was anticipated to drain to the “ODP Pond” is identified on this exhibit as “Basin 4”.
There will be 0.16 acres less than originally anticipated draining to the “ODP Pond”
from the Terra Vida 2 site.
3. The offsite storm sewer system in Precision Drive, which was recently constructed,
will receive and convey storm runoff from the south portion of the Terra Vida Site
(5.67 acres). Please see the Precision Drive Drainage Exhibit, provided in Appendix
D (excerpt from approved Final Drainage Report submitted as “Presidio Apartments”,
now referred to as “Terra Vida 1 Apartments”, Ref. 6). The portion of the Terra Vida
2 site that was anticipated to drain to the previously approved Precision Drive storm
sewer system is identified in this exhibit as “Basin 1”, “Basin 2”, and a portion of
“Basin 3”. There will be 0.13 acres more than originally anticipated draining to the
Precision Drive storm sewer system from the Terra Vida 2 site.
4. 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.
5. The drainage patterns anticipated for proposed drainage basins are described below.
Basins 1
Basin 1 will consist of apartment complex development. This basin will generally
drain via parking and drive curb and gutter to inlets and an internal storm drain
system. This system will tie to the offsite storm line system currently under review
with the Banner Health Medical Campus. This offsite storm system will convey runoff
to the offsite detention/water quality pond, referred to as the “ODP Pond”, currently
under review with the Banner Health Medical Campus, to be constructed just to the
northeast of the site.
Basin 2
Basin 2 rooftops and landscaped areas. This basin will generally drain via sheet flow
into the Lady Mood Drive R.O.W. Runoff will be collected in the existing Lady Mood
Drive storm sewer system.
Basin 3
Basin 1 will consist of apartment complex development. This basin will generally
drain via parking and drive curb and gutter to inlets and an internal storm drain
system. This system will tie to the offsite storm line system in Precision Drive, which
was recently constructed.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this report.
Terra Vida 2 Apartments
Preliminary Drainage Report 8
B. Specific Details
Standard water quality treatment will be provided in the offsite detention/water
quality pond, referred to as the “ODP Pond”, currently under review with the
Banner Health Medical Campus. This pond will be constructed just to the
northeast of the site. The pond has been designed to incorporate all necessary
detention, water quality, and L.I.D. (Low Impact Design) requirements for the
north portion (3.88 acres) of the Terra Vida 2 site.
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the proposed project complies with the City of Fort
Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with this project complies with all applicable City of
Fort Collins Master Drainage Plans.
3. The drainage plan and stormwater management measures proposed with the
proposed 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 any potential
damage associated with its stormwater runoff as all runoff is being captured and
routed to offsite drainage facilities which have either been previously approved by the
City of Fort Collins or are in the review and approval process with the City of Fort
Collins.
2. The drainage concept for the proposed development is consistent with all applicable
City of Fort Collins Master Drainage Plans.
Terra Vida 2 Apartments
Preliminary Drainage Report 9
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.
6. Final Drainage and Erosion Control Report for Presidio Apartments, Northern Engineering,
December 21, 2009.
APPENDIX A
HYDROLOGIC COMPUTATIONS
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: 514-002
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: ATC
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 Cf
= 1.00 100-year Cf = 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
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
1 169119 3.88 Note: For preliminary calculations, Composite Runoff Coefficients are 0.95 0.95 1.00 90%
2 26311 0.60 based on Table RO-10. 0.95 0.95 1.00 90%
3 247016 5.67 Composite % Imperviousness has been estimated based 0.95 0.95 1.00 90%
on UDFCD USDCM, Vol. I, Figures RO-3 and RO-4.
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
August 14, 2013
Overland Flow, Time of Concentration:
Project: 514-002
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = Ti + Tt (Equation RO-2)
Velocity (Gutter Flow), V = 20·S½
Velocity (Swale Flow), V = 15·S½
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)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Tc
Rational Method Equation: Project: 514-002
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 3.88 18 18 17 0.95 0.95 1.00 1.70 2.90 6.10 6.3 10.7 23.7
2 2 0.60 15 15 14 0.95 0.95 1.00 1.90 3.24 6.82 1.1 1.9 4.1
3 3 5.67 16 16 15 0.95 0.95 1.00 1.84 3.14 6.62 9.9 16.9 37.5
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)
ATC
August 14, 2013
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
APPENDIX B
WATER EROSION CONTROL REPORT
Terra Vida 2 Apartments
Preliminary Erosion Control Report
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 existing and 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 the Utility Plans. The Final Plans will contain a
full-size Erosion Control sheet 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 the Development Agreement for the development. 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, prior to any earth disturbance 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.
APPENDIX C
BANNER HEALTH MEDICAL CAMPUS MASTER DRAINAGE EXHIBIT
PRIVATE DR.
RD
RD
TF
E E E E E E E E E E E E E
E
G G G G G G G G G G
G
G
G G
G
G
G
G
G
G
G
G G G G G G G G G G G G
G G G G G G G G
E
E E
E
E
E
E
E
E
E
TF
RD
RD
RD
RD
H
Y
D
H
Y
D
H
Y
D
H
Y
D
G
G
T S
T S
F
E
S
H
Y
D
H
Y
D
H
Y
APPENDIX D
PRECISION DRIVE DRAINAGE PLAN
S
D
D
S
D
D
S
ELEC
S
WV
WV WV
WV
WV
H
Y
D
D
S
WV
WV
ELEC
V.S P.
S
S
S
S V.P.
V.P.S V.P.
V.P.
V.P.
S
V.P.
S V.P.
S
S
S
V.P.
H2O
S
H
Y
D
ELEC
S
X
VAULT
ELEC
VAULT
ELEC
VAULT
CABLE
V.P.
X
X
ELEC
VAULT
ELEC
WV
WV
S
S
Presidio Apartments
Final Drainage and Erosion Control Report
Character of Surface
Runoff
Coefficient
Percentage
Imperviousness
Streets, Parking Lots, RoofS, Alleys, and Drives:
Asphalt ……....……...…...…...………………………………………….. 0.95 100 Project: Presidio
Concrete …….......…….……………….………………………………… 0.95 90 Date: 6.30.09
Gravel ……….………….………………………………………………….. 0.50 40 By: ATC
Roofs …….…….………………………………………………………….. 0.95 90
Lawns and Landscaping
Sandy Soil ……..………………………………………………………….. 0.15 0
Clayey Soil ….….……….…………………………………………………. 0.25 0 2-year Cf
= 1.00 100-year Cf = 1.25
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3
Basin ID
Basin Area
(s.f.)
Basin Area
(acres)
Area of Asphalt
Streets, Parking
Lots, and Alleys
(sf)
Area of Roofs,
Walks,
and Driveways
(sf)
Area of Gravel
Parking
and Drives
(sf)
Area of Lawn
and Landscape
(sf)
2-year
Composite Runoff
Coefficient
100-year
Composite Runoff
Coefficient
Composite
%
Impervious
1 107523 2.468 91395 0 0 16128 0.85 1.00 85.00
2 102980 2.364 87533 0 0 15447 0.85 1.00 85.00
3 131838 3.027 112062 0 0 19776 0.85 1.00 85.00
4 97916 2.248 83229 0 0 14687 0.85 1.00 85.00
5 27956 0.642 17036 0 0 10920 0.68 0.85 60.94
1-5 468213 10.74869146 391254.45 0 0 76959 0.83 1.00 83.56
NOTE: all impervious surfaces within street, whether asphalt or concrete, have been grouped together in the "Asphalt" column
DEVELOPED COND. COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Presidio Apartments
Final Drainage and Erosion Control Report
Fort Collins, Colorado
Overland Flow, Time of Concentration:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = T
i + Tt
(Equation RO-2)
Intensity, i From Figures 3.3.1-2 (Area II) Project: Presidio
Velocity (Gutter Flow), V = 20·S
½
Date: 6.30.09
Velocity (Swale Flow), V = 15·S
½
By: ATC
Rational Equation: Q = CiA (Equation RO-1)
Time of Concentration
C*Cf
Length, L
(ft)
Slope, S
(%)
Ti
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(ft/s)
Tt
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(ft/s)
Tt
(min)
2-YR
Tc
(min)
110.25 50 2.0 8.9 400 1.0 2.00 3.3 0 0.0 0.00 N/A 12.3
220.25 50 2.0 8.7 350 1.0 2.00 2.9 0 0.0 0.00 N/A 11.7
330.25 50 2.0 8.7 450 1.0 2.00 3.8 0 0.0 0.00 N/A 12.5
440.25 50 2.0 8.7 475 1.0 2.00 4.0 0 0.0 0.00 N/A 12.7
550.25 20 2.0 5.5 780 0.7 1.67 7.8 0 0.0 0.00 N/A 13.3
DEVELOPED CONDITIONS 2-YR TIME OF CONCENTRATION COMPUTATIONS
Overland Flow Gutter Flow Swale Flow
Design
Point Basin(s)
(Equation RO-4)
()
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
Presidio Apartments
Final Drainage and Erosion Control Report
Fort Collins, Colorado
Overland Flow, Time of Concentration:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = T
i + Tt
(Equation RO-2)
Intensity, i From Figures 3.3.1-2 (Area II) Project: Presidio
Velocity (Gutter Flow), V = 20·S
½
Date: 6.30.09
Velocity (Swale Flow), V = 15·S
½
By: ATC
Rational Equation: Q = CiA (Equation RO-1)
Time of Concentration
C*Cf
Length, L
(ft)
Slope, S
(%)
Ti
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(ft/s)
Tt
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(ft/s)
Tt
(min)
100-YR
Tc
(min)
110.31 50 2.0 8.3 400 1.0 2.00 3.3 0 0.0 0.00 N/A 11.6
220.31 50 2.0 8.1 350 1.0 2.00 2.9 0 0.0 0.00 N/A 11.0
330.31 50 2.0 8.1 450 1.0 2.00 3.8 0 0.0 0.00 N/A 11.9
440.31 50 2.0 8.1 475 1.0 2.00 4.0 0 0.0 0.00 N/A 12.1
550.31 20 2.0 5.1 780 0.7 1.67 7.8 0 0.0 0.00 N/A 12.9
DEVELOPED CONDITIONS 100-YR TIME OF CONCENTRATION COMPUTATIONS
Overland Flow Gutter Flow Swale Flow
Design
Point Basin(s)
(Equation RO-4)
()
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
Presidio Apartments
Final Drainage and Erosion Control Report
Project: Presidio
Date: 6.30.09
By: ATC
1 1 2.47 12.3 11.6 0.85 1.00 2.05 7.29 4.3 18.0
2 2 2.36 11.7 11.0 0.85 1.00 2.09 7.42 4.2 17.5
3 3 3.03 12.5 11.9 0.85 1.00 2.05 7.29 5.2 22.1
4 4 2.25 12.7 12.1 0.85 1.00 2.02 7.16 3.8 16.1
5 5 0.64 13.3 12.9 0.68 0.85 1.98 7.04 0.9 3.8
DEVELOPED CONDITIONS DEVELOPED DIRECT RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
Basin(s) (cfs)
Area, A
(acres)
Intensity,
I100
(in/hr)
2-yr Tc
(min)
Intensity, I2
C2 (in/hr)
100-yr Tc
(min)
MAP POCKET
DRAINAGE EXHIBITS
D
D
G
G G
G
T
T T T
T
ST ST ST ST ST ST ST ST
ST ST ST ST ST ST ST ST
ST
ST ST ST
ST
�
�
GM
GM
GM
HC
HC
VAN
HC
HC
TF
TF
TF
TF
TF
TF
TF
TF
TF
TF
TF
HC
GARAGE
G8
GARAGE
G9
GARAGE
G13
GARAGE
G15
GARAGE
G16
GARAGE
G12
GARAGE
G11
GARAGE G17
LE FEVER DRIVE
(76' ROW)
CINQUEFOIL LANE
(82' ROW)
PRECISION DRIVE
(51' ROW)
LADY MOON DRIVE
(84' ROW)
GARAGE
G1
BLDG 1
BLDG 2
BLDG 3
BLDG 4
BLDG 8
BLDG 7
BLDG 10
(4 LIVE/WORK
UNITS)
BLDG 9
BLDG 5
BLDG 6
GARAGE G14
GARAGE G10
3
5.67 ac
1
3.88 ac
2
0.60 ac
1
3
2
4.5' SIDEWALK
5' SIDEWALK
5' SIDEWALK
6' SIDEWALK
No. Revisions:
By: Date:
REVIEWED BY:
N. Haws
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
Sept. 4, 2013
PROJECT:
514-002
Sheet
Of 6 Sheets
TERRA VIDA II APARTMENTS
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NOT FOR CONSTRUCTION
REVIEW SET
09/04/13
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C400
DRAINAGE EXHIBIT
A. Cvar
N. Whitcomb
1"=40'
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
City Engineer Date
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer Date
APPROVED:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
Water & Wastewater Utility
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
NORTH
( IN FEET )
1 inch = ft.
40 0 40 Feet
40
80 120
LEGEND:
4953
PROPOSED CONTOUR 93
PROPOSED STORM SEWER
PROPOSED SWALE
EXISTING CONTOUR
PROPOSED PROPERTY BOUNDARY CURB & GUTTER
PROPOSED INLET
1
DESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
PROPOSED SWALE SECTION
1 1
PROJECT BENCHMARK
BENCHMARK #1:
City of Fort Collins Benchmark 7-01
Elevation = 4911.33
BENCHMARK #2:
City of Fort Collins Benchmark 7-07
Elevation = 4975.97
NOTES:
1.REFER TO THE "PRELIMINARY DRAINAGE REPORT FOR TERRA VIDA II APARTMENTS" BY NORTHERN
ENGINEERING, DATED {SEPTEMBER 4, 2013} FOR ADDITIONAL INFORMATION.{
}
BASIN
DESIGNATION
BASIN
AREA (AC)
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
PROPOSED UNDERDRAIN UD
1
X.XXX
−
=
}
−
=
}
WV
WV
D
V.P. V.P.
V.P.
S
WV
WV
S
D
X
X
X
X
X
W
S
O
X
V.P.
X
X
W
S
O
S
D
D D
S
D
D
SSANI
SANI
SANI
D
D D
S
VAULT
ELEC
WV
WV
WV
S
VAULT
ELEC
E
E
E
E
VAULT
ELEC
E
E
E
E
E
W
8" W
H
Y
D
WV
WV
8" W
8" W
8" W
H
Y
D
WV
WV
WV
WV
WV
W
WV
WV
8" W
WV
WV
12" W
FO
FO
FO
FO
FO
FO
FO
CABLE
ELEC
T
T
T
T
T
G
G
G
G
G
GAS
T
T
T
T
T
T
T
T
T
TELE
H2O
GAS
GAS
VAULT
ELEC
VAULT
ELEC ELEC
E
D
F
E
S
F
E
S
D
VAULT
ELEC
V.P.
W
V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
ST ST
D
ST ST ST
ST
ST
ST ST
ST ST
10" SS 10" SS
10" SS 10" SS
10" SS
8" SS
12" SS
SS
18" SS
8" SS
12" SS
18" SS
8" SS
8" SS
SS
D D
W
12" W 12" W
6" W
12" W 12" W
8" W
R R
R R
R
R
R
R R
ST
10
12
14
10
8
22
12
10
24
11
11
22
24
24
24
24
8
6
12
HC
HC
HC
9
14 14
10
14
13
6
HC
HC
7
HC
11
HC
HC
HC
HC
4
12 5
8
18
GM
GM
GM
GM
GM
GM
GM
GM
GM
GM
EM
EM
EM
EM
EM
EM
EM
EM
EM
EM
TF
TF
TF
TF
TF
TF
TF
TF
TF
4
TF
TF
1
2
3
4
5
Drawn by:ATC Date Drawn:7.15.09
NORTH
0
1 inch ( = IN ft. PRESIDIO
FUTURE PRECISION DRIVE DRAINAGE BASINS
D
GAS
GAS
F
E
S
F
E
S
F
E
S
F
E
S
F
E
S
F
E
S
F
E
S
�
�
D
D
D
D
D
D
D
D D
D
D
D D
LOT ONE
HARMONY
TECHNOLOGY
PARK, SECOND
FILING
LOT TWO
HARMONY
TECHNOLOGY
PARK, SECOND
FILING
LOT TWO
HARMONY
TECHNOLOGY
PARK, SECOND
FILING
PRECISION
DRIVE
OWNER:
ANDERSON, KATHRYN JOY
WINCHESTER, ELSIE A / SUSAN P
BILL RAY II / LUCAS, SHERI W
OWNER:
CHANDLER, J THOMAS
OWNER:
CHANDLER, J THOMAS
TRACT E
BROOKFIELD
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H
Y
D
F
E
S
F
E
S
V.P.
V.P.V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
V.P.
F
E
S
F
E
S
C.O.
LID
LID
PROPOSED STORM LINE
PROPOSED STORM LINE
PROPOSED STORM LINE
TOTAL VOLUME~2.61 AC-FT
POND AREA~38,288 SF / 0.90 ACRES
100 YR. RELEASE RATE 39.7 CFS
TOTAL VOLUME~3.92 AC-FT
SURFACE AREA 48,207 SF / 1.10 AC
100 YR. RELEASE RATE 0.7 CFS
TRACT i
100 YR. RELEASE RATE 25.1 CFS
TRACT M
100 YR. RELEASE RATE 29.1 CFS
FOSSIL CREEK RESERVOIR INLET DITCH
IRRIGATION DITCH ACCESS ROAD
PROPOSED PLD SECTION
WITH UNDERDRAIN
3
23.79
1
13.88
2
13.00
4
5.10
5
5.90
TOTAL VOLUME~8.39 AC-FT
POND AREA~120,166 SF / 2.76 ACRES
100 YR. RELEASE RATE 28.2 CFS
TRACT K
HARMONY ROAD
LADY MOON DR.
CINQUEFOIL LANE
LE FEVER DR.
UEFOIL LANE
LADY MOON DR.
TIMBERWOOD
DR.
CINQUEFOIL LANE
NORTH
( IN FEET )
1 inch = ft.
100 0 100 Feet
100
200 300
LEGEND:
5013
PROPOSED CONTOUR 93
EXISTING STORM SEWER
PROPOSED STORM SEWER
ST
PROPOSED SWALE
EXISTING CONTOUR
PROPOSED VERTICAL
PROJECT BOUNDARY
PROPOSED SPOT ELEVATION 33.43
PROPOSED SLOPES
PROPOSED STORM INLET
2.0%
PEDESTRIAN ACCESS RAMPS
EXISTING SPOT ELEVATION (47.45)
CURB & GUTTER
PROPOSED FIRE HYDRANT
PROPOSED ELECTRIC TRANSFORMER
LOT LINE
PROPOSED CONCRETE
CROSS PAN (TYP.)
KEYMAP
HARMONY ROAD
BROOKFIELD DRIVE
LE FEVER DRIVE
TIMBERWOOD DRIVE
LADY MOON DR.
CINQUEFOIL LANE
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
K��� ����'� �����.
C��� ������ ��� ���.
R
Date
Date
Date
Date
Date
Date
APPROVED:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
City Engineer
Water & Wastewater Utility
Stormwater Utility
Parks & Recreation
Traffic Engineer
Environmental Planner
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
EXHIBIT
MASTER DRAINAGE
�600
FOR DRAINAGE REVIEW ONLY.
NOT FOR CONSTRUCTION.
���� �������, ��������
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NOT FOR CONSTRUCTION
REVIEW SET
��56
����� ����
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
11No0.25 0.25 0.32 45 1.00% 10.7 10.7 9.8 634 0.50% 1.41 7.5 N/A N/A 18 18 17
22No0.25 0.25 0.32 60 1.00% 12.3 12.3 11.3 220
0.50% 1.41 2.6 N/A N/A 15 15 14
33No0.25 0.25 0.32 45 1.00% 10.7 10.7 9.8 420
0.50% 1.41 4.9 N/A N/A 16 16 15
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point
Basin
Overland Flow
ATC
August 14, 2013
Time of Concentration
(Equation RO-4)
3
1
1 . 87 1 . 1 *
S
Ti C Cf L