HomeMy WebLinkAboutWATERFIELD FOURTH FILING - MAJOR AMENDMENT / PDP - PDP180009 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTJuly 18, 2018
PRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT FOR
THRIVE
Fort Collins, Colorado
Prepared for:
Risheill Homes, LLC
P.O. Box 400
Castle Rock, CO 80104
Prepared by:
301 N. Howes, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 1496-001
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.
July 18, 2018
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage and Erosion Control Report for
THRIVE
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 Thrive 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, PhD, PE
Senior Project Engineer
Thrive
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 1
C. Floodplain.......................................................................................................................................... 4
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4
A. Major Basin Description .................................................................................................................... 4
B. Sub-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
F. Modifications of Criteria ................................................................................................................... 7
IV. DRAINAGE FACILITY DESIGN .................................................................................... 7
A. General Concept ............................................................................................................................... 7
B. Specific Details .................................................................................................................................. 7
V. CONCLUSIONS ........................................................................................................ 9
A. Compliance with Standards .............................................................................................................. 9
B. Drainage Concept .............................................................................................................................. 9
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – USDA Soils Information
APPENDIX C – SWMM Modeling; Detention Computations
APPENDIX D – LID Information; Water Quality Capture Volume Computations
APPENDIX E – Erosion Control Report
Thrive
Preliminary Drainage Report
LIST OF FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2– Proposed Site Plan ................................................................................................ 3
Figure 3 – Existing Floodplains ............................................................................................. 4
MAP POCKET:
Proposed Drainage Exhibit
Thrive
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. The project site is located in the west half of Section 5, Township 7 North, Range 68
West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of
Colorado.
3. The project site is located on the north side of Vine Drive and is just northwest of the
intersection of Vine Drive and Timberline Road.
4. The project site lies within the Dry Creek Basin. Detention requirements are to detain
the difference between the 100-year developed inflow rate and the historic 2-year
release rate. The historic release rate for this basin is 0.20 cfs per acre.
5. The existing Waterfield P.U.D. First Filing residential development exists to the
southeast of the proposed Third Filing site. The Lake Canal crosses the southwest
corner of the property, and is within the property limits. The Larimer and Weld Canal
runs along the northern border of the property.
6. Any offsite flows that would enter the site on the north are intercepted by the Larimer
and Weld Canal. Offsite flows from the adjacent Waterfield P.U.D. First Filing site
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Preliminary Drainage Report 2
was planned to be detained within the current project southern detention pond. The
current design of the southern detention pond accounts for this area (17.40 Acres) in
detention modeling, as discussed below.
B. Description of Property
1. The development area is roughly 78.9 net acres.
Figure 1 – Aerial Photograph
2. The subject property is currently leased for farming purposes. The ground cover
generally consists of row crops. Existing ground slopes are mild to moderate (i.e., 1 -
6±%) through the interior of the property. General topography slopes from north to
south. The existing wetland area within the interior of the site collects a significant
amount of storm drainage and excess irrigation flows.
3. There is an existing detention pond located along the southern boundary of the project
site, which has been utilized for detention of the adjacent Waterfield P.U.D. First
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Preliminary Drainage Report 3
Filing site. The current design maintains detention for the Waterfield P.U.D. First
Filing site and expands upon this pond for the proposed additional area to be directed
to the pond.
4. 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 primarily consists
of Nunn Clay loam and Satanta Loam, both of which fall into Hydrologic Soil Group C.
5. The proposed project site plan is composed of single-family and multi-family
residential development. Associated roadways, water and sewer lines will be
constructed with the development. The existing wetland within the interior of the site
be utilized for stacked detention (detention over the permanent pool elevation of the
wetland). The existing detention pond constructed with Waterfield P.U.D. First Filing,
located along the south boundary of the site, will be expanded and utilized for
detention and water quality treatment.
Figure 2– Proposed Site Plan
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Preliminary Drainage Report 4
6. The Lake Canal crosses the southwest corner of the property; the Larimer and Weld
Canal runs along the northern border of the property.
7. The proposed land use is residential and commercial.
C. Floodplain
1. The project site is not encroached by any City designated or FEMA designated 100-
year floodplain.
Figure 3 –Area Floodplain Mapping
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site lies within the Dry Creek Basin. Detention requirements are to detain
the difference between the 100-year developed inflow rate and the historic 2-year
release rate. The historic release rate for this basin is 0.20 cfs per acre. The site
outfall is the existing outfall structure for the existing detention pond constructed with
Waterfield P.U.D., First Filing. The outfall for this pond is a siphon storm line
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Preliminary Drainage Report 5
which conveys flows under the Lake Canal. This pond is to be modified with
the currently proposed development to incorporate detention and water quality
measures for the existing development, as well as the proposed Waterfield
Third Filing development. It is understood that the siphon outfall for this pond
is the responsibility of the development to maintain.
B. Sub-Basin Description
1. The subject property historically drains overland from north to south. Runoff from a
portion of the site has historically collected in the existing wetland located within the
interior of the site. The remainder of the site historically sheet flows to the existing
detention pond at the southern boundary of the site. This pond outfalls via a siphon
under the Lake Canal into the Vine Drive roadside ditch. The proposed site will
generally maintain these historic drainage patterns. A more detailed description of the
project drainage patterns is provided below.
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 detention and LID treatment 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 treatment, where none previously
existed, sediment with erosion potential is removed from downstream drainageway
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Preliminary Drainage Report 6
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:
The proposed development will provide LID and water quality treatment; thus,
eliminating sources of potential pollution previously left exposed to weathering and
runoff processes.
C. Development Criteria Reference and Constraints
The subject property is surrounded by currently developed properties. 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, the subject property is not located in a City designated floodplain.
The proposed project does not propose to modify any natural drainageways.
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Preliminary Drainage Report 7
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.
2. The existing wetland within the interior of the site be utilized for stacked detention
(detention over the permanent pool elevation of the wetland). The existing detention
pond constructed with Waterfield P.U.D. First Filing, located along the south
boundary of the site, will be expanded and utilized for detention and water quality
treatment.
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. The drainage patterns anticipated for proposed drainage basins are described below.
Basins 1 through 5
Basins 1 through 5 consist of open space, single-family residential and multi-family
residential development. These basins will drain generally via street curb and gutter to
onsite storm inlets and storm line system, which will direct runoff into a series of
raingardens. LID treatment will occur within proposed raingardens, the ultimate
discharge point from the raingardens will be the the existing wetland detention pond
located within the central western portion of the site. The existing wetland will be
utilized for water quality capture volume and detention over the permanent water
surface of the wetland area, as discussed below.
Basin 6
Basin 6 consists of open space and the existing wetland area. Basin 6 has been
included in computation of required detention volume, but not in computation of
required water quality capture volume.
Basin 7
Basin 7 consists of the northern half of the Right of Way of Suniga Drive. LID
treatment for this basin will occur within a proposed raingarden, which will discharge
into the existing wetland detention pond. The existing wetland will be utilized for
water quality capture volume and detention over the permanent water surface of the
wetland area, as discussed below.
Basins 8 and 9
Basins 8 and 9 consist of open space, single-family residential and multi-family
residential development. These basins will drain generally via street curb and gutter to
onsite storm inlets and storm line system, which will direct runoff into proposed Pond
1 and Pond 2, located at the southern boundary of the site. Water quality capture
volume will be provided in the lower stage of Pond 1, as discussed below.
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Preliminary Drainage Report 8
Basins OS1 and OS2
Basins OS1 and OS2 consists of the adjacent half streets of Vine Drive and Timberline
Road. Basin OS1 will be conveyed into the existing wetland pond, Basin OS2 will be
conveyed into proposed Pond 1. We have included these basins in water quality
capture volume computations and detention computations for the proposed ponds.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this report.
B. Specific Details
1. Standard water quality treatment in the form of Extended Detention is being
provided for the proposed development in Pond 3.
2. Water Quality Capture Volume for the northern portion of the site (Basins 1
through 5, 7, OS 1) will be provided in the lower stage of the wetland
detention pond. These basins comprise 49.8 acres. We will treat 50% of this
area (24.9 acres) with extended detention, and have calculated a required
volume of 0.48 acre-feet. The wetland detention pond will provide water
quality treatment in the wet component of this pond. As previously discussed,
this pond is an existing wetland with a permanent water surface. The wetland
vegetation and permanent pool will greatly enhance water quality for runoff
discharging from the site. Raingardens will be provided for pre-treatment for
the majority of developed runoff prior to entry to the existing wetland.
3. Water Quality Capture Volume for the southern portion of the site (Basins 8, 9,
OS2) will be provided in the lower stage of Pond 1. These basins comprise
32.0 acres. We will treat 50% of this area (16.0 acres) with extended
detention, and have calculated a required volume of 0.27 acre-feet.
4. Please see Water Quality Capture Volume (Extended Detention) computations
provided in Appendix D.
5. Onsite LID requirements will be met with the provision of raingardens
throughout basins 1 through 5 and basin 7. These raingardens will meet or
exceed a treatment area of 50% of the overall developed site area. Please see
LID information and computations as well as an LID Exhibit provided in
Appendix D.
6. Please see Table 1, below, for a summary of detention and Water Quality
Capture volume requirements.
Table 1 - SWMM Modeling Output and Extended Detention Volume Summary
Pond ID Vol. (Ac-Ft)
100-Yr
WSEL
(Ft)
WQ Capture
Vol. (Ac-Ft)
WQ WSEL
(Ft)
Total Req'd
Vol. (Ac-Ft)
100-Yr
Release
(cfs)
Wetland 12.16 TBD 0.48 TBD 12.64 3.20
1 7.46 TBD 0.27 TBD 7.73 7.6
2 4.87 TBD N/A TBD 4.87 13.2
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Preliminary Drainage Report 9
7. Final design details, and construction documentation shall be provided to the
City of Fort Collins for review prior to Final Development Plan approval.
8. Stormwater facility Standard Operating Procedures (SOP) will be provided by
the City of Fort Collins in the Development Agreement.
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 requirements for Dry
Creek Basin.
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 by providing detention and water
quality mitigation features.
2. The drainage concept for the proposed development is consistent with requirements
for the Dry Creek Basin.
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Preliminary Drainage Report 10
References
1. 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.
2. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
4. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
5. Final Drainage Report for Waterfield P.U.D. First Filing, Northern Engineering, October 20,
1998.
Fossil Creek 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 A
Hydrologic Computations
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: 1496-001
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…………………………...………………..…………………………………………….. 0.50 40%
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
Lawn, Rain
Garden, or
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
1 507193 11.64 3.49 0.58 1.40 0.00 6.17 0.58 0.58 0.72 45%
2 168223 3.86 1.16 0.19 0.46 0.00 2.05 0.58 0.58 0.72 45%
3 139990 3.21 0.96 0.16 0.39 0.00 1.70 0.58 0.58 0.72 45%
4 465370 10.68 3.21 0.53 1.28 0.00 5.66 0.58 0.58 0.72 45%
5 663704 15.24 4.57 0.76 1.83 0.00 8.08 0.58 0.58 0.72 45%
6 479098 11.00 0.00 0.00 0.00 0.00 11.00 0.25 0.25 0.31 0%
7 150213 3.45 1.90 0.34 0.00 0.00 1.21 0.71 0.71 0.88 64%
8 629464 14.45 2.89 0.72 1.73 0.00 9.10 0.51 0.51 0.64 35%
9 714312 16.40 3.28 0.82 1.97 0.00 10.33 0.51 0.51 0.64 35%
Overland Flow, Time of Concentration:
Project: 1496-001
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = T
i + 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)
Slope,
S
(%)
Velocity,
V
(ft/s)
Rational Method Equation: Project: 1496-001
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 11.64 20 20 19 0.58 0.58 0.72 1.61 2.74 5.75 10.85 18.47 48.46
2 2 3.86 18 18 18 0.58 0.58 0.72 1.70 2.90 6.01 3.80 6.48 16.80
3 3 3.21 18 18 17 0.58 0.58 0.72 1.73 2.95 6.20 3.21 5.48 14.42
4 4 10.68 25 25 25 0.58 0.58 0.72 1.43 2.44 5.04 8.85 15.09 38.93
5 5 15.24 20 20 20 0.58 0.58 0.72 1.61 2.74 5.68 14.20 24.17 62.58
6 6 11.00 28 28 26 0.25 0.25 0.31 1.36 2.32 4.93 3.73 6.37 16.93
7 7 3.45 30 30 30 0.71 0.71 0.88 1.30 2.21 4.56 3.16 5.37 13.86
8 8 14.45 24 24 23 0.51 0.51 0.64 1.48 2.52 5.20 10.85 18.54 47.81
9 9 16.40 22 22 21 0.51 0.51 0.64 1.53 2.61 5.46 12.77 21.79 56.97
OS1 OS1 1.68 17 17 17 0.71 0.71 0.88 1.75 2.99 6.20 2.08 3.56 9.22
OS2 OS2 1.12 21 21 20 0.73 0.73 0.91 1.56 2.67 5.60 1.27 2.18 5.71
Historic Site Historic Site 92.74 46 46 44 0.25 0.25 0.31 0.98 1.67 3.51 22.86 38.95 102.34
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
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
7/15/2018
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
USDA Soils Information
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Larimer County
Natural Area, Colorado
Resources
Conservation
Service
July 12, 2018
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface.................................................................................................................... 2
How Soil Surveys Are Made..................................................................................5
Soil Map.................................................................................................................. 8
Soil Map................................................................................................................9
Legend................................................................................................................10
Map Unit Legend................................................................................................ 11
Map Unit Descriptions.........................................................................................11
Larimer County Area, Colorado...................................................................... 13
73—Nunn clay loam, 0 to 1 percent slopes.................................................13
References............................................................................................................15
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
Custom Soil Resource Report
6
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
8
9
Custom Soil Resource Report
Soil Map
4488910 4488940 4488970 4489000 4489030 4489060 4489090
4488910 4488940 4488970 4489000 4489030 4489060 4489090
493200 493230 493260 493290 493320 493350 493380 493410 493440 493470 493500
493200 493230 493260 493290 493320 493350 493380 493410 493440 493470 493500
40° 33' 9'' N
105° 4' 49'' W
40° 33' 9'' N
105° 4' 35'' W
40° 33' 3'' N
105° 4' 49'' W
40° 33' 3'' N
105° 4' 35'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 20 40 80 120
Meters
Map Scale: 1:1,430 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
73 Nunn clay loam, 0 to 1 percent
slopes
8.1 100.0%
Totals for Area of Interest 8.1 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
Custom Soil Resource Report
11
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
Custom Soil Resource Report
12
Larimer County Area, Colorado
73—Nunn clay loam, 0 to 1 percent slopes
Map Unit Setting
National map unit symbol: 2tlng
Elevation: 4,100 to 5,700 feet
Mean annual precipitation: 14 to 15 inches
Mean annual air temperature: 48 to 52 degrees F
Frost-free period: 135 to 152 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Nunn and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Nunn
Setting
Landform: Terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Pleistocene aged alluvium and/or eolian deposits
Typical profile
Ap - 0 to 6 inches: clay loam
Bt1 - 6 to 10 inches: clay loam
Bt2 - 10 to 26 inches: clay loam
Btk - 26 to 31 inches: clay loam
Bk1 - 31 to 47 inches: loam
Bk2 - 47 to 80 inches: loam
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately low to
moderately high (0.06 to 0.20 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 7 percent
Salinity, maximum in profile: Nonsaline (0.1 to 1.0 mmhos/cm)
Sodium adsorption ratio, maximum in profile: 0.5
Available water storage in profile: High (about 9.1 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: C
Ecological site: Clayey Plains (R067BY042CO)
Hydric soil rating: No
Custom Soil Resource Report
13
Minor Components
Heldt
Percent of map unit: 10 percent
Landform: Terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Ecological site: Clayey Plains (R067BY042CO)
Hydric soil rating: No
Wages
Percent of map unit: 5 percent
Landform: Terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across-slope shape: Linear
Ecological site: Loamy Plains (R067BY002CO)
Hydric soil rating: No
Custom Soil Resource Report
14
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/national/soils/?cid=nrcs142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuse/rangepasture/?cid=stelprdb1043084
15
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/soils/scientists/?cid=nrcs142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf
Custom Soil Resource Report
16
APPENDIX C
SWMM Modeling; Detention Computations
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.012)
--------------------------------------------------------------
*********************************************************
NOTE: The summary statistics displayed in this report are
based on results found at every computational time step,
not just on results from each reporting time step.
*********************************************************
****************
Analysis Options
****************
Flow Units ............... CFS
Process Models:
Rainfall/Runoff ........ YES
RDII ................... NO
Snowmelt ............... NO
Groundwater ............ NO
Flow Routing ........... YES
Ponding Allowed ........ NO
Water Quality .......... NO
Infiltration Method ...... HORTON
Flow Routing Method ...... KINWAVE
Starting Date ............ 11/21/2012 00:00:00
Ending Date .............. 11/22/2012 06:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 00:15:00
Wet Time Step ............ 00:05:00
Dry Time Step ............ 01:00:00
Routing Time Step ........ 30.00 sec
************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 33.674 3.669
Evaporation Loss ......... 0.000 0.000
Infiltration Loss ........ 10.773 1.174
Surface Runoff ........... 22.635 2.466
SWMM 5 Page 1
Final Storage ............ 0.388 0.042
Continuity Error (%) ..... -0.361
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 22.635 7.376
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 12.072 3.934
Flooding Loss ............ 0.000 0.000
Evaporation Loss ......... 0.000 0.000
Exfiltration Loss ........ 0.000 0.000
Initial Stored Volume .... 0.000 0.000
Final Stored Volume ...... 10.560 3.441
Continuity Error (%) ..... 0.013
********************************
Highest Flow Instability Indexes
********************************
All links are stable.
*************************
Routing Time Step Summary
*************************
Minimum Time Step : 30.00 sec
Average Time Step : 30.00 sec
Maximum Time Step : 30.00 sec
Percent in Steady State : 0.00
Average Iterations per Step : 1.00
Percent Not Converging : 0.00
***************************
Subcatchment Runoff Summary
***************************
SWMM 5 Page 2
--------------------------------------------------------------------------------------------------------
Total Total Total Total Total Total Peak Runoff
Precip Runon Evap Infil Runoff Runoff Runoff Coeff
Subcatchment in in in in in 10^6 gal CFS
--------------------------------------------------------------------------------------------------------
1 3.67 0.00 0.00 1.12 2.52 4.16 259.74 0.686
2 3.67 0.00 0.00 1.22 2.43 0.95 60.53 0.663
4(Waterfield_First_Filing) 3.67 0.00 0.00 1.15 2.48 1.17 71.27 0.677
3 3.67 0.00 0.00 1.35 2.30 1.09 64.47 0.626
******************
Node Depth Summary
******************
---------------------------------------------------------------------------------
Average Maximum Maximum Time of Max Reported
Depth Depth HGL Occurrence Max Depth
Node Type Feet Feet Feet days hr:min Feet
---------------------------------------------------------------------------------
outfall OUTFALL 0.00 0.00 96.00 0 00:00 0.00
WetlandPond STORAGE 1.04 1.30 106.30 0 03:03 1.30
pond1 STORAGE 2.67 3.27 103.27 0 08:25 3.27
pond2 STORAGE 0.80 3.76 105.76 0 02:16 3.76
*******************
Node Inflow Summary
*******************
-------------------------------------------------------------------------------------------------
Maximum Maximum Lateral Total Flow
Lateral Total Time of Max Inflow Inflow Balance
Inflow Inflow Occurrence Volume Volume Error
Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent
-------------------------------------------------------------------------------------------------
outfall OUTFALL 0.00 7.54 0 08:25 0 3.93 0.000
WetlandPond STORAGE 259.74 259.74 0 00:40 4.16 4.16 -0.002
pond1 STORAGE 60.53 67.75 0 00:40 0.954 5.04 -0.002
pond2 STORAGE 135.74 135.74 0 00:40 2.27 2.27 0.050
SWMM 5 Page 3
*********************
Node Flooding Summary
*********************
No nodes were flooded.
**********************
Storage Volume Summary
**********************
--------------------------------------------------------------------------------------------------
Average Avg Evap Exfil Maximum Max Time of Max Maximum
Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow
Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS
--------------------------------------------------------------------------------------------------
WetlandPond 402.681 2 0 0 529.739 3 0 03:02 3.19
pond1 223.898 7 0 0 324.935 10 0 08:25 7.54
pond2 33.096 2 0 0 212.310 14 0 02:15 13.17
***********************
Outfall Loading Summary
***********************
-----------------------------------------------------------
Flow Avg Max Total
Freq Flow Flow Volume
Outfall Node Pcnt CFS CFS 10^6 gal
-----------------------------------------------------------
outfall 99.42 4.90 7.54 3.933
-----------------------------------------------------------
System 99.42 4.90 7.54 3.933
********************
Link Flow Summary
********************
SWMM 5 Page 4
-----------------------------------------------------------------------------
Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence |Veloc| Full Full
Link Type CFS days hr:min ft/sec Flow Depth
-----------------------------------------------------------------------------
out1 DUMMY 3.19 0 03:03
out2 DUMMY 7.54 0 08:25
out3 DUMMY 13.17 0 02:16
*************************
Conduit Surcharge Summary
*************************
No conduits were surcharged.
Analysis begun on: Tue Jul 17 13:14:34 2018
Analysis ended on: Tue Jul 17 13:14:34 2018
Total elapsed time: < 1 sec
SWMM 5 Page 5
Link out1 Flow (CFS)
Elapsed Time (hours)
0 5 10 15 20 25 30 35
Flow (CFS)
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
SWMM 5 Page 1
Node pond1 Volume (ft3)
Elapsed Time (hours)
0 5 10 15 20 25 30 35
Volume (ft3)
350000.0
300000.0
250000.0
200000.0
150000.0
100000.0
50000.0
0.0
SWMM 5 Page 1
Link out2 Flow (CFS)
Elapsed Time (hours)
0 5 10 15 20 25 30 35
Flow (CFS)
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
SWMM 5 Page 1
Node pond2 Volume (ft3)
Elapsed Time (hours)
0 5 10 15 20 25 30 35
Volume (ft3)
250000.0
200000.0
150000.0
100000.0
50000.0
0.0
SWMM 5 Page 1
Link out_wetland Flow (CFS)
Elapsed Time (hours)
0 5 10 15 20 25 30 35
Flow (CFS)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
SWMM 5 Page 1
Node WetlandPond Volume (ft3)
Elapsed Time (hours)
0 5 10 15 20 25 30 35
Volume (ft3)
600000.0
500000.0
400000.0
300000.0
200000.0
100000.0
0.0
SWMM 5 Page 1
Project: 1496-001
By: ATC
Date: 7/11/2018
Note: Volume calculations utilize Conic Method
Pond Stage Depth Surface Area Incremental Total Volume Total Volume
of Contour Volume
(FT) (SF) (CF) (CF) (AF)
48 0 820 0 0 0.000
49 1.00 91256 33542 33542 0.770
50 1.00 191306 138092 171634 3.940
51 1.00 305971 246159 417792 9.591
52 1.00 456043 378141 795934 18.272
52.5 0.50 610317 265389 1061323 24.365
Pond Volume Calculations
Pond Stage-Storage Curve
Pond: 1
By: ATC
Date: 7/15/18
Stage
(FT)
Contour Area
(SF)
Volume
(CU.FT.)
Volume
(AC-FT)
4,941.200 45.93 0.00 0.00
4,941.400 1,236.20 101.36 0.00
4,941.600 4,037.56 601.89 0.01
4,941.800 8,450.01 1823.79 0.04
4,942.000 14,473.55 4089.29 0.09
4,942.200 22,108.19 7720.62 0.18
4,942.400 31,484.88 13052.37 0.30
4,942.600 41,051.30 20284.87 0.47
4,942.800 49,272.82 29304.78 0.67
4,943.000 57,158.05 39938.12 0.92
4,943.200 64,787.25 52124.68 1.20
4,943.400 72,291.66 65825.72 1.51
4,943.600 79,678.81 81016.78 1.86
4,943.800 86,948.70 97674.24 2.24
4,944.000 94,101.32 115774.53 2.66
4,944.200 96,520.43 134836.20 3.10
4,944.400 98,023.50 154290.40 3.54
4,944.600 99,526.94 174045.25 4.00
4,944.800 101,030.76 194100.83 4.46
4,945.000 102,534.95 214457.22 4.92
4,945.200 104,039.51 235114.48 5.40
4,945.400 105,544.45 256072.70 5.88
4,945.600 107,049.76 277331.94 6.37
4,945.800 108,555.45 298892.29 6.86
4,946.000 110,061.51 320753.81 7.36
4,946.200 111,567.95 342916.58 7.87
4,946.400 113,074.75 365380.69 8.39
4,946.600 114,581.93 388146.19 8.91
4,946.800 116,089.49 411213.17 9.44
4,947.000 117,597.42 434581.69 9.98
4,947.200 119,105.72 458251.85 10.52
Pond Stage-Storage Curve
Pond: 2
By: ATC
Date: 7/15/18
Stage
(FT)
Contour Area
(SF)
Volume
(CU.FT.)
Volume
(AC-FT)
4,944.800 906.53 0.00 0.00
4,945.000 4,050.76 458.24 0.01
4,945.200 9,161.62 1745.19 0.04
4,945.400 15,839.80 4215.05 0.10
4,945.600 22,573.87 8036.59 0.18
4,945.800 29,217.77 13201.49 0.30
4,946.000 35,771.51 19689.37 0.45
4,946.200 42,235.07 27481.09 0.63
4,946.400 48,608.47 36557.98 0.84
4,946.600 54,891.71 46901.64 1.08
4,946.800 61,070.05 58492.32 1.34
4,947.000 67,116.11 71306.18 1.64
4,947.200 69,183.08 84935.58 1.95
4,947.400 70,129.37 98866.72 2.27
4,947.600 71,080.11 112987.56 2.59
4,947.800 72,035.32 127299.00 2.92
4,948.000 72,994.98 141801.92 3.26
4,948.200 73,959.09 156497.22 3.59
4,948.400 74,927.67 171385.79 3.93
4,948.600 75,900.70 186468.52 4.28
4,948.800 76,878.18 201746.31 4.63
4,949.000 77,860.13 217220.03 4.99
4,949.200 78,846.52 232890.59 5.35
4,949.400 79,837.38 248758.88 5.71
APPENDIX D
LID Information; Water Quality Capture Volume Computations
WATER QUALITY POND DESIGN CALCULATIONS
Extended Detention (Lower Stage Wetland Pond)
Project: 1496-001
By: ATC
Date: 7/15/18
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 24.900 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 45.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.4500 <-- CALCULATED
WQCV (watershed inches) = 0.193 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.480 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in2) = ** <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = ** <-- INPUT from Figure 5
n = ** <-- INPUT from Figure 5
t (in) = ** <-- INPUT from Figure 5
number of rows = ** <-- CALCULATED from WQ Depth and row spacing
**To be completed at final design
WATER QUALITY POND DESIGN CALCULATIONS
Extended Detention (Lower Stage Pond 1)
Project: 1496-001
By: ATC
Date: 7/15/18
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 16.000 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 35.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.3500 <-- CALCULATED
WQCV (watershed inches) = 0.166 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.266 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in2) = ** <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = ** <-- INPUT from Figure 5
n = ** <-- INPUT from Figure 5
t (in) = ** <-- INPUT from Figure 5
number of rows = ** <-- CALCULATED from WQ Depth and row spacing
**To be completed at final design
Project: 1496-001
By: ATC
Date: 7/11/18
LID ID Basin (s) Total Basin (s)
Area (Ac.)
LID Raingarden Req'd Min.
Volume (Cu.-Ft.)
R1 - R3 1, 2 15.51 8691
R4a - R4b 4 10.68 5984
R5 - R7 3,5 18.45 10338
R8 7 3.45 1933
Total Newly Developed Area: 78.90 Ac.
Total Area Treated: 44.80 Ac.
Percent of New Impervious Area Treated: 56.78%
On-Site Treatment by LID Summary Table
UD
UD
UD
IRR
IRR
IRR
IRR
IRR
IRR IRR IRR
IRR IRR
UD
STREET A
STREET B
STREET C
STREET C
STREET D
STREET D
STREET E
STREET E
STREET F
STREET F
ALLEY 2
ALLEY 1
ALLEY 3
ALLEY 4
ALLEY 8
ALLEY 8 ALLEY 8
ALLEY 5
ALLEY 6
ALLEY 7
ALLEY 9
ALLEY 9
ALLEY 9
ALLEY 12
ALLEY 10
ALLEY 10
ALLEY 11
ALLEY 13
STREET G
ALLEY 16
ALLEY 22
SUNIGA DRIVE
R1
R2
R3
R4-A
R4-B
R5
R6 R7
BIOSWALE R8
LID EXHIBIT
DRAINAGE REPORT
FORT COLLINS, CO
THRIVE
ENGINEER ING
N O R T H E RN
07.17.18
D:\PROJECTS\1496-001\DWG\EXHIBITS\1496-001_LID EXHIBIT.DWG
( IN FEET )
0
FORT COLLINS STORMWATER CRITERIA MANUAL Water Quality (Ch. 7)
5.0 Hydrologic Basis of the WQCV
5.0 Hydrologic Basis of the WQCV
Page 12
WQCV = a(0.91I3− 1.19I2+ 0.78𝐼𝐼) Equation 7-1
Where: WQCV = Water Quality Capture Volume, watershed inches
a = Coefficient corresponding to WQCV drain time (Table 5.4-1)
I = Imperviousness (%/100)
Table 5.4-1. Drain Time Coefficients for WQCV Calculations
Drain Time (hrs) Coefficient (a)
12 0.8
40 1.0
Reference: The UD-BMP excel-based spreadsheet, RG and EDB tabs may be used to aid in
calculating WQCV.
Figure 5.4-1 WQCV Based on BMP Drain Time
Once the WQCV in watershed inches is found from Figure 3.2-12 or using Equation 3.2-1, the
required BMP volume in acre-feet can be calculated as follows:
𝐕𝐕 = �
𝐖𝐖𝐖𝐖𝐖𝐖𝐕𝐕
𝟏𝟏𝟏𝟏
� 𝐀𝐀𝐀𝐀𝟏𝟏. 𝟏𝟏 Equation 7-2
Where: V = required volume, acre-ft
A = tributary catchment area upstream, acres
WQCV = Water Quality Capture Volume, watershed inches
1.2 = to account for the additional 20% of required storage for sedimentation accumulation
WATER QUALITY DESIGN CALCULATIONS
Rain Gardens R1 - R3
Rain Garden Water Quality Capture Volume (12-Hr. PLD)
Project: 1496-001
By: ATC
Date: 7/11/18
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 15.510 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 45.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.4500 <-- CALCULATED
WQCV (watershed inches) = 0.154 <-- CALCULATED from Figure 5.4-1, see following
Sediment Accumulation Factor = 1.20
WQCV (cu-ft) = 8691 <-- CALCULATED from Equation 7-2, see following
WATER QUALITY DESIGN CALCULATIONS
Rain Gardens R4a - R4b
Rain Garden Water Quality Capture Volume (12-Hr. PLD)
Project: 1496-001
By: ATC
Date: 7/11/18
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 10.680 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 45.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.4500 <-- CALCULATED
WQCV (watershed inches) = 0.154 <-- CALCULATED from Figure 5.4-1, see following
Sediment Accumulation Factor = 1.20
WQCV (cu-ft) = 5984 <-- CALCULATED from Equation 7-2, see following
WATER QUALITY DESIGN CALCULATIONS
Rain Gardens R5 - R7
Rain Garden Water Quality Capture Volume (12-Hr. PLD)
Project: 1496-001
By: ATC
Date: 7/11/18
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 18.450 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 45.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.4500 <-- CALCULATED
WQCV (watershed inches) = 0.154 <-- CALCULATED from Figure 5.4-1, see following
Sediment Accumulation Factor = 1.20
WQCV (cu-ft) = 10338 <-- CALCULATED from Equation 7-2, see following
WATER QUALITY DESIGN CALCULATIONS
Rain Garden R8
Rain Garden Water Quality Capture Volume (12-Hr. PLD)
Project: 1496-001
By: ATC
Date: 7/11/18
REQUIRED STORAGE & OUTLET WORKS:
TREATMENT AREA (ac) = 3.450 <-- INPUT from impervious calcs
PERCENT IMPERVIOUSNESS = 45.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.4500 <-- CALCULATED
WQCV (watershed inches) = 0.154 <-- CALCULATED from Figure 5.4-1, see following
Sediment Accumulation Factor = 1.20
WQCV (cu-ft) = 1933 <-- CALCULATED from Equation 7-2, see following
APPENDIX E
Erosion Control Report
Thrive
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.
MAP POCKET
Drainage Exhibit
UD
UD
UD
IRR
IRR IRR
IRR
IRR IRR IRR IRR
IRR IRR
UD
V.P.
V.P.
TEST
STA
V.P.
V.P.
TELE
TEST
STA
D
D
D
TELE
V.P.
V.P.
V.P.
S
H2O
S
GAS
TEST
STA
GAS
V.P.
TEST
STA
V.P.
WV
VAULT
ELEC
WV
V.P.
WV
WV
H2O
WV
V.WV P.
GAS T
SS
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
OHE OHE OHE OHE OHE
OHE OHE
OHE OHE
OHE OHE OHE
OHE OHE
OHE OHE OHE
OHE
OHE OHE
OHE
OHE OHE
OHE OHE
OHE OHE
OHE
OHE
OHE OHE OHE OHE OHE
W
TELE
GAS
D
TELE
R R
IRR IRR IRR IRR
IRR
IRR
IRR
IRR
IRR
H2O
GAS
GAS
H2O
IRR
D D
D
W
W W
UD
UD
UD
IRR
IRR IRR
IRR
IRR IRR IRR IRR
IRR IRR
UD
1
11.64
2
3.86
3
3.21
4
10.68
5
15.24
8
14.45
9
16.40
8 9
5
4
2
3
1
7
OS1
OS2
OS2
1.12
OS1
1.68
6
11.00
6
7
3.45
RAIN GARDEN 1
RAIN GARDEN 2 RAIN GARDEN 3
RAIN GARDEN 4-A
BIOSWALE
APPROXIMATE
EDGE OF WATER
RAIN GARDEN 5
RAIN GARDEN 6
RAIN GARDEN 7
STORM DRAIN
STORM DRAIN
STORM DRAIN
STORM DRAIN
STORM DRAIN
STORM DRAIN
STORM DRAIN
STORM DRAIN
STORM DRAIN
STORM DRAIN
RAIN GARDEN 4-B
APPROXIMATE EDGE
OF WETLANDS
SWALE
STORM DRAIN
STORM DRAIN
TIMBERLINE ROAD
MERGANSER
STREET A
STREET B
STREET B
STREET C STREET C
STREET C
STREET D
STREET D
STREET E
STREET E
STREET E
STREET F
STREET F
ALLEY 2
ALLEY 1
ALLEY 3
ALLEY 4
ALLEY 4
ALLEY 8
ALLEY 8 ALLEY 8
ALLEY 8
ALLEY 5
ALLEY 6
ALLEY 7
ALLEY 9
ALLEY 9
ALLEY 9
ALLEY 12
ALLEY 10
ALLEY 10
ALLEY 11
ALLEY 13
ALLEY 13
STREET G
STREET G
STREET H
STREET H
STREET H
ALLEY 15
ALLEY 15
ALLEY 16
ALLEY 16
ALLEY 16 ALLEY 16
ALLEY 17
ALLEY 18
ALLEY 19
ALLEY 20
ALLEY 21
ALLEY 16
ALLEY 22
ALLEY 23
ALLEY 24
ALLEY 25
SUNIGA DRIVE
OLD VINE DRIVE
ALLEY 14
RAIN GARDEN 8
C5.00
DRAINAGE EXHIBIT
A. CVAR
B. MATHISEN
1"=150'
NORTH
( IN FEET )
0
1 INCH = 150 FEET
150 300
19
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 UTILITY of Fort PLAN Collins, APPROVAL Colorado
Date
Date
Date
Date
Date
Date
APPROVED:
City Engineer
Traffic Engineer
Parks & Recreation
Stormwater Utility
Water & Wastewater Utility
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
Environmental Planner
No. Revisions:
By: Date:
REVIEWED BY:
C. SNOWDON
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
07/18/18
PROJECT:
1496-001
Sheet
THRIVE
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
07/18/18
E N G I N E E R I N G
N O R T H E RN
FORT COLLINS: 301 North Howes Street, Suite 100, 80521
GREELEY: 820 8th Street, 80631
970.221.4158
northernengineering.com
of 47
KEYMAP
R
R
SUNIGA DRIVE
N SUMMITVIEW DR
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
A
1 1
BASIN
DESIGNATION
BASIN
AREA (AC)
acres
RUNOFF
COEFFICIENTS
A
0.XX X.XXX
0.XX
LEGEND:
PROPERTY BOUNDARY
PROPOSED CURB AND GUTTER
PROPOSED SWALE
PROPOSED STORM INLET
PROPOSED STORM SEWER
EXISTING CONTOUR 5013
PROPOSED CONTOUR
DESIGN POINT
OVERLAND FLOW ARROW
DRAINAGE BASIN LABEL
DRAINAGE BASIN BOUNDARY
PROPOSED SWALE SECTION
C5.00
150 450
PROPOSED DIRECT FLOW
PROJECT BENCHMARKS:
Project Benchmarks:
92-1 - Located along East Vine Dr. at the Pleasant Valley and
Lake Canal, on a bridge on the top of the northwest headwall.
Elevation = 4946.31 (NAVD88)
2-07 - Located on Vine Drive, 0.1 mile West of Timberline Rd., 50ft
North of the entrance to Bull Run Townhomes on the Northwest
corner of the West catchbasin.
Elevation = 4959.98 (NAVD88)
Basis of Bearings
The Basis of Bearings is the South line of the Southwest Quarter of
Section 5 as bearing South 88°53'23" East (assumed bearing).
NOTES:
1. REFER TO THE "PRELIMNARY DRAINAGE REPORT FOR
THRIVE DATED JULY 18, 2018" BY NORTHERN ENGINEERING
FOR ADDITIONAL INFORMATION.
Pond ID Vol. (Ac-Ft)
100-Yr
WSEL (Ft)
WQ Capture
Vol. (Ac-Ft)
WQ WSEL
(Ft)
Total Req'd
Vol. (Ac-Ft)
100-Yr
Release (cfs)
Wetland 12.16 TBD 0.48 TBD 12.64 3.20
1 7.46 TBD 0.27 TBD 7.73 7.6
2 4.87 TBD N/A TBD 4.87 13.2
DRAINAGE SUMMARY TABLE
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
1 1 11.64 0.58 0.72 20.2 19.2 10.9 48.5
2 2 3.86 0.58 0.72 18.5 17.6 3.8 16.8
3 3 3.21 0.58 0.72 17.9 16.9 3.2 14.4
4 4 10.68 0.58 0.72 25.5 24.6 8.8 38.9
5 5 15.24 0.58 0.72 20.3 19.6 14.2 62.6
6 6 11.00 0.25 0.31 27.9 25.8 3.7 16.9
7 7 3.45 0.71 0.88 30.2 29.6 3.2 13.9
8 8 14.45 0.51 0.64 24.0 23.1 10.8 47.8
9 9 16.40 0.51 0.64 22.3 21.4 12.8 57.0
OS1 OS1 1.68 0.71 0.88 17.2 16.7 2.1 9.2
OS2 OS2 1.12 0.73 0.91 21.0 20.5 1.3 5.7
1 INCH = 100 FEET
150 150
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 12, Oct 10, 2017
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 20, 2015—Oct
15, 2016
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Custom Soil Resource Report
10
Tt
(min)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
1 1 No 0.25 0.25 0.31 105 2.00% 12.9 12.9 12.0 752 0.75% 1.73 7.2 0 0.00% N/A N/A 20 20 19
2 2 No 0.25 0.25 0.31 95 2.00% 12.3 12.3 11.4 640 0.75% 1.73 6.2 0 0.00% N/A N/A 18 18 18
3 3 No 0.25 0.25 0.31 120 2.00% 13.8 13.8 12.8 424 0.75% 1.73 4.1 0 0.00% N/A N/A 18 18 17
4 4 No 0.25 0.25 0.31 85 2.00% 11.6 11.6 10.8 1440 0.75% 1.73 13.9 0 0.00% N/A N/A 25 25 25
5 5 No 0.25 0.25 0.31 70 2.00% 10.6 10.6 9.8 1016 0.75% 1.73 9.8 0 0.00% N/A N/A 20 20 20
6 6 No 0.25 0.25 0.31 265 0.80% 27.9 27.9 25.8 0 0.75% N/A N/A 0 0.00% N/A N/A 28 28 26
7 7 No 0.25 0.25 0.31 35 2.00% 7.5 7.5 6.9 2360 0.75% 1.73 22.7 0 0.00% N/A N/A 30 30 30
8 8 No 0.25 0.25 0.31 95 2.00% 12.3 12.3 11.4 1216 0.75% 1.73 11.7 0 0.00% N/A N/A 24 24 23
9 9 No 0.25 0.25 0.31 80 2.00% 11.3 11.3 10.5 1142 0.75% 1.73 11.0 0 0.00% N/A N/A 22 22 21
OS1 OS1 No 0.25 0.25 0.31 30 2.00% 6.9 6.9 6.4 1073 0.75% 1.73 10.3 0 0.00% N/A N/A 17 17 17
OS2 OS2 No 0.25 0.25 0.31 32 2.00% 7.1 7.1 6.6 1441 0.75% 1.73 13.9 0 0.00% N/A N/A 21 21 20
Historic Site Historic Site No 0.25 0.25 0.31 230 0.90% 25.0 25.0 23.1 0 0.00% N/A N/A 1820 0.90% 1.42 21.3 46 46 44
TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point
Basin
Overland Flow
ATC
7/15/2018
Time of Concentration
(Equation RO-4)
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
OS1 73271 1.68 0.93 0.08 0.09 0.00 0.58 0.71 0.71 0.88 64%
OS2 48940 1.12 0.62 0.06 0.09 0.00 0.36 0.73 0.73 0.91 67%
Historic Site 4039779 92.74 0.00 0.02 0.18 0.00 92.54 0.25 0.25 0.31 0%
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. NOTE:
Impervious areas have been estimated for preliminary
design and planning purposes and are subject to change at Final Design.
10-year Cf = 1.00
7/15/2018