HomeMy WebLinkAboutNEC LAKE AND SHIELDS - PDP - PDP180012 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPRELIMINARY DRAINAGE REPORT
NEC LAKE AND SHIELDS
Fort Collins, Colorado
August 22, 2018
Prepared for:
CSURF
2537 Research Boulevard, Suite 200
Fort Collins, CO 80526
Prepared by:
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 232-047
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.
August 22, 2018
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage Report for
NEC Lake and Shields
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage Report for your review. This
report accompanies the Preliminary Development Review submittal for the proposed NEC Lake and
Shields.
This report has been prepared in accordance to the Fort Collins Stormwater Criteria Manual
(FCSCM), and serves to document the stormwater impacts associated with the proposed The NEC
Lake and Shields 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.
Cody Snowdon, PE Blaine Mathisen, EI
Project Manager Project Engineer
NEC Lake and Shields
Final Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 2
C. Floodplain.......................................................................................................................................... 3
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 5
A. Major Basin Description .................................................................................................................... 5
B. Sub-Basin Description ....................................................................................................................... 5
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 .............................................................................................................................. 7
F. Floodplain Regulations Compliance .................................................................................................. 7
G. Modifications of Criteria ................................................................................................................... 7
IV. DRAINAGE FACILITY DESIGN .................................................................................... 7
A. General Concept ............................................................................................................................... 7
B. Specific Details .................................................................................................................................. 8
V. CONCLUSIONS ...................................................................................................... 10
A. Compliance with Standards ............................................................................................................ 10
B. Drainage Concept ............................................................................................................................ 11
References ....................................................................................................................... 12
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations
B.1 – Storm Sewers (For Future Use)
B.2 – Inlets (For Future Use)
B.3 – Detention Facilities (For Future Use)
APPENDIX C – Water Quality Design Computations
APPENDIX D – Erosion Control Report
NEC Lake and Shields
Final Drainage Report
LIST OF TABLES AND FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2 – Proposed Site Plan ............................................................................................... 3
Figure 3 – Existing FEMA Floodplains .................................................................................... 4
Figure 4 – Existing City Floodplains ....................................................................................... 4
MAP POCKET:
Figure 1 - Existing Drainage Exhibit
C5.00 - Drainage Exhibit
NEC Lake and Shields
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. NEC Lake and Shields project is located in the southwest quarter of Section 14,
Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins,
County of Larimer, State of Colorado.
3. The project site is located at the northeast corner of Lake Street and Shields and
expands all the way to north to James Court. Prior to this project this land use to
encompass five residential homes with associated landscaping and hard surfaces.
These houses have already been removed. However, even though the houses have
already been removed they will be included in the rational calculations computation
for the existing basins. This will be discussed in greater detail in the following
sections.
4. Currently the existing lot does not have any stormwater or water quality facilities.
However, there is existing stormwater infrastructure to the east of the lot associated
with the Colorado State University Summit Hall Dorm parking lot. There are existing
detention ponds along the south and north side of that parking lot and a rain garden
along the north side of the parking lot as well. NEC Lake and Shields does not intend
to use any of CSU infrastructure for storage or water quality. However, NEC Lake and
Shields will be routing treated and detained flows through their systems in order for
the runoff to get into the public storm sewer maintained by the City because there is
NEC Lake and Shields
Preliminary Drainage Report 2
no storm infrastructure in either Lake Street or Shields Street. This will be discussed
in the following sections.
B. Description of Property
1. NEC Lake and Shields is approximately 2.17 net acres.
Figure 1 – Aerial Photograph
2. NEC Lake and Shields use to have residential homes with associated driveways and
landscaping but since the purchase of the land by CSURF these structures have since
been removed. These houses and associated driveways were taken into consideration
when determining the existing impervious area.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey, 100 percent of the site consists of Altvan-
Satanta loam, which falls into Hydrologic Soil Groups B.
4. The proposed development will include the demolition of the existing drive aisle off of
Lake Street, the abandonment of all water and sanitary services currently feeding into
the site as well as some tree removals. The proposed project will include a single story
commercial building for daycare use. There will be associated play places, sidewalks,
and parking associated with this development. The current drive aisle off of Lake
Street will be removed and replaced with a new drive entrance just east of where it
currently is at. NEC Lake and Shields will be providing water quality in both LID and
traditional methods. NEC Lake and Shields will also have two separate detention
ponds that will release at reduced allowable rates. More details and discussion with
regards to water quality and storage amenities can be found in the proceeding
sections.
NEC Lake and Shields
Preliminary Drainage Report 3
Figure 2– Proposed Site Plan
5. No irrigation facilities or major drainageways are within the property limits.
6. The project site is within the High Density Mixed-Use Neighborhood District (H-M-N)
Zoning District. The proposed use is permitted within the zone district.
C. Floodplain
1. The subject property is not located in a FEMA or City regulatory floodplain.
2. The FEMA Panel 08069C0978G illustrates the proximity of the project site to the
nearest FEMA delineated regulatory floodplain.
NEC Lake and Shields
Preliminary Drainage Report 4
Figure 3 – Existing FEMA Floodplains
Figure 4 – Existing City Floodplains
NEC Lake and Shields
Preliminary Drainage Report 5
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. NEC Lake and Shields is located within the Old Town Basin, which is located
primarily in Old Town Fort Collins.
B. Sub-Basin Description
1. The property historically generally drains west to east via overland flow except for the
northwest corner of the site which sheet flows north off the site into James Court. All
flows generated and routed to James Court are conveyed east towards a concrete pan
and curb chase at the end of the street which directs flow into the existing detention
pond at the northeast corner of the existing parking lot. The project was broken down
into seven separate basins. However, all the flows generated on the existing site all
eventually make their way into the northeast detention pond associated with the CSU
Summit Hall Dorm parking lot. The southern portion of the site is currently being
conveyed into the southern detention pond. The southern detention pond then
conveys flows north towards the northern pond. Therefore, all the flows are eventually
routed to that northern detention pond. The proposed project will maintain these
same existing flows/ See Section IV.A.4. below, for a more detailed description of the
projects proposed drainage patterns.
2. No drainage is routed onto the property from the surrounding properties.
A full-size copy of the Proposed Drainage Exhibit can be found in the Map Pocket at
the end of this report.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with NEC Lake and
Shields project.
B. Four Step Process
The overall stormwater management strategy employed with NEC Lake and Shields 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:
Selecting a site that has been previously developed and that use consist of five single
family residences with associated hardscapes and landscaping.
Providing vegetated open areas along the south, north, and east portion of the site to
reduce the overall impervious area and to minimize directly connected impervious
areas (MDCIA).
Routing flows, to the extent feasible, through rain gardens and to increase time of
concentration, promote infiltration and provide initial water quality.
NEC Lake and Shields
Preliminary Drainage Report 6
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, this
development will still generate stormwater runoff that will require additional BMPs and
water quality. The stormwater generated from the building will be split and more than half
of it will go towards the rain gardens. The runoff from the proposed parking lot and the
new drive aisle off of Lake Street will be routed towards rain gardens. The water quality
event will be filtered through the sand layers and discharge into the South Pond where the
flows will then leave the site at a reduced existing rate. The runoff that is generated by the
sidewalk along James Court and the northern half of the building will receive traditional
water quality in the North Pond. However, 75% the impervious area is being treated by
rain gardens.
Step 3 – Stabilize Drainageways
As stated in Section I.B.5, above, there are no major drainageways in or near the subject
site. While this step may not seem applicable to NEC Lake and Shields, the proposed
project indirectly helps achieve stabilized drainageways nonetheless. Once again, site
selection has a positive effect on stream stabilization. By repurposing an already
developed, under-utilized site with no existing stormwater infrastructure, combined with
LID, the likelihood of bed and bank erosion is greatly reduced. Furthermore, this project
will pay one-time stormwater development fees, as well as ongoing monthly stormwater
utility fees, both of which help achieve Citywide drainageway stability.
Step 4 – Implement Site Specific and Other Source Control BMPs.
This step typically applies to industrial and commercial developments and is not
applicable for this project.
C. Development Criteria Reference and Constraints
1. There are no known drainage studies for the existing properties.
2. The subject property is essentially an "in-fill" development project as the property is
surrounded by currently developed properties. As such, several constraints have been
identified during the course of this analysis that will impact the proposed drainage
system including:
Existing elevations all along the property line need to be maintained in order to tie
into existing infrastructure.
As previously mentioned, overall drainage patterns within the Master Drainage
Basin will be maintained. To alleviate the current drainage problem within West
Lake Street, all of the drainage will be routed north towards James Court and into
the existing drainage pond at the northeast corner of the existing parking lot via
storm pipes.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
associated with this development. Tabulated data contained in Table RA-7 has been
utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
NEC Lake and Shields
Preliminary Drainage Report 7
3. The Rational Formula-based Modified Federal Aviation Administration (FAA)
procedure has been utilized for detention storage calculations.
4. 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.
5. No other assumptions or calculation methods have been used with this development
that are not referenced by current City of Fort Collins criteria.
E. Hydraulic Criteria
1. As previously noted, the subject property historically drains towards the existing
detention ponds that are along both north and south edges of the existing dorm
parking lot. The majority of the site drains stormwater via overland flow.
2. All drainage facilities proposed with NEC Lake and Shields project are designed in
accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood
Control District’s (UDFCD) Urban Storm Drainage Criteria Manual.
3. As stated in Section I.C.1, above, the subject property is not located within any
regulatory floodplain.
4. NEC Lake and Shields project does not propose to modify any natural drainageways.
F. Floodplain Regulations Compliance
1. As previously mentioned, all structures are located outside of any FEMA 100-year or
City floodplain, and thus are not subject to any floodplain regulations.
G. Modifications of Criteria
1. The proposed NEC Lake and Shields development is not requesting any modification
at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of NEC Lake and Shields drainage design is to maintain existing
drainage patterns, minimize the amount of drainage routed to West Lake Street and
ensure no adverse impacts to any adjacent properties.
2. As previously mentioned, there are no off-site flows draining onto the existing
property.
3. A list of tables and figures used within this report can be found in the Table of
Contents at the front of the document. The tables and figures are located within the
sections to which the content best applies.
4. NEC Lake and Shields project is composed of four major drainage basins, designated
as Basins N1, S1, S2, and OS1. The drainage patterns for each major basin are
further described below.
NEC Lake and Shields
Preliminary Drainage Report 8
Basin N
Basin N is associated with a portion of the building, sidewalks adjacent to James
Court and Shields Street, as well as the landscaping and play ground areas to the
north and west of the building. Runoff generated in Basin N will receive standard
water quality and will be released at a portion of the allowable release rate out of the
North Pond.
Basin S1
Basin S1 is associated with the remaining portion of the building, the entire proposed
parking lot, and all the landscaping to the south of the building. Runoff generated in
this basin will sheet flow towards a curb and sidewalk chase which will then convey
the runoff into Rain Garden 1. Rain Garden 1 was sized to adequately treat the water
quality event for this basin. Once the water quality event volume is achieved the runoff
will then be routed via an overflow outfall basin within Rain Garden 1 which will then
convey everything above the water quality event into the South Pond. The South Pond
will be releasing at a portion of the allowable release rate
Basin S2
Basin S2 is exclusively associated with the new drive aisle off Lake Street. All the
runoff generated in this drive aisle will be conveyed via curb and gutter into a sidewalk
chase which will then convey the runoff into Rain Garden 2. Rain Garden 2 was sized
to adequately treat the water quality event associated with Basin S2. Just like Basin
S1, once the water quality event has been met there will be an overflow basin that will
convey anything above the water quality event into the South Pond. The South Pond
will be releasing at a portion of the allowable release rate.
Basin OS1
Basin OS1 is associated with the area along Shields Street and James Court that was
not capturable. Runoff generated in this basin will flow north along Shields Street
where it will then turn the corner at James Court and flow east where it will eventually
enter the site at an existing 2’ concrete pan that leads into the existing detention pond
at the northeast corner of the dorm parking lot. Since Basin OS1 is leaving the site
undetained the 100-year flow rate generated by this basin will be subtracted from the
existing allowable release rate. Additional clarification on this reduction in allowable
release rate is in the proceeding sections.
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. The main drainage problem associated with this project site is the deficiency of
water quality present within the existing site as well as grading constraints. The
northern portion of the site drains overland and is captured in the North Pond. The
North Pond will be releasing at a portion of the allowable release rate into the
existing rain garden and detention pond adjacent to the north side of the existing
NEC Lake and Shields
Preliminary Drainage Report 9
parking lot. This is the historic pattern of this basin, so no adverse impacts should
occur within the existing drainage ponds. The southern portion of the site drains
via overland and concentrated flows and discharges directly into one of the two
rain gardens. Once the rain gardens are full all excess runoff is routed towards the
South Pond. The South Pond will be discharging at a portion of the allowable
release rate into the existing detention pond along the southern side of the existing
parking lot. Because the South Pond is releasing at a portion of the allowable
release rate no adverse impacts on the existing detention pond are expected.
All of the runoff generated in Basins S1 and S2 will be routed towards a rain
garden for initial water quality that will promote infiltration.
All of the runoff generated in Basin N1 will be routed towards the North Pond
where it will receive traditional water quality.
The landscape areas surrounding the project (Basin OS1) will be treated by use of
a grass buffer.
2. The release rate for the undeveloped land (pre-development) was established by
calculating the 2-year peak runoff rate of the existing pervious area and the 100-year
peak runoff rate of the existing impervious area located within the project area,
resulting in an overall release of 5.16 cfs. In excluding all portions of the proposed
project that releases undetained (Basin OS1), the overall allowable peak runoff rate
for the remaining site was calculated at 4.78 cfs. This remaining release rate was
divided among the North Pond and South Pond associated with detention for Basins
N1, S1, and S2. These release rates were utilized in the FAA method for design of
the North and South ponds. (Refer to Appendix B for these calculations).
3. Detention Pond Calculations
North Pond
Calculations for North Pond, based on the characteristics of Basin N1, and an
adjusted release rate of 1.25 cfs, indicate a detention volume of 1250 cu. ft. This
volume does not include the 12-hour release WQCV calculated for this basin (270
cu. ft.), therefore the overall volume is 1533 cu. ft. The North Pond does not have
any LID component therefore this is just standard water quality. The North Pond has
a spill elevation of 5029.00 which is well below the building finish floor elevation
(FFE) of 5032.77. The North Pond will discharge west via a storm pipe into the
existing detention pond along the north side of the existing parking lot. In the case
that the outfall structure gets clogged or an event greater than the 100-year event
comes along the overflow path will convey the runoff northeast out of the site into
James Court, where it historically has gone.
South Pond
Calculations for Pond N3, based on the characteristics of Basins S1 and S1 and an
adjusted release rate of 3.53 cfs, indicate a detention volume of 6118 cu. ft. This
does not include the water quality capture volume (WQCV) associated with Basins S1
and S2. As previously mentioned Basins S1 and S2 are receiving water quality within
the rain gardens. The overflow elevation of South Pond is 5028.04, therefore there is
adequate difference between the FFE (5032.77) and the top water surface elevation.
The South Pond will discharge west via a storm pipe into the existing detention pond
along the south side of the existing parking lot. In the case that the outlet structure is
clogged or excess runoff above the 100-year event is inundating the pond the excess
flows will overflow at the northeast corner of the pond and follow the existing
NEC Lake and Shields
Preliminary Drainage Report 10
drainage pattern.
4. Water Quality Results
North Pond
As previously mentioned Basin N1 is going to be treated via traditional extended
detention water quality. Based on characteristics of Basin N1 the required water
quality capture volume (WQCV) is 270 cu. ft. This required storage was added onto
the required detention volume as mentioned previously. A water quality plate on the
outlet structure will insure that the WQCV is adequately met.
Rain Garden 1
Rain Garden 1 was sized based on the characteristics of Basin S1. Following Urban
Drainage requirements, the required WQVC is 901.7 cu. ft. However, there was
additional room to slightly increase the size of Rain Garden 1 to treat a WQCV of 915
cu. ft. Rain Garden 1 has a ponding depth of 1’ until runoff starts to enter the
overflow basin. All treated runoff and excess runoff will be conveyed to the South
Pond via underdrains and storm pipe where it will be detained.
Rain Garden 2
Rain Garden 2 was sized based on the characteristics of Basin S2. Following Urban
Drainage requirements, the required WQVC is 96.9 cu. ft. However, there was
additional room to increase the size of Rain Garden 2 to treat a WQCV of 431 cu. ft.
Rain Garden 2 has a ponding depth of 1’ until runoff starts to enter the overflow
basin. All treated runoff and excess runoff will be conveyed to the South Pond via
underdrains and storm pipe where it will be detained.
Between the traditional water quality associated with the North Pond and Rain
Gardens 1 and 2, NEC Lake and Shields will be treating a total of 1616 cu. ft. of
runoff. This results in 347 cu. ft. of extra water quality that is not required of NEC
Lake and Shields.
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with NEC Lake and Shields project complies with the
City of Fort Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with NEC Lake and Shields project complies with the
City of Fort Collins’ Master Drainage Plan for the Old Town Basin.
3. There are no regulatory floodplains associated with NEC Lake and Shields
development.
4. The drainage plan and stormwater management measures proposed with NEC Lake
and Shields development are compliant with all applicable State and Federal
regulations governing stormwater discharge.
NEC Lake and Shields
Preliminary Drainage Report 11
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit potential damage
associated with its stormwater runoff. NEC Lake and Shields will detain for the
pervious area converted to impervious areas by releasing at the 2-year existing rate
during the developed100-year storm.
2. The proposed NEC Lake and Shields development will not impact the Master Drainage
Plan recommendations for the Old Town major drainage basin.
NEC Lake and Shields
Preliminary Drainage Report 12
References
1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities,
November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services.
2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No.
174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code.
3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
APPENDIX A
HYDROLOGIC COMPUTATIONS
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: NEC Lake and Shields
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen
Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….. 0.50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year C
f = 1.00 100-year C
f = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
EX-1 23625 0.54 0.00 0.01 0.00 0.00 0.53 0.17 0.17 0.21 2%
EX-2 4543 0.10 0.00 0.00 0.02 0.03 0.06 0.39 0.39 0.48 27%
EX-3 21995 0.50 0.00 0.00 0.10 0.09 0.31 0.38 0.38 0.47 26%
EX-4 13743 0.32 0.00 0.00 0.05 0.01 0.26 0.29 0.29 0.36 16%
EX-5 1822 0.04 0.00 0.00 0.01 0.00 0.02 0.48 0.48 0.60 37%
EX-6 16073 0.37 0.02 0.00 0.00 0.00 0.35 0.20 0.20 0.25 6%
EX-7 12649 0.29 0.05 0.00 0.06 0.00 0.19 0.43 0.43 0.54 33%
Total 94450 2.17 0.07 0.02 0.24 0.13 1.71 0.29 0.29 0.36 16%
Existing Impervious
Overland Flow, Time of Concentration:
Project: NEC Lake and Shields
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: NEC Lake and Shields
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
ex-1 EX-1 0.54 16 16 15 0.17 0.17 0.21 1.84 3.14 6.52 0.17 0.28 0.74
ex-2 EX-2 0.10 8 8 7 0.39 0.39 0.48 2.46 4.21 9.06 0.10 0.17 0.46
ex-3 EX-3 0.50 15 15 13 0.38 0.38 0.47 1.90 3.24 7.04 0.36 0.62 1.68
ex-4 EX-4 0.32 18 18 16 0.29 0.29 0.36 1.73 2.95 6.41 0.16 0.27 0.73
ex-5 EX-5 0.04 6 6 5 0.48 0.48 0.60 2.67 4.56 9.95 0.05 0.09 0.25
ex-6 EX-6 0.37 18 18 17 0.20 0.20 0.25 1.70 2.90 6.10 0.12 0.21 0.56
ex-7 EX-7 0.29 7 7 6 0.43 0.43 0.54 2.60 4.44 9.63 0.33 0.56 1.51
N/A
Existing Impervious
Area Breakdown 0.46
8 8 5 0.82 0.82 1.00 2.40 4.10 9.95 0.90 1.54 4.54
N/A
Existing Pervious
Area Breakdown 1.71
8 8 5 0.15 0.15 0.19 2.40 4.10 9.95 0.62 1.05 3.19
HISTORIC RUNOFF COMPUTATIONS
Intensity,
i2
(in/hr)
Intensity,
i10
(in/hr)
Intensity,
i100
(in/hr)
Notes
B. Mathisen
August 21, 2018
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
Design
Point
Basin(s)
Area, A
(acres)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
Flow,
Q2
(cfs)
C2
Total allowable release = 5.16
Flow,
Q10
(cfs)
Flow,
Q100
(cfs)
C10
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: NEC Lake and Shields
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen
Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 90%
Gravel ……….…………………….….…………………………..……………………………….. 0.50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year C
f = 1.00 100-year C
f = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
N1 18506 0.42 0.00 0.16 0.08 0.00 0.19 0.60 0.60 0.75 50%
S1 67339 1.55 0.40 0.21 0.17 0.00 0.76 0.56 0.56 0.70 48%
S2 2906 0.07 0.07 0.00 0.00 0.00 0.00 0.95 0.95 1.00 100%
OS1 5699 0.13 0.00 0.01 0.00 0.00 0.12 0.23 0.23 0.29 9%
Total 94450 2.17 0.47 0.38 0.25 0.00 1.07 0.56 0.56 0.70 48%
PROPOSED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Notes
August 21, 2018
10-year Cf
Overland Flow, Time of Concentration:
Project: NEC Lake and Shields
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: NEC Lake and Shields
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
n1 N1 0.42 6 6 5 0.60 0.60 0.75 2.76 4.72 9.95 0.70 1.19 3.15
s1 S1 1.55 10 10 7 0.56 0.56 0.70 2.26 3.86 8.80 1.94 3.32 9.46
s2 S2 0.07 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.18 0.31 0.66
os1 OS1 0.13 5 5 5 0.23 0.23 0.29 2.85 4.87 9.95 0.09 0.15 0.38
C2
Flow,
Q10
(cfs)
Flow,
Q100
(cfs)
C10
C100
PROPOSED RUNOFF COMPUTATIONS
Intensity,
i2
(in/hr)
Intensity,
i10
(in/hr)
Intensity,
i100
(in/hr)
Notes
B. Mathisen
August 21, 2018
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
Design
Point
Basin(s)
Area, A
(acres)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
Flow,
Q2
(cfs)
Q = C f ( C )( i )( A )
Page 3 of 21 D:\Projects\232-047\Drainage\Hydrology\232-047_Proposed Rational-Calcs.xlsx\DirectRunoff
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 – Storm Sewers (Future Use)
B.2 – Inlets (Future Use)
B.3 – Detention Facilities
APPENDIX B.1
STORM SEWERS (FOR FUTURE USE)
APPENDIX B.2
INLETS (FOR FUTURE USE)
APPENDIX B.3
DETENTION FACILITIES
Pond No :
n1
100-yr
0.75
5.00 min 1250 ft3
0.42 acres 0.029 ac-ft
Max Release Rate = 1.25 cfs
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 940 1.00 1.25 375 565
10 7.720 1459 0.75 0.94 563 897
15 6.520 1848 0.67 0.83 750 1098
20 5.600 2117 0.63 0.78 938 1179
25 4.980 2353 0.60 0.75 1125 1228
30 4.520 2563 0.58 0.73 1313 1250
35 4.080 2699 0.57 0.71 1500 1199
40 3.740 2827 0.56 0.70 1688 1140
45 3.460 2943 0.56 0.69 1875 1068
50 3.230 3052 0.55 0.69 2063 990
55 3.030 3150 0.55 0.68 2250 900
60 2.860 3243 0.54 0.68 2438 806
65 2.720 3342 0.54 0.67 2625 717
70 2.590 3427 0.54 0.67 2813 614
75 2.480 3515 0.53 0.67 3000 515
80 2.380 3599 0.53 0.66 3188 411
85 2.290 3679 0.53 0.66 3375 304
90 2.210 3759 0.53 0.66 3563 197
95 2.130 3824 0.53 0.66 3750 74
100 2.060 3893 0.53 0.66 3938 -44
105 2.000 3969 0.52 0.65 4125 -156
110 1.940 4033 0.52 0.65 4313 -279
115 1.890 4108 0.52 0.65 4500 -392
120 1.840 4173 0.52 0.65 4688 -514
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
A =
Tc =
Project Location :
Design Point
C =
Design Storm
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
Invert Elevation
Water Quality Volume
100-yr Detention Volume
Total Pond Volume
Min Sc
D = Depth between contours (ft.)
A1
= Surface Area lower contour (ft
2
) t
A2
= Surface Area upper contour (ft
2
) Area/Row
No. of Rows
5026.80 1.75 0.05 0.03 0.03 0.0000
5027.00 41.33 0.20 3.44 3.47 0.0001
5027.20 109.83 0.20 14.57 18.04 0.0004
5027.40 200.71 0.20 30.60 48.64 0.0011
5027.60 313.97 0.20 51.05 99.69 0.0023
5027.80 449.62 0.20 75.95 175.64 0.0040
5028.00 637.56 0.20 108.17 283.81 0.0065 WQCV
5028.20 798.05 0.20 143.26 427.07 0.0098
5028.40 991.24 0.20 178.58 605.65 0.0139
5028.60 1238.04 0.20 222.47 828.12 0.0190
5028.80 1418.79 0.20 265.48 1093.60 0.0251
5029.00 4603.50 0.20 571.86 1665.47 0.0382 Total Vol
5029.20 1792.17 0.20 617.87 2283.33 0.0524
Elevation Depth Volume
WQCV 5027.97 1.22 0.0062
100-yr Detention 5028.86 2.11 0.0290
Overall Detention 5028.95 2.20 0.0352
Circular Perforation Sizing
Dia (in.)
1
North Pond
0.05
6
0.0062 ac-ft
5026.75 ft
North Pond Volume
Elevation
(ft)
n
1/4
0.015 sq-in
Surface
Area (ft2) Total Outlet
Area
0.30 sq. in.
Sunshine House 8/21/2018
232-047 B. Mathisen
CSURF
0.0352 ac-ft
0.0290 ac-ft
Required Area
Pond No :
s1
100-yr
0.75
5.00 min 6118 ft3
1.61 acres 0.140 ac-ft
Max Release Rate = 3.53 cfs
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 3604 1.00 3.53 1059 2545
10 7.720 5593 0.75 2.65 1589 4005
15 6.520 7086 0.67 2.35 2118 4968
20 5.600 8114 0.63 2.21 2648 5467
25 4.980 9020 0.60 2.12 3177 5843
30 4.520 9824 0.58 2.06 3707 6118
35 4.080 10346 0.57 2.02 4236 6110
40 3.740 10839 0.56 1.99 4766 6073
45 3.460 11280 0.56 1.96 5295 5985
50 3.230 11701 0.55 1.94 5825 5876
55 3.030 12074 0.55 1.93 6354 5720
60 2.860 12432 0.54 1.91 6884 5549
65 2.720 12809 0.54 1.90 7413 5396
70 2.590 13135 0.54 1.89 7943 5193
75 2.480 13476 0.53 1.88 8472 5004
80 2.380 13794 0.53 1.88 9002 4793
85 2.290 14102 0.53 1.87 9531 4571
90 2.210 14410 0.53 1.86 10061 4350
95 2.130 14660 0.53 1.86 10590 4070
100 2.060 14925 0.53 1.85 11120 3805
105 2.000 15215 0.52 1.85 11649 3566
110 1.940 15461 0.52 1.85 12179 3282
115 1.890 15747 0.52 1.84 12708 3039
120 1.840 15997 0.52 1.84 13238 2759
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
A =
Tc =
Project Location :
Design Point
C =
Design Storm
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, Colorado
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
Invert Elevation
Water Quality Volume
100-yr Detention Volume
Total Pond Volume
Min Sc
D = Depth between contours (ft.)
A1
= Surface Area lower contour (ft
2
) t
A2
= Surface Area upper contour (ft
2
) Area/Row
No. of Rows
5024.20 5.18 0.02 0.04 0.04 0.0000 WQCV
5024.40 516.70 0.20 38.24 38.28 0.0009
5024.60 715.86 0.20 122.72 161.00 0.0037
5024.80 810.66 0.20 152.55 313.55 0.0072
5025.00 909.62 0.20 171.93 485.48 0.0111
5025.20 1012.72 0.20 192.14 677.63 0.0156
5025.40 1119.97 0.20 213.18 890.80 0.0205
5025.60 1231.37 0.20 235.05 1125.85 0.0258
5025.80 1346.92 0.20 257.74 1383.59 0.0318
5026.00 1466.61 0.20 281.27 1664.86 0.0382
5026.20 1590.46 0.20 305.62 1970.48 0.0452
5026.40 1718.45 0.20 330.81 2301.29 0.0528
5026.60 1850.59 0.20 356.82 2658.12 0.0610
5026.80 1986.88 0.20 383.67 3041.78 0.0698
5027.00 2127.31 0.20 411.34 3453.12 0.0793
5027.20 2271.90 0.20 439.84 3892.96 0.0894
5027.40 2420.69 0.20 469.18 4362.14 0.1001
5027.60 2573.51 0.20 499.34 4861.48 0.1116
5027.80 2742.73 0.20 531.53 5393.02 0.1238
5028.00 3109.58 0.20 584.85 5977.87 0.1372
5028.20 3703.06 0.20 680.40 6658.27 0.1529 Total Vol
5028.40 4275.00 0.20 797.12 7455.39 0.1712
Elevation Depth Volume
WQCV 0.00 0.00 0.0000
100-yr Detention 5028.04 3.86 0.1400
Overall Detention 5028.04 3.86 0.1400
Required Area
Per Row
Total Vol.
(ac-ft)
Total Vol.
(ft3)
Incremental
Vol. (ft3)
Incremental
Depth (ft)
Surface
Area (ft2) Total Outlet
Area
0.55 sq. in.
NEC Lake and Shields 8/21/2018
APPENDIX C
WATER QUALITY DESIGN COMPUTATIONS
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
0.8
WQCV = Watershed inches of Runoff (inches) 50.00%
a = Runoff Volume Reduction (constant)
i = Total imperviousness Ratio (i = Iwq/100) 0.165 in
A = 0.45 ac
V = 0.0062 ac-ft 269.53 cu. ft.
V = Water Quality Design Volume (ac-ft)
WQCV = Water Quality Capture Volume (inches)
A = Watershed Area (acres)
Sunshine House August 21, 2018
232-047 B. Mathisen
CSURF
NEC Lake and Shields
Drain Time
a =
i =
WQCV =
Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event
0.165
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
WQCV (watershed inches)
Total Imperviousness Ratio (i = Iwq
/100)
Water Quality Capture Volume
6 hr
12 hr
24 hr
40 hr
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i )
V * A
12
WQCV
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 48.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.480
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.16 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 67,339 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.43 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 901.7 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 646 sq ft
D) Actual Flat Surface Area AActual = 657 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 1173 sq ft
F) Rain Garden Total Volume VT= 915 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = 1.5 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 902 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 3/4 in
Design Procedure Form: Rain Garden (RG)
Blaine Mathisen
Northern Engineering
August 21, 2018
Sunshine House
Rain Garden 1
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.06-SouthRG1.xlsm, RG 8/21/2018, 9:00 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Blaine Mathisen
Northern Engineering
August 21, 2018
Sunshine House
Rain Garden 1
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.06-SouthRG1.xlsm, RG 8/21/2018, 9:00 AM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 100.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 1.000
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.40 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 2,906 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.43 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 96.9 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 58 sq ft
D) Actual Flat Surface Area AActual = 232 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 630 sq ft
F) Rain Garden Total Volume VT= 431 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = 1.5 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 97 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 1/4 in LESS THAN MINIMUM. USE DIAMETER OF 3/8"
Design Procedure Form: Rain Garden (RG)
Blaine Mathisen
Northern Engineering
August 21, 2018
Sunshine House
Rain Garden 2
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.06-SouthRG2.xlsm, RG 8/21/2018, 8:51 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Blaine Mathisen
Northern Engineering
August 21, 2018
Sunshine House
Rain Garden 2
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.06-SouthRG2.xlsm, RG 8/21/2018, 8:51 AM
Design
Point
Basin ID
Basin Impervious
Area (sq. ft.)
Treatment
Type
LID System
Area Treated by
LID System (sq. ft.)
Percent of
Site
n1 N1 10321
Standard
WQ
No N/A 0%
s1 S1 34208 Rain Garden Yes 34208 71%
s2 S2 2906 Rain Garden Yes 2906 6%
OS1 600 Grass Buffer No N/A 0%
Total 48035 37114 77%
LID SUMMARY TABLE
APPENDIX D
EROSION CONTROL REPORT
NEC Lake and Shields
Final Erosion Control Report
A comprehensive Erosion and Sediment Control Plan (along with associated details) will be included
with the final construction drawings. It should be noted, however, that any such Erosion and
Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of
the BMPs depicted, and additional or different BMPs from those included may be necessary during
construction, or as required by the authorities having jurisdiction.
It shall be the responsibility of the Contractor to ensure erosion control measures are properly
maintained and followed. The Erosion and Sediment Control Plan is intended to be a living
document, constantly adapting to site conditions and needs. The Contractor shall update the
location of BMPs as they are installed, removed or modified in conjunction with construction
activities. It is imperative to appropriately reflect the current site conditions at all times.
The Erosion and Sediment Control Plan shall address both temporary measures to be implemented
during construction, as well as permanent erosion control protection. Best Management Practices
from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are
not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways
and inlet protection at proposed storm inlets. Vehicle tracking control pads, spill containment and
clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall
also be provided by the Contractor.
Grading and Erosion Control Notes can be found on Sheet C0.01 of the Utility Plans. The Utility
Plans at final design will also contain a full-size Erosion Control Plan as well as a separate sheet
dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the
Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing
Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior
to issuance of the Development Construction Permit. Also, the Site Contractor for this project will
be required to secure a Stormwater Construction General Permit from the Colorado Department of
Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program,
before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor
shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE
requirements and guidelines. The SWMP will further describe and document the ongoing activities,
inspections, and maintenance of construction BMPs.
APPENDIX E
Soils Resource Report
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
August 20, 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
3—Altvan-Satanta loams, 0 to 3 percent slopes......................................... 13
References............................................................................................................16
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
4490900 4490920 4490940 4490960 4490980 4491000 4491020 4491040
4490900 4490920 4490940 4490960 4490980 4491000 4491020 4491040
491880 491900 491920 491940 491960 491980 492000
491880 491900 491920 491940 491960 491980 492000
40° 34' 12'' N
105° 5' 45'' W
40° 34' 12'' N
105° 5' 40'' W
40° 34' 7'' N
105° 5' 45'' W
40° 34' 7'' N
105° 5' 40'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 35 70 140 210
Feet
0 10 20 40 60
Meters
Map Scale: 1:819 if printed on A portrait (8.5" x 11") 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
3 Altvan-Satanta loams, 0 to 3
percent slopes
2.1 100.0%
Totals for Area of Interest 2.1 100.0%
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
3—Altvan-Satanta loams, 0 to 3 percent slopes
Map Unit Setting
National map unit symbol: jpw2
Elevation: 5,200 to 6,200 feet
Mean annual precipitation: 13 to 15 inches
Mean annual air temperature: 48 to 50 degrees F
Frost-free period: 135 to 150 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Altvan and similar soils: 45 percent
Satanta and similar soils: 30 percent
Minor components: 25 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Altvan
Setting
Landform: Benches, terraces
Landform position (three-dimensional): Side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 18 inches: clay loam, loam, sandy clay loam
H2 - 10 to 18 inches: loam, fine sandy loam, silt loam
H2 - 10 to 18 inches: gravelly sand, gravelly coarse sand, coarse sand
H3 - 18 to 30 inches:
H3 - 18 to 30 inches:
H3 - 18 to 30 inches:
H4 - 30 to 60 inches:
H4 - 30 to 60 inches:
H4 - 30 to 60 inches:
Properties and qualities
Slope: 0 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Available water storage in profile: Very high (about 13.2 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 3e
Custom Soil Resource Report
13
Hydrologic Soil Group: B
Hydric soil rating: No
Description of Satanta
Setting
Landform: Structural benches, terraces
Landform position (three-dimensional): Side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium and/or eolian deposits
Typical profile
H1 - 0 to 9 inches: loam
H2 - 9 to 18 inches: loam, clay loam, sandy clay loam
H2 - 9 to 18 inches: loam, clay loam, fine sandy loam
H2 - 9 to 18 inches:
H3 - 18 to 60 inches:
H3 - 18 to 60 inches:
H3 - 18 to 60 inches:
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Available water storage in profile: Very high (about 27.4 inches)
Interpretive groups
Land capability classification (irrigated): 1
Land capability classification (nonirrigated): 3c
Hydrologic Soil Group: B
Hydric soil rating: No
Minor Components
Nunn
Percent of map unit: 10 percent
Hydric soil rating: No
Larim
Percent of map unit: 10 percent
Hydric soil rating: No
Stoneham
Percent of map unit: 5 percent
Hydric soil rating: No
Custom Soil Resource Report
14
Custom Soil Resource Report
15
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
16
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
17
MAP POCKET
HISTORIC DRAINAGE EXHIBIT
PROPOSED DRAINAGE EXHIBIT
EX-1
EX-3
EX-2
EX-4
EX-5
0.54 ACRES
23624.61 SQFT
0.50 ACRES
21994.80 SQFT
0.32 ACRES
13743.42 SQFT
EX-6
0.37 ACRES EX-7
16073.14 SQFT
0.29 ACRES
0.04 ACRES 12649.28 SQFT
1822.38 SQFT
0.10 ACRES
4543.19 SQFT
ex-1
ex-2
ex-3
ex-4
ex-5
ex-6 ex-7
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
ST
X
X
X
X X X X X X X
F
E
S
F
E
S
F
E
S
D
X
X
X
X X
X
X X
X
X
X X
X
X
X X X X X X X
T
CABLE
D
C
C
X X X X
T C
S1
S2
N1
OS1
os1
n1
s1
s2
RAIN
GARDEN 1
SOUTH
POND
NORTH
POND
2' CONCRETE PAN
OUTFALL
RAIN GARDEN 1
OVERFLOW OUTFALL
CURB AND
SIDEWALK
CHASE
OUTFALL
ROOF LEADER
CONNECTIONS (3)
SHIELDS ST.
LAKE ST.
JAMES CT.
RAIN
GARDEN 2
RAIN GARDEN 2
OVERFLOW OUTFALL
SIDEWALK CHASE
EXISTING 2' PAN
EXISTING CURB
CHASE
EXISTING OUTLET STRUCTURE
FLOWLINE ELEV. = 5019.95
EXISTING FES
FLOWLINE ELEV. = 5020.59
EXISTING FES
FLOWLINE ELEV. = 5020.90
EXISTING FES
FLOWLINE ELEV. = 5021.04
EXISTING OUTLET STRUCTURE
FLOWLINE ELEV. = 5022.75
EXISTING CHASE
EXISTING PAN
EXISTING PAN
EXISTING CHASE EXISTING CHASE
12" RCP
18" RCP
EXISTING NORTH DETENTION POND
(REFERENCES MADE TO THIS IN
DRAINAGE REPORT)
EXISTING SOUTH DETENTION POND
(REFERENCES MADE TO THIS IN
DRAINAGE REPORT)
Sheet
NEC LAKE AND SHIELDS 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
E NGINEER ING
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 07
C5.00
DRAINAGE EXHIBIT
07
NORTH
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
GRAPHIC SCALE:
City Engineer Date
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer
Date
Water & Wastewater Utility
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
Environmental Planner
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
LEGEND:
PROPOSED STORM SEWER
PROPOSED CURB & GUTTER
PROPERTY BOUNDARY
PROPOSED STORM INLET
EXISTING CURB & GUTTER
PROPOSED OVERLAND FLOW
EXISTING MAJOR CONTOUR
PROPOSED MAJOR CONTOUR
LID SUMMARY:
A2
a3
DRAINAGE BASIN AREA
DRAINAGE BASIN ID
DRAINAGE BASIN MINOR/MAJOR COEFF.
EXISTING STORM SEWER ST
PROPOSED DIRECT FLOW
BASIN DELINEATION
1. REFER TO "PRELIMINARY DRAINAGE REPORT FOR NEC LAKE AND SHIELDS"
PREPARED BY NORTHERN ENGINEERING ON 08/22/2018 FOR ADDITIONAL
INFORMATION.
NOTES:
BASIN
ID
TOTAL
AREA
(acres)
C2 C100
Q2
(cfs)
Q100
(cfs)
N1 0.425 0.60 0.75 0.70 3.15
S1 1.546 0.56 0.70 1.94 9.46
S2 0.067 0.95 1.00 0.18 0.66
OS1 0.131 0.23 0.29 0.09 0.38
RUNOFF SUMMARY:
Design
Point
Basin
ID
Basin
Impervio
us Area
(sq. ft.)
Treatment
Type
LID
System
Area
Treated
by LID
System
(sq. ft.)
Percent
of Site
Treated
by LID
System
n1 N1 10321 Standard
WQ No N/A 0%
s1 S1 34208 Rain
Garden Yes 34208 71%
s2 S2 2906 Rain
Garden Yes 2906 6%
OS1 600 Grass
Buffer No N/A 0%
Total 48035 37114 77%
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
=
12 hr
232-047 B. Mathisen
CSURF
0.1400 ac-ft
0.1400 ac-ft
North Pond
0.05
11
0.0000 ac-ft
5024.18 ft
North Pond Volume
Elevation
(ft)
n
1/4
0.007 sq-in
Circular Perforation Sizing
Dia (in.)
1
Calc.
Depths
( )
3
D * A 1 A 2 A 1 * A 2
V
= + +
232-047
NEC Lake and Shields
Project Number :
Project Name :
South Pond
Page 1 of 1
232-047_SouthPondDetentionVolume_FAAModified Method.xls
Per Row
Total Vol.
(ac-ft)
Total Vol.
(ft3)
Incremental
Vol. (ft3)
Incremental
Depth (ft)
Calc.
Depths
( )
3
D * A 1 A 2 A 1 * A 2
V
= + +
232-047
NEC Lake and Shields
Project Number :
Project Name :
North Pond
Page 1 of 1
232-047_NorthPondDetentionVolume_FAAModified Method.xls
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
n1 N1 No 0.60 0.60 0.75 100 4.50% 5.7 5.7 4.0 0 N/A N/A N/A 0 N/A N/A N/A 6 6 5
s1 S1 No 0.56 0.56 0.70 150 2.25% 9.5 9.5 7.1 0 N/A N/A N/A 0 N/A N/A N/A 10 10 7
s2 S2 No 0.95 0.95 1.00 150 2.00% 2.7 2.7 1.8 0 N/A N/A N/A 0 N/A N/A N/A 5 5 5
os1 OS1 No 0.23 0.23 0.29 75 17.00% 5.5 5.5 5.1 0 N/A N/A N/A 0 N/A N/A N/A 5 5 5
PROPOSED TIME OF CONCENTRATION COMPUTATIONS
B. Mathisen
Design
Point
Basin
Overland Flow Gutter Flow Swale Flow Time of Concentration
August 21, 2018
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
Page 2 of 21 D:\Projects\232-047\Drainage\Hydrology\232-047_Proposed Rational-Calcs.xlsx\Tc-2-yr_&_100-yr
= 1.00
**Soil Classification of site is Sandy Loam**
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.
Page 1 of 21 D:\Projects\232-047\Drainage\Hydrology\232-047_Proposed Rational-Calcs.xlsx\Proposed C-Values
C100
Q = C f ( C )( i )( A )
Page 3 of 20 D:\Projects\232-047\Drainage\Hydrology\232-047_Existing Rational-Calcs.xlsx\Hist-Direct-Runoff
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
ex-1 EX-1 No 0.17 0.17 0.21 181 3.31% 15.8 15.8 15.0 0 N/A N/A N/A 0 N/A N/A N/A 16 16 15
ex-2 EX-2 No 0.39 0.39 0.48 85 3.88% 7.8 7.8 6.8 0 N/A N/A N/A 0 N/A N/A N/A 8 8 7
ex-3 EX-3 No 0.38 0.38 0.47 196 2.04% 14.9 14.9 12.9 0 N/A N/A N/A 0 N/A N/A N/A 15 15 13
ex-4 EX-4 No 0.29 0.29 0.36 218 2.06% 17.6 17.6 16.0 0 N/A N/A N/A 0 N/A N/A N/A 18 18 16
ex-5 EX-5 No 0.48 0.48 0.60 63 3.17% 6.3 6.3 5.1 0 N/A N/A N/A 0 N/A N/A N/A 6 6 5
ex-6 EX-6 No 0.20 0.20 0.25 170 1.76% 18.2 18.2 17.2 0 N/A N/A N/A 0 N/A N/A N/A 18 18 17
ex-7 EX-7 No 0.43 0.43 0.54 77 3.90% 7.0 7.0 5.8 0 N/A N/A N/A 0 N/A N/A N/A 7 7 6
N/A
Existing Impervious
Area Breakdown No
0.82 0.82 1.00 181 3.31% 4.7 4.7 1.7 0 N/A N/A N/A 0 N/A N/A N/A 5 5 5
N/A
Existing Pervious Area
Breakdown No
0.15 0.15 0.19 22 4.23% 5.2 5.2 4.9 0 N/A N/A N/A 0 N/A N/A N/A 5 5 5
HISTORIC TIME OF CONCENTRATION COMPUTATIONS
B. Mathisen
Design
Point
Basin
Overland Flow Gutter Flow Swale Flow Time of Concentration
August 21, 2018
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
Page 2 of 20 D:\Projects\232-047\Drainage\Hydrology\232-047_Existing Rational-Calcs.xlsx\Hist-Tc-10-yr_&_100-yr
Area Breakdown 19883 0.46 0.07 0.02 0.24 0.13 0.00 0.82 0.82 1.00 77%
Existing Pervious
Area Breakdown 74567 1.71 0.00 0.00 0.00 0.00 1.71 0.15 0.15 0.19 0%
HISTORIC COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Notes
August 21, 2018
10-year Cf
= 1.00
**Soil Classification of site is Sandy Loam**
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.
Existing Impervious Area Breakdown
Page 1 of 20 D:\Projects\232-047\Drainage\Hydrology\232-047_Existing Rational-Calcs.xlsx\Hist-C-Values