HomeMy WebLinkAboutMOUNTAIN'S EDGE (FORMERLY 2430 OVERLAND TRAIL - RESIDENTIAL) - PDP - PDP160045 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTPRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT
February 14, 2017
Mountain’s Edge
Fort Collins, Colorado
Prepared for:
Lorson South Land Corp
Jeff Mark
212 N. Wahsatch Avenue, Suite 301
Colorado Springs, CO 80903
719-635-3200
Prepared by:
301 N. Howes Street, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158
www.northernengineering.com
Project Number: 911-007
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.
RE: Preliminary Drainage and Erosion Control Report for
Mountain’s Edge
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report for
your review. This report accompanies Project Development Plan submittal for the proposed
Mountain’s Edge 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.
Stephanie Thomas, PE
Project Engineer
Mountain’s Edge
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ....................................................................................................................................... 1
B. Description of Property ................................................................................................................ 1
C. Floodplain .................................................................................................................................... 3
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. Floodplain Regulations Compliance .............................................................................................. 6
G. Modifications of Criteria .............................................................................................................. 7
IV. DRAINAGE FACILITY DESIGN .................................................................................... 7
A. General Concept .......................................................................................................................... 7
B. Water Quality Treatment ........................................................................................................... 12
C. Specific Details ........................................................................................................................... 12
V. CONCLUSIONS ...................................................................................................... 13
A. Compliance with Standards ........................................................................................................ 13
B. Drainage Concept ...................................................................................................................... 13
References ....................................................................................................................... 14
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations (NOT INCLUDED WITH PDP)
B.1 – Detention Ponds and Water Quality
B.2 – Storm Sewers (NOT INCLUDED WITH PDP)
B.3 – Inlets (NOT INCLUDED WITH PDP)
APPENDIX C – Erosion Control Report
APPENDIX D – LID Exhibit
APPENDIX E - SWMM Modeling
APPENDIX F – References
Mountain’s Edge
Preliminary Drainage Report
LIST OF FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2– Proposed Site Plan ................................................................................................ 3
Figure 3 – Existing Floodplains ............................................................................................. 4
LIST OF TABLES:
Table 1 - Historic Rational Basin Summary ............................................................................ 8
Table 2 - Proposed Rational Basin Summary ........................................................................ 10
Table 3 - Detention Pond Summary ..................................................................................... 11
Table 4 - Historic Stormwater Release and Allowable Developed Release.................................. 11
Table 5 - Proposed Stormwater Release ............................................................................... 12
MAP POCKET:
HDR1 – Historic Drainage Exhibit
DR1 - Drainage Exhibit
Mountain’s Edge
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. A tract located in the southwest quarter of Section 21, Township 7 North, Range 69
West of the 6th Prime Meridian, City of Fort Collins, County of Larimer, State of
Colorado.
3. Bounded to the north by private property, to the west by Overland Trail, to the east by
the Brown Farm Subdivision, and to the south by Drake Road.
4. Significant offsite flows are directed into the site through Dixon Creek. Dixon Creek
traverses the Mountain’s Edge site within the southern half. Additionally, two existing
culverts cross Overland Trail. These culverts convey stormwater runoff from the
property to the west. These off-site flows will be conveyed safely to ultimate outfall
locations within the Mountain’s Edge site.
5. The Mountain’s Edge property has not been studied with the previous proposals or
drainage studies.
B. Description of Property
1. The site is approximately 19.67 acres. This acreage includes a portion of the adjacent
Overland Trail Right of Way.
Mountain’s Edge
Preliminary Drainage Report 2
Figure 1 – Aerial Photograph
2. The existing site is generally comprised of vacant land with natural grasses and
vegetation. A house, gravel drive, and out-structures exist on the site. Off-site basins
include portions of adjacent Overland Trail.
3. The north half of the site is within the Canal Importation Basin. The northern 1/3 of the
site slopes to the northern property line. A portion of the center of the site slopes to the
east and overland flows across the existing single-family lots. The southern half of the
site is located within the Spring Creek Basin and slopes south to the Dixon Creek
drainage channel.
4. A report by Soilogic dated June 11, 2015 lists the soils for the area as consisting of
silty/clayey sand, gravel, cobble and sandy lean clay ranging from 9 to 15 feet below the
ground surface. A Web Soil Survey by the Natural Resources Conservation Service
indicates soils are classified as Hydrologic Soil Group B and have a moderate infiltration
rate. For this study, the soils were modeled as a Soil Group C with a slow infiltration
rate to account for the soil variations within the soil borings.
5. The proposed project site plan is composed of 19 townhome buildings, 17 single-family
lots, public local streets, sidewalk, private asphalt drives, and detention ponds.
6. This site will employ water quality features and runoff reduction facilities including rain
gardens, minimization of directed connected areas of imperviousness, grass swales with
infiltration section, grass buffers, and extended detention basins.
Mountain’s Edge
Preliminary Drainage Report 3
Figure 2– Proposed Site Plan
7. No existing irrigation facilities are known at this time.
8. The project site has not been a part of any known previous drainage study.
C. Floodplain
1. The subject property is not located in a FEMA or City regulatory floodplain.
Mountain’s Edge
Preliminary Drainage Report 4
Figure 3 – Existing Floodplains
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The Mountain’s Edge project is located within two major drainage basins. The
northern half of the site is located within the Canal Importation Basin. The southern
half of the site is located within the Spring Creek Basin.
B. Sub-Basin Description
1. Historically, the stormwater runoff and off-site flows within the northern half of the
site generally flow in two directions. Stormwater runoff in the northern 1/3 of the site
generally flows to the northern boundary and is collected within a swale along the
access roadway on the adjacent property. Flows are conveyed to a channel in the
Brown’s Farm 3rd Subdivision. Stormwater within the remainder of the northern half
of the site overland flows across the existing single-family lots along the eastern
boundary of the site.
2. Historically, stormwater runoff within the southern half of the site overland flows to
the Dixon Creek channel. Once collected in the channel it is conveyed under Drake
Road and ultimately outfalling to Spring Creek.
3. The proposed plan will generally detain developed flows and release to the historical
Mountain’s Edge
Preliminary Drainage Report 5
outfall locations at the historical flow rates.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the Mountain’s Edge
project.
B. Four Step Process
The overall stormwater management strategy employed with the Mountain’s Edge 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:
Preserving natural areas south of the Dixon Creek. Minimizing site disturbance.
Proposed smaller private streets will allow for greater open space in the center of the
site. This approach allows for a lower percent imperviousness.
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 rain gardens, grass-lined channels or
grass buffers to provide additional infiltration.
Providing on-site detention to increase time of concentration, promote infiltration and
reduce loads on existing storm infrastructure.
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 majority of stormwater runoff from the site will ultimately be
intercepted and treated in proposed rain gardens and extended detention basins. Water
quality for areas not routed through the rain gardens will be provided within the extended
detention basin volume.
Step 3 – Stabilize Drainageways
This property discharges detained stormwater to an existing drainage channel (Dixon
Creek). The proposed release from this property is expected to require erosion control
mats to stabilize the drainage way at the proposed pipe outfalls. Additionally, any
proposed 4:1 grading will be required to be stabilized with erosion control blankets along
the Dixon Creek. The majority of the Dixon Creek channel will remain undisturbed.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
Trash receptacles within home will allow for the disposal of solid waste.
Rain Gardens and extended detention basins to provide for water treatment prior to
flows being released to existing drainageways and storm infrastructure.
Mountain’s Edge
Preliminary Drainage Report 6
Standard Operating Procedures (SOPs) for BMP maintenance of Rain Gardens,
Detention ponds, and associated drainage infrastructure to remove sediment
accumulation regularly.
C. Development Criteria Reference and Constraints
1. The proposed site is a part of the Spring Creek and Canal Importation Drainage
Basins. This basin requires a 2-year historic stormwater release from the developed
property.
2. This site is subject to the LID requirements per the City of Fort Collins. Please see the
LID Exhibit located in the Appendix for calculations concerning LID treatment. The
site must either have the following:
75% of total new impervious areas must be treated through an LID (Low Impact
Development) treatment BMP, or
50% of total new impervious areas must be treated through an LID (Low Impact
Development) treatment BMP and 25% of new pavement shall be pervious.
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 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. Modified FAA Method calculations were utilized for detention storage calculations.
4. Three separate design storms have been utilized to address distinct drainage
scenarios. The first event analyzed is the “Minor,” or “Initial” Storm, which has a 2-
year recurrence interval. The second event considered is the “Major Storm,” which
has a 100-year recurrence interval. The third 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 to the north and south.
2. All drainage facilities proposed with the Mountain’s Edge 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 previously, the subject property is not located within a FEMA regulatory
floodplain.
4. The Mountain’s Edge 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
floodplain, and thus are not subject to any floodplain regulations.
Mountain’s Edge
Preliminary Drainage Report 7
G. 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 Mountain’s Edge drainage design are to maintain the
allowable storm runoffs as outlined within both the Spring Creek and Canal
Importation Basin master plans, and to maintain the historic discharge locations.
2. Per the development guidelines, half of any existing adjacent roadway is required to
be detained and treated on-site, as is feasible and reasonable. With this
development, half of Overland Trail (north of Bluegrass) is proposed to be detained
and treated within the Mountain’s Edge project. Overland Trail (south of Bluegrass)
and Drake Road are adjacent to the site, but are not adjacent to the planned
development. As such, detention and treatment of these areas will be significantly
challenging. In order to meet this guideline, extensive storm infrastructure and
disturbance of existing vegetation would be required. With this in mind, these areas
of Overland Trail (south of Bluegrass) and Drake Road are not proposed to be
detained and treated on the Mountain’s Edge site.
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. Historic runoff from the Mountain’s Edge project site was evaluated. This evaluation
provided the historic 2-yr and 100-yr peak runoff rates for the existing site and
historic discharge locations.
Basin HA
Basin HA is generally the southern half of the property. Stormwater within this portion
of the existing property generally flows via overland to Dixon Creek, from there it is
conveyed to Spring Creek through existing drainage infrastructure. Basin HA is within
the Spring Creek Basin.
Basin HA was subdivided into 3 sub-basins to further aid in design.
Basin HA1 contains the area of the site that will remain mostly undisturbed and
pervious. This area includes Dixon Creek.
Basin HA2 contains area north of Dixon Creek that will be developed with this project.
Basin HA3 contains existing Overland Trail Right of Way proposed to be detained and
treated with this project.
Basin HB
Basin HB is generally the northern half of the property. Stormwater within this portion
of the existing property generally flows via overland the existing single-family
development or to a swale adjacent the existing access road, north of the property
boundary. These stormwater flows are conveyed through existing drainage
infrastructure to the detention ponds within the Brown’s Farm Subdivision. Basin HB
is within the Canal Importation Basin.
Mountain’s Edge
Preliminary Drainage Report 8
Basin HB was subdivided into 3 sub-basins to further aid in design.
Basin HB1 contains the northern 1/3 of the property. This area generally drains to the
northern property line and is collected in a swale along the off-site access road. From
there, flows are conveyed to a City owned and maintained drainage easement through
the Brown’s Farm Subdivision.
Basin HB2 contains existing Overland Trail Right of Way proposed to be detained and
treated with this project.
Basin HB3 contains a portion of the property that generally flows via overland to the
eastern boundary. Stormwater from this location historically flows through the
adjacent single-family lots to Compass Court.
Table 1 - Historic Rational Basin Summary
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 HA1 4.07 0.25 0.31 14.3 13.9 1.96 8.68
1 HA2 4.18 0.25 0.31 31.8 29.9 1.31 5.95
1 HA3 0.33 0.57 0.71 24.0 19.4 0.27 1.33
2 HB1 5.60 0.25 0.31 21.4 20.3 2.18 9.80
2 HB2 0.47 0.57 0.71 15.9 13.5 0.49 2.29
3 HB3 4.66 0.25 0.31 37.2 34.5 1.32 6.06
5. The Mountain’s Edge project divided the site into six (6) major drainage basins,
designated as Basins A, B, C, D, OS and UD. The drainage patterns anticipated for
each basin and sub-basin are further described below.
Basin A
Basin A consists of proposed single-family attached buildings, single-family lots,
sidewalk, roadways, landscape areas and Detention Pond 1. Basin A is subdivided
into 3 sub-basins (A1-A3). Runoff from Basins A1-A3 is detained in Detention Pond
1. Stormwater runoff within Basin A2 is treated for water quality and LID in Rain
Garden 1. Stormwater runoff from Basin A1 and A3 is treated for water quality within
Detention Pond 1. LID treatment for Basin A3 is provided through grass swales with
infiltration section.
Basin B
Basin B consists of proposed single-family attached buildings, single-family lots,
sidewalk, roadways, landscape areas and Detention Pond 2. Basin B is subdivided
into 5 sub-basins (B1-B5). Runoff from Basins B1-B5 is detained in Detention Pond
2. Stormwater runoff for Basins B1-B5 will be treated for water quality within
Detention Pond 2. Stormwater runoff from Basins B1, B2 and B5 is treated for LID
through grass-lined swales with infiltration section. Off-site stormwater from Basin
OS2 is conveyed in an existing culvert under Overland Trail. These flows will be
passed safely through Basin B1and Detention Pond 2 undetained.
Mountain’s Edge
Preliminary Drainage Report 9
Basin C
Basin C consists of proposed single-family attached buildings, sidewalk, roadways,
landscape areas and Detention Pond 3. Basin C is subdivided into 2 sub-basins (C1-
C2). Runoff from Basins C1-C2 is detained in Detention Pond 3. Stormwater runoff
for Basins C1-C2 will be treated for water quality within Detention Pond 3. Basin C2
will be treated for LID with grass swales with infiltration section. Off-site stormwater
from an existing culvert under Overland Trail, within Basin C1, will be safely routed
through Detention Pond 3 undetained. The off-site basin contributing to this culvert is
relatively small and contributions to any proposed storm infrastructure is expected to
be minimal.
Basin D
Basin D consists of proposed single-family attached buildings, single-family lots,
sidewalk, roadways, landscape areas and Detention Pond 4. Basin D is subdivided
into 5 sub-basins (D1-D5). Runoff from Basins D1-D5 is detained in Detention Pond
4. Stormwater runoff for Basins D1-D5 will be treated for water quality and LID
within Rain Garden 2. No additional water quality treatment is planned within
Detention Pond 4.
Basin UD
Basin UD1 consists of proposed sidewalk and roadways. Runoff from Basin UD1 will
not be detained. Stormwater runoff for Basin UD1 generally will be conveyed through
existing roadways within the Brown’s Farm Subdivision. No LID treatment is planned
for Basin UD1.
Basin UD2 consists of open space and Dixon Creek. No detention is proposed for this
basin as it is not being developed and generally will remain undisturbed. Minor
grading is proposed within this basin.
Basin OS
Basin OS1 is an off-site basin that consists of the existing drive-in theater. This basin
is generally a dirt parking lot with a paved access drive. Existing stormwater flows
from this site are directed toward the back lots lines of the Brown’s Farm Subdivsion.
An improved drainage channel is shown along the back lot lines in order to direct off-
site flows to the existing drainage channel on within Brown’s Farm.
Basin OS2 is an off-site basin west of Overland Trail. This basin stretches to west to
Horsetooth Reservoir. Based on existing topography, this basin was determined to be
approximately 14.7 acres. During a 100-year event, stormwater from this basin will
be conveyed to a culvert passing under Overland Trail within Basin B1. A SWMM
model was utilized to determine the maximum flow that would pass through the
existing culvert during a 100-year event. The maximum flow was determined to be
16.2 cfs with ponding west of Overland Trail. This flow will be safely passed through
Basin B and Detention Pond 2.
Basin OS3 is an off-site basin west of Overland Trail. This basin stretches to west to
the Dixon Creek Reservoir. This off-site basin contributes to Dixon Creek. Based on
the Fort Collins SWMM model for the Spring Creek Basin, this basin was determined
to be approximately 72.2 acres minus 8.58 acres of historic on-site basin, for a total
63.62 acres. During a 100-year event, stormwater from this basin will be conveyed
Mountain’s Edge
Preliminary Drainage Report 10
to an existing 18” culvert passing under Overland Trail within Basin UD2. The full
100-year flow is restricted by the 18” culvert and stormwater will pool west of
Overland Trail. At a depth approximately 6 feet above the culvert invert, the water will
bypass the culvert and continue south down a roadside swale on the west side of
Overland Trail. A SWMM model was utilized to determine the maximum flow that
would pass through the existing culvert during a 100-year event. The maximum flow
was determined to be 22.0 cfs with 18 cfs continuing south along Overland Trail.
Table 2 - Proposed Rational Basin Summary
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 A1 1.74 0.64 0.80 7.3 5.6 2.81 13.43
2 A2 2.24 0.75 0.94 5.0 5.0 4.80 20.96
3 A3 1.46 0.39 0.49 10.1 9.3 1.26 5.73
4 B1 0.47 0.83 1.00 6.2 5.0 1.03 4.63
5 B2 0.57 0.57 0.71 6.2 5.3 0.86 4.01
6 B3 1.27 0.84 1.00 5.0 5.0 3.04 12.67
7 B4 0.23 0.65 0.81 6.1 5.0 0.39 1.83
8 B5 1.31 0.28 0.35 12.6 11.9 0.74 3.35
9 C1 0.36 0.65 0.81 5.0 5.0 0.67 2.91
10 C2 0.48 0.40 0.50 6.1 5.4 0.52 2.40
11 D1 0.33 0.85 1.00 5.9 5.0 0.76 3.24
11 D2 1.71 0.67 0.84 5.0 5.0 3.28 14.34
12 D3 0.98 0.72 0.90 6.3 5.0 1.87 8.73
13 D4 0.66 0.59 0.73 5.1 5.0 1.10 4.81
14 D5 1.38 0.36 0.45 9.9 9.2 1.11 4.92
15 UD1 0.05 0.85 1.00 5.0 5.0 0.13 0.52
16 UD2 4.07 0.26 0.33 14.2 13.7 2.04 9.07
17 OS1 17.23 0.32 0.40 36.2 32.5 6.34 29.84
18 OS2 14.72 0.32 0.40 23.7 23.2 6.95 30.62
6. Four (4) detention ponds are proposed with the Mountain’s Edge development. These
ponds will restrict all runoff from the site to historic 2-yr flowrate based on the master
drainage basins, Spring Creek Basin and Canal Importation Basin.
Detention Pond 1
Detention Pond 1 detains developed runoff from Basin A. Detention Pond 1 has a
total 3.34 feet of freeboard from the 100-yr WSEL to the lowest proposed top of
foundation. Additionally, the emergency spill location is 1.58 feet below the lowest
proposed top of foundation. Water Quality is proposed within the pond volume
through an approved outlet structure.
Detention Pond 2
Detention Pond 2 detains developed runoff from Basin B. All minimum opening
Mountain’s Edge
Preliminary Drainage Report 11
Detention Pond 3
Detention Pond 3 detains developed runoff from Basin C. Detention Pond 3 has a
total 3.05 feet of freeboard from the 100-yr WSEL to the lowest proposed top of
foundation. The emergency spill for Pond 3 will be directed through an emergency
spill weir designed with final design. Water Quality is proposed within the pond
volume through an approved outlet structure. Additionally, Pond 3 will be designed to
pass off-site flow safely through the pond undetained.
Detention Pond 4
Detention Pond 4 detains developed runoff from Basin D. Detention Pond 4 has a
total 2.33 feet of freeboard from the 100-yr WSEL to the lowest proposed top of
foundation. The emergency spill for Pond 4 will be directed through an emergency
spill weir designed with final design. Water Quality is provided upstream of the
detention pond within Rain Garden 2.
Table 3 - Detention Pond Summary
Detention Pond Summary | Proposed Condition
Pond
100-yr
Volume
(ac-ft)
100-yr
WSEL
WQCV
(ft3)
WQCV WSEL
Max
Release
(cfs)
1 1.30 5144.99 2,506 5142.41 0.20
2 0.47 5138.97 2,991 5136.89 3.40
3 0.14 5145.23 495 5143.13 0.20
4 1.00 5142.43 n/a n/a 0.80
Total Stormwater Release from Site
The total allowable 100-yr release from the site was evaluated based on historic
Basins HA and HB. These basins correlate with the Spring Creek Basin and Canal
Importation Basin, respectively. The allowable release for the Spring Creek Basin is a
summation of the 100-yr historic runoff from Basin HA1 and the 2-yr historic runoff
from Basins HA2 and HA3. The allowable release for the Canal Importation Basin is a
summation of the 2-yr historic runoff from Basins HB1-HB3.
Table 4 - Historic Stormwater Release and Allowable Developed Release
Historic Stormwater Release
Allowable
Developed 100-
yr Release (cfs)
Pond/ Basin
2-yr Flow
(cfs)
100-yr Flow
(cfs)
HA1 1.96 8.68 8.68
HA2 1.31 5.95 1.31
HA3 0.27 1.33 0.27
TOTAL BASIN
HA 3.54 15.96 10.26
HB1 2.18 9.80 2.18
HB2 0.49 2.29 0.49
HB3 1.32 6.06 1.32
TOTAL BASIN
HB 3.99 18.15 3.99
Mountain’s Edge
Preliminary Drainage Report 12
Total developed 100-yr release in to the Spring Creek Basin (Historic Basin HA) is a
summation of the release rates from Ponds 1, 3, and 4, and the 100-yr flowrate for
Basin UD2. Total developed 100-yr release in to the Canal Importation Basin
(Historic Basin HB) is a summation of the release rate from Pond 2, and the 100-yr
flowrate for Basin UD1.
Table 5 - Proposed Stormwater Release
Proposed Stormwater Release
Pond/ Basin
100-yr Flow
(cfs)
Basin HA
Pond 1 0.20
Pond 3 0.20
Pond 4 0.80
Basin UD2 9.07
Total Basin HA 10.27
Basin HB
Pond 2 3.40
UD1 0.52
Total Basin HB 3.92
The proposed ponds will generally detain all developed flows from the property to the
2-year historic release for both the Spring Creek and Canal Importation Basins. An
additional 0.01 cfs is shown to be released to the Spring Creek Basin. This is
considered minimal and is expected to have no negative effects on downstream
drainage infrastructure.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this report.
B. Water Quality Treatment
1. A combination of 12-hr Rain Gardens and 40-hr Extended Detention Basins will
provide water quality for the site, including a portion of the Overland Trail right of
way.
2. Water Quality within the Detention Ponds will be provided through approved outlet
structures.
C. Specific Details
1. Additional details to be provided with the FDP submittal.
Mountain’s Edge
Preliminary Drainage Report 13
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the Mountain’s Edge project complies with the
City of Fort Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with the Mountain’s Edge project complies with the
City of Fort Collins’ Master Drainage Plan for the Spring Creek Basin and Canal
Importation Basin.
3. There are no regulatory floodplains associated with the development.
4. The drainage plan and stormwater management measures proposed with the
development are compliant with all applicable State and Federal regulations governing
stormwater discharge.
5. The site achieves LID treatment for 72% of total impervious areas. This is 3% less
than the requirements set forth by the City of Fort Collins for Low Impact
Development (LID). Due to site grading constraints and rules regarding LID treatment
of private development within City of Fort Collins Right of Way, full compliance was
unable to be achieved. Please see LID Exhibit located in the Appendix.
B. Drainage Concept
1. The drainage design proposed with this project will effectively comply with the Fort
Collins Master Drainage Plan and will limit any potential damage or erosion
associated with its stormwater runoff. All existing downstream drainage facilities are
expected to not be impacted negatively by this development
2. The drainage design is anticipated to be very conservative. We have omitted any
runoff reduction that will manifest due to infiltration within rain gardens and grass
swales. This is currently unable to be calculated with available soils data.
Mountain’s Edge
Preliminary Drainage Report 14
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. Preliminary Geotechnical Subsurface Exploration Report Proposed Single-Family Residential
Development Herring Property – 2430 South Overland Trail, Fort Collins, Colorado, June 11,
2015, Soilogic, Inc. (Soilogic Project No. 15-1132).
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
Mountain's Edge
CHARACTER OF SURFACE
1
:
Runoff
Coefficient
Percentage
Impervious Project: Mountain's Edge
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: S. Thomas
Asphalt ……....……………...……….....…...……………….………………………………………………………….0.95 . 100% Date: December 20, 2016
Concrete …….......……………….….……….………………..….…………………………………………………….0.95 . 90%
Gravel (packed) ……….…………………….….…………………………..………………………………………….0.50 . 40%
Roofs …….…….………………..……………….……………………………………………………………………… 0.95 90%
Pavers…………………………...………………..……………………………………………………………………… 0.40 22%
Lawns and Landscaping
Sandy Soil
Flat <2% ……………………………………………………………………………………………………………… 0.10 0%
Average 2% to 7% ………………………………………………………………………………………………….0.15 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.20 0%
Clayey Soil
Flat <2% ……………………………………………………………………………………………………………… 0.20 0%
Average 2% to 7% ………………………………………………………………………………………………….0.25 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.35 0% 2-year Cf = 1.00 10-year Cf = 1.00 100-year Cf = 1.25
Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Table RO-11
Sub-Basin ID
Sub-
BasinBasin
Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Pavers
(ac)
Area of
Roofs
(ac)
Soil Type and Average
Slope
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite Runoff
Coefficient
100-year
Composite Runoff
Coefficient
Composite
% Imperv.
HA1 4.07 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 4.075 0.25 0.25 0.31 0%
Mountain's Edge
Overland Flow, Time of Concentration:
Mountain's Edge
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)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
1 HA1 No 0.25 0.25 0.31 87 11.64% 6.5 6.5 6.1 681 0.94% 1.46 7.8 14.3 14.3 13.9
1 HA2 Yes 0.25 0.25 0.31 547 3.21% 25.2 25.2 23.4 583 0.96% 1.47 6.6 31.8 31.8 29.9
1 HA3 Yes 0.57 0.57 0.71 620 2.89% 17.4 17.4 12.8 583 0.96% 1.47 6.6 24.0 24.0 19.4
2 HB1 No 0.25 0.25 0.31 252 5.17% 14.6 14.6 13.5 590 0.94% 1.45 6.8 21.4 21.4 20.3
2 HB2 No 0.57 0.57 0.71 252 5.17% 9.1 9.1 6.7 590 0.94% 1.45 6.8 15.9 15.9 13.5
Mountain's Edge
Rational Method Equation: Project: Mountain's Edge
Calculations By:
Date:
Rainfall Intensity:
1 HA1 4.07 14 14 14 0.25 0.25 0.31 1.92 3.29 6.82 1.96 3.35 8.68
1 HA2 4.18 32 32 30 0.25 0.25 0.31 1.26 2.14 4.56 1.31 2.24 5.95
1 HA3 0.33 24 24 19 0.57 0.57 0.71 1.48 2.52 5.75 0.27 0.47 1.33
2 HB1 5.60 21 21 20 0.25 0.25 0.31 1.56 2.67 5.60 2.18 3.74 9.80
2 HB2 0.47 16 16 13 0.57 0.57 0.71 1.84 3.14 6.92 0.49 0.83 2.29
3 HB3 4.66 37 37 34 0.25 0.25 0.31 1.13 1.93 4.16 1.32 2.25 6.06
EXISTING 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)
Sub-Basin(s)
S. Thomas
Rainfall Intensity taken from the Fort Collins Stormwater Criteria Manual (FCSCM), Tables RA-7 and RA-8
December 20, 2016
Intensity,
i10
(in/hr)
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
Q = C f ( C )( i )( A )
12/20/2016 3:48 PM D:\Projects\911-007\Drainage\Hydrology\911-007_Existing_Rational_Calcs.xlsx\Runoff
Mountain's Edge
CHARACTER OF SURFACE
1
:
Runoff
Coefficient
Percentage
Impervious Project: Mountain's Edge
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: S. Thomas
Asphalt ……....……………...……….....…...……………….………………………………………………………….0.95 . 100% Date: February 13, 2017
Concrete …….......……………….….……….………………..….…………………………………………………….0.95 . 90%
Gravel (packed) ……….…………………….….…………………………..………………………………………….0.50 . 40%
Roofs …….…….………………..……………….……………………………………………………………………… 0.95 90%
Single Family Lots 0.30 30%
Lawns and Landscaping
Sandy Soil
Flat <2% ……………………………………………………………………………………………………………… 0.10 0%
Average 2% to 7% ………………………………………………………………………………………………….0.15 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.20 0%
Clayey Soil
Flat <2% ……………………………………………………………………………………………………………… 0.20 0%
Average 2% to 7% ………………………………………………………………………………………………….0.25 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.35 0% 2-year Cf = 1.00 10-year Cf = 1.00 100-year Cf = 1.25
Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Table RO-11
Sub-Basin ID
Sub-
BasinBasin
Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Single-Family
Lots
(ac)
Area of
Roofs
(ac)
Soil Type and Average
Slope
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite Runoff
Coefficient
100-year
Composite Runoff
Coefficient
Composite
% Imperv.
Mountain's Edge
Overland Flow, Time of Concentration:
Mountain's Edge
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
(min)
Mountain's Edge
Rational Method Equation: Project: Mountain's Edge
Calculations By:
Date:
Rainfall Intensity:
1 A1 1.74 7 7 6 0.64 0.64 0.80 2.52 4.31 9.63 2.81 4.81 13.43
2 A2 2.24 5 5 5 0.75 0.75 0.94 2.85 4.87 9.95 4.80 8.21 20.96
3 A3 1.46 10 10 9 0.39 0.39 0.49 2.21 3.78 8.03 1.26 2.16 5.73
3 TOTAL BASIN A 5.44 8 8 7 0.62 0.62 0.77 2.46 4.21 9.06 8.30 14.18 38.17
4 B1 0.47 6 6 5 0.83 0.83 1.00 2.67 4.56 9.95 1.03 1.76 4.63
5 B2 0.57 6 6 5 0.57 0.57 0.71 2.67 4.56 9.95 0.86 1.47 4.01
6 B3 1.27 5 5 5 0.84 0.84 1.00 2.85 4.87 9.95 3.04 5.20 12.67
7 B4 0.23 6 6 5 0.65 0.65 0.81 2.67 4.56 9.95 0.39 0.67 1.83
8 B5 1.31 13 13 12 0.28 0.28 0.35 2.02 3.45 7.29 0.74 1.26 3.35
8 TOTAL BASIN B 3.84 11 11 10 0.60 0.60 0.74 2.13 3.63 7.88 4.88 8.31 22.55
9 C1 0.36 5 5 5 0.65 0.65 0.81 2.85 4.87 9.95 0.67 1.14 2.91
10 C2 0.48 6 6 5 0.40 0.40 0.50 2.67 4.56 9.95 0.52 0.88 2.40
10 TOTAL BASIN C 0.85 5 5 5 0.50 0.50 0.63 2.85 4.87 9.95 1.22 2.08 5.31
11 D1 0.33 6 6 5 0.85 0.85 1.00 2.76 4.72 9.95 0.76 1.30 3.24
11 D2 1.71 5 5 5 0.67 0.67 0.84 2.85 4.87 9.95 3.28 5.61 14.34
12 D3 0.98 6 6 5 0.72 0.72 0.90 2.67 4.56 9.95 1.87 3.20 8.73
13 D4 0.66 5 5 5 0.59 0.59 0.73 2.85 4.87 9.95 1.10 1.88 4.81
14 D5 1.38 10 10 9 0.36 0.36 0.45 2.26 3.86 8.03 1.11 1.89 4.92
14 TOTAL BASIN D 5.05 11 11 9 0.60 0.60 0.74 2.17 3.71 8.03 6.53 11.14 30.19
15 UD1 0.05 5 5 5 0.85 0.85 1.00 2.85 4.87 9.95 0.13 0.21 0.52
16 UD2 4.07 14 14 14 0.26 0.26 0.33 1.92 3.29 6.82 2.04 3.50 9.07
17 OS1 17.23 36 36 32 0.32 0.32 0.40 1.15 1.96 4.33 6.34 10.81 29.84
18 OS2 14.72 24 24 23 0.32 0.32 0.40 1.48 2.52 5.20 6.95 11.87 30.62
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
PROPOSED 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)
Sub-Basin(s)
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 DETENTION POND SIZING
B.2 STORM SEWER (NOT INCLUDED)
B.3 INLET (NOT INCLUDED)
APPENDIX B.1
DETENTION PONDS AND WATER QUALITY
Mountain's Edge
911-007
Fort Collins, Colorado
S. Thomas Date: 2/13/2017
Pond No.: 1
Pond 1
100-yr
0.77 WQCV 2506 ft3
Area (A)= 5.44 acres Quantity Detention 54053 ft3
Max Release Rate = 0.2 cfs Total Volume 56559 ft3
Total Volume 1.298 ac-ft
Time Time
Fort Collins
100-yr Intensity
Q100
Inflow
(Runoff)
Volume
Outflow
(Release) Volume
Storage
Detention
Volume
(mins) (secs) (in/hr) (cfs) (ft3) (ft3) (ft3)
5 300 9.95 41.7 12504 60 12444
10 600 7.72 32.3 19403 120 19283
15 900 6.52 27.3 24580 180 24400
20 1200 5.60 23.5 28149 240 27909
25 1500 4.98 20.9 31290 300 30990
30 1800 4.52 18.9 34080 360 33720
35 2100 4.08 17.1 35890 420 35470
40 2400 3.74 15.7 37599 480 37119
45 2700 3.46 14.5 39132 540 38592
50 3000 3.23 13.5 40589 600 39989
55 3300 3.03 12.7 41884 660 41224
60 3600 2.86 12.0 43128 720 42408
65 3900 2.72 11.4 44435 780 43655
70 4200 2.59 10.8 45566 840 44726
75 4500 2.48 10.4 46747 900 45847
80 4800 2.38 10.0 47853 960 46893
85 5100 2.29 9.6 48921 1020 47901
90 5400 2.21 9.3 49989 1080 48909
95 5700 2.13 8.9 50856 1140 49716
100 6000 2.06 8.6 51774 1200 50574
105 6300 2.00 8.4 52779 1260 51519
110 6600 1.94 8.1 53633 1320 52313
115 6900 1.89 7.9 54626 1380 53246
120 7200 1.84 7.7 55493 1440 54053
Detention Pond Calculation | FAA Method
Project Number:
Project Location:
Calculations By:
Input Variables Results
Design Point
Design Storm Required Detention Volume
Developed "C" =
2/13/2017 7:16 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 1.xlsm\FAA_LarmCnty idf
Mountain's Edge
911-007
Fort Collins, CO
S. Thomas Date: 2/13/2017
Pond No.: 1
Pond 1
WQCV
2506 ft3 5142.41 ft.
Design Storm 100-yr
Required Volume= 56559 ft3 5144.99 ft.
Contour
Elevation (Y-
values)
Contour
Area
Depth
Incremental Area
Avg. End
Cumulative Volume
Avg. End
Incremental Volume
Conic
Cummulative
Volume Conic (X-
values)
ft3 ft. ft3 ft3 ft3 ft3
5,141.60 196 0.00 0 0 0 0
5,141.80 1084 0.20 128 128 116 116
5,142.00 2642 0.20 373 501 361 477
5,142.20 4699 0.20 734 1235 724 1202
5,142.40 7382 0.20 1208 2443 1198 2400
5,142.60 10397 0.20 1778 4221 1769 4169
5,142.80 13236 0.20 2363 6584 2358 6527
5,143.00 15745 0.20 2898 9482 2894 9421
5,143.20 17952 0.20 3370 12852 3367 12788
5,143.40 19,800 0.20 3775 16627 3774 16562
5,143.60 21,376 0.20 4118 20745 4117 20679
5,143.80 22,862 0.20 4424 25168 4423 25101
5,144.00 24,087 0.20 4695 29863 4694 29796
5,144.20 25,287 0.20 4937 34801 4937 34733
5,144.40 26,412 0.20 5170 39971 5169 39902
5,144.60 27,517 0.20 5393 45364 5392 45295
5,144.80 28,603 0.20 5612 50976 5612 50906
5,145.00 29,445 0.20 5805 56780 5805 56711
5,145.20 30,301 0.20 5975 62755 5974 62686
5,145.40 31,206 0.20 6151 68906 6151 68836
Design Point
Design Storm
Require Volume=
Stage - Storage Calculation
Project Number:
Project Location:
Calculations By:
Required Volume Water Surface Elevation (WSE)
2/13/20177:16 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 1.xlsm\Stage_Storage
POND 1
Project: Mountain's Edge
By: S. Thomas
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA (acres)= 5.440 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 52.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.5200 <-- CALCULATED
Drain Time (hrs) 40 <-- INPUT
Drain Time Coefficient 1.0 <-- CALCULATED from Figure Table 3-2
WQCV (watershed inches) = 0.212 <-- CALCULATED from Figure 3-2
WQCV (ac-ft) = 0.096 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
Rain Garden WQCV (ft
3
) = 1676 <-- CALCULATED
Adjusted WQCV (cu-ft) = 2506 <-- CALCULATED (minus Rain Garden)
WQ Depth (ft) = 1.000 <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in
2
) = 0.235 <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = 5/9 <-- INPUT from Figure 5
number of rows = 3
t (in) = 0.500 <-- INPUT from Figure 5
number of columns = 1.000 <-- CALCULATED from WQ Depth and row spacing
WATER QUALITY CONTROL STRUCTURE PLATE
February 11, 2017
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 66.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.660
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.21 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 97,422 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 1,676 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 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 = 1286 sq ft
D) Actual Flat Surface Area AActual = 1469 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 3989 sq ft
F) Rain Garden Total Volume VT= 2,729 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 = 2.0 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 1,676 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 1 in
Design Procedure Form: Rain Garden (RG)
Stephanie Thomas
Northern Engineering
February 13, 2017
Mountain's Edge - Rain Garden 1
Drake and Overland, Fort Collins, CO
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
Rain Garden 1.xlsm, RG 2/13/2017, 7:15 AM
Slotted underdrain will
provided, no orifice is required
per FC guidelines
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
NO SPRINKLER HEADS ON FLAT SURFACE
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Stephanie Thomas
Northern Engineering
February 13, 2017
Mountain's Edge - Rain Garden 1
Drake and Overland, Fort Collins, CO
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
Rain Garden 1.xlsm, RG 2/13/2017, 7:15 AM
Mountain's Edge
911-007
Fort Collins, Colorado
S. Thomas Date: 2/13/2017
Pond No.: Pond 2
Pond 2
100-yr
0.74 WQCV 2991 ft3
Area (A)= 3.84 acres Quantity Detention 17366 ft3
Max Release Rate = 3.4 cfs Total Volume 20357 ft3
Total Volume 0.467 ac-ft
Time Time
Fort Collins
100-yr Intensity
Q100
Inflow
(Runoff)
Volume
Outflow
(Release) Volume
Storage
Detention
Volume
(mins) (secs) (in/hr) (cfs) (ft3) (ft3) (ft3)
5 300 9.95 28.3 8482 1020 7462
10 600 7.72 21.9 13162 2040 11122
15 900 6.52 18.5 16675 3060 13615
20 1200 5.60 15.9 19096 4080 15016
25 1500 4.98 14.2 21227 5100 16127
30 1800 4.52 12.8 23119 6120 16999
35 2100 4.08 11.6 24347 7140 17207
40 2400 3.74 10.6 25506 8160 17346
45 2700 3.46 9.8 26546 9180 17366
50 3000 3.23 9.2 27535 10200 17335
55 3300 3.03 8.6 28413 11220 17193
60 3600 2.86 8.1 29257 12240 17017
65 3900 2.72 7.7 30144 13260 16884
70 4200 2.59 7.4 30911 14280 16631
75 4500 2.48 7.0 31712 15300 16412
80 4800 2.38 6.8 32462 16320 16142
85 5100 2.29 6.5 33187 17340 15847
90 5400 2.21 6.3 33912 18360 15552
95 5700 2.13 6.1 34500 19380 15120
100 6000 2.06 5.9 35122 20400 14722
105 6300 2.00 5.7 35804 21420 14384
110 6600 1.94 5.5 36384 22440 13944
115 6900 1.89 5.4 37057 23460 13597
120 7200 1.84 5.2 37646 24480 13166
Detention Pond Calculation | FAA Method
Project Number:
Project Location:
Calculations By:
Input Variables Results
Design Point
Design Storm Required Detention Volume
Developed "C" =
2/13/2017 7:17 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 2.xlsm\FAA_LarmCnty idf
Mountain's Edge
911-007
Fort Collins, CO
S. Thomas Date: 2/13/2017
Pond No.: Pond 2
Pond 2
WQCV
2991 ft3 5136.89 ft.
Design Storm 100-yr
Required Volume= 20357 ft3 5138.97 ft.
Contour
Elevation (Y-
values)
Contour
Area
Depth
Incremental Area
Avg. End
Cumulative Volume
Avg. End
Incremental Volume
Conic
Cummulative
Volume Conic (X-
values)
ft3 ft. ft3 ft3 ft3 ft3
5,135.80 30 0.00 0 0 0 0
5,136.00 619 0.20 65 65 52 52
5,136.20 1747 0.20 237 302 227 279
5,136.40 3046 0.20 479 781 473 753
5,136.60 4335 0.20 738 1519 734 1487
5,136.80 5443 0.20 978 2497 976 2463
5,137.00 6188 0.20 1163 3660 1162 3625
5,137.20 6758 0.20 1295 4954 1294 4919
5,137.40 7212 0.20 1397 6351 1397 6316
5,137.60 7646 0.20 1486 7837 1486 7802
5,137.80 8080 0.20 1573 9410 1572 9374
5,138.00 8518 0.20 1660 11070 1660 11034
5,138.20 8957 0.20 1747 12817 1747 12781
5,138.40 9393 0.20 1835 14652 1835 14616
5,138.60 9823 0.20 1922 16574 1921 16537
5,138.80 10249 0.20 2007 18581 2007 18544
5,139.00 10672 0.20 2092 20673 2092 20636
5,139.20 11094 0.20 2177 22849 2176 22812
5,139.40 11532 0.20 2263 25112 2262 25075
Design Point
Design Storm
Require Volume=
Stage - Storage Calculation
Project Number:
Project Location:
Calculations By:
Required Volume Water Surface Elevation (WSE)
2/13/20177:17 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 2.xlsm\Stage_Storage
POND 2
Project: Mountain's Edge
By: S. Thomas
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA (acres)= 3.840 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 53.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.5300 <-- CALCULATED
Drain Time (hrs) 40 <-- INPUT
Drain Time Coefficient 1.0 <-- CALCULATED from Figure Table 3-2
WQCV (watershed inches) = 0.215 <-- CALCULATED from Figure 3-2
WQCV (ac-ft) = 0.069 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
Rain Garden WQCV (ft
3
) = 0 <-- CALCULATED
Adjusted WQCV (cu-ft) = 2991 <-- CALCULATED (minus Rain Garden)
WQ Depth (ft) = 1.090 <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in
2
) = 0.271 <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = 3/5 <-- INPUT from Figure 5
number of rows = 3
t (in) = 0.500 <-- INPUT from Figure 5
number of columns = 1.000 <-- CALCULATED from WQ Depth and row spacing
WATER QUALITY CONTROL STRUCTURE PLATE
February 11, 2017
Mountain's Edge
911-007
Fort Collins, Colorado
S. Thomas Date: 2/13/2017
Pond No.: Pond 3
Pond 3
100-yr
0.63 WQCV 495 ft3
Area (A)= 0.85 acres Quantity Detention 5654 ft3
Max Release Rate = 0.2 cfs Total Volume 6149 ft3
Total Volume 0.141 ac-ft
Time Time
Larimer County
Area II
100-yr Intensity
Q100
Inflow
(Runoff)
Volume
Outflow
(Release) Volume
Storage
Detention
Volume
(mins) (secs) (in/hr) (cfs) (ft3) (ft3) (ft3)
5 300 9.95 5.3 1598 60 1538
10 600 7.72 4.1 2480 120 2360
15 900 6.52 3.5 3142 180 2962
20 1200 5.60 3.0 3599 240 3359
25 1500 4.98 2.7 4000 300 3700
30 1800 4.52 2.4 4357 360 3997
35 2100 4.08 2.2 4588 420 4168
40 2400 3.74 2.0 4807 480 4327
45 2700 3.46 1.9 5003 540 4463
50 3000 3.23 1.7 5189 600 4589
55 3300 3.03 1.6 5354 660 4694
60 3600 2.86 1.5 5514 720 4794
65 3900 2.72 1.5 5681 780 4901
70 4200 2.59 1.4 5825 840 4985
75 4500 2.48 1.3 5976 900 5076
80 4800 2.38 1.3 6118 960 5158
85 5100 2.29 1.2 6254 1020 5234
90 5400 2.21 1.2 6391 1080 5311
95 5700 2.13 1.1 6502 1140 5362
100 6000 2.06 1.1 6619 1200 5419
105 6300 2.00 1.1 6747 1260 5487
110 6600 1.94 1.0 6857 1320 5537
115 6900 1.89 1.0 6983 1380 5603
120 7200 1.84 1.0 7094 1440 5654
Detention Pond Calculation | FAA Method
Project Number:
Project Location:
Calculations By:
Input Variables Results
Design Point
Design Storm Required Detention Volume
Developed "C" =
2/13/2017 7:18 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 3.xlsm\FAA_LarmCnty idf
Mountain's Edge
911-007
Fort Collins, CO
S. Thomas Date: 2/13/2017
Pond No.: Pond 3
Pond 3
WQCV
495 ft3 5143.13 ft.
Design Storm 100-yr
Required Volume= 6149 ft3 5145.23 ft.
Contour
Elevation (Y-
values)
Contour
Area
Depth
Incremental Area
Avg. End
Cumulative Volume
Avg. End
Incremental Volume
Conic
Cummulative
Volume Conic (X-
values)
ft3 ft. ft3 ft3 ft3 ft3
5,142.00 9 0.00 0 0 0 0
5,142.20 73 0.20 8 8 7 7
5,142.40 199 0.20 27 35 26 33
5,142.60 389 0.20 59 94 58 91
5,142.80 640 0.20 103 197 102 193
5,143.00 955 0.20 160 357 158 352
5,143.20 1,336 0.20 229 586 228 580
5,143.40 1,746 0.20 308 894 307 887
5,143.60 1,900 0.20 365 1259 364 1251
5,143.80 2,062 0.20 396 1655 396 1647
5,144.00 2,266 0.20 433 2088 433 2080
5,144.20 2,522 0.20 479 2566 478 2559
5,144.40 2,828 0.20 535 3101 535 3093
5,144.60 3,185 0.20 601 3703 601 3694
5,144.80 3,592 0.20 678 4380 677 4371
5,145.00 4,049 0.20 764 5144 764 5135
5,145.20 4,569 0.20 862 6006 861 5996
5,145.40 5,182 0.20 975 6981 974 6971
Design Point
Design Storm
Require Volume=
Stage - Storage Calculation
Project Number:
Project Location:
Calculations By:
Required Volume Water Surface Elevation (WSE)
2/13/20177:19 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 3.xlsm\Stage_Storage
POND 3
Project: Mountain's Edge
By: S. Thomas
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA (acres)= 0.850 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 33.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.3300 <-- CALCULATED
Drain Time (hrs) 40 <-- INPUT
Drain Time Coefficient 1.0 <-- CALCULATED from Figure Table 3-2
WQCV (watershed inches) = 0.161 <-- CALCULATED from Figure 3-2
WQCV (ac-ft) = 0.011 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
Rain Garden WQCV (ft
3
) = 0 <-- CALCULATED
Adjusted WQCV (cu-ft) = 495 <-- CALCULATED (minus Rain Garden)
WQ Depth (ft) = 1.130 <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in
2
) = 0.049 <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = 1/4 <-- INPUT from Figure 5
number of rows = 3
t (in) = 0.500 <-- INPUT from Figure 5
number of columns = 1.000 <-- CALCULATED from WQ Depth and row spacing
WATER QUALITY CONTROL STRUCTURE PLATE
February 11, 2017
Mountain's Edge
911-007
Fort Collins, Colorado
S. Thomas Date: 2/13/2017
Pond No.: 4
Pond 4
100-yr
0.74 WQCV 0 ft3
Area (A)= 5.05 acres Quantity Detention 43748 ft3
Max Release Rate = 0.8 cfs Total Volume 43748 ft3
Total Volume 1.004 ac-ft
Time Time
Fort Collins
100-yr Intensity
Q100
Inflow
(Runoff)
Volume
Outflow
(Release) Volume
Storage
Detention
Volume
(mins) (secs) (in/hr) (cfs) (ft3) (ft3) (ft3)
5 300 9.95 37.2 11155 240 10915
10 600 7.72 28.8 17310 480 16830
15 900 6.52 24.4 21929 720 21209
20 1200 5.60 20.9 25113 960 24153
25 1500 4.98 18.6 27915 1200 26715
30 1800 4.52 16.9 30404 1440 28964
35 2100 4.08 15.2 32019 1680 30339
40 2400 3.74 14.0 33543 1920 31623
45 2700 3.46 12.9 34911 2160 32751
50 3000 3.23 12.1 36212 2400 33812
55 3300 3.03 11.3 37366 2640 34726
60 3600 2.86 10.7 38476 2880 35596
65 3900 2.72 10.2 39642 3120 36522
70 4200 2.59 9.7 40651 3360 37291
75 4500 2.48 9.3 41705 3600 38105
80 4800 2.38 8.9 42691 3840 38851
85 5100 2.29 8.6 43644 4080 39564
90 5400 2.21 8.3 44597 4320 40277
95 5700 2.13 8.0 45371 4560 40811
100 6000 2.06 7.7 46189 4800 41389
105 6300 2.00 7.5 47086 5040 42046
110 6600 1.94 7.2 47849 5280 42569
115 6900 1.89 7.1 48734 5520 43214
120 7200 1.84 6.9 49508 5760 43748
Input Variables Results
Design Point
Design Storm Required Detention Volume
Developed "C" =
Detention Pond Calculation | FAA Method
Project Number:
Project Location:
Calculations By:
2/13/2017 11:00 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 4.xlsm\FAA_LarmCnty idf
Mountain's Edge
911-007
Fort Collins, CO
S. Thomas Date: 2/13/2017
Pond No.: 4
Pond 4
WQCV
0 ft3 5136.60 ft.
Design Storm 100-yr
Required Volume= 43748 ft3 5142.43 ft.
Contour
Elevation (Y-
values)
Contour
Area
Depth
Incremental Area
Avg. End
Cumulative Volume
Avg. End
Incremental Volume
Conic
Cummulative
Volume Conic (X-
values)
ft3 ft. ft3 ft3 ft3 ft3
5,136.60 66 0.00 0 0 0 0
5,136.80 410 0.20 48 48 43 43
5,137.00 857 0.20 127 174 124 167
5,137.20 1333 0.20 219 393 217 384
5,137.40 1832 0.20 316 710 315 699
5,137.60 2,207 0.20 404 1114 403 1102
5,137.80 2,554 0.20 476 1590 476 1578
5,138.00 2,924 0.20 548 2138 547 2126
5,138.20 3,279 0.20 620 2758 620 2746
5,138.40 3,530 0.20 681 3439 681 3426
5,138.60 3,787 0.20 732 4171 732 4158
5,138.80 4,059 0.20 785 4955 784 4942
5,139.00 4,344 0.20 840 5795 840 5782
5,139.20 4,642 0.20 899 6694 898 6681
5,139.40 6,397 0.20 1104 7798 1099 7780
5,139.60 6,892 0.20 1329 9127 1329 9109
5,139.80 7,414 0.20 1431 10557 1430 10539
5,140.00 7,957 0.20 1537 12094 1537 12075
5,140.20 8,522 0.20 1648 13742 1648 13723
5,140.40 9,110 0.20 1763 15505 1763 15486
5,140.60 9,725 0.20 1884 17389 1883 17369
5,140.80 13,580 0.20 2331 19720 2320 19689
5,141.00 14,614 0.20 2819 22539 2819 22508
5,141.20 15,718 0.20 3033 25572 3032 25540
5,141.40 12,761 0.20 2848 28420 2843 28383
5,141.60 13,565 0.20 2633 31053 2632 31015
5,141.80 14,408 0.20 2797 33850 2797 33812
5,142.00 15,302 0.20 2971 36821 2970 36783
5,142.20 16,263 0.20 3156 39977 3156 39939
5,142.40 17,301 0.20 3356 43334 3356 43294
5,142.60 18,413 0.20 3571 46905 3571 46865
5,142.80 19,593 0.20 3801 50706 3800 50665
5,143.00 20,830 0.20 4042 54748 4042 54707
Design Point
POND 4
Project: Mountain's Edge
By: S. Thomas
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA (acres)= 5.050 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 52.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.5200 <-- CALCULATED
Drain Time (hrs) 40 <-- INPUT
Drain Time Coefficient 0.8 <-- CALCULATED from Figure Table 3-2
WQCV (watershed inches) = 0.169 <-- CALCULATED from Figure 3-2
WQCV (ac-ft) = 0.071 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
Rain Garden WQCV (ft
3
) = 3104 <-- CALCULATED
Adjusted WQCV (cu-ft) = 0 <-- CALCULATED (minus Rain Garden)
WQ Depth (ft) = 1.000 <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in
2
) = 0.000 <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = 0 <-- INPUT from Figure 5
number of rows = 3
t (in) = 0.500 <-- INPUT from Figure 5
number of columns = 1.000 <-- CALCULATED from WQ Depth and row spacing
WATER QUALITY CONTROL STRUCTURE PLATE
February 11, 2017
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 52.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.520
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.17 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 219,874 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 3,104 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 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 = 16 in 12-INCH MAXIMUM
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 = 2287 sq ft
D) Actual Flat Surface Area AActual = 1446 sq ft ACTUAL FLAT AREA < MINIMUM FLAT AREA
E) Area at Design Depth (Top Surface Area) ATop = 3365 sq ft
F) Rain Garden Total Volume VT= 3,207 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 = 2.0 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 3,104 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 1 2/7 in
Design Procedure Form: Rain Garden (RG)
Stephanie Thomas
Northern Engineering
February 13, 2017
Mountain's Edge - Rain Garden 2
Drake and Overland, Fort Collins CO
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
Rain Garden 2.xlsm, RG 2/13/2017, 7:15 AM
Slotted underdrain will
provided, no orifice is required
per FC guidelines
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)
Stephanie Thomas
Northern Engineering
February 13, 2017
Mountain's Edge - Rain Garden 2
Drake and Overland, Fort Collins CO
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
Rain Garden 2.xlsm, RG 2/13/2017, 7:15 AM
APPENDIX B.2
STORM SEWERS
APPENDIX B.3
INLETS
APPENDIX C
EROSION CONTROL REPORT
Mountain’s Edge
Preliminary 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 Sheet CS2 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 D
LID EXHIBIT
Project: Mountain's Edge
Calculations By: S. Thomas
Date: February 13, 2017
LID BASIN NODE Sub-Basin(s)
Area, A
(sf)
Percent
Impervious
Impervious Area,
A
(sf)
LID Treatment
L1 A2 97,422 66% 64,148 Rain Garden 1
A3 63,689
18% 11,513
Grass-Lined Swale w/
Infiltration Section
Total L1 161,111 47% 75,661
L2 B1 20,289 82% 16,641
B2 24,873 41% 10,081
B5 56,915 21% 12,156
Total L2 102,077 38% 38,878
L3 C2 21,094 19% 4,027
Total L3 21,094 19% 4,027
L4 D1 14,166 85% 12,078
D2 74,422 62% 45,999
D3 42,668 64% 27,116
D4 28,680 60% 17,322
D5 59,938 20% 12,171
Total L4 219,874 52% 114,686
Total Treated 504,156 46% 233,251
LID BASIN NODE Sub-Basin(s)
Area, A
(sf)
Percent
Impervious
Impervious Area,
A
(sf)
A1 75,924 63% 47,926
B3 55,488 78% 43,280
B4 9,903 64% 6,346
C1 15,762 51% 8,046
UD1 2,263 83% 1,872
Total Proposed
Untreated
159,340 67% 107,471
HA3 14,166 45% 6,375
HB2 20,289 45% 9,130
Total Existing 34,455 45% 15,505
Grass-Lined Swale w/
Infilatration Section
PROPOSED LID COMPUTATIONS
PROPOSED LID UNTREATED AREA
PROPOSED LID TREATED AREA
Rain Garden 2
Grass-Lined Swale w/
Infiltration Section
Project: Mountain's Edge
Calculations By: S. Thomas
Date: February 13, 2017
PROPOSED LID COMPUTATIONS
663,496
15,505
340,721
325,216
243,912
233,251
72%
Rain Garden 1 Rain Garden 2
Total Contributing
Area (sf)
97,422 219,874
Percent Impervious 66% 52%
Total Volume
Required (cf)
1,676 3,104
Total Volume
Provided (cf)
1,676 3,104
RAIN GARDEN SUMMARY
LID TREATMENT SUMMARY
Total Site Area (sf)
Total Existing Impervious Area (sf)
Total Proposed Impervious Area (sf)
Total Treated Impervious Area (sf)
Percent Impervious Treated by LID
measures
75% Required Minimum Area to be
Treated by LID measures (sf)
Total Net Proposed Impervious Area (sf)
APPENDIX E
SWMM Modeling
SUB-A
SUB-B
SUB-C
SUB-D
OS1
OS2 OS3
SUB-UD2
1
2
3
8
9
BYPASS
OUT1
OUT2
OUT3
OUT4
OUTOS2
OUTOS3
J1
J2
J3
J4
J5
O1
O2
O3
POND1
POND2
POND3
POND4
PONDOS2
PONDOS3
FORTCOLLINS100YR
03/15/2016 00:05:00
SWMM 5.1 Page 1
Mountains Edge - SWMM 100yr.inp
[TITLE]
;;Project Title/Notes
[OPTIONS]
;;Option Value
FLOW_UNITS CFS
INFILTRATION HORTON
FLOW_ROUTING KINWAVE
LINK_OFFSETS DEPTH
MIN_SLOPE 0
ALLOW_PONDING NO
SKIP_STEADY_STATE NO
START_DATE 03/15/2016
START_TIME 00:00:00
REPORT_START_DATE 03/15/2016
REPORT_START_TIME 00:00:00
END_DATE 03/15/2016
END_TIME 06:00:00
SWEEP_START 01/01
SWEEP_END 12/31
DRY_DAYS 0
REPORT_STEP 00:05:00
WET_STEP 00:05:00
DRY_STEP 01:00:00
ROUTING_STEP 0:00:15
INERTIAL_DAMPING PARTIAL
NORMAL_FLOW_LIMITED BOTH
FORCE_MAIN_EQUATION H-W
VARIABLE_STEP 0.75
LENGTHENING_STEP 0
MIN_SURFAREA 12.557
Page 1
Mountains Edge - SWMM 100yr.inp
MAX_TRIALS 8
HEAD_TOLERANCE 0.005
SYS_FLOW_TOL 5
LAT_FLOW_TOL 5
MINIMUM_STEP 0.5
THREADS 1
[EVAPORATION]
;;Data Source Parameters
;;-------------- ----------------
CONSTANT 0.0
DRY_ONLY NO
[RAINGAGES]
;;Name Format Interval SCF Source
;;-------------- --------- ------ ------ ----------
FORTCOLLINS100YR INTENSITY 0:05 1.0 TIMESERIES 100-YR
[SUBCATCHMENTS]
;;Name Rain Gage Outlet Area %Imperv Width %Slope CurbLen
SnowPack
;;-------------- ---------------- ---------------- -------- -------- -------- -------- --------
----------------
SUB-A FORTCOLLINS100YR POND1 5.44 52 4739 2 0
SUB-B FORTCOLLINS100YR POND2 3.84 53 3350 2 0
SUB-C FORTCOLLINS100YR POND3 .85 33 740 2 0
SUB-D FORTCOLLINS100YR POND4 5.05 52 4400 2 0
OS1 FORTCOLLINS100YR J4 17.23 10 750 2 0
Page 2
Mountains Edge - SWMM 100yr.inp
OS2 FORTCOLLINS100YR PONDOS2 14.72 10 1000 2 0
OS3 FORTCOLLINS100YR PONDOS3 63.62 10 3000 2 0
SUB-UD2 FORTCOLLINS100YR J2 4.07 25 1772 2 0
[SUBAREAS]
;;Subcatchment N-Imperv N-Perv S-Imperv S-Perv PctZero RouteTo PctRouted
;;-------------- ---------- ---------- ---------- ---------- ---------- ---------- ----------
SUB-A .016 .25 .1 .3 0 OUTLET
SUB-B .016 .25 .1 .3 0 OUTLET
SUB-C .016 .25 .1 .3 0 OUTLET
SUB-D .016 .25 .1 .3 0 OUTLET
OS1 .016 .25 .1 .3 0 OUTLET
OS2 .016 .25 .1 .3 0 OUTLET
OS3 .016 .25 .1 .3 0 OUTLET
SUB-UD2 .016 .25 .1 .3 0 OUTLET
[INFILTRATION]
;;Subcatchment MaxRate MinRate Decay DryTime MaxInfil
;;-------------- ---------- ---------- ---------- ---------- ----------
SUB-A 3.0 0.5 4 7 0
SUB-B 3.0 0.5 4 7 0
SUB-C 3.0 0.5 4 7 0
SUB-D 3.0 0.5 4 7 0
OS1 3.0 0.5 4 7 0
OS2 3.0 0.5 4 7 0
OS3 3.0 0.5 4 7 0
SUB-UD2 3.0 0.5 4 7 0
[JUNCTIONS]
;;Name Elevation MaxDepth InitDepth SurDepth Aponded
Page 3
Mountains Edge - SWMM 100yr.inp
;;-------------- ---------- ---------- ---------- ---------- ----------
J1 40.7 5 0 0 0
J2 39.1 5 0 0 0
J3 34.2 5 0 0 0
J4 38.22 3 0 0 0
J5 45.6 3 0 0 0
[OUTFALLS]
;;Name Elevation Type Stage Data Gated Route To
;;-------------- ---------- ---------- ---------------- -------- ----------------
O1 35.5 FREE NO
O2 33.6 FREE NO
O3 48 FREE NO
[STORAGE]
;;Name Elev. MaxDepth InitDepth Shape Curve Name/Params N/A
Fevap Psi Ksat IMD
;;-------------- -------- ---------- ----------- ---------- ---------------------------- --------
-------- -------- --------
POND1 41.6 4 .8 TABULAR POND1 0 0
POND2 35.8 4 1.09 TABULAR POND2 0 0
POND3 42 4 1.13 TABULAR POND3 0 0
POND4 36.6 6.5 .8 TABULAR POND4 0 0
PONDOS2 47 7 0 TABULAR PONDOS2 0 0
PONDOS3 44 7 0 TABULAR PONDOS3 0 0
[CONDUITS]
Page 4
Mountains Edge - SWMM 100yr.inp
;;Name From Node To Node Length Roughness InOffset OutOffset
InitFlow MaxFlow
;;-------------- ---------------- ---------------- ---------- ---------- ---------- ----------
---------- ----------
1 J1 J2 300 .025 0 0 0
0
2 J2 J3 300 .025 0 0 0
0
3 J3 O2 100 .025 0 0 0
0
8 J5 J4 400 .025 0 0 0
0
9 J4 O1 155 .025 0 0 0
0
[WEIRS]
;;Name From Node To Node Type CrestHt Qcoeff Gated
EndCon EndCoeff Surcharge RoadWidth RoadSurf
;;-------------- ---------------- ---------------- ------------ ---------- ---------- --------
-------- ---------- ---------- ---------- ----------
BYPASS PONDOS3 O3 TRANSVERSE 6 3.33 NO 0
0 YES
[OUTLETS]
;;Name From Node To Node Offset Type QTable/Qcoeff
Qexpon Gated
;;-------------- ---------------- ---------------- ---------- --------------- ----------------
---------- --------
OUT1 POND1 J2 0 TABULAR/DEPTH POND1ORIFICE
NO
OUT2 POND2 O1 0 TABULAR/DEPTH POND2ORIFICE
NO
OUT3 POND3 J1 0 TABULAR/DEPTH POND3ORIFICE
Page 5
Mountains Edge - SWMM 100yr.inp
NO
OUT4 POND4 J3 0 TABULAR/DEPTH POND4ORIFICE
NO
OUTOS2 PONDOS2 J5 0 TABULAR/DEPTH PONDOS2ORIFICE
NO
OUTOS3 PONDOS3 J1 0 TABULAR/DEPTH PONDOS3ORIFICE
NO
[XSECTIONS]
;;Link Shape Geom1 Geom2 Geom3 Geom4 Barrels Culvert
;;-------------- ------------ ---------------- ---------- ---------- ---------- ----------
----------
1 TRIANGULAR 5 40 0 0 1
2 TRIANGULAR 5 40 0 0 1
3 TRIANGULAR 5 40 0 0 1
8 TRIANGULAR 1 24 0 0 1
9 TRIANGULAR 3 24 0 0 1
BYPASS RECT_OPEN 1 100 0 0
[CURVES]
;;Name Type X-Value Y-Value
;;-------------- ---------- ---------- ----------
POND1ORIFICE Rating 0 0
POND1ORIFICE 3.3 .2
POND1ORIFICE 3.8 .23
;
POND2ORIFICE Rating 0 0
Page 6
Mountains Edge - SWMM 100yr.inp
POND2ORIFICE 3.6 3.4
POND2ORIFICE 4 3.8
;
POND3ORIFICE Rating 0 0
POND3ORIFICE 3.2 .2
POND3ORIFICE 3.4 .22
;
POND4ORIFICE Rating 0 0
POND4ORIFICE 5.87 .8
POND4ORIFICE 6.4 .9
;
PONDOS2ORIFICE Rating 0.00 0.00
PONDOS2ORIFICE 0.50 11.76
PONDOS2ORIFICE 1.00 16.63
PONDOS2ORIFICE 1.50 20.37
PONDOS2ORIFICE 2.00 23.52
PONDOS2ORIFICE 2.50 26.30
PONDOS2ORIFICE 3.00 28.80
PONDOS2ORIFICE 3.50 31.11
PONDOS2ORIFICE 4.00 33.26
PONDOS2ORIFICE 4.50 35.28
PONDOS2ORIFICE 5.00 37.19
PONDOS2ORIFICE 5.50 39.00
PONDOS2ORIFICE 6.00 40.74
PONDOS2ORIFICE 6.50 42.40
PONDOS2ORIFICE 7.00 44.00
;
PONDOS3ORIFICE Rating 0.00 0.00
PONDOS3ORIFICE 0.50 6.35
PONDOS3ORIFICE 1.00 8.98
PONDOS3ORIFICE 1.50 11.00
PONDOS3ORIFICE 2.00 12.70
PONDOS3ORIFICE 2.50 14.20
Page 7
Mountains Edge - SWMM 100yr.inp
PONDOS3ORIFICE 3.00 15.56
PONDOS3ORIFICE 3.50 16.80
PONDOS3ORIFICE 4.00 17.96
PONDOS3ORIFICE 4.50 19.05
PONDOS3ORIFICE 5.00 20.08
PONDOS3ORIFICE 5.50 21.06
PONDOS3ORIFICE 6.00 22.00
;
POND1 Storage 0 195.82
POND1 0.2 1084.42
POND1 0.4 2641.83
POND1 0.6 4698.99
POND1 0.8 7382.11
POND1 1 10396.95
POND1 1.2 13235.5
POND1 1.4 15744.69
POND1 1.6 17951.92
POND1 1.8 19800.35
POND1 2 21376.02
POND1 2.2 22862.1
POND1 2.4 24087.47
POND1 2.6 25287.06
POND1 2.8 26411.82
POND1 3 27516.87
POND1 3.2 28603.07
POND1 3.4 29445.4
POND1 3.6 30300.87
POND1 3.8 31206.37
;
POND2 Storage 0 29.98
POND2 0.2 618.86
POND2 0.4 1747.49
POND2 0.6 3045.67
Page 8
Mountains Edge - SWMM 100yr.inp
POND2 0.8 4335.41
POND2 1 5442.92
POND2 1.2 6187.71
POND2 1.4 6757.69
POND2 1.6 7212.28
POND2 1.8 7645.63
POND2 2 8080.34
POND2 2.2 8517.69
POND2 2.4 8957.28
POND2 2.6 9392.94
POND2 2.8 9823.05
POND2 3 10248.93
POND2 3.2 10671.54
POND2 3.4 11093.73
POND2 3.6 11532.03
;
POND3 Storage 0 9.07
POND3 0.2 73.23
POND3 0.4 199.32
POND3 0.6 388.82
POND3 0.8 640.23
POND3 1 955.09
POND3 1.2 1335.94
POND3 1.4 1745.81
POND3 1.6 1900.27
POND3 1.8 2061.76
POND3 2 2265.69
POND3 2.2 2521.51
POND3 2.4 2828.3
POND3 2.6 3185.02
POND3 2.8 3591.72
POND3 3 4049.28
POND3 3.2 4569.41
Page 9
Mountains Edge - SWMM 100yr.inp
POND3 3.4 5181.81
;
POND4 Storage 0 65.77
POND4 0.2 410.36
POND4 0.4 857.42
POND4 0.6 1332.88
POND4 0.8 1831.52
POND4 1 2207.33
POND4 1.2 2554.41
POND4 1.4 2924
POND4 1.6 3278.84
POND4 1.8 3529.72
POND4 2 3787.15
POND4 2.2 4058.76
POND4 2.4 4343.84
POND4 2.6 4641.83
POND4 2.8 6397.24
POND4 3 6891.51
POND4 3.2 7413.64
POND4 3.4 7956.87
POND4 3.6 8521.85
POND4 3.8 9110.47
POND4 4 9725.39
POND4 4.2 13580.32
POND4 4.4 14613.97
POND4 4.6 15717.51
POND4 4.8 12761.36
POND4 5 13564.85
POND4 5.2 14407.69
POND4 5.4 15301.59
POND4 5.6 16262.69
POND4 5.8 17301.39
POND4 6 18412.79
Page 10
Mountains Edge - SWMM 100yr.inp
POND4 6.2 19593.12
;
PONDOS2 Storage 0 7453.84
PONDOS2 1 17466.34
PONDOS2 2 28633.01
PONDOS2 3 47631.06
PONDOS2 4 69976.41
PONDOS2 5 92755.43
PONDOS2 6 117217.13
PONDOS2 7 143723.75
;
PONDOS3 Storage 0 2031.79
PONDOS3 1 9775.88
PONDOS3 2 17701.44
PONDOS3 3 25195.74
PONDOS3 4 30910.42
PONDOS3 5 36766.41
PONDOS3 6 41957.84
PONDOS3 7 41957
[TIMESERIES]
;;Name Date Time Value
;;-------------- ---------- ---------- ----------
100-YR 0:05 1
100-YR 0:10 1.14
100-YR 0:15 1.33
100-YR 0:20 2.23
100-YR 0:25 2.84
100-YR 0:30 5.49
100-YR 0:35 9.95
100-YR 0:40 4.12
100-YR 0:45 2.48
100-YR 0:50 1.46
Page 11
Mountains Edge - SWMM 100yr.inp
100-YR 0:55 1.22
100-YR 1:00 1.06
100-YR 1:05 1
100-YR 1:10 .95
100-YR 1:15 .91
100-YR 1:20 .87
100-YR 1:25 .84
100-YR 1:30 .81
100-YR 1:35 .78
100-YR 1:40 .75
100-YR 1:45 .73
100-YR 1:50 .71
100-YR 1:55 .69
100-YR 2:00 .67
[REPORT]
;;Reporting Options
INPUT NO
CONTROLS NO
SUBCATCHMENTS ALL
NODES ALL
LINKS ALL
[TAGS]
[MAP]
DIMENSIONS -1395.210 0.000 11395.210 10000.000
Units None
[COORDINATES]
;;Node X-Coord Y-Coord
;;-------------- ------------------ ------------------
J1 7766.467 3508.982
Page 12
Mountains Edge - SWMM 100yr.inp
J2 8461.078 4946.108
J3 10077.844 7017.964
J4 -508.982 6491.018
J5 -401.198 2826.347
O1 -628.743 8095.808
O2 10161.677 7688.623
O3 10928.144 2347.305
POND1 4113.772 5365.269
POND2 556.886 7377.246
POND3 6269.461 3029.940
POND4 9191.617 7269.461
PONDOS2 329.341 1928.144
PONDOS3 7970.060 2107.784
[VERTICES]
;;Link X-Coord Y-Coord
;;-------------- ------------------ ------------------
9 -640.719 8179.641
BYPASS 10353.294 1976.048
[Polygons]
;;Subcatchment X-Coord Y-Coord
;;-------------- ------------------ ------------------
SUB-A 3251.497 5257.485
SUB-B 1035.928 6071.856
SUB-C 5646.707 3353.293
SUB-D 6437.126 5952.096
OS1 -1011.976 5616.766
OS2 377.246 946.108
OS3 8041.916 958.084
SUB-UD2 9455.090 4467.066
[SYMBOLS]
Page 13
Mountains Edge - SWMM 100yr.inp
;;Gage X-Coord Y-Coord
;;-------------- ------------------ ------------------
FORTCOLLINS100YR 1335.329 9161.677
[BACKDROP]
FILE "D:\Projects\911-007\Drainage\SWMM\911-007_DRNG DR1 (1).jpg"
DIMENSIONS -1395.210 1334.229 11395.210 8665.771
Page 14
Mountains Edge - SWMM 100yr.rpt
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.010)
--------------------------------------------------------------
*********************************************************
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 ............ MAR-15-2016 00:00:00
Ending Date .............. MAR-15-2016 06:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 00:05:00
Wet Time Step ............ 00:05:00
Dry Time Step ............ 01:00:00
Page 1
Mountains Edge - SWMM 100yr.rpt
Routing Time Step ........ 15.00 sec
************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 35.108 3.669
Evaporation Loss ......... 0.000 0.000
Infiltration Loss ........ 19.223 2.009
Surface Runoff ........... 15.860 1.658
Final Storage ............ 0.153 0.016
Continuity Error (%) ..... -0.365
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 15.860 5.168
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 13.879 4.523
Flooding Loss ............ 0.000 0.000
Evaporation Loss ......... 0.000 0.000
Exfiltration Loss ........ 0.000 0.000
Initial Stored Volume .... 0.153 0.050
Final Stored Volume ...... 2.131 0.694
Continuity Error (%) ..... 0.014
Page 2
Mountains Edge - SWMM 100yr.rpt
********************************
Highest Flow Instability Indexes
********************************
Link OUTOS2 (8)
Link OUTOS3 (6)
Link 9 (4)
Link 8 (3)
*************************
Routing Time Step Summary
*************************
Minimum Time Step : 15.00 sec
Average Time Step : 15.00 sec
Maximum Time Step : 15.00 sec
Percent in Steady State : 0.00
Average Iterations per Step : 1.00
Percent Not Converging : 0.00
***************************
Subcatchment Runoff Summary
***************************
--------------------------------------------------------------------------------------------------------
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
Page 3
Mountains Edge - SWMM 100yr.rpt
--------------------------------------------------------------------------------------------------------
SUB-A 3.67 0.00 0.00 0.92 2.75 0.41 48.53
0.749
SUB-B 3.67 0.00 0.00 0.90 2.77 0.29 34.43
0.754
SUB-C 3.67 0.00 0.00 1.29 2.40 0.06 6.77
0.654
SUB-D 3.67 0.00 0.00 0.92 2.75 0.38 45.06
0.749
OS1 3.67 0.00 0.00 2.24 1.42 0.67 26.13
0.388
OS2 3.67 0.00 0.00 2.10 1.56 0.63 26.35
0.427
OS3 3.67 0.00 0.00 2.22 1.45 2.51 99.12
0.395
SUB-UD2 3.67 0.00 0.00 1.47 2.21 0.24 24.37
0.601
******************
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
---------------------------------------------------------------------------------
J1 JUNCTION 0.99 1.31 42.01 0 02:07 1.31
J2 JUNCTION 1.00 1.31 40.41 0 02:08 1.31
Page 4
Mountains Edge - SWMM 100yr.rpt
J3 JUNCTION 1.06 1.57 35.77 0 00:41 1.51
J4 JUNCTION 0.44 1.25 39.47 0 00:41 1.23
J5 JUNCTION 0.21 0.61 46.21 0 01:02 0.61
O1 OUTFALL 0.43 1.25 36.75 0 00:41 1.23
O2 OUTFALL 1.06 1.56 35.16 0 00:41 1.52
O3 OUTFALL 0.00 0.00 48.00 0 00:00 0.00
POND1 STORAGE 3.00 3.36 44.96 0 02:10 3.36
POND2 STORAGE 2.03 3.60 39.40 0 01:05 3.60
POND3 STORAGE 2.87 3.33 45.33 0 02:07 3.33
POND4 STORAGE 5.19 5.97 42.57 0 02:09 5.97
PONDOS2 STORAGE 0.20 0.96 47.96 0 01:02 0.95
PONDOS3 STORAGE 3.22 6.15 50.15 0 01:37 6.15
*******************
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
-------------------------------------------------------------------------------------------------
J1 JUNCTION 0.00 22.21 0 02:07 0 2.25 0.000
J2 JUNCTION 24.37 37.61 0 00:40 0.244 2.53 0.000
J3 JUNCTION 0.00 37.58 0 00:41 0 2.64 0.000
J4 JUNCTION 26.13 35.57 0 00:41 0.666 1.29 0.000
J5 JUNCTION 0.00 16.20 0 01:02 0 0.625 0.000
O1 OUTFALL 0.00 38.23 0 00:42 0 1.6 0.000
O2 OUTFALL 0.00 37.52 0 00:41 0 2.64 0.000
Page 5
Mountains Edge - SWMM 100yr.rpt
O3 OUTFALL 0.00 18.83 0 01:37 0 0.281 0.000
POND1 STORAGE 48.53 48.53 0 00:40 0.406 0.424 -0.001
POND2 STORAGE 34.43 34.43 0 00:40 0.288 0.311 0.050
POND3 STORAGE 6.77 6.77 0 00:40 0.0554 0.0591 -0.001
POND4 STORAGE 45.06 45.06 0 00:40 0.377 0.382 -0.001
PONDOS2 STORAGE 26.35 26.35 0 00:40 0.626 0.626 0.067
PONDOS3 STORAGE 99.12 99.12 0 00:40 2.51 2.51 0.018
**********************
Node Surcharge Summary
**********************
Surcharging occurs when water rises above the top of the highest conduit.
---------------------------------------------------------------------
Max. Height Min. Depth
Hours Above Crown Below Rim
Node Type Surcharged Feet Feet
---------------------------------------------------------------------
J1 JUNCTION 6.00 1.314 3.686
J2 JUNCTION 6.00 1.314 3.686
J3 JUNCTION 6.00 1.566 3.434
J4 JUNCTION 6.00 1.254 1.746
J5 JUNCTION 6.00 0.609 2.391
POND1 STORAGE 6.00 3.355 0.645
POND2 STORAGE 6.00 3.604 0.396
POND3 STORAGE 6.00 3.332 0.668
POND4 STORAGE 6.00 5.972 0.528
PONDOS2 STORAGE 6.00 0.956 6.044
PONDOS3 STORAGE 6.00 6.147 0.853
Page 6
Mountains Edge - SWMM 100yr.rpt
*********************
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
--------------------------------------------------------------------------------------------------
POND1 46.963 62 0 0 55.472 74 0 02:10 0.20
POND2 11.045 37 0 0 25.158 84 0 01:04 3.40
POND3 4.932 46 0 0 6.637 62 0 02:07 0.21
POND4 36.615 64 0 0 46.385 82 0 02:08 0.82
PONDOS2 2.128 0 0 0 11.701 3 0 01:01 16.20
PONDOS3 64.696 35 0 0 148.527 81 0 01:37 40.83
***********************
Outfall Loading Summary
***********************
-----------------------------------------------------------
Flow Avg Max Total
Page 7
Mountains Edge - SWMM 100yr.rpt
Freq Flow Flow Volume
Outfall Node Pcnt CFS CFS 10^6 gal
-----------------------------------------------------------
O1 100.00 9.91 38.23 1.602
O2 99.93 16.35 37.52 2.640
O3 14.93 11.64 18.83 0.281
-----------------------------------------------------------
System 71.62 37.90 75.70 4.522
********************
Link Flow Summary
********************
-----------------------------------------------------------------------------
Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence |Veloc| Full Full
Link Type CFS days hr:min ft/sec Flow Depth
-----------------------------------------------------------------------------
1 CONDUIT 22.21 0 02:08 3.22 0.03 0.26
2 CONDUIT 37.00 0 00:41 5.58 0.03 0.26
3 CONDUIT 37.52 0 00:41 3.84 0.05 0.31
8 CONDUIT 16.20 0 01:03 3.65 0.27 0.61
9 CONDUIT 35.55 0 00:41 5.66 0.10 0.42
BYPASS WEIR 18.83 0 01:37 0.00
OUT1 DUMMY 0.20 0 02:10
OUT2 DUMMY 3.40 0 01:05
OUT3 DUMMY 0.21 0 02:07
OUT4 DUMMY 0.82 0 02:09
OUTOS2 DUMMY 16.20 0 01:02
OUTOS3 DUMMY 22.00 0 01:26
Page 8
Mountains Edge - SWMM 100yr.rpt
*************************
Conduit Surcharge Summary
*************************
No conduits were surcharged.
Analysis begun on: Mon Feb 13 10:32:15 2017
Analysis ended on: Mon Feb 13 10:32:15 2017
Total elapsed time: < 1 sec
Page 9
APPENDIX F
REFERENCES
Hydrologic Soil Group—Larimer County Area, Colorado
(Mountain's Edge)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/21/2016
Page 1 of 4
4489080 4489140 4489200 4489260 4489320 4489380 4489440 4489500 4489560
4489080 4489140 4489200 4489260 4489320 4489380 4489440 4489500 4489560
488580 488640 488700 488760 488820 488880 488940
488580 488640 488700 488760 488820 488880 488940
40° 33' 24'' N
105° 8' 5'' W
40° 33' 24'' N
105° 7' 50'' W
40° 33' 8'' N
105° 8' 5'' W
40° 33' 8'' N
105° 7' 50'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 100 200 400 600
Feet
0 35 70 140 210
Meters
Map Scale: 1:2,410 if printed on A portrait (8.5" x 11") sheet.
Warning: Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
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: http://websoilsurvey.nrcs.usda.gov
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 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
Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
3 Altvan-Satanta loams, 0
to 3 percent slopes
B 8.7 42.7%
4 Altvan-Satanta loams, 3
to 9 percent slopes
B 11.6 57.3%
Totals for Area of Interest 20.3 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive precipitation
from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly
wet. These consist mainly of deep, well drained to excessively drained sands or
gravelly sands. These soils have a high rate of water transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well drained
soils that have moderately fine texture to moderately coarse texture. These soils
have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of water
transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay layer
at or near the surface, and soils that are shallow over nearly impervious material.
These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in their
natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Hydrologic Soil Group—Larimer County Area, Colorado Mountain's Edge
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/21/2016
Page 3 of 4
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Larimer County Area, Colorado Mountain's Edge
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/21/2016
Page 4 of 4
MAP POCKET
DR1 – OVERALL DRAINAGE EXHIBIT
X
X
X
X
X
X
X
X
X
X
X
X X
X
X X X X
X
X
X
X
X X X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X X X X
X X
X
X
X
X X X X X X X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X X X
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
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
N O R T H E RN
PHONE: 970.221.4158
www.northernengineering.com
DR1
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what's
R
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
( IN FEET )
0
1 INCH = 60 FEET
60 60 120 180
LEGEND:
5013
PROPOSED CONTOUR 93
EXISTING CONTOUR
PROPERTY BOUNDARY
EXISTING STORM SEWER
1. THE SIZE, TYPE AND LOCATION OF ALL KNOWN UNDERGROUND UTILITIES ARE
APPROXIMATE WHEN SHOWN ON THESE DRAWINGS. IT SHALL BE THE
RESPONSIBILITY OF THE CONTRACTOR TO VERIFY THE EXISTENCE OF ALL
UNDERGROUND UTILITIES IN THE AREA OF THE WORK. BEFORE COMMENCING
NEW CONSTRUCTION, THE CONTRACTOR SHALL BE RESPONSIBLE FOR LOCATING
ALL UNDERGROUND UTILITIES AND SHALL BE RESPONSIBLE FOR FOR ALL
UNKNOWN UNDERGROUND UTILITIES.
2. REFER TO THE"Preliminary Drainage Report for Mountains Edge " BY NORTHERN
ENGINEERING, DATED February 14, 2017 FOR ADDITIONAL INFORMATION.
NOTES:
FLOW PATH
DRAINAGE BASIN BUBBLE
A
DESIGN POINT A
BASIN BOUNDARY
PROPOSED STORM SEWER
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
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 A1 1.74 0.64 0.80 7.3 5.6 2.81 13.43
2 A2 2.24 0.75 0.94 5.0 5.0 4.80 20.96
3 A3 1.46 0.39 0.49 10.1 9.3 1.26 5.73
4 B1 0.47 0.83 1.00 6.2 5.0 1.03 4.63
5 B2 0.57 0.57 0.71 6.2 5.3 0.86 4.01
6 B3 1.27 0.84 1.00 5.0 5.0 3.04 12.67
7 B4 0.23 0.65 0.81 6.1 5.0 0.39 1.83
8 B5 1.31 0.28 0.35 12.6 11.9 0.74 3.35
9 C1 0.36 0.65 0.81 5.0 5.0 0.67 2.91
10 C2 0.48 0.40 0.50 6.1 5.4 0.52 2.40
11 D1 0.33 0.85 1.00 5.9 5.0 0.76 3.24
11 D2 1.71 0.67 0.84 5.0 5.0 3.28 14.34
12 D3 0.98 0.72 0.90 6.3 5.0 1.87 8.73
13 D4 0.66 0.59 0.73 5.1 5.0 1.10 4.81
14 D5 1.38 0.36 0.45 9.9 9.2 1.11 4.92
15 UD1 0.05 0.85 1.00 5.0 5.0 0.13 0.52
16 UD2 4.07 0.26 0.33 14.2 13.7 2.04 9.07
17 OS1 17.23 0.32 0.40 36.2 32.5 6.34 29.84
18 OS2 14.72 0.32 0.40 23.7 23.2 6.95 30.62
Detention Pond Summary | Proposed Condition
Pond 100-yr Volume
(ac-ft)
100-yr WSEL WQCV
(ft3)
WQCV WSEL Max Release
(cfs)
1 1.30 5144.99 2,506 5142.41 0.20
2 0.47 5138.97 2,991 5136.89 3.40
3 0.14 5145.23 495 5143.13 0.20
4 1.00 5142.43 n/a n/a 0.80
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
/
/ / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / /
/ / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
/ / / / / / / / / / / / / / / /
GAS
MM
T
W
VAULT
F.O.
B M D
T C
F
E
S
C
ONTROL
IRR
S
H2O
H2O
H2O
20" W
20" W
20" W
20" W
20" W 20" W
20" W
20" W 20" W
20" W
20" W 20" W
20" W
20" W 20" W
20" W
20" W 20" W
16" W
16" W 16" W
16" W
16" W 16" W
16" W
16" W 16" W
HA1
HA2
HB1
HB2 HA3
1
2
HB3
3
8" SS
6" W
6" W 6" W
6" W 6" W 6" W 6" W 6" W 6" W 6" W
6" W
8" SS 8" SS
8" SS 8" SS 8" SS
8" SS 8" SS
6" W
6" W
S
6" W
S
S
OVERLAND TRAIL
BLUEGRASS DRIVE
DRAKE ROAD
Sheet
MOUNTAIN'S EDGE 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
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
E NGINEER ING
N O R T H E RN
PHONE: 970.221.4158
www.northernengineering.com
of 23
HDR1
HISTORIC DRAINAGE EXHIBIT
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
( IN FEET )
0
1 INCH = 60 FEET
60 60 120 180
LEGEND:
5013
PROPOSED CONTOUR 93
EXISTING CONTOUR
PROPERTY BOUNDARY
EXISTING STORM SEWER
1. THE SIZE, TYPE AND LOCATION OF ALL KNOWN UNDERGROUND UTILITIES ARE
APPROXIMATE WHEN SHOWN ON THESE DRAWINGS. IT SHALL BE THE
RESPONSIBILITY OF THE CONTRACTOR TO VERIFY THE EXISTENCE OF ALL
UNDERGROUND UTILITIES IN THE AREA OF THE WORK. BEFORE COMMENCING
NEW CONSTRUCTION, THE CONTRACTOR SHALL BE RESPONSIBLE FOR LOCATING
ALL UNDERGROUND UTILITIES AND SHALL BE RESPONSIBLE FOR FOR ALL
UNKNOWN UNDERGROUND UTILITIES.
2. REFER TO THE "PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT FOR
MOUNTAIN'S EDGE" BY NORTHERN ENGINEERING, DATED DECEMBER 20TH, 2016
FOR ADDITIONAL INFORMATION.
NOTES:
FLOW PATH
DRAINAGE BASIN BUBBLE
A
DESIGN POINT A
BASIN BOUNDARY
PROPOSED STORM SEWER
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
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 HA1 4.07 0.25 0.31 14.3 13.9 1.96 8.68
1 HA2 4.18 0.25 0.31 31.8 29.9 1.31 5.95
1 HA3 0.33 0.57 0.71 24.0 19.4 0.27 1.33
2 HB1 5.60 0.25 0.31 21.4 20.3 2.18 9.80
2 HB2 0.47 0.57 0.71 15.9 13.5 0.49 2.29
3 HB3 4.66 0.25 0.31 37.2 34.5 1.32 6.06
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales 1:50,000
or larger.
Date(s) aerial images were photographed: Apr 22, 2011—Apr 28,
2011
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.
Hydrologic Soil Group—Larimer County Area, Colorado
(Mountain's Edge)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/21/2016
Page 2 of 4
Design Storm
Require Volume=
Stage - Storage Calculation
Project Number:
Project Location:
Calculations By:
Required Volume Water Surface Elevation (WSE)
2/13/201711:00 AM D:\Projects\911-007\Drainage\Detention\911-007_Detention Pond 4.xlsm\Stage_Storage
S. Thomas
Rainfall Intensity taken from the Fort Collins Stormwater Criteria Manual (FCSCM), Tables RA-7 and RA-8
February 13, 2017
Intensity,
i10
(in/hr)
C10
Q = C f ( C )( i )( A )
2/13/2017 7:09 AM D:\Projects\911-007\Drainage\Hydrology\911-007_Proposed_Rational_Calcs.xlsx\Runoff
10-yr
Tc
(min)
100-yr
Tc
(min)
1 A1 No 0.64 0.64 0.80 61 2.34% 5.1 5.1 3.3 N/A N/A N/A 227 0.70% 1.67 2.3 7.3 7.3 5.6
2 A2 No 0.75 0.75 0.94 35 3.54% 2.5 2.5 1.1 N/A N/A N/A 249 0.80% 1.79 2.3 5.0 5.0 5.0
3 A3 No 0.39 0.39 0.49 69 7.35% 5.7 5.7 4.9 163 1.04% 1.53 1.8 264 0.68% 1.65 2.7 10.1 10.1 9.3
3 TOTAL BASIN A No 0.62 0.62 0.77 35 3.54% 3.5 3.5 2.4 163 1.04% 1.53 1.8 264 0.68% 1.65 2.7 7.9 7.9 6.8
4 B1 No 0.83 0.83 1.00 46 2.83% 2.4 2.4 0.9 N/A N/A N/A 358 0.63% 1.59 3.7 6.2 6.2 5.0
5 B2 No 0.57 0.57 0.71 47 10.83% 3.1 3.1 2.3 389 1.99% 2.11 3.1 N/A N/A N/A 6.2 6.2 5.3
6 B3 No 0.84 0.84 1.00 39 3.28% 2.1 2.1 0.8 N/A N/A N/A 349 1.45% 2.41 2.4 5.0 5.0 5.0
7 B4 No 0.65 0.65 0.81 60 2.62% 4.8 4.8 3.1 N/A N/A N/A 216 1.94% 2.79 1.3 6.1 6.1 5.0
8 B5 No 0.28 0.28 0.35 50 2.00% 8.6 8.6 7.9 311 2.41% 2.33 2.2 157 0.52% 1.44 1.8 12.6 12.6 11.9
8 TOTAL BASIN B No 0.60 0.60 0.74 46 2.83% 4.5 4.5 3.2 389 1.99% 2.11 3.1 358 0.63% 1.59 3.7 11.3 11.3 10.0
9 C1 No 0.65 0.65 0.81 35 5.14% 2.9 2.9 1.9 N/A N/A N/A 106 0.47% 1.37 1.3 5.0 5.0 5.0
10 C2 No 0.40 0.40 0.50 52 6.00% 5.2 5.2 4.5 132 2.46% 2.35 0.9 N/A N/A N/A 6.1 6.1 5.4
10 TOTAL BASIN C No 0.50 0.50 0.63 52 6.00% 4.4 4.4 3.5 132 2.46% 2.35 0.9 N/A N/A N/A 5.4 5.4 5.0
11 D1 No 0.85 0.85 1.00 42 2.64% 2.2 2.2 0.9 N/A N/A N/A 639 2.04% 2.86 3.7 5.9 5.9 5.0
11 D2 No 0.67 0.67 0.84 N/A N/A N/A N/A N/A N/A N/A 368 2.42% 3.11 2.0 5.0 5.0 5.0
12 D3 No 0.72 0.72 0.90 78 3.21% 4.3 4.3 2.3 217 1.43% 1.79 2.0 N/A N/A N/A 6.3 6.3 5.0
13 D4 No 0.59 0.59 0.73 18 2.94% 2.8 2.8 2.0 N/A N/A N/A 266 0.94% 1.94 2.3 5.1 5.1 5.0
14 D5 No 0.36 0.36 0.45 57 6.11% 5.7 5.7 5.1 487 1.71% 1.96 4.1 N/A N/A N/A 9.9 9.9 9.2
14 TOTAL BASIN D No 0.60 0.60 0.74 42 2.64% 4.4 4.4 3.1 247 1.23% 1.66 2.5 639 2.04% 2.86 3.7 10.6 10.6 9.3
15 UD1 No 0.85 0.85 1.00 165 3.33% 4.0 4.0 1.6 N/A N/A N/A N/A N/A N/A 5.0 5.0 5.0
16 UD2 No 0.26 0.26 0.33 87 11.64% 6.5 6.5 6.0 681 0.94% 1.46 7.8 N/A N/A N/A 14.2 14.2 13.7
17 OS1 Yes 0.32 0.32 0.40 1103 2.40% 36.2 36.2 32.5 2.00% N/A N/A N/A N/A N/A 36.2 36.2 32.5
18 OS2 No 0.32 0.32 0.40 20 2.00% 5.2 5.2 4.6 2420 2.10% 2.17 18.6 N/A N/A N/A 23.7 23.7 23.2
* Time of Concentrations are calculated for the entire basin and used for both the Impervious and Pervious portions of the basins.
PROPOSED TIME OF CONCENTRATION COMPUTATIONS
S. Thomas
Design
Point
Sub-Basin
Overland Flow SwaleConcentration Flow Gutter/Pipe Flow Time of
February 13, 2017
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
-
=
2/13/2017 7:09 AM D:\Projects\911-007\Drainage\Hydrology\911-007_Proposed_Rational_Calcs.xlsx\Tc
A1 1.74 0.42 0.28 0.55 0.24 Clayey | Average 2% to 7% 0.262 0.64 0.64 0.80 63%
A2 2.24 0.24 0.55 0.00 0.82 Clayey | Average 2% to 7% 0.627 0.75 0.75 0.94 66%
A3 1.46 0.00 0.08 0.00 0.21 Clayey | Average 2% to 7% 1.168 0.39 0.39 0.49 18%
TOTAL BASIN A 5.44 0.66 0.91 0.55 1.26 Clayey | Average 2% to 7% 2.058 0.62 0.62 0.77 52%
B1 0.47 0.36 0.02 0.00 0.00 Clayey | Average 2% to 7% 0.082 0.83 0.83 1.00 82%
B2 0.57 0.00 0.06 0.00 0.19 Clayey | Average 2% to 7% 0.314 0.57 0.57 0.71 41%
B3 1.27 0.29 0.34 0.00 0.44 Clayey | Average 2% to 7% 0.203 0.84 0.84 1.00 78%
B4 0.23 0.09 0.04 0.06 0.00 Clayey | Average 2% to 7% 0.040 0.65 0.65 0.81 64%
B5 1.31 0.00 0.01 0.68 0.00 Clayey | Average 2% to 7% 0.621 0.28 0.28 0.35 21%
TOTAL BASIN B 3.84 0.74 0.47 0.74 0.63 Clayey | Average 2% to 7% 1.259 0.60 0.60 0.74 53%
C1 0.36 0.00 0.08 0.00 0.12 Clayey | Average 2% to 7% 0.157 0.65 0.65 0.81 51%
C2 0.48 0.00 0.05 0.00 0.05 Clayey | Average 2% to 7% 0.382 0.40 0.40 0.50 19%
TOTAL BASIN C 0.85 0.00 0.13 0.00 0.18 Clayey | Average 2% to 7% 0.538 0.50 0.50 0.63 33%
D1 0.33 0.26 0.02 0.00 0.00 Clayey | Average 2% to 7% 0.046 0.85 0.85 1.00 85%
D2 1.71 0.47 0.32 0.23 0.23 Clayey | Average 2% to 7% 0.460 0.67 0.67 0.84 62%
D3 0.98 0.35 0.15 0.00 0.16 Clayey | Average 2% to 7% 0.327 0.72 0.72 0.90 64%
D4 0.66 0.12 0.11 0.30 0.07 Clayey | Average 2% to 7% 0.065 0.59 0.59 0.73 60%
D5 1.38 0.00 0.05 0.27 0.14 Clayey | Average 2% to 7% 0.914 0.36 0.36 0.45 20%
TOTAL BASIN D 5.05 1.20 0.64 0.80 0.60 Clayey | Average 2% to 7% 1.812 0.60 0.60 0.74 52%
UD1 0.05 0.03 0.02 0.00 0.00 Clayey | Average 2% to 7% 0.007 0.85 0.85 1.00 83%
UD2 4.07 0.00 0.07 0.00 0.00 Clayey | Average 2% to 7% 4.010 0.26 0.26 0.33 1%
TOTAL SITE 19.31 2.63 2.23 2.09 2.67 Clayey | Average 2% to 7% 9.684 0.53 0.53 0.66 41%
OS1 17.23 1.72 0.00 0.00 0.00 Clayey | Average 2% to 7% 15.506 0.32 0.32 0.40 10%
OS2 14.72 1.47 0.00 0.00 0.00 Clayey | Average 2% to 7% 13.248 0.32 0.32 0.40 10%
Composite Runoff Coefficient with Adjustment
PROPOSED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
2/13/2017 7:08 AM D:\Projects\911-007\Drainage\Hydrology\911-007_Proposed_Rational_Calcs.xlsx\Composite C
3 HB3 Yes 0.25 0.25 0.31 541 0.98% 37.2 37.2 34.5 0 N/A N/A N/A 37.2 37.2 34.5
EXISTING TIME OF CONCENTRATION COMPUTATIONS
S. Thomas
December 20, 2016
Design
Point
Sub-Basin
Overland Flow Swale Flow Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
-
=
12/20/2016 3:48 PM D:\Projects\911-007\Drainage\Hydrology\911-007_Existing_Rational_Calcs.xlsx\Tc
HA2 4.18 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 4.178 0.25 0.25 0.31 0%
HA3 0.33 0.15 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.178 0.57 0.57 0.71 45%
HB1 5.60 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 5.602 0.25 0.25 0.31 0%
HB2 0.47 0.21 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.254 0.57 0.57 0.71 45%
HB3 4.66 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 4.661 0.25 0.25 0.31 0%
1. Table RO-11 | Rational Method Runoff Coefficients for Composite Analysis
Composite Runoff Coefficient with Adjustment
EXISTING COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
12/20/2016 3:47 PM D:\Projects\911-007\Drainage\Hydrology\911-007_Existing_Rational_Calcs.xlsx\Composite C
elevations (MOEs) will need to be set at least 1 ft above the 100-yr WSEL with final
design. Water Quality is proposed within the pond volume through an approved outlet
structure. Additionally, Pond 2 will be designed to pass off-site flow safely through
the pond undetained.