HomeMy WebLinkAboutST. ELIZABETH ANN SETON CATHOLIC CHURCH EXPANSION - MAJOR AMENDMENT - MJA170001 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTCOLORADO CIVIL GROUP, INC.
DRAINAGE AND EROSION CONTROL
REPORT
FOR THE
ST. ELIZABETH ANN SETON
CATHOLIC CHURCH EXPANSION
CITY OF FORT COLLINS
SEPTEMBER 13, 2017
COLORADO CIVIL GROUP, INC. 5110 Granite St, Unit D Loveland, Colorado 80538 970-278-0029
September 13, 2017
Ms. Heather McDowell, PE
Water Utilities Engineering
City of Fort Collins
281 N College Avenue
Fort Collins, CO 80524
Re: St. Elizabeth Ann Seton Catholic Church Expansion
Project No. 0031.0012.00
Dear Ms. McDowell,
We are pleased to re-submit this Final Drainage and Erosion Control Report for the St.
Elizabeth Ann Seton Catholic Church Expansion project. This report was prepared based on
current City of Fort Collins and UDFCD storm drainage criteria.
Please let me know if you have any questions or comments.
Sincerely,
COLORADO CIVIL GROUP, INC.
David A. Huwa, PE
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
i
Table of Contents
1 Project Summary ...................................................................................................................................................... 1
1.1 Site Location ..................................................................................................................................................... 1
1.2 Project Description ........................................................................................................................................... 2
2 Project Imperviousness ............................................................................................................................................ 2
3 Proposed Drainage Facility Design ........................................................................................................................... 3
3.1 Four‐Step Process ............................................................................................................................................. 3
3.1.1 Step 1: Runoff Reduction .......................................................................................................................... 3
3.1.2 Step 2: Treat and Slowly Release Runoff .................................................................................................. 4
3.1.3 Step 3: Stabilize Drainageways ................................................................................................................. 5
3.1.4 Step 4: Implementation of Source Controls ............................................................................................. 6
3.2 BMP Selection Considerations .......................................................................................................................... 6
3.2.1 Soils ........................................................................................................................................................... 6
3.2.2 Watershed Size ......................................................................................................................................... 6
3.2.3 Base Flows ................................................................................................................................................ 7
3.3 BMP Design ....................................................................................................................................................... 7
3.3.1 Grass Swale ............................................................................................................................................... 7
3.3.2 Rain Garden .............................................................................................................................................. 7
4 Hydrologic Analysis ................................................................................................................................................... 8
5 Stormwater Detention Analysis................................................................................................................................ 8
6 Existing Swale Capacity ........................................................................................................................................... 10
7 Conclusions ............................................................................................................................................................. 10
Appendix A: Previous Reports .......................................................................................................................................... A
Appendix B: Existing Soil Properties ................................................................................................................................. B
Appendix C: BMP Sizing and Detention Calculations ...................................................................................................... C
Appendix D: Grading and Erosion Control Plan, Drainage Plan ....................................................................................... D
Index of Figures and Tables
Figure 1‐1: Vicinity Map ................................................................................................................................................... 1
Table 2‐1: UDFCD Percent Impervious Recommendations .............................................................................................. 2
Table 2‐2: New & Future Improvements Imperviousness ............................................................................................... 3
Table 3‐1: LID Treatment .................................................................................................................................................. 8
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
1
1 Project Summary
1.1 Site Location
The St. Elizabeth Ann Seton (SEAS) site, approximately 11.7 acres, is located in the
Southwest Quarter of Section 6, Township 7 North, Range 68 West of the 6th Principal
Meridian, City of Fort Collins, County of Larimer, Colorado. The site is bounded on
the north by Seton Street and on the west by South Lemay Avenue, on the South by
Southridge Greens Blvd., and on the east by Southridge Golf Course. A vicinity map
is presented in Figure 1-1 below. The project area is generally located at Latitude 40°
30’35.82” and Longitude -105° 03’23.96”. The site is part of the Fossil Creek
Drainage Basin and is included as part of the Fossil Creek Drainage Basin Master
Drainageway Planning Restudy Phase A.
Figure 1-1: Vicinity Map
ST. ELIZABETH
ANN SETON
S LEMAY AVE
S COLLGE AVE
SOUTHRIDGE GREENS
BLVD.
FOSSILL
CREEK PKWY
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
2
1.2 Project Description
The SEAS site consists of the existing St. Elizabeth Ann Seton Church, existing
parking lots, outdoor sheds, and an existing stormwater drainage system. The existing
drainage system includes a detention pond at the southwest corner of the property.
The project site is located within Community-Panel Number 08069C1000F. A note on
the panel indicates that “No Special Flood Hazard Areas” are present, and so panel is
not printed. The FEMA Map Index showing this is found in Appendix B of this report.
The proposed improvements include a new worship area, additional concrete walkways,
and a concrete paved access for emergency fire equipment. Several storm drainage
improvements will also be required due to the additional impervious area. Additionally,
this report includes an evaluation of a future impervious improvement, likely an onsite
residence for the Church’s Father and additional parking, and will be located in
undeveloped areas of the site. The future impervious area will be included in the LID
and detention requirements discussed in this report.
2 Project Imperviousness
In order to determine the type of stormwater detention and treatment necessary for the
project site, the area of the planned improvements was totaled to determine new impervious
area. The Urban Drainage and Flood Control District (UDFCD) recommendations for percent
impervious were used to determine the overall imperviousness and are presented in Table 2-
1.
Table 2-1: UDFCD Percent Impervious Recommendations
Land Use of Surface
Characteristics
Percentage
Imperviousness
Paved Streets 100%
Drives and Walks 90%
Roofs 90%
Landscaped Areas 2%
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
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The new and future improvements areas and imperviousness are presented in Table 2-2
below.
Table 2-2: New & Future Improvements Imperviousness
Area Identification
Basin Categories and Areas (SF)
Percent
Streets Impervious
Drives, Walks,
& Roofs
100% 90%
Concrete Emergency Access 6,800 0 100%
Concrete Walkways 0 4,000 90%
Church Addition 0 11,000 90%
Future Parking 9,500 0 100%
Future Residence 0 5,000 90%
TOTAL 16,300 20,000 94%
This imperviousness has been used to evaluate the existing detention pond, and additional
detention required. Additionally, this imperviousness has been used to determine the LID
requirements for the project.
3 Proposed Drainage Facility Design
This section of the report presents the design of drainage facilities required based on the
addition of new and future impervious area as detailed above. The drainage design has
been explained as it pertains to the “Four-Step Process for Stormwater Quality Management”
as outlined by UDFCD and adopted by the City of Fort Collins.
3.1 Four‐Step Process
3.1.1 Step 1: Runoff Reduction
The first step in stormwater quality management is to reduce runoff peaks,
volumes, and pollutant loads from urbanizing areas by implementing Low Impact
Development (LID) strategies. LID practices include reducing unnecessary
impervious areas and routing runoff from impervious surfaces over permeable
areas to slow runoff and promote infiltration.
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
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The SEAS project does include an increase in impervious area with the
construction of the proposed improvements detailed above. Runoff generated
from the new impervious areas is discharged onto a vegetated buffer prior to
entering the existing detention pond, which will promote filtering of the runoff
and some infiltration which helps to reduce the peak discharge. The buffer
width varies from roughly 50 feet to more than 100 feet.
3.1.2 Step 2: Treat and Slowly Release Runoff
After reducing the runoff from a site, the second step in stormwater quality
management is to capture and slowly release a Water Quality Capture Volume
(WQCV). WQCV facilities may include bioretention, extended detention basins,
sand filters, constructed wetland ponds, and retention ponds.
The existing detention pond was designed with a WQCV and outlet. These
facilities are not expected to be altered with the proposed improvements for the
SEAS project. To address the additional impervious areas, and City of Fort
Collins drainage requirements, a Rain Garden has been designed and will be
constructed to capture a portion of the sites runoff prior to entering the
detention pond. Since the proposed improvements span a wide area, it is
difficult to capture all of the discharged runoff efficiently, so an ‘area-swap’ is
being proposed. The new and future impervious areas total 36,300 square-feet.
The existing southeast parking lot (Sub-Basin 35) totals 1.3 acres, and has an
imperviousness of 84.7%. A second area, a portion of Sub-Basin 30, also drains
to the new rain garden. Sub-Basin 30 totals 3.4 acres, but the estimate
contributing area is 2.27 acres, and has an imperviousness of 41.2%. A rain
garden has been designed to treat runoff generated from those portions of Sub-
Basins 30 and 35 that flow to the rain garden, which far exceeds the additional
impervious area from the new improvements. The exhibit on the following page
shows new and future impervious areas in green shading. The tributary
portions of Sub-Basins 30 and 35, existing grass swale, and proposed rain
garden are shown in orange shading. The rain garden will allow for infiltration
and reduce the peak discharge from impervious areas of the site.
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
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3.1.3 Step 3: Stabilize Drainageways
Although steps 1 and 2 help to minimize the effects of runoff on downstream
drainageways, natural drainageways are often subject to bed and bank erosion
due to increases in the frequency, rate, duration, and volume of runoff. Step 3
includes measures to prevent drainageway erosion.
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
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There are no proposed drainageways planned for the SEAS site. By
implementing steps 1 and 2, the project site does its part to reduce
drainageway erosion downstream. Additionally, all disturbed areas will either be
paved, re-seeded or landscaped in order to achieve stabilization. And all runoff
from the site enters the existing detention pond, so off-site downstream
drainageways should be adequately protected.
3.1.4 Step 4: Implementation of Source Controls
The final step in stormwater quality management is source control. Site specific
needs such as material storage or other site operations require consideration of
targeted source control Best Management Practices (BMPs). These BMPs are
shown on the Grading & Erosion Control Plan, found in Appendix D of this
report. Expected source erosion control BMP’s include straw wattles, inlet and
outlet protection, and re-seeding.
3.2 BMP Selection Considerations
The following sections discuss the considerations for determining the best BMP or LID
solution to implement for the project.
3.2.1 Soils
The existing soil condition on the project site must be considered when
designing BMPs. Soils with good permeability provide opportunities for
infiltration of runoff and are well-suited for infiltration-based BMPs such as rain
gardens, permeable pavement, and grass swales. The soil on the SEAS site
are in Hydrologic Soil Group B and C, which is defined as soils having a
moderate to slow infiltration when thoroughly wet. Roughly 75% of the soils are
Group B, and for this reason, infiltration based BMPs were considered a good
option for the project site. Soil information for the site may be found in
Appendix B.
3.2.2 Watershed Size
The contributing drainage area is an important consideration for the design of
BMPs. The SEAS site is approximately 11.7 acres. An existing detention pond
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
7
and WQCV facility will continue to be utilized with the new improvements. A
rain garden is proposed to filter runoff from a portion of the site prior to
entering the existing detention pond.
3.2.3 Base Flows
BMPs such as constructed wetlands ponds, retention ponds, and wetland
channels require a base flow to prevent the BMPs from becoming dry and
unable to support wetland vegetation. No base flow exists for the SEAS project
site, so no BMPs that require a base flow were considered for the site.
3.3 BMP Design
3.3.1 Grass Swale
Grass swales are vegetated channels with low longitudinal slopes and broad
cross-sections that convey flow in a slow and shallow manner to facilitate
sedimentation.
For the SEAS project, much of the sites runoff is conveyed to small, shallow
grass swales located along the west and south boundaries of the site and
discharge runoff into the existing detention pond. These existing grass swales
will continue to collect and convey runoff to the existing detention pond.
3.3.2 Rain Garden
A rain garden utilizes bioretention to reduce the transportation of pollutants to
downstream receiving waters through sedimentation, filtering, adsorption,
evapotranspiration, and biological uptake of constituents. The UDFCD provides
guidelines and tools for the design of rain gardens, which have been used for
the SEAS project. The sizing calculations` have been included in Appendix C.
The City of Fort Collins LID ordinance requires that for 75% of all newly added
or modified impervious areas be treated by LID techniques. Table 3-1 shows
how the LID requirements have been met for this project. The table shows that
a larger area is treated than is required by Ft. Collins ordinance, which is due
to the configuration of the new and future improvements. An area of
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
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approximately 155,509 sf is tributary to the proposed rain garden, and at 57%
imperviousness, approximately 88,640 sf of impervious surface will be treated.
Table 3-1: LID Treatment
75% MIN. ON‐SITE TREATMENT BY LID FOR NEW & FUTURE IMPROVEMENTS
PROJECT AREA
NEW & FUTURE IMPERVIOUS AREAS 36,300 SF
REQUIRED MINIMUM AREA TO BE TREATED BY LID (75% OF
NEW COMMERCIAL IMPERVIOUS AREA) 27,225 SF
TRIBUTARY PORTIONS OF EXISTING SUB‐BASINS 30 AND 35 155,509 SF
4 Hydrologic Analysis
The location and configuration of new improvements causes surface runoff to drain directly to
the existing detention pond, and the runoff is not intercepted by existing drainage
infrastructure like inlets and storm sewers. Because of this, a hydrologic analysis of the site
has not been performed. If a hydrologic analysis were to be performed, per City of Fort
Collins criteria, the Rational Formula Method would be used. The rainfall intensities from the
Fort Collins Amendments to the UDFCD manual Table RA-7 were used for the calculation of
runoff for a 100-year storm event.
5 Stormwater Detention Analysis
The earliest Drainage and Erosion Control Report for the SEAS site found, was prepared by
Ayers Associates, Inc., and dated November 2, 1998. Within this report, the 11.7 acre
SEAS site was described with an existing detention pond having a 100-year volume of 0.907
acre-foot at an elevation of 4934.55. The detention pond had a release rate of 12.27 cfs
with 2.65 feet of freeboard. The vertical datum used in this drainage report was NGVD
1929, while the current site survey is the NAVD 1988 datum. A vertical datum shift has
been performed using the VERTCON website, and shows that the NAVD 1988 datum is
3.01 feet higher than the NGVD 1929 datum.
A later site improvement at SEAS required a new Drainage and Erosion Control Report.
This report was prepared by Ayers Associates, Inc., and dated June 30, 2003. Within this
report, the 11.7 acre SEAS site was again described with an existing detention pond and
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
9
was modified to include a WQCV outlet structure. The detention pond was modified to
detain 1.79 acre-feet at a depth of 5.66 feet, and release runoff at a rate of 12.0 cfs. The
100-year water surface elevation was 4936.41, and the pond had 1.0 feet of freeboard. The
vertical datum again used in this drainage report was the NGVD 1929 datum. The 100-year
water surface elevation is 4939.42 using the NAVD 1988 datum. Pertinent portions of these
reports are found in Appendix A.
Detention Pond Release Rate
The SEAS site is located within the Fossil Creek Drainage Basin, a basin that was
evaluated in 2004 and determined should have reduced release rates for developed
properties. After conversations with the City of Fort Collins Utilities Department, it was
determined that the SEAS site will be grand-fathered with regard to release rates, and the
existing release rate of 12.0 cfs can be used as the release rate moving forward with new
and future improvements. An email from the Utilities Department describing this decision is
provided in Appendix C. An orifice calculation was performed for the existing 12-inch outlet
pipe. UDFCD Equation 12-19 was used to estimate the discharge capacity of the existing
12-inch outlet pipe. The expected discharge is 8.6 cfs with a ponding depth of 5.66 feet
from the 2003 drainage report, and assumes no tailwater influence. This is significantly less
than previous drainage reports have indicated, which was 12 cfs.
Detention Pond with New & Future Improvements
A UDFCD Modified FAA evaluation was performed to determine the required detention
volume for the new and future improvements. The 100-year required volume was
determined assuming a release rate of 1.02 cfs/acre (12 cfs / 11.7 acres). The required
volume (0.14 acre-feet) was added to the existing volume (1.79 acre-feet) described in the
previous drainage reports, and a new ponding depth was determined. The existing ponding
depth was described as 5.66 feet, and the new ponding depth considering the new and
future improvements is 5.89 feet, resulting in a new 100-year water surface elevation of
4939.65. The UDFCD orifice equation was used with a new ponding depth of 5.89 feet.
The result shows a discharge of 8.78 cfs, which is still less than the 12 cfs that has been
approved by the City of Fort Collins Utilities Department. The freeboard of the existing
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
10
detention pond will be reduced from 1.0 feet to 0.77 feet, which is considered an acceptable
reduction, and does not require raising of the perimeter berm of the detention pond. The
calculations are found in Appendix C.
6 Existing Swale Capacity
There is an existing grass swale located south of the existing church and proposed addition
that collects tributary runoff from Sub-Basins 30 and 35. The original 1998 SWMM analysis
showed a 100-year proposed discharge from Sub-basin 30 of 15.9 cfs, and 7.3 cfs for Sub-
Basin 35. The 1998 analysis was performed using older hydrology criteria prior to the
Spring Creek Flood. When the site was improved several years later, the 2003 SWMM
analysis showed the 100-year proposed discharge from Sub-Basin 30 as 30.1 cfs. The 100-
year proposed discharge from Sub-Basin 35 is 12.6 cfs. The two sub-basins added together
(4.7 acres) total 42.7 cfs, no attenuation is considered in this flow rate. The slope of the
existing swale is approximately 7%, with 15:1 side slopes. The depth of the existing swale
ranges from 0.6 feet to 0.8 feet. Using the UDFCD spreadsheet for a normal depth analysis
of the swale, shows a range in capacity of 27.2 cfs to 58.6 cfs based on flow depth. As
previously mentioned, the totaled flow from the two sub-basins is 42.7 cfs, but has not been
attenuated. Additionally, a portion of Sub-Basin 30 does not drain to the swale, and so the
flow should be reduced. Based on this information, it is believed the existing swale is
reasonably sized based on pervious drainage designs. The normal depth calculations are
found in Appendix C.
7 Conclusions
The final drainage design for the St. Elizabeth Ann Seton Catholic Church Expansion project,
as outlined in this Final Drainage and Erosion Control Report, meets or exceeds the
drainage criteria set forth by the City of Fort Collins and the UDFCD. The design safely
and effectively collects and conveys runoff per the applicable criteria and mimics existing
drainage patterns where possible. The Final Drainage Plan map is found in Appendix D.
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
A
Appendix A: Previous Reports
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
This unofficial copy was downloaded on May-28-2015 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
B
Appendix B: Existing Soil Properties
Drainage Class—Larimer County Area, Colorado
(DRAINAGE CLASS)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 1 of 3
4484250 4484290 4484330 4484370 4484410 4484450 4484490
4484250 4484290 4484330 4484370 4484410 4484450 4484490
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
40° 30' 40'' N
105° 3' 31'' W
40° 30' 40'' N
105° 3' 15'' W
40° 30' 32'' N
105° 3' 31'' W
40° 30' 32'' N
105° 3' 15'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:1,700 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
Excessively drained
Somewhat excessively
drained
Well drained
Moderately well drained
Somewhat poorly drained
Poorly drained
Very poorly drained
Subaqueous
Not rated or not available
Soil Rating Lines
Excessively drained
Somewhat excessively
drained
Well drained
Moderately well drained
Somewhat poorly drained
Poorly drained
Very poorly drained
Subaqueous
Not rated or not available
Soil Rating Points
Excessively drained
Somewhat excessively
drained
Well drained
Moderately well drained
Somewhat poorly drained
Poorly drained
Very poorly drained
Subaqueous
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:
Coordinate System: Web Mercator (EPSG:3857)
Drainage Class
Drainage Class— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
27 Cushman fine sandy
loam, 3 to 9 percent
slopes
Well drained 3.1 26.6%
35 Fort Collins loam, 0 to 3
percent slopes
Well drained 0.3 2.1%
55 Kim loam, 5 to 9 percent
slopes
Well drained 0.4 3.4%
103 Stoneham loam, 5 to 9
percent slopes
Well drained 6.1 52.3%
119 Wiley silt loam, 3 to 5
percent slopes
Well drained 1.8 15.6%
Totals for Area of Interest 11.7 100.0%
Description
"Drainage class (natural)" refers to the frequency and duration of wet periods
under conditions similar to those under which the soil formed. Alterations of the
water regime by human activities, either through drainage or irrigation, are not a
consideration unless they have significantly changed the morphology of the soil.
Seven classes of natural soil drainage are recognized-excessively drained,
somewhat excessively drained, well drained, moderately well drained, somewhat
poorly drained, poorly drained, and very poorly drained. These classes are
defined in the "Soil Survey Manual."
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Drainage Class—Larimer County Area, Colorado DRAINAGE CLASS
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 3 of 3
Hydrologic Soil Group—Larimer County Area, Colorado
(HYDROLOGIC SOIL GROUP)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 1 of 4
4484250 4484290 4484330 4484370 4484410 4484450 4484490
4484250 4484290 4484330 4484370 4484410 4484450 4484490
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
40° 30' 40'' N
105° 3' 31'' W
40° 30' 40'' N
105° 3' 15'' W
40° 30' 32'' N
105° 3' 31'' W
40° 30' 32'' N
105° 3' 15'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:1,700 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil 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:
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
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
27 Cushman fine sandy
loam, 3 to 9 percent
slopes
C 3.1 26.6%
35 Fort Collins loam, 0 to 3
percent slopes
C 0.3 2.1%
55 Kim loam, 5 to 9 percent
slopes
B 0.4 3.4%
103 Stoneham loam, 5 to 9
percent slopes
B 6.1 52.3%
119 Wiley silt loam, 3 to 5
percent slopes
B 1.8 15.6%
Totals for Area of Interest 11.7 100.0%
Hydrologic Soil Group—Larimer County Area, Colorado HYDROLOGIC SOIL GROUP
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 3 of 4
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
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Larimer County Area, Colorado HYDROLOGIC SOIL GROUP
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 4 of 4
Wind Erodibility Group—Larimer County Area, Colorado
(WIND ERODIBILITY GROUP)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 1 of 3
4484250 4484290 4484330 4484370 4484410 4484450 4484490
4484250 4484290 4484330 4484370 4484410 4484450 4484490
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
40° 30' 40'' N
105° 3' 31'' W
40° 30' 40'' N
105° 3' 15'' W
40° 30' 32'' N
105° 3' 31'' W
40° 30' 32'' N
105° 3' 15'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:1,700 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Lines
1
2
3
4
4L
5
6
7
8
Not rated or not available
Soil Rating Points
1
2
3
4
4L
5
6
7
8
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:
Coordinate System: Web Mercator (EPSG:3857)
Wind Erodibility Group
Wind Erodibility Group— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
27 Cushman fine sandy
loam, 3 to 9 percent
slopes
3 3.1 26.6%
35 Fort Collins loam, 0 to 3
percent slopes
5 0.3 2.1%
55 Kim loam, 5 to 9 percent
slopes
4L 0.4 3.4%
103 Stoneham loam, 5 to 9
percent slopes
6 6.1 52.3%
119 Wiley silt loam, 3 to 5
percent slopes
4L 1.8 15.6%
Totals for Area of Interest 11.7 100.0%
Description
A wind erodibility group (WEG) consists of soils that have similar properties
affecting their susceptibility to wind erosion in cultivated areas. The soils
assigned to group 1 are the most susceptible to wind erosion, and those
assigned to group 8 are the least susceptible.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Lower
Wind Erodibility Group—Larimer County Area, Colorado WIND ERODIBILITY GROUP
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 3 of 3
Wind Erodibility Index—Larimer County Area, Colorado
(WIND ERODIBILITY INDEX)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 1 of 3
4484250 4484290 4484330 4484370 4484410 4484450 4484490
4484250 4484290 4484330 4484370 4484410 4484450 4484490
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
495030 495070 495110 495150 495190 495230 495270 495310 495350 495390
40° 30' 40'' N
105° 3' 31'' W
40° 30' 40'' N
105° 3' 15'' W
40° 30' 32'' N
105° 3' 31'' W
40° 30' 32'' N
105° 3' 15'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:1,700 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Lines
0
38
48
56
86
134
160
180
220
250
310
Not rated or not available
Soil Rating Points
0
38
48
56
86
134
160
180
220
250
310
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
Wind Erodibility Index
Wind Erodibility Index— Summary by Map Unit — Larimer County Area, Colorado (CO644)
Map unit symbol Map unit name Rating (tons per acre
per year)
Acres in AOI Percent of AOI
27 Cushman fine sandy
loam, 3 to 9 percent
slopes
86 3.1 26.6%
35 Fort Collins loam, 0 to 3
percent slopes
56 0.3 2.1%
55 Kim loam, 5 to 9 percent
slopes
86 0.4 3.4%
103 Stoneham loam, 5 to 9
percent slopes
48 6.1 52.3%
119 Wiley silt loam, 3 to 5
percent slopes
86 1.8 15.6%
Totals for Area of Interest 11.7 100.0%
Description
The wind erodibility index is a numerical value indicating the susceptibility of soil
to wind erosion, or the tons per acre per year that can be expected to be lost to
wind erosion. There is a close correlation between wind erosion and the texture
of the surface layer, the size and durability of surface clods, rock fragments,
organic matter, and a calcareous reaction. Soil moisture and frozen soil layers
also influence wind erosion.
Rating Options
Units of Measure: tons per acre per year
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Wind Erodibility Index—Larimer County Area, Colorado WIND ERODIBILITY INDEX
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 3 of 3
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
C
Appendix C: BMP Sizing
and Detention Calculations
1
David Huwa
From: Heather McDowell <hmcdowell@fcgov.com>
Sent: Friday, June 23, 2017 2:07 PM
To: David Huwa
Subject: RE: St. Elizabeth Ann Seton - OLDER DRAINAGE REPORTS
Hi David, I talked with others in our group about this one and basically you are grandfathered in the existing release rate
from the site (I believe this is the 12.4 cfs or the 13.6 cfs release rate discussed in the 2003 drainage report) but should
not be increasing this release rate with the new improvements to your site. Let me know if you want to discuss this any
further. Thanks!
Heather McDowell, P.E.
Water Utilities Engineering
City of Fort Collins
Office 970.224.6065
Mobile 970.218.9225
hmcdowell@fcgov.com
From: David Huwa [mailto:dhuwa@ccginc.us]
Sent: Wednesday, June 21, 2017 1:55 PM
To: Heather McDowell
Cc: David Huwa
Subject: St. Elizabeth Ann Seton - OLDER DRAINAGE REPORTS
Heather,
I’ve provided a DropBox link below so you can download the older drainage reports. Let me know what you
think. Thanks.
https://www.dropbox.com/sh/n42pl27n81gn45b/AABU8GPNLiGi9ztnwonjtFgka?dl=0
David A. Huwa, P.E.
CCG
Colorado Civil Group, Inc.
5110 Granite St., Unit D
Loveland, CO 80538
www.ccginc.us
p: 970.278.0029
c: 970.290.4325
dhuwa@ccginc.us
DRAWING DISCLAIMER
Colorado Civil Group, Inc. (CCG) transmits this electronic file(s) for reference only. The enclosed file(s) shall not be modified, altered, copied, distributed to third parties, or used
on any
2
other project, without prior written permission from CCG. These file(s) are not to be used, in whole or in part, as Construction Documents or Shop Drawings, without CCGs’ official seal
and signature on each document. Any use of the enclosed file(s) other than that herewith expressed, will be prosecuted to the fullest extent permitted by law.
Project:
Basin ID:
Design Information (Input): Design Information (Input):
Catchment Drainage Imperviousness Ia = 94.00 percent Catchment Drainage Imperviousness I
a = 94.00 percent
Catchment Drainage Area A = 0.827 acres Catchment Drainage Area A = 0.827 acres
Predevelopment NRCS Soil Group Type = B A, B, C, or D Predevelopment NRCS Soil Group Type = B A, B, C, or D
Return Period for Detention Control T = 2 years (2, 5, 10, 25, 50, or 100) Return Period for Detention Control T = 100 years (2, 5, 10, 25, 50, or 100)
Time of Concentration of Watershed Tc = 5 minutes Time of Concentration of Watershed Tc = 5 minutes
Allowable Unit Release Rate q = 0.15 cfs/acre Allowable Unit Release Rate q = 1.02 cfs/acre
One-hour Precipitation P1 = 0.82 inches One-hour Precipitation P
1 = 2.86 inches
Design Rainfall IDF Formula i = C1* P1
/(C2+Tc
)^C3 Design Rainfall IDF Formula i = C1
* P1/(C2
+Tc)^C3
Coefficient One C1 = 28.50 Coefficient One C
1 = 28.50
Coefficient Two C2 = 9 Coefficient Two C
2 =9
Coefficient Three C3 = 0.789 Coefficient Three C
3 = 0.789
Determination of Average Outflow from the Basin (Calculated): Determination of Average Outflow from the Basin (Calculated):
Runoff Coefficient C = 0.77 Runoff Coefficient C = 0.86
Inflow Peak Runoff Qp-in = 1.86 cfs Inflow Peak Runoff Qp-in = 7.23 cfs
Allowable Peak Outflow Rate Qp-out = 0.13 cfs Allowable Peak Outflow Rate Qp-out = 0.84 cfs
Mod. FAA Minor Storage Volume = 1,865 cubic feet Mod. FAA Major Storage Volume = 5,935 cubic feet
Mod. FAA Minor Storage Volume = 0.043 acre-ft Mod. FAA Major Storage Volume = 0.136 acre-ft
5 <- Enter Rainfall Duration Incremental Increase Value Here (e.g. 5 for 5-Minutes)
Rainfall Rainfall Inflow Adjustment Average Outflow Storage Rainfall Rainfall Inflow Adjustment Average Outflow Storage
Duration Intensity Volume Factor Outflow Volume Volume Duration Intensity Volume Factor Outflow Volume Volume
minutes inches / hr acre-feet "m" cfs acre-feet acre-feet minutes inches / hr acre-feet "m" cfs acre-feet acre-feet
(input) (output) (output) (output) (output) (output) (output) (input) (output) (output) (output) (output) (output) (output)
0 0.00 0.000 0.00 0.00 0.000 0.000 0 0.00 0.000 0.00 0.00 0.000 0.000
5 2.91 0.013 1.00 0.13 0.001 0.012 5 10.16 0.050 1.00 0.84 0.006 0.044
10 2.29 0.020 0.75 0.10 0.001 0.019 10 7.98 0.078 0.75 0.63 0.009 0.070
15 1.90 0.025 0.67 0.08 0.002 0.023 15 6.64 0.098 0.67 0.56 0.012 0.086
20 1.64 0.029 0.63 0.08 0.002 0.027 20 5.72 0.112 0.63 0.53 0.015 0.098
25 1.45 0.032 0.60 0.08 0.003 0.029 25 5.05 0.124 0.60 0.51 0.017 0.106
30 1.30 0.034 0.58 0.07 0.003 0.031 30 4.53 0.133 0.58 0.49 0.020 0.113
35 1.18 0.036 0.57 0.07 0.004 0.033 35 4.12 0.141 0.57 0.48 0.023 0.118
40 1.08 0.038 0.56 0.07 0.004 0.034 40 3.78 0.148 0.56 0.47 0.026 0.122
45 1.00 0.040 0.56 0.07 0.004 0.035 45 3.50 0.154 0.56 0.47 0.029 0.125
50 0.94 0.041 0.55 0.07 0.005 0.036 50 3.27 0.160 0.55 0.46 0.032 0.128
55 0.88 0.042 0.55 0.07 0.005 0.037 55 3.06 0.165 0.55 0.46 0.035 0.130
60 0.83 0.044 0.54 0.07 0.006 0.038 60 2.89 0.170 0.54 0.46 0.038 0.132
65 0.78 0.045 0.54 0.07 0.006 0.039 65 2.73 0.174 0.54 0.45 0.041 0.133
70 0.74 0.046 0.54 0.07 0.007 0.039 70 2.59 0.178 0.54 0.45 0.044 0.134
75 0.71 0.047 0.53 0.07 0.007 0.040 75 2.47 0.182 0.53 0.45 0.046 0.135
80 0.68 0.048 0.53 0.07 0.007 0.040 80 2.36 0.185 0.53 0.45 0.049 0.136
85 0.65 0.048 0.53 0.07 0.008 0.040 85 2.26 0.188 0.53 0.45 0.052 0.136
90 0.62 0.049 0.53 0.07 0.008 0.041 90 2.17 0.191 0.53 0.45 0.055 0.136
95 0.60 0.050 0.53 0.07 0.009 0.041 95 2.09 0.194 0.53 0.44 0.058 0.136
100 0.58 0.051 0.53 0.07 0.009 0.041 100 2.01 0.197 0.53 0.44 0.061 0.136
105 0.56 0.051 0.52 0.07 0.010 0.042 105 1.94 0.200 0.52 0.44 0.064 0.136
110 0.54 0.052 0.52 0.07 0.010 0.042 110 1.88 0.202 0.52 0.44 0.067 0.136
115 0.52 0.053 0.52 0.07 0.011 0.042 115 1.82 0.205 0.52 0.44 0.070 0.135
120 0.51 0.053 0.52 0.07 0.011 0.042 120 1.76 0.207 0.52 0.44 0.073 0.134
125 0.49 0.054 0.52 0.07 0.011 0.042 125 1.71 0.209 0.52 0.44 0.076 0.134
Project:
Basin ID:
DETENTION VOLUME BY THE MODIFIED FAA METHOD
ST. ELIZABETH ANN SETON
UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.34, Released November 2013
0
0.05
0.1
0.15
0.2
0.25
0.3
0 50 100 150 200 250 300 350
Volume (acre-feet)
Duration (Minutes)
Inflow and Outflow Volumes vs. Rainfall Duration
Minor Storm Inflow Volume Minor Storm Outflow Volume Minor Storm Storage Volume Major Storm Inflow Volume Major Storm Outflow Volume Major Storm Storage Volume
2017.09.13_DETENTION POND.xls, Modified FAA 9/12/2017, 5:27 PM
Project:
Basin ID:
Design Information (Input):
Width of Basin Bottom, W = ft Right Triangle OR…
Length of Basin Bottom, L = ft Isosceles Triangle OR…
Dam Side-slope (H:V), Zd = ft/ft Rectangle OR…
Circle / Ellipse OR…
Irregular (Use Overide values in cells G32:G52)
MINOR MAJOR
Storage Requirement from Sheet 'Modified FAA': 0.04 0.14 acre-ft.
Stage-Storage Relationship: Storage Requirement from Sheet 'Hydrograph': acre-ft.
Storage Requirement from Sheet 'Full-Spectrum': acre-ft.
Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes
for WQCV, Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WQCV, Minor,
& Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage & Major Storage
Stages ft ft/ft ft ft ft
2
ft
2
User ft
3
acres acre-ft Volumes
(input) (input) Below El. (output) (output) (output) Overide (output) (output) (output) (for goal seek)
4933.76 (input) 0 0.000 0.000
4934.00 0.00 0.00 19 2 0.000 0.000
4935.00 0.00 0.00 3,950 1,987 0.091 0.046
4936.00 0.00 0.00 12,274 10,099 0.282 0.232
4937.00 0.00 0.00 17,033 24,752 0.391 0.568
4938.00 0.00 0.00 21,029 43,783 0.483 1.005
4939.00 0.00 0.00 24,710 66,653 0.567 1.530
4940.00 0.00 0.00 28,918 93,467 0.664 2.146
4940.50 0.00 0.00 30,350 108,284 0.697 2.486
#N/A #N/A
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#N/A #N/A
Project:
Basin ID:
STAGE-STORAGE SIZING FOR DETENTION BASINS
0.00
1000.00
2000.00
3000.00
4000.00
5000.00
6000.00
0.00 0.50 1.00 1.50 2.00 2.50 3.00
Stage (ft. elev.)
Storage (acre-feet)
STAGE-STORAGE CURVE FOR THE POND
2017.09.13_DETENTION POND.xls, Basin 9/12/2017, 5:28 PM
Urban Drainage Orifice Equation (12‐19)
Existing Detention Pond
Q = CA(2gH)^0.5
Target Orifice Discharge 12 cfs
Actual Radius 6 inches
Water Depth 5.66 feet
C = 0.6
g = 32.2 ft/sec^2
H = 5.16 ft
A = 0.785398 ft^2
Q = 8.590312 cfs Good
Urban Drainage Orifice Equation (12‐19)
Existing Detention Pond with New & Future Improvements
Q = CA(2gH)^0.5
Target Orifice Discharge 12 cfs
Actual Radius 6 inches
Water Depth 5.89 feet
C = 0.6
g = 32.2 ft/sec^2
H = 5.39 ft
A = 0.785398 ft^2
Q = 8.779675 cfs Good
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 57.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.570
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.18 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 155,509 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.40 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 2,184.3 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 = 1773 sq ft
D) Actual Flat Surface Area AActual = 1785 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 2590 sq ft
F) Rain Garden Total Volume VT= 2,188 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 = ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = N/A cu ft
iii) Orifice Diameter, 3/8" Minimum DO = N/A in
Design Procedure Form: Rain Garden (RG)
DAH
COLORADO CIVIL GROUP, INC.
September 12, 2017
ST. ELIZABETH ANN SETON
FT. COLLINS
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
2017.09.13_LID CALCS - RAIN GARDEN.xlsm, RG 9/12/2017, 3:21 PM
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)
DAH
COLORADO CIVIL GROUP, INC.
September 12, 2017
ST. ELIZABETH ANN SETON
FT. COLLINS
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
2017.09.13_LID CALCS - RAIN GARDEN.xlsm, RG 9/12/2017, 3:21 PM
Project:
Channel ID:
Design Information (Input)
Channel Invert Slope So = 0.0700 ft/ft
Manning's n n = 0.035
Bottom Width B = 0.00 ft
Left Side Slope Z1 = 15.00 ft/ft
Right Side Slope Z2 = 15.00 ft/ft
Freeboard Height F = 0.00 ft
Design Water Depth Y = 0.60 ft
Normal Flow Condtion (Calculated)
Discharge Q = 27.22 cfs
Froude Number Fr = 1.62
Flow Velocity V = 5.04 fps
Flow Area A = 5.40 sq ft
Top Width T = 18.00 ft
Wetted Perimeter P = 18.04 ft
Hydraulic Radius R = 0.30 ft
Hydraulic Depth D = 0.30 ft
Specific Energy Es = 0.99 ft
Centroid of Flow Area Yo = 0.20 ft
Specific Force Fs = 0.33 kip
Normal Flow Analysis - Trapezoidal Channel
St. Elizabeth Ann Seton
Existing South Swale
2017.09.13_SEAS EX SOUTH SWALE.xls, Basics 9/12/2017, 3:01 PM
Project:
Channel ID:
Design Information (Input)
Channel Invert Slope So = 0.0700 ft/ft
Manning's n n = 0.035
Bottom Width B = 0.00 ft
Left Side Slope Z1 = 15.00 ft/ft
Right Side Slope Z2 = 15.00 ft/ft
Freeboard Height F = 0.00 ft
Design Water Depth Y = 0.80 ft
Normal Flow Condtion (Calculated)
Discharge Q = 58.61 cfs
Froude Number Fr = 1.70
Flow Velocity V = 6.11 fps
Flow Area A = 9.60 sq ft
Top Width T = 24.00 ft
Wetted Perimeter P = 24.05 ft
Hydraulic Radius R = 0.40 ft
Hydraulic Depth D = 0.40 ft
Specific Energy Es = 1.38 ft
Centroid of Flow Area Yo = 0.26 ft
Specific Force Fs = 0.85 kip
Normal Flow Analysis - Trapezoidal Channel
St. Elizabeth Ann Seton
Existing South Swale
2017.09.13_SEAS EX SOUTH SWALE.xls, Basics 9/12/2017, 3:02 PM
St. Elizabeth Ann Seton Catholic Church Expansion Final Drainage Report September 2017
D
Appendix D: Grading and Erosion Control Plan,
Drainage Plan
COLORADO CIVIL GROUP, INC.
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STAGE-STORAGE SIZING FOR DETENTION BASINS
ST. ELIZABETH ANN SETON
Check Basin Shape
2017.09.13_DETENTION POND.xls, Basin 9/12/2017, 5:28 PM
130 0.48 0.054 0.52 0.07 0.012 0.042 130 1.66 0.212 0.52 0.44 0.078 0.133
135 0.46 0.055 0.52 0.07 0.012 0.043 135 1.62 0.214 0.52 0.44 0.081 0.132
140 0.45 0.055 0.52 0.07 0.013 0.043 140 1.57 0.216 0.52 0.44 0.084 0.131
145 0.44 0.056 0.52 0.07 0.013 0.043 145 1.53 0.218 0.52 0.44 0.087 0.130
150 0.43 0.056 0.52 0.07 0.014 0.043 150 1.49 0.220 0.52 0.44 0.090 0.129
155 0.42 0.057 0.52 0.07 0.014 0.043 155 1.46 0.221 0.52 0.44 0.093 0.128
160 0.41 0.057 0.52 0.07 0.014 0.043 160 1.42 0.223 0.52 0.43 0.096 0.127
165 0.40 0.058 0.52 0.07 0.015 0.043 165 1.39 0.225 0.52 0.43 0.099 0.126
170 0.39 0.058 0.51 0.07 0.015 0.043 170 1.36 0.227 0.51 0.43 0.102 0.125
175 0.38 0.059 0.51 0.07 0.016 0.043 175 1.33 0.228 0.51 0.43 0.105 0.124
180 0.37 0.059 0.51 0.07 0.016 0.043 180 1.30 0.230 0.51 0.43 0.107 0.122
185 0.37 0.059 0.51 0.07 0.017 0.043 185 1.28 0.231 0.51 0.43 0.110 0.121
190 0.36 0.060 0.51 0.07 0.017 0.043 190 1.25 0.233 0.51 0.43 0.113 0.120
195 0.35 0.060 0.51 0.07 0.018 0.043 195 1.23 0.234 0.51 0.43 0.116 0.118
200 0.35 0.061 0.51 0.07 0.018 0.043 200 1.20 0.236 0.51 0.43 0.119 0.117
205 0.34 0.061 0.51 0.07 0.018 0.043 205 1.18 0.237 0.51 0.43 0.122 0.115
210 0.33 0.061 0.51 0.07 0.019 0.042 210 1.16 0.239 0.51 0.43 0.125 0.114
215 0.33 0.062 0.51 0.07 0.019 0.042 215 1.14 0.240 0.51 0.43 0.128 0.112
220 0.32 0.062 0.51 0.07 0.020 0.042 220 1.12 0.241 0.51 0.43 0.131 0.111
225 0.32 0.062 0.51 0.07 0.020 0.042 225 1.10 0.243 0.51 0.43 0.134 0.109
230 0.31 0.063 0.51 0.07 0.021 0.042 230 1.08 0.244 0.51 0.43 0.137 0.108
235 0.31 0.063 0.51 0.07 0.021 0.042 235 1.07 0.245 0.51 0.43 0.139 0.106
240 0.30 0.063 0.51 0.07 0.021 0.042 240 1.05 0.247 0.51 0.43 0.142 0.104
245 0.30 0.064 0.51 0.06 0.022 0.042 245 1.03 0.248 0.51 0.43 0.145 0.103
250 0.29 0.064 0.51 0.06 0.022 0.042 250 1.02 0.249 0.51 0.43 0.148 0.101
255 0.29 0.064 0.51 0.06 0.023 0.041 255 1.00 0.250 0.51 0.43 0.151 0.099
260 0.28 0.065 0.51 0.06 0.023 0.041 260 0.99 0.251 0.51 0.43 0.154 0.097
265 0.28 0.065 0.51 0.06 0.024 0.041 265 0.97 0.252 0.51 0.43 0.157 0.096
270 0.27 0.065 0.51 0.06 0.024 0.041 270 0.96 0.254 0.51 0.43 0.160 0.094
275 0.27 0.065 0.51 0.06 0.025 0.041 275 0.95 0.255 0.51 0.43 0.163 0.092
280 0.27 0.066 0.51 0.06 0.025 0.041 280 0.93 0.256 0.51 0.43 0.166 0.090
285 0.26 0.066 0.51 0.06 0.025 0.040 285 0.92 0.257 0.51 0.43 0.168 0.088
290 0.26 0.066 0.51 0.06 0.026 0.040 290 0.91 0.258 0.51 0.43 0.171 0.086
295 0.26 0.066 0.51 0.06 0.026 0.040 295 0.90 0.259 0.51 0.43 0.174 0.085
300 0.25 0.067 0.51 0.06 0.027 0.040 300 0.88 0.260 0.51 0.43 0.177 0.083
Mod. FAA Minor Storage Volume (cubic ft.) = 1,865 Mod. FAA Major Storage Volume (cubic ft.) = 5,935
Mod. FAA Minor Storage Volume (acre-ft.) = 0.0428 Mod. FAA Major Storage Volume (acre-ft.) = 0.1362
DETENTION VOLUME BY THE MODIFIED FAA METHOD
ST. ELIZABETH ANN SETON
Determination of MAJOR Detention Volume Using Modified FAA Method
(For catchments less than 160 acres only. For larger catchments, use hydrograph routing method)
(NOTE: for catchments larger than 90 acres, CUHP hydrograph and routing are recommended)
UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.34, Released November 2013
Determination of MINOR Detention Volume Using Modified FAA Method
2017.09.13_DETENTION POND.xls, Modified FAA 9/12/2017, 5:27 PM
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 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.
Wind Erodibility Index—Larimer County Area, Colorado
(WIND ERODIBILITY INDEX)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 2 of 3
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
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.
Wind Erodibility Group—Larimer County Area, Colorado
(WIND ERODIBILITY GROUP)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 2 of 3
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
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
(HYDROLOGIC SOIL GROUP)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 2 of 4
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
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.
Drainage Class—Larimer County Area, Colorado
(DRAINAGE CLASS)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
6/24/2017
Page 2 of 3