HomeMy WebLinkAboutDrainage Reports - 09/18/2023FINAL DRAINAGE REPORT
��UNITED CIVIL
Design Group
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PEX- AVEN PARTMENTS
City of Fort Collins Approved Plans
Replat of Lots 1 and 2, The Slab Property Approvedby: WesLamarque
�bservatary Park Subdivisinn �ate: 9/18/2�23
Fart Collins, CO
Prepared far:
Maxiiimo Develnpment and Asset
Management Group, LLC
720/730 West Prospect Road
Fort Collins, C� 80526
Date:
September 2, 2022
19 OLD TOWN SQUARE #238 � FORT COLLINS, CO 80524 � 970-530-4044 � www.unitedciviLcom
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
September 2, 2022
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Apex-Haven Apartments
Fort Collins, Colorado
Project Number: U19031
Dear Staff:
UNITED CIVIL
Design Group
United Civil Design Group, LLC. is pleased to submit this Final Drainage Report for the Apex-Haven Apartments site in Fort
Collins, Colorado. In general, this report serves to document the stormwater impacts associated with the proposed
improvements related to the existing site.
We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria contained in
the Fort Collins Stormwater Criteria Manual (FCSCM). This report was prepared in compliance with technical criteria set forth
in both the Urban Drainage and Flood Control District (UDFCD) Urban Storm Draina�e Criteria Manual and the Fort Collins
Stormwater Criteria Manual.
If you should have any questions or comments as you review this report, please feel free to contact us at your convenience.
Sincerely,
United Civil Design Group
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Colton Beck, PE
Project Engineer
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Kevin Brazelton, PE
Principal
U19031_Drainage Report.docx
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
TABLE �F CONTENTS
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V.
VI
1911
UNITED CIVIL
Design Group
General Location and Description ......................................................................................................................1
A. Location and Project Description ................................................................................................. 1
B. Description of Property ................................................................................................................ 2
C. Floodplains ...................................................................................................................................2
Drainage Basins and Sub-Basins .........................................................................................................................3
A. Major Basin Description ............................................................................................................... 3
B. Sub-Basin Description .................................................................................................................. 3
DrainageDesign Criteria ....................................................................................................................................3
A. Regulations ...................................................................................................................................3
B. Directly Connected Impervious Area (DCIA) ................................................................................ 3
C. Hydrological Criteria ..................................................................................................................... 4
D. Hydraulic Criteria .......................................................................................................................... 4
E. Modifications of Criteria .............................................................................................................. 4
DrainageFacility Design .....................................................................................................................................4
A. General Concept ........................................................................................................................... 4
B. Specific Details ............................................................................................................................. 4
ErosionControl ................................................................................................................................................ 10
Conclusions..................................................................................................................................................... 10
A. Compliance with Standards ....................................................................................................... 10
B. Drainage Concept ....................................................................................................................... 10
C. Stormwater Quality .................................................................................................................... 10
Refere nces ................................................................................................................................................... 11
APPENDICES
APPENDIX A — Hydrology Calculations
APPENDIX B — Hydraulic Calculations
8.1 — Low Impact Development Calculations
8.2 — Water Quality Calculations
8.3 — Detention Pond and Orifice Calculations
8.4 — Inlet Sizing Calcu/ations
8.5 — Storm Pipe Calculations
8.6 — Curb Channel Calculations
8.7 — Weir Calculation
APPENDIX C — Referenced Materials
APPENDIX D — Drainage Exhibits
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I I U19031_Drainage Report.docx
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
GENEI2AL LOCATI�N AND DESCRIPTIDN
A. LOCATION AND PROJECT DESCRIPTION
��� UNITED CIVIL
Design Group
The Apex-Haven Apartments site (referred herein as "the site") is proposed as a replat Lots 1 and 2 of The Slab Property,
located in the southwest quarter of Section 14, T7N, R69W of the 6th P.M., City of Fort Collins, Larimer County, Colorado. The
property, consisting of approximately 2.63 acres, is located immediately north of West Prospect Road, approximately 750-
feet west of South Whitcomb Street and currently exists as a residential property with an apartment complex, two single
family structures and a recently constructed detention pond. The proposed Apex-Haven site improvements are limited to
1.19 acres on the east side of the property, formerly recognized as "Lot 2" of the Slab Property. The recently developed
portion of the property to the west (formerly known as Lot 1) is referred herein as "The Slab" property.
The property is bounded by West Prospect Road to the south, a recently developed apartment complex to the west, a single-
family residence to the east, and an existing apartment complex to the north. Stormwater on the site currently drains
southeast via sheet flow to West Prospect Road and is then conveyed easterly to storm sewer infrastructure associated with
the Old Town master drainage basin.
The proposed development of the site consists of the restoration of two existing on-site single-family residences and the
construction of a new apartment building with a 11,300-sf footprint. Associated with the apartment building and existing
residence improvements are proposed drive lanes, parking, utilities, an underground water quality facility, and improvements
to the existing on-site detention pond. On-site stormwater, both detained and undetained, is largely designed to discharge
to West Prospect Road.
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FIGl1RE �: $ITE VICINITY MAP
This drainage report presents the overall drainage plan for the development. In general, this report serves to provide an
analysis of the drainage impacts associated with the development of site as it relates to existing and proposed drainage
facilities on-site.
1 U19031_Drainage Report.docx
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
B. DESCRIPTION OF PROPERTY
UNITED CIVIL
Design Group
The project site currently exists largely as a gravel and grass/weed landscape, and also includes concrete pavement and
rooftop, comprising of an existing imperviousness of 11.6%. In its historic condition, the site primarily sheet flows in two
general directions: southeast where it is conveyed to West Prospect Road, and off-site to the north and northeast. In its
existing (non-historic) condition, a minor portion of the site drains to a recently constructed detention pond associated with
the development of "The Slab" property to the west. Similar to historic flows, runoff conveyed to the existing detention pond
is ultimately released to West Prospect Road.
Below are summaries of key components of the site in its existing conditions.
Land Use - The site's current land use is residential.
Ground Cover - The site exists with two residential homes with gravel/dirt driveways and surrounding weed/grass
landscaping. The weed/grass cover is good (ie., heavy or dense cover with nearly all ground surfaces protected by
vegetation).
Existing Topography — Historically, the site slopes in two general directions: northeasterly and southeasterly.
Approximately the southern half of the property drains southeasterly to West Prospect Road, and minor portion of
this area drains initially to a recently constructed detention pond associated with the development to the west. The
northern portion of the site drains off-site to the northeast.
Grades — In general, the northern portion of the site is sloped northeasterly at approximately 1.0% to 5.0%; the
southern portion of the site is sloped southeasterly at approximately 1.0% to 10.0%
Soil Type - The USDA's Web Soil Survey shows that the site consists of a"Type B" soil. The Web Soil Survey indicates
the site is comprised of Altvan Santana Loams (0 to 3% slopes). The on-site soils provide moderate infiltration and
are suitable for development.
Utilities — The following dry utility lines run along the south side of the site: gas, electric, cable TV, fiber optic. Water
mains are also present on the south side of the site within West Prospect Road. A recently constructed sanitary
sewer service exists at the northwest portion of the site.
Drainage Features and Storm Sewer — A recently constructed detention pond exists at the southwest corner of the
site, releasing runoff to West Prospect Road immediately to the South.
C. FLOODPLAINS
The proposed development is not in a FEMA designated
floodplain. According to the FEMA Flood Insurance Rate Map
Panel, the site is zoned as an area outside of the 500-year
floodplain. The FEMA FIRM Map is included in the appendix.
FIGURE 2: FL��DPLAIN MAP
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APEX-HAVEN APARTMENTS
FORT COLLINS, CO
I I. DRAINAGE BASINS AND Sl1B-BASINS
A. MA10R BASIN DESCRIPTION
��� UNITED CIVIL
Design Group
The proposed development is located within the Old Town Basin, located primarily in Old Town Fort Collins. No known master
planning improvements are associated with or adjacent to the site.
B. $UB-BASIN DESCRIPTION
"The Slab" portion of the property, formerly recognized as Lot 1, was previously analyzed in a Final Drainage Report entitled
"The Slab," dated September 21, 2016 by Northern Engineering. The development of this area provided the addition of
concrete drives, and sidewalks. Improvements also included a detention pond on the Apex-Have site (formerly known as Lot
2). This recently constructed pond is re-analyzed in conjunction with the proposed on-site improvements.
In its developed condition, runoff from the site will largely be directed south to the on-site detention pond either via overland
flow to surface improvements or via proposed storm sewer. Due to site grading constraints, a portion of the site will continue
to drain directly to West Prospect Road undetained. A minor portion of the site — a largely decreased area relative to historic
conditions — is designed to continue draining off-site to the north and northeast.
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DRAINAGE DE51GN CRITERIA
REGULATIONS
The design criteria for this study are directly from the City of Fort Collins Storm Drainage Design Criteria and Construction
Standards Manual and the Urban Storm Drainage Criteria Manuals Volumes 2, and 3(referred to herein as USDCM).
B. DIRECTLY CONNECTED IMPERVIOUS AREA �DCIA�
With the adoption of the USDCM, the City has also adopted the "Four Step Process" that is recommended in Volume 3 of
the USDCM in selecting structural BMPs for the redeveloping urban areas. The following portions of this summary describe
each step and how it has been utilized for this project:
Step 1— Employ Runoff Reduction Practices
The objective of this step is to reduce runoff peaks and volumes and to employ the technique of "minimizing directly
connected impervious areas" (MDCIA). This project accomplishes this by:
Routing the roof and pavement flows through a bioretention facility, underground water quality treatment/infiltration
facilities and vegetated swales to increase time of concentration, promote infiltration and provide water quality.
Step 2— Provide Water Quality Capture Volume (WQCV)
The objective of providing WQCV is to reduce the sediment load and other pollutants that exit the site. For this project
WQCV is provided within underground treatment facilities and a bioretention pond.
Step 3 — Stabilize Drainageways
The site is not adjacent or near a major drainageway; however, this project will pay stormwater development and
stormwater utility fees which the City uses, in part, to maintain the stability of the City drainageway systems.
Step 4— Consider Need for Site Specific and Source Control BMPs
Site specific and source control BMPs are generally considered for large industrial and commercial sites. The
redevelopment of the existing site will include multiple site specific and source controls, including:
• Dedicated maintenance personnel providing landscape maintenance and snow and ice management.
Dedicated dog park.
U19031_Drainage Report.docx
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
C. HYDROLOGICAL CRITERIA
��� UNITED CIVIL
Design Group
City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, provided by Figure RA-16 of the Fort Collins Stormwater
Criteria Manual, are utilized for all hydrologic computations related to the site in its existing/historic and proposed conditions.
Since this site is relatively small and does not have complex drainage basins, the peak flow rates for design points have been
calculated based on the Rational Method as described in the USDCM and the City of Fort Collins Stormwater Criteria Manual
(FCSCM) with storm duration set equal to the time of concentration for each sub-basin. This method was used to analyze the
developed runoff from the 10-year (minor) and the 100-year (major) storm events. The Rational Method is widely accepted
for drainage design involving small drainage areas (less than 160 acres) and short time of concentrations. Runoff coefficients
are assumed based on impervious area and are given in the Appendices.
D. HYDRAULIC CRITERIA
The developed site will convey runoff to the proposed pond or underground treatment facility via swales, concrete channels,
and pipes. The City of Fort Collins Stormwater Criteria Manual (FCSCM) and USDCM are referenced for all hydraulic
calculations. In addition, the following computer programs are utilized:
• Storm Sewer Extension for AutoCAD Civi13D
• Hydraflow Express Extension for AutoCAD Civi13D
• UD-Inlet by UDFCD
Drainage conveyance facility capacities proposed with the development project, including storm sewer, swales, and inlet
capacities, are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control
District's Urban Storm Drainage Criteria Manual (UDFCD).
E. MODIFICATIONS OF CRITERIA
Hardships related to a lack of public storm sewer adjacent to the site and the limited number of solutions available to the site
due to the historic preservation requirements of existing on-site residences present difficulties in limiting the release of on-
site runoff to the historic 2-year event. A separate variance request has been submitted to allow a design of the proposed
site that provides runoff release to West Prospect Road, in addition to release off-site the north, at values that do not exceed
the historic 100-year condition. Moreover, a bioretention pond related to the site improvements is designed with a 6-in
bioretention media section, as opposed to a standard 18-in section per City of Fort Collins standards. Finally, due to area
constraints associated with maintaining existing trees adjacent to Pond B, the detention volume for the pond is inclusive of
the water quality volume required for the basin.
IV. DRAINAGE FACILITY DESIGN
A. GENERAI CONCEPT
Developed runoff is designed to be conveyed in a safe and effective manner via swales, concrete channels, and storm sewer
systems/inlets. Stormwater is designed to be released to West Prospect Road at a rate equivalent to the 100-year historic
flow rate. Runoff that drains off-site to the north is heavily reduced with the proposed site; runoff from the site in its improved
condition is primarily conveyed to bioretention, detention, and underground water quality facilities, all of which are designed
at the southern end of the property. Due to grading constraints, not all on-site runoff is fully detained - these areas are
considered in the overall release rate from the site.
B. $PECIFIC DETAILS
Hvdrology
As previously stated, hydrology from the developed site is designed to comply with criteria set forth in the City of Fort Collins
Stormwater Criteria Manual with exception of the modifications stated in the "Modification of Criteria" section. Referenced
tables, charts, formulas, etc. are included in the appendices. The area, time of concentration, and runoff of each proposed
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APEX-HAVEN APARTMENTS UNITED CIVIL
FORT COLLINS, CO Design G�-oup
sub-basin is summarized in Appendix A. The following information outlines the basin characteristics and drainage patterns
for each basin.
On-site Basins
The following basins provide proposed drainage delineations for the site in its improved condition. Note that Basins S1 and
ON1 are per "The Slab" report by Northern Engineering. Refer to Appendix A for hydrology computations and Appendix B for
calculations related to Detention, Water Quality, Low Impact Development, and other hydraulic features.
Basin A
Sub-basins A1-A3 (see Drainage Plan attached) are generally located around the south and southeast region of the site. These
basins consist of roofs, concrete paving, and landscaping. Runoff within these Basins is conveyed to an underground water
quality system (Pond A) via inlets and downspouts. Runoff conveyed to the underground water quality system is ultimately
discharged southeast of the site to West Prospect Road via a concrete curb channel.
Basin B
Sub-basins B1-B3 represent on-site drainage basins where runoff is captured and conveyed to an on-site bioretention and
detention pond (Pond B). These basins consist of roofs, concrete paving and landscaping. Sub-basin 61 largely consists of the
pond area - runoff within this area drains directly to the pond via sheet flow or by means of storm sewer related to "The Slab"
property. Runoff within sub-basin B2 is conveyed to the Pond B via curb and a concrete channel, and runoff within sub-basin
B3 is conveyed to Pond B via a roof drain system. The proposed pond area is designed to receive flows from "The Slab"
property immediately west of the site, however, these flows are treated by upstream, off-site infrastructure. An outlet
structure is proposed with the mentioned pond and is designed to release stormwater to West Prospect Road.
Basin C
Sub-basins C1 and C2 consists primarily of roofing, concrete walks, and landscaped area. Runoff within these basins is
conveyed to a proposed detention pond (Pond C) via sheet flow and storm sewer/roof drains.
Basin D
Sub-basins D1 and C2, consists primarily of landscaped area and concrete pavement. Due to grading constraints, runoff
developed within these basin drains off-site undetained to the south and southeast via sheet flow.
Basin E
Basin E1, similar to Basins D1 and D2, consists primarily of landscaped area concrete pavement. Due to grading constraints,
runoff developed within this basin drains off-site undetained to the north and northeast via sheet flow.
Basin ON1
Basin ON1 is a drainage basin associated with the design and construction of "The Slab" property, per the Northern
Engineering Final Drainage Report. This approved drainage report provided a design with runoff draining off-site to the north.
The on-site improvements are expected to have negligible impact on the original design of Basin ON1.
Basin S1
Basin S1 is a drainage basin associated with the design and construction of "The Slab" property, per the Northern Engineering
Final Drainage Report. This approved drainage report provided a design with runoff draining further on-site form the west.
The on-site improvements are expected to have negligible impact on the original design of Basin S1.
Stormwater Quality
Underqround Water Quality
An underground water quality facility is designed to divert storm water runoff during the water quality event and
treat the flows through infiltration prior to being collected within an underdrain system. This provides for the
removal of sediment and other pollutants from the runoff while also promoting infiltration. Underground water
U19031_Drainage Report.docx
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
UNITED CIVIL
Design Group
quality chambers are designed to collect and treat storm water runoff from Basins A1-A3 and Basins C1-C2 prior to
being released to West Prospect Road.
The underground water quality system, designated as "Pond A" is designed with a volume of 248-cf which exceeds
the minimum design requirements for the area (195-cf). Below is a summary table for water quality related to all
"A" and "C" Basins. Refer to Appendix B for additional information.
WQCV WQCV WQ
Pond Required Provided Release Rate
(cf) (cf) (cfs)
Pond A 195 248 0.13
Bioretention
Bioretention is designed to remove sediment and pollution from stormwater runoff via infiltration through an
engineered sand media. This slows the conveyance rate of storm water runoff, reduces runoff and provides a flow
path across a vegetated surface. A bioretention pond is proposed with the site improvements and is utilized to
convey and treat stormwater prior to release to West Prospect Road.
The proposed bioretention pond, a reconstruction of the existing detention pond, is designed to maintain its existing
top-of-pond elevation per "The Slab" Final Drainage Report. Moreover, the pond in its existing condition is designed
to overflow to the south in West Prospect Road — the overflow weir will remain as designed despite reconstruction.
Per "The Slab" report, the original pond was designed with excess capacity of approximately 3,000-cf for detention;
however, the proposed site improvements require detention of a significantly larger volume due to the extent of
growth in impervious area relative to historic conditions. Therefore, an expansion in the size of the constructed pond
is necessary for the managing of developed stormwater in a safe and effective manner.
The proposed bioretention pond is designed to provide about 1,040-sf of bioretention area and is located at the
bottom of the detention pond. Provided six inches of depth, approximately 495-cf of the pond's volume is specifically
intended for bioretention purposes — this volume exceeds the required WQCV for Basins 61-63 (372-cf). Ponding
above the initial six inches of pond depth is intended for detention purposes further discussed in the report. Below
is a summary of the bioretention pond, recognized as Pond B:
Bioretention Volume Bioretention Volume
Pond Bottom of Bioretention Required Provided
Pond Elevation WSEL (cf) (cf)
Pond B 5022.50 5023.00 372 495
Low Impact Development (LID)
In December of 2015, Fort Collins City Council adopted the revised Low Impact Development (LID) policy and criteria which
requires developments within City limits to meet certain enhanced stormwater treatment requirements in addition to more
standard treatment techniques. The proposed development will be required to meet the newly adopted LID criteria which
requires the following:
- Treat no less than 75% of any newly added impervious area using one or a combination of LID techniques.
- Treat no less than 50% of any newly added impervious area using one or a combination of LID techniques when at
least 25% of any newly added pavement is provided with permeable pavement.
The following measures are implemented with this proposed development:
Underpround Water Quality
Basins A1-A3 and C1-C2, combined for 7,406-sf of proposed impervious area, are designed to be routed through an
underground water quality system located in the southeastern portion of the site. The proposed impervious area
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FORT COLLINS, CO
��� UNITED CIVIL
Design Group
treated through underground water quality includes existing and proposed roof areas. The underground water
quality system is designed with an overall capacity of 248-cf which exceeds the minimum design requirements for
the area. Refer to Appendix B for additional information.
Bioretention
Basins B1-B3, with 13,979-sf of proposed impervious area, are designed to be conveyed to a Pond B, a proposed
bioretention facility. The proposed impervious area treated through bioretention includes existing roof areas.
Approximately 1,040-sf of the pond with six inches of depth is designed specifically for water quality.
Without the use of permeable pavement, the site is required to treat no less than 75% of added impervious area. Provided
the LID measures noted above, approximately 92% of the site is treated in its improved condition. Refer to Appendix B for
calculations
Detention
Pond A
The design of Pond A is intended for underground water quality purposes; underground detention is not considered
with the site improvements. In the 100-year event, runoff conveyed to the underground water pond is designed to
bypass the facility and be released at the improved site's 100-year flows (0.52-cfs).
11. Pond 8
As mentioned in the above section regarding the bioretention pond, ponding depth above the six inches of depth
designed for bioretention is reserved for detention purposes. Due to site and grading constraints, the 100-yr event
design capacity includes the volume typically utilized for water quality purposes. The required detention volume for
Pond B is a function of both the cumulative impact of impervious areas associated with the pond, and the overall
release rate to West Prospect Road. The designed volume of the detention is 6,788cf — this volume exceeds that of
the required volume for drainage basins related to Pond B(Basins 61-63 in addition to a 0.49-ac basin conveyed to
the Pond from "The Slab" property per the Northern Engineering Report). Runoff in an event that exceeds the 100-
yr storm is designed to drain to West Prospect Road via a reconstructed emergency overflow weir similar to that of
what was designed and constructed with "The Slab" property's detention pond. Below is a summary of the detention
feature related to Pond B:
Detention Volume Detention Volume 100-yr
Pond Bottom of Detention Top of Pond Required Provided Release Rate
Pond WSEI Elevation (cfs) (cf) (cfs)*
Pond B 5022.50 5026.00 5026.60 6,428 6,788 0.85
* 0.85-cfs includes 0.30-cfs of treated runoff from the Slab Property, not included in the cumulative "on-site' release to West Prospect Road
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��� UNITED CIVIL
Design Group
111. Pond C
A proposed detention system is associated with Basins C1 and C2. This system is designed to release captured runoff
within at a rate of 0.28-cfs in the 100-yr event. This release rate is controlled by its relationship with the site's overall
release rate to West Prospect Road (see the following page). Smaller storm events (i.e. water quality events) are
designed to pass through the pond without any significant storage in the pond. To reduce the risk of stormwater
infiltrating from the pond during larger storm events and into the adjacent basement of Building 3 and/or
neighboring properties, the pond will be lined with a minimum of a 30-mil PVC liner outside of the wall limits (Refer
to the Construction Plans for a pond wall detail). Additionally, to further protect Building 3, a foundation drain with
a sump pump located in the basement of the building will be provided. For emergency situations, the pond is
designed to spill stormwater through the emergency overflow structure which is located at the southeast corner of
the pond wall. Water discharged from the emergency overflow will be directed via an onsite drainage swale from
the overflow location to the eastern property line south of Building 3 and south of the existing residence east of the
site. Once at the property line, water will be conveyed along the property line to West Prospect Road.
Below is a summary of Pond C utilizing the FAA method:
Detention Volume Detention Volume 100-yr
Pond Required Provided Release Rate
(cf) (cf) (cfs)
Pond C 788 1,080 0.28
Draina�e Summary
A basin summary table is included below:
.
Basin Area %I
(acre)
EX1 0.64 15.9%
EX2 0.55 11.6%
Cz Cioo Qz Qioo
(cfs) (cfs)
0.35 0.44 0.50 2.29
0.32 0.40 0.38 1.64
Totals 0.88 3.93
.�. -�
Basin Area %I Cz C�oo QZ Q�oo
(acre) (cfs) (cfs)
A1 0.02 90.0% 0.95 1.00 0.05 0.19
A2 0.03 34.7% 0.51 0.64 0.05 0.20
A3 0.01 90.0% 0.95 1.00 0.03 0.12
61 0.19 16.7% 0.37 0.46 0.17 0.76
B2 0.25 68.3% 0.76 0.95 0.55 2.40
B3 0.13 90.0% 0.95 1.00 0.35 1.27
C1 0.05 25.6% 0.44 0.55 0.06 0.26
C2 0.13 90.0% 0.95 1.00 0.36 1.31
D1 0.13 25.2% 0.42 0.52 0.14 0.66
D2 0.06 2.0% 0.25 0.31 0.04 0.17
E1 0.09 17.6% 0.37 0.47 0.09 0.41
S1 0.04 48.9% 0.62 0.78 0.07 0.31
ON1 0.06 42.4% 0.57 0.71 0.10 0.44
Totals 2.06 8.52
�
� �
g U19031_Drainage Report.docx
FINAL DRAINAGE REPORT UNITED CIVIL
APEX-HAVEN APARTMENTS
FORT COLLINS, CO Design Group
Refer to Appendix D for a Historic Drainage Exhibit that provides a visual representation of Historic Basins EX1 and EX2. In its
improved condition, the total release of on-site runoff to West Prospect Road is designed not to exceed the historic 100-yr
condition (e.g. Basin EX1). Similarly, on-site runoff that drains off-site to the north is improved in the 100-yr event. Below are
summary tables of the on-site runoff release in the 100-yr event:
100-yr Event: On-site release to We<_
Basin/Pond Release Rate
Designation (cfs)
Basin EX1 2.29
*Slab Property 0.30
Existing Release 2.59
Basin D1 0.66
Basin D2 0.17
Pond A 0.52
Pond B 0.85
Pond C 0.28
Proposed Release 2.48
t Prospect Road
* Runoff drained to Pond B from "The Slab" property per the Northern
Engineering report is included in the Pond B release; however, this flowrate
(0.30-cfs) is not included in "on-site" release calculations.
100-yr Event: On-site release to Nor
Basin/Pond Release Rate
Designation (cfs)
Basin EX2 1.64
Existing Release 1.64
Basin E1 0.41
Basin ON1 0.44
Proposed Release 0.85
Standard Operatin� Procedures (SOPs)
In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is essential.
Maintenance includes both routinely scheduled activities, as well as non-routine repairs that may be required after large
storms, or as a result of other unforeseen problems. Standard Operating Procedures should clearly identify BMP maintenance
responsibility. BMP maintenance is typically the responsibility of the entity owning the BMP.
Identifying who is responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for maintenance
is critical to the long-term success of BMPs. Maintenance responsibility may be assigned either publicly or privately. For this
project, the privately owned BMPs including grass swales, underground water quality and detention, and the bioretention
pond, are to be maintained by the property owner.
Storm Sewers
There are multiple storm sewer networks proposed with the site improvements. Related to conveyance of runoff to the
bioretention pond, multiple roof drain systems interconnected with an outfall to the bioretention pond. Other roof drains,
storm drains, and underground water quality features are interconnected with an outfall to West Prospect Road. All storm
sewers will be private and are sized to accommodate the flows from the 100-year storm event. Hydraulic computations of
these systems will be provided within Appendix B.
Inlets
There are multiple inlets proposed with the site improvements, including nyloplast drain basins and a Type R inlet. The Type
R Inlet is designed on-grade to capture runoff developed within Basin A1. On-site drain basins are designed in a sump
condition and are designed to convey runoff produced within smaller interior basins to the underground detention system.
All inlets on the site are sized to provide adequate capacity and convey the 100-year storm event. Hydraulic computations
of these systems will be provided within Appendix B.
9 U19031_Drainage Report.docx
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
v. ERosiaN CaNTRa�
��� UNITED CIVIL
Design Group
A separate Erosion Control Report / Storm Water Management Plan (SWMP) will be prepared for the site in accordance with
the Stormwater Discharge Permit for Colorado Department of Public Health and Environment as the site will disturb an area
greater than 1-acre. The Erosion Control Report is provided with the Final Compliance phase of the project and includes more
detailed information on the sediment and erosion control items for this project. It is intended that the proposed
improvements will comply with Erosion Control Criteria per the FCSCM, and all Erosion Control Materials are provided with
the Final Drainage Report. At a minimum, the following temporary BMP's will be installed and maintained to control on-site
erosion and prevent sediment from traveling off-site during construction:
• Silt Fence — a woven synthetic fabric that filters runoff. The silt fence is a temporary barrier that is placed at the base
of a disturbed area.
• Vehicle Tracking Control — a stabilized stone pad located at points of ingress and egress on a construction site. The
stone pad is designed to reduce the amount of mud transported onto public roads by construction traffic.
• Riprap — Riprap will be used downstream of all storm sewer outfalls to control erosion of the receiving channels.
• Inlet Protection — acts as a sediment filter. It is a temporary BMP and requires proper installation and maintenance
to ensure their performance.
• Straw Wattles — wattles act as a sediment filter in swales around inlets. They are a temporary BMP and require
proper installation and maintenance to ensure their performance.
• Slope Protection —Slopes should be terraced using a"tracked" vehicle, run perpendicular to slope to inhibit rill/gulley
erosion.
The contractor shall store all construction materials and equipment and shall provide maintenance and fueling of equipment
in confined areas on-site from which runoff will be contained and filtered. Temporary Best Management Practices (BMP's)
will be inspected by the contractor at a minimum of once every two weeks and after each significant storm event.
VI. C�NCLUSIONS
A. COMPLIANCE WITH $TANDARDS
Storm drainage calculations have followed the guidelines provided by the Urban Storm Drainage Criteria Manuals Volumes
1, 2 and 3 and the City of Fort Collins Stormwater Criteria Manual.
B. DRAINAGE CONCEPT
The drainage system has been designed to convey the runoff to the designated design points and the existing public
infrastructure in an effective, safe manner. No negative impacts are anticipated to the City of Fort Collins Master Drainage
Plan or to downstream properties or infrastructure due to the proposed improvements.
C. $TORMWATER QUALITY
Multiple long-term stormwater quality measures have been selected for the site that will provide treatment of stormwater
prior it to being discharged from the site. For this site this includes grass swales, a bioretention pond, and underground water
quality.
1� U19031_Drainage Report.docx
FINAL DRAINAGE REPORT
APEX-HAVEN APARTMENTS
FORT COLLINS, CO
VII. REFERENCES
��� UNITED CIVIL
Design Group
1. Citv of Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, November 2017.
2. Urban Storm Draina�e Criteria Manual Volume 1 and 2, Urban Drainage and Flood Control District, Denver, Colorado,
June 2001, Revised April 2008.
3. Final Draina�e Report for The Slab, Northern Engineering, Fort Collins, Colorado, September 2016.
4. Final Draina�e Report for Observatory Park, DMW Civil Engineers, Fort Collins, Colorado, August 2007.
5. Natural Resources Conservation Service Web Soil Survey at: websoilsurvey.nres.usda.gov/app
6. Preliminary Flood Insurance Rate Map, FEMA, Panel 2079E, https://hazards.fema.gov/femaportal/
7. Stormwater Discharges Associated with Construction Activity, Stormwater Management Plan Preparation Guides, State
of Colorado, www.colorado.com
11 U19031_Drainage Report.docx
PPENDIX
HYDROLOGY CALCl1LATI0NS
Rl1N�FF COEFFICIENTS AND % IMPERVI011S
' ��� •� �
Basin Oesign Pt. Meas Composite NRCS 5oil Com osite Runnff Coefficients
Total Total Roof ��� Asphalt Canerete°� Permea6le �Wns�° Imperviousness Type �z �ioo
Paveme�
acres sl %I = 90% %I =10U% %I = 90% %I =40% %1=2% (%q
s/ sf s/ sf sf
A1 A1 0.02 849 849 - - 90.0% 0.95 1.00
qz qz 0.03 1,393 518 - 875 34.7% 0.51 0.64
A3 A3 0.01 525 525 - - - 90.0% 0.95 7.00
Bl Bl 0.19 8,260 745 631 - 6,884 16.7% 037 0.46
g2 g2 0.25 11,107 982 2,693 4,385 - 3,047 683% OJ6 0.95
B3 B3 0.13 5,576 5,576 - - - 90.0% 0.95 1.00
C1 Cl 0.05 2,076 460 96 - 1,520 25.6% 0.44 0.55
Q Q 0.13 S,RB 5,728 - - - 90.0% 0.95 1.00
D1 DI 0.13 5,495 1,060 270 - 4,165 25.2% 0.42 0.52
D2 D2 0.06 2,735 - - 2,735 2.0% 0.25 0.31
E1 E1 0.09 3,840 682 - 3,158 17.6% 0.37 0.47
Sl Sl 0.04 1,760 937 - 823 48.9% 0.62 0.78
ON1 ONS 0.06 2,708 1,161 I88 1,359 42.4% 0.57 0.71
Pro osed Total 1.19 52,052 14,016 3,753 9,529 188 24,566 49.OY 0.62 0.77
Notes:
(1) Recommended % Imperviousness Values per USDCM Volume 1, Table 6-3.
(2) Runoff C is based on %I and NRCS soil group per UDFCD Volume 1, Table 6-4.
Date: 12/9/2020 C�United Civil Dropbox�Projects�U19031 - Haven Apartments�Reports�Di
Apex-Haven Apartments, Fort Collins, C�
Y-YEAR TIME OF C�NCENTRATION
nts. Fart Callins, CO
' ��� •� �
Basin esign t. rea Travel/Channelized Time of Flow (t�) t� Check (or Urbanized 8asins
C��� Length 31ope t«� Length 51ope �� Velo�ity�3� t�u� t;+t, Checkt�7 TotalLength t��s� Finalt��s)
acres ft % min k % f s min min Urban? h min min
A1 A1 OD2 ��95 60 4.0% 1�3 10 5.5% 20 4.7 0.0 1.4 Yes 70 10 5.0
A2 A2 0.03 0.51 25 5.0% 3�1 105 4.0% 15 3.0 0.6 3.7 Yes 130 11 5.0
A3 A3 0.01 0.95 45 6.0% 1.0 zp z,p� zp 2.8 0.1 1.1 Yes 65 10 5.0
Bl Bl 0.19 0.37 75 5.0% 6�� SS 0.5% 15 1.1 0.9 7.6 Yes 130 11 7.6
62 62 0.25 0.76 40 3.5% Z�6 125 0.5% 20 1.4 1.5 4.1 Yes 165 11 5.0
B3 83 0.13 0.95 30 2.0% 1�Z 100 0.5% 20 1.4 1.2 2.4 Yes 130 11 5.0
C1 C1 0.05 0.44 45 6.0% 4�4 55 0.5% 15 1.1 0.9 53 Yes 100 11 53
C2 C2 0.13 0.95 30 2.0% l�Z 100 0.5% 20 1.4 1.2 2.4 Yes 130 11 5.0
Di D1 0.13 0.42 25 5.0% 3�6 135 0.5% 15 1.1 Z.1 5.7 Yes 160 11 5.7
D2 D2 0.06 0.25 50 3.5% ��Z 35 2.0% 15 Z.1 03 7.5 Yes 85 10 7.5
E1 E1 0.09 037 15 5.5% Z�9 130 22% 15 2.z 1.0 3.9 Yes 145 ll 5.0
Sl Sl 0.04 0.62 30 2.5% 3�5 100 4.7% 20 43 0.4 3.9 Yes 130 11 5.0
ON1 ON1 0.06 0.57 20 5.0% 2�5 60 0.5% 20 1.4 0.7 3.2 Yes 80 10 5.0
Notes:
ii� �_� ,�
���t, _[1.87(1.1-C,C��L'��]/S'", 5= slope in %, L=length of overland flow (300' max)
�3�V=C�S°�5, 5=watercourse slope in ft/ft, UDFCD Equation RO-4
�4�t� L/(V*60 sec/min)
�S�t� check (for urban or developed areas only) = total length/180 + 10
�fi�min t� = 5 min
Date: 12/9/2020 C:�United Civil Dropbox�Projects�U19031 - Haven Apartments�Reports�Drain
100-YEAR TIME OF CONCENTRATION
nts. Fart Callins, CO
' ��� •� �
Basin esign t. rea Travel/Channelized Time of Flow (t�) t� Check (or Urbanized 8asins
C��� Length 31ope t«� Length 51ope �� Velo�ity�3� t�u� t;+t, Checkt�7 TotalLength t��s� Finalt��s)
acres ft % min k % f s min min Urban? h min min
A1 A1 0.02 1��� 60 4.0% ��9 10 5.5% 20 4.7 0.0 0.9 Yes 70 10 5.0
A2 A2 0.03 0.64 25 5.0% Z�5 105 4.0% 15 3.0 0.6 3.0 Yes 130 11 5.0
A3 A3 0.01 1.00 45 6.0% ��� 20 2.0% 20 Z.$ 0.1 0.8 Yes 65 10 5.0
Bl Bl 0.19 0.46 75 5.0% 5�9 SS 0.5% 15 1.1 0.9 6.8 Yes 130 11 6.S
62 62 0.25 0.95 40 3.5% 1�Z 125 0.5% 20 1.4 1.5 2.6 Yes 165 11 5.0
B3 83 0.13 1.00 30 2.0% ��g 100 0.5% 20 1.4 1.2 2.0 Yes 130 11 5.0
C1 C1 0.05 0.55 45 6.0% 3�� 55 0.5% 15 1.1 0.9 4.6 Yes 100 11 5.0
C2 C2 0.13 1.00 30 2.0% ��g 100 0.5% 20 1.4 1.2 2.0 Yes 130 11 5.0
Di D1 0.13 052 25 5.0% 3�1 135 0.5% 15 1.1 Z.1 5.2 Yes 160 11 5.2
D2 D2 0.06 031 50 3.5% 6�6 35 2.0% 15 Z.1 03 6.9 Yes 85 10 6.9
E1 E1 0.09 0.47 15 5.5% Z�5 130 22% 15 2.z 1.0 3.5 Yes 145 ll 5.0
Sl Sl 0.04 0.75 30 2.5% Z�4 100 4.7% 20 43 0.4 2.7 Yes 130 11 5.0
ON1 ON1 0.06 0.71 20 5.0% 1�9 60 0.5% 20 1.4 0.7 2.6 Yes 80 10 5.0
Notes:
ii� �_� ,�
���t, _[1.87(1.1-C,C��L'��]/S'", 5= slope in %, L=length of overland flow (300' max)
�3�V=C�S°�5, 5=watercourse slope in ft/ft, UDFCD Equation RO-4
�4�t� L/(V*60 sec/min)
�S�t� check (for urban or developed areas only) = total length/180 + 10
�fi�min t� = 5 min
Date: 12/9/2020 C:�United Civil Dropbox�Projects�U19031 - Haven Apartments�Reports�Drain
RATIDNAL METHOD PEAK Rl1N�FF
nts. Fart Callins, CO
' ��� •� �
Basin Design Pt. Area 2-Year 10�-Year Runoff Coeffieients Rainfalllntensity Peak Diseharge
acre t� t� CZ Cioo �2 �mo Qz Omo
min min in/hr in/hr cfs cfs
A1 A1 0.02 5 5 0.95 1.00 2.55 9.95 0.05 0.19
A2 A2 0.03 5 5 0.51 0.64 2.85 9.95 0.05 0.20
A3 A3 0.01 5 5 0.95 1.00 2.55 9.95 0.03 0.12
B1 B1 0.19 8 7 037 0.46 2.40 8.80 0.17 0.76
B2 82 0.25 5 5 0.76 0.95 2.85 9.95 0.55 2.40
63 63 0.13 5 5 0.95 1.00 2.85 9.95 0.35 1.27
Cl Cl 0.05 5 5 0.44 0.55 2.55 9.95 0.06 0.26
Q C2 0.13 5 5 0.95 1.00 2.85 9.95 0.36 131
Dl Dl 0.13 6 5 0.42 0.52 2.67 9.95 0.14 0.66
D2 D2 0.06 7 7 025 0.31 2.52 8.80 0.04 0.17
El El 0.09 5 5 037 0.47 2.55 9.95 0.09 0.41
Sl 51 0.04 5 5 0.62 0.78 2.85 9.95 0.07 031
ONl ON1 0.06 5 5 0.57 0.71 2.85 9.95 0.10 0.44
Totals z.o5 s.s2
Date: 12/9/2020 C:�United Civil Dropbox�Projects�U19031 - Haven Apartments�Reports�Drain
PPENDIX
HYDRAl1LIC CALCl1LATI0NS
LOW IMPACT DEVELOPMENT SLIMMARY
Apez-Haven Gpartments. Fort Collins, C�
Basin Proposed
Impervious Area
N1
764
484
473
1,376
7,584
5,018
531
5,155
1,386
55
677
860
1,147
LID Treatment
Underground Water Quality
Underground Water Quality
Underground Water Quality
Bioretention
Bioretention
Bioretention
Underground Water Quality
Underground Water Quality
None
None
None
Bioretention
Offsite Infiltration System
Area Treated % of Site Treated
764
484
473
1,376
7,584
5, 018
531
5,155
860
1,147
Date: 12/9/2020 C: �United Civil Dropbox�Projects�U19031 - Haven Aportments�Reports�Drain
WATER QIJALITY f�„ UNITED CIVIL
Apez-Haven Gpartments, Fort Collins, C� /'�� Design Graup
(2) Water quality provided by bioretention and based on 12-hour storage
(3) Basins D and E free release from the site
Date: 12/9/2020 C: �United Civil Dropbox�Projectsl U19031 - Haven Aportments�Reports�Drainoge�Calculotions�U19031-Drain Calcs-Revised Site.xlsm
(1) Water quality provided by underground detention and based on 12-hour storage
DETENTION POND WLIJME (FAA Method) � UNITED CIVIL
Apez-Haven Gpartments. Fort Collins, C� Design Graup
asin araeateristies
Area = 10,571 squarefeet
Area = 024 acres
CZ = 0J9
Q;� = 0.55 cfs
e ease ate etermine ram um er o am ers an am er e ease ate
Q our = 0.13 cfs
Unit Flow = 0.52 cfs/acre
T� = 0.0 minutes
Notes:
1. Release rate out of pond based on number of chambers multiplied by release rate per chamber.
2. Rainfall intensities approximated as one-half the 2-yr peak runoff rate.
3. CZ utilized for water quality event detention calculation.
4. Pond is designed to provide WQ for all "A" and "C" Basins.
etentian o ume a eu atians
Rainfall Rainfall Inflow Rate
Duration (T) Intensity Q) Q;� FCloo*Area*I
min
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
in/hr
1.425
1.105
0.935
0.805
0.715
0.650
0.585
0.535
0.495
0.460
0.435
0.410
0355
0365
0345
0330
0315
0305
0190
0.280
0.270
0.260
0.255
0.245
cfs
03
0.2
0.2
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.0
0.0
0.0
V�,=(Q�,�*T*60) Factor
m= OS(1 + T�/T)
82
127
162
186
206
225
236
247
257
265
276
283
288
294
29S
304
309
316
317
323
327
330
33S
339
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
Average
Outflow Rate
�� = m `4o�t
cfs
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.06
�utflow Volume Required
Vo Qa�*T *60 Storage Volume
Vs V� Vo
19
38
57
75
94
113
132
151
170
189
208
226
245
264
283
302
321
340
359
377
396
415
434
453
63
90
105
110
112
111
104
96
87
76
6S
57
43
30
15
2
12
-23
41
-55
70
-86
96
114
equire ater ua ity o ume
�ioo = 112 cubicfeet
�ioo = 0.00 acre-ft
Date: 12/9/2020 C: �United Civil Dropbox�Projectsl U19031 - Haven Aportments�Reports�Drainoge�Calculotions�U19031-Drain Calcs-Revised Site.xlsm
DETENTION POND WLIJME (FAA Method) � UNITED CIVIL
Apez-Haven Gpartments. Fort Collins, C� Design Graup
100 Year Storm Into Detention Facility
Area = 2,767 squarefeet
Area = 0.06 acres
�iao = 0.82
Release Rate �ut of Pond
Q o�7 = o.sz cfs
Unit Flow = 5.12 cfs/acre
Notes:
1. Release Rate mntrolled by 100-year historic flow rates from site to Prospect Avenue and includes 01 cfs from Pond Cl.
2. Area analyzed Indudes Basins Al-A3.
3. Pond is designed to provide WQfor all "A" and "C" Basins
Uetention Volume Caloulations
Rainfall Rainfall Inflow Rate Inflow Volume Adjustment
Duration (T) Intensity (q Q;� ECioo*Area*I V,=(Q,�*T*60) Factor
m= 0.5(1 + T�/T)
min
5
10
15
20
25
30
35
40
45
50
55
60
70
80
90
100
110
120
Average
Outflow Rate
�� = m"Qo��
cfs
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
0.52
Outflow Volume Required
Vo Qa�*T *60 Storage Volume
v� v, vo
155
310
464
619
774
929
1,OS4
1,238
1,393
1,548
1,703
1,858
2,167
2,477
2,786
3,096
3,406
3,715
0
-69
160
-270
386
-506
639
-772
-908
1,045
-1,183
1,323
-1,602
1,883
-2,167
2,454
-2,741
Required Detention Volume
�ioo = 0 cubicfeet
�ioo = 0.00 acre-ft
Date: 12/9/2020 C: �United Civil Dropbox�Projectsl U19031 - Haven Aportments�Reports�Drainoge�Calculotions�U19031-Drain Calcs-Revised Site.xlsm
in/hr
9.95
7.72
6.52
5.60
4.98
4.52
4.08
3.74
3.46
3.23
3.03
2.86
2.59
23S
2.21
2.06
1.94
1.84
tjs
0.5
0.4
03
03
03
0.2
0.2
0.2
02
0.2
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
155
241
305
349
388
423
445
466
485
503
519
535
565
593
620
642
665
688
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
DETENTION P�ND V�Ll1ME (FAA Methnd) � UNITED CIVIL
Apex-Haven Apartments, Fort Collins. C� Design Group
I�0 Year Storm Into Detention Facility
Areo = 48,047 squarefeet
Area = 1.10 acres
� iaa = 0.83
Release Rate Out of Pond
Q o�7 = o.ss �fs
Unit Flow = 0.77 cfs/acre
Notes:
1. Release Rate indudes 03 cfs from the The Slab property per the Northern Report plus 0.63 cfs from onsite, limiting the total site flows entering Prospect to the 100-year historic value.
2. Pond area indudes 0.49 acres from the The Slab property per [he Northern Report in addition to onsite Basins B1-63 and 51.
Oetention Volume Caleulations
Rainfall Rainfall Inflow Rate Inflow Volume Adjustment
Duration (T) Intensity (q Q,� FCloo*Area*I V,=(4;�*T*60) Factor
m= 0.5(1 + T�/T)
min
5
10
15
20
25
30
35
40
45
50
55
60
70
SO
90
100
110
120
Average
Outflow Rate
��= m��b��
cfs
0.43
0.85
0.85
0.85
O.SS
O.SS
O.SS
O.SS
0.85
O.SS
0.85
0.85
O.SS
O.SS
O.SS
O.SS
O.SS
0.85
Outflow Volume Required
Vo Qa�*T *60 Storage Volume
V� V, vo
128
510
765
1,020
1,275
1,530
1,785
2,040
2,295
2,550
2,805
3,060
3,570
4,080
4,590
5,100
5,610
2,616
3,747
4,628
5,157
5,591
5,948
6,090
6,210
6,292
6,356
6,385
6,403
6,428
6,420
6,379
6,260
6,159
Required Detention Volume
Vloo = 6,428 cubicfeet
�ioo = 0.15 acre-ft
Date: 12/9/2020 C:�United Civil Dropbox�Projects�U19031 - Haven Aportments�Reports�Droinoge�Colculotions�U19031-0roin Colcs-Revised Site.xlsm
in/hr
9.95
7.72
6.52
5.60
4.98
4.52
4.08
3.J4
3.46
3.23
3.03
2.86
2.59
238
2.21
2.06
1.94
1.84
cfs
9.1
7.1
6.0
5.1
4.6
4.2
3.8
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
1.9
1.8
1.7
2,744
4,257
5,393
6,177
6,866
7,478
7,875
8,250
8,587
8,906
9,190
9,463
9,998
10,500
10,969
11,360
11,769
0.50
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
DETENTI�N P�ND STORAGE AND ORIFICE CALCULATI�N3
Aoex-Haven Aoartments. Fart Callins. CO
f�„ UNITED CIVIL
� �� Desgn G�-oup
3tage 3torage Caleulations
Elevation Area (sf) Depth (ft) Volume (ef) Volume total (cf) ft)
?z.so s.00 o.00 0 0 0.00
?2.60 70937 0.10 55 55 0.00
22.70 1,178.55 0.10 93 93 0.00
?2.80 1,254.04 0.10 122 215 0.00
22.90 1,32615 0.10 129 344 0.01
?3.00 1,725.79 0.10 152 496 0.01
23.10 1,759.45 0.10 176 672 0.02
t3.20 1,835.59 0.10 181 853 0.02
t330 1,852.01 0.10 184 1,038 0.02
t3.40 1,86838 0.10 186 1,224 0.03
23.50 1,884.74 0.10 188 1,411 0.03
23.60 1,901.63 0.10 189 1,601 0.04
23.70 1,91936 0.10 191 1,792 0.04
t3.80 1,938.23 0.10 193 1,984 0.05
t3.90 1,957.46 0.10 195 2,179 0.05
?4.00 1,977.11 0.10 197 2,376 0.05
24.10 1,997.24 0.10 199 2,575 0.06
?4.20 2,017.83 0.10 201 2,775 0.06
2430 2,038.85 0.10 203 2,978 0.07
t4.40 2,060.28 0.10 205 3,183 0.07
24.50 2,OS2.03 0.10 207 3,390 0.08
t4.60 2,104.13 0.10 209 3,600 0.08
24.70 2,126.69 0.10 212 3,811 0.09
t4.80 2,149.76 0.10 214 4,025 0.09
t4.90 2,17335 0.10 216 4,241 0.10
t5.00 2,197.49 0.10 219 4,460 0.10
t5.10 2,222.14 0.10 221 4,651 0.11
25.20 2,247.18 0.10 223 4,904 0.11
2530 2,272.67 0.10 226 5,130 0.12
t5.40 2,298.81 0.10 229 5,359 0.12
25.50 2,325.61 0.10 231 5,590 0.13
?5.60 2,353.08 0.10 234 5,824 0.13
25.70 2,351.22 0.10 237 6,061 0.14
?5.80 2,409.99 0.10 240 6,300 0.14
25.90 2,439.51 0.10 242 6,543 0.15
t6.00 2,469.91 0.10 245 6,758 0.16
Uetention Pond Storage 6 Water Quality �rifiee Opening
100-Year Detention Volume and Elevations 100-Year Orifice Calculation
Detention Volume Required = 6,428 ft' Orifice Flow Rate, Q= CoAo�2gHo)°�s cfs
0.15 ac-ft Area of orifice Ao, kZ = Q
Elevai- Elevao (VolReq„�„ea Volga�+Elevgo Co(2gHo)os
W.S. Elevation, ft=
VolBi - VoBo Co = 0.65
Required W.S. Elevation = 5025.85 ft Q= 4 0,,, of pond = 0.85 cfs
Provided W.S. Elevation = 5026.00 ft gravitational acceleration g= 3L2 ft/secZ
Detention Volume Provided = 6,788 ft' diam = 0.337 ft
0.16 ao-ft Effective heod on orifice H o= D-1/2diom = 333 ft
100-year Depth D= 3.50 ft Area of orifice A o= 0.09 ft�
Top-of-Berm = 5026.50 ft Area of orifice A o= 12.56 ���
Freeboard= 0.50 ft 100-YearOrificeDiameter= 4.05 4 1/16 inches
Date: 4/21/2021 C:�United Civil Dropbox�Projeds�U19031 - Haven Apartments�Reports�Droinage�Calculations�U19031-Drain Calcs-Revised Site.xlsm
DETENTION P�ND V�Ll1ME (FAA Methnd) � UNITED CIVIL
Apex-Haven Apartments, Fort Collins. C� Design Group
I�0 Year Storm Into Detention Facility
Areo = 7,504 squarefeet
Area = 0.18 acres
�iaa = O.SS
Release Rate Out of Pond
Q o�7 = o.zs �fs
Unit Flow = 1.56 cfs/acre
Notes:
1. Pond area includes onsite Basins Cl and Q.
Oetention Volume Caleulations
Rainfall Rainfall Inflow Rate Inflow Volume Adjustment
Duration (T) Intensity (q Q,� FCloo*Area*I V,=(4;�*T*60) Factor
m= 0.5(1 + T�/T)
min
5
10
15
20
25
30
35
40
45
50
55
60
70
SO
90
100
110
120
Average
Outflow Rate
��= m��b��
cfs
0.14
0.28
028
0.28
018
0.25
0.28
01S
0.28
01S
0.25
0.25
0.25
0.25
0.28
01S
0.28
018
Outflow Volume Required
Vo Qa�*T *60 Storage Volume
V� V, vo
42
168
252
336
420
504
SSS
672
756
S40
924
1,008
1,176
1,344
1,512
1,680
1,848
428
562
673
723
757
778
762
742
716
687
651
614
538
456
368
267
169
71
Required Detention Volume
Vloo = 778 cubicfeet
�ioo = 0.02 acre-ft
Date: 12/9/2020 C:�United Civil Dropbox�Projects�U19031 - Haven Aportments�Reports�Droinoge�Colculotions�U19031-0roin Colcs-Revised Site.xlsm
in/hr
9.95
7.72
6.52
5.60
4.98
4.52
4.08
3.J4
3.46
3.23
3.03
2.86
2.59
238
2.21
2.06
1.94
1.84
cfs
1.6
1.2
1.0
0.9
0.8
OJ
0.6
0.6
0.5
0.5
0.5
0.5
0.4
0.4
03
03
0.3
03
470
730
925
1,059
1,177
1,282
1,350
1,414
1,472
1,527
1,575
1,622
1,714
1,800
1,880
1,947
2,017
0.50
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
DETENTI�N P�ND STORAGE AND ORIFICE CALCULATI�N3
Aoex-Haven Aoartments. Fart Callins. CO
j�„ UNITED CIVIL
� �� Desgn G�-oup
3tage 3torage Caleulations
Elevation Area (sf) Depth (ft) Volume (ef) Volume total (cf) ft)
?z.�o o.ao o.00 0 0 0.00
�z.ao si.�i o.io z 2 0.00
22.90 20032 0.10 12 14 0.00
t3.00 440.92 0.10 31 45 0.00
23.10 507.79 0.10 47 92 0.00
?3.20 516.15 0.10 51 144 0.00
23.30 524.55 0.10 52 196 0.00
t3.40 533.00 0.10 53 248 0.01
t3.50 541.50 0.10 54 302 0.01
t3.60 550.05 0.10 55 357 0.01
23.70 558.65 0.10 SS 412 0.01
23.80 56732 0.10 56 469 0.01
23.90 576.06 0.10 57 526 0.01
t4.00 584.88 0.10 58 584 0.01
t4.10 593.76 0.10 59 643 0.01
?4.20 602.72 0.10 60 702 0.02
2430 611.81 0.10 61 763 0.02
?4.40 621.04 0.10 62 825 0.02
24.50 630.44 0.10 63 887 0.02
t4.60 639.99 0.10 64 951 0.02
24.70 649.71 0.10 64 1,015 0.02
t4.80 659.59 0.10 65 1,081 0.02
Oetention Pund Storage S Water Quality �rifiee Opening
100-Year Detention Volume and Elevations 300-Year Orifice Calculation
Detention Volume Required = 778 ft' Orifice Flow Rate, Q= CoAo�2gHo)o.s cfs
0.02 ac-ft Area of orifice Ao, ftZ = Q
Elevai- Elevao (VolReq„�„ea Volga�+Elevga Co(2gHo)os
W.S. Elevation, ft=
Vo181 - VoBo Co = 0.65
Required W.S. Elevation = 5024.32 ft Q= 4 0,,, of pond = 0.28 cfs
Provided W.S. Elevation = 5024.80 ft gravitotional accelerotion g= 322 ft/secZ
Detention Volume Provided = 1,081 ft' diam = 0.220 ft
0.02 ao-ft Effective heod on orifice H o= D-1/2diom = 1.99 ft
100-year Depth D= 2.10 ft Areo of orifice A o= 0.04 ft�
Top-of-Berm = 5024.50 ft Area of orifice A o= 5.48 in�
Freeboard= O.00ft 100-YearOrificeDiameter= 2.64 2 5/8 inches
Date: 4/21/2021 C:�United Civil Dropbox�Projeds�U19031 - Haven Apartments�Reports�Droinage�Calculations�U19031-Drain Calcs-Revised Site.xlsm
IJNDERGRDIJND DETENTION � WATER QUALITY
Apez-Haven Gpartments. Fort Collins, C�
Cham6er
10
A (WQ/LID)
iotal Required Detention/ Chamber Chamber Unit Cham6er *Installed Min. Min.
Detention/INQ WIl Type Release Rate` llnit Cham6er llnit No. of IMl
M
Valumea Inflow6 Volumed Volume ine. Chambers� Release
Aggregatee Rate9
(ef) (efs) (efs) (cf) (ef) (ea) (efs)
195 0.42 SG310 0.016 14J0 31.00 7 0.11
Min. Req'd
Isolator Row
Volume 6y
FAA Methodh
(ef)
112
WQCV 8 0.13
*Volume assumes minimum aggregate depth below chamber.
a. Total required WQCV calculated per 12-hr drain time.
b. WQ inflow is approximated as one-half the 2-yr peak runoff rate.
c Release rate per chamber, limited by flow through geotextile with accumulated sediment.
d. Volume within chamber only, not accounting for void spaces in surrounding aggregate. The Isolator Row�s) are sized perthis unit volume.
e. Volume includes chamber and void spaces (40%) in surrounding aggregate, per chamber unit. The total system WQCV is sized perthis unit volume.
f. Number of chambers required to provide full WQCV within total installed system, including aggregate.
g. Release rate per chamber times number of chambers. This is used at the'outlet control' for the FAA calculations.
h. Minimum'chamber-only'volume to ensure dirty water is fully contained within Isolator Row.
i. Determines whether the design is controlled by the Isolator Row volume or WQCV.
j. Release rate per chamber times number of chambers provided. This is the approximate controlled discharge from the WQ event.
k. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume.
I. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required 12-hr WQCV.
m. Underground facility is designed to provide WQfor all "A" and "C" Basins
�esign No. nf Provided
Control' Cham6ers IM�
M
Provided Release
Rate'
(efs)
Date: 12/9/2020 C: �United Civil Dropbox�Projects�U19031 - Haven Aportments�Reports�Drain
DRAIN BASIN 3-2 Nyloplast 8" Dome Grate Inlet Capacity Chart
1.20
1.10
1.00
0.90
0.80
0.70
N
U
T 0.6�
U
N
C
N
V
0.50
0.40
Basin A2 0.30
Q100 - 0.20 cFs
0.20
0.10
0.00 �� , � . � � � � � � � � � � � � � � � � �
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05
Head (ft)
��
Nyloplast
3130 Verona Avenue • Buford, GA 30518
(866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490
0 Nyloplast Inlet Capacity Charts June 2012
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
Project:
InIetID:
Inlet 1-6
� T�
T. Ty�
�"'. Vi T.
r�.
� 4 - �7�tEET
�=r:��i
f " �_-
mum Allowable Width for Spread Behind Curb
Slope Behind Curb (leave blank for no conveyance credit behind curb)
iing's Roughness Behind Curb (typically between 0.012 and 0.020)
of Curb at Gutter Flow Line
ce from Curb Face to Street Crown
W idth
Transverse Slope
Cross Slope (typically 2 inches over 24 inches or 0.083 fUft)
Longitudinal Slope - Enter 0 for sump condition
ig's Roughness for Street Section (typically between 0.012 and OA20)
TencK = 0.5 ft
SencK = 0.020 Poft
�encK = 0.013
Hwae = 6.00 inches
TcaowN = 24.0 ft
W = 1.00 ft
Sx = 0.020 Poft
Sw = 0.083 ftlft
So = 0.055 Poft
�s1aEEr = 0.013
Allowable Spread for Minor 6 Major Storm
Allowable Depth at Gutter Flowline for Minor 8 Major Storm
Flow Depth at Street Crown (leave blank for no)
Minor Storm Major Storm
Tmnx = 10.0 10D ft
dmnx = 6.0 6.0 inches
_i � check = yes
INOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm
AJOR STORM Allowable Capacity is based on Spread Criterion �,now = 7.4 7.4 cfs
inor storm max. allowable capacity GOOD - greater [han the design flow given on sheet'Inlet ManagemenY
aior storm max. allowable caoaci[v GOOD - qreater than the desion flow qiven on sheet'Inlet Manaaement'
UD-Inlet v4.06.xlsm, Inlet 1-6 4/21/2021, 828 PM
INLET ON A CONTINUOUS GRADE
Version 4.06 Released August 2018
�Lo (C)�
H-Curb H-Vert
Wo
W
�
.. Lo fG!
of Inlet
I CDOTType R Curb Opening
Depression (additional to continuous gutter depression'a')
Number of Units in the Inlet (Grate or Curb Opening)
h of a Single Unit Inlet (Grate or Curb Opening)
i of a Unit Grate (cannot be qreater than W, Gutter W idth)
3ing Factor for a Single Unit Grate (typical min, value = 0.5)
ainq Factor for a Sinqle Unit Curb Openinq (Npical min. value = 0.
Inlet Interception Capacity
Inlet Carry-Over Flow (fiow bypassing inlet)
�.a va.�a�fa�a = n_in_ _
Type
a�ocn�
No
Lo
Wo
CrG
Q
Qe
C%
MINOR MAJOR
CDOT Type R Curb Openini
3.0
1
5.00
NIA
NIA NIA
0.10 0.10
MINOR MAJOR
0.0 0.2
0.0 0.0
100 100
UD-Inlet v4.06.xlsm, Inlet 1-6 4/21/2021, 828 PM
Hydraflow Storm Sewers Extension for Autodesk0 Civil 3D0 Plan
,�� 22 20 18 17
uutran
Project File: Storm Drain - East.stm � Number of lines: 36
Storm Sewer Inventory Report
Line Alignment Flow Data Physical Data
No.
Dnstr Line Defl Junc Known Drng Runoff Inlet Invert Line Invert Line Line N J-Lo
Line Length angle Type Q Area Coeff Time EI Dn Slope EI Up Size Shape Value Coei
No. (ft) (deg) (cfs) (ac) (C) (min) (ft) (°/a) (ft) (in) (n) (K)
1 End 31.572 -87.585 MH 1.52 0.00 0.00 0.0 5020.24 0.25 5020.32 8 Cir 0.012 1.0
2 1 4.417 -1.733 MH 0.48 0.00 0.00 0.0 5020.32 0.23 5020.33 8 Cir 0.012 0.1
3 2 3.333 -0.049 MH 0.48 0.00 0.00 0.0 5020.33 0.29 5020.34 8 Cir 0.012 0.1
4 3 3.333 0.001 None 0.48 0.00 0.00 0.0 5020.34 0.31 5020.35 8 Cir 0.012 1.0
5 4 6.389 0.001 None 0.28 0.00 0.00 0.0 5020.35 0.15 5020.36 8 Cir 0.012 0.�
6 5 10.182 -23.133 None 0.28 0.00 0.00 0.0 5020.36 0.30 5020.39 8 Cir 0.012 0.�
7 6 26.730 23.133 None 0.28 0.00 0.00 0.0 5020.39 0.26 5020.46 8 Cir 0.012 O.E
8 7 9.695 -26.379 Grate 0.28 0.00 0.00 0.0 5020.46 0.21 5020.48 8 Cir 0.012 0. i
9 8 18.808 25.763 None 1.35 0.00 0.00 0.0 5020.73 0.48 5020.82 8 Cir 0.012 1.0
10 9 4.220 0.009 None 1.20 0.00 0.00 0.0 5020.82 0.47 5020.84 8 Cir 0.012 0.�
11 10 8.009 11.243 None 1.20 0.00 0.00 0.0 5020.84 0.50 5020.88 8 Cir 0.012 0.�
12 11 5.602 -11.250 None 1.20 0.00 0.00 0.0 5020.88 0.54 5020.91 8 Cir 0.012 1.0
13 12 52.522 0.000 None 1.05 0.00 0.00 0.0 5020.91 0.49 5021.17 8 Cir 0.012 1.0
14 13 13.103 0.000 None 0.90 0.00 0.00 0.0 5021.17 0.54 5021.24 8 Cir 0.012 1.0
15 14 41.313 0.000 None 0.75 0.00 0.00 0.0 5021.24 0.51 5021.45 8 Cir 0.012 1.0
16 15 6.868 0.000 None 0.60 0.00 0.00 0.0 5021.45 0.58 5021.49 8 Cir 0.012 1.0
17 16 31.995 -89.744 None 0.60 0.00 0.00 0.0 5021.56 0.50 5021.72 8 Cir 0.012 1.0
18 17 46.506 0.000 None 0.45 0.00 0.00 0.0 5021.72 0.52 5021.96 8 Cir 0.012 1.0
19 18 7.855 -90.256 None 0.15 0.00 0.00 0.0 5022.03 5.10 5022.43 6 Cir 0.012 1.0
20 18 2.083 0.000 None 0.30 0.00 0.00 0.0 5021.96 0.49 5021.97 8 Cir 0.012 1.0
21 20 5.514 -90.256 None 0.15 0.00 0.00 0.0 5022.05 5.08 5022.33 6 Cir 0.012 1.0
22 20 41.070 0.000 None 0.15 0.00 0.00 0.0 5021.97 0.49 5022.17 8 Cir 0.012 0.7
23 22 6.642 -45.256 None 0.15 0.00 0.00 0.0 5022.17 0.46 5022.20 8 Cir 0.012 1.0
Project File: Storm Drain - East.stm Number of lines: 36
Storm Sewer Inventory Report
Line Alignment Flow Data Physical Data
No.
Dnstr Line Defl Junc Known Drng Runoff Inlet Invert Line Invert Line Line N J-Lo
Line Length angle Type Q Area Coeff Time EI Dn Slope EI Up Size Shape Value Coei
No. (ft) (deg) (cfs) (ac) (C) (min) (ft) (°/a) (ft) (in) (n) (K)
24 17 5.485 -90.256 None 0.15 0.00 0.00 0.0 5021.80 5.11 5022.08 6 Cir 0.012 1.0
25 15 5.588 -90.000 None 0.15 0.00 0.00 0.0 5021.52 5.01 5021.80 6 Cir 0.012 1.0
26 14 5.588 -90.000 None 0.15 0.00 0.00 0.0 5021.32 5.02 5021.60 6 Cir 0.012 1.0
27 13 5.935 -90.000 None 0.15 0.00 0.00 0.0 5021.25 5.05 5021.55 6 Cir 0.012 1.0
28 12 5.938 -90.000 None 0.15 0.00 0.00 0.0 5020.99 5.05 5021.29 6 Cir 0.012 1.0
29 9 5.483 -90.017 None 0.15 0.00 0.00 0.0 5020.90 5.11 5021.18 6 Cir 0.012 1.0
30 1 27.389 -91.733 MH 1.04 0.00 0.00 0.0 5020.32 0.22 5020.38 8 Cir 0.012 1.0
31 30 7.726 89.474 MH 1.04 0.00 0.00 0.0 5020.38 0.13 5020.39 8 Cir 0.012 O.f
32 31 13.035 -50.806 MH 1.04 0.00 0.00 0.0 5020.39 0.23 5020.42 8 Cir 0.012 O.E
33 32 45.678 -53.683 Curb 1.04 0.00 0.00 0.0 5020.42 0.26 5020.54 8 Cir 0.012 0.°
34 33 40.459 6.432 Grate 0.85 0.00 0.00 0.0 5020.54 0.25 5020.64 8 Cir 0.012 1.0
35 4 20.337 -90.004 MH 0.20 0.00 0.00 0.0 5020.35 0.20 5020.39 8 Cir 0.012 O.E
36 35 13.960 34.485 Grate 0.20 0.00 0.00 0.0 5020.39 0.21 5020.42 8 Cir 0.012 1.0
Project File: Storm Drain - East.stm Number of lines: 36
Storm Sewer Summary Report
Line Line ID Flow Line Line Line Invert Invert Line HGL HGL Minor
No. rate Size shape length EL Dn EL Up Slope Down Up loss
(cfs) (in) (ft) (ft) (ft) (°/a) (ft) (ft) (ft)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
PIPE 1
PIPE 7
PIPE 8
PIPE 9
PIPE 10
PIPE 11
PIPE 12
PIPE 13
PIPE 14
PIPE 15
PIPE 16
PIPE 17
PIPE 18
PIPE 19
PIPE 20
PIPE 21
PIPE 23
PIPE 24
PIPE 24-1
PIPE 25
PIPE 25-1
PIPE 26
PIPE 27
PIPE 23-1
Project File: Storm Drain - East.stm
1.52
0.48
0.48
0.48
0.28
0.28
0.28
0.28
1.35
1.20
1.20
1.20
1.05
0.90
0.75
0.60
0.60
0.45
0.15
0.30
0.15
0.15
0.15
0.15
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
6
8
6
8
8
6
NOTES: Return period = 100 Yrs. ;*Surcharged (HGL above crown).
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
31.572 5020.24
4.417 5020.32
3.333 5020.33
3.333 5020.34
6.389 5020.35
10.182 5020.36
26.730 5020.39
9.695 5020.46
18.808 5020.73
4.220 5020.82
8.009 5020.84
5.602 5020.88
52.522 5020.91
13.103 5021.17
41.313 5021.24
6.868 5021.45
31.995 5021.56
46.506 5021.72
7.855 5022.03
2.083 5021.96
5.514 5022.05
41.070 5021.97
6.642 5022.17
5.485 5021.80
5020.32
5020.33
5020.34
5020.35
5020.36
5020.39
5020.46
5020.48
5020.82
5020.84
5020.88
5020.91
5021.17
5021.24
5021.45
5021.49
5021.72
5021.96
5022.43
5021.97
5022.33
5022.17
5022.20
5022.08
0.252
0.232
0.293
0.308
0.153
0.297
0.261
0.206
0.478
0.474
0.500
0.540
0.495
0.537
0.508
0.583
0.501
0.516
5.098
0.492
5.083
0.486
0.456
5.110
5020.82` 5021.28� 0.29
5021.58" 5021.58� 0.00
5021.59' 5021.59� 0.00
5021.59' 5021.60� 0.03
5021.63" 5021.63� 0.00
5021.64'` 5021.64� 0.00
5021.65* 5021.66' 0.01
5021.66` 5021.67� 0.01
5021.67'' S021.87' 0.23
5022.11` 5022.14' 0.04
5022.18' S022.25' 0.04
5022.29' 5022.34� 0.18
5022.53' 5022.86� 0.14
5023.00" 5023.07' 0.10
5023.17` 5023.31� 0.07
5023.38* 5023.39' 0.05
5023.44` 5023.51 � 0.05
5023.55" 5023.61' 0.03
5023.63` 5023.64' 0.01
5023.63' S023.63' 0.01
5023.65* 5023.65� 0.01
5023.65' 5023.65� 0.00
5023.65' S023.65� 0.00
5023.55` 5023.55� 0.01
Number of lines: 36
Storm Sewer Summary Report
Line Line ID Flow Line Line Line Invert Invert Line
No. rate Size shape length EL Dn EL Up Slope
(cfs) (in) (ft) (ft) (ft) (°/a)
25 PIPE 20-1 0.15 6 Cir 5.588 5021.52 5021.80 5.007
26 PIPE 19-1 0.15 6 Cir 5.588 5021.32 5021.60 5.016
27 PIPE 18-1 0.15 6 Cir 5.935 5021.25 5021.55 5.051
28 PIPE 17-1 0.15 6 Cir 5.938 5020.99 5021.29 5.049
29 PIPE 14-1 0.15 6 Cir 5.483 5020.90 5021.18 5.111
30 PIPE 2 1.04 8 Cir 27.389 5020.32 5020.38 0.219
31 PIPE 3 1.04 8 Cir 7.726 5020.38 5020.39 0.133
32 PIPE 4 1.04 8 Cir 13.035 5020.39 5020.42 0.229
33 PIPE 5 1.04 8 Cir 45.678 5020.42 5020.54 0.263
34 PIPE 6 0.85 8 Cir 40.459 5020.54 5020.64 0.247
35 PIPE 9-1 0.20 8 Cir 20.337 5020.35 5020.39 0.197
36 PIPE 9-2 0.20 8 Cir 13.960 5020.39 5020.42 0.213
Project File: Storm Drain - East.stm
NOTES: Return period = 100 Yrs. ;*Surcharged (HGL above crown).
HGL HGL Minor
Down Up loss
(ft) (ft) (ft)
5023.38` 5023.38� 0.01
5023.17" 5023.17� 0.01
5023.00* 5023.01� 0.01
5022.53' 5022.53� 0.01
5022.11 " 5022.11 � 0.01
5021.58'` 5021.75� 0.14
5021.89* 5021.94' 0.11
5022.05` 5022.13� 0.12
5022.25" 5022.53* 0.07
5022.60� 5022.77' 0.09
5021.63' S021.63' 0.00
5021.64* 5021.64� 0.01
Number of lines: 36
Hydraulic Grade Line Computations
Line Size Q Downstream
Invert HGL Depth Area Vel Vel EGL
elev elev head elev
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
6
8
6
8
1.52 5020.24 5020.82 0.58 0.32 4.75
0.48 5020.32 5021.58 0.67 0.35 1.38
0.48 5020.33 5021.59 0.67 0.35 1.38
0.48 5020.34 5021.59 0.67 0.35 1.38
0.28 5020.35 5021.63 0.67 0.35 0.80
0.28 5020.36 5021.64 0.67 0.35 0.80
0.28 5020.39 5021.65 0.67 0.35 0.80
0.28 5020.46 5021.66 0.67 0.35 0.80
1.35 5020.73 5021.67 0.67 0.35 3.87
1.20 5020.82 5022.11 0.67 0.35 3.44
1.20 5020.84 5022.18 0.67 0.35 3.44
1.20 5020.88 5022.29 0.67 0.35 3.44
1.05 5020.91 5022.53 0.67 0.35 3.01
0.90 5021.17 5023.00 0.67 0.35 2.58
0.75 5021.24 5023.17 0.67 0.35 2.15
0.60 5021.45 5023.38 0.67 0.35 1.72
0.60 5021.56 5023.44 0.67 0.35 1.72
0.45 5021.72 5023.55 0.67 0.35 1.29
0.15 5022.03 5023.63 0.50 0.20 0.76
0.30 5021.96 5023.63 0.67 0.35 0.86
0.15 5022.05 5023.65 0.50 0.20 0.76
0.15 5021.97 5023.65 0.67 0.35 0.43
Project File: Storm Drain - East.stm
0.35
0.03
0.03
0.03
0.01
0.01
0.01
0.01
0.23
0.18
0.18
0.18
0.14
0.10
0.07
0.05
0.05
0.03
0.01
0.01
0.01
0.00
Len
Invert
elev
) (ft) (ft)
Upstream
HGL Depth Area Vel Vel
elev head
(ft) (ft) (sqft) (ft/s) (ft)
5021.17 1.244 31.572 5020.32 5021.28 0.67 0.35 4.35 0.29
5021.60 0.135 4.417 5020.33 5021.58 0.67 0.35 1.38 0.03
5021.62 0.135 3.333 5020.34 5021.59 0.67 0.35 1.38 0.03
5021.62 0.135 3.333 5020.35 5021.60 0.67 0.35 1.38 0.03
5021.64 0.046 6.389 5020.36 5021.63 0.67 0.35 0.80 0.01
5021.65 0.046 10.182 5020.39 5021.64 0.67 0.35 0.80 0.01
5021.65 0.046 26.730 5020.46 5021.66 0.67 0.35 0.80 0.01
5021.67 0.046 9.695 5020.48 5021.67 0.67 0.35 0.80 0.01
5021.91 1.065 18.808 5020.82 5021.87 0.67 0.35 3.87 0.23
5022.29 0.842 4.220 5020.84 5022.14 0.67 0.35 3.44 0.18
5022.37 0.842 8.009 5020.88 5022.25 0.67 0.35 3.44 0.18
5022.48 0.842 5.602 5020.91 5022.34 0.67 0.35 3.44 0.18
5022.67 0.644 52.522 5021.17 5022.86 0.67 0.35 3.01 0.14
5023.11 0.473 13.103 5021.24 5023.07 0.67 0.35 2.58 0.10
5023.24 0.329 41.313 5021.45 5023.31 0.67 0.35 2.15 0.07
5023.42 0.210 6.868 5021.49 5023.39 0.67 0.35 1.72 0.05
5023.48 0.210 31.995 5021.72 5023.51 0.67 0.35 1.72 0.05
5023.58 0.118 46.506 5021.96 5023.61 0.67 0.35 1.29 0.03
5023.64 0.061 7.855 5022.43 5023.64 0.50 0.20 0.76 0.01
5023.64 0.053 2.083 5021.97 5023.63 0.67 0.35 0.86 0.01
5023.65 0.061 5.514 5022.33 5023.65 0.50 0.20 0.76 0.01
5023.65 0.013 41.070 5022.17 5023.65 0.67 0.35 0.43 0.00
Number of lines: 36
; c= cir e= ellip b= box
Hydraulic Grade Line Computations
Line Size Q Downstream
Invert HGL Depth Area Vel Vel EGL
elev elev head elev
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft)
23
24
25
26
27
28
29
30
31
32
33
34
35
36
8
6
6
6
6
6
6
8
8
8
8
8
8
8
0.15 5022.17 5023.65 0.67 0.35 0.43
0.15 5021.80 5023.55 0.50 0.20 0.76
0.15 5021.52 5023.38 0.50 0.20 0.76
0.15 5021.32 5023.17 0.50 0.20 0.76
0.15 5021.25 5023.00 0.50 0.20 0.76
0.15 5020.99 5022.53 0.50 0.20 0.76
0.15 5020.90 5022.11 0.50 0.20 0.76
1.04 5020.32 5021.58 0.67 0.35 2.98
1.04 5020.38 5021.89 0.67 0.35 2.98
1.04 5020.39 5022.05 0.67 0.35 2.98
1.04 5020.42 5022.25 0.67 0.35 2.98
0.85 5020.54 5022.60 0.67 0.35 2.44
0.20 5020.35 5021.63 0.67 0.35 0.57
0.20 5020.39 5021.64 0.67 0.35 0.57
Project File: Storm Drain - East.stm
0.00
0.01
0.01
0.01
0.01
0.01
0.01
0.14
0.14
0.14
0.14
0.09
0.01
0.01
Len
Invert
elev
) (ft) (ft)
Upstream
HGL Depth Area Vel Vel
elev head
(ft) (ft) (sqft) (ft/s) (ft)
5023.66 0.013 6.642 5022.20 5023.65 0.67 0.35 0.43 0.00
5023.56 0.061 5.485 5022.08 5023.55 0.50 0.20 0.76 0.01
5023.39 0.061 5.588 5021.80 5023.38 0.50 0.20 0.76 0.01
5023.18 0.061 5.588 5021.60 5023.17 0.50 0.20 0.76 0.01
5023.01 0.061 5.935 5021.55 5023.01 0.50 0.20 0.76 0.01
5022.53 0.061 5.938 5021.29 5022.53 0.50 0.20 0.76 0.01
5022.12 0.061 5.483 5021.18 5022.11 0.50 0.20 0.76 0.01
5021.71 0.632 27.389 5020.38 5021.75 0.67 0.35 2.98 0.14
5022.02 0.632 7.726 5020.39 5021.94 0.67 0.35 2.98 0.14
5022.19 0.632 13.035 5020.42 5022.13 0.67 0.35 2.98 0.14
5022.38 0.632 45.678 5020.54 5022.53 0.67 0.35 2.98 0.14
5022.70 0.422 40.459 5020.64 5022.77 0.67 0.35 2.44 0.09
5021.63 0.023 20.337 5020.39 5021.63 0.67 0.35 0.57 0.01
5021.64 0.023 13.960 5020.42 5021.64 0.67 0.35 0.57 0.01
Number of lines: 36
; c= cir e= ellip b= box
Storm Sewer Profile
Elev. (ft)
5033.00
5030.00
5027.00
5024.00
5021.00
5018.00
HGL EGL
0 25 50 75 100 125 150 175
Storm Sewer Profile
f6
� �j C
Q M �
N �
O;� Q
o =v
Elev. (ft) a �; w�
t
p -b '�'
� i ?
U} U� —
1.31$IiI1I1
5030.00
5027.00
5024.00
5021.00
5018.00 �
0
25
HGL
O N
� M M M
� 7 7 �
C Q C C Q C C O C C O C
J NNN J�OOP� J MO?m J�NN
�'.MM �MM �MM N�V
� `-�00 (p MOO � MOO N �00
�`;'NN � NNN Cp NNN I� NNN
�oo �oo �oo �oo
�r� ,n u.y � �. �i �ri � � �n �n m 'n �n �n
p'�-'�W O W W W O W W W O W W W
� � 3 > � � > > � � > > � � > >
� �= cc � �cc � �cc � �cc
EGL
50
M
M
7
J � �
r <7' <i'
� `-�. � ..^.
� QOO
cc� �NN
c� �
N � �f? �f�
'r iil i�i �
y � 7 �
� jycc
45.678L - 8" 0.26% 4n.n5y�t - a�� r
- o
0
_ o
75 100 125 150
Reach (ft)
Hydraflow Storm Sewers Extension for Autodesk0 Civil 3D0 Plan
14 12 10
13�
16
Out
Project File: Roof Drain - East.stm � Number of lines: 21
Storm Sewer Inventory Report
Line Alignment Flow Data Physical Data
No.
Dnstr Line Defl Junc Known Drng Runoff Inlet Invert Line Invert Line Line N J-Lo
Line Length angle Type Q Area Coeff Time EI Dn Slope EI Up Size Shape Value Coei
No. (ft) (deg) (cfs) (ac) (C) (min) (ft) (°/a) (ft) (in) (n) (K)
1 End 18.808 -89.982 None 1.35 0.00 0.00 0.0 5020.73 0.48 5020.82 8 Cir 0.012 1.0
2 1 4.220 0.009 None 1.20 0.00 0.00 0.0 5020.82 0.47 5020.84 8 Cir 0.012 0.�
3 2 8.009 11.243 None 1.20 0.00 0.00 0.0 5020.84 0.50 5020.88 8 Cir 0.012 0.�
4 3 5.602 -11.250 None 1.20 0.00 0.00 0.0 5020.88 0.54 5020.91 8 Cir 0.012 1.0
5 4 52.522 0.000 None 1.05 0.00 0.00 0.0 5020.91 0.49 5021.17 8 Cir 0.012 1.0
6 5 13.103 0.000 None 0.90 0.00 0.00 0.0 5021.17 0.54 5021.24 8 Cir 0.012 1.0
7 6 41.313 0.000 None 0.75 0.00 0.00 0.0 5021.24 0.51 5021.45 8 Cir 0.012 1.0
8 7 6.868 0.000 None 0.60 0.00 0.00 0.0 5021.45 0.50 5021.49 8 Cir 0.012 1.0
9 8 31.995 -89.744 None 0.60 0.00 0.00 0.0 5021.56 0.50 5021.72 8 Cir 0.012 1.0
10 9 46.506 0.000 None 0.45 0.00 0.00 0.0 5021.72 0.52 5021.96 8 Cir 0.012 1.0
11 10 7.855 -90.256 None 0.15 0.00 0.00 0.0 5022.03 5.10 5022.43 6 Cir 0.012 1.0
12 10 2.083 0.000 None 0.30 0.00 0.00 0.0 5021.96 0.49 5021.97 8 Cir 0.012 1.0
13 12 5.514 -90.256 None 0.15 0.00 0.00 0.0 5022.05 5.08 5022.33 6 Cir 0.012 1.0
14 12 41.070 0.000 None 0.15 0.00 0.00 0.0 5021.97 0.49 5022.17 8 Cir 0.012 0.7
15 14 6.642 -45.256 None 0.15 0.00 0.00 0.0 5022.17 0.46 5022.20 8 Cir 0.012 1.0
16 9 5.485 -90.256 None 0.15 0.00 0.00 0.0 5021.80 5.11 5022.08 6 Cir 0.012 1.0
17 7 5.588 -90.000 None 0.15 0.00 0.00 0.0 5021.52 5.01 5021.80 6 Cir 0.012 1.0
18 6 5.588 -90.000 None 0.15 0.00 0.00 0.0 5021.32 5.02 5021.60 6 Cir 0.012 1.0
19 5 5.935 -90.000 None 0.15 0.00 0.00 0.0 5021.25 5.05 5021.55 6 Cir 0.012 1.0
20 4 5.938 -90.000 None 0.15 0.00 0.00 0.0 5020.99 5.05 5021.29 6 Cir 0.012 1.0
21 1 5.483 -90.017 None 0.15 0.00 0.00 0.0 5020.90 5.11 5021.18 6 Cir 0.012 1.0
Project File: Roof Drain - East.stm Number of lines: 21
Storm Sewer Summary Report
Line Line ID Flow Line Line Line Invert Invert Line HGL HGL Minor
No. rate Size shape length EL Dn EL Up Slope Down Up loss
(cfs) (in) (ft) (ft) (ft) (°/a) (ft) (ft) (ft)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
PIPE 14
PIPE 15
PIPE 16
PIPE 17
PIPE 18
PIPE 19
PIPE 20
PIPE 21
PIPE 23
PIPE 24
PIPE 24-1
PIPE 25
PIPE 25-1
PIPE 26
PIPE 27
PIPE 23-1
PIPE 20-1
PIPE 19-1
PIPE 18-1
PIPE 17-1
PIPE 14-1
Project File: Roof Drain - East.stm
1.35
1.20
1.20
1.20
1.05
0.90
0.75
0.60
0.60
0.45
0.15
0.30
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
8
8
8
8
8
8
8
8
8
8
6
8
6
8
8
6
6
6
6
6
6
NOTES: Return period = 100 Yrs. ;*Surcharged (HGL above crown).
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
18.808 5020.73
4.220 5020.82
8.009 5020.84
5.602 5020.88
52.522 5020.91
13.103 5021.17
41.313 5021.24
6.868 5021.45
31.995 5021.56
46.506 5021.72
7.855 5022.03
2.083 5021.96
5.514 5022.05
41.070 5021.97
6.642 5022.17
5.485 5021.80
5.588 5021.52
5.588 5021.32
5.935 5021.25
5.938 5020.99
5.483 5020.90
5020.82
5020.84
5020.88
5020.91
5021.17
5021.24
5021.45
5021.49
5021.72
5021.96
5022.43
5021.97
5022.33
5022.17
5022.20
5022.08
5021.80
5021.60
5021.55
5021.29
5021.18
0.478
0.474
0.500
0.540
0.495
0.537
0.508
0.505
0.501
0.516
5.098
0.492
5.083
0.486
0.456
5.110
5.007
5.016
5.051
5.049
5.111
5024.80` 5025.00� 0.23
5025.23" 5025.27� 0.04
5025.31* 5025.38� 0.04
5025.42' 5025.47� 0.18
5025.65" 5025.99� 0.14
5026.13'` 5026.19� 0.10
5026.30* 5026.43' 0.07
5026.50` 5026.52� 0.05
5026.56� 5026.63' 0.05
5026.68� 5026.73' 0.03
5026.76' S026.76' 0.01
5026.76` 5026.76� 0.01
5026.77* 5026.77� 0.01
5026.77" 5026.78' 0.00
5026.78` 5026.78� 0.00
5026.68* 5026.68" 0.01
5026.50` 5026.51� 0.01
5026.30" 5026.30' 0.01
5026.13` 5026.13' 0.01
5025.65' S025.66' 0.01
5025.23* 5025.24* 0.01
Number of lines: 21
Hydraulic Grade Line Computations
Line Size Q Downstream
Invert HGL Depth Area Vel Vel EGL
elev elev head elev
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
8
8
8
8
8
8
8
8
8
8
6
8
6
8
8
6
6
6
6
6
6
1.35 5020.73 5024.80 0.67 0.35 3.87
1.20 5020.82 5025.23 0.67 0.35 3.44
1.20 5020.84 5025.31 0.67 0.35 3.44
1.20 5020.88 5025.42 0.67 0.35 3.44
1.05 5020.91 5025.65 0.67 0.35 3.01
0.90 5021.17 5026.13 0.67 0.35 2.58
0.75 5021.24 5026.30 0.67 0.35 2.15
0.60 5021.45 5026.50 0.67 0.35 1.72
0.60 5021.56 5026.56 0.67 0.35 1.72
0.45 5021.72 5026.68 0.67 0.35 1.29
0.15 5022.03 5026.76 0.50 0.20 0.76
0.30 5021.96 5026.76 0.67 0.35 0.86
0.15 5022.05 5026.77 0.50 0.20 0.76
0.15 5021.97 5026.77 0.67 0.35 0.43
0.15 5022.17 5026.78 0.67 0.35 0.43
0.15 5021.80 5026.68 0.50 0.20 0.76
0.15 5021.52 5026.50 0.50 0.20 0.76
0.15 5021.32 5026.30 0.50 0.20 0.76
0.15 5021.25 5026.13 0.50 0.20 0.76
0.15 5020.99 5025.65 0.50 0.20 0.76
0.15 5020.90 5025.23 0.50 0.20 0.76
Project File: Roof Drain - East.stm
0.23
0.18
0.18
0.18
0.14
0.10
0.07
0.05
0.05
0.03
0.01
0.01
0.01
0.00
0.00
0.01
0.01
0.01
0.01
0.01
0.01
Len
Invert
elev
) (ft) (ft)
Upstream
HGL Depth Area Vel Vel
elev head
(ft) (ft) (sqft) (ft/s) (ft)
5025.03 1.065 18.808 5020.82 5025.00 0.67 0.35 3.87 0.23
5025.42 0.842 4.220 5020.84 5025.27 0.67 0.35 3.44 0.18
5025.49 0.842 8.009 5020.88 5025.38 0.67 0.35 3.44 0.18
5025.60 0.842 5.602 5020.91 5025.47 0.67 0.35 3.44 0.18
5025.79 0.644 52.522 5021.17 5025.99 0.67 0.35 3.01 0.14
5026.23 0.473 13.103 5021.24 5026.19 0.67 0.35 2.58 0.10
5026.37 0.329 41.313 5021.45 5026.43 0.67 0.35 2.15 0.07
5026.55 0.210 6.868 5021.49 5026.52 0.67 0.35 1.72 0.05
5026.61 0.210 31.995 5021.72 5026.63 0.67 0.35 1.72 0.05
5026.70 0.118 46.506 5021.96 5026.73 0.67 0.35 1.29 0.03
5026.77 0.061 7.855 5022.43 5026.76 0.50 0.20 0.76 0.01
5026.77 0.053 2.083 5021.97 5026.76 0.67 0.35 0.86 0.01
5026.78 0.061 5.514 5022.33 5026.77 0.50 0.20 0.76 0.01
5026.77 0.013 41.070 5022.17 5026.78 0.67 0.35 0.43 0.00
5026.78 0.013 6.642 5022.20 5026.78 0.67 0.35 0.43 0.00
5026.69 0.061 5.485 5022.08 5026.68 0.50 0.20 0.76 0.01
5026.51 0.061 5.588 5021.80 5026.51 0.50 0.20 0.76 0.01
5026.31 0.061 5.588 5021.60 5026.30 0.50 0.20 0.76 0.01
5026.14 0.061 5.935 5021.55 5026.13 0.50 0.20 0.76 0.01
5025.66 0.061 5.938 5021.29 5025.66 0.50 0.20 0.76 0.01
5025.24 0.061 5.483 5021.18 5025.24 0.50 0.20 0.76 0.01
Number of lines: 21
; c= cir e= ellip b= box
Storm Sewer Profile
This profile represents the storm sewer system
upstream of Pond C in the 100-year event.
@ r N M V tn CO
3 7 7 � � 7
�� c J�� � J o0 c J o� c J�0 c J Np c J�� C
O � M i N N i � V � 06 oa � � � � t� I� i V 7
N I� � NNW � NWpJ � NWCO � N�� N�� �, NNN
Elev. (ft) � 9� O p00 N 000 M OOQ M 000 (p O�� � O�r
O tf� N ap �NN O tnNN O�NN Cp �NN �NN N�NN
O � O O O O � O O O O ' O O ' O O
O — � � ��tn M ��� P ��� � ��fJtn � �tC)� N ���
� u.i W. �`1 W M W. �''� W � W, o W
o y w o-�ww o-�ww o-aww o-aww o-aww �-aww
w�> � E» � E» � E» � E>> � E» � �»
c/?�? � (/� U` cc � �cc � �cc � �c� � Ur cc � �cc
5033.00
5030.00
5027.00
Starting HGL Elevation
equals the maximum
Pond C ponding
elevation (5024.80).
5024.00
Pond C outlet
structure location. —'
5021.00
5018.00 �
0
2.522Lf - 8" (a> u.4 r�
- o
- o
- o
- 0.4 0
25 50 75
HGL EGL
100 125
r
7
� �O �
J
O��
r' NV V
� O��
� �00
7 uJ �t� �
+ -oww
� � »
� �jcc
Re
Hydraflow Storm Sewers Extension for Autodesk0 Civil 3D0 Plan
2$
vuttau
Project File: Storm Drain - West.stm � Number of lines: 31
Storm Sewer Inventory Report
Line Alignment Flow Data Physical Data
No.
Dnstr Line Defl Junc Known Drng Runoff Inlet Invert Line Invert Line Line N J-Lo
Line Length angle Type Q Area Coeff Time EI Dn Slope EI Up Size Shape Value Coei
No. (ft) (deg) (cfs) (ac) (C) (min) (ft) (°/a) (ft) (in) (n) (K)
1 End 14.905 -67.500 None 0.00 0.00 0.00 0.0 5022.68 0.47 5022.75 8 Cir 0.012 0.7
2 1 7.063 45.000 None 0.00 0.00 0.00 0.0 5022.75 0.57 5022.79 8 Cir 0.012 0.�
3 2 28.803 22.500 None 0.00 0.00 0.00 0.0 5022.79 0.49 5022.93 8 Cir 0.012 1.0
4 3 28.064 -90.000 None 0.00 0.00 0.00 0.0 5022.93 0.50 5023.07 8 Cir 0.012 1.0
5 4 60.555 0.000 MH 0.00 0.00 0.00 0.0 5023.07 0.51 5023.38 8 Cir 0.012 1.0
6 5 13.690 90.000 None 0.00 0.00 0.00 0.0 5023.58 0.95 5023.71 8 Cir 0.012 1.0
7 6 10.647 0.000 None 0.00 0.00 0.00 0.0 5023.71 1.03 5023.82 8 Cir 0.012 1.0
8 7 9.992 -90.000 None 0.00 0.00 0.00 0.0 5023.82 1.00 5023.92 8 Cir 0.012 1.0
9 8 13.097 0.000 None 0.00 0.00 0.00 0.0 5023.92 0.99 5024.05 8 Cir 0.012 1.0
10 9 11.820 0.000 None 0.00 0.00 0.00 0.0 5024.05 1.02 5024.17 8 Cir 0.012 1.0
11 10 9.253 90.000 None 0.11 0.00 0.00 0.0 5024.25 5.08 5024.72 6 Cir 0.012 1.0
12 4 35.089 90.000 None 0.00 0.00 0.00 0.0 5023.15 2.02 5023.86 6 Cir 0.012 1.0
13 12 18.045 -90.000 None 0.00 0.00 0.00 0.0 5023.86 2.00 5024.22 6 Cir 0.012 1.0
14 13 23.068 0.000 None 0.11 0.00 0.00 0.0 5024.22 1.99 5024.68 6 Cir 0.012 1.0
15 9 10.605 90.000 None 0.11 0.00 0.00 0.0 5024.13 5.00 5024.66 6 Cir 0.012 1.0
16 5 46.957 -90.000 None 0.00 0.00 0.00 0.0 5023.58 0.49 5023.81 8 Cir 0.012 1.0
17 16 30.319 0.000 None 0.00 0.00 0.00 0.0 5023.81 0.49 5023.96 8 Cir 0.012 1.0
18 17 10.708 90.000 None 0.11 0.00 0.00 0.0 5024.01 5.04 5024.55 6 Cir 0.012 1.0
19 13 16.188 90.000 None 0.11 0.00 0.00 0.0 5024.22 1.98 5024.54 6 Cir 0.012 1.0
20 8 10.253 90.000 None 0.11 0.00 0.00 0.0 5024.00 4.97 5024.51 6 Cir 0.012 1.0
21 16 12.054 90.000 None 0.11 0.00 0.00 0.0 5023.89 5.06 5024.50 6 Cir 0.012 1.0
22 10 1.559 0.000 None 0.00 0.00 0.00 0.0 5024.17 1.28 5024.19 8 Cir 0.012 1.0
23 22 6.286 -90.000 None 0.00 0.00 0.00 0.0 5024.27 2.07 5024.40 6 Cir 0.012 0.�
Project File: Storm Drain - West.stm Number of lines: 31
Storm Sewer Inventory Report
Line Alignment Flow Data Physical Data
No.
Dnstr Line Defl Junc Known Drng Runoff Inlet Invert Line Invert Line Line N J-Lo
Line Length angle Type Q Area Coeff Time EI Dn Slope EI Up Size Shape Value Coei
No. (ft) (deg) (cfs) (ac) (C) (min) (ft) (°/a) (ft) (in) (n) (K)
24 23 3.500 22.500 None 0.11 0.00 0.00 0.0 5024.40 2.01 5024.47 6 Cir 0.012 1.0
25 22 1.303 0.000 None 0.00 0.00 0.00 0.0 5024.19 0.79 5024.20 8 Cir 0.012 0.7
26 25 11.371 -45.000 None 0.11 0.00 0.00 0.0 5024.20 0.97 5024.31 8 Cir 0.012 1.0
27 17 6.651 0.000 None 0.00 0.00 0.00 0.0 5023.96 0.60 5024.00 8 Cir 0.012 1.0
28 27 43.302 90.000 None 0.00 0.00 0.00 0.0 5024.00 0.48 5024.21 8 Cir 0.012 0.7
29 28 8.891 45.000 None 0.11 0.00 0.00 0.0 5024.21 0.56 5024.26 8 Cir 0.012 1.0
30 6 10.706 -90.000 None 0.11 0.00 0.00 0.0 5023.79 5.04 5024.33 6 Cir 0.012 1.0
31 12 17.341 0.000 None 0.11 0.00 0.00 0.0 5023.86 1.96 5024.20 6 Cir 0.012 1.0
Project File: Storm Drain - West.stm Number of lines: 31
Storm Sewer Summary Report
Line Line ID Flow Line Line Line Invert Invert Line HGL HGL Minor
No. rate Size shape length EL Dn EL Up Slope Down Up loss
(cfs) (in) (ft) (ft) (ft) (°/a) (ft) (ft) (ft)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
PIPE 1
PIPE 2
PIPE 3
PIPE 4
PIPE 5
PIPE 12
PIPE 13
PIPE 14
PIPE 15
PIPE 16
PIPE 16-1
PIPE 5-1
PIPE 5-2
PIPE 5-3
PIPE 15-1
PIPE 6
PIPE 7
PIPE 7-1
PIPE 5-5
PIPE 14-1
PIPE 6-1
PIPE 17
PIPE 17-1
PIPE 17-2
Project File: Storm Drain - West.stm
1.32
1.32
1.32
1.32
0.99
0.66
0.55
0.55
0.44
0.33
0.11
0.33
0.22
0.11
0.11
0.33
0.22
0.11
0.11
0.11
0.11
0.22
0.11
0.11
8
8
8
8
8
8
8
8
8
8
6
6
6
6
6
8
8
6
6
6
6
8
6
6
NOTES: Return period = 100 Yrs. ;*Surcharged (HGL above crown).
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
Cir
14.905 5022.68
7.063 5022.75
28.803 5022.79
28.064 5022.93
60.555 5023.07
13.690 5023.58
10.647 5023.71
9.992 5023.82
13.097 5023.92
11.820 5024.05
9.253 5024.25
35.089 5023.15
18.045 5023.86
23.068 5024.22
10.605 5024.13
46.957 5023.58
30.319 5023.81
10.708 5024.01
16.188 5024.22
10.253 5024.00
12.054 5023.89
1.559 5024.17
6.286 5024.27
3.500 5024.40
5022.75
5022.79
5022.93
5023.07
5023.38
5023.71
5023.82
5023.92
5024.05
5024.17
5024.72
5023.86
5024.22
5024.68
5024.66
5023.81
5023.96
5024.55
5024.54
5024.51
5024.50
5024.19
5024.40
5024.47
0.468
0.567
0.487
0.498
0.512
0.949
1.032
1.002
0.992
1.016
5.082
2.023
1.997
1.994
5.000
0.490
0.494
5.043
1.976
4.972
5.060
1.284
2.066
2.009
5023.22 5023.42 0.17
5023.58" 5023.65� 0.10
5023.75* 5024.05� 0.22
5024.27'` 5024.55� 0.22
5024.78" 5025.12� 0.13
5025.25'` 5025.28� 0.06
5025.34* 5025.36' 0.04
5025.40` 5025.41� 0.04
5025.45'` 5025.47' 0.02
5025.49` 5025.50' 0.01
5025.51' S025.51" 0.00
5024.78* 5024.88� 0.04
5024.92' 5024.95" 0.02
5024.97 5024.97 0.01
5025.49` 5025.49� 0.00
5025.25* 5025.28' 0.01
5025.29` 5025.30� 0.01
5025.31* 5025.31' 0.00
5024.97 5024.97 0.01
5025.45' S025.45' 0.00
5025.29* 5025.29� 0.00
5025.51' 5025.51� 0.01
5025.52' S025.52• 0.00
5025.52` 5025.52� 0.00
Number of lines: 31
Storm Sewer Summary Report
Line Line ID Flow Line Line Line Invert Invert Line
No. rate Size shape length EL Dn EL Up Slope
(cfs) (in) (ft) (ft) (ft) (°/a)
25 PIPE 18 0.11 8 Cir 1.303 5024.19 5024.20 0.787
26 PIPE 19 0.11 8 Cir 11.371 5024.20 5024.31 0.966
27 PIPE 8 0.11 8 Cir 6.651 5023.96 5024.00 0.602
28 PIPE 9 0.11 8 Cir 43.302 5024.00 5024.21 0.485
29 PIPE 11 0.11 8 Cir 8.891 5024.21 5024.26 0.560
30 PIPE 12-1 0.11 6 Cir 10.706 5023.79 5024.33 5.044
31 PIPE 5-4 0.11 6 Cir 17.341 5023.86 5024.20 1.963
Project File: Storm Drain - West.stm
NOTES: Return period = 100 Yrs. ;*Surcharged (HGL above crown).
HGL HGL Minor
Down Up loss
(ft) (ft) (ft)
5025.52` 5025.52� 0.00
5025.52' S025.52` 0.00
5025.31* 5025.31� 0.00
5025.31' 5025.31� 0.00
5025.31" 5025.31� 0.00
5025.34'` 5025.34� 0.00
5024.92" 5024.93' 0.00
Number of lines: 31
Hydraulic Grade Line Computations
Line Size Q Downstream
Invert HGL Depth Area Vel Vel EGL
elev elev head elev
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
8
8
8
8
8
8
8
8
8
8
6
6
6
6
6
8
8
6
6
6
6
8
1.32 5022.68 5023.22 0.54 0.30 4.34
1.32 5022.75 5023.58 0.67 0.35 3.78
1.32 5022.79 5023.75 0.67 0.35 3.78
1.32 5022.93 5024.27 0.67 0.35 3.78
0.99 5023.07 5024.78 0.67 0.35 2.84
0.66 5023.58 5025.25 0.67 0.35 1.89
0.55 5023.71 5025.34 0.67 0.35 1.58
0.55 5023.82 5025.40 0.67 0.35 1.58
0.44 5023.92 5025.45 0.67 0.35 1.26
0.33 5024.05 5025.49 0.67 0.35 0.95
0.11 5024.25 5025.51 0.50 0.20 0.56
0.33 5023.15 5024.78 0.50 0.20 1.68
0.22 5023.86 5024.92 0.50 0.20 1.12
0.11 5024.22 5024.97 0.50 0.20 0.56
0.11 5024.13 5025.49 0.50 0.20 0.56
0.33 5023.58 5025.25 0.67 0.35 0.95
0.22 5023.81 5025.29 0.67 0.35 0.63
0.11 5024.01 5025.31 0.50 0.20 0.56
0.11 5024.22 5024.97 0.50 0.20 0.56
0.11 5024.00 5025.45 0.50 0.20 0.56
0.11 5023.89 5025.29 0.50 0.20 0.56
0.22 5024.17 5025.51 0.67 0.35 0.63
Project File: Storm Drain - West.stm
0.29
0.22
0.22
0.22
0.13
0.06
0.04
0.04
0.02
0.01
0.00
0.04
0.02
0.00
0.00
0.01
0.01
0.00
0.00
0.00
0.00
0.01
Len
Invert
elev
) (ft) (ft)
Upstream
HGL Depth Area Vel Vel
elev head
(ft) (ft) (sqft) (ft/s) (ft)
5023.52 1.033 14.905 5022.75 5023.42 0.67 0.35 3.78 0.22
5023.80 1.018 7.063 5022.79 5023.65 0.67 0.35 3.78 0.22
5023.97 1.018 28.803 5022.93 5024.05 0.67 0.35 3.78 0.22
5024.49 1.018 28.064 5023.07 5024.55 0.67 0.35 3.78 0.22
5024.90 0.573 60.555 5023.38 5025.12 0.67 0.35 2.84 0.13
5025.30 0.255 13.690 5023.71 5025.28 0.67 0.35 1.89 0.06
5025.38 0.177 10.647 5023.82 5025.36 0.67 0.35 1.58 0.04
5025.43 0.177 9.992 5023.92 5025.41 0.67 0.35 1.58 0.04
5025.48 0.113 13.097 5024.05 5025.47 0.67 0.35 1.26 0.02
5025.50 0.064 11.820 5024.17 5025.50 0.67 0.35 0.95 0.01
5025.52 0.033 9.253 5024.72 5025.51 0.50 0.20 0.56 0.00
5024.82 0.295 35.089 5023.86 5024.88 0.50 0.20 1.68 0.04
5024.94 0.131 18.045 5024.22 5024.95 0.50 0.20 1.12 0.02
5024.97 0.033 23.068 5024.68 5024.97 0.29 0.12 0.93 0.01
5025.50 0.033 10.605 5024.66 5025.49 0.50 0.20 0.56 0.00
5025.26 0.064 46.957 5023.81 5025.28 0.67 0.35 0.95 0.01
5025.30 0.028 30.319 5023.96 5025.30 0.67 0.35 0.63 0.01
5025.31 0.033 10.708 5024.55 5025.31 0.50 0.20 0.56 0.00
5024.97 0.033 16.188 5024.54 5024.97 0.43 0.18 0.61 0.01
5025.46 0.033 10.253 5024.51 5025.45 0.50 0.20 0.56 0.00
5025.30 0.033 12.054 5024.50 5025.29 0.50 0.20 0.56 0.00
5025.52 0.028 1.559 5024.19 5025.51 0.67 0.35 0.63 0.01
Number of lines: 31
; c= cir e= ellip b= box
Hydraulic Grade Line Computations
Line Size Q Downstream
Invert HGL Depth Area Vel Vel EGL
elev elev head elev
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft)
23
24
25
26
27
28
29
30
31
6
6
8
8
8
8
8
6
6
Len
Invert
elev
) (ft) (ft)
Upstream
HGL Depth Area Vel Vel
elev head
(ft) (ft) (sqft) (ft/s) (ft)
0.11 5024.27 5025.52 0.50 0.20 0.56 0.00 5025.52 0.033 6.286 5024.40 5025.52 0.50 0.20 0.56 0.00
0.11 5024.40 5025.52 0.50 0.20 0.56 0.00 5025.53 0.033 3.500 5024.47 5025.52 0.50 0.20 0.56 0.00
0.11 5024.19 5025.52 0.67 0.35 0.32 0.00 5025.52 0.007 1.303 5024.20 5025.52 0.67 0.35 0.32 0.00
0.11 5024.20 5025.52 0.67 0.35 0.32 0.00 5025.52 0.007 11.371 5024.31 5025.52 0.67 0.35 0.32 0.00
0.11 5023.96 5025.31 0.67 0.35 0.32 0.00 5025.31 0.007 6.651 5024.00 5025.31 0.67 0.35 0.32 0.00
0.11 5024.00 5025.31 0.67 0.35 0.32 0.00 5025.31 0.007 43.302 5024.21 5025.31 0.67 0.35 0.32 0.00
0.11 5024.21 5025.31 0.67 0.35 0.32 0.00 5025.31 0.007 8.891 5024.26 5025.31 0.67 0.35 0.32 0.00
0.11 5023.79 5025.34 0.50 0.20 0.56 0.00 5025.34 0.033 10.706 5024.33 5025.34 0.50 0.20 0.56 0.00
0.11 5023.86 5024.92 0.50 0.20 0.56 0.00 5024.93 0.033 17.341 5024.20 5024.93 0.50 0.20 0.56 0.00
Project File: Storm Drain - West.stm
; c= cir e= ellip b= box
Number of lines: 31
Storm Sewer Profile
� � N C7 V' �
� 7 7 � 7
_� c J(;,�0 c J�O c J MO c J�O c J O c
O � 00 � LL� t17 � m� � (h M � f� I� � CO OD
"` CO � CO I'� I� � N 1�- I� N:O � CA CO O O � M�
O,^iN O ONN (p pNN f� ONN M OMM m�MM
G; N 6� �NN ��NN I�. �NN ap �NN M NNN
O OO OO OO � O� '�OO
Elev. (ft) o�,n v�,n�n N w,n,n �o W,n,o � W,n,n M:n�n�n
n
c UW o-aww o-aww o-aWW o-aWW � WWW
� � > � E>> � E» ;g E» ;? E» V �»
c1?�_1 � t%) (.�cc ��cc � Ur cc � Ur cc ��cc
5035.00 �
5032.00
5029.00
5026.00
5023.00
� � �
�- N
3 � 7 �
� �O � � v0 � � 00
J � � � �COCO J �O(
� �NOJ � ��� � NO:
M Ch C9 ^J M M
M 7NN � �NN M �N<
00 00 O<
� w �n �n � W �n �n � W �n �
+ -oWW N -pWW N -pWL
� �>> � Ei> ;a �>
v� t��� v� C��� cn C��.
il��rr.
5020.00 ' ' ' ' ' ' '
0 25 50 75 100 125 150
HGL- EGL Reach (ft)
175 200 225 25(
Storm Sewer Profile
� � N M V
7 � � �
Elev. (ft)
5035.00
5032.00
5029.00
5026.00
5023.00
5020.00
HGL EGL
Re
0 25 50 75 100
Channel Report
Hydraflow Express Extension for Autodesk0 Civil 3D0 by Autodesk, Inc.
Curb Channel A: 100 yr Event
Rectangular
Bottom W idth (ft) = 2.00
Total Depth (ft) = 0.50
Invert Elev (ft) = 1.00
Slope (%) = 0.50
N-Value = 0.013
Calculations
Compute by: Known Q
Known Q (cfs) = 1.52
Elev (ft)
2.00
1.75
1.50
1.25
1.00
0.75
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Known Q is the accumulative 100-yr release experienced
that the proposed Prospect Road curb chase.
Section
Thursday, Apr 22 2021
= 0.27
= 1.520
= 0.54
= 2.81
= 2.54
= 0.27
= 2.00
= 0.39
1
�
5 1
1.5
Reach (ft)
2 2.5
Depth (ft)
1.00
0.75
0.50
0.25
� � �'
-0.25
3
Channel Report
Hydraflow Express Extension for Autodesk0 Civil 3D0 by Autodesk, Inc.
Curb Channel B: 100 yr Event
Rectangular
Bottom W idth (ft) = 2.00
Total Depth (ft) = 0.50
Invert Elev (ft) = 1.00
Slope (%) = 1.00
N-Value = 0.013
Calculations
Compute by: Known Q
Known Q (cfs) = 2.40
Elev (ft)
2.00
1.75
1.50
1.25
1.00
0.75
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Known Q is the flow developed by Basin B2.
Section
Thursday, Apr 22 2021
= 0.29
= 2.400
= 0.58
= 4.14
= 2.58
= 0.36
= 2.00
= 0.56
1
�
5 1
1.5
Reach (ft)
2 2.5
Depth (ft)
1.00
0.75
0.50
0.25
� � �'
-0.25
3
Weir Report
Hydraflow Express Extension for Autodesk0 Civil 3D0 by Autodesk, Inc.
Pond B Weir: 100 yr Event
Rectangular Weir
Crest = Sharp
Bottom Length (ft) = 39.33
Total Depth (ft) = 0.60
Calculations
Weir Coeff. Cw = 3.33
Compute by: Known Q
Known Q (cfs) = 4.73
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Top Width (ft)
Known Q is the cumulative flow developed by Basin B1, B2,
and B3, in addition to 0.30-cfs per "The Slab" report.
Depth (ft)
1.00
0.50
� ��
-0.50
Pond B Weir: 100 yr Event
Thursday, Apr 22 2021
= 0.11
= 4.730
= 4.29
= 1.10
= 39.33
Depth (ft)
1.00
0.50
� ��
-0.50
0 5 10 15 20 25 30 35 40 45 50
Weir W.S. Length (ft)
Weir Report
Hydraflow Express Extension for Autodesk0 Civil 3D0 by Autodesk, Inc.
Pond C Weir: 100 yr Event
Rectangular Weir
Crest = Broad
Bottom Length (ft) = 9.00
Total Depth (ft) = 0.50
Calculations
Weir Coeff. Cw = 2.60
Compute by: Known Q
Known Q (cfs) = 1.57
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Top Width (ft)
Known Q is the cumulative flow developed by Basin C1 & C2.
Depth (ft)
1.00
0.50
� ��
-0.50
Pond C Weir: 100 yr Event
Tuesday, Apr 27 2021
= 0.16
= 1.570
= 1.48
= 1.06
= 9.00
v
Depth (ft)
1.00
0.50
� ��
-0.50
0 1 2 3 4 5 6 7 8 9 10 11
Weir W.S. Length (ft)
PPENDIX
REFERENCED MATERIALS
Stormwater
Alternative ComplianceNariance Application
City of Fort Collins Water Utilities Engineering
Engineer Name Kevin BrBzelton Phone 970-530-4044
Street Address 1501 Academy Court Suite 203
City Fort Collins State CO Z�p 80525
Owner Name Maxiimo Development Group (Attn: Christian Bachelet) Phone 970-566-2948
Street Address 706 South College Avenue, Suite 207
City Fort Collins
State CO Z i p 80524
Project Name Haven Apartments
Project/Application Number from Development Review (i.e. FDP123456)
Legal description and/or address of property Lot 2 of the Slab Property Subdivision
Description of Project The restoration of two existing on-site single-family residences and the
construction of a new 14,000 sf footprint apartment building.
Existing Use (check one): �' residential �" non-residential C�' mixed-use i' vacant ground
Proposed Use (check one): (:' residential C` non-residential C' mixed-use � other
If non-residential or mixed use, describe in detail
State the requirement from which alternative compliance/variance is sought. (Please include
applicable Drainage Criteria Manual volume, chapter and section.)
Chapter 6(Detention), Section 1.1 Master Plan Requirements, Typical Release Rates
What hardship prevents this site from meeting the requirement?
See attached.
What alternative is proposed for the site?
See attached.
Attach separate sheet if necessary
Attach separate sheet if necessary
page 2
The owner agrees to comply with the provisions of the zoning ordinance, building code and all other
applicable sections of the City Code, Land Use Code, City Plan and all other laws and ordinances
affecting the construction and occupancy of the proposed building that are not directly approved by
this variance. The owner understands that if this variance is approved, the structure and its occupants
may be more susceptible to flood or runoff damage as well as other adverse drainage issues.
Signature of
The engineer hereby certifies that the above information, along with the reference plans and project
descriptions is correct.
Signature of engineer: �� - Date: ��1� 1�/�
�p0 REG�
p'y P►N��-�'•.
Date complete application submitted:
e: /t�� � � - /`3
#1;� �8837 � ; #
�� /q(ii�rg =.
... ���
�����
PE STAM P
Date of approval/deniat: Variance: ❑ approved ❑ denied
Staffjustification/notes/cond itions:
Approved by:
Entered in UtilityFile Database? �yes �no
��UNITED CIVIL
Design Group
What hardship prevents this site from meeting the requirement?
Stormwater Variance Request
Haven Apartments
Fort Collins, CO
The Old Town Master Drainage Basin requires that detention release rates be limited to the 2-year historic
event. The east residence has a historical designation which limits drainage solutions adjacent to the
building (i.e. a standard open detention pond adjacent to the building will not be allowed). Due to the lack
of public storm sewer adjacent to the site and that the location of the existing detention pond is uphill from
the eastern residence, Basins C1 and C2 of the site cannot be detained and the release from these basins
exceed the 2-year historic event. Therefore, limiting the site release rate to the 2-year historic event will
not be feasible.
What a/ternative is proposed for the site?
The development is proposing to limit the release rate from the site to the 100-year historic condition. To
do so, the development will expand the existing detention pond and over-detain flows intercepted by the
pond to the extent feasible. Additionally, the development will provide a small underground detention pond
south of the existing eastern residence to provide water quality and detention for as much site area as
feasible. Together, the site will hold the total release to Prospect Avenue to the 100-year historic event.
>
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USDA United States
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Natural
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Area, Colorado
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° N Meters °
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Map projection: Web Mercator Comer coordinates: WGS84 Edge dcs: U1T1 Zone 13N WGS84
9
Custom Soil Resource Report
MAP LEGEND
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
� _� Soil Map Unit Lines
0 Soil Map Unit Points
Special Point Features
v Blowout
C`� Borrow Pit
j�' Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
• Lava Fiow
_ Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
' Saline Spot
lSandy Spot
= Severely Eroded Spot
Sinkhole
Slide or Slip
oa Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
, Special Line Features
Water Features
Streams and Canais
Trensportation
,+* Rails
ti Interstate Highways
US Routes
Major Roads
Local Roads
Background
� Aerial Photography
MAPINFORMA
The soil surveys that comprise your AOI �
1:24, 000.
Warning: Soil Map may not be valid at thi
Enlargement of maps beyond the scale o
misunderstanding of the detail of mappin�
line placement. The maps do not show th
contrasting soils that could have been sh
scale.
Please rely on the bar scale on each maF
measurements.
Source of Map: Natural Resources Con
Web Soil Survey URL:
Coordinate System: Web Mercator (EP
Maps from the Web Soil Survey are base
projection, which preserves direction and
distance and area. A projection that pres�
Albers equal-area conic projection, shoul
accurate calculations of distance or area
This product is generated from the USOP
of the version date(s) listed below.
Soil Survey Area: Larimer County Area
Survey Area Data: Version 13, Sep 10,
Soil map units are labeled (as space allo�
1:50,000 or larger.
Date(s) aerial images were photographec
12, 2018
The orthophoto or other base map on wh
compiled and digitized probably differs fr�
imagery displayed on these maps. As a r
shiftinq of map unit boundaries may be e
10
Custom Soil Resource Report
Map Unit Legend
Map Unit Symbol � Map Unit Name � Acres in AOI � Percent of AOI
Altvan-Satanta loams, 0 to 3 3.1 100.0%
percent slopes
Totals for Area of Interest
Map Unit Descriptions
3.1 I 100.0%
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
11
Custom Soil Resource Report
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
12
Custom Soil Resource Report
Larimer County Area, Colorado
3—Altvan-Satanta loams, 0 to 3 percent slopes
Map Unit Setting
National map unit symbol: jpw2
Elevation: 5,200 to 6,200 feet
Mean annual precipitation: 13 to 15 inches
Mean annual air temperature: 48 to 50 degrees F
Frost-free period: 135 to 150 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Altvan and similar soils: 45 percent
Satanta and similar soils: 30 percent
Minor components: 25 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Altvan
Setting
Landform: Benches, terraces
Landform position (three-dimensional): Side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 18 inches: clay loam, loam, sandy clay loam
H2 - 10 to 18 inches: loam, fine sandy loam, silt loam
H2 - 10 to 18 inches: gravelly sand, gravelly coarse sand, coarse sand
H3 - 18 to 30 inches:
H3 - 18 to 30 inches:
H3 - 18 to 30 inches:
H4 - 30 to 60 inches:
H4 - 30 to 60 inches:
H4 - 30 to 60 inches:
Properties and qualities
Slope: 0 to 3 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat)
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding.� None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Moderately high to
Available water storage in profile: Very high (about 13.2 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 3e
13
Custom Soil Resource Report
Hydrologic Soil Group: B
Hydric soil rating: No
Description of Satanta
Setting
Landform: Terraces, structural benches
Landform position (three-dimensional): Side slope, tread
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Mixed alluvium and/or eolian deposits
Typical profile
H1 - 0 to 9 inches: loam
H2 - 9 to 18 inches: loam, clay loam, sandy clay loam
H2 - 9 to 18 inches: loam, clay loam, fine sandy loam
H2 - 9 to 18 inches:
H3 - 18 to 60 inches:
H3 - 18 to 60 inches:
H3 - 18 to 60 inches:
Properties and qualities
Slope: 0 to 1 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.60 to 2.00 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 10 percent
Available water storage in profile: Very high (about 27.4 inches)
Interpretive groups
Land capability classification (irrigated): 1
Land capability classification (nonirrigated): 3c
Hydrologic Soil Group: B
Hydric soil rating: No
Minor Components
Nunn
Percent of map unit: 10 percent
Hydric soil rating: No
Larim
Percent of map unit: 10 percent
Hydric soil rating: No
Stoneham
Percent of map unit: 5 percent
Hydric soil rating: No
14
�e� em�er � •
t
t City of For� Coliins Approved Plans
Approved by:
, . Date: '% �20��,
� '
0
Prepared for:
Maxiiimo Devetopment Group
70b S. College Avenue, Suite 201
. Fort Collins, CO 8024
Prepared by: .
� NORTHERN
ENGINEERING
301 Narth Howes Street, Suite 100
FoR Collins, Cobrado 80521
Phone:970.221.4158 Fax:970_221.4159
www.noRhemer�need�.com
� This Dralnage Report Is conscto�sly provided as a PDF.
Please consfder the mWronment before printieg thls dxument in its endrety.
Whm a hard copy is absoluEely neceasary, we rceommend douDle-sided priitting. P�OJ@Ct NUn'lb@f: 1033-001
his unofficial copy was downloaded on Aug-Ol -2019 from the Ciry of Fort Collins Public Records Website: http://citydocs.fcgov.com
NortheraEnaine or addirioi7al information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
'
�
� I NORTHERN
ENGINEERING
"�3�'� �� Y�,fi,�'��»t3;��: ���i�f�T� f�'s � �(� 43i�
September 21 � 2016
:t`� �K�IC� ��,�
._._.__._.,��,...___ � _ _ .. �......�. .
.___..�:.:City.of_Fort.Collins....�.��.. ���"'�
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage Report for
The Slab
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report for
your review. This report accompanies the Final Development Review submittal for the proposed
The Slab. Comments from the Final Review Letter dated June 1, 2016 have been addressed.
Written responses thereto can be found in the comprehensive response to comments letter on file
with Current Planning.
This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM),
and setves to document the stormwater impacts associated with the proposed The Slab 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.
� ��
Nicholas W. Haws, PE LEED �
Project Manager AP
., � �
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�
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Co Snowdon
Projact Engineer
�
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� unofficial copy was downloaded on Aug-Ol -2019 from the Ciry of Fort Collins Public Records Website: http://citydocs.fcgov.com
addirional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
�
�
NORTNERN
ENG i NEERIN6
B. Description of Prope
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The Slab
11. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The Slab is iocated within the Old Town Basin, which is located primarily in 41d Town
Fort Collins. .
B. Sub-Basin Description
1. This property and project were previously analyzed in August, 2007 by DMW Civil
Engineers. To honor the historic drainage patterns, the historic analysis from that
' report wilf be preserved throughout this analysis. Within that analysis, the site was
divided into three on-site historic basins (El-3} and one off-site historic basin (E01).
Basin E1 consisted of the northem half of the site and routed stormwater via overland
flow to the nartheast corner of the site. E2 consisted of the southem po�tion af the
site and routed stormwater via overland flaw to the southern property line. Basin E3
consisted of the area within Prospect Road public right-of-way and routed stormwater
via gutter flow to the east. Off-Site Basin E01 consist entirely of the off-site
emergency access easement and routes stormwater via overland flow north to Lake
Street. A more detailed description of the projects propased drainage pattems follows
in Section IV.A.4., below. - '
2. There is a portion of the single family residence neighboring the project to the west
that drains onto this property. The area is 0.370 acres and consists mostly of the
backyard between the house and the garage, as well as a portion of both the house
and garage. Drainage is routed via overland flow and sheet flows across the westem
boundary of the project. The proposed design will preserve this route and plans to
pass the flow through the project. This basin has been delineated as Basin OW1 and
discharges Q.66 cfs and 1.2 cfs for the 2-year & 100-year event, respectively.
A full-size copy af the previously approved Drainage Plan by DMW Civil Engineers and
� the proposed Drainage Exhibit can be found in the Map Pocket at the end of this
report.
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' Flt1 his unofficial copy was downloaded on Aug-01-2019 from the City of Fort Collins Public Rewrds Website: http://citydocs.fcgov.com �
ar addirional information or an official copy, please contact City of Port Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
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IV. DRAINAGE FACILITY DESlGN
A. General Concept
1. The main objectives of The Slab drainage design are to maintain existing drainage
patterns and ensure no adverse impacts to any adjacent properties. '
2. The existing site does have off-site flows from the west that historically drain onto the
property. The current routing of this runoff will remain as is and pass through the
proposed project.
3. A list of tables and figures used within this report can be found in the Table of
Con#ents at the front of the document. The tabies and figures are located within the
sections to which the content best applies.
4. The Slab project is composed af three majar drainage basins, designated as Major
Basins N, Major Basin S and Majar Basin 0. Major Basin N is further subdivided into
three {3) sub-basins, designated as Sub-Basins N1-N3. Major Basin S is further
subdivided into four (4} sub-basins, designated as Sub-Basins S1-S4. Majar Basin 0
is further subdivided into three (3} sub-basins, designated as Sub-Basins ON1� OWl,
and OS1. The drainage patterns anticipated for Major Basins N, S and OS and
associated sub-basins are #urther described below.
Basin N � � •
Basin N consists of all of the on-site improvements being proposed north of the
existing concrete building slab. The major basin was divided into three (3) sub-basins
to bettec size the LID concepts proposed on the northern side of the property. Sub-
Basin N 1 encompasses the furthest downstream reach of Major Basin N and consists
af a portion of the parking area and the en#ire Northern Detention Pond. The runoff
from this basin is routed via overland flow and discharges directly into the proposed
detention pond through a curb cut located at the eastern edge of the proposed
parking. Sub-Basin N2 encompasses the northern partion of the parking area and the
northern half of the proposed building. Runoff from this sub-basin drains via overland
flow and is intercepted by an inlet located within the parking island. The water quality
event will be routed into the undergraund StormTech Chambe�s, which proVide LID
treatment, while all events exceeding that volume will be routed through a curb cut
into Sub-Basin�Nl. Sub-Basin N3 encompasses the southern portion of the parking
area and is composed primarily of asphalt. Runoff from this sub-basin drains via
overland flow and is intercepted by an inlet located within the parking island. The
water quality event will be routed into the underground StormTech Chambers, which
provide LID treatmen#, while all events exceeding that volume will be routed through a
curb cut into Sub-Basin N2.
Basin S
Basin S consists of all of the on-site improvements being proposed wsst, east, and
south of the existing concrete building slab. The major basin was divided into four {4}
sub-basins to better size the LID concepts proposed on the west, east and south sides
of the property. Sub-Basin S1 encornpasses the furthest downstream reach of Major
Basin S and consists of east of the proposed building. The runoff from this basin is
routed via overland flow across a grass buffer yard and discharges off-si#e where it is
intercepted by an area inlet and discharged directly into the Southern Detention Pond.
Basin S2 encompasses the southem portion of the building and the area surrounding
� unofficial copy was downloaded on Aug-01-2019 from the City of Fort Collius Public Records Website: http://citydocs.fcgov.com I 9
additional information or an ofticial copy, please contact Ciry of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
�`� I NORTHERN
EN&INEERIN6
The Slab �
the building to the sauth. This area consists of the proposed building and the
surrounding landscape areas. The runoff from this area will be routed via overland
flow and roof leaders inta a bio- swale. The runoff conveyed through the bio-swale is
intercepted by an area inlet and routed directly into the Southern Deten#ion Pond.
Sub-Basin S3 encompasses the western portion of the building and drive aisle and is
primarily composed of hardscapes. The runoff from the roof wi11 be routed via
underground pipe into the underground StormTech Chambers. The runoff from the
remaining area will be routed via overland flow to a curb cut and discharge d'+rectly
into Sub-basin S4. Sub-Basin S4 encompasses the furthest upstream reach of Major
Basin S and consists of westem portion of the project. The runoff from this basin is
routed via overland flow into a small depression located at the southwest corner of the
property. Runoff from this basin is intercepted by a storm pipe and routed into the
underground StormTech Chambers. The underground StormTech Chambe�s have ,
been sized to handle the water quality event. All events exceeding this voEume will
bypass the chambers and be routed directly into the Southern Detention Pond.
Basin 0
Basin 0 consists of all of the off-site improvements being proposed. The major basin
was divided into three (3} sub-basins all draining undetained in three different
directions. Sub-Basin OW1 encompasses the area along the western edge af the site
that historically drains across the site from the west. This includes a portion of the
existing single family residences, associated backyard and existing garage buildings.
The stormwater is routed via overland flow and sheet fEow anto the praperty along the
western property fine. This stormwater is planned to be routed through the site and
released undetained at historic rates. Sub-Basin OS1 encompasses the existing public
right-of-way within Prospec# Road. Other than the proposed entrance and the master
planned public sidewalk, no ather improvements are proposed. The stormwater is
routed via overland and gutter flow and is released off-site, undetained east on
Prospect Road. Sub-Basin ON1 encompasses the emergency access drive located to
the north of the site. The stormwater is routed via overland and swale flow. A portion
of the runoff is planned to be detained within a TrueGrid and drain rack section and
released partially through infiltra#ion and partial through an underdrain sysfem.
Another portion of the runoff is planned to be captured through infiltration within the
bio-swale and the use of a dry well. Emergency overflow is planned to over #op and
be routed through a sidewalk chase and into Lake Street.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this repart.
B. Specific Details
1. Ons of the main drainage problems associated with this project site is the deficiency
of water quality present wi#hin the existing site. Currently the entire site drains
overland and discharges directly into either Lake Street or Prospect Road without
water quality. The proposed site will mitigate this issue by instituting the following
water quality devices:
� Al! of the runoff generated from the proposed building will either be routed through
drainage rock surrounding underground StormTech Chambers, into an engineered
bio-swale or over a grass buffer section.
� Most of the improvements generated from the parking lot will be routed through a
sub-surface drainage rock surrounding underground StormTech Chambers.
� unofficial copy was downloaded on Aug-01-2019 from the City of Fort Collius Public Records Website: http://citydocs.fcgov.co�n
additional information or an ofticial copy, please contact Ciry of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
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� AEf runoff generated from the emergency access drive will be routed either through
a TrueGrid system and sub-surface drainage rock or through an engineered bia-
swale.
� Law Impact Development Design will be implemented to break up the impervious
areas and promate infiltration.
� The southern de#ention pond is designed with a water quality element and is
designed to slawly release the minor storm into Prospect Road.
2. Since the si#e was partially developed since 2007, the release rate for the
undeveloped land {pre-development) was establ�shed through using the previously
approved quantities as reported by DMW Civil Engineers iRefer to Appendix D for
supporting documentation). The historic 2-vear peak runoff rate was established for
the entire project area excluding the partion of public right-of-way that contains the
front landscape area designated as Basin OS1 and excluding the off-site emergency
access drive to the north. The total establishes the overall maximum allowable release
rate, 1.1 cfs, from the on-site improvements, in which 0.8 cfs drains to the north into
Lake Street and 0.3 cfs drains to the south into Prospect Road. These release rates
were utilized in the FAA procedure detention storage computations (Refer to Appendix
B for these calculations).
3. Within the orignal report, it was assumed that porous concrete would not change or
generate more runoff than historic conditions. Since that time, it has been proven
that porous concrete is not a viable solution and will in fact change the characteristic
and quantity of runoff from historic conditions. Through subsurface exploration, it
was determined that the soils in this area have an infiltration rate of 0.63
inches/hour. To reduce runoff leaving the site, Sub-Basin ON1 (10,820 sq. ft.) is
proposed to be handle completely through intiltra#ion, resulting in an overall release
rate of 0.16 cfs. In establishing a 0.16 cfs release ra#e, Sub-basin wil! require 1,422
cu. ft. of detention that will be stored within the drain rock under the concrete path
and TrueGrid section. The overall storage supplied within the drain rock section is
2,055 cu. ft. and will completely drain within 3.5 hours. Through the use af
infiltration and the drain rock section, the previously approved design concept will be
maintained.
4. The FAA methad was used to size both of the ponds for quantity detention.
Calculations for #he northerrr pond, based on the characteristics of Basin N and an
adjusted release rate of 0.8 cfs, indicate a detention volume of 0.23 acre-feet. No
additional volume is required for water quality with each basin receiving treatmen#
either before or after the detention pond. Below is a table summarizing the results for
the northern detention pond.
Required Water Water Quallty Requlred 100-year Tatal Requlred Hlgh Water
' Quallty Stomge Surface Detention Volume DeterKlon Volume Surface Elewadon Top of Pond
Pond ID (ac-ft) ElevaUon (ft) (ao-ft) (at-ft) (R) Elevatlon (ft)
North Pond 0.000 NA 0.23 0.23 5026.?8 SD27.40
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Table 2- Northem Pond Summary Table
� unofficial copy was downloaded on Aug-01-2019 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com R 1
additional information or an official copy, please contact C�ity of Fort Collins Utilities 700 Wood SCreet Fort Collins, CO 80524 USA �
� NORTHERR
Ek61NEERIN6
Calculations for the southem pond, based on the characteristics of Basin S and
adjusted release rate of 0.3 cfs, indicate a detention volume of 0.1039 acre-feet. At
this point, no additional water quality is required with only a small portion of Basin S
(Sub-Basin S1) not being treated prior to Pond S. This Sub-Basin Si will need to be
accounted for upon the development of Lot 2. With the understanding that Lot 2 will
develop at some paint, calculations have been performed based on a conceptual site
fayout and some design assumptions. Based on the assumed characteristics of the
future developed Lot and Basin S of Lot 1, an overall detention volume oi 0.1379
acre-feet will be required. This volume includes the Water Quality Capture Volume for
both the future developed Lot 2 draining to this pond and Basin S1 located on Lot 1.
Below are two tables summarizing the current requirements and #he assumed future
requirements. For a conceptual analysis of future drainage patterns of Lot 2, refer to
Appendix F.
Requi►ed Water Water Quality Required 100-year Totai Requlred High Water
Quality5torege Su�face Detention Volvme Detention Volume Surtace Elevation Top of Pond
easin �D (ac-ft) Elevation (ft) (ac-fty (ac-ft} tft) �Ievation (it)
South Pond 0.0 NA 0.1039 0.1039 0.00 SU25.60
Table 3- Southern Pond Summary Table
Total OetenUon Volume
Reqidred Water Water Quallty Requlred 300�year (aaR) Hlgh Water
Quallry Storage Surface Detentlan Vdume (w/ 0.0317 aaR Surtaa Elevatlan Top of Pa�d
easln ID (ao-ft) Elevatlon (R) {ac-ft� from Lot 2) (k) Elevation {kj
South Pond wlth Futurc
Developmerrt 0.0024 5022.fi57 0.1039 0.1379 502S.75 5026A0
Table 4- Future Southem Pond Summary Tabfe
5. The emergency spillway for the northern pond will be loca#ed on the eastem wa11. In
the event that emergency overflows occur, the drainage will flow into off-site bio-swale
and into Lake Street. The emergency spiliway for the southern pond will be located
on the southern wall. In the event that emergency averflows occur, the drainage will
fiow directly into Prospect Road.
� unofficial copy was downloaded on Aug-01-2019 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
additional information or an official copy, please contact C�ity of Fort Collins Utilities 700 Wood SCreet Fort Collins, CO 80524 USA
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A. Campliance with Standards
1. The drainage design proposed with The Siab project complies with the City of Fort
Collins' Starmwater Cri#eria Manual. The project is requesting an exception to be
granted by the Utilities Executive Director or his designee to Section 4.15tb). The
project is propasing to use the parking area for additianal detention volume with
depths that exceed the 12-inch maximum. These depths will not exceed 18-inches
within the parking area and the area exceeding 12-inches af ponding will occur within
less that twenty-five percent t25%) of the total pa�king spaces provided. Please see
the full-size copy of�the Proposed Drainage Exhibit within Map Pocket to see the
extents of these ponding areas.
2. The drainage design proposed with The Slab project complies with the City of Fort
Collins' Master Drainage Plan for the Old Town Basin:
3. There are no regulatory floodplains associated with The Slab development.
4. The drainage plan and stormwa#er management measures proposed with The Slab
�. development are compliant with ali applicable State and Federal �egulations governing
stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit potential damage
associated with its stormwater runoff. The Slab will detain for the pervious area
converted to impervious areas by releasing all on-site areas to the 2-year existing rate
during the developed 100-year storm. The off-site basin, Basin ON1, wil! be released
entirely through infiltration further improving dawnstream drainageways.
2. The proposed Slab development wiU not impact the Master Drainage Plan
recommendations for the Old Town major drainage basin.
� Lmofficial copy was downloaded on Aug-01-2019 from the City of Fort Collins Public Records Website: http://cirydocs.fegov.eom
addirional infonnation or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
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EN6IREERIN6
References
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1. Citv of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, �
Novernber 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services.
2. Final Draina�e Report for Observatory Park Fort Collins Colorado, August 27, 2007, DMW �
Civil Engineers.
3. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. �
174, 2011, and referenced in Section 26-500 ic) of the City of Fort Colfins Municipal Code.
4. Larimer Countv Urban Area Street Standards, Adopted January 2, 2001, Repealed and �
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
5. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture. �
6. Urban S#orm Draina�e Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revise� April 2008. �
r-,
� Lmofficial copy was downloaded on Aug-01-2019 from the City of Fort Collins Public Records Website: http://citydocs.fegov.com 14
addirional infonnation or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
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PPENDIX
DRAINAGE EXHIBITS
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EXISTWG � � � � � ��- -
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/ �' -�- I EXISTING �
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�/ % / r � � IMPROVEMENTS
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� I� � f ° RELATED TO "THE SLAB"
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�— —� I. PROPERTY ARE NOT �
/ CONSIDERED IN
� I I �\ HISTORIC CONDITION
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= DATE: March 2. 2020
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PREPARED FOR: MAXIIIMO DEVELOPMENT GROUP JOB NUMBER: U19031 NOTE: THIS EXHIBIT WAS PF