HomeMy WebLinkAboutFile Documents.401 Castle Creek Rd.0071.2018 (27).ACBK Drainage Report
ASPEN AMBULANCE DISTRICT FACILITY
405 CASTLE CREEK RD.
ASPEN, CO
June 22, 2018
Prepared by
Richard Goulding, P.E.
Roaring Fork Engineering
592 Highway 133
Carbondale, CO
06/26/2018
Reviewed by Engineering
07/02/2018 10:43:54 AM
"It should be known that this review shall not
relieve the applicant of their responsibility to
comply with the requirements of the City of
Aspen. The review and approval by the City is
offered only to assist the applicant's
understanding of the applicable Engineering
requirements." The issuance of a permit based
on construction documents and other data shall
not prevent the City of Aspen from requiring the
correction of errors in the construction
documents and other data.
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ASPEN AMBULANCE DISTRICT FACILITY
405 CASTLE CREEK RD.
ASPEN, CO
I HEREBY AFFIRM THAT THIS REPORT FOR THE IMPROVEMENTS AT 405 CASTLE CREEK RD. WAS
PREPARED BY ME FOR THE OWNERS THEREOF IN ACCORDANCE WITH THE PROVISIONS OF THE CITY OF
ASPEN URBAN RUNOFF MANAGEMENT PLAN AND APPROVED VARIANCES AND EXCEPTIONS LISTED
THERETO. I UNDERSTAND THAT IT IS THE POLICY OF THE CITY OF ASPEN THAT THE CITY OF ASPEN
DOES NOT AND WILL NOT ASSUME LIABILITY FOR DRAINAGE FACILITIES DESIGNED BY OTHERS.
RICHARD GOULDING, P.E.
RFE Project # 2017-44
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1.0 Contents
1.0 General .................................................................................................................................. 1
1.1 Existing Site ........................................................................................................................................ 1
1.2 Proposed Conditions ........................................................................................................................... 1
1.3 Previous Drainage Studies .................................................................................................................. 2
1.4 Existing Drainage basins ..................................................................................................................... 2
2.0 Proposed Drainage Basins and Sub-basins ........................................................................... 2
2.1 Proposed Drainage Basins .................................................................................................................. 2
2.2 Peak Discharge Calculations ............................................................................................................... 3
3.0 Low Impact Site Design ........................................................................................................ 4
3.1 Principles............................................................................................................................................. 4
4.0 Hydrological Criteria ............................................................................................................ 5
4.1 Storm Recurrence and Rainfall ........................................................................................................... 5
4.2 Peak Runoff and Storage Volume Methodology ................................................................................ 5
4.2.1 Water Quality Capture Volume ............................................................................................ 5
4.2.2 Detention Volume ................................................................................................................. 6
4.2.3 Doolittle Pond ....................................................................................................................... 6
5.0 Proposed Facilities ................................................................................................................ 7
5.1 Proposed Inlets .................................................................................................................................... 7
5.2 Proposed Pipes .................................................................................................................................... 8
5.3 Existing Storm System Analysis ....................................................................................................... 10
6.0 Operation and Maintenance ................................................................................................ 12
6.1 Parking Lot Deicing .......................................................................................................................... 12
6.2 Storm System Maintenance .............................................................................................................. 12
Appendix A – TOC Calculations ................................................................................................... 13
Appendix B – Inlet Calculations .................................................................................................... 14
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Appendix C – Swale Capacity Calculations .................................................................................. 15
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1.0 General
1.1 Existing Site
The property under evaluation is located at 405 Castle Creek Rd. in Aspen Colorado. The site of the
proposed Aspen Ambulance District Facility (AADF) and parking lot currently consists of two parking
lots, two sheds, sidewalks serving the Health and Human Services Building along with associated
landscaping. The proposed site is bounded by the Health and Human Services building to the south, an
undeveloped hillside to the west, Hospital Loop Road (HLR) to the North and Doolittle Drive to the East.
The existing site generally slopes from the southwest towards the northeast. Curb and gutter along
hospital loop road and a portion of the parking lot loop collects stormwater from the northern portion of
the site that is then conveyed to the existing Aspen Valley Hospital (AVH) storm system through two
inlets along HLR. Curb and gutter along the parking lot, the parking lot loop road and Doolittle Drive
collects stormwater from the southern portion of the site which is then conveyed through an inlet in the
parking lot and one in Doolittle Road to the existing Doolittle pond between Doolittle Drive and Castle
Creek Road.
The geotechnical report completed by CTL Thompson observed that the underlying soil is sand that is
clayey to silty with 31 to 44 percent passing the no. 200 sieve. Ground water was not encountered in the
geotechnical borings.
1.2 Proposed Conditions
This project is classified as a ‘Major Project’ per Table 1.1 of the City of Aspen Urban Runoff
Management Plan (URMP). The proposed development disturbs approximately 46,000 square feet which
is greater than 25% of the site. The intent of this report is to demonstrate compliance with the
requirements of the City of Aspen URMP. The Low Impact Design (LID) Principles in the introduction of
the manual were used as a guide throughout the design process.
The site will consist of a proposed two-level structure for the Ambulance District and a parking lot that
will serve both the AADF and HHS building. A snow melted access drive on the north side of the
building will provide access for the ambulances and other vehicles. Sidewalks will surround the building
to the east and south and provide access to the front and rear entrances to the building. The existing
parking lot and parking lot loop road will be re-configured to provide additional parking for the new
facility as well as the HHS building.
All runoff from the site will be conveyed through a series of area drains, trench drains and street inlets to
either the existing AVH storm system or to the Doolittle Pond. Runoff being conveyed to Doolittle Pond
will first pass through a CDS sediment and hydrocarbon contaminant removal system. Runoff that is
conveyed through the AVH storm system will be collected in the AVH detention pond which has been
confirmed to have sufficient capacity to treat and detain this additional volume.
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1.3 Previous Drainage Studies
The parcel is not located within the City of Aspen Drainage Master Plan area. The site is located within
the area analyzed by the Aspen Valley Hospital Master Drainage plan completed by Sopris Engineering.
This master drainage plan was referenced to confirm that the existing drainage infrastructure that is in
place will have sufficient capacity for the additional runoff generated due to this project.
1.4 Existing Drainage basins
The existing site is contained within portions of two major drainage basins. Existing basin 1 (EX-1)
consists of a portion of the hillside to the west and southwest, the south half of HLR from the existing
ambulance facility to Doolittle Drive, the majority of the existing western parking lot and surrounding
landscaping. Runoff from this basin is collected by curb and gutter along Hospital Loop Road and
conveyed to the two existing inlets along HLR. These inlets are part of Storm System C of the AVH
storm system and ultimately drain to the existing AVH detention pond.
Existing basin 2 (EX-2) consists of a large portion of the hillside to the southwest of the site including
multiple housing developments. This basin also includes the HHS building, the existing eastern parking
lot, the parking lot loop and portions of Doolittle Drive. Runoff from the hillside to the southwest is
collected by a drainage channel that runs along the south side of the HHS building and parking lot loop
road which is then conveyed through an existing 24” pipe to Doolittle pond. Runoff from the parking lot
loop and the existing southeast parking lot is collected by curb and gutter and conveyed to inlets in the
parking lot and in Doolittle Drive. A 15” concrete pipe connects these two inlets to the Doolittle Pond.
The Doolittle pond contains an outlet pipe that conveys runoff under Castle Creek Road and releases it
into a drainage channel on the hillside to the east.
2.0 Proposed Drainage Basins and Sub-basins
2.1 Proposed Drainage Basins
The proposed work will reconfigure the two existing drainage basins into two proposed drainage basins
that will maintain the flow paths of these existing basins.
Proposed drainage basin 1 (PR-1) will include all of existing basin 1, but will also include the proposed
ambulance facility, the reconfigured parking lot and the north-south portion of the parking lot loop road.
An additional inlet will be added along HLR to capture offsite portions of this basin and the existing
upstream inlet will be replaced. A storm system around the ambulance facility will capture flows from the
surrounding areas and will be connected into the proposed storm system extension along HLR. The
parking lot inlet will be replaced and connected into the existing AVH storm system at the existing
downstream inlet on HLR.
Proposed basin 2 (PR-2) encompasses the hillside to the southwest, the HHS Building, the east-west
portion of the parking lot loop and those portions of Doolittle Road that are already included in existing
basin 2. The existing drainage channel will continue to capture offsite flows from the southeast hillside
and HHS building. The existing inlet in Doolittle Drive will be replaced with a CDS unit that will capture
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the runoff collected by curb and gutter along the parking lot loop and Doolittle drive. This CDS unit will
be connected to the Doolittle pond using the existing 15” pipe under Doolittle Drive.
2.2 Peak Discharge Calculations
The peak flows were calculated for each Major Basin for 10-year and 100-year storm events. The time of
concentration for these basins was calculated using UDFCDs UD-Rational V2.00 spreadsheets in
conjunction with both surveyed and GIS data. These calculations can be found in appendix-1. The 1-hour
Rainfall depths (P1) used for this site were taken from Table 2.2 with values of 0.77 inches for a 10-year
event and 1.23 inches for a 100-year event. Equation 2.1 was referenced when solving for the Rainfall
Intensity (I).
I = 88.8P1/(10+Td )1.052
Runoff Coefficients (C), a function of the Soil Group (in this case C for both basins) and the percentage
of impervious area within each basin were developed using Figure 3.4. The Runoff Coefficient (C) was
then multiplied by the Rainfall Intensity (I) and the area of each the basins (A) to determine the peak
discharge for these major basins.
Qp = CIA
Qp = Peak Discharge (cfs)
A = Area (Acres)
I = Rainfall intensity (inches per hour)
C = Runoff Coefficient
These peak flow values were used to calculate the size of the proposed hydraulic structrures. The tables
below contain the peak flows for existing and proposed basins for 10-year, and 100-year storm events.
10 Year Peak Discharge Calculations
1 Hour(P1)0.77
Return Period 10
Basin ID Total Area Imp. Area Impervious C Value Time of C Intensity Q Max
See(D1)(ft2)(ft2)(%)From Table (Td)I=88.8P1/(10+Td)1.052 (ft3/sec)
EX-1 92469.00 29590.08 32.00%0.380 14.11 2.40 1.94
EX-2 627166.00 163063.16 26.00%0.360 23.37 1.71 8.85
PR-1 124197.00 57130.62 46.00%0.440 13.26 2.50 3.13
PR-2 593668.00 142480.32 24.00%0.350 23.37 1.71 8.14
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3.0 Low Impact Site Design
Low Impact Development (LID) aims to mimic the natural pre-development hydrologic pattern. The goal
is to manage storm water as close to its source as possible.
3.1 Principles
Principle 1: Consider storm water quality needs early in the design process.
Storm water quality needs were considered early in the design process and treatment methods were
incorporated into the overall site design where possible.
Principle 2: Use the entire site when planning for storm water quality treatment.
Storm water quality was considered in the design of every part of the site that is being affected by the
proposed construction.
Principle 3: Avoid unnecessary impervious area.
Impervious areas were kept to a minimum while maintaining the intent of the project.
Principle 4: Reduce runoff rates and volumes to more closely match natural conditions.
The existing detention pond that basin PR-1 is flowing into has an outlet structure that is designed to
match historical flow rates for the 10 and 100-year flow rates.
Principle 5: Integrate storm water quality management and flood control.
The Aspen Valley Hospital detention pond which is being utilized combines water quality treatment and
detention into a single storm water facility.
Principle 6: Develop storm water quality facilities that enhance the site, the community and the
environment.
The western swale was designed to be a stormwater facility that improves the site from a stormwater
drainage and aesthetic standpoint.
Offsite 100 Year Peak Discharge Existing Conditions Calculations
1 Hour(P1)1.23
Return Period 100
Basin ID Total Area Imp. Area Impervious C Value Time of C Intensity Q Max
See(D1)(ft2)(ft2)(%)From Table (Td)I=88.8P1/(10+Td)1.052 (ft3/sec)
EX-1 92469.00 29590.08 32.00%0.570 14.11 3.84 4.65
EX-2 627166.00 163063.16 26.00%0.560 23.37 2.73 21.99
PR-1 124197.00 57130.62 46.00%0.590 13.26 3.99 6.71
PR-2 593668.00 142480.32 24.00%0.550 23.37 2.73 20.44
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Principle 7: Use treatment train approach.
The use of a swale to convey storm water from the western hillside immediately adjacent to the proposed
facility and the runoff from the west half of the roof will function to treat runoff before it enters the storm
system and is then further treated at the AVH detention pond.
Principle 8: Design sustainable facilities that can be safely maintained.
The AADF storm water system has been designed with frequent cleanouts and all street inlets have been
designed to be easily accessed to allow for easy and safe maintenance.
Principle 9: Design and maintain facilities with public safety in mind.
Proper drainage and grading of the entire site reduces ice buildup and dangerous icy conditions. All
grading was done with safety in mind.
4.0 Hydrological Criteria
4.1 Storm Recurrence and Rainfall
The property is not in the commercial core and will not be served by the City Storm System. Since the
site is contained within the area analyzed by the AVH master drainage plan, the site was analyzed to meet
the conveyance requirements for the 10 and 100-year storm events.
The 1-hour Rainfall depth (P1) is given in Table 2.2 as 0.77 inches for the 10-year event and 1.23 inches
for the 100-year event. The intensity in inches per hour for different storm duration (Td) is calculated
using the Equation 2.1 from the Aspen URMP.
4.2 Peak Runoff and Storage Volume Methodology
The storage and water quality volumes for basin PR-1 were calculated to determine if the existing Aspen
Valley Hospital detention pond had sufficient capacity for the additional flows being routed to this pond
as a result of the proposed development. The proposed development results in alterations to basins OS-1,
OS-2 and subbasins C1 and C2, which were combined into basin PR-1 for the purpose of this report.
4.2.1 Water Quality Capture Volume
The water quality volumes for the existing basins and subbasins are 131 ft3 for basin OS1, 140 ft3 for
basin OS2, 200 ft3 for subbasin C1 and 35 ft3 for subbasin C2 according to the AVH master drainage plan.
Subbasin C1 and C2 were originally accounted for in the overall basin 1 WQCV calculations but were
calculated out using the subbasin properties for the purposes of this analysis. The water quality capture
volume for the proposed development for basin PR-1 was calculated to be 921 cf. This results in an
increase of 415 ft3 of required storage. According to the AVH master drainage plan, the detention pond
was designed with 770 ft3 of additional water quality storage than was needed (design WQCV was 7046
ft3 and required volume was 6276 ft3). Therefore, the existing detention pond will have sufficient capacity
for the additional WQCV generated as a result of the proposed development.
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4.2.2 Detention Volume
In order to evaluate whether the existing pond would have sufficient capacity for the increased detention
volume requirements due to the proposed development, the 10-year and 100-year flow rates for the
existing basins (OS1, OS2, C1 and C2) were compared with the 10-year and 100-year flow rates for the
proposed basin (PR-1). The 10-year flow rates for the existing basins are 1.07 cfs for basin OS1, 0.85 cfs
for basin OS2, 0.96 cfs for basin C1 and 0.17 cfs for basin C2, with a total 10-year flow rate of 3.05 cfs.
The 100-year flow rates for the existing basins are 2.89 cfs for basin OS1, 1.85 cfs for basin OS2, 1.76 cfs
for basin C1 and 0.30 cfs for basin C2, with a total contributing 100-year flow rate of 6.80 cfs. As shown
in section 2.2, the 10-year flow rate for basin PR-1 is 3.13 cfs and the 100-year flow rate is 6.71 cfs. This
decrease in the 100-year flow rate compared with the Sopris Engineering calculations is the result of
reanalyzing the offsite basins using more up to date GIS contours. This analysis showed that basin OS1
was substantially smaller than what Sopris Engineering delineated. The additional area Sopris engineering
had included in this offsite basin should actually be part of basin OS8 which does not flow towards the
detention pond.
The storage volume for the existing detention pond was calculated using the modified FAA method which
uses the developed 10 and 100-year flow rates compared with the allowable release rates to calculate the
required detention volume. Since the changes in the 10-year flow rate is negligible and the 100-year flow
rate is decreased, the detention pond will continue to have sufficient detention volume for the proposed
site improvements.
4.2.3 Doolittle Pond
In order to evaluate the impact on Doolittle Pond as a result of the proposed development, the existing
and proposed 10 and 100-year flow rates for basin EX-2 (for existing) and PR-2 (for proposed) were
compared. The existing 10-year peak flow rate for basin EX-2 is is 8.85 cfs and the existing 100-year
peak flow rate is 21.99 cfs. The proposed 10-year peak flow rate for basin PR-2 is 8.14 cfs and the
proposed 100-year peak flow rate is 20.44 cfs. This decrease in the flow rate to Doolittle pond is the result
Existing Basin Water Quality Capture Volumes
Basin Total Area Impervious WQCV
(#)(acres)(%)(ft3)
OS1 1.80 3.00%131
OS2 0.70 24.00%140
C1 0.54 53.00%200
C2 0.08 63.00%35
Total 506
Water Quality Capture Volume Storage
Basin Total Area Impervious Area Impervious WQCV Table Value WQCV Storage F.O.S.Required Storage BMP
(#)(ft2)(ft2)(%)(in)(ft3)(ft3)
PR-1 124197.00 57131.00 46.00%0.089 921.13 1 921.1 Detention Pond Drywells
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of re-routing the parking lot inlet to the proposed AVH storm system. Since the impact of the proposed
development is to reduce the peak flow rate to Doolittle pond, no form of detention is needed.
A Contech CDS2015-5 unit will replace the existing street inlet in Doolittle Drive as a form of water
quality treatment for the portion of disturbed area flowing into Doolittle Pond. The unit was designed in
order to be able to treat the 2-year storm event for subbasin 2.1 (the contributing subbasin) equal to 0.46
cfs and in order to be able to safely pass the 100-year storm event of 1.57 cfs. A Contech CDS2015-5 has
a maximum treatment capacity of 0.7 cfs and a maximum bypass capacity of 10.0 cfs and is therefore
sufficiently sized for this application.
The outlet pipe for the Doolittle pond is located at the low point, therefore the pond does not have any
detention volume. The pond currently functions as a form of water quality treatment facility with a trickle
channel that is highly vegetated and acts to retard flows and promote sedimentation for lower intensity
events. With the reduction of flows to this pond, and the introduction of the CDS unit upstream, the water
quality treatment ability of this pond will be improved due to the proposed development.
5.0 Proposed Facilities
5.1 Proposed Inlets
Area drains around the ambulance facility will range in size from 8 to 18 inches. Grates used for 8” drain
basins will be 6” while all other drain basins will have grates matching the drainage basin size. These area
drains will be located at low points in either the landscaping or hardscaping around the site. The inlets
will capture runoff from the hillside immediately to the west of the facility as well as from some of the
landscaped and hardscaped areas surrounding the facility. An eight-inch trench drain will capture runoff
from a portion of the access drive on the north side of the facility. The remainder of runoff from the site
will be conveyed through curb and gutter to either the curb inlets located along Hospital Loop Road, the
parking lot loop and Doolittle Drive, or to the valley inlet in the parking lot. A 10’ CDOT Type R inlet
will capture all runoff from the offsite basin that is conveyed in the curb and gutter in HLR to the west of
the access drive. A CDOT Type R inlet is necessary in this location since the inlet is on-grade and all
runoff from the offsite basin must be collected before the snow-melted auto-court. The below table shows
the calculations for the capacity of the onsite area drains.
Sub Basin and Circular Inlet Calculations
1 Hour(P1)1.23 m=40%
Return Period 100 Cg=50%Co=0.65
Inlet ID Basin ID Q Max Inlet Type Diameter
Effective Open
Area(EQ. 4-20)Water Depth Inlet Capacity (EQ 4-19)Has Capacity
See(D1)ft3/sec Wo (inches)Ae=(1-Cg)mA Ys Q=CoAe√2gYs (Yes/No)
AADF INLET-1 1.1, 1.2 0.856 18" Round 18 0.353 0.350 1.090 Yes
AADF INLET-2 1.3 0.177 12" Round 12 0.157 0.100 0.259 Yes
AADF INLET-3 1.5 0.028 6" Round 6 0.039 0.042 0.042 Yes
AADF INLET-4 1.7 0.015 6" Round 6 0.039 0.042 0.042 Yes
Sub Basin and Rectangular Inlet Calculations
m=40%Ys=.05
Cg=50%Co=0.65
Inlet ID Basin ID Q Max Inlet Type Inlet Width Inlet Length Effective Open Area (EQ. 4-20)Inlet Capacity (EQ 4-19)Has Capacity
See(D1)(ft3/sec)Rectangular Wo (inches)Lo (inches)Ae=(1-Cg)mWoLo Q=CoAe√2gYs (Yes/No)
HLR Trench Drain 1 1.9 0.192 8" x 100'8 1200 13.333 15.552 Yes
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The valley and curb inlets were analyzed for capacity using UDFCD’s UD-Inlet spreadsheet. A
CDOT/Denver 13 Valley Grate was used for those inlets using Aspen’s standard grate with dimensions
corrected to match this grate type. These calculations can be found in Appendix-B.
5.2 Proposed Pipes
All proposed storm pipes were analyzed to ensure that they had sufficient capacity to convey the 100-year
storm event with the HGL at 80% of the pipes height. SDR35 PVC pipe will be used for the AADF and
parking lot storm system and reinforced concrete pipe will be used for the HLR storm system. The
calculations for these pipes can be found in the below tables.
100 Year Sub Basin Peak Discharge Developed Calculations
1 Hour(P1)1.23
Return Period 100
Sub Basin Total Area Imp. Area Impervious C Value Time of C Intensity Sub Basin Flow Rate
(Name)At (ft2)Ai (ft2)Ai/At (%)From Table (Td)I=88.8P1/(10+Td)01.052 Qsub (ft3/sec)
1.1 9665.31 0.00 0.00%0.500 12.21 4.19 0.464
1.2 2840.44 2840.44 100.00%0.950 5 6.33 0.392
1.3 2252.23 429.42 19.07%0.540 5 6.33 0.177
1.4 680.00 680.00 100.00%0.950 5 6.33 0.094
1.5 363.80 39.37 10.82%0.530 5 6.33 0.028
1.6 3707.78 3707.78 100.00%0.950 5 6.33 0.511
1.7 107.90 107.90 100.00%0.950 5 6.33 0.015
1.8 5786.64 2390.82 41.32%0.580 5 6.33 0.487
1.9 1788.92 1431.87 80.04%0.740 5 6.33 0.192
1.10 4203.64 3775.90 89.82%0.780 5 6.33 0.476
1.11 4411.73 4048.32 91.76%0.830 5 6.33 0.532
1.12 16762.85 16340.73 97.48%0.890 5 6.33 2.166
1.13 2851.92 1831.32 64.21%0.630 5 6.33 0.261
2.1 16975.02 13244.18 78.02%0.710 6.63 5.67 1.570
OS-1 68901.58 17136.85 24.87%0.550 13.27 3.99 3.467
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Storm System Pipes
Pipe System Pipe Contibuting Sub-Basins Design Flow Rate
Qdes
AADF PIPE-1 1.1-1.2 0.86
AADF PIPE-2 1.1-1.2 0.86
AADF PIPE-3 1.1-1.2 0.86
AADF PIPE-4 1.1-1.2 0.86
AADF PIPE-5 1.1-1.2 0.86
AADF PIPE-6 1.1-1.3 1.03
AADF PIPE-7 1.1-1.3 1.03
AADF PIPE-8 1.1-1.3 1.03
AADF PIPE-9 1.1-1.4 1.13
AADF PIPE-10 1.1-1.4 1.13
AADF PIPE-11 1.1-1.6 1.67
AADF PIPE-12 1.1-1.6 1.67
AADF PIPE-13 1.1-1.6 1.67
AADF PIPE-14 1.1-1.7 1.68
AADF PIPE-15 1.1-1.8 2.17
AADF PIPE-16 1.1-1.8 2.17
AADF PIPE-17 1.1-1.8 2.17
AADF PIPE-18 1.1-1.8 2.17
AADF PIPE-19 1.1-1.9 2.36
AADF PIPE-20 1.3 0.18
AADF PIPE-21 1.5 0.03
AADF PIPE-22 1.7 0.01
AADF PIPE-23 1.7 0.01
AADF PIPE-24 1.9 0.19
Crosswalk Pipe-1 1.8 0.49
Parking Lot PIPE-1 1.12 2.17
HLR PIPE-1 OS-1 3.47
HLR PIPE-2 OS-1, 1.1-1.10 6.30
HLR PIPE-3 OS-1, 1.1-1.11 6.84
HLR EX PIPE-1 OS-1, 1.1-1.11 6.84
HLR EX PIPE-2 OS-1, 1.1-1.12 9.26
Doolittle Doolittle Ex Pipe 2.1 1.57
AADF
HLR
Parking Lot
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5.3 Existing Storm System Analysis
The existing AVH storm system was analyzed in order to ensure that it had sufficient capacity to convey
the additional runoff. Basin’s OS1, OS2, C1 and C2 from the AVH master drainage plan were combined
into PR-1 (described in section 2.1) in order to analyze this system. The tables below summarize this
analysis. Sub-basin flow rates for all basins aside from PR-1 were taken from the AVH master drainage
plan.
Pipe Design Flow
Rate
Proposed Pipe
Diameter Slope 80% of Proposed
Pipe Diameter
Manning
Coefficient
Full Pipe Cross
Sectional Area Full Pipe Flow Rate Q Design /
Q Full d/D Hydraulic Grade Line
(Depth of Flow)
Depth of Flow Less Than
80% of Pipe Diameter
Qdes (ft3/sec) Dpro(in)S (%)Dpro*.8 (in)n A (ft) = π (Dpro/2)2 Qfull (ft3/s) = A(1.49/n)((Dpro/48)2/3)S1/2 Qdes/Qfull (from Chart)d (in) = (d/D)*Dpro (Yes/No)
AADF PIPE-1 0.86 6.0 2.00%4.8 0.01 0.196 1.034 0.83 0.77 4.59 Yes
AADF PIPE-2 0.86 6.0 2.00%4.8 0.01 0.196 1.034 0.83 0.77 4.59 Yes
AADF PIPE-3 0.86 6.0 19.89%4.8 0.01 0.196 3.260 0.26 0.38 2.28 Yes
AADF PIPE-4 0.86 6.0 2.00%4.8 0.01 0.196 1.034 0.83 0.77 4.59 Yes
AADF PIPE-5 0.86 6.0 8.00%4.8 0.01 0.196 2.068 0.41 0.50 3.00 Yes
AADF PIPE-6 1.03 6.0 8.00%4.8 0.01 0.196 2.068 0.50 0.55 3.30 Yes
AADF PIPE-7 1.03 6.0 46.42%4.8 0.01 0.196 4.981 0.21 0.35 2.10 Yes
AADF PIPE-8 1.03 10.0 1.00%8.0 0.01 0.545 2.855 0.36 0.47 4.70 Yes
AADF PIPE-9 1.13 10.0 1.00%8.0 0.01 0.545 2.855 0.39 0.49 4.85 Yes
AADF PIPE-10 1.13 10.0 1.00%8.0 0.01 0.545 2.855 0.39 0.49 4.85 Yes
AADF PIPE-11 1.67 10.0 1.00%8.0 0.01 0.545 2.855 0.58 0.62 6.15 Yes
AADF PIPE-12 1.67 10.0 1.00%8.0 0.01 0.545 2.855 0.58 0.62 6.15 Yes
AADF PIPE-13 1.67 10.0 1.00%8.0 0.01 0.545 2.855 0.58 0.62 6.15 Yes
AADF PIPE-14 1.68 10.0 1.00%8.0 0.01 0.545 2.855 0.59 0.62 6.15 Yes
AADF PIPE-15 2.17 10.0 1.00%8.0 0.01 0.545 2.855 0.76 0.73 7.25 Yes
AADF PIPE-16 2.17 10.0 1.00%8.0 0.01 0.545 2.855 0.76 0.73 7.25 Yes
AADF PIPE-17 2.17 10.0 1.00%8.0 0.01 0.545 2.855 0.76 0.73 7.25 Yes
AADF PIPE-18 2.17 10.0 5.00%8.0 0.01 0.545 6.383 0.34 0.45 4.50 Yes
AADF PIPE-19 2.36 10.0 5.00%8.0 0.01 0.545 6.383 0.37 0.47 4.70 Yes
AADF PIPE-20 0.18 4.0 2.00%3.2 0.01 0.087 0.351 0.50 0.57 2.28 Yes
AADF PIPE-21 0.03 4.0 2.00%3.2 0.01 0.087 0.351 0.08 0.22 0.88 Yes
AADF PIPE-22 0.01 4.0 4.00%3.2 0.01 0.087 0.496 0.03 0.12 0.48 Yes
AADF PIPE-23 0.01 4.0 4.00%3.2 0.01 0.087 0.496 0.03 0.12 0.48 Yes
AADF PIPE-24 0.19 4.0 6.87%3.2 0.01 0.087 0.650 0.30 0.41 1.62 Yes
Crosswalk Pipe-1 0.49 6.0 1.00%4.8 0.01 0.196 0.731 0.67 0.66 3.96 Yes
Parking Lot PIPE-1 2.17 8.0 4.62%6.4 0.01 0.349 3.384 0.64 0.65 5.16 Yes
HLR PIPE-1 3.47 15.0 2.00%12.0 0.013 1.227 9.155 0.38 0.49 7.28 Yes
HLR PIPE-2 6.30 15.0 2.00%12.0 0.013 1.227 9.155 0.69 0.68 10.13 Yes
HLR PIPE-3 6.84 15.0 2.00%12.0 0.013 1.227 9.155 0.75 0.70 10.54 Yes
HLR EX PIPE-1 6.84 15.0 5.55%12.0 0.013 1.227 15.251 0.45 0.52 7.73 Yes
HLR EX PIPE-2 9.26 15.0 5.06%12.0 0.013 1.227 14.563 0.64 0.65 9.68 Yes
Doolittle Ex Pipe 1.57 18.0 3.49%14.4 0.013 1.766 19.667 0.08 0.22 3.96 Yes
Hydraulic Grade Line and Pipe Capacity
06/26/2018
Aspen Ambulance District Facility 11
Drainage Report
Proposed 100 Year Sub Basin Peak Discharge
Sub Basin Total Area Total Area Imp. Area % Imp.C Value Time of C Sub Basin Flow Rate
(Name)At (acre)At (ft2)(ft2)From EX (Td)Qsub (ft3/sec)
PR-1 2.85 124197.00 57130.62 46.00%0.59 13.26 6.71
OS3 0.40 17424.00 13242.24 76.00%0.71 7.4 1.46
C3 0.28 12196.80 10123.34 83.00%0.76 5.3 1.22
C4 0.33 14374.80 10924.85 76.00%0.71 7.6 1.20
B1 1.02 44431.20 44431.20 100.00%0.95 5 5.59
B2 0.48 20908.80 12336.19 59.00%0.63 5 1.74
B3 0.51 22215.60 22215.60 100.00%0.95 5 2.80
B4 0.31 13503.60 11343.02 84.00%0.77 5 1.38
B5 0.39 16988.40 14270.26 84.00%0.77 6.5 1.62
B6 0.22 9583.20 9583.20 100.00%0.95 5 1.21
B7 0.45 19602.00 16857.72 86.00%0.79 5 2.06
D1 0.14 6098.40 2134.44 35.00%0.57 5 0.47
D2 0.27 11761.20 11761.20 100.00%0.95 5 1.48
D3 0.39 16988.40 4586.87 27.00%0.56 5.6 1.24
D4 0.33 14374.80 0.00 0.00%0.50 13.5 0.67
D5 0.32 13939.20 13939.20 100.00%0.95 5 1.76
D6 0.05 2178.00 152.46 7.00%0.52 5.8 0.15
D7 0.18 7840.80 7840.80 100.00%0.95 5 0.99
D8 0.12 5227.20 4756.75 91.00%0.84 5 0.58
E1 0.24 10454.40 8990.78 86.00%0.79 5 1.10
E2 0.25 10890.00 4464.90 41.00%0.58 7.6 0.74
J1 0.29 12632.40 0.00 0.00%0.50 5.8 0.81
Storm System Pipes
Pipe System Pipe Contibuting Sub-Basins Inlet Bypass Comments Design Flow Rate
Qdes
C2-C3 PR-1 0.2 Overflows to Doolittle Pond 6.71
C3-C4 PR-1, C3 0.02 Flows across Castle Creek Rd 7.93
C4-D1 PR-1, C3-C4 9.13
D1-D2 PR-1, B1-B7, C3-C4, D1 26.00
D2-D4 PR-1, B1-B7,C3-C4, D1, D2 27.48
D4-D7 PR-1, OS3, B1-B7, C3-C4, D1-D4 30.85
D7-D8 PR-1, OS3, B1-B7, C3-C4, D1-D7 0.02 Conveyed to Castle Creek ditch 33.75
D8-AE PR-1, OS3, B1-B7, C3-C4, D1-D8 0.02 Conveyed to Castle Creek ditch 34.33
A-E PR-1, OS3, B1-B7, C3-C4, D1-D8, E1, E2, J1 36.98
C
D
Pipe Design Flow
Rate
Proposed Pipe
Diameter Slope 80% of Proposed
Pipe Diameter
Manning
Coefficient
Full Pipe Cross
Sectional Area Full Pipe Flow Rate Q Design /
Q Full d/D Hydraulic Grade Line
(Depth of Flow)
Depth of Flow Less Than
80% of Pipe Diameter
Qdes (ft3/sec) Dpro(in)S (%)Dpro*.8 (in)n A (ft) = π (Dpro/2)2 Qfull (ft3/s) = A(1.49/n)((Dpro/48)2/3)S1/2 Qdes/Qfull (from Chart)d (in) = (d/D)*Dpro (Yes/No)
C2-C3 6.71 15.0 5.00%12.0 0.013 1.227 14.476 0.46 0.53 7.95 Yes
C3-C4 7.93 15.0 2.00%12.0 0.012 1.227 9.918 0.80 0.74 11.06 Yes
C4-D1 9.13 15.0 3.50%12.0 0.012 1.227 13.121 0.70 0.68 10.13 Yes
D1-D2 26.00 18.0 7.25%14.4 0.012 1.766 30.708 0.85 0.77 13.77 Yes
D2-D4 27.48 24.0 3.70%19.2 0.012 3.140 47.244 0.58 0.62 14.76 Yes
D4-D7 30.85 24.0 2.00%19.2 0.012 3.140 34.735 0.89 0.81 19.32 No
D7-D8 33.75 24.0 2.00%19.2 0.012 3.140 34.735 0.97 0.86 20.64 No
D8-AE 34.33 24.0 2.00%19.2 0.012 3.140 34.735 0.99 0.88 21.12 No
A-E 36.98 24.0 2.00%19.2 0.012 3.140 34.735 1.06 0.90 21.60 No
Hydraulic Grade Line and Pipe Capacity
06/26/2018
Aspen Ambulance District Facility 12
Drainage Report
This analysis showed that pipes D4-D7 through A-E exceeded 80% depth for the 100-year storm event;
however, they will continue to have capacity for the developed flows without surcharging the pipe.
Additionally, the flow rate to these pipes is slightly lower than they were designed for due to the decrease
to the 100-year flow rate of basin PR-1 as compared with basins OS1, OS2, C1 and C2. The pipes will
therefore function better than intended.
6.0 Operation and Maintenance
6.1 Parking Lot Deicing
As discussed with the City of Aspen, salt shall not be used as a method to deice the parking lot or any
portion of the site as all portions of the site flow into the existing Doolittle Pond or Aspen Valley Hospital
Detention Pond. Salt cannot realistically be removed from stormwater through conventional water quality
treatment methods. Therefore, the only method to avoid contaminating surface and groundwater with salt
is to avoid its use. An agreement to avoid the use of salt for deicing will be part of the maintenance plan
and has already been agreed to by Pitkin County Facility management.
The northeast corner of the parking lot will be the primary location used for snow storage. Additional
snow storage when needed will be located in Doolittle pond and in the landscaped areas surrounding the
parking lot.
6.2 Storm System Maintenance
A complete maintenance plan will be provided for the storm system prior to issuance of the Certificate of
Occupancy. Aspen Valley Hospital currently maintains the detention pond and Doolittle pond and will
continue to do so. Maintenance of the on-site storm system as well as the CDS unit in Doolittle drive will
be the responsibility of Pitkin County.
06/26/2018
Aspen Ambulance District Facility 13
Drainage Report
Appendix A – TOC Calculations
06/26/2018
Designer:
Company:
Date:
Project:
Location:
Subcatchment Name
EX-1 32
OVERLAND FLOW
Reach
ID
Overland Flow
Length
Li (ft)
Overland Flow
Slope
Si (ft/ft)
5-yr
Runoff
Coefficient, C5
Overland Flow
Time
ti (min)
OL-1 300.00 0.108 0.31 11.27
Weighted Totals 300.00 0.108 Total ti (min)11.27
CHANNELIZED FLOW
Reach
ID
Channelized Flow
Length
Lt (ft)
Channelized Flow
Slope
St (ft/ft)
NRCS
Conveyance
Factor K
Channelized Flow
Time
tt (min)
C-1 116.50 0.133 4.5 1.18
C-2 409.00 0.042 20 1.66
Weighted Totals 525.50 0.062 Total tt (min)2.85
Computed tc (min)14.11
Aspen, Colorado
Percent
Imperviousness
(%)
Reach-Weighted Time of Concentration Calculations
Version 2.00 released May 2017
SWW
RFE
4/2/2018
Aspen Ambulance Distric Facility (2017-44)
UD-RATIONAL 2.00 Offsite TOC.xlsm, Sub-EX-OS-1 Weighted Tc 4/2/2018, 9:43 PM06/26/2018
Designer:
Company:
Date:
Project:
Location:
Subcatchment Name
EX-2 26
OVERLAND FLOW
Reach
ID
Overland Flow
Length
Li (ft)
Overland Flow
Slope
Si (ft/ft)
5-yr
Runoff
Coefficient, C5
Overland Flow
Time
ti (min)
OL-1 300.00 0.357 0.28 7.88
Weighted Totals 300.00 0.357 Total ti (min)7.88
CHANNELIZED FLOW
Reach
ID
Channelized Flow
Length
Lt (ft)
Channelized Flow
Slope
St (ft/ft)
NRCS
Conveyance
Factor K
Channelized Flow
Time
tt (min)
C-1 885.00 0.129 4.5 9.13
C-2 272.00 0.066 20 0.88
C-3 401.00 0.085 4.5 5.09
C-4 129.00 0.078 20 0.38
Weighted Totals 1687.00 0.104 Total tt (min)15.49
Computed tc (min)23.37
Aspen, Colorado
Percent
Imperviousness
(%)
Reach-Weighted Time of Concentration Calculations
Version 2.00 released May 2017
SWW
RFE
4/2/2018
Aspen Ambulance Distric Facility (2017-44)
UD-RATIONAL 2.00 Offsite TOC.xlsm, Sub-EX-OS-2 Weighted Tc 4/2/2018, 9:44 PM06/26/2018
Designer:
Company:
Date:
Project:
Location:
Subcatchment Name
PR-1 46
OVERLAND FLOW
Reach
ID
Overland Flow
Length
Li (ft)
Overland Flow
Slope
Si (ft/ft)
5-yr
Runoff
Coefficient, C5
Overland Flow
Time
ti (min)
OL-1 300.00 0.108 0.37 10.41
Weighted Totals 300.00 0.108 Total ti (min)10.41
CHANNELIZED FLOW
Reach
ID
Channelized Flow
Length
Lt (ft)
Channelized Flow
Slope
St (ft/ft)
NRCS
Conveyance
Factor K
Channelized Flow
Time
tt (min)
C-1 116.50 0.133 4.5 1.18
C-2 409.00 0.042 20 1.66
Weighted Totals 525.50 0.062 Total tt (min)2.85
Computed tc (min)13.26
Aspen, Colorado
Percent
Imperviousness
(%)
Reach-Weighted Time of Concentration Calculations
Version 2.00 released May 2017
SWW
RFE
4/2/2018
Aspen Ambulance Distric Facility (2017-44)
UD-RATIONAL 2.00 Offsite TOC.xlsm, Sub-PR-OS-1 Weighted Tc 4/2/2018, 9:43 PM06/26/2018
Designer:
Company:
Date:
Project:
Location:
Subcatchment Name
PR-2 24
OVERLAND FLOW
Reach
ID
Overland Flow
Length
Li (ft)
Overland Flow
Slope
Si (ft/ft)
5-yr
Runoff
Coefficient, C5
Overland Flow
Time
ti (min)
OL-1 300.00 0.357 0.28 7.88
Weighted Totals 300.00 0.357 Total ti (min)7.88
CHANNELIZED FLOW
Reach
ID
Channelized Flow
Length
Lt (ft)
Channelized Flow
Slope
St (ft/ft)
NRCS
Conveyance
Factor K
Channelized Flow
Time
tt (min)
C-1 885.00 0.129 4.5 9.13
C-2 272.00 0.066 20 0.88
C-3 401.00 0.085 4.5 5.09
C-4 129.00 0.078 20 0.38
Weighted Totals 1687.00 0.104 Total tt (min)15.49
Computed tc (min)23.37
Aspen, Colorado
Percent
Imperviousness
(%)
Reach-Weighted Time of Concentration Calculations
Version 2.00 released May 2017
SWW
RFE
4/2/2018
Aspen Ambulance Distric Facility (2017-44)
UD-RATIONAL 2.00 Offsite TOC.xlsm, Sub-PR-OS-2 Weighted Tc 4/2/2018, 9:44 PM06/26/2018
Designer:
Company:
Date:
Project:
Location:
Subcatchment Name
1.1 0
OVERLAND FLOW
Reach
ID
Overland Flow
Length
Li (ft)
Overland Flow
Slope
Si (ft/ft)
5-yr
Runoff
Coefficient, C5
Overland Flow
Time
ti (min)
1 158.79 0.147 0.15 8.90
Weighted Totals 158.79 0.147 Total ti (min)8.90
CHANNELIZED FLOW
Reach
ID
Channelized Flow
Length
Lt (ft)
Channelized Flow
Slope
St (ft/ft)
NRCS
Conveyance
Factor K
Channelized Flow
Time
tt (min)
1 116.50 0.022 4.5 2.91
Weighted Totals 226.90 0.038 Total tt (min)3.30
Computed tc (min)12.21
Aspen, Colorado
Percent
Imperviousness
(%)
Reach-Weighted Time of Concentration Calculations
Version 2.00 released May 2017
SWW
RFE
4/2/2018
AADF (2017-44)
UD-RATIONAL 2.00 TOC.xlsm, Sub-1.1 Weighted Tc 4/2/2018, 9:45 PM06/26/2018
Designer:
Company:
Date:
Project:
Location:
Subcatchment Name
2.1 84.34
OVERLAND FLOW
Reach
ID
Overland Flow
Length
Li (ft)
Overland Flow
Slope
Si (ft/ft)
5-yr
Runoff
Coefficient, C5
Overland Flow
Time
ti (min)
1 114.00 0.030 0.68 5.63
Weighted Totals 114.00 0.030 Total ti (min)5.63
CHANNELIZED FLOW
Reach
ID
Channelized Flow
Length
Lt (ft)
Channelized Flow
Slope
St (ft/ft)
NRCS
Conveyance
Factor K
Channelized Flow
Time
tt (min)
1 238.00 0.040 20 0.99
Weighted Totals 238.00 0.040 Total tt (min)0.99
Computed tc (min)6.63
Aspen, Colorado
Percent
Imperviousness
(%)
Reach-Weighted Time of Concentration Calculations
Version 2.00 released May 2017
SWW
RFE
4/2/2018
AADF (2017-44)
UD-RATIONAL 2.00 TOC.xlsm, Sub-2.1 Weighted Tc 4/2/2018, 9:46 PM06/26/2018
Designer:
Company:
Date:
Project:
Location:
Subcatchment Name
OS-1 25
OVERLAND FLOW
Reach
ID
Overland Flow
Length
Li (ft)
Overland Flow
Slope
Si (ft/ft)
5-yr
Runoff
Coefficient, C5
Overland Flow
Time
ti (min)
1 300.00 0.108 0.28 11.69
Weighted Totals 300.00 0.108 Total ti (min)11.69
CHANNELIZED FLOW
Reach
ID
Channelized Flow
Length
Lt (ft)
Channelized Flow
Slope
St (ft/ft)
NRCS
Conveyance
Factor K
Channelized Flow
Time
tt (min)
1 116.50 0.133 4.5 1.18
2 110.40 0.054 20 0.40
Weighted Totals 226.90 0.095 Total tt (min)1.58
Computed tc (min)13.27
Aspen, Colorado
Percent
Imperviousness
(%)
Reach-Weighted Time of Concentration Calculations
Version 2.00 released May 2017
SWW
RFE
4/2/2018
AADF (2017-44)
UD-RATIONAL 2.00 TOC.xlsm, Sub-OS-1 Weighted Tc 4/2/2018, 9:45 PM06/26/2018
Aspen Ambulance District Facility 14
Drainage Report
Appendix B – Inlet Calculations
06/26/2018
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =0.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.013
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =12.0 ft
Gutter Width W =2.00 ft
Street Transverse Slope SX =0.020 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.035 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.016
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =6.0 12.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no)check = yes
MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow =2.2 8.8 cfs
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Version 4.05 Released March 2017
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Aspen Ambulance District Facility
HLR Inlet 1
UD-Inlet_v4.05.xlsm, HLR INLET 1 5/7/2018, 3:43 PM06/26/2018
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a')aLOCAL =3.0 3.0 inches
Total Number of Units in the Inlet (Grate or Curb Opening)No =2 2
Length of a Single Unit Inlet (Grate or Curb Opening)Lo =5.00 5.00 ft
Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo =N/A N/A ft
Clogging Factor for a Single Unit Grate (typical min. value = 0.5)Cf-G =N/A N/A
Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1)Cf-C =0.12 0.12
Street Hydraulics: OK - Q < Allowable Street Capacity'MINOR MAJOR
Total Inlet Interception Capacity Q =1.38 3.47 cfs
Total Inlet Carry-Over Flow (flow bypassing inlet)Qb =0.00 0.00 cfs
Capture Percentage = Qa/Qo =C% =100 100 %
INLET ON A CONTINUOUS GRADE
Version 4.05 Released March 2017
CDOT Type R Curb OpeningCDOT Type R Curb Opening
UD-Inlet_v4.05.xlsm, HLR INLET 1 5/7/2018, 3:43 PM06/26/2018
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =0.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.013
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =12.0 ft
Gutter Width W =2.00 ft
Street Transverse Slope SX =0.010 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.022 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.016
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =6.0 12.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no)check = yes
MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Spread Criterion Qallow =1.0 2.8 cfs
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Version 4.05 Released March 2017
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Aspen Ambulance District Facility
HLR Inlet 2
UD-Inlet_v4.05.xlsm, HLR Inlet 2 5/7/2018, 3:44 PM06/26/2018
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a')aLOCAL =2.0 2.0 inches
Total Number of Units in the Inlet (Grate or Curb Opening)No =1 1
Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening)Lo =2.46 2.46 ft
Warning 1 Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo =1.37 1.37 ft
Clogging Factor for a Single Unit Grate (typical min. value = 0.5)Cf-G =0.50 0.50
Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1)Cf-C =N/A N/A
Street Hydraulics: OK - Q < Allowable Street Capacity'MINOR MAJOR
Total Inlet Interception Capacity Q =0.22 0.34 cfs
Total Inlet Carry-Over Flow (flow bypassing inlet)Qb =0.05 0.13 cfs
Capture Percentage = Qa/Qo =C% =80 73 %
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
INLET ON A CONTINUOUS GRADE
Version 4.05 Released March 2017
CDOT/Denver 13 Valley GrateCDOT/Denver 13 Valley Grate
UD-Inlet_v4.05.xlsm, HLR Inlet 2 5/7/2018, 3:44 PM06/26/2018
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =8.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.013
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =12.0 ft
Gutter Width W =2.00 ft
Street Transverse Slope SX =0.070 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.049 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.016
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =6.0 12.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no)check = yes
MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =7.9 7.9 cfs
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Version 4.05 Released March 2017
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Aspen Ambulance District Facility
HLR Inlet 3
UD-Inlet_v4.05.xlsm, HLR Inlet 3 5/7/2018, 3:44 PM06/26/2018
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a')aLOCAL =2.0 2.0 inches
Total Number of Units in the Inlet (Grate or Curb Opening)No =2 2
Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening)Lo =2.46 2.46 ft
Warning 1 Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo =1.37 1.37 ft
Clogging Factor for a Single Unit Grate (typical min. value = 0.5)Cf-G =0.50 0.50
Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1)Cf-C =N/A N/A
Street Hydraulics: OK - Q < Allowable Street Capacity'MINOR MAJOR
Total Inlet Interception Capacity Q =0.28 0.47 cfs
Total Inlet Carry-Over Flow (flow bypassing inlet)Qb =0.08 0.19 cfs
Capture Percentage = Qa/Qo =C% =79 71 %
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
INLET ON A CONTINUOUS GRADE
Version 4.05 Released March 2017
CDOT/Denver 13 Valley GrateCDOT/Denver 13 Valley Grate
UD-Inlet_v4.05.xlsm, HLR Inlet 3 5/7/2018, 3:44 PM06/26/2018
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =0.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =20.0 ft
Warning 1 Gutter Width W =2.00 ft
Street Transverse Slope SX =0.040 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.042 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.016
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =10.0 20.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Check boxes are not applicable in SUMP conditions
MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs
Version 4.05 Released March 2017
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Aspen Ambulance District Facility
Crosswalk Inlet
UD-Inlet_v4.05.xlsm, Crosswalk Inlet 5/7/2018, 3:46 PM06/26/2018
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from above)alocal =2.00 2.00 inches
Number of Unit Inlets (Grate or Curb Opening)No =1 1
Water Depth at Flowline (outside of local depression)Ponding Depth =4.8 6.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) =2.46 2.46 feet
Warning 1 Width of a Unit Grate Wo =1.37 1.37 feet
Area Opening Ratio for a Grate (typical values 0.15-0.90)Aratio =0.43 0.43
Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =0.50 0.50
Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =3.30 3.30
Warning 4 Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =0.65 0.65
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) =N/A N/A feet
Height of Vertical Curb Opening in Inches Hvert =N/A N/A inches
Height of Curb Orifice Throat in Inches Hthroat =N/A N/A inches
Angle of Throat (see USDCM Figure ST-5)Theta =N/A N/A degrees
Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =N/A N/A feet
Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =N/A N/A
Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =N/A N/A
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =N/A N/A
Low Head Performance Reduction (Calculated)MINOR MAJOR
Depth for Grate Midwidth dGrate =0.484 0.581 ft
Depth for Curb Opening Weir Equation dCurb =N/A N/A ft
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination =N/A N/A
Curb Opening Performance Reduction Factor for Long Inlets RFCurb =N/A N/A
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate =0.80 1.00
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition)Qa =1.6 2.6 cfs
Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.2 0.5 cfs
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
Warning 4: Weir or orifice coefficient is not the recommended value for the inlet type specified.
CDOT/Denver 13 Valley Grate
INLET IN A SUMP OR SAG LOCATION
Version 4.05 Released March 2017
H-VertH-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT/Denver 13 Valley Grate
Override Depths
UD-Inlet_v4.05.xlsm, Crosswalk Inlet 5/7/2018, 3:46 PM06/26/2018
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =0.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =24.0 ft
Gutter Width W =2.00 ft
Street Transverse Slope SX =0.015 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.016
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =6.0 10.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Check boxes are not applicable in SUMP conditions
MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs
Version 4.05 Released March 2017
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Aspen Ambulance District Facility
Parking Lot Inlet
UD-Inlet_v4.05.xlsm, Parking Lot Inlet 5/7/2018, 3:45 PM06/26/2018
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from above)alocal =2.00 2.00 inches
Number of Unit Inlets (Grate or Curb Opening)No =1 1
Water Depth at Flowline (outside of local depression)Ponding Depth =6.0 6.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) =3.00 3.00 feet
Width of a Unit Grate Wo =1.73 1.73 feet
Area Opening Ratio for a Grate (typical values 0.15-0.90)Aratio =0.43 0.43
Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =0.50 0.50
Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =3.30 3.30
Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =0.60 0.60
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) =N/A N/A feet
Height of Vertical Curb Opening in Inches Hvert =N/A N/A inches
Height of Curb Orifice Throat in Inches Hthroat =N/A N/A inches
Angle of Throat (see USDCM Figure ST-5)Theta =N/A N/A degrees
Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =N/A N/A feet
Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =N/A N/A
Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =N/A N/A
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =N/A N/A
Low Head Performance Reduction (Calculated)MINOR MAJOR
Depth for Grate Midwidth dGrate =0.523 0.523 ft
Depth for Curb Opening Weir Equation dCurb =N/A N/A ft
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination =N/A N/A
Curb Opening Performance Reduction Factor for Long Inlets RFCurb =N/A N/A
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate =0.94 0.94
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition)Qa =2.6 2.6 cfs
Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =1.3 2.2 cfs
CDOT/Denver 13 Valley Grate
INLET IN A SUMP OR SAG LOCATION
Version 4.05 Released March 2017
H-VertH-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT/Denver 13 Valley Grate
Override Depths
UD-Inlet_v4.05.xlsm, Parking Lot Inlet 5/7/2018, 3:45 PM06/26/2018
Project:
Inlet ID:
Gutter Geometry (Enter data in the blue cells)
Maximum Allowable Width for Spread Behind Curb TBACK =3.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.013
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =12.0 ft
Gutter Width W =2.00 ft
Street Transverse Slope SX =0.027 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.054 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.016
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =6.0 12.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches
Allow Flow Depth at Street Crown (leave blank for no)check = yes
MINOR STORM Allowable Capacity is based on Spread Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =3.6 12.2 cfs
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Version 4.05 Released March 2017
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Aspen Ambulance District Facility
HLR EX Inlet
UD-Inlet_v4.05.xlsm, HLR EX Inlet 5/7/2018, 3:43 PM06/26/2018
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a')aLOCAL =2.0 2.0 inches
Total Number of Units in the Inlet (Grate or Curb Opening)No =2 2
Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening)Lo =2.46 2.46 ft
Warning 1 Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo =1.37 1.37 ft
Clogging Factor for a Single Unit Grate (typical min. value = 0.5)Cf-G =0.50 0.50
Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1)Cf-C =0.10 0.10
Street Hydraulics: OK - Q < Allowable Street Capacity'MINOR MAJOR
Total Inlet Interception Capacity Q =0.24 0.55 cfs
Total Inlet Carry-Over Flow (flow bypassing inlet)Qb =0.05 0.16 cfs
Capture Percentage = Qa/Qo =C% =81 77 %
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
INLET ON A CONTINUOUS GRADE
Version 4.05 Released March 2017
CDOT/Denver 13 CombinationCDOT/Denver 13 Combination
UD-Inlet_v4.05.xlsm, HLR EX Inlet 5/7/2018, 3:43 PM06/26/2018
Aspen Ambulance District Facility 15
Drainage Report
Appendix C – Swale Capacity Calculations
06/26/2018
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Friday, May 4 2018
<Name>
Triangular
Side Slopes (z:1) = 10.00, 6.90
Total Depth (ft) = 0.50
Invert Elev (ft) = 8029.00
Slope (%) = 2.00
N-Value = 0.030
Calculations
Compute by: Known Q
Known Q (cfs) = 0.86
Highlighted
Depth (ft) = 0.25
Q (cfs) = 0.860
Area (sqft) = 0.53
Velocity (ft/s) = 1.63
Wetted Perim (ft) = 4.26
Crit Depth, Yc (ft) = 0.24
Top Width (ft) = 4.23
EGL (ft) = 0.29
0 1 2 3 4 5 6 7 8 9 10 11
Elev (ft)Depth (ft)Section
8028.75 -0.25
8029.00 0.00
8029.25 0.25
8029.50 0.50
8029.75 0.75
8030.00 1.00
Reach (ft)
06/26/2018