HomeMy WebLinkAboutDrainage Reports - 09/10/1997 (2)l
;Final rd ReDort
D�¢e
SHEAR
ENGINEERING
CORPORATIGN
Final Drainage and Erosion Control Report
for
VANWORKS SUBDIVISION SECOND FILING
Fort Collins, Colorado
�L
SEP - 31997
Prepared for:
Vanworks, Inc.
900 East Lincoln Avenue
Fort Collins, Colorado 80524
Y Prepared b P Y:
Shear Engineering Corporation
Project No: 1409-03-96
Date: August, 1997
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4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226.5334 FAX (970) 282.031 1
No Text
April 18, 1997
Project No: 1409-03-96
Basil Hamdan
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: Vanworks Subdivision Second Filing; Fort Collins, Colorado
Dear Basil,
Enclosed, please find the Final Drainage and Erosion Control Report for Vanworks Subdivision
Second Filing. The hydrology data and the hydraulic analysis presented in this report complies
with the requirements of the City of Fort Collins Storm Drainage Criteria Manual; dated March
1984, and the Erosion Control Reference Manual.
All Stormwater Utility comments by Matt Fater dated March 28, 199 have been addressed as
follows;
Written comments
1 The proposed grading at the northeast corner of the. proposed addition to the Phelps
Tointon building has been revised to allow for the Phelps-Tointon site to drain into the
pond. `
2 An offsite grading easement wiil;be.provided. The owner of Lot 1 also owns Lot 2 and
is working with us with regards to easements.
3 Grading of the outfall swale is now shown. Erosion control measures are shown at the
outfall of the pipe. The area will be seeded in accordance with the seeding notes on the
drainage and erosion control plan.
4 We understand that a Floodplain use permit is required and have informed Vanworks
Inc. of this requirement.
5 The outlet pipe diameter has been increased to a 15" ADS with slope of 0.004 ft/ft. The
capacity of the pipe is 4.42 cfs, greater than the release rate of 3.71 cfs. Therefore
pressure flow is no longer a concern.
6 An 8" orifice is still shown on the plans and in the report as the restricting device for the
outlet structure. We have used an 8" orifice instead of a 9 1/4" orifice because it can be
installed by putting a piece of 8" PVC into the forms of the outlet.box prior to pouring. It
also restricts the release rate to less than required. This in our opinion will make the
construction easier and improves the hydrology by reducing the flow from the site.
Report
Page 6
* The required 100-year W.S.EI. refers to the elevation calculated from the stage storage
curve at which the volume requirement is met. This indicates that the release at this
elevation is less than the allowable release rate. Therefore the volume requirement is met.
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-031 1
April 18, 1997
Page 2
Project No: 1409-03-96
Plans
Sheet 2
* The sanitary sewer is now shown in the plan view.
Sheet 5
* Curb and gutter in parking areas are not required and will not be provided.
* The 44 contour is now connected to the proper contour.
* The Finished Floor Elevation is now labeled on the future building addition on Lot 1, the
Second Replat of the North Lemay Subdivision.
* Flows from Buckingham Street will not enter into the site. We are matching what was built
with the Phelps-Tointon site to the east. The detached sidewalk will be higher than the
curb and gutter. This prevents the water from entering the site. The pond has been sized
with the 1/2 ROW area included in the calculations.
Sheet 6
* A detail of the type 2 outlet structure is shown on sheet 7. A construction detail is provided
on the detail sheet.
* The C factor for sub -basin A is now 0.48 on the plan and in the flow summary.
* Riprap is provided on the plan and profile of the outlet and the Swale ( Sheet 7).;Ls
* The flow path for historic and developed conditions is not seriously affected by the
development since the grade of the site will remain essentially the same except where the
pond is deepened slightly. It is our opinion that the time of concentration for both existing
and developed condition is essentially the same.
Sheet 7
* Proposed contours which reflect the final grading of the offsite Swale have now been
provided on the grading plan.
If you have any questions or comments, please call Mark Oberschmidt or me at 226-5334.
Sincerely,
Brian W. Shear, P.E.
Shear Engineering Corporation
BWS / meo
cc: Keith Hess; Vanworks, Inc.
Bryan Tointon;_Phelps-Tointon
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March 4, 1997
Project No: 1409-03-96
Basil Hamdan
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: Vanworks Subdivision Second Filing; Fort Collins, Colorado
Dear Basil,
Enclosed, please find the Final Drainage and Erosion Control Report for Vanworks Subdivision
Second Filing. The hydrology data and the hydraulic analysis presented in this report complies with
the requirements of the City of Fort Collins Storm Drainage Criteria Manual; dated March 1984,
and the Erosion Control Reference Manual.
Please note that this report also serves as an amendment to the approved Storm Drainage Report for
Lot 1, Second Replat of the North Lemay Subdivision, Second Filing prepared by Stewart and
Associates, Inc. The reason for the amendment is that Phelps-Tointon, Inc., the owners of Lot 1,
plan to construct an addition to the existing building on Lot 1 in the near future. Therefore we have
considered this future addition in the redesign of the detention pond on the Phelps-Tointon site.
All Stormwater.Utility . comments. by Matt Fater dated October .l8,-:1996 have been addressed -as
follows;
1. The proposed pond on the Phelps-Tointon site has received -approval from the owners of the
Phelps-Tointon property. All necessary easement descriptions and dedication language are
included with this submittal.
2: A plan and profile of the outfall pipe and swale from the detention pond are now included in
the plan set. An additional 10' Drainage Easement is now shown on Lot 2 of the Second
Replat of the North Lemay Subdivision, Second Filing. This was necessary because of the
location of the sanitary sewer for the K-Venture Property in the existing 20' Utility Easement
along the southern property line of Lot 2.
3. A cross section of the outfall swale is shown on the plan and profile sheet. Grading is also
shown.
4. An exhibit representing the limits of the 160-year floodplain is included in this report and
shown on the plan. The proposed building on the Vanworks site is located outside of the
100-year floodplain.
5. A detailed cross section and plan view of the emergency overflow structure has been added
to the drainage and erosion control plan.
We have modified the planned detention pond on the Phelps-Tointon site to accommodate future
expansion of the Phelps-Tointon Building according to data provided by Bryan Tointon. This has
included regrading the swale along the west side of North Lemay Avenue and west into Lot 2,
Second Replat of the North Lemay Subdivision, Second Filing. The existing outlet structure from
the pond will be replaced with a Type 2 outlet structure. The outlet pipe from the detention pond
will extend beyond the existing sanitary sewer line which services the K-Venture property to the
southeast.
PAGE 2
March 4, 1997
Project No: 1409-03-96
Re: Vanworks Subdivision Second Filing; Fort Collins, Colorado
If you have any questions or comments, please call Mark Oberschmidt or me at 226-5334.
Sincerely,
Brian W. Shear, P.E.
Shear Engineering Corporation
BWS / meo
cc: Keith Hess; Vanworks, Inc.
Bryan Tointon; Phelps-Tointon
September 16, 1996
Project No: 1409-03-96
Basil Hamdan
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: Vanworks Subdivision Second Filing; Fort Collins, Colorado
Dear Basil,
Enclosed, please find the Final Drainage and Erosion Control Report for Vanworks Subdivision
Second Filing. The hydrology data and the hydraulic analysis presented in this report complies with
the requirements of the City of Fort Collins Storm Drainage Criteria Manual; dated March 1984,
and the Erosion Control Reference Manual.
If you have any questions or comments, please call Mark Oberschmidt or me at 226-5334.
Brian W. Shear, P.E.
Shear Engineering Corporation.
BWS / meo
cc: Keith Hess; Vanworks, Inc.
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-0311
Page 1
Final Drainage and Erosion Control Report
Project No: 1409-03-96
L GENERAL LOCATION AND DESCRIPTION:
A. Location
1. Vanworks Subdivision Second Filing is located in the Northeast 1/4 of Section 12, UN,
R69W of the 6th P.M., Fort Collins, Colorado. The Project will consist of the replat of
lot 11 and Lots 20-23 of the Replat of the North Lemay Subdivision, Second Filing and a
portion of the Vanworks Minor Subdivision.
2. More specifically, the site is located at 900 East Lincoln Avenue. It is located in the
Northeast section of Old Town Fort Collins near the Poudre River.
3. The site is bounded on the south by East Lincoln Avenue, on the west by Patrick
Subdivision First Filing and unplatted property, on the north by Buckingham Street and
on the east by The Second Replat of the North Lemay Subdivision Second Filing, the
Replat of the North Lemay Subdivision and the North Lemay Subdivision First Filing.
B. Description of Property
1. The project consists of the expansion of the Vanworks facility which will include the
addition of a 100'x200' steel building and a parking lot to facilitate employee parking.
This project and drainage analysis considers the North portion of the Vanworks facility
only.
2. Total site area under consideration is 411,055 square feet or 9.44 acres, more or less.
3. There are existing utilities which will service the site. They are located in East Lincoln
Street, Buckingham Street and within the site.
4. Development will only occur on the. portion of the Vanworks site defined by the
Vanworks Subdivision Second Filing. Development of the site will consist of the
following;
a. Construction of a new 20,000 square foot building (100'x200') in the northern portion
of the site and a . paved parking area to facilitate employee parking west of the
proposed building site.
b. The building will be used as a paint and body shop.
c. Reconstruction of the Phelps-Tointon (Lot 1, Second Replat of the North Lemay
Subdivision, Second Filing) detention pond and the downstream drainage channel
along the south Lot 2, Second Replat of the North Lemay Subdivision, Second Filing
property line between the Phelps-Tointon detention pond and the Lemay Avenue
drainage channel.
5. A fire lane will be provided along the eastern property line in accordance with City
requirements. This fire lane will connect East Lincoln Street with Buckingham Street
through the Vanworks site.
Page 2
Final Drainage and Erosion Control Report
Project No: 1409-03-96
H. DRAINAGE BASINS AND SUB -BASINS:
A. Major Basin Description
1. The site is located within the Poudre River Basin as defined on the City of Fort Collins
Master Stormwater Basin Map.
a. There ismo=Basin Rate fee for the Poudre River Basin according to the development
fee section of the City of Fort Collins Development Manual.
2. The flow pattern of this portion of Old Town Basin is generally easterly and southerly to
the Cache La Poudre River. It is highly channelized as it is almost completely developed
in this area. Street and roadside ditches are the primary means of stormwater conveyance
at this time.
3. It is our understanding, that there is no Master Drainage Plan presently in place for this
area.
4. There are no irrigation facilities located on site or within.100' of the site. .
5. The portion of the site being developed is not in the 100-year flood plain as delineated on
the Flood Insurance Rate Map (FIRM) for the City of Fort Collins, Community Panel
Number 080102-0004-C; dated March 18, 1996. Refer to the floodplain exhibit in
Appendix III of this report "
6. According to the FIRM, the portion of the site where the proposed building is to be
constructed is situated in Zone X which is defined as areas of the 500-year flood or areas
of the 100-year flood with average depths less than 1.0 foot
7. The property to the south where the existing buildings are located, is in the 100-year
floodplain. The FIRM represents a Base Flood Elevation (BFE) in this area of between
4942 and 4943 feet.
8. The southern portion of Lot 1 of the Second Replat of the North Lemay Subdivision
(Phelps-Tointon Manufacturing), is also situated in the 100-year floodplain with a BFE of
between 4941 and 4942 feet.
9. The southern portion of Lot 2 of the Second Replat of the North Lemay Subdivision is
also situated in the 100-year floodplain with a BFE of between 4940 and 4941 feet. The
existing Phelps-Tointon Building is not within the current 100-year floodplain.
B. Sub -Basin Description
1. Runoff from the portion of the Vanworks site to be developed, flows predominately to
the east into the existing detention pond located on Lot 1 of the Second Replat of the
North Lemay Subdivision (Phelps-Tointon Manufacturing), then via channel flows to
North Lemay Avenue and South to the Poudre River.
2. The site is extremely flat. The slope of the land is generally less than 1.0%.
Page 3
Final Drainage and Erosion Control Report
Project No: 1409-03-96
M. DRAINAGE DESIGN CRITERIA:
A. Regulations
1. This final report and the final Grading, Drainage and Erosion Control Plans for Vanworks
Subdivision Second Filing were prepared in accordance with the requirements of the
current City of Fort Collins Storm Drainage Design Criteria and Erosion Control Criteria.
Suggestions by City of Fort Collins Stormwater Utility personnel were also considered.
B. Development Criteria Reference and Constraints
1. Buckingham Street will ultimately be widened to collector standards with detached
sidewalk. This work is to be completed in the future by others.
Detention is required in the Poudre River Basin. There is an existing detention basin to
the east that was constructed with the development of the Phelps-Tointon property. We
have received approval from the owners of the Phelps-Tointon property to utilize the
detention pond to accommodate additional runoff from this portion of the Vanworks site.
In addition to this, we have been informed by Phelps-Tointon that a 2400 sf addition is
planned for the Phelps-Tointon site.
a. The existing Phelps-Tointon detention pond drainage easement will be vacated.
b. The new drainage easement will replace the existing drainage easement that is shown
on Lot 1 of the Final Plat of the Second Replat of North Lemay Subdivision, Second
Filing.
3. The proposed grading in the area where the new building will be constructed will
maintain the existing flow path onto the Phelps-Tointon site in order to make use of the
existing detention pond.
4. The site is bounded on the east and west by developed sites. All grading along the east
and west property lines will match the existing conditions.
a. The only exception to this will occur in the areas where grading is done to increase
the capacity of the detention pond on the Phelps-Tointon site.
5. The future addition on the Phelps-Tointon property will have the same finished floor
elevation of the existing building.
6. There is a mini -storage facility on the lot south of the Phelps-Tointon property. A fence
has been constructed along the common property line. All grading along this common
property line will match the existing grades at the fence line.
7. The pond is sized using the total area of the site and the 1/2 ROW of Buckingham site
(14.76 acres). City Stormwater requires that the historic 2-year peak flow be used as the
release rate from the pond. Due to site and street topography, it is not feasible to get all of
the runoff from Buckingham Street into the site. Therefore the release rate has been
reduced by the amount that bypasses the site.
Page 4
Final Drainage and Erosion Control Report
Project No: 1409-03-96
III. DRAINAGE DESIGN CRITERIA:
C. Hydrological Criteria
1. The detention pond volume requirements were established restricting the release from the
pond to the historic 2-year peak flow. Historic conditions were defined as;
a. Existing conditions on the portion of the Vanworks site to be developed.
b. Pre -developed conditions on the Phelps-Tointon site.
2. Developed conditions included the future addition on the Phelps-Tointon property.
3. The Rainfall -Intensity -Duration curves for the City of Fort Collins were used (Figure 3-1,
attached for reference), in conjunction with the 'Rational Method" for determining peak
flows to the detention pond.
4. Detention pond volumes were determined using the Mass Diagram Method (Cumulative
Runoff Method). In order to divert as much water to the pond from Buckingham a 4 foot
sidewalk culvert will be installed at the northeast corner of the site. Due to the site
topography it is not possible to get all of the water from Buckingham to the pond.
Approximately 1.34 cfs bypasses the sidewalk culvert. Therefore we have reduced the
release rate from the pond from.3.71 cfs to 2.37 cfs. Refer.to pages 3. and 3A in the
drainage calculations.
D. Hydraulic Criteria
1. Drainage channel capacities were based on the Mannings Equation. The Mannings
coefficients are as suggested by the City of Fort Collins Storm Drainage Criteria Manual.
IV. DRAINAGE FACILITY DESIGN:
A. General Concept
1. Runoff is conveyed to the detention pond located on the Phelps-Tointon site primarily by
overland flow.
2. Expansion of the existing detention pond on Lot 1, Second Replat of the North Lemay
Subdivision is required to detain the additional developed flows from the northern portion
of the Vanworks site.
Page 5
Final Drainage and Erosion Control Report
Project No: 1409-03-96
IV. DRAINAGE FACILITY DESIGN:
B. Specific Details
1. The existing detention pond on the Phelps-Tointon site was designed by Stewart and
Associates in conjunction with the plans for the existing building on the site only.
a. The original required storage capacity was 32,298 cubic feet according to the
drainage plan and report for the Phelps-Tointon site. Apparently, no freeboard was
considered or required.
b. The pond currently has 36,689 cubic feet of available storage capacity. This is based
on an as -built survey performed by Intermill Land Surveying on August 2, 1996 in
association with Vanworks Subdivision Second Filing.
2. The top of the berm along the southern and eastern property line is to be raisedto an
elevation of 4942.0 feet. The bottom of the pond is to be regraded as well. Refer to the
Grading plan for more information. These modifications to the existing pond will be
provided in order to achieve the additional detention volumes required due to increased
flows from the Vanworks expansion and the addition proposed to the Phelps-Tointon
building.
3. The following table summarizes the proposed design and as built information for the
detention pond on the Phelps-Tointon property.
Existing Pond Proposed Pond
Bottom of Pond elevation
4939.85 feet
4938.92 feet
Top of Berm elevation
4941.60 feet
4942.0 feet
Detention Volume Provided
0.84 ac-ft
1.88 ac-ft
36,689 cf.
81,859 cf.
Detention Volume Required
0.74 ac-ft
1.76 ac-ft
32,298 cf.
76,630 cf.
Required 100 -year W. S. Elev. in pond
4941.35 feet
4941.91 feet
Actual 100 year W. S. Elev.
4941.35 feet
4941.94 feet
Total Contributing Area to Pond
7.46 acres
14.76 acres
Maximum Allowable
100 year release rate (Historic Q2)
2.04 cfs
2.37 cfs
A
M
t4:
Page 6
Final Drainage and Erosion Control Report
Project No: 1409-03-96
IV. DRAINAGE FACILITY DESIGN:
B. Specific Details
4. The following table summarizes the stage -storage relationship of the expanded pond
Storage
Storage
Stage ft.
Volume cf.)
Volume (ac-ft)
0
0
0.00
0.25
149
0.00
1.25
23,269
0.53
2.25
81,859
1.76
- 5. A drainage and access easement will be dedicated by separate document for the expanded
pond.
6. The existing outlet structure consists of a 12" ADS storm pipe at a headwall with a
restrictor plate. bolted to the headwall. It will be replaced with -a new headwall which will
have an seven and seven eigths inch (7 7/8") orifice on the upstream side and 415 lineal
feet of 15" ADS N-12 with a slope of 0.004 ft/ft. The 7 7/8" orifice will be created by
installing an orifice plate
Release
Elevation
Rate
Note
(ft.)
(cfs)
4939.75
0.00
4940.00
0.00
4940.50
1.13
4941.00
1.66
4941.50
2.07
Top of Type 2 outlet structure
4941.91
2.35
Req'd 100-year W.S.EI per stage storage
4941.94
2.37
Actual 100-year W.S.EI. per outlet hydraulics
4941.95
2.37
Overflow Weir Elevation
4942.00
2.98
Top of berm
A 20 foot wide emergency overflow weir has been provided at an elevation of 4941.95
feet. A detail of the overflow weir is shown on the Drainage and Erosion Control Plan.
7. The outlet pipe, a 15" ADS N-12 pipe, has a capacity of 4.42 cfs based on a HW/D ratio
of 1.0 and a Mannings n of 0.012. Riprap with a D. of 12" will be placed at the outfall of
the pipe. Refer to page 8 in Appendix I.
Page 7
Final Drainage and Erosion Control Report
Project No: 1409-03-96
IV. DRAINAGE FACILITY DESIGN:
B. Specific Details
8. The roadside ditch along North Lemay will be regraded in order to lower the bottom of
the detention pond on Lot 1 of the Second Replat of the North Lemay Subdivision. The
swale has the following geometry and flow capacity. Refer to page 9 in the drainage
calculations located in appendix I.
a. Slope = 0.0105 ft/ft
b. Bottom width = 1.0 feet
c. Depth = 2.0 feet
d. Side Slopes = 2 : 1 (H:V)
e. Capacity = 47.76 cfs
V. EROSION CONTROL:
A. General Concept
1. Erosion control measures are identified on the Master Drainage and Erosion Control
plan.
a. Maintenance of erosion control devices will remain the responsibility of Vanworks,
Inc. until the project has been completed.
B. Specific Details
1. Haybale dikes will be provided at the detention pond outlet structure.
2. A 20 foot long riprap apron will be placed at the downstream end of the outlet pipe from
the detention pond. The riprap shall be Y wide. The riprap shall have a Dso = 12".
e ter.,
Page 8
Final Drainage and Erosion Control Report
Project No: 1409-03-96
VI. EROSION CONTROL SECURITY DEPOSIT:
A. An erosion control security deposit is required in accordance with City of Fort Collins policy
(Chapter 7, Section C : SECURITY; page 7.23 of the City of Fort Collins Development
Manual). In no instance shall the amount of the security be less than $1000.00.
1. According to current City of Fort Collins policy, the erosion control security deposit is
figured based on the larger amount of 1.5 times the estimated cost of installing the
approved erosion control measures or 1.5 times the cost to re -vegetate the anticipated
area to be disturbed by construction activity.
a. The cost to install the proposed erosion control measures is approximately $ 590.00
Refer to the cost estimate attached in Appendix I. 1.5 times to install the erosion
control measures is $ 885.00.
b. Based on current data provided by the City of Fort Collins Storm Water Utility, and
based on an actual anticipated net affected area which will be disturbed by
construction activity (approximately 5.74 acres), we estimate that the cost to re -
vegetate the disturbed area will be $ 3,650.64 ($ 636.00 per acre x 5.74 acres). 1.5
times the cost to re -vegetate the disturbed area is•$ 5,475.96. The $ 636.00 per acre
for re -seeding sites of greater than was quoted to us by the City of Fort Collins
Storniwater Utility staff.
2. The erosion control security deposit amount required for this project will be $ 5,475.96.
See the Erosion Control Security Deposit Requirements document located in Appendix I.
3. The erosion control security deposit is reimbursable.
VII. VARIANCE FROM CITY STANDARDS
A. Variance from City of Fort Collins requirements
1. With this report, we are formally requesting a variance from the City of Fort Collins
Standard regarding the minimum slopes in detention ponds and freeboard requirements
for detention ponds. Approval of this report represents the City's acceptance of these
requests. This request is based on the following design constraints;
a. The pond that will be modified to detain the runoff from Vanworks Second
Subdivision is an existing pond and the existing slopes are less than 1.0%. The pond
design was approved in 1993, apparently with no freeboard requirements.
b. There is an existing high point at the south end of the site which is at an elevation of
4942.14 feet. The proposed top of berm was set so as not to exceed this elevation.
Exceeding this elevation with the top of berm would result in unrestricted flow
leaving the site in a southerly direction.
c. An agreement has been reached between the 2 owners regarding the detention
easement. This restricts the amount of land available for detention.
Page 9
Final Drainage and Erosion Control Report
Project No: 1409-03-96
VIE. VARIANCE FROM CITY STANDARDS
A. Variance from City of Fort Collins requirements (continued)
2 With this report, we are formally requesting a variance from the City of Fort Collins
Standard regarding detaining all of the runoff from the 1/2 ROW of Buckingham Street
which fronts on the street. Approval of this report represents the City's acceptance of
these requests. This request is based on the following design constraints;
a. A four foot sidewalk culvert will be constructed at the northeast corner of the site to
intercept some of the flows from Buckingham Street.
b. Due to street slopes the inlet does not intercept all of the Q100.
c. We have . reduced the allowable release rate from the pond by the amount that
bypasses the inlet during the 100-year event.
VIM CONCLUSIONS:
A. Compliance with Standards
1. All drainage analysis has been performed according to the requirements of the City of
Fort Collins Storm Drainage Criteria Manual.
2. Proposed drainage improvements generally conform with the recommendations of the
City of Fort Collins Master Drainage Plan.
3. Proposed erosion control measures generally conform with the recommendations of the
City of Fort Collins standards.
B. Drainage Concept
1. The proposed drainage design for the Vanworks Subdivision Second Filing is effective
for the control of storm runoff with absolutely no downstream effects.
2. The proposed drainage design for the Vanworks Subdivision Second Filing has
absolutely no effect on City of Fort Collins Master Drainage Plan recommendations.
3. This report should be considered for the future Phelps-Tointon Addition with no major
design requirements for Phelps-Tointon when a building permit for the addition is applied
for. This report considers the future Phelps-Tointon Addition.
Page 10
Final Drainage and Erosion Control Report
Project No: 1409-03-96
IX. REFERENCES:
1. City of Fort Collins "Storm Drainage Design Criteria and Construction Standards'; May,
1984
2. City of Fort Collins 'Erosion Control Reference Manual"; January, 1991
3. Storm Drainage Report for Lot 1, Second Repiat of the North Lemay Subdivision,
Second Filing; prepared by Stewart & Associates, Dated October 27, 1993; Approved
October 29, 1993
APPENDIX I
Drainage Calculations
Erosion Control Calculations
FLOW SUMMARY FOR VANWORKS SECOND SUBDIVISION PAGE 1
DESIGN CONTRIBUTING AREA C2 C10 C100 Tc Tc 12 I10 I100 Q2 Q10 Q100 DESIGN
POINT SUB 2,10 100
BASIN(S) ac. min. min iph iph iph cfe cfe cfe
rrrrr+rr+r+rrrrrrrrrr+rrrr:rrrrrr:e rrre rtrttt rrrttrt rtttrrrrttttratrtarr rr++r++rrr:rrrrrr+rrrrrrr+rr
DP A -EXIST 14.76 0.31 0.31 0.39 72.00 69.50 0.81 1.42 2.31 3.71 6.50 13.30
DP A -DEVELOPED 14.76 0.48 0.48 0.60 72.00 69.50 0.81 1.42 2.31 5.74 10.06 20.45
1 ROW 0.36 0.83 0.83 1.00 5.00 5.00 3.29 5.64 9.30 0.98 1.69 3.35
NOTE: RELRATE = RELEASE RATE FROM DETENTION POND IS THE HISTORIC 2-YEAR FLOW
THE ACTUAL RELEASE RATS FROM THE POND IS LESS THAN THE HISTORIC 2-YEAR FLOW FROM THE OVERALL .
AREA IN ORDER TO COMPENSATE FOR SOME OF THE BUCKINGHAM FLOWS WHICH DO NOT ENTER THE SITE
DUE TO THE TOPOGRAPHY OF THE ROAD AND THE SITS.
SUBBASIN A INCLUDES ROW
ROW IS THE 1/2 ROW IN FRONT OF THE VANWORKS SITE BEING DEVELOPED
SHEAR ENGINEERING CORPORATION
PAGE 2
SUBBASIN BREAKDOWN
PROJECT: VANWORKS SECOND SUBDIVISION
PROJECT NO 1409-03-96 DATE: 06/12/96
PROJECT LOCATION :BAST LINCOLN AVE BY HBO
FORT COLLINS FILE: VANRUN
SITES PLATTED AREA 1/2 ROW AREA ON BUCKINGHAM
VANWORKS 9.54 ACRES 0.28 ACRES
PHELPS-TOINTON 6.01 ACRES 0.30 ACRES
TOTAL 15.55 ACRES 0.58 ACRES
IM-
BASIN PERVIOUS PERVIOUS
ROOF/ GRAVEL LAWN C2 C100
SF ACRES DRIVES
0.95 0.50 0.20
x rt t++r++++++f:rtterre+r+++r+f++++tx:rrrrr+f++tr:rrr++t+trf+t+t++r+trxxr
DEVELOPED CONDITIONS
VANWORKS SITE - NORTHERN PORTION TO BE DEVELOPED
STREET-1 12138 0.28 0.24 0.00 0.04 0.85 1.00
I
ONSITE 309711 7.11 0.46 4.42 2.23 0.44 0.54
OFPSITB 46052 1.06 0.00 0.00 1.06 0.20 0.25
SUBTOTAL 321849 8.45 0.70 4.42 3.33 0.42 0.52
PHELPS-TOINTON SITE
STREET-2 13068 0.30 0.24 0.00 0.06 0.80 1.00
ONSITE 261796 6.01 2.74 0.00 3.27 0.54 0.68
SUBTOTAL 274864 6.31 2.98 0.00 3.33 0.55 0.69
TOTAL 596713 14.76 3.68 4.42 6.66 0.477 0.596
1/2ROW VW 15568 0.36 0.30 0.00 0.06 0.831 1.000
♦tr+rrr+rrrf r++++r+fftftrtrtrrrrrf++fffttrrrrrff+♦++tttrrrrrfrrttrrrf+f ♦ttttrr+e•
HISTORIC C FACTOR TO POND ON PHELPS-TOINTON SITE
PHELPS-TOINTON SITE- PRBDBVBLOPBD
STREET-2 13068 0.30 0.24 0.00 0.06 0.80 1.00
ONSITE 261796 6.01 0.00 0.00 6.01 0.20 0.25
SUBTOTAL 274864 6.31 0.24 0.00 6.07 0.23 0.29
VANWORKS SITE- EXISTING CONDITIONS
ONSITE 309711 7.11 0.00 4.27 2.84 0.38 0.48
OFFSITE 46052 1.06 0.00 0.00 1.06 0.20 0.25
STREET -le 12138 0.28 0.13 0.00 0.15 0.55 0.68
SUBTOTAL 367901 8.45 0.13 4.27 4.05 0.36 0.45
NO STREET 617559 14.18 0.00 4.27 9.91 0.29 0.36
TOTAL 642765 14.76 0.37 4.27 10.12 0.31 0.38
♦rxrttttxtrtrrxtrrr++f rrtt++tttrxrrfr++rttrtttrxtr++ttrttttttxtf tr+trtxt
NOTES: ONSITE 2 VANWORKS IS ASSUMED TO BE 604 GRAVEL AND 404 GRASS
OFFSITE IS ALL GRASS
THE EXISTING BUILDING ON THE VANWORKS SITE IS NOT CONSIDERED
STREET -le IS 15.75 FEET ASPHALT AND 18.25 FEET GRASS(46i/54i)
CONCLUDE:USE HISTORIC C FACTOR TO DETERMINE RELEASE RATE FROM POND. SEE PAGE 3A
USE DEVELOPED C FACTOR TO DETERMINE REQUIRED POND VOLUME. SEE PAGE 6
f '
SHEAR ENGINEERING CORPORATION
'
HISTORIC FLOW TO
PAGE 3
DETENTION POND SITE ® PHBLPS TOINTON
SITE AND BUCKINGHAM STREET
PROTECT: VANWORKS SECOND SUBDIVISION
DATE 06/11/96
LOCATION:900 EAST LINCOLN AVENUE
PROJ. NO.1409-03-96
FORT COLLINS
BY .HBO
FILE: VANRUN
AREA (A)= 14.760 ACRES
RUNOFF COEF. (C) ,
2 YEAR 10 YEAR 100 YEAR
C 0.31 0.31 0.39
SEE SPREAD SHEET ATTACHED ON PAGE 2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti)
LENGTH = 500 FEET SLOPE 0.43 1
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 49.72 49.72 46.96
TRAVEL TIME (TO=L/(603V) y. FLOW TYPE
L (ft) = 730 S (6) = 0.6 LAWN
V (fps) = 0.54
Tt(min)= 22.53
L (ft) _? S (;) _? ?
V (fps) _?
Tt(min)= 0.00
L (ft) _? S (•) _? ?
V (fps) =7
Tt(min)= 0.00
• (ft) _? S 00 _? ?
V (fps) _?
Tt(min)= 0.00
L (ft) _? S (6) _? ?
V (fps) _?
Tt(min)= 0.00
L (ft) _? S (i) _? ?
V (fps) _?
Tt(min)= 0.00
L (ft) _? S (4) _? ?
V (fps) _?
Tt(min)= 0.00
NOTE: ALL VELOCITIES TAKEN FROM FIGURE 3-2
TOTAL TRAVEL TIME
(min) 22.53
Tc =Ti+TOTAL TRAVEL TIME
"
2 YEAR 10 YEAR 100 YEAR
Tc (min)= 72.25 72.25 69.49
USE Tc = 72 72 69.5
INTENSITY (I) (iph)
2 YEAR 10 YEAR 100 YEAR
I = 0.81 1.42 2.31
NOTE: INTENSITIES TAKEN FROM FIGURE 3-1
RUNOFF (Q= CIA) (cfs)
2 YEAR 10 YEAR 100 YEAR
Q = 3.71 6.50 13.30
NOTES: INCLUDES 7.11 ACRES FROM VANWORKS SITE
INCLUDES 1.06 ACRES OFFSITE AREA WEST OF
VANWORKS
INCLUDES 0.58 ACRES 1/2 ROW FRONTING ON
BOTH SITES
INCLUDES 6.01 ACRES FROM PHELPS TOINTON
SITS
CONCLUDE:ONLY SOME OF THE STREET FLOWS ARE DIVERTED INTO
THE SITE. THEREFORE REDUCE
RELEASE RATS FROM POND BY THE AMOUNT OF Q100
IN STREET THAT BYPASSES.
SEE PAGE 3A
SHEAR ENGINEERING CORPORATION
DEVELOPED PLOW FROM BUCKINGHAM STREET PAGE 3A
TO NORTHEAST CORNER OF SITE.
PROJECT: VANWORKS SECOND SUBDIVISION
DATE
06/12/96
LOCATION:900 EAST LINCOLN AVENUE
PROJ. NO.1409-03-96
PORT COLLINS
BY
HBO
PILE: VANRUN
AREA (A)= 0.36 ACRES
RUNOFF COED. (C)
2 YEAR 10 YEAR 100 YEAR.
C = 0.83 0.83 1.00
SEE SPREAD SHEET ATTACHED ON PAGE 2
TIME OF CONCENTRATION (Tc)
OVERLAND TRAVEL TIME (Ti) NOT APPLICABLE
LENGTH = FEET SLOPE =NA It
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 0.00 0.00 0.00
TRAVEL TIME (Tt) =L/(60*V) PLOW TYPE
L (ft) = 458 S (4) = 0.5 GUTTER
V (fps)
= 1.5 Tt(min)-
5.09
L (£t) _? S (t) _? ?
V (fps)
_? Tt(min)=
0.00
L (ft) _? S (!) _? ?
V (fps)
_7 Tt(min)=
0.00
L (ft) _? S (i).=? ?
V (fps)
_? Tt(min)=
0.00
L (ft) _? S (t) _? ?
V (fps)
_? Tt(min)=
0.00
L (ft) _? S (i) _? ?
V (fps)
_? Tt(min)=
0.00
L (ft) _? S (i) _? ?
V (fps)
_? Tt(min)=
0.00
NOTE: ALL VELOCITIES TAKEN FROM FIGURE 3-2
TOTAL TRAVEL TIME (min)
5.09
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR 10 YEAR 100 YEAR
Tc (min)= 5.09 5.09 5.09
USE Tc = 5 5 5
INTENSITY (I) (iph)
2 YEAR 10 YEAR 100 YEAR
I = 3.29 5.64 9.30
NOTE: INTENSITIES TAKEN FROM FIGURE 3-1
RUNOFF (Q= CIA) (cfs)
2 YEAR 10 YEAR 100 YEAR
Q = 0.98 1.69 3.35
CONCLUDE:INSTALL 4 FOOT SIDEWALK CULVERT
T = 7.2 ft Sx - 0.0269 ft/ft
FROM FIGURE 5-5 QI/Q = 0.75
INTERCEPTED PLOW = 2.51 CPS REDUCE BY
80.00lt
ACTUAL PLOW INTERCEPTED = 2.01 CPS
BYPASSING FLOW = 1.34 CPS
REDUCE RELEASE RATE FROM POND BY 1.34 CPS
SHEAR ENGINEERING CORPORATION
FOR REFERENCE ONLY
DEVELOPED FLOW TO
PAGE
4
DETENTION POND SITE ® PHELPS TOINTON
FROM PHSLPS-TOINTON AND VANWORKS SITES
PROJECT: VANWORKS SECOND SUBDIVISION
DATE
06/11/96
LOCATION:900 EAST LINCOLN AVENUE
PROJ. NO.1409-03-96
FORT COLLINS
BY
MEO
FILE: VANRUN
AREA (A)= 14.760 ACRES
-
RUNOFF COBF. (C)
2 YEAR 10 YEAR 100 YEAR
C 0.48 0.48 0.60
SEE SPREAD SHEET ATTACHED ON PAGE 2
TIME OF CONCENTRATION (Tc) SAME AS EXISTING CONDITIONS
OVERLAND TRAVEL TIME (Ti)
LENGTH = 500 FEET SLOPE 0.43 i
2 YEAR 10 YEAR 100 YEAR
C = 0.20 0.20 0.25
Ti (min)= 49.72 49.72 46.96
TRAVEL TIME (Tt)=L/(60*V) PLOW TYPE
L (ft) = 730 S (14) = 0.6 LAWN
V
(fps)
= 0.54
Tt(min)=
22.53
L (ft) =7 S (k) _? ?
V
(fps)
_?
Tt(min)=
0.00
L (ft) =7 S (k) _? ?
V
(fps)
_?
Tt(min)=
0.00
L (ft) _? S M _? ?
V
(fps)
_?
Tt(min)=
0.00
L (ft) _? S (6) _? ?
V
(fps)
_?
Tt(min)=
0.00
L (ft) _? S M _? ?
V
(fps)
_?
Tt(min)=
0.00
L (ft) _? S (a) _? ?
V
(fps)
_?
Tt(min)=
0.00
NOTE: ALL VELOCITIES TAKEN FROM FIGURE 3-2
TOTAL TRAVEL TIME
(min) =
22.53
Tc =Ti+TOTAL TRAVEL TIME
2 YEAR 10 YEAR 100 YEAR
Tc (min)= 72.25 72.25 69.49
USE Tc 72 72 69.5
INTENSITY (I) (iph)
2 YEAR 10 YEAR 100 YEAR
I = 0.81 1.42 2.31
NOTE: INTENSITIES TAKEN FROM FIGURE 3-1
RUNOFF (Q= CIA) (cfe)
2 YEAR 10 YEAR 100 YEAR
Q = 5.74 10.06 20.46
NOTES: INCLUDES 7.11 ACRES FROM VANWORKS SITE
INCLUDES 1.06 ACRES OFFSITR AREA WEST OF VANWORKS
INCLUDES 0.58 ACRES 1/2 ROW FRONTING ON BOTH SITES
INCLUDES 6.01 ACRES FROM PHSLPS TOINTON SITE
CONCLUDR:DETAIN FLOWS IN PHSLPS TOINTON POND AND RELEASE AT HISTORIC 2-YEAR RATE
SEE PAGE 3A
SHEAR ENGINEERING CORPORATION
PAGE 5
AVERAGE END AREA METHOD
FOR DETENTION BASIN
VOLUMES
EXISTING POND- ASBUILT
PROJECT :VANWORKS DATE: 08/27/97
PRAT. NO:1409-03-96 BY MBO
LOCATION:900 B LINCOLN AVE FILE: POND2
NOTES :EXISTING POND ON PHELPS - TOINTON INC. SITE
DESIGNED BY STEWARTS & ASSOCIATES
INVERT 4939.95 FEET FIRST EVEN CONTOUR 4940 FEET
INCREMENT 1 FOOT TOP ELEV 4941.6 FEET
STAGE BLEV. AREA VOLUME CUM. CUM. CUM.
(A2) (V1) VOLUME VOLUME VOLUME
ft ft aq ft cf cf cy ac-ft
+e+++•+• •erne ee+ re+:e++• ++e++++r +e+e++:+ +r•+++re rerererr ._ ..
0.00 4939.95 0 0 0 0 0.00
0.05 4940 30 0 0 0 0.00
1.05 4941 18813 9422 9422 349 0.22 .y
1.65 4941.6 72076 27267 36689 1359 0.84-
reeeeee:e:r++r++r+++++rt+tre++r+a +rre+rt+t ttttee a+er+++rrr+++r+ .
DETENTION REQUIREMENT PER STEWARTS REPORT = 32298 CP
OUTLET PIPE FROM POND IS A 12 "ADS N-12 PIPE
INVERT Q POND 4939.95 FEET BASED ON TOPO SURVEY BY INTBRMILL
PIPS LENGTH = 20 PERT _
INVERT W OUTPALL = 4939.91 PERT BASED ON TOPO SURVEY BY INTERMILL
SLOPE 0.002 PT/PT
0.20%
PIPE CAPACITY USING MANNINGS & ASSUMING N = 0.012 & HW/D -1.0
AREA = 0.79 SP SLOPE = 0.002 PT/PT
CIRCUMFERENCE = 3.14 FT n = 0.012
HYD. RADIUS (R) 0.25 FT
CAPACITY = 1.73 CPS
RELEASE RATE FROM POND PER STEWARTS REPORT = 2.04 CPS
SHEAR ENGINEERING
CORPORATION `
PAGE 6
DETENTION
VOLUME REQUIRED FOR
PROPOSED
POND
PROJECT: VANWORKS SECOND
SUBDIVISION
DATE:
08/27/97
PRO7.NO. 1409-03-96
FILE: POND2
BY
MEO
CUMULATIVE RUNOFF
METHOD
FOR
SIZING DETENTION PONDS
DESIGN STORM:
100
YEAR
RUNOFF COEFFICIENT
0.60
RELEASE RATE:
2.37
CPS
AREA:
14.76
ACRES
RELEASE RATE
COMPENSATE FOR BYPASSING FLOWS
INITIAL TIME:
5
MINUTES
TIME INCREMENT:
5
MINUTES
INFLOW
INFLOW
RELEASE
STORAGE
STORAGE
TIME TIME INTENSITY RATE
VOLUME
VOLUME
VOLUME
VOLUME
min sac
iph
cfe
cf
cf
cf
ac-ft
+11ff11f tf 1f}r 111fff}f}!}!l+tlf}!tf!}lftl1t
1f 1ff 1t 11 t1r+)11rf+fYYr
if lftr '
5
300
9.30
82.36
24708.2
711.0
23997.2
0.55
10
600
7.14
63.23
37939.1
1422.0
36517.1
0.84
15
900
6.06
53.67
48300.6
2133.0..
46167.6
1.06:
20
1200
5.21
46.14
55367.7"
2844.0
52523.7
1.21
25
1500
-4.63
41.00
61504.9
3555.0
57949.9
1.33
30
1800
4.20
37.20
66951.4
4266.0
62685.4
1.44
35
2100
3.91
33.74
70856.9
4977.0
65879.9
1.51,
40
2400
3.60
31.88
76515.8
5688.0
70827.8
1.63
45
2700
3.28
29.05
78428.7
6399.0
72029.7
1.65
50
3000
3.02
26.75
80235.4
7110.0
73125.4
1.68
55
3300
2.80
24.80
81829.4
7821.0
74008.4
1.70
60
3600
2.60
23.03
82892.2
8532.0
74360.2
1.71
65
3900
2.43
21.52
83928.3
9243.0
74685.3
1.71
70
4200
2.30
20.37
85549.0
9954.0
75595.0
1.74
75
4500
2.17
19.22
86478.8
10665.0
75813.8
1.74
80
4800
2.07
18.33
87993.2
11376.0
76617.2
1.76
85
5100
1.96
17.36
88524.6
12087.0
76437.6
1.75
90
5400
1.87
16.56
89427.9
12798.0
76629.9
1.76 •*
95
5700
1.77
15.68
89348.2
13509.0
75839.2
1.74
100
6000
1.70
15.06
90331.2
14220.0
76111.2
1.75
105
6300
1.63
14.44
90942.3
14931.0
76011.3
1.74
110
6600
1.57
13.90
91765.9
15642.0
76123.9
1.75
115
6900
1.50
13.28
91659.6
16353.0
75306.6
1.73
120
7200
1.44
12.75
91819.0
17064.0
74755.0
1.72
ffrrrlrrrrrr:frr rr lure rrr!•}}rr}!t!♦1tl11tftt+rlf!}}er:
rrrllrrrlrr:f tf!
DETENTION VOLUME REQUIRED
= 76630
cf
DETENTION VOLUME REQUIRED
- 1.76
ac-ft
EXISTING POND HAS
36689
CF OF AVAILABLE STORAGE VOLUME
0.84
AC -FT
CONCLUDE:PROVIDE
39941
CP OF ADDITIONAL STORAGE
0.92
AC -FT
SHEAR ENGINEERING CORPORATION
PAGE 7
AVERAGE END AREA METHOD
FOR DETENTION BASIN
VOLUMES
PROPOSED POND
PROJECT :VANWORKS DATE: 08/27/97
PROS. NO:1409-03-96 BY MEO
LOCATION:900 E LINCOLN AVE FILE: POND2
NOTES :REDESIGNED GRADING OF POND ON PHELPS - TOINTON INC. SITE
INVERT 4939.75 FEET FIRST EVEN CONTOUR 4940 FEET
INCREMENT 1 FOOT TOP ELEV 4942 FEET
r+rrrtrt rtttttrr rrrr r+++ rrr:rrtr ttr++r++ r+rr+trr tr+rrrr+
STAGE ELEV. AREA VOLUME CUM. CUM. CUM.
(A2) (V1) VOLUME VOLUME VOLUME
ft ft sq ft cf cf cy ac-ft
t rrrr+++ rr:rrr r: Terre rrr •����++r rrrrrrrr err tt t++ rr rrrr rr
0.00 4939.75 0 0 0 0 0.00
0.25 4940 1800 149 149 6 0.00
1.25 4941 44441 23121 23269 862 0.53
2.25 4942 72739 58590 81859 3032 1.88
rt ttt t++rr+rre:rrr+r+r:+rrrrtt t:tt++t+++r+++r+rrrtrttr t+++++r++
DETENTION REQUIREMENT = 76630 CP .1.76 AC -FT
REFER TO PAGE 3 IN DRAINAGE CALCULATIONS
EXCESS STORAGE VOLUME = 5229 CP = 0.12 AC -FT
POND VOLUME 1 FOOT BELOW TOP OF BERM = 81859 CP c 76630 CP
REQUIRED W.S. BLEV. = 4941.91 FEET
SET EMERGENCY OVERFLOW ELEVATION N 4941.95 FEET
APPROXIMATE VOLUME @ EMERGENCY OVERFLOW 78929 CF
1.81 AC -FT
CONCLUDE:POND HAS ADEQUATE VOLUME
REQUEST VARIANCE FROM 1 FOOT FREEBOARD REQUIREMENT
SHEAR ENGINEERING CORPORATION
PAGE 8
PROPOSED'OUTLET STRUCTURE
PROJECT: VANWORKS
DATE: 08/27/97
PROJECT NO 12409-03-96
BY MEO
PROJECT LOCATION :BUCKINGHAM STREET
FILE: POND2
PORT COLLINS
INPUT FOR OUTLET STRUCTURE
HEADWALL WITH ORIFICE PLATE
LOWER ORIFICE DIAM. (ft).=
0.65
TOP OF BERM (ft)
- 4942.00
DETERMINE ORIFICE
LOWER ORIFICE INV. (ft) =
4939.75
INIT. DELTA (ft)
= 0.25
SIZE"
LOWER ORIFICE CORP. (Cl) -
0.65
DELTA HEAD (ft)
- 0.50
FOR 100-YEAR STORM
100 YR RELEASE RATE (cfe)=
2.37
OVER PLOW
yes
Q= CA(29H)"0.5
Q100 TO POND (cfe) =
20.45
WEIR TYPE
BROADCRESTED
A = Q/(C(29H)A0.5
OUTLET PIPE DIAM. (£t) =
1.25
WHIR LENGTH (ft)
= 20.00
H (ft) - 2.16
PIPE SLOPE (t)
0.40
WHIR INVERT (ft)
= 4941.95
C = 0.65
MANNINGS n, =
0.012
WEIR COEF. (Cwo)
- 2.60
Q (cfs)= 2.37
100.YR WSEL REQUIRED (ft)=
4941.91
A (of) = 0.31
tr♦+rr+r r+++++++ rtrrtrtr
*OUTPUT*
trrrrrrr trrr rr rt
tr+trttr r:rrrxrt
R (ft) = 0.314
PIPB AREA (SP) = 1.23
WETTED PERIMETER
= 3.93 FEET
D (ft) = 0.627
HYD. RAD (FT) = 0.313
PEST
RA2/3 = 0.4603
OUTLET PIPE CAPACITY =
4.42
CPS
LOWER ORIFICE'ARRA".(A) _
0.3310.SQUARE.FBBT
rt+++++ +r+r++t +e+rrtt
*OUTPUT*
tt ttrt• ttttret
erettrt rrrrr rr
OVERFLOW SPILLWAY
xt+t+x+ t+txt+t
ttrxrrt
HEAD
SUB
HEAD
BLEV. OVER LOWER
TOTAL
OVER WEIR
TOTAL
LOWER ORIFICE
FLOW
WHIR FLOW
PLOW
ORIFICE PLOW
ft ft cfe
cfe
ft cfe
cfe
4939.75 0.00 0.00
0.00
0.00 0.00
0.00
4940.00 0.00 0.00
0.00
0.00 0.00
0.00
4940.50 0.43 1.13
1.13
0.00 0.00
1.13
4941.00 0.93 1.66
1.66
0.00 0.00
1.66
4941.50 1.43 2.07
2.07
0.00 0.00
2.07
4942.00 1.93 2.40
2.40
0.05 0.58
2.98
4941.942 1.87 2.37
2.37
0.00 0.00
2.37
4941.91 1.84 2.35
2.35
0.00 0.00
2.35
4941.95 1.87 2.37
2.37
0.00 0.00
2.37
r rttttt+ t:rttttt ettrttrr
txxxxxxx
rxttttrt rtrrtrtr
trrrrttr
ORIFICE EQUATION: CA(29H)"1/2 WEIR FLOW BQTN. : CWL.HA3/2
NOTE: HEAD OVER ORIFICE = HEAD OVER CENTER OF ORIFICE
CONCLUDE:TARGHT ELEVATION IS EQUALED 4941.94 > 4941.91
RELEASE RATE - 2.37 CPS ® ELEV. - 4941.942 PEET
ADEQUATE STORAGE IS PROVIDED SEE PAGE 7
FRBEBOARD PROVIDED = 0.06 FEET - REQUEST VARIANCE
SHEAR ENGINEERING CORPORATION
PAGE 9
CHANNEL CAPACITY -OUTLET FROM POND
PROJECT NAME: VANWORKS DATE: 07/23/96
PROTECT NO. 1409-03-96 BY : MEO
PILE: VANCHAN
SWALE DESCRIPTION:WEST SIDS OF LEMAY AVENUE
CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL
CHANNEL CONFIGURATION: TRAPEZOIDAL DESIGN PLOW (cfe)= 31.42
CHANNEL LINING: GRASS Capacity of 30" ADS W 0.5k
Da Db Dc Sc n W I
(ft) (ft) (ft) (k) (ft) (ft)
---- ---- ---- ---- ----- ---- ----
4.00 4.00 2.00 1.05 0.032 1.00 0.25
0.50 = LEFT BANK SLOPE 2 1 (H:V)
0.50 = RIGHT BANK SLOPE 2 1 (H:V)
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2. Q V
(e.f.) (ft) (e.f.) (ft) (A/P) (cfe) (ft/sec)
----------------------------------- -------------- -------
2.00 9.00 10.00 9.94 1.00 0.10 47.76 4.78
1.75 6.00 7.88. 8.83 0.93 0.10 34.73 4.41
1.50 7.00 6.00 7.71 0.85 0.10 24.16 4.03
1.25 6.00 4.38 6.59 0.76 0.10 15.84 3.62
1.60 7.40 6.72 8.16 0.88 0.10 28.10 4.18
ee ttt+trtr utter+tetttttrrrrtereet tttttrr eteeeerrttt+t+errrrr+++rttrtree
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(B.f.) (ft) (e.f.) (ft) (A/P) (cfe) (ft/sec)
NOTE: DESIGN PLOW IS BASED ON DESIGN CAPACITY OF 30" CULVERT AT K-VENTURE
PROPERTY ON NORTH LBMAY
PLOW DEPTH FOR THE DESIGN PLOW IS APPROXIMATELY 1.60 FEET
CONCLUDE:CNANNEL IS ADEQUATE
SHEAR BNGINSBRING CORPORATION '
PAGE 11
CHANNEL CAPACITY -CHANNEL ALONG EAST PROPERTY LINE
PROJECT NAME: VANWORKS DATE: 07/24/96
PROTECT NO. 1409-03-96 BY : MEO -
FILE: VANCHAN
SWALE DESCRIPTION:WEST SIDE OF LBMAY AVENUE
CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL
CHANNEL CONFIGURATION: TRIANGULAR DESIGN FLOW (cfs)= 2.01
CHANNEL LINING: GRASS FLOW FROM BUCKINGHAM SIDEWALK CULVERT
Da Db Dc Sc. n W I
(ft) (ft) (ft) (4) (ft) (ft)
---- ---- ---- ---- ----- ---- ----
8.00 8.00 0.50 0.50 0.032 0.00 0.10
0.06 = LEFT BANK SLOPE 16 1 (H:V)
0.06 = RIGHT BANK SLOPE 16 1 (H:V)
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfe) (ft/sec).
--------------------------------------------------------
0.50 16.00 4.00 16.03 0.40 0.07 5.21 1.30
0.40 12.80 2.56 12.82 0.34 0.07 2.87 1.12
0.30 9.60 1.44 9.62 0.28 0.07 1.33 0.93
0.20 6.40 0.64 6.41 0.22 0.07 0.45 0.71
0.35 11.20 1.96 11.22 0.31 0.07 2.01 1.03
++rrr+rer+r•rrrr+++++++++r++rrr++++e+r+r++r++++rr+rrrr+rrr+r+rr+rrrer+++
DEPTH WIDTH' AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfe) (ft/sec)
NOTE: DESIGN FLOW 'IS BASED ON FLOW INTERCEPTED BY SIDEWALK CULVERT
FLAW DEPTH FOR THE DESIGN FLOW IS APPROXIMATELY 0.35 FEET
CONCLUDE:CHANNBL IS ADEQUATE
SHEAR ENGINEERING CORPORATION
PAGE 10
CHANNEL CAPACITY -OUTLET FROM POND
PROJECT NAME: VANWORKS DATE: 07/24/96
PROJECT NO. 1409-03-96 BY : MEO
FILE: VANCHAN
SWALE DESCRIPTION:IN EASEMENT ON LOT 2 SECOND REPLAT OF NORTH LSMAY SUBDIVISION
CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL
CHANNEL CONFIGURATION: TRAPEZOIDAL DESIGN FLOW (cfe)= 20.45
CHANNEL LINING: GRASS
Da Db Dc Sc n W I
(ft) (ft) (ft) (4) (ft) (ft)
5.00 5.00 1.25 0.50 0.032 2.00 0.25
0.25 - LEFT BANK SLOPE 4 : 1 (H:V)
0.25 - RIGHT BANK SLOPS 4 : 1 (H:V)
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfe) (ft/sec)
------------------------------------------------- ------- .
1.25 12.00 8.75 12.31 0.80 0.07 22.89 2.62
1.00 10.00 6.00 10.25 0.70 0.07 13.79 2.30
0.75 8.00 3.75 8.18 0.59 0.07 7.32 2.95
0.50 6.00 2.00 6.12 0.47 0.07 3.11 1.56
1.19 11.52 8.04 11.81 0.77 0.07 20.45 2.54
r rrr+ttrrrrrrrrrtrtt rrr+r+rrrrr:rtr:errrrrtrr+rrrrrer ttrrtttttttttr ttrrr
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(e.f.) (ft) (s.f.) (ft) (A/P) (cfe) (ft/sec)
FLOW DEPTH FOR THE DESIGN FLOW IS APPROXIMATELY 2.19 PERT
FOR Q100 = 20.45 CPS FLOW DEPTH = 1.19 FEET
CONCLUDE:CHANNEL IS ADEQUATE
July 24, 1997
Project No. 1409-03-96
Basil Hamdan
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: Vanworks Subdivision Second Filing; Fort Collins, Colorado
Dear Basil,
Attached is the erosion control security deposit estimate for Vanworks Subdivision Second
Filing.
ESTIMATE 1:
1 - Hay bale barrier at outlet structure ® 125.00 each $ 125.00
3 - Haybale barriers in swale ® 125.00 each $ 375.00
3 - cubic yards riprap apron @ 30.00 per cubic yard $ 90.00
TOTAL ESTIMATED COST: $ 590.00 .
x 1.50
$ 885.00
ESTIMATE 2:
re -vegetate the disturbed area of 5.74 acres at $ 531.00 per acre $ 3,047.94
TOTAL ESTIMATED COST: $ 3,047.94
x 1.50
$ 4,571.91
The total required erosion control security deposit will be $ 4,571.91
If you have any questions, please call at 226-5334.
Sincerely,
J U5 \V' V ��
Mark Oberschmidt
Shear Engineering Corporation
MO / meo
cc: Keith Hess
Dave Stringer, City of Fort Collins
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282.0311
July 24, 1997
Project No. 1409-03-96
SHEAR
ENGINEERING
CORPORATION
Re: EROSION CONTROL SECURITY DEPOSIT REQUIREMENTS:
Vanworks Subdivision Second Filing; Fort Collins, Colorado
A. An erosion control security deposit is required in accordance with City of Fort Collins
policy (Chapter 7, Section C: SECURITY; page 7.23 of the City of Fort Collins
Development Manual). In no instance shall the amount of the security be less than
$ 1000.00.
1. According to current City of Fort Collins policy, the erosion control security deposit
is figured based on the larger amount of 1.5 times the estimated cost of installing
the approved erosion control measures or 1.5 times the cost to re -vegetate the
anticipated area to be disturbed by construction activity.
a. The cost to install the proposed erosion control measures is approximately
$590.00. Refer to the cost estimate attached in Appendix I. 1.5 times to install
the erosion control measures is $ 885.00.
b. Based on current data provided by the City of Fort Collins Stormwater Utility,
and based on an actual anticipated net affected area which will be disturbed by
construction activity (approximately 5.74 acres), we estimate that the cost to re -
vegetate the disturbed area will be $3,047.94 ($ 531.00 per acre x 5.74 acres).
1.5 times the cost to re -vegetate the disturbed area is $4,571.91 The $ 531.00
per acre for re -seeding sites of greater than was quoted to us by the City of Fort
Collins Stormwater Utility staff.
CONCLUSION:
The erosion control security deposit amount required for Vanworks Second Subdivision
will be S 4,571.91
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226.5334 FAX (970) 282-0311
I
RAINFALL PERFORMANCE STANDARD EVALUATION
PROJECT: VANWORKS SECOND SUBDIVISION STANDARD FORM A
COMPLETED BY: MEO DATE: 09/11/96
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DEVELOPED ERODIBILITY Aeb Lob Sob Lb Sb PS
SUBBASIN ZONE (ac) (ft) (6) (feet) (4) (a)
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A MODERATE 14.76 1230 0.53 18154.80 7.82
0.00 0.00
0.00 0.00
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0.00 0.00
0.00 0.00
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0.00 0.00
0.00 0.00
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SLOPS
LENGTH 0.50 0.53 1.00
1200 72.7 73.042 78.4
1230
1300 72.7 73.042 78.4
PERFORMANCE STANDARD = 73.04% I
EFFECTIVENESS CALCULATIONS
PROJECT: \(q\iJVJpRyS Svf3DIVIS10N STANDARD FORM B
d o
COMPLETED BY: MCu' SlidRR E,NGIN6 Cp,,\1(r DATE: cjkkb
Erosion Control C-Factor P-Factor
Method Value Value Comment
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CALCULATIONS
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MARCH 1991 8-15 DESIGN CRITERIA
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Table 8B C-Factors and P-Factors for Evaluating EFF Values.
Treatment C-Factor
P-Factor
BARE SOIL
Packed and smooth................................................................
1.00
1.00
Freshly disked........................................................................
1.00
0.90
Rough irregular surface...........................................................
1.00
0.90
SEDIMENT BASIN/TRAP.................................................................
1.00
0.50"'
STRAW BALE BARRIER, GRAVEL FILTER, SAND BAG ........................
1.00
0.80
SILT FENCE BARRIER.....................................................................
1.00
ASPHALT/CONCRETE PAVEMENT ...................................................
0.01
1.00
ESTABLISHED DRY LAND (NATIVE) GRASS .......................... See Fig.
8-A
1.00
SODGRASS.................................................................................
0.01
1.00
TEMPORARY VEGETATION/COVER CROPS .................................... 0.4512)
1.00
HYDRAULIC MULCH @ 2 TONS/ACRE........................................... 0.10"'
1.00
SOIL SEALANT....................................................................0.01-0.60141
1.00
EROSION CONTROL MATS/BLANKETS............................................
0.10
1.00
GRAVEL MULCH
Mulch shall consist of gravel having a diameter of approximately .
1 /4" to 1 1 /2" and applied at a rate of at least 135 tons/acre..............
0.05
1.00
HAY OR STRAW DRY MULCH
After planting grass seed, apply mulch at a rate of 2 tons/acre (minimum) and
adequately anchor,
tack or crimp material into the soil.
Slope (%)
1 to 05.............................................................................0.06
1.00
6 to 10.............................................................................
0.06
1.00
11 to 15.............................................................................
0.07
1.00
16 to 20.............................................................................
0.11
1.00
21 to 25.............................................................................
0.14
1.00
25 to 33.............................................................................0.17
1.00
> 33..........................................................................
0.20
1.00
NOTE: Use of other C-Factor or P-Factor values reported in this table must be substantiated by documentation.
(1) Must be constructed as the first step in overlot grading.
(2) Assumes planting by dates identified in Table 11-4, thus dry or hydraulic mulches are not required.
(3) Hydraulic mulches shall be used only between March 15 and May 15 unless irrigated.
(4) Value used must be substantiated by documentation.
MARCH 1991 8.6 DESIGN CRITERIA
APPENDIX H
Charts & Figures
No Text
R-M-P Medium Density Planned Residential District — designation for medium density
areas planned as a unit (PUD) to provide a variation in use and building placements
with a minimum lot area, of 6,000 square feet.
R-L-M Low Density Multiple Family District — areas containing low density multiple family
units or any other use in the R-L District with a minimum lot area of 6,000 square feet
for one -family or two-family dwellings and•9,000 square feet for multiple -family
dwellings.
M-L Low Density Mobile Home District — designation for areas for mobile home parks
containing independent mobile homes not exceeding 6 units per acre.
M-M Medium Density Mobile Home District — designation for areas of mobile home
parks containing independent mobile homes not exceeding 12 units per acre.
B-G General Business District — district designation for downtown business areas,
including a variety of permitted uses, with minimum lot areas equal to 1 /2 of the total
floor area of the building.
B-P Planned Business District — designates areas planned as unit developments to
provide business services while protecting the surrounding residential areas with
minumum lot areas the same as R-M.
H-B Highway Business District — designates an area of automobile -orientated busi-
nesses with a minimum lot area equal to 1 /2 of the total floor area of the building.
B-L Limited Business District — designates areas for neighborhood convenience
centers, including a variety of community uses with minimum lot areas equal to two
times the total floor area of the building.
C Commercial District —designates areas of commercial, service and storage areas.
I-L Limited Industrial District — designates areas of light industrial uses with a minimum
area of lot equal to two times the total floor area of the building not to be less than
20,000 square feet.
I-P Industrial Park District —designates light industrial park areas containing controlled
industrial uses with minimum lot areas equal to two times the total floor area of the
building not to be less than 20,000 square feet.
I-G General Industrial District — designates areas of major industrial development.
T Transition District — designates areas which are in a transitional stage with regard
to ultimate development.
For current and more explicit definitions of land uses and zoning classifications, refer to the
Code of the City of Fort Collins, Chapters 99 and 118.
Table 3-3
RATIONAL METHOD RUNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS
Character of Surface Runoff Coefficient
Streets, Parking Lots, Drives:
Asphalt...................................................................................................................................... 0.95
Concrete........................................................ 0.95
Gravel................................................................................................. 0.50
Roofs.......................................................................................................... 0.95
Lawns, Sandy Soil:
0.1
Flat<2%.............................................................................................
7%
0.5
Average2 to ..................................................................................
0.20
Steep>7%..........................................................................................
Lawns, Heavy Soil:
0.2
Flat<2%.........1....................................................................................
0.25
Average2 to 7%..................................................................................
0.35
Steep>7%......... :.....................................................................
...........
MAY 1984 3-4 DESIGN CRITERIA
3.1.7 Time of Concentration
In order to use the Rainfall Intensity Duration Curve, the time of concentration must be
known. This can be determined either by the following equation or the "Overland Tima `
Flow Curves" from the Urban Storm Drainage Criteria Manual, included in this report
Figure 3-2).
Tc =1.87 (1.1 - CC,) D 12
So
Where Tc = Time of Concentration, minutes
S = Slope of Basin, %
C = Rational Method Runoff Coefficient
D = Length of Basin, feet
Cf = Frequency Adjustment Factor
Time of concentration calculations should reflect channel and storm sewer velocities as well
as overland flow times.
3.1.8 Adjustment for Infrequent Storms
The preceding variables are based on the initial storm, that is, the two to ten year storms. For
storms with higher intensities an adjustment of the runoff coefficient is required because of
the lessening amount of infiltration, depression retention, and other losses that have a
proportionally smaller effect on storm runoff.
These frequency adjustment factors are found in Table 3-4. -
Table 3-4
RATIONAL METHOD FREQUENCY ADJUSTMENT FACTORS
Storm Return Period Frequency Factor
a
(years) C,i
2 to 10 1.00
11 to 25 1.10
i$ -
26 to 00
51 to 100 1.25
"..$
Note: The product of C times C, shall not exceed 1.00
3.2 Analysis Methodology
The methods presented in this section will be instituted for use in the determination arid/or verification
of runoff at specific design points in the drainage system. These methods are (1), the .Rational Method
and (2) the Colorado Urban Hydrograph Procedure (CUHP). Other computer methods, such as
SWMM, STORM, and HEC-1 are allowable if results are not radically different than these two. Where
applicable, drainage systems proposed for construction should provide the minimum protection as
determined by the methodology so mentioned above.
3.2.1 Rational Method
For drainage basins of 200 acres or less, the runoff may be calculated by the Rational
Method, which is essentially the following equation:
Q = CfCIA
Where Q = Flow Quantity, cfs
A = Total Area of Basin, acres
Cf = Storm Frequency Adjustment Factor (See Section 3.1.8)
C = Runoff Coefficient (See Section 3.1.6)
I = Rainfall Intensity, inches per hour (See Section 3.1.4)
3.2.2 Colorado Urban Hydrograph Procedure
For basins larger than 200 acres, the design storm runoff should be analyzed by deriving
synthetic unit hydrographs. It is recommended that the Colorado Urban Hydrograph
_ Procedure be used for such ana!ysis. This procedure is detailed in the Urban Storm Dra; 'e
Criteria Manual, Volume 1, Section 4.
MAY 1984 3-5 DESIGN CRITERIA
No Text
APPENDIX HI
Floodplain exhibit
N
arimer Count 1
lEA NOT INCLUD D
ZONE A
COMMUNITY —PANEL NO.
.080102 0004, C
MAP REVISEDMAR.1891996
LEMAYDS
PROF
ILE BASELINE
T MAGN01
STREET
El v 4334
ILI
APPENDIX IV
Stuffer Envelope
Grading Plan
Drainage and Erosion Control Plan
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