HomeMy WebLinkAbout20041995.tiff FINAL DRAINAGE INVESTIGATION
EROSION CONTROL REPORT
for
CATTAIL CREEK - P. U. D.
to be located on
Lot C of the Recorded Exemption No. RE - 2637
WELD COUNTY, COLORADO
Prepared for:
Cattail ('reek, LLC
P. O. Box 68
Windsor, Colorado 8055(
May 2004
—
Project No. CR1) - 431 - (12
Prepared by:
MESSNER_Engineering Inc____ _
150 Fast 29' Street. Suite 270 Loveland Colorado 80538-2765 Telephone ;970) 663-2221
2004-1995
Eill2,2RIEE
Engineering, Inc.
Project No. GRD - 431 - 02
May 14, 2004
John Shepardson
Cattail Creek, LLC
P. O. Box 68
Windsor, Colorado 80550
Dear Mr. Shepardson,
The enclosed report represents the results of the Final Drainage Investigation and Erosion Control
Report for the proposed "Cattail Creek - P.U.D." to be located on Lot C of the Recorded Exemption
No. RE-2637 in Weld County, Colorado.
This investigation was based upon the proposed site development plan; on-site observation; and
available topographic information. The investigation was performed according to the criteria
established by Weld County.
Thank you for the opportunity to be of service. If you should have any questions, please feel free to
contact this office.
Respectfully Submitted,
MESSNER Engineering, Inc.
Cameron W. Knapp, Civil Engineer
"I hereby state that this final report (plan) for the "Cattail Creek- P. U. D., Lot C of the Recorded
Exemption RE-2637 in Weld County, Colorado " was prepared by me or under my direct
supervision for the owners thereof and meets or exceeds the criteria established by Weld County."
F G
Dennis R.Vl ner :
Registered frtfa gsjonal t'it'er
State of ColoWIt(2,61.09/
Civil Engineering Consultants
150 E. 29th Street, Suite 270 Loveland, Colorado 80538 (970) 663-2221
TABLE OF CONTENTS
Description Page
LE I fER OF TRANSMITTAL
TABLE OF CONTENTS ii & iii
I GENERAL LOCATION AND DESCRIPTION
A. Location 1
B. Description of Property 1
II DRAINAGE BASINS and SUB-BASINS
A. Major Basin Description 1
B. Sub-Basin Description 2
III DRAINAGE DESIGN CRITERIA
_ A. Development Regulations and Criteria Reference 2
B. Development Constraints 2
C. Hydrologic Criteria 2
D. Hydraulic Criteria 3
IV DRAINAGE FACILITY DESIGN
A. General Concept 4
B. Specific Detail 4
V EROSION & STORMWATER QUALITY CONTROL
A. General Concept 5
VI CONCLUSIONS
A. Compliance with Standards 7
B. Drainage Concept 7
C. Recommendations 7
VII REFERENCES 8
ll
TABLE OF CONTENTS (CONTINUED):
EXHIBITS
Vicinity Map
F.I.R.M. Community Panel #080266-0475-C
Existing Conditions Drainage Exhibit
Proposed Conditions Drainage Exhibit
Grading, Drainage, and Erosion Control Plan
APPENDIX I
Drainage Summary
Drainage Calculations
APPENDIX II
Charts, Graphs, Figures and Details
iii
I. General Location and Description:
A. Location
1. The proposed Cattail Creek, P.U.D. is located in Section 9, Township 6 North, Range 66
West of the 6th P.M. in Weld County, Colorado.
2. The site is specifically located on the north side of Weld County Road 70, between Weld
County Roads 29 and 31. (Refer to the included Vicinity Map.)
3. The site is bordered on the south by Weld County Road 70. An existing concrete lined
irrigation channel makes up the western most boundary of the development. Mother
irrigation/drainage ditch outlines the site to the north and east. Drainage from this ditch is
passed beneath Weld County Road 70 via a box culvert, and continues to the south.
B. Description of property
1. The Cattail Creek, P.U.D. property consists of approximately 161.34 acres, however, the
area to be developed makes up only approximately 37 acres.
a. The majority of the property is currently used as irrigated farm land.
2. The "Soil Survey of Weld County, Colorado"prepared by the U.S. Department of
Agriculture, Soil Conservation Service, indicated that the surface soils consist primarily of
"Kim Loam and Olney Fine Sandy Loam."
a. The Kim soil type is described as a deep, well-drained soil found on alluvium fans
and formed from mixed eolian deposits and parent sediment. The "Soil Survey"
identifies the surface runoff potential as rapid, and the hazard of erosion as moderate.
b. The soil typical of the Olney series is described as a deep, well-drained soil that
formed in mixed outwash deposits. The "Soil Survey" identifies the surface runoff
potential as medium and the hazard of erosion as low.
3. The site is generally considered mildly sloped, with slopes ranging from 0.50% to 3%.
4. The proposed development will consist of eight (8) estate type residential lots, each 4
acres in size. A proposed 24-foot wide asphalt cul de sac called will provide access to the
development from Weld County Road 70.
II. Drainage Basins and Sub-basins:
A. Major Basin Description
1. The site does not lie within a locally designated major drainage basin.
1
2. The United State Geological Survey identifies the subject area as part of the Cache La
Poudre River Basin.
3. The eastern edge of the site is located within a 100-year Flood Zone as identified on the
Federal Emergency Management Agency, Community Panel No. 080266-0475-C, dated
September 28, 1982. Neither the buildable portions of the residential lots or the proposed
roadway are located within the designated flood way.
B. Sub-basin Description
1. The site is identified on the Existing Drainage Exhibit as Sub-Basin 'A' and comprises
approximately 36.92 acres. The sub-basin produces 3.41 c.f.s. during the 5-year storm and
30.03 c.fs. during the 100-year storm. Surface runoff drains across the property from west
to east as sheet flow before spilling into the existing irrigation/drainage ditch that outlines the
eastern edge of the site.
2. A box culvert bridge is located at the crossing of Weld County Road 70 and the ditch.
Flow passes to the south side of the road and is carried in the ditch further south where it
becomes the Greeley No. 2 Canal. Flow ultimately is conveyed to the Cache La Poudre
River.
3. The site is self-contained from off-site runoff. Weld County 70 prevents stormwater from
intruding from the south, and the channels prevent intrusion from the west and north sides.
III. Drainage Design Criteria:
A. Development Regulations and Criteria Reference
1. Drainage design requirements from the Weld County Code (Section 24) was utilized.
Since Weld County does not publish technical data or storm drainage design manuals, certain
technical and design criteria comes from the Urban Storm Drainage Criteria Manual.
B. Development Constraints
1. The historic drainage pattern of the site will be maintained. The proposed grading will be
conducted only in the areas of the proposed roadway and the residential home sites. The
majority of the site will not be impacted by earthwork.
2. The drainage impact of this site will not adversely affect roads or utilities.
C. Hydrological Criteria
1. The Rational Method was used for determining peak flows at various concentration
points since all sub-basins were less than 160 acres in size.
a. The worksheets used to determine the peak runoff rates, (see Drainage
2
Calculations in Appendix I of this report), come from the Urban Storm Drainage
Manual.
b. The Hydrological Classifications for the on-site soils are Type 'B'.
c. Table RO-3 of the Urban Storm Drainage Manual contains the recommended
percentage of imperviousness values used for various land use or surface
characteristics. However, due to the large size of the residential lots, an overall
imperviousness was not used for areas considered "residential" as is the case for more
urban residential conditions. Instead, the residential lots were broken down into roof
area, (based on 3,300 square feet for each home), landscaping, (the buildable portion
of each lot), and remainder of each of the lots, (non-buildable or set back portions),
was considered as"undeveloped" area having the same imperviousness as in the
historic conditions.
d. The "computed", rather than the "regional" time of concentration calculation was
used for the proposed conditions, as computed by the urban storm drainage
worksheets. This is due to the very low density of the proposed development, which
does not resemble typical urban conditions implied by the Regional Tc that is also
calculated on the worksheets.
2. Section 24 of the Weld County Code calls for the initial and major storm design
frequencies of 5 and 100-years.
a. The peak runoff rates for the property and off-site area were calculated using the 5
and 100-year rainfall intensities.
b. The Rainfall Intensity-Duration-Frequency Curve for Windsor, Colorado was
utilized.
3. The contents in the tables, charts, and figures presented in this report, come from the
Urban Storm Drainage Criteria Manual. These diagrams facilitated in the drainage design
calculations.
D. Hydraulic Criteria
1. The design and sizing of roadway and driveway culverts will be done at the time of the
final drainage investigation.
a. The proposed roadway culvert and driveway culverts will be designed using
Corrugated Metal Pipe (CMP). CMP is considered to have a Mannings 'n' value of
0.024.
b. Culvert capacities will be based on the 100-year design frequency.
c. The maximum allowable headwater to diameter ratio used for the 100-year storm
will be 1.5.
3
d. The minium diameter for driveway culverts is considered to be 15-inches and all
culverts less than 42-inches in diameter shall be installed with flared end sections.
Culverts greater than 42-inches will require a concrete headwall and wingwalls.
2. The sizing of roadside ditches and drainage swales will also be done at the time of the final
drainage investigation using the Urban Storm Drainage Criteria worksheet program for sizing
channels.
a. Proposed grassed lined swales and ditches will have capacity to convey the 100-
year peak flow rates with either 1-foot or 133% of the peak flow rate as freeboard.
b. The recommended Manning value by the Urban Storm Drainage Criteria Manual is
0.035 for grassed lined channels with less than 3-feet of flow depth.
IV. Drainage Facility Design:
A. General Concept
1. Surface runoff from the proposed drive area and residential lots will flow overland and
empty into the adjacent irrigation/drainage ditch along the eastern edge of the site in much
the same pattern as during the existing conditions.
B. Specific Details
1. The Proposed Drainage Exhibit shows the proposed drainage pattern of the site divided
into five (5) separate sub-basins. This is a result of surface runoff being impeded from
flowing east to west across the site due to the proposed paved cul de sac.
a. At a low point in the roadway, a culvert will be placed to pass flow from the west
side of the road into a drainage swale on the east side of the road.
b. The proposed drainage swale will extend east within the easement between Lots 2
& 3 until reaching the eastern edge of the site and discharging down a proposed
riprap rundown into the existing irrigation/drainage ditch.
c. A culvert at the crossing of Weld County Road 70 and the proposed cul de sac will
be required to maintain flow in the existing roadside ditch, as well as passing runoff
from the southwest corner of the site to the east side of the cul de sac.
2. Sub-Basin 'A' makes up 13.17 acres of the northern portion of the site that will continue
to drain as sheet flow in the historic pattern from west to east before emptying into the
irrigation/drainage ditch. The peak runoff rates produced by the sub-basin are 1.40 cis.
during the 5-year storm and 12.28 c.f.s. during the 100-year storm.
3. Sub-Basin `B' comprises a pocket of 3.45 acres that lies east of the cul de sac and north
of the proposed drainage swale. Runoff produced by Sub-Basin `B' flow overland until being
4
intercepted by the drainage swale. Flow is then carried east within the drainage swale and
discharges into the existing irrigation/drainage ditch. The 5-year and 100-year peak runoff
rates are 1.25 c.fs. and 6.97 c.f.s.
4. The west side of the site that will drain to the culvert crossing at the low point in the cul
_ de sac is identified as Sub-Basin 'C'. This sub-basin contains 8.10 acres from area situated
between the west edge of the site and the crown of the proposed roadway. Surface runoff
will flow to the east before being captured by the roadside ditch of the proposed cul de sac.
The ditch will direct flow to a low point where a proposed CMP culvert will be installed.
The 5-year peak runoff rate for the sub-basin is 1.61 c.fs. and the 100-year peak runoff rate
is 11.13 c.fs.
5. Sub-Basin 'D' contains 3.66 acres from the southwest corner of the site. This area drains
from west to east until reaching the roadside ditch of the proposed cul de sac. The roadside
ditch then breaks south towards Weld County Road 70 where a second proposed culvert will
be installed. Flow will pass through the culvert to the east side of the road intersection and
into the existing roadside ditch along the north side of Weld County Road 70. The roadside
ditch empties into the irrigation/drainage ditch via a 36" diameter CMP culvert at the
southeast corner of the property. The peak runoff rates generated by the sub-basin are 0.66
c.fs. and 4.54 c.f.s. during the 5-year and 100-year storm events.
6. Sub-Basin `E' represents 8.54 acres located on the east side of the proposed roadway that
_ will drain overland in the historic fashion from west to east and spill into the existing
irrigation/drainage ditch. During the 5-year and 100-year storms, Sub-Basin `E' produces
peak flow rates of 1.15 c.f.s. and 9.17 c.f.s.
7. Driveway culverts will be required to maintain flow in the roadside ditches. The culverts
will be CMP and have flared-end sections. The culverts will be individually sized at the time
of the final drainage investigation and the minium culvert size will be 15-inches in diameter.
8. The development of the site will result in an increase of the overall imperviousness from
2.39% to 5.04%. (See Drainage Summary in Appendix I of this report.)
a. The slight increase in imperviousness will produce a small increase in runoff during
the minor and major storm events. The 5-year peak runoff rate will increase by 2.05
c.fs. and the 100-year peak runoff rate will increase by 4.06 c.fs.
b. The slight increase in stormwater runoff produced by the proposed development
will be negligible to downstream facilities. Therefore, detention of stormwater for the
proposed development is not recommended.
V. Erosion and Stormwater Quality Control:
A. General Concept
1. Erosion control considerations have been made based upon the short term, during
5
construction activities, and the long term, when development of the subdivision is complete.
2. The recommended short term erosion control method to be incorporated into the
construction requirements for the project is the placing of sediment control devices such as
"Straw Bale Inlet Filters", "Silt Fencing", and "Straw Bale Dikes". These are being
_ recommended in order to prevent debris and sediment from flowing from the areas disturbed
by construction activities onsite to the adjacent irrigation/drainage ditch.
a. Silt fencing is to be placed on downstream side of areas disturbed by individual lot
grading and home construction.
_ b. Straw Bale Inlet Filters are to be place at the upstream end of all roadway and
driveway culverts.
c. Straw Bale Dikes shall be installed at 125-150 foot intervals in the drainage swale
and roadside ditches.
3. The long term measures incorporated to eliminate erosion are the anticipated methods and
materials to be used to provide the ground surface covering at the driveways and the
landscaped areas. The residential structures and surrounding hard-surfaced areas will provide
a deterrent to erosion. The establishment of pasture, lawns and the combination of landscape
plantings and ground covers will aid in deterring erosion.
a. The proposed drainage swales and roadside ditches, (in addition to any areas
disturbed by grading), will be revegetated with a native seed mixture. The use of
grass-lined swales is considered a Best Management Practice (BMP) for removal of
low levels of suspended solids by Volume III of the Urban Storm Drainage Criteria
Manual. The long length, mild slope, and low velocities during more frequent smaller
storm events will aid is settling sediment before exiting the site.
b. The long overland flow path from areas on the east side of the cul de sac to the
existing irrigation/drainage ditch will act as a"buffer" to promote filtration,
infiltration, and settling of sediment to reduce runoff pollutants.
c. The riprap rundown channel constructed at the end of the drainage swale will
prevent long term scouring along the existing bank of the irrigation/drainage ditch.
d. Placement of riprap at the downstream flared end sections of the proposed culverts
will be required if exiting velocities exceed 7.0 feet per second. Rip rap will slow
runoff velocity and help prevent scouring and undercutting at the downstream ends of
the culverts.
4. Wind erosion control measures have not been recommended for the site. It is anticipated
that the disturbed area will be open and subject to wind action for an extremely short time. If
blowing dust is a problem, a combination of surface roughening and water application is to be
used to control the dust.
6
5. The Owner shall warrant that the measures shown on the approved erosion and sediment
control plan are properly constructed, installed, and are free from defective material and/or
workmanship, for as long as construction on the site continues, or said measures are
necessary to protect against erosion and sediment transport.
6. Proposed erosion control measures conform to the recommendations of Volume III of
the Urban Storm Drainage Criteria Manual, and generally accepted erosion control
procedures.
VI. Conclusions:
A. Compliance with Standards
1. All drainage design conforms to the requirements of Weld County Code Section 24.
2. Proposed erosion control and stormwater quality measures conform to the
— recommendations presented in Volume III of the Urban Storm Drainage Criteria Manual and
generally accepted procedures.
B. Drainage Concept
1. This sketch plan drainage report for the Cattail Creek, P.U.D. is considered preliminary.
The final drainage report will update these concepts and present the final design details for
the necessary drainage improvements.
2. The developed areas of the site are not located within the designated flood way.
3. The historic downstream point of concentration for the development will remain the box
culvert crossing at Weld County Road 70. The ultimate point of discharge for the site is the
Cache La Poudre River.
C. Recommendations
I. A proposed roadway culvert will be installed at the intersection of Weld County Road 70
and the proposed cul de sac.
2. A proposed CMP culvert will be required at the low point on the cul de sac to pass runoff
to the east side of the road.
3. A proposed grass lined drainage swale will route flow from the downstream end of the
proposed culvert to the existing irrigation/drainage ditch on the eastern edge of the site.
4. Driveway culverts will be necessary to pass flow in roadside ditches beneath individual
driveways.
5. Erosion and stormwater control measures will be incorporated during the construction
7
activities to deter erosion and prevent sediment from being deposited into the adjacent ditch.
6. The development of the property will result in such a small increase of runoff that
stormwater detention is not recommended.
VII. References:
A. "Urban Storm Drainage Criteria Manual", Updated 2001.
B. "Weld County Code, Section 24-7-110", Current Revision.
_ C. "Soil Survey of Southern Weld County Area, Colorado", United States Department of
Agriculture, September 1980.
—
8
EXHIBITS
_ .
CATTAIL CREEK , P . U . D .
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VICINITY MAP
- (NOT TO SCALE)
LOT C of the AMENDED RECORDED EXEMPTION No. 2637
WELD COUNTY, COLORADO
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RING
To determine if flood Insurance is available in this community
r conct your Insurance agent,or call the National Flood Insurance
\ t , Program at(800) 6386620.
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GREAT WESTERN 1 /GATES
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COMMUNITY-PANEL NUMBER
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'` — ‘ #4 Basin 'B'^ .Design Point, Basin Number
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Existing 36"
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CMP Culvert Roadside Ditch(typ) Q5 c.f.s. 2 of 2
Drainage Report
contains oversized
" Grading , Drainage ,
,„ and Erosion Control
Plan " Map
Please See original
File
APPENDIX I
DRAINAGE S UMMARY
- DRAINAGE CALCULATIONS
DRAINAGE SUMMARY
EXISTING CONDITIONS:
Sub-Basin Area Imper. QS Q10D
(acres) (%) (c.fs.) (c.fs.)
'A' 36.92 2.39 3.41 30.03
Sum: 36.92 Sum: 3.41 30.03
PROPOSED CONDITIONS:
Sub-Basin Area Imper. Qs Qtoo
(acres) (%) (c.fs.) (c.fs.)
'A' 13.17 2.59 1.40 2.28
B' 3.45 11.73 1.25 6.97
'C' 8.10 6.47 1.61 11.13
D' 3.66 6.52 0.66 4.54
'E' 8.54 4.15 1.15 9.17
Sum: 36.92 Sum: 6.07 34.09
Area-Weighting for Runoff Coefficient Calculation
Project Title: CATTAIL CREEK, P.U.D.
Catchment ID: EXISTING SUB-BASIN 'A'
Illustration
Ses1
LEGEND:
Plow Direction
es
SaSig
Subaaa3 Catehm�
Bormday
Instructions: For each catchment subarea,enter values for A and C.
Subarea Area Runoff Product
ID acres Coeff.
A C' CA
input input input output
Undev. 36.54 2.00 73.08
Gravel 0.38 40.00 15.20
sum: 36.92 sum: 88.28
Area-Weighted Runoff Coefficient(sum CAlsum A)= 2.39
"See sheet"Design Info"for inperviousness-based runoff coefficient values.
Messner Engineering, Inc.
CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: EXISTING SUB-BASIN'A' (5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'A'
Area= 36.92 Acres
Percent Imperviousness= 2.39 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(inch/hr)=C1 •P1 /(C2+Td)"C3
Design Storm Return Period, Tr= 5 years (input return period for design storm)
Cl = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 1.30 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.08
Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.08
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
•-
-------
overland LEGEND
Reach 1 Row
Reach 2 O 8le6
Flow Direction
E
Reach 3 Catchment
He adary
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0150 945 0.08 0.32 49.38
1 0.0029 1,300 15.00 0.81 26.82
2
3
4
5
Sum 2,245 Computed Tc= 76.21
Regional Tc= 22.47
N.
Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I= 1.12 inch/hr Rainfall Intensity at Tc, I= 2.40 inch/hr
Peak Flowrate, Qp= 3.41 cfs Peak Flowrate, Qp= 7.35 cfs
Messner Engineering,Inc.
_ CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: EXISTING SUB-BASIN'A' (100-yr Storm)
—
I. Catchment Hydrologic Data
Catchment ID= 'A'
Area= 36.92 Acres
Percent Imperviousness= 2.39 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(inch/hr)=Cl *P1 /(C2+Td)"C3
— Design Storm Return Period,Tr= 100 years (input return period for design storm)
C1 = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 2.60 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
—
Runoff Coefficient, C= 0.36
Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.08
— Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired,or leave blank to accept calculated C-5.)
Illustration
^ '-------
overland LEGEND
Reach 1 flow
Reach 2• O Beginning
—
• Flow Direction
Beach 3 Catchment
._ Bo'e+darr
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas&
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
— Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 ] 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
—
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
—
Overland 0.0150 945 0.08 0.32 49.38
1 0.0029 1,300 15.00 0.81 26.82
2
—
3
4
. 5
Sum 2,245 Computed Tc= 76.21
— Regional Tc= 22.47
IV.
....„ Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I= 2.23 inch/hr Rainfall Intensity at Tc, I = 4.81 inch/hr
Peak Flowrate, Qp= 30.03 cfs Peak Flowrate, Qp= 64.68 cfs
— Messner Engineering,Inc.
Area-Weighting for Runoff Coefficient Calculation
Project Title: CATTAIL CREEK,P.U.D.
Catchment ID: PROPOSED SUB-BASIN 'A'
Illustration
S e.l-
LEGEND:
Flow Direction
e9?S
Catch
Sidman 3 n an
Boundary
Instructions: For each catchment subarea,enter values for A and C.
Subarea Area Runoff Product
ID acres Coeff.
A C' CA
input input input output
Undev. 10.31 2.00 20.62
Gravel 0.00 40.00 0.00
Asphalt 0.00 100.00 0.00
Landscape 2.71 0.00 0.00
Roof 0.15 90.00 13.50
Sum: 13.17 sum: 34.12
Area-Weighted Runoff Coefficient(sum CA/sum A)= 2.59
*See sheet"Design Info"for inperviousness-based runoff coefficient values.
Messner Engineering, Inc.
_ CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'A' (5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'A'
Area= 13.17 Acres
Percent Imperviousness= 2.59 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(inch/hr)=C1 *P1 /(C2+Td)^C3
Design Storm Return Period, Tr= 5 years (input return period for design storm)
C1 = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 1.30 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.08
Overide Runoff Coefficient, C= (enter an overide C value if desired,or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.08
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
overland EL GEND
Reach 1 flow
Reach2� O Beeming
• flaw Direction
Reach 3 Catchment
Bsaadary
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
_ Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
NR ft C-5 fps minutes
input input output input output output
Overland 0.0150 945 0.08 0.32 49.35
1 0.0030 660 15.00 0.82 13.39
2
3
4
5
Sum 1,605 Computed Tc= 62.74
Regional Tc= 18.92
IV.
Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I = 1.27 inch/hr Rainfall Intensity at Tc, I= 2.63 inch/hr
Peak Flowrate, Qp= 1.40 cfs Peak Flowrate, Op= 2.89 cfs
.— Messner Engineering,Inc.
_ CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN 'A' (100-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'A
Area= 13.17 Acres
Percent Imperviousness= 259 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(inch/hr)=C1 •P1 /(C2+Td)"C3
Design Storm Return Period,Tr= 100 years (input return period for design storm)
C1 = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 2.60 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.37
Overide Runoff Coefficient, C= (enter an overide C value if desired,or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.08
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
overland LEGEND
Reach 1 flow
Reach 2. O B6
Flow Direction
� E
Reach 3 Catchment
.... Baardarr
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas&
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
_ Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V TI
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0150 945 0.08 0.32 49.35
1 0.0030 660 15.00 0.82 13.39
2
3
4
5
Sum 1,605 Computed Tc= 62.74
Regional Tc= 18.92
IV.
.-. Peak Runoff Prediction using Computed Tc edlction using Regional Tc
Rainfall Intensity at Tc, I= 2.55 inch/hr Rainfall Intensity at Tc, I= 5.26 inch/hr
Peak Flowrate, Qp= 12.28 cfs Peak Flowrate, Qp= 25.36 cfs
.� Messner Engineering,Inc.
Area-Weighting for Runoff Coefficient Calculation
Project Title: CATTAIL CREEK, P.U.D.
Catchment ID: PROPOSED SUB-BASIN 'B'
Illustration
psi
S
LEGEND:
Flow Direction
e6
Careaet
Saban 3 Boundary
Instructions: For each catchment subarea,enter values for A and C.
Subarea Area Runoff Product
ID acres Coeff.
�-. A C* CA
input input input output
Undev. 1.03 2.00 2.06
Gravel 0.08 40.00 3.20
Asphalt 0.28 100.00 28.00
Landscape 1.98 0.00 0.00
Roof 0.08 90.00 7.20
Sum: 3.45 Sum: 40.46
Area-Weighted Runoff Coefficient(sum CA/sum A)= 11.73
*See sheet"Design Info"for inperviousness-based runoff coefficient values.
Messner Engineering, Inc.
_ CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
.-.
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'B'(5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'B'
Area= 3.45 Acres
Percent Imperviousness= 11.73 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(Inch/hr)=Cl *P1 /(C2+Td)AC3
Design Storm Return Period,Tr= 5 years (input return period for design storm)
Cl = 28.50 (input the value of Cl)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 1.30 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.15
Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.15
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
overlaid LEGEND
Reach 1 flay
Reach • O Bed
Fin Direction
♦ E
Reach 3 Catchment
Boundary
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0450 50 0.15 0.11 7.40
1 0.0075 1,100 15.00 1.30 14.11
2
3
4
5
Sum 1,150 Computed Tc= 21.51
Regional Tc= 16.39
IV.
Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I= 2.46 inch/hr Rainfall Intensity at Tc, I= 2.83 inch/hr
Peak Flowrate, Op= 1.25 cfs Peak Flowrate, Qp= 1.44 cfs
Messner Engineering,Inc.
_ CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'B'(100-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'B'
Area= 3.45 Acres
Percent Imperviousness= 11.73 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(Inch/hr)=Cl "P1 /(C2+Td)*C3
Design Storm Return Period, Tr= 100 years (input return period for design storm)
C1 = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of CS)
P1= 2.60 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.41
Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.15
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired,or leave blank to accept calculated C-5.)
Illustration
LEGEND
Reach
Reach 2. O > s
Flow Direction
� E
Reach 3 Catchment Hsaadary
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas&
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Row)
Conveyance 2.5 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0450 50 0.15 0.11 7.40
1 0.0075 1,100 15.00 1.30 14.11
2
3
4
5
Sum 1,150 Computed Tc= 21.51
Regional Tc= 16.39
IV.
,.., Peak Runoff Prediction using Computed Tc edictlon using Regional Tc
Rainfall Marty at Tc, I= 4.92 inch/hr Rainfall Intensity at Tc, I= 5.66 inch/hr
Peak Flowrate, Op= 6.97 cfs Peak Flowrate, Qp= 8.02 cfs
�. Messner Engineering,Inc.
Area-Weighting for Runoff Coefficient Calculation
Project Title: CATTAIL CREEK,P.U.D.
Catchment ID: PROPOSED SUB-BASIN 'C'
Illustration
es}
S
LEGEND:
Flow Direction
es
S CatcLmmR
_ Sabana 3 Botmdary
Instructions: For each catchment subarea,enter values for A and C.
Subarea Area Runoff Product
ID acres Coeff.
.-- A C" CA
input input input output
Undev. 3.84 2.00 7.68
Gravel 0.08 40.00 3.20
Asphalt 0.28 100.00 28.00
Landscape 3.75 0.00 0.00
Roof 0.15 90.00 13.50
sum: 8.10 sum: 52.38
Area-Weighted Runoff Coefficient(sum CA/sum A)= 6.47
*See sheet"Design Info"for inperviousness-based runoff coefficient values.
Messner Engineering, Inc.
_ CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'C' (5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'C'
Area= 8.10 Acres
Percent Imperviousness= 6.47 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(inch/hr)=C1 *P1 /(C2+Td)AC3
Design Storm Return Period,Tr= 5 years (input return period for design storm)
C1 = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 1.30 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.11
Overide Runoff Coefficient, C= (enter an overide C value if desired,or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.11
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
overlaid LEGEND
Reach 1 gay
Reach 2. O Beginning
• blow Martha
et-
Reach 3 Catchment
13o'Jary
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas&
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance I 2.5 I 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0200 425 0.11 0.24 29.27
1 0.0050 535 15.00 1.06 8.41
2
3
4
5
Sum 960 Computed Tc= 37.68
Regional Tc= 15.33
IV.
.� Peak Runoff Prediction using Computed Tc edlctlon using Regional Tc
Rainfall Intensity at Tc, I= 1.78 inch/hr Rainfall Intensity at Tc, I= 2.92 inch/hr
Peak Flowrate, Qp= 1.61 cfs Peak Flowrate, Qp= 2.64 cfs
Messner Engineering,Inc.
CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Tide: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'C' (100-yr Storm)
I. Catchment Hydrologic Data •
Catchment ID= 'C'
Area= 8.10 Acres
Percent Imperviousness= 6.47 %
NRCS Soil Type= B A, B, C,or D
II. Rainfall Information I(inch/hr)=C1 *P1/(C2+Td)"C3
Design Storm Return Period,Tr= 100 years (input return period for design storm)
Cl = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 2.60 inches (input one-hr precipitation—see Sheet"Design Info")
M. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.39
Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.11
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired,or leave blank to accept calculated C-5.)
Illustration
ovedand LEGEND
Reach 1 Raw
Reach 2. O DeSbudaR
FUN Direction
• F
Reach 3 Catchment
Bandar,-
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0200 425 0.11 0.24 29.27
1 0.0050 535 15.00 1.06 8.41
2
3
4
5
Sum 960 Computed Tc= 37.68
Regional Tc= 15.33
IV.
Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I= 3.55 inch/hr Rainfall Intensity at To, I = 5.84 inch/hr
Peak Flowrate, Qp= 11.13 cfs Peak Flowrate, Qp= 18.30 cfs
Messner Engineering,Inc.
Area-Weighting for Runoff Coefficient Calculation
Project Title: CATTAIL CREEK, P.U.D.
Catchment ID: PROPOSED SUB-BASIN 'D'
Illustration
see}
LEGEND:
Flow Direction
ee 1 +
S&gil Cardmend
Sa naa 3
Boundary
Instructions: For each catchment subarea,enter values for A and C.
Subarea Area Runoff Product
ID acres Coeff.
A C* CA
input input input output
Undev. 1.94 2.00 3.88
Gravel 0.17 40.00 6.80
Asphalt 0.06 100.00 6.00
Landscape 1.41 0.00 0.00
Roof 0.08 90.00 7.20
sum: 3.66 sum: 23.88
Area-Weighted Runoff Coefficient(sum CAlsum A)= 6.52
"See sheet"Design Info"for inperviousness-based runoff coefficient values.
Messner Engineering, Inc.
CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'D'(5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID=
Area= 3.66 Acres
Percent Imperviousness= 6.52 %
NRCS Soil Type= B A, 8, C,or D
II. Rainfall Information I(Inch/hr)=C1 "P1 /(C2+Td)^C3
Design Storm Return Period,Tr= 5 years (input return period for design storm)
C1 = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 1.30 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.11
Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.11
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired,or leave blank to accept calculated C-5.)
Illustration
�--
overland LEGEND
Reach 1 flow
Reseh2. O Bed
Flow Direction
♦ f
Reach 3 Catchment
Bo aaary
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swain
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
_ input input output input output output
Overland 0.0100 600 0.11 0.23 43.70
1 0.0150 75 15.00 1.84 0.68
2
3
4
5
Sum 675 Computed Tc= 44.38
Regional Tc= 13.75
IV.
Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I = 1.60 inch/hr Rainfall Intensity at Tc, I= 3.07 inch/hr
Peak Flowrate, Qp= 0.66 cfs Peak Flowrate, Qp= 1.26 cfs
Messner Engineering,Inc.
CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'D'(100-yr Storm)
—
I. Catchment Hydrologic Data
_, Catchment ID= 'D'
Area= 3.66 Acres
Percent Imperviousness= 6.52 %
NRCS Soil Type= B A, B,C, or D
II. Rainfall Information I(inch/hr)=C1 *P1 /(C2+Td)AC3
— Design Storm Return Period,Tr= 100 years (input return period for design storm)
Cl = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
— P1= 2.60 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
".. Runoff Coefficient, C= 0.39
Overide Runoff Coefficient, C= (enter an overide C value if desired,or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.11
— Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
overland LEGEND
Reach I flow
Reach2• .O Beglaning
—
Flow Direction
F
Reach 3 Catchment
Bna&a:'r
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
— Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
_
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
—
Overland 0.0100 600 0.11 0.23 43.70
1 0.0150 75 15.00 1.84 0.68
2
3
4
5
Sum 675 Computed Tc= 44.38
— Regional Tc= 13.75
IV.
4.—. Peak Runoff Prediction using Computed Tc edlction using Regional Tc
Rainfall Intensity at Tc, I= 3.20 inch/hr Rainfall Intensity at Tc, I= 6.15 inch/hr
— Peak Flowrate, Op= 4.54 cfs Peak Flowrate, Qp= 8.70 cfs
— Messner Engineering,Inc.
Area-Weighting for Runoff Coefficient Calculation
Project Title: CATTAIL CREEK,P.U.D.
Catchment ID: PROPOSED SUB-BASIN 'E'
Illustration
Seal
�. LEGEND:
Flow Direction
lea
5 Catchment
Subarea 3 Boundary
Instructions: For each catchment subarea,enter values for A and C.
Subarea Area Runoff Product
_ ID acres Coeff.
A C* CA
input input input output
Undev. 4.55 2.00 9.10
Gravel 0.17 40.00 6.80
Asphalt 0.06 100.00 6.00
Landscape 3.61 0.00 0.00
Roof 0.15 90.00 13.50
sum: 8.54 Sum: 35.40
Area-Weighted Runoff Coefficient(sum CA/sum A)= 4.15
*See sheet"Design Info"for inperviousness-based runoff coefficient values.
Messner Engineering, Inc.
CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'E'(5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= E'
Area= 8.54 Acres
Percent Imperviousness= 4.15 %
NRCS Soil Type= B A, B, C, or D
Ii. Rainfall Information I(Inch/hr)=C1 *P1/(C2+Td)AC3
Design Storm Return Period,Tr= 5 years (input return period for design storm)
C1 = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 1.30 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.09
Overide Runoff Coefficient, C= (enter an overide C value if desired, or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, C-5= 0.09
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired,or leave blank to accept calculated C-5.)
Illustration
- /"-
�--------�
overland LEGEND
Reach 1 liar
Reach 2• o B
Flow Direction
� E
Reach 3 Catchment
Ha.ndary
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas 8
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
_ Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0125 700 0.09 0.26 44.64
1 0.110.15 425 15.00 0.89 7.98
2
3
4
5
Sum 1,125 Computed Tc= 52.62
—� Regional Tc= 16.25
IV.
Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I = 1.43 inch/hr Rainfall Intensity at Tc, I= 2.84 inch/hr
Peak Flowrate, Qp= 1.15 cfs Peak Flowrate, Qp= 2.28 cfs
- Messner Engineering,Inc.
CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD
Project Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'E'(100-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'E'
Area= 8.54 Acres
Percent Imperviousness= 4.15 %
NRCS Soil Type= B A, B, C, or D
II. Rainfall Information I(Inch/hr)=Cl *P1 /(C2+Td)"C3
Design Storm Return Period,Tr= 100 years (input return period for design storm)
Cl = 28.50 (input the value of C1)
C2= 10.00 (input the value of C2)
C3= 0.786 (input the value of C3)
P1= 2.60 inches (input one-hr precipitation—see Sheet"Design Info")
III. Analysis of Flow Time(Time of Concentration)for a Catchment
Runoff Coefficient, C= 0.37
Overide Runoff Coefficient, C= (enter an overide C value if desired,or leave blank to accept calculated C.)
5-yr. Runoff Coefficient, CS= 0.09
Overide 5-yr. Runoff Coefficient, C= (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
,,••.
•--------
overland LEGEND
Reach 1 flow
Reach • Q Hsng
Flew Direction
� E
Reach 3 Catha�ent
r
NRCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas&
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swales
Lawns Ground Waterways (Sheet Flow)
Conveyance 2.5 5 7 10 15 20
Calculations: Reach Slope Length 5-yr NRCS Flow Flow
ID S L Runoff Convey- Velocity Time
Coeff ance V Tf
ft/ft ft C-5 fps minutes
input input output input output output
Overland 0.0125 700 0.09 0.26 44.64
1 0.0035 425 15.00 0.89 7.98
2
3
4
5
Sum 1,125 " Computed Tc= 52.62
Regional Tc= 16.25
IV.
Peak Runoff Prediction using Computed Tc edlctlon using Regional Tc
Rainfall Intensity at Tc, I = 2.87 inch/hr Rainfall Intensity at Tc, I= 5.68 inch/hr
Peak Flowrate, Qp= 9.17 cfs Peak Flowrate, Qp= 18.17 cfs
Messner Engineering,Inc.
STA. O- '{-p
PIPE CULVERT ANALYSIS
COMPUTATION OF CULVERT PERFORMANCE CURVE
r
May 17, 2004
PROGRAM INPUT DATA
DESCRIPTION VALUE
Culvert Diameter (ft) 1.5
FHWA Chart Number 2
FHWA Scale Number (Type of Culvert Entrance) 1
Manning's Roughness Coefficient (n-value) 0.024
Entrance Loss Coefficient of Culvert Opening 0. 5
Culvert Length (ft) 50.0
Invert Elevation at Downstream end of Culvert (ft) 4,779.5
Invert Elevation at Upstream end of Culvert (ft) 4,780.0
Culvert Slope (ft/ft) 0.01
Starting Flow Rate (cfs) 0.1
Incremental Flow Rate (cfs) 0.25
�' Ending Flow Rate (cfs) 5.1
Starting Tailwater Depth (ft) 0.0
Incremental Tailwater Depth (ft) 0.0
— Ending Tailwater Depth (ft) 0.0
COMPUTATION RESULTS
Flow Tailwater Headwater (ft) Normal Critical Depth at Outlet
Rate Depth Inlet Outlet Depth Depth Outlet Velocity
(cfs) (ft) Control Control (ft) (ft) (ft) (fps)
0. 1 0.0 0.15 0.17 0.14 0.12 0. 12 1.59
0.35 0.0 0.29 0.33 0.25 0.22 0.22 2.2
QS = [ 0.6 0.0 0.38 0.43 0.33 0.29 0.29 2.54 I
0.85 0.0 0.46 0.52 0.39 0.34 0.34 2.79
1.1 0.0 0.53 0.59 0.45 0.39 0.39 2. 99
1.35 0.0 0.59 0.66 0.5 0.44 0.44 3.17
1. 6 0.0 0.65 0.72 0.54 0.48 0.46 3.33
1.85 0.0 0.7 0.78 0.59 0.51 0.51 3.47
2.1 0.0 0.75 0.84 0.63 0.55 0.55 3.6
2.35 0.0 0.8 0.89 0.67 0.58 0.58 3.73
2.6 0.0 0.85 0. 94 0.71 0.61 0.61 3.84
2.85 0.0 0.9 0. 99 0.75 0.64 0.64 3. 95
3.1 0.0 0.94 1.04 0.79 0.67 0.67 4.06
3.35 0.0 0.99 1.09 0.83 0.7 0.7 4.16
3. 6 0.0 1.03 1.14 0.87 0.72 0.72 4.26
-
3.85 0.0 1.07 1.18 0.9 0.75 0.75 4.35
4 .1 0.0 1.12 1.23 0.94 0.78 0.78 4.45
4.35 0.0 1.16 1.27 0.98 0.8 0.8 4.54
`x100 14.6 0.0 1.2 1.32 1.02 0.82 0.82 4 . 63!
4.85 0.0 1.24 1.37 1.06 0.85 0.85 4.72
5.1 0.0 1.29 1.41 1.11 0.87 0.87 4 .8
HYDROCALC Hydraulics for Windows, Version 1.2a Copyright (c) 1996
Dodson & Associates, Inc. , 5629 FM 1960 West, Suite 314, Houston, TX 77069
Phone: (281) 440-3787, Fax: (281)440-4742, Email:software@dodson-hydro.com
All Rights Reserved.
STA . s-}8s
- PIPE CULVERT ANALYSIS
COMPUTATION OF CULVERT PERFORMANCE CURVE
May 17, 2004
PROGRAM INPUT DATA
DESCRIPTION VALUE
—
Culvert Diameter (ft) 1.75
FHWA Chart Number 2
FHWA Scale Number (Type of Culvert Entrance) 1
Manning's Roughness Coefficient (n-value) 0.024
—
Entrance Loss Coefficient of Culvert Opening 0.5
Culvert Length (ft) 50.0
Invert Elevation at Downstream end of Culvert (ft) 4,779.25
Invert Elevation at Upstream end of Culvert (ft) 4,779.7
Culvert Slope (ft/ft) 0.009
Starting Flow Rate (cfs) 0.1
Incremental Flow Rate (cfs) 0.25
Ending Flow Rate (cfs) 11.35
Starting Tailwater Depth (ft) 0.0
Incremental Tailwater Depth (ft) 0.0
Ending Tailwater Depth (ft) 0.0
— COMPUTATION RESULTS
Flow Tailwater Headwater (ft) Normal Critical Depth at Outlet
Rate Depth Inlet Outlet Depth Depth Outlet Velocity
�+ (cfs) (ft) Control Control (ft) (ft) (ft) (fps)
0.1 0.0 0.14 0.17 0.14 0.11 0.11 1.56
0.35 0.0 0.27 0.31 0.25 0.21 0.21 2.15
- 0.6 0.0 0.36 0.41 0.32 0.28 0.28 2.47
0.85 0.0 0.44 0.49 0.38 0.33 0.33 2.71
1.1 0.0 0.5 0.56 0.44 0.38 0.38 2.91
1.35 0.0 0.56 0.63 0.48 0.42 0.42 3.08
- [R5 = 11.6 0.0 0.61 0.69 0.53 0.45 0.45 3.231
1.85 0.0 0.66 0.74 0.57 0.49 0.49 3.36
2.1 0.0 0.71 0.79 0.61 0.52 0.52 3.48
2.35 0.0 0.75 0.84 0.64 0.55 0.55 3.59
2.6 0.0 0.8 0.89 0.68 0.58 0.58 3.7
2.85 0.0 0.84 0.94 0.71 0. 61 0. 61 3.8
3.1 0.0 0.88 0.98 0.75 0.64 0.64 3.9
3.35 0.0 0.92 1.02 0.78 0.67 0.67 3.99
3. 6 0.0 0.96 1.07 0.82 0.69 0.69 4.08
3.85 0.0 1.0 1.11 0.85 0.72 0.72 4.16
4.1 0.0 1.03 1.15 0.88 0.74 0.74 4.24
4.35 0.0 1.07 1.19 0. 91 0.76 0.76 4.32
4.6 0.0 1.11 1.23 0.94 0.79 0.79 4.4
4.85 0.0 1.14 1.26 0.97 0.81 0.81 4.47
5.1 0.0 1.18 1.3 1.0 0.83 0.83 4.55
5.35 0.0 1.21 1.34 1.03 0.85 0.85 4 .62
5.6 0.0 1.25 1.37 1.07 0.87 0.87 4.69
5.85 0.0 1.28 1.41 1.1 0.89 0.89 4.76
6.1 0.0 1.31 1.45 1.13 0.91 0.91 4.82
6.35 0.0 1.35 1.48 1.16 0.93 0.93 4.89
6. 6 0.0 1.38 1.52 1.2 0.95 0.95 4.96
6.85 0.0 1.41 1.56 1.23 0.97 0.97 5.02
7.1 0.0 1.45 1.59 1.26 0.99 0.99 5.09
,.0'. 7.35 0.0 1.48 1.63 1.3 1.0 1.0 5.15
7. 6 0.0 1.51 1. 67 1.34 1.02 1.02 5.21
- 7.85 0.0 1.55 1.7 1.38 1.04 1.04 5.28
8.1 0.0 1.58 1.74 1.43 1.06 1.06 5.34
8.35 0.0 1.61 1.78 1.48 1.07 1.07 5.4
8.6 0.0 1.65 1.82 1.55 1.09 1.09 5.46
8.85 0.0 1.68 1.86 1.75 1.11 1.11 5.53
9.1 0.0 1.71 1. 9 1.75 1.12 1.12 5.59
...^., 9.35 0.0 1.74 1.94 1.75 1.14 1.14 5.65
9.6 0.0 1.78 1.98 1.75 1.15 1.15 5.71
9.85 0.0 1.81 2.02 1.75 1.17 1.17 5.77
10.1 0.0 1.84 2.07 1.75 1.18 1.18 5.83
10.35 0.0 1.88 2.12 1.75 1.2 1.2 5.89
10.6 0.0 1.91 2.17 1.75 1.21 1.21 5. 96
10.85 0.0 1.94 1. 92 1.75 1_,23____ 1.75 4.51A
47100: 111.1 0.0 1.97 1.99 1.75 1.24 1.24 6.081
11.35 0.0 2.04 2.05 1.75 1.26 1.26 6.14
HYDROCALC Hydraulics for Windows, Version 1.2a Copyright (c) 1996
Dodson & Associates, Inc. , 5629 FM 1960 West, Suite 314, Houston, TX 77069
Phone: (281) 440-3787, Fax: (281) 440-4742, Email:software@dodson-hydro.com
All Rights Reserved.
DurFa44.- Svl.at_.E CST AN5+235.)
— TRAPEZOIDAL CHANNEL ANALYSIS
RATING CURVE COMPUTATION
May 17, 2004
PROGRAM INPUT DATA
DESCRIPTION VALUE
Channel Bottom Slope (ft/ft) 0.005
Manning's Roughness Coefficient (n-value) 0.033
Channel Left Side Slope (horizontal/vertical) 4.0
Channel Right Side Slope (horizontal/vertical) 4.0
Channel Bottom Width (ft) 0.0
Minimum Flow Depth (ft) 0.1
Maximum Flow Depth (ft) 1.6
Incremental Head (£t) 0.1
COMPUTATION RESULTS
Flow Flow Flow Froude Velocity Energy Flow Top
Depth Rate Velocity Number Head Head Area Width
(ft) (cfs) (fps) (ft) (ft) (sq ft) (ft)
-
0.1 0.02 0.42 0.334 0.003 0.103 0.04 0.8
0.2 0.11 0. 67 0.375 0.007 0.207 0.16 1.6
0.3 0.32 0.88 0.401 0.012 0.312 0.36 2.4
0.4 0.68 1.07 0.421 0.018 0.418 0. 64 3.2
- 0.5 1.24 1.24 0.437 0.024 0.524 1.0 4.0
0.6 2.01 1.4 0.45 0.03 0.63 1.44 4.8
73 -_ ! 0.7 3.04 1.55 0.4620.037 0.737 1. 96 5. 61
5 0.8 4.34 1.69 0.472 0.045 0.845 2.56 6.4
0.9 5.94 1.83 0.482 0.052 0.952 3.24 7.2
1.0 7.86 1.97 0.49 0.06 1.06 4.0 8.0
1.1 10.14 2.09 0.498 0.068 1.168 4.84 8.8
1.2 12.79 2.22 0.505 0.077 1.277 5.76 9.6
- 1.3 15.83 2.34 0.512 0.085 1.385 6.76 10.4
_I 1.4 19.29 2.46 0.518 0.094 1.494 7.84 11.21
Wipe) 1.5 23.18 2.58 0.524 0.103 1.603 9.0 12.0
1. 6 27.53 2.69 0.53 0.112 1.712 10.24 12.8
HYDROCALC Hydraulics for Windows, Version 1.2a Copyright (c) 1996
Dodson & Associates, Inc. , 5629 FM 1960 West, Suite 314, Houston, TX 77069
Phone: (281) 440-3787, Fax: (281) 440-4742, Email:software@dodson-hydro.com
All Rights Reserved. /�
Qsa 1 . CoI + 1, ZS - 2,g�ocAS
ace
Ii , I f 6, 91 = 18.0'7 c4'S
TRAPEZOIDAL CHANNEL ANALYSIS
CRITICAL DEPTH COMPUTATION
May 17, 2004
PROGRAM INPUT DATA
DESCRIPTION VALUE
Flow Rate (cfs) 18.1
Channel Bottom Slope (ft/ft) 0.005
Manning's Roughness Coefficient (n-value) 0.033
Channel Left Side Slope (horizontal/vertical) 4 .0
Channel Right Side Slope (horizontal/vertical) 4.0
Channel Bottom Width (ft) 0.0
COMPUTATION RESULTS
DESCRIPTION VALUE
Critical Depth (ft) 1.05
Critical Slope (ft/ft) 0.0205
Flow Velocity (fps) 4.11
Froude Number 1.0
Velocity Head (ft) 0.26
Energy Head (ft) 1.31
Cross-Sectional Area of Flow (sq ft) 4.41
Top Width of Flow (ft) 8.4
HYDROCALC Hydraulics for Windows, Version 1.2a Copyright (c) 1996
Dodson & Associates, Inc. , 5629 FM 1960 West, Suite 314, Houston, TX 77069
Phone: (281( 440-3787, Fax: (281( 440-4742, Email:software@dodson-hydro.com
�A11 Rights Reserved.
,r.
APPENDIX H
CHARTS, GRAPHS,
FIGURES AND DETAILS
r
cn
- ----- - °
II _ _ — Figure 3- 1 0
TOWN OF WINDSOR , COLORADO CD
CC I
l _ RAINFALL INTENSITY- DURATION CURVES
z 5 I _L_ m
- . -
CC ►�i■wi �-
V) —
Z C= .� _ ■
I ate► a ■ ■
z 3 �� '� . .�j� _ -
O
Q er:
I CL
IIIMIIIIMISININIMPIMPla MOM b. Mk
■u/��IIA�■■urut�f ,/■■//■sirMann ■A - !�■/A�����■/�.w��_��r.
1 ■■�■��rr/��� I i"`- -����i:�lor■■/■GCC_!:!G■w
■ i �ai■/.aua ■�■�■■■�/' _ .. •�•--G11111-- -o
—.-t ....p.■■/Y/� m
CO
3 i/■i�iu ii 1 -- ---r-y aW,
1 I . 1 qn 1 nn . �,.
DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF
r
TABLE RO-3
Recommended Percentage Imperviousness Values
Land Use or Percentage
Surface Characteristics Imperviousness
Business:
Commercial areas 95
Neighborhood areas 85
Residential:
Single-family '
Multi-unit (detached) 60
Multi-unit (attached) 75
Half-acre lot or larger "
Apartments 80
Industrial:
Light areas 80
Heavy areas ._ 90
_ Parks, cemeteries 5
Playgrounds 10
Schools 50
Railroad yard areas 15
Undeveloped Areas:
Historic flow analysis 2
Greenbelts, agricultural 2
Off-site flow analysis 45
(when land use not defined)
Streets:
Paved 100
Gravel (packed) 40
- Drive and walks 90
Roofs 90
Lawns, sandy soil 0
Lawns, clayey soil 0
" See Figures RO-3 through RO-5 for percentage imperviousness.
Based in part on the data collected by the District since 1969, an empirical relationship between C and
the percentage imperviousness for various storm return periods was developed. Thus, values for C can
be determined using the following equations (Urbonas, Guo and Tucker 1990).
C, = KA + (1.3li' - 1.44i`' + 1.1351- 0.12) for C4 ≥ 0, otherwise CA = 0 (RO-6)
CCD =r Kca + 0.85813 - 0.78612 + 0.774i+ 0.04) (RO-7)
CB = (CA + CCD/l2
in which:
= % imperviousness/100 expressed as a decimal (see Table RO-3)
06/2001 RO-9
Urban Drainage and Flood Control District
Hello