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USDA Soil Conservation Service Soil Survey of Weld County, Colorado
Southern Part - Sheet Numbers 2 it 7
,r Pt. O9-O6-GG
PUD Sketch Plan
2112 Denby Ct. • Fort Collins, Colorado 8052.6 • (970) 207-0272 *fax (561) 828-8059
entail: toddkodgesdesignCearthlink.net
2004-0624
Todd Hodges Design, LLC
Soil Survey of Weld County, Colorado excerpt
Published by the United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Issued September 1980
Soil Classification #32: Kim Loam, 1 to 3 percent slopes
3!—Klan loam, 1 to 3 percent sloped. This is a deep. The potential native vegetation is dominated by bite
weU drained sna an elnanth phone and alluvial We at drama Several mid grasses, such aei western wbeatgraes
elevations of 4900 to 6,260 feet It formed in mixed ealian and needleandt read, are also present Potential Droduc-
depoatt and parent sediment front a wide variety of Iron nunea from 1,600 pound%per ane in tavonble yarn
bedrock. Included in mapping are small areal of soda&that to 1,000 pounds in unfavorable years Aa range condition
have leeway sand underlying matvni. deteriorates, the mid grasses decrease, blue grams, buf-
Typically the surface layer is brown and pale brown falograss, snakeweed yucce and fringed sage increase,
Sum about 12 ashes thick.Then 26 Inches of the utr and forage Production drone. Undetsrabfe weeds and an-
undying material is pale brown kern_ me lower Pan to a nails invade the rote asrange condition becomes poorer
depth of 80 inches is pals brown fine sandy kw. MManagement of vegetation on he soil should be bared
Permeability is moderate. Available water capacity is on taking half and lesvint half of the total atonal produe-
high The effective rooting depth a 60 inches or more. flan. Seeding m desirable if the range Mow poor condition
Surface ninon u medium,and the erosion hazard is low Srdeoaa grand. bulk blueatem, western wheatgrass, blue
In irrigated areas this soil is suited to all cropa coin- grant Pubescent whealgrass,sad created aliattlinah ate
moldy grown in the area including corn, sugar beets, mutable for seeding. The grass selected should meet the
beans,alfalfa,small grain,poatoes,and onions An exam- ,amoral requirements of livestock. It man be seeded into
pie of a suitable cropping system e a to a years of alfalfa a clean, petirm sorghum stubble, or it can be drilled into a
followed by corn.corn for silage,sugar heel*,small Arm prepared successful aeeduld. Seeding early m sPrvig has
or beans Land leveling,ditch lining f 6),and installing proven most ndea
R8• Windbreaks and enwrmnn the area
are generallyf trees well
pipebnes may he needed for proper water applications ahrnbe rnmmody grown in the area are
,.� All methods of irrigation are suitable, but furrow ir• omtom well
ma
ligation a the most common, Bveged ot tub,. doll Coat hued for roam n ea a as
Barnyard manure and aim- vegetation should be continued u many years ax
mensal fertilizer are needed for top yields possible following i Trees that are beet suited and
fn:moistened areas this soil is muted to winter wheat, have wing planting.
farfev, and sc hwn Meet. of the songs a planted to have good andenie pi Rocky anM arts,f juniper, eastern
, an
winter wheat and is summer fellows in alternate years hackberrdat,ponderosa bs b,at suited t are lcunkbrsh and
li Siberian
The asbru best are lkunkbush sumac,
to allow moisture accumulation.Generally preeapilation is lilac,Siberian pesahrub,and Amenuo plum.
too low for beneficial use of fertiliser. Wildlife i6 an important secondary use of this sod. The
dembble mad:farming: siripaoppint,and minimum til-
lage are needed to control soil blowing and water erosion cropland areas provide favorable dove. Many nos for ape nag-necked
Terracing also may be needed to eomtnd water ermine.
Pheasant and bym establishing
r ne species can
be attracted establishing areas for nesting and escape
cover. For pheasants, undisturbed nesting rover is eseen-
tiel and should be included in plans for habitat develop-
ment, especially in areas of intensive agriculture. Range-
land wildlife,for example,the pronghorn antelope,can be
attracted by developing livestock watering facilities,
managing Breatnek grazing,and reseeding where needed.
This sod has good potential for urban and recreational
development. Increased population growth in the survey
area has resulted in increased hrmeaite constriction.The
chief limiting soil feature for urban development and road
construction u the limited capacity of this sell to support
a load. Septic tank absorption fields function properly,but
community sewage systems should be provided if the
population density intreaaea.Because of the permeability
of the substratum sewage lagoons must be sealed
Lawms, shrubs, and trees grow welt Capability subclass
He irrigated, IVs nonirrifdted;Loamy Plaine range site
2412 Denby Court • Fort Collins, Colorado 80526 • (970) 207-0272 • fizz: (561)828-8059
email: toddhodgesdesign(aIearthlink.net
Todd Hodges Design, LLC
Soil Survey of Weld County, Colorado excerpt (Southern Portion)
Published by the United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Issued September 1980
Soil Classification #33: Kim Loam, 3 to 5 percent slopes
33—Kim loony 3 u 6 percent Mopes. Thin is a deep Permeability is moderate Available water capacity is
wed domed sad on plants and alluvial fan.at elevations high The effective rooting depth is 60 inches or mare
of 4,900 to 6,250 feet. It formed m mate eahan deposits Surface runoff in medium, and the erasion hazard is
end parent sediment from a wine variety of bedrock.In- moderan
chided in napping are small arose of sot that have In irrigated areas this soft Is noted to crops commonly
loamy sand°n attying materiel grown in the area Perennial grteaea and aA6ifa or close
Typically the surface layer rte brown and pale brown grown craps ehouhf be Min at lent 50 peroent of the
bare about 10 inches thick.The opper 29 inches of the un- time Contour d,tehn and corrugations can be used in w
derlyung material is pale brown loam.The lower part to a ritating close grown crops and pasture farrows,contour
depth of 60 inches is pale brown fine sandy loam- furrows, and cross slaps furrows are suitable for row
crops.Spnnkler irngatlon is also suggested Reaping tii-
lagr to a minimum and utilizing crop residue help to con-
trol erosion. Mainbming fertility ie important Crops
respond to applications of phosphorus and nitrogen.
In nonirngued areas this sod m suited to winter wheat,
barley, and sorghum Most of the acreage is planted to
miter wheat The predicted average yield is 28 bushels
per acre.The sal It summer(allowed in alternate years
to allow moisture accumulation Generate precipitation is
too low for beneficial nee of fertilizer
Stubble mulch farming,stnpetopping,and minimum til-
lage are needed to control sod blowing and water erosion
Terracing also may be needed to control wet=erosion.
The potent= native vegetation is dominated by blue
grams Several mid grasses,such as western wheetgraea
and needleandthreed, am also present Potential produc-
tion ranges from 1,600 pounds per acre in favorable years
to 1,000 pounds in unfavorable years.As range condition
detenorates, the and grasses decrease; Moe grains,buf-
fabgrass, snalnwett ypea, and fraged sage =cream
and forage production drops. Undesirable weeds and an-
nuals invade the site as range condition becomes poorer.
Management of vegetation on this col should be based
on Wdag bolt and leaving half of the total annaal psodac-
tioi Seeding is desirable if the range is in poor mention
Sideoets grapy little blueaom,western wheetgrasa,blue
Minn nineteen a tieatgnss,and crested wheaten=are
mutable for seeding The grass selected shoirE meet the
sentinel requirements of livestock. It can be seeded into
a clean, firm sorghum stubble.or it can be drilled into a
Linn prepared aeedbed Seeding early in spring has
proven most successful
Windbreaks and environmental plantings of trees and
shrubs commonly grown in the area art generally well
suited to this soil Cultivation to rohtrol competing
vegetation should be continued for as may years as
potable following planting Trees that are best suited and
have good servival are Reeky Mountain juniper. eastern
redeedar,ponderaea pine,Siberian aim,Rattan-oboe,and
hardberry The=rube beat noted are skunkbamb sumac,
lilac,&bench paaahrub,and anent=plain
Wildlife IS an important secondary use of this sail The
cropland areas provide favorable habitat for ring-neared
pheasant and mourning dove. Many mugs=species can
be attracted by establadittig areas for nesting and escape
rover. For pheasants,undisturbed nesting cover is Ma'
dal and should be included an plans for habitat develop-
ment,especially in areas of intensive agnrulture.Range-
2412 Denby Court • Fort Collins, Colorado 80526 • (970) 207-0272 • fax: (561)828-8059
email: toddhodgesdesign(dzearthlink.net
q Todd Hodges Design, LLC
Soil Survey of Weld County, Colorado excerpt (Southern Portion)
Published by the United States Department of Agriculture
Soil Conservation Service
In Cooperation with Colorado Agricultural Experiment Station
Issued September 1980
Soil Classification #46: Olney fine sandy loam, 0 to 1 percent slopes
46—Olney fine sandy loam, 0 to 1 percent slopes. are Rocky Mountain juniper, eastern redcedar, ponderosa
This is a deep,well drained soil on smooth plains at eleva- pine, Siberian elm, Russian-olive, and hackberry. The
tions of 4,600 to 5,200 feet. It formed in mixed outwash shrubs best suited are skunkbush sumac,lilac,and Siberi-
deposits. Included in mapping are small areas of soils that an peashrub.
have a dark surface layer and some small leveled areas. Wildlife is an important secondary use of this soil. The
Typically the surface layer of this Obey soil is grayish cropland areas provide favorable habitat for ring-necked
brown fine sandy loam about 10 inches thick. The subsoil pheasant and mourning dove. Many nongame species can
is yellowish brown and very pale brown sandy clay loam be attracted by establishing areas for nesting and escape
about 15 inches thick. The substratum to a depth of 60 cover. For pheasants, undisturbed nesting cover is essen-
inches is very pale brown,calcareous fine sandy loam. tial and should be included in plans for habitat develop-
Permeability and available water capacity are ment,especially in areas of intensive agriculture.
moderate. The effective rooting depth is 60 inches or Rapid expansion of Greeley and the surrounding area
more. Surface runoff is slow, and the erosion hazard is has resulted in urbanization of much of this Olney soil.
low. This soil has good potential for urban and recreational
This soil is used almost entirely for irrigated crops. It development The only limiting feature is the moderately
is suited to all crops commonly grown in the area, includ- rapid permeability in the substratum, which causes a
ing corn,sugar beets, beans, alfalfa,small grain, potatoes, hazard of ground water contamination from sewage
and onions. An example of a suitable cropping system is 3 lagoons. Lawns, shrubs, and trees grow well. Capability
to 4 years of alfalfa followed by corn, corn for silage, class I irrigated.
sugar beets, small grain, or beans. Few conservation prac-
tices are needed to maintain top yields.
r., All methods of irrigation are suitable, but furrow ir-
rigation is the most common. Barnyard manure and com-
mercial fertilizer are needed for top yields.
Windbreaks and environmental plantings are generally
suited to this soil. Soil blowing, the principal hazard in
establishing trees and shrubs, can be controlled by cul-
tivating only in the tree row and by leaving a strip of
vegetation between the rows. Supplemental irrigation
may he needed at the time of planting and during dry
periods.Trees that are best suited and have good survival
2412 Denby Court • Fort Collins, Colorado 80526 • (970) 207-0272 • fax: (561)828-8059
email: toddhodgesdesign(learthlink,net
CHURCH & Associates, Inc.
ENGINEERS& GEOLOGISTS
ENGINEERING GEOLOGY REPORT FOR
PROPOSED CATTAIL CREEK P.U.D.
PART OF SECTION 9,
TOWNSHIP 6 NORTH,RANGE 66 WEST OF THE 6m P.M.
WELD COUNTY, COLORADO
Prepared for:
CATTAIL CREEK, LLC.
C/O TODD HODGES DESIGN,LLC
1269 NORTH CLEVELAND AVENUE
LOVELAND, COLORADO 80537
JOB NO. 15255-L MARCH 18, 2003
DENVER 4501 Wadsworth Boulevard Wheat Ridge,CO 80033 CASTLE ROCK 303 660 4358
303.463.9317 Fax:303.463.9321 EVERGREEN 303.816.1455
LOVELAND 970.663.2124
TABLE OF CONTENTS
SCOPE 1
PROPOSED DEVELOPMENT 1
SITE CONDITIONS 1
INVESTIGATION 1
SITE GEOLOGY 2
MINERAL RESOURCES 3
GEOLOGIC HAZARDS 4
GEOLOGIC IMPACTS ON DEVELOPMENT 4
LIMITATIONS 5
LIST OF REFERENCES 6
FIGURE 1 -VICINITY MAP
FIGURE 2 - SITE PLAN AND LOCATION OF EXPLORATORY BORINGS
FIGURE 3-AREA GEOLOGY
FIGURE 4-MAP OF SAND, GRAVEL AND QUARRY AGGREGATE RESOURCES
FIGURE 5- SOIL SURVEY MAP
FIGURE 6-LOGS OF EXPLORATORY BORINGS
FIGURE 7 THROUGH 9-SWELL-CONSOLIDATION TEST RESULTS
FIGURES 10-GRADATION TEST RESULTS
SCOPE
As requested, we have conducted this engineering geology report for the subject site. The
purpose of our investigation was to identify site conditions regarding area suitability for the proposed
development as requested by the Weld County Planning Department.
PROPOSED DEVELOPMENT
The 161±-acre parcel is located in part of Section 9, T. 6 N., R. 66 W. of the 6th P.M. It is
proposed to divide the parcel into 8 rural-residential lots of approximately 4.00±acres and one lot of
approximately 114± acres, as presented on Figure 2. Domestic water is to be supplied by public
water. Sewer services are to be constructed on-site for each individual residence. A paved roadway is
proposed to access the 8 lots.
SITE CONDITIONS
The site is located approximately 6 miles east of Windsor, east of County Road 29 on the
north side of County Road 70. The eight 4-acre lots are located at the southeast part of the property.
This part consists of an irrigated, plowed field with slopes approximately 1% to 3% general to the
east. A southward flowing drainage way with a delineated 100-year floodplain is located along the
east boundary. Water was flowing in the drainage during this investigation. A concrete lined ditch is
located between the 114-acre lot and the 4-acre lots.
INVESTIGATION
This investigation was conducted by means of a site reconnaissance and test hole
observations conducted on March 3 and 6, 2002 by the author of this report, a Professional Geologist
as defined under House Bill 1574. Readily available maps and literature by the Colorado Geological
Engineering Geology Report
Job No. 15255-L
Page 2
Survey and US Geological Survey were also reviewed for this preliminary evaluation. Refer to the
attached List of References.
SITE GEOLOGY
The area lies in the Colorado Piedmont Section of the Great Plains Physiographic Province.
The Colorado Piedmont is an elongated trough situated adjacent to the Front Range. As mountain
uplifting occurred in Laramide times, increased stream energies at the foot of the mountains resulting
in erosion and scouring, creating the Piedmont. The site also lies in the Denver Basin, a thick
accumulation of Mesozoic sediments, which have been producers of fossil fuels.
The referenced geologic map indicates Quaternary Age eolium (Qe) underlies the west side
and Quaternary Age Piney Creek Alluvium (Qpc) underlies the east side of the property, as presented
on Figure 3. Qe is described as wind-blown clay, silt and sand. The Qpc is described as sandy to
gravelly alluvium, deposited by water. Claystone and sandstone of the upper Cretaceous Laramie
Formation (K]) was encountered in the borings underlying 7 feet to 20 feet, or more, of the surficial
soil. No outcrops of the Kl were observed on the property. The rock encountered in the test holes was
severely weathered to firm. A swell test of weathered claystone, or shale, indicates a low swell
potential. There were no faults, folds or other structural features observed in the field or delineated
on the referenced maps in this area.
Surficial soils encountered in the test holes consisted, primarily, of 6 feet to 9 feet of loose to
very loose silty sand with sandy silt underlain to 7 feet to 20 feet, or more,by gravelly sand underlain
to the maximum depths explored of 20 feet by weathered and firm claystone with sandstone. The
silty sand is moist to wet, loose to very loose and compressible having low strength characteristics.
The gravelly sand is moist to wet, dense and having moderate strength characteristics.
The Soil Conservation Service(SCS) maps indicate 2 general soil types; Kim loam and Olney
.-. Engineering Geology Report
Job No. 15255-L
Page 3
fine sandy loam. Kim loam is described as mixed alluvium and parent(bedrock) material. Olney fine
sandy loam is described as mixed outwash. The SCS maps indicate moderate erosion potential in the
Kim loam and low erosion potential in the Olney fine sandy loam. The SCS tables suggest slight
limitations in the Kim and Olney fine sandy loams for building site development and sanitary
facilities. Preliminary percolation tests provided in a report by Northern Colorado Geotech, Project
No. 034-01, dated August 30, 2001 indicates percolation rates which would support the "slight
limitation" category for sanitary facilities for the 3 sites tested.
Free groundwater was encountered in all 5 test holes at depths ranging from 5.0 feet to 9.6
feet, as indicated on Figure 6. Free water encountered in the borings is perched on relatively
impervious weathered rock. The groundwater appears to flow generally from the west to the east.
Maximum seasonal groundwater levels were not determined during this investigation, however, are
expected to rise during irrigation and wet seasons. Existing groundwater conditions are at levels in
some areas which will effect basement-level construction, onsite waster water system (OWS)
placement and roadway construction.
MINERAL RESOURCES
Colorado Geological Survey(CGS)Special Publication 5-B, referenced geologic map and test
hole data from this report were reviewed as the primary references for the preliminary evaluation of
sand, gravel and quarry aggregate resources and field verified by the geologist. The CGS publication
indicates that the east side of this parcel lies in terrace deposits (T) with a probable aggregate
resource (4) rating, as presented on Figure 4. Part of this area lies in a 100-year floodplain. Minimal
gravel was encountered in the test holes. Due to the poor quality of aggregate and relatively small
size of the deposit, it is our opinion that aggregate resources encountered on the property do not meet
quality/quantity standards for being economically commercial deposits. Three oil/gas wells and tank
+-� Engineering Geology Report
Job No. 15255-L
Page 4
batteries are located on the property.
GEOLOGIC HAZARDS
Environmental Geology 6 of the Colorado Geological Survey indicates very gentle to
moderate slopes exist on the property. Our observations indicated no signs of active or past
movement due to unstable slopes. Based on this information, it is our opinion that there are no
geologic hazards caused by gravity on the property. Man-made activities, such as deep excavations,
may create conditions, which could result in gravity-caused geologic hazards.
GEOLOGIC IMPACTS ON DEVELOPMENT
The interaction of the proposed development and the geology of the site will depend on the
types of structures proposed and specific geologic influences. The primary structures to be built are
building foundations, paved roadway and onsite wastewater systems(OWS).
FOTTNDATTONS• The upper silty sand and sandy silt exhibits low to very low bearing
characteristics. Shallow groundwater, which may interfere with basement-level construction, also
exists in some of the proposed building areas. Foundation depths should be limited to provide a safe
buffer between potential high groundwater and floors. Dewatering methods may also be useful in
lowering groundwater, allowing lower foundation levels. Foundation subgrades may require a
stabilizing layer of gravel or other methods to improve bearing support. Site-specific geotechnical
investigations are recommended for each structure to determine soil strengths, swell potentials,
groundwater levels and make recommendations for design and construction.
ROADWAYS- It is our understanding that the proposed interior roadway is to be paved. A
geotechnical investigation is recommended for the roadway so that the pavement structure can be
designed for the appropriate soil, groundwater and traffic conditions. The high groundwater and very
., Engineering Geology Report
Job No. 15255-L
Page 5
loose to loose soil conditions often result in pavement subgrades that may not be able to be stabilized
with conventional compaction methods. Subgrades for paved roadways must be relatively non-
yielding in order to compact the base course and asphalt layers. Various methods, which may consist
of soil replacement, chemical stabilization, or geogrid/geotextile placement, may be required to
provide a stable subgrade for paving.
ONSTTF WASTEWATER SYSTEMS COWS). Preliminary percolation tests provided in a report by
Northern Colorado Geotech indicates percolation rates'of 12, 20 and 45 minutes per inch (MPI) at
the 3 locations tested. Groundwater levels and high as 5 feet were encountered for this investigation
and are expected to rise during irrigation and wetter seasons. Four feet of separation is required from
maximum seasonal groundwater to the bottoms of the drain fields. Mounding of drain fields is a
common method to accommodate shallow groundwater conditions. Site-specific percolation
investigations for OWS are required by the County Health Department prior to issuance of a building
permit. Engineered systems will be required where groundwater separation requirements cannot be
met with existing conditions.
GEOLOGIC HA7ARDS• The site observations and referenced map did not indicate signs of
geologic hazards caused by gravity, such as landslides, debris flows, rock fall, or unstable or
potentially unstable slopes. Man-made activities could produce conditions, which may result in
hazardous conditions, if not carefully planned No geologic hazard mitigation is anticipated for this
site. Excavations for foundations, utilities and other structures may need to be protected from caving.
Refer to OSHA standards for the appropriate protection methods.
LIMITATIONS
This study was preliminary in nature and did not include an extensive exploration program for
the presence of oil, natural gas, uranium or other mineral resources. Based on existing maps,
Engineering Geology Report
Job No. 15255-L
Page 6
._ literature and field data potential sand,gravel and quarry aggregate resources are not believed to exist
in economic quantities or quality. Although no geologic or soil hazards appear to exist in the present
condition, site-specific geotechnical and onsite wastewater investigations should be conducted for
each lot.
If we can be of further service in discussing the contents of this report, or to conduct site-
specific investigations, please call.
�o..a.%.nuo
CHURCH&Associates,Inc. trot%°,%%%%%FSS1oN4or
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•
Thomas W. Finley,C.P.G. % T':•.,r f1445,0 As vi.t\v vsb4twf
3 copies sent
LIST OF REFERENCES
Colton, Roger B., 1978,Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado: U.S.
Geological Survey Map I-855-G
Johnson, Erin J.,and Himmelreich,John W. Jr., 1998, Geologic Hazards Avoidance or Mitigation:
Colorado Geological Survey Information Series 47
Leafgren, Doug, 2001, Preliminary Geotechnical Engineering Report — Proposed Shepardson PUD-
Weld County Roads 20 and 29, Weld County, Colorado, Northern Colorado Geotech Project No.
034-01
Rogers, W.P.,Ladwig,L.R.,Hombaker,A.L., Schowchow, S.D., Hart, S.S., Shelton,D.C., Scroggs,
D.L., and Soule, J.M., 1979, Guidelines and Criteria for Identification of Land-Use Controls of
Geologic Hazard and Mineral Resource Areas, Colorado Geological Survey Special Publication 6
Schowchow, S.D, Shroba,R.R., and Wicklein,P.C., 1974,Atlas of Sand, Gravel, and
Quarry Aggregate Resources Colorado Front Range Counties: Colorado Geological Survey Special
Publication 5-B
Shelton, D.C., Rogers, W.P., 1987, Environmental and Engineering Geology of the Windsor Study
Area,Larimer and Weld Counties, Colorado,Colorado Geological Survey Environmental Geology 6
Tweto, Ogden, 1979, Geologic Map of Colorado: U.S. Geological Survey
, 1980, Soil Survey of Weld County (Northern part, Southern part), Colorado: U.S.
Department of Agriculture Soil Conservation Service
PROPOSED CATTAIL CREEK P.U.D. SCALE
PART OF SECTION 9, 1 : 50,000
T. 6 N., R. 66 W. OF THE 6TH P.M.
WELD COUNTY, COLORADO N
I
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6 :y49/499
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•
��!SITE
COUNTY ROAD 70 ��• ��
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R.66W.
VICINITY MAP
JOB NO. 15255-L FIGURE 1
PROPOSED CATTAIL CREEK P.U.D. SCALE
1" = 600'
PART OF SECTION 9
T. 6 N., R. 66 W. OF THE 6TH P.M.
WELD COUNTY, COLORADO
-411
LOT g 100-YEAR
1.4.56 ± ACRES FLOODPLAIN
•
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APPROXIMATE LOCATION OF TH-5 ;
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_._..._.WELISCOWNTY NoAD 70
TH-1 •
DRAWING BASED ON PRELIMINARY PLAT BY INTERMILL LAND SURVEYING
PROJECT No. P-02-5081, DATED 1-17-03
SITE PLAN AND LOCATION OF
JOB NO. 15255-L EXPLORATORY BORINGS FIGURE 2
PROPOSED CATTAIL CREEK P.U.D. SCALE
PART OF SECTION 9, 1 : 50,000
T. 6 N., R. 66 W. OF THE 6TH P.M. k
WELD COUNTY, COLORADO
N
I
, . 1 utter - v'uLGJ,
f 4,Ry l` ake
`) ' 1
Woods OP P' \
• 1 Lake i
Ni 1a
..l x` RM 2Are9
BM 8 t_, J
(1 ., 7 2
t' s SITE
tiee 4816
1 V % (/468)
Neff
Lake
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— • ' % 4' I.
KEY
QE — QUATERNARY EOLIUM, WIND—BLOWN CLAY, SILT AND GRANULES
QPC— QUATERNARY PINEY CREEK ALLUVIUM, SANDY TO GRAVELLY ALLUVIUM
69 — DEFLATION BASIN
BASED ON USGS MAP I-855-G
AREA GEOLOGY
JOB NO. 15255-L FIGURE 3
PROPOSED CATTAIL CREEK P.U.D. SCALE
PART OF SECTION 9, 1 :37,500
T. 6 N., R. 66 W. OF THE 6TH P.M.
WELD COUNTY, COLORADO N
I
fit-
Woods Lake ' , •
i
1,.
m ti
1.
ti
SITE 10
nJ
� l e jCICr,�ii�i
- P1\ /
.
KEY
V-VALLEY FILL DEPOSITS
4-PROeABLE AGGREGATE RESOIRCE
BASED ON: ATLAS OF SAND, GRAVEL 8 QUARRY RESOURCES - COLORADO FRONT RANGE COIMTIES
COLORADO GEOLOGICAL SURVEY SPECIAL PUBLICATION 5-B (1974)
MAP OF SAND, GRAVEL & QUARRY AGGREGEATE RESOURCES
JOB NO. 15255-L FIGURE 4
r-
1' = 200
.e
PROPOSED CATTAIL CREEK P.U.D. SCALE
PART OF SECTION 9, 0'
T. 6 N., R. 66 W. OF THE 6TH P.M.
WELD COUNTY, COLORADO N
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SOIL SURVEY IS BASED ON USDA SOIL SURVEY OF WELD COUNTY,COLORADO
SOIL SURVEY MAP
JOB NO. 15255-L FIGURE 5
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EXPLANATIONS: I'1 8/12 INDICATES THAT 8 BLOWS OF A 140 POUND HAMMER FALLING 30 INCHES WERE
REIREDDANE
® TOPSOIL . SAND,SLIGHTLY GRAVELLY TO GRAVELLY, a TOA26 INCH O.D.SAMPLER 12 INCHES
WET,DENSE,Leff BROWN
1 INDICATES DEPTH TO FREE WATER AND THE NUMBER OF DAYS AFTER DR UJNO THE
77 MEASUREMENT WAS TAKEN
7 SAND,SILTY,SLIGHTLY CLAYEY,MOIST TO ® WEATHERED CLAYSTONE WRH
.,r HT TO LOOSE, BROWN TO SANDSTONE,
GREY TO OLIVE UM TO FIRM,
tLNOTES: 1. THE EXPLORATORY BORINGS WERE DRILLED ON 33-03 USING A4-INCH
DIAMETER CONTINUOUS RIGHT AUGER POKER®BY CME46B DRILLING RIG.
I CLAYSTONE WITH SANDSTONE,MOIST, 2. FREE WATER WAS ENCOUNTERED AT THE TIME OF DRILLING AS SHOWN.
FIRM TO HARD,OW GREY TO OLIVE 3. WC- WATER CONTENT(%) DO-DRY DENSITY(PCP)
-200-PERCENT OF FINES PASSING THE NUMBER 200 SIEVE
LL-LIQUID UNIT PI-PLABITICRY INDEX
NP.NOT POSSIBLE
LOGS OF EXPLORATORY BORINGS
JOB NO.15255-L FIGURE 6
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APPLIED PRESSURE -ksf
Sample of Silty Sand From TH-1 @ 3'
�... Natural Dry Unit Weight = 99 PCF
Natural Moisture Content = 27.1 %
JOB NO. 15255-L SWELL-CONSOLIDATION TEST RESULTS FIGURE 7
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APPLIED PRESSURE -ksf
Sample of Claystone from TH-3 @ 19'
.� Natural Dry Unit Weight = 108 PCF
Natural Moisture Content = 23.7 %
JOB NO. 15255-L SWELL- CONSOLIDATION TEST RESULTS FIGURE 8
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APPLIED PRESSURE-ksf
Sample of Clayey Sand from TH-4 @ 9'
Natural Dry Unit Weight = •126 PCF
Natural Moisture Content = 12.4 %
JOB NO. 15255-L SWELL - CONSOLIDATION TEST RESULTS FIGURE 9
CHURCH & Associates, Inc.
Engineers & Geologists
Denver,Colorado 303-463-9317
Evergreen,Colorado 303-816-1455
Castle Rock,Colorado 303-660-4358
Loveland,Colorado 970-663-2124
Gradation Test Results
#200 #100 #50 #30 #16 #8 #4 3/8" 3/4' 1-1/2' 3"
100.0 0
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20.0 .NI .ICI 80
10.0 I� 90
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0.0 100
0.01 0.1 I 10 100
Diameter al Particle in Millimeters
DESCRIPTION: SILT, VERY SANDY,CLAYEY,VERY MOIST,
VERY LOOSE,BROWN
GRAVEL 3% HOLE/SAMPLE TH-4
SAND 41% DEPTH 4'
FINES 56% LIQUID LIMIT 27
MOISTURE 23.8% PLASTICITY INDEX NP
DRY DENSITY(ref) N/A
DATE: 3-17--03
JOB NAME: Cattail Creek, LLC
JOB NUMBER 15255-L FIGURE 10
-
PRELIMINARY 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 Creek, LLC
P. O. Box 68
Windsor, Colorado 80550
December 2003
Project No. GRD - 431 - 02
Prepared by:
—
MESSNER Engineering Inc.
150 East 29th Street, Suite 270 Loveland, Colorado 80538-2765 Telephone: (970) 663-2221
- 1S f lZ 2lS V E,
Engineering, Inc.
Project No. GRD - 431 - 02
December 11, 2003
John Shepardson
Cattail Creek, LLC
P. 0. Box 68
Windsor, Colorado 80550
Dear Mr. Shepardson,
The enclosed report represents the results of the Preliminary 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.
— r-•
Respectfully Submitted,
_ MESSNER Engineering, Inc.
Cameron W. Knapp, Civil Engineer
"I hereby state that this preliminary 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 establis y WeldCounty."
MEysF•G
•
•
•
Dennis R. M *,r ••C.
Zr
Registered Pregifnpal Engirt/
State of Colora&% f41i 15O7,;:
/2-/i-d7
— i
Civil Engineering Consultants
150 E. 29th Street, Suite 270 Loveland, Colorado 80538 (970) 663-2221
TABLE OF CONTENTS
Description Page
LETTER 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
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. Another
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.fs. during the 5-year storm and
30.03 c.f.s. 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 c.£s.
during the 5-year storm and 12.28 c.fs. 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.f.s. 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.£s. and 4.54 c.£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.£s. and the 100-year peak runoff rate will increase by 4.06 c.£s.
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
1. 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.
— r--
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
v
1 ,
1 \ To determine if flood insurance is available in this community
• contact your Insurance agent,or call the National Flood Insurance
eProgram at(800)638-6620.
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0 2000 FEET
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\ oso� FLOOD INSURANCE RATE MM
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6 4 3 1 2 (SEE MAP INDEX FOR PANELS NOT PRINTEC
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8
y� COMMUNITY-PANEL NUMBER
080266 0475 C
•
7 8 9 0 2 MAP REVISED:
SEPTEMBER 28, 1982
Gfr federal emergency management agenci
17- 16- ii:i 15 14 13
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In
Flowline of Exi Ling ` p.
Concrete Di chi
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�` Area of 100 Year Flood Per FEMA Map V ) ca' ' »:
Community Panel No. 080266-0475—C, 0 w`
Existing 18" �� Dated September 28, 1982 III
a c -
CMP Culvertss� e o ti
'c r/-7" / ,,,, I _ �'A. 50 200 w m V N
—� � \ Existing 18" sm. Li
D �� �D c
CMP Culvert 1' = zoo' 1_w
cs ': .--) ?
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�'c Existing 18"
a' CMP Culvert — —5012— _ Typically Indicates Existing z w
Ground Surface Contour ri i-
U F-
-- Drainage Basin Limit Identifier --
�� k\:464.91 ac. oATE: Drc tt 7nn3
Existing Box o,_ Typically Indicates Drainage—b �p —� . 3q \ Culvert Bridge Flow Direction crslr; AS NOTED
tklil:\ , ,\ ` Concentration Point Identifier DRAWN: MLD.
— —� —.F �.__�.�. - - u um— CHKD: D.R.M
WELD COUNTY -ROAD 70 ' ,_-__;_---___> - _ _ �\ — #4 Basin tr.--DeBasin Number Design Point, N b
Project No.
— — Area of basin in Acres
GRD-431-02
Existing 24" J Existing 36" 5.23 ac. Q100c.f.s.
CMP Culvert Existing 24" CMP Culvert 3.4 6.7 SHEET
CMP Culvert Q5 c.f.s. 1 of 2
2.
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Concrete tch _ .
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i _ \ Irrigation Ditch
a 2
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ci
Existing 12" ' \ \ \ ...)... i I I I /Jl/ ) \ 1 i / E
CMP Culvert 11 y I 7t1 .\ \ / I / / �- o rq
\ I I/ / / ��\\ Area of 100 Year Flood Per FEMA Map Ct c .; 12
....t.\ \ ....t. y / c: Community Panel No. 080266-0475—C, w N
Existing 18" ) °��, .� \ \ /�/ �� Dated September 28, 1982 Cip �,
CMP Culvert —T' -
7% \7 / -/ �\, Existing 18" 0 100 300 c
—
to
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\ �y
i
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1,1J� d �� � 13:17 ac.
T� \\
/ A /,7 1 .40 .2.3
0
xisting 12 \\\ \ Loed)\
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�1 \ � AV�� 1 .256.97 � ,�; W owci
�� '"� V\ n� Flowline of Proposed w
C• _J \\` �;--- -- "�--/ Drainage Swale a w
_� \ 8. ac. \ \\` Pro osed x o co>
\ \CM Culve t Existing 18" a gR
1 .61 11 .1 1 .1 \ \ CMP Culvert r- 1 4:12449
Flowline of Existing \
Concrete Ditch 1. �'t\` \ V `�
\ \� — —5012— _ Typically Indicates Existing H
\ \� Ground Surface Contour Qi
\ �\ ',�� J \�� Existing 18"
V �� �\ CMP Culvert —3012— Typically Indicates Proposed z
L \�` \\ b / ,� Finish Surface Contour U
F1 A /'D �� �1 �� �— Drainage Basin Limit Identifier
36.9 ac:.
36.92 a \ �\ Existing Box o-_ Typically Indicates Drainage DATE: DFC. 11. 2003
I 1 !
I I proposed —b 1 '159'17 Culvert Bridge Flow Direction SCALE: AS NOTED
,- I , — —. .664.5 ` — Ci Ivert — —_ — _ _ �♦ Concentration Point Identifier DRAWN: M.LD.
1 # Design Point, Basin Number CHKD: D.R.M
WCLD COUNTY -Rea 79 — — �: _ — 4 Basin 'e' e
Existing 24" —
0 P' e°ale �a' 478 47• 478 :r 4779 4778----4777----- ' — Area of basin in Acres Project No.
GRD-431-02
o-^ R^ a^ "� a Flowline of Existing Existing 36" 5.23 cc. SHEET
CMP Culvert Existing 24" CMP Culvert 3.4 6.7 05c.fQmoc.f.s.
CMP Culvert Roadside Ditch(typ) qs c.f.s. 2 of 2
APPENDIX I
DRAINAGE S UMMAR Y
- DRAINAGE CALCULATIONS
DRAINAGE SUMMARY
EXISTING CONDITIONS:
Sub-Basin Area Imper. Qs Q100
(acres) (%) (c.fs.) (c.f.s.)
'A' 36.92 2.39 3.41 30.03
Sum: 36.92 Sum: 3.41 30.03
_ PROPOSED CONDITIONS:
Sub-Basin Area Imper. Qs Q,so
(acres) (%) (c.fs.) (c.f.s.)
'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
Sesi
LEGEND:
Flow Direction
le 4
Subarea 3 C#chal
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. 36.54 2.00 73.08
Gravel 0.38 40.00 15.20
sum: 36.92 Sum: 88.28
Area-Weighted Runoff Coefficient(sum CA/sum 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 Tide: CATTAIL CREEK P.U.D.
Catchment ID: EXISTING SUB-BASIN'A' (5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID=
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)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= 0.08
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 gay.
Reach2• O Beginning
• Flow Direction
Beach 3 Catchment
.� Bowden-
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 edictlon 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 Syr. Runoff Coefficient, C = (enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)
Illustration
overland LEGEND
Reach I flew
Reach 2. Q Ilmbocing
. Flow Dtrecttaa
Reach 3 Catrh.rent
Bela+darr
N RCS Land Heavy Tillage/ Short Nearly Grassed Paved Areas&
Type Meadow Field Pasture/ Bare Swales/ Shallow Paved Swale*
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
eel
S
LEGEND:
Flow Direction
eo 14
S&MgCatchment
Sabana 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. 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)=Cl "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 LEGEND
Reach 1 flow
Reach 2• O Brig
Flow Direction
� 4
Reach 3 catchment
Barmy
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 49.35
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, Qp= 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=
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= 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 •
RowLEGEND
Reach I
Beach 2 i O &ginning
• Fin Direction
.� Reach 3 Catchment
Bonnaaa.
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 49.35
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 = 2.55 inch/hr Rainfall Intensity at Tc, I= 5.26 inch/hr
Peak Flowrate, Op= 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
es�
soiol
_ LEGEND:
Flow Direction
es
S
Subarea Caebm eat
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 CAlsum 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)=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= 0.15
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
�. •-
-------
�
overland LEGEND
Reach I flow
Reach . O Bias
Flaw 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 j 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, Qp= 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)AC3
— 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= 0.41
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
overland •
LEGEND
Reach l flow
Reach 2. O Best,nring
Flew Directive
E
Reach 3 Catchment
Bo.ndq
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 0.0450 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.
r Peak Runoff Prediction using Computed Tc edlction using Regional Tc
Rainfall Intensity at Tc, I= 4.92 inch/hr Rainfall Intensity at Tc, I= 5.66 inch/hr
— Peak Flowrate, Qp= 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
s
LEGEND:
now Direction
ell 1: 4
S
Subarea Cxchme>o2
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. 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 CAlsum 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
overland LEGEND
Reach 1 gay.
Reach 2• O Begbiaing
• ,Flew Direction
Catchment
Reach B
3 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 j 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= 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 Title: CATTAIL CREEK P.U.D.
Catchment ID: PROPOSED SUB-BASIN'C' (100-yr Storm)
I. Catchment Hydrologic Data
._ Catchment ID=
Area= 8.10 Acres
Percent Imperviousness= 6.47 96
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)
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= 0.39
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
Ovende 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 Raw
Reach 2• O Beginning
• ,flow Direction
Reach 3 Catchment
Beamlary
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
fUft 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 To= 15.33
IV.
Peak Runoff Prediction using Computed Tc edlction using Regional Tc
Rainfall Intensity at Tc, I= 3.55 inch/hr Rainfall Intensity at Tc, 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
Illustration
Sa-eel
LEGEND:
Flaw Direction
S Calvinist=
Subaaa 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 SUS-BASIN'D'(5-yr Storm)
I. Catchment Hydrologic Data
Catchment ID= 'D'
Area= 3.66 Acres
Percent Imperviousness= 6.52 %
NRCS Soil Type= 8 A, 8, 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 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= 0.11
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 Bow
Reach 2• O Deeming
Flow Direction
Reach 3 Cahliaent
Bandon
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 T1
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)=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")
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 gay
Reach 2• O Degbwdng
• Flow Directba
Reach 3 Catchment
�.. Boaniarr
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.
Peak Runoff Prediction using Computed Tc ediction using Regional Tc
Rainfall Intensity at Tc, I= 3.20 inch/hr Rainfall Intensity at Tc, I= 6.15 inch/hr
Peak Flowrate, Qp= 4.54 cfs Peak Flowrate, Qp= 8.70 cfs
Meaner Engineering,Inc.
Area-Weighting for Runoff Coefficient Calculation
Project Title: CATTAIL CREEK, P.U.D.
Catchment ID: PROPOSED SUB-BASIN
Illustration
sal"`e$1
LEGEND:
Flow Direction
n1>a`'
s 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)"CS
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")
M. 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
avert LEGEND
Reach 1 flay
Reach 2• O Beenniag
• .Flay Diasifoa
Reach 3 Catchment
Bnndarr
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 ediction using Regional Tc
Rainfall Intensity at Tc, I = 1.43 inch/hr Rainfall Intensity at Tc, I= 2.84 inch/hr
Peak Flowrate, Op= 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'El(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)
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= 0.09
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 flaw
Reach 2. O Bed
• Flow Directing
Reach 3 Catchment
Boundary
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 ediction using Regional Tc
Rainfall Intensity at To, I= 2.87 inchmr Rainfall Intensity at Tc, I = 5.68 inch/hr
Peak Flowrate, Qp= 9.17 cfs Peak Flowrate, Qp= 18.17 cfs
Messner Engineering, Inc.
APPENDIX H
CHARTS, GRAPHS,
FIGURES AND DETAILS
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DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF
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.a = Ka + (1.31i 3 - 1.4412 + 1.135i— 0.12) for C4 ≥0, otherwise CA =0 (RO-6)
Cc0 = KOD + @.858i' — 0.786i2 + 0.774i+ 0.04) (RO-7)
Cs — �C + CCD)I2
in which:
= °/0 imperviousness/100 expressed as a decimal (see Table RO-3)
06/2001 RO-9
Urban Drainage and Flood Control District
Preliminary Drainage
Investigation and Erosion
Control Report contains
oversized map
Please see original file
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